Additive

Abstract

The present invention relates to an additive comprising biochar particles for cement and concrete. The present invention also relates to cement and concrete comprising the additive and a method for producing cement or concrete.

Description

[0001] ADDITIVE

[0002] FIELD OF THE INVENTION

[0003] The invention relates to additives for cement and concrete . The invention also relates to cement and concrete comprising the additive which may be electrically conductive and a method for producing cement or concrete comprising the additive .

[0004] BACKGROUND OF THE INVENTION

[0005] Carbon holds potential to impact the performance and applicability of cement and concrete due to their inherent high strength and electrical conductivity . Many carbon materials are superior conductors of electricity and can lead to electrically conductive cement and concrete formulations . Conductive cement and concrete are relatively new concepts with the potential to solve long standing problems such as corrosion protection of steel reinforcements within the cement and concrete as well as enable modern-day applications and ' smart ' cement and concrete .

[0006] Newly identi fied applications such as anti-static flooring and electromagnetic shielding continue to grow and demand new types of cement and concrete that can meet the continually advancing speci fication requirements . Smart cement and concrete , on the other hand, is j ust beginning to take root and will evolve further as new enabling materials enter the market . Some of the possibilities of ' smart ' cement and concrete that are driving the development include : strain sensing, temperature sensing, damage detection, thermoelectric behavior for electrical generation or conversion; electrical conduction, anti-static and EMI management , and resistive conduction properties for direct heating of cement and concrete for melting ice and snow and / or enabling installation at lower temperatures ; to name a few .

[0007] The above may be achieved through the use of specialty carbon materials such as functionali zed carbon nanotubes ( CNTs ) and carbon nanofibers ( CNFs ) . These hold great potential , but processing and cost considerations make the solutions unlikely in the near term . For example , in addition to the high cost of carbon nanomaterials , they are typically treated in a solution of sul furic acid and nitric acid to oxidi ze prior to addition to a cement paste . Mass fractions of carbon may be less than 1 % , but excessive costs and carbon footprint of the materials and processing will limit their use .

[0008] As such, practical carbons must be developed in order to see new formulations in the cement and concrete market .

[0009] SUMMARY

[0010] According to a first aspect , an additive for cement or concrete comprising biochar particles is provided .

[0011] According to a second aspect , cement or concrete comprising the additive according to the first aspect is provided . In embodiments of this aspect of the invention, the cement or concrete may be electrically conductive .

[0012] According to a third aspect , a method for producing cement or concrete is provided, the method comprising : a . providing a mixture comprising one or more cement powders and the additive according to the first aspect ; b . adding water to the homogenous mixture to obtain an aqueous mixture ; c . adding the aqueous mixture to a form; and d . curing the aqueous mixture .

[0013] BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings , which are included to provide a further understanding of the invention and constitute a part of this speci fication, illustrate embodiments of the invention and together with the description help to explain the principles of the invention . In the drawings :

[0014] Figure 1 shows cement comprising carbon fiber, and

[0015] Figure 2 shows cement comprising biochar particles and carbon fiber .

[0016] Figure 3 is a bar chart showing conductivity measurements from cement samples comprising di f fering levels of biochar and carbon fiber .

[0017] Figure 4 is a bar chart showing compression strength values observed from concrete compositions comprising di f fering amounts of biochar .

[0018] Figure 5 is a scatter plot showing compression strength values observed from concrete compositions comprising di f fering amounts of biochar .

[0019] Figures 6A and 6B are schematic diagrams of a set of steps formed of concrete compositions of the invention .

[0020] Figure 7 is an infra-red image of a concrete step formed of a concrete composition of the invention s demonstrating its conductivity .

[0021] DETAILED DESCRIPTION

[0022] It is obvious to a person skilled in the art that with the advancement of technology, the basic idea of the invention may be implemented in various ways . The invention and its embodiments are thus not limited to the examples described below, instead they may vary within the scope of the claims .

[0023] Unless otherwise indicated, all numbers expressing quantities of ingredients , properties such as wt . -% . , particle si ze , and so forth as used in the speci fication and claims are to be understood as being modi fied in all instances by the term "about . " Accordingly, unless otherwise indicated, the numerical properties set forth in the following speci fication and claims are approximations that may vary depending on the desired properties sought to be obtained in embodiments of the present invention . Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations , the numerical values set forth in the speci fic examples are reported as precisely as possible . Any numerical values , however, inherently contain certain errors necessarily resulting from error found in their respective measurements .

[0024] Unless otherwise stated, all percentages provided herein are weight percentages .

[0025] Additive for cement / concrete

[0026] According to a f irst aspect , an additive for cement comprising biochar particles is provided .

[0027] For the avoidance of doubt , as is apparent from the accompanying disclosure herein, the additive of thi s aspect of the present invention imparts advantageous properties both to cement compositions and also to compositions comprising cement , e . g . concrete . Thus , the term ' cement additive ' encompasses additives which are to be added directly to cement compositions , or which also may be mixed with other components of compositions comprising cement . Thus , in addition to being a cement additive , in embodiments in which the additive is comprised in a concrete composition, the additive of the invention may be a concrete additive .

[0028] Accordingly, according to this aspect of the invention, there is also provided an additive for concrete comprising biochar particles .

[0029] The biochar particles of the additive according to this first aspect may comprise at least 85 wt . -% carbon . The biochar particles may comprise at least 87 wt . - % carbon, such as at least 90 wt . -% carbon, or at least 93 wt . -% carbon . The biochar particles may comprise 87 to 100 wt . -% carbon, or 90 to 100 wt . -% carbon, or 93 to 100 wt . -% carbon .

[0030] The carbon content of the biochar particles may be measured according to DIN 51732 : 2014- 07 .

[0031] The aforementioned carbon amount gives the advantage of improved conductive properties compared to additives comprising biochar particles having a lower carbon amount . Without wishing to be bound by theory, the inventors have found that biochar having a high carbon content form organi zed atomic structures , such as graphene and graphite layers and other structures that increase the conductivity of the biochar particles . Thus , in embodiments of the invention, the additive may be electrically conductive .

[0032] Additionally, a further advantage of the present invention is the utili zation and long term storage of carbon captured from the atmosphere to reduce carbon dioxide levels . While the inclusion of biochar in cement and concrete compositions would have been expected to reduce the strength of the resulting cement and concrete compositions , the inventors have surprisingly and unexpectedly found that this did not happen signi ficantly and, to the contrary ( and as demonstrated in the accompanying examples ) , the inclusion of biochar in cement and concrete compositions either had no adverse impact on strength, or actually enhanced the strength of the concrete , whether that biochar was conductive or not .

[0033] Biochar comprised in the additive of the invention may be present in particulate form . Advantageously, owing to the versatility of the additive , biochar particles of di f fering si zes may be employed to be incorporated into cement and concrete compositions to replace a range of constituent components of those compositions . In some embodiments, the additive (or the resulting cement or concrete composition comprising the additive) may comprise one or more of the following four grades of biochar particles: (1) bulk biochar, (2) biochar coarse aggregate, (3) biochar fine aggregate, and (4) biochar powder.

[0034] Bulk biochar is comprised of fragments of biochar and may comprise a wide size distribution, for example with at least 60% of the material by mass having a size greater than 50mm. In certain embodiments, the mean average particle size of bulk biochar is about 25mm to about 500mm, about 30mm to about 300mm or about 40mm to about 100mm.

[0035] In one embodiment, the bulk biochar comprises biochar produced from wood chip feedstock. In one embodiment, the wood chip may be first processed as a biomass with a wood chipper to create randomly sized pieces ranging in size from a few millimeters to tens of centimeters in the largest dimension. These wood chips may be processed to limit the minimum and / or maximum size and then processed through a biochar production system to create a biochar with a shape nearly identical to the feedstock and with a size about 20 to 80% of the feedstock. The bulk biochar may be used as-produced in a biochar production system, or it may be processed further to reduce the size of the fragments, control the shape, and / or limit the size of the fragments used, to provide a maximum size and / or minimum size.

[0036] Biochar coarse aggregate is comprised of fragments of biochar with irregular shape and a mean average particle size of about 2mm to about 100mm, about 3mm to about 75mm or about 5mm to about 50mm. In some embodiments, the sides of the three- dimensional fragment of biochar coarse aggregate may be unequal, with an overall irregular shape. In some embodiments, two or more sides of the three-dimensional fragment of biochar coarse aggregate may be equal, with a symmetrical shape. Symmetrical shapes are typically found when processed biomass feedstocks are used in the production of the biochar. The biochar fragments may be used as-produced in a biochar production system, or they may be processed after to reduce the size of the fragments, control the shape, and / or limit the size of the fragments used, to provide a maximum size and / or minimum size.

[0037] Biochar fine aggregate may be comprised of fragments of biochar with regular and / or irregular shape. In embodiments, the mean particle size of biochar fine aggregate is about 100pm to about 10mm, about 250pm to about 7.5mm or about 500pm to about 5mm. In some embodiments, the sides of the three- dimensional fragment of biochar fine aggregate may be unequal, with an overall irregular shape. In some embodiments, two or more sides of the three-dimensional fragment of biochar coarse aggregate may be equal, with a symmetrical shape. In one embodiment, the shape and degree of symmetry of the biochar fine aggregate is controlled through classification equipment, such as sieving equipment and / or air classifiers. In some embodiments, the biochar fragments may be processed to reduce the size of the fragments, control the shape, and / or limit the size of the fragments used, to provide a maximum size and / or minimum size.

[0038] Biochar powder is comprised of biochar particulate with a mean particle size of about 1pm to about 500pm, about 2pm to about 300pm or about 5pm to about 100pm. In some embodiments, the sides of the three-dimensional fragment of biochar fine aggregate may be unequal, with an overall irregular shape. In some embodiments, two or more sides of the three-dimensional fragment of biochar powder may be equal, with a symmetrical shape. In one embodiment, the shape and degree of symmetry of the biochar fine aggregate is controlled through classification equipment, such as sieving equipment and / or air classifiers. In some embodiments, the biochar fragments may be processed to reduce the size of the fragments, control the shape, and / or limit the size of the powder used, to provide a maximum size and / or minimum size.

[0039] Many types of biochars may be used for the various grades of biochar discussed above. Biochars may be differentiated by source of biomass, such as compressed wood waste, including pine pellets, agriculture residuals, such as walnut shells, peach pits, olive pits, and others, tree waste, forest undergrowth, and a variety of other sources.

[0040] In one embodiment, more than 60%, or more than 70%, or more than 80% of the biochar particles of the additive according to the first aspect may have a particle size of less than 110 pm. The above percentage may refer to the percentage of the number of particles.

[0041] The biochar particles may have a round, squared, rectangular or star shape or any combination thereof. The biochar particles may also be bent such that they have a banana, U-, or L-shape. The skilled person will understand that the shape of the biochar particles depends on the feedstock for preparing the particles as well as the production process, including downstream modifications.

[0042] The above particle size may refer to the length of the largest dimension of the biochar particle. The largest dimension of the biochar particle may refer to the diameter of the smallest sphere in which the biochar particle would fit. For the avoidance of doubt, the sphere refers to a fictitious sphere.

[0043] The particle size may be measured according to ISO 13322-2:2021 for example by using the CAMSIZER X2 manufactured by Microtrac.

[0044] It has been found that providing biochar particles with a particle size of less than 110 pm gives the advantage of an optimal distribution and positioning within cement. In embodiments in which the additive is conductive, this promotes conductivity of the resulting cement or concrete. Thus, in embodiments of the invention, the biochar particles comprised in the additive may have an average diameter of less than about 200pm, less than about 150pm, less than about 120pm, less than about 110pm, less than about 100pm, less than about 75pm, less than about 50pm or less than about 25pm .

[0045] The additive according to the first aspect may further comprise carbon fiber .

[0046] The carbon fiber of the additive according to the first aspect may have a particle si ze of 10 to 15 pm x 230 to 270 pm, or 12 to 13 pm x 240 to 260 pm .

[0047] Carbon fiber, sometimes referred to as graphite fiber can include a combination of properties , such as high sti f fness , high tensile strength, low weight , high chemical resistance , high-temperature tolerance , and low thermal expansion, depending on the speci fic type and / or processes used to make the carbon fiber . Various methods can be used to produce the carbon fiber, provided that the fibers are electrically conductive . Carbon fiber is available in 3 primary forms , including continuous tow comprised of long, unbroken strands of carbon fiber , and are typically wound onto a spool , chopped carbon fiber usually comes in short lengths , and is commonly made from chopping continuous tow, and milled carbon fiber is very finely chopped and can be used as a filler to increase the conductivity, sti f fness , or other properties of a material . In one embodiment , the additive comprises carbon fiber in the form of chopped fiber .

[0048] The particle si ze of the carbon fiber may refer to the length of the largest dimension x the length of the second largest dimension . The largest dimension of the carbon fiber may refer to the diameter of the smallest sphere in which the carbon fiber would fit . The second largest dimension of the carbon fiber may refer to the diameter of the smallest sphere in which the carbon fiber would fit i f the largest dimension were ignored . For the avoidance of doubt, the sphere refers to a fictitious sphere .

[0049] The carbon fiber gives the added utility to the additive of improved conductivity of the cement wherein the additive is added. The inventors have surprisingly found that cement becomes conductive with as little as 0.1 wt.-% carbon fiber when carbon fiber is combined with the disclosed biochar. If only carbon fiber would be added to cement, 1 wt.-% carbon fiber would be needed to make the cement conductive. Thus, in embodiments of the invention, the additive comprises less than about 1 wt.-%, less than about 0.5 wt.-%, less than about 0.2 wt.-% or less than about 0.1 wt.-%. In certain embodiments, the additive comprises 0 wt.-% of carbon fiber.

[0050] The ratio of the biochar particles to carbon fiber of the additive according to the first aspect may be 10:1 to 1000:1, 20:1 to 500:1, 30:1 to 300:1, 50:1 to 100:1, or 60:1 to 90:1, or 70:1 to 80:1. In alternative embodiments, the additive may be free of carbon fiber.

[0051] The inventors have surprisingly found that the above ratio is the optimal balance between achieving the best conductive properties of the additive while maintaining low production costs and carbon footprint.

[0052] The biochar comprised in the additive may be in particulate form. In some embodiments, the biochar comprised in the additive according to the first aspect may comprise carbonized biomass. The carbonized biomass may be crushed.

[0053] The biochar particles of the additive may consist of carbonized biomass which has optionally been crushed.

[0054] Biomass may refer to organic matter. Crushed may refer to biomass that has been deformed through grinding, beating, crushing, etc. Carbonized may refer to biomass that has been converted into carbon or charcoal through heating, burning, fossilization or the like. The inventors have found that the use of biochar provides advantages over conductive carbon materials derived from other sources, for example the fossil fuel industry. For example, through the selection of biomass used to prepare the biochar, this will impact the properties of the biochar (for example the particle size and shape as well as the composition) , enabling the biochar to be tailored towards specific cement and concrete applications.

[0055] The biomass may comprise agricultural residues such as corncobs, sunflower shells and husks, and sugar cane bagasse; wood materials such as wood logs, slabs, chips, and bark; openwater plants such as water hyacinths and seaweed; organic municipal solid wastes, including tires, sewage sludge, or other organic clarified solids; and animal husbandry residues. In some embodiments, the biomass may comprise a fibrous material.

[0056] The wood or bamboo may be recycled wood or bamboo. It is beneficial both economically and environmentally to use recycled biomass.

[0057] The biomass of the additive according to the first aspect may comprise walnut shell, peach pits, pine pellets, olive pits, wood, bamboo, or a combination thereof. The biomass of the additive according to the first aspect may consist of walnut shell, peach pits, pine pellets, olive pits, wood, bamboo, or a combination thereof.

[0058] In one embodiment, the biomass of the additive comprises pine pellets. In one embodiment, the biomass of the additive consists of pine pellets.

[0059] The inventors have found that using pine pellets as the biomass is particularly good because the resulting biochar is strong and provide excellent electrical conductivity when used in cement additives.

[0060] The biochar particles of the additive according to the first aspect may comprise less than 20 wt.-%, or less than 15 wt.-%, or less than 10 wt.-% oxygen. The biochar particles may comprise 0 to 20 wt.-%, or 0 to 15 wt.-%, or 0 to 10 wt.-% oxygen .

[0061] The biochar particles of the additive according to the first aspect may comprise less than 10 wt.-%, or less than 8 wt.-%, or less than 5 wt.-% hydrogen. The biochar particles may comprise 0 to 10 wt.-%, or 0 to 8 wt.-%, or 0 to 5 wt.-% hydrogen.

[0062] The oxygen content of the biochar particles may be measured according to DIN 51733: 2016-04. The hydrogen content of the biochar particles may be measured according to DIN 51732: 2014-07.

[0063] It is desirable to obtain biochar particles that comprise minimal amounts of oxygen and hydrogen because the conductivity of the biochar is improved when the amount of oxygen and hydrogen is minimized.

[0064] The biochar particles of the additive according to the first aspect may comprise sulfur at an amount of less than 1 wt.-%, less than 0.5 wt.-%, less than 0.25 wt.-%, less than 0.2 wt.-%, less than 0.15 wt.-%, less than 0.1 wt.-%, less than 0.05 wt.-% or less than 0.03 wt.-%. The inventors have found that the use of carbon comprising significant levels of sulfur (e.g. in coke derived from the fossil fuel industry) can be problematic in conductive cement and concrete applications as the sulfur can form corrosive compounds which undermine the structure of those compositions, particularly if those composition comprise metal components .

[0065] Additionally or alternatively, the biochar particles comprised in the additives of the invention may have a surface area (BET) of at least about 50m2 / g, at least about 100m2 / g, at least about 150m2 / g, at least about 200m2 / g, at least about 250m2 / g, at least about 300m2 / g or at least about 500m2 / g. In certain embodiments, the biochar particles comprised in the additives of the invention may have a surface area (BET ) of about 100m2 / g to about 500m2 / g .

[0066] In one embodiment , the additive with biochar particles absorb water after a first period of time , allowing a larger water fraction to be used in the cement formulation and thereby providing for good workability characteristics . As the cement cures , water is reduced through the multiple chemical reactions occurring in the hydration process , creating a water deficiency in the mixture . As a result , water is drawn out of the biochar particles and provides continued moisture for hydration from inside of the curing body, leading to a material with superior strength .

[0067] The biochar particles may be manufactured according to conventional methods or according to the methods disclosed in the international patent application numbered W02023 / 152426 .

[0068] In one embodiment , the biochar materials produced need to be processed prior to use in a cement / concrete product . The biochar may be f irst reduced in si ze to a particular grade of biochar particles as discussed above , for example , a powder of biochar particles , then sorted into groupings , each with a predetermined si ze or range of si zes , and then combined into an additive comprised of a predetermined amount of one or more si ze groups . For example , the biochar may be milled in a rotary mill to create a powder that is processed through sieves of various si zes , such as sieves with openings of 50 microns , 100 micron, 200 micron and 500 microns . Only particles with a si ze less than 50 microns will pass through the 50 micron sieve , and so on . A powder can be processed with multiple sieves to make a material comprising a range of s i ze particles . For example an additive product can be made by us ing multiple sieves - i f a 100 micron sieve is used to produce a power that passes through that sieve with particles less than 100 microns , the resulting powder can be passed through the 50 micron sieve , yielding two separate powders: one with a size range of less than 50 microns and the other with a size range of particles less than 100 micron and greater than 50 microns.

[0069] Whether the biochar comprised in the additive is processed, e.g. milled, or not, in embodiments, the biochar may in particulate form.

[0070] In some embodiments, the particles of biochar may be granular in form, e.g. the average ratio between the longest dimension and the shortest dimension of the particles may range from 1 : 1 to 3 : 1. In such embodiments, the average length of the longest dimension of the granular particles may be from about 1pm to about 1000pm about 5pm to about 500pm, about 10pm to about 300pm or about 20pm to about 200pm.

[0071] In some embodiments, the particles of biochar may be elongate in form, e.g. the average ratio between the longest dimension and the shortest dimension of the particles may be greater than 3:1. In such embodiments, the average ratio between the longest dimension and the shortest dimension of the particles may be greater than 5:1, 7:1, 10:1, 15:1 or 20:1. Additionally or alternatively, the average length of the longest dimension of the elongate particles may be about 500pm to about 10000pm, about 1000pm to about 6000pm or about 2000pm to about 4000pm.

[0072] In another embodiment, an additive of biochar particles can be manufactured by combining 1 kilogram of powder that is less than 50 microns with 1 kilogram of powder that has particles between 100 and 200 microns.

[0073] In one embodiment, milling is used to refine the biochar into powder / particulate form. Milling is a fundamental process used in a variety of industries and involves reducing the size of solid masses, of a range of sizes, to achieve a predetermined range of particles that comprise the additive powder. Milling uses mechanical interactions between a milling media and the material being milled and / or between the material being milled itself. Some mechanisms include (1) Impact: Particles are broken due to collisions with the milling media or equipment, (2) Compression: Particles are squeezed and fractured under high pressure, (3) Shear: Particles are cut or torn apart by shear forces, and (4) Attrition: Particles are worn down by repeated collisions. The mechanism is dependent on the milling process chosen.

[0074] Some milling methods suitable for processing of biochar include:

[0075] 1. Rolling Mill. A common method used for reducing particle size. It involves the use of a rotating container filled with a milling media and the material to be milled. Milling media can be spherical or other shapes. Rolling mills are versatile and can be employed for both dry and wet milling processes .

[0076] 2. Jet Milling. Jet milling utilizes high-speed jets of gas or air to create particle-particle collisions, resulting in size reduction. It is particularly effective for reducing particles to sub-micron sizes.

[0077] 3. Hammer Milling. Hammer mills use rotating hammers to pulverize materials. They are suitable for both coarse and fine milling.

[0078] 4. Attrition Milling. Attrition milling involves the use of grinding media such as beads or balls within a stirred mill. The agitation causes particles to collide, leading to size reduction. It is employed in the production of fine and ultrafine powders.

[0079] The additive of the invention may be provided as part of a kit. In such embodiments, the additive may be comprised in a container. The kit may comprise instructions to combine the additive with cement powder or other components of concrete (e.g. aggregate, plasticizer, or one or more other concrete additives) to prepare a cement or concrete composition, optionally in accordance with the methods of the present invention as discussed herein. In certain embodiments, the kit of this aspect of the invention may comprise one or more grades of biochar, for example bulk biochar, biochar coarse aggregate, biochar fine aggregate, and / or biochar powder.

[0080] In one embodiment, the kit is provided in a form convenient to add to a ready-mix line. In one embodiment, a mixture of cement, fine aggregate, coarse aggregate, and / or other constituents is prepared and well mixed, followed by addition of the additive kit to complete the formulation. The kit may be constructed such that a predetermined amount of kit material is added for a specific mass of cement, fine aggregate, coarse aggregate, and / or other constituents. For example, 100 kg of kit may be specified to be added for each 1000 kg, and fraction thereof, of cement, fine aggregate, coarse aggregate, and / or other constituents prepared as ready-mix.

[0081] In one embodiment, the kit may comprise one, some or all of the materials listed in the following tables, optionally in the quantities detailed therein.

[0082] Overall Kit Composition

[0083] embodiment , the kit may comprise the following amounts of constituent components for use in poured concrete applications .

[0084] Poured Concrete Kit Composition

[0085] In one embodiment , the kit may comprise the following amounts of constituent components for use in mortor applications . Poured Concrete Kit Composition

[0086] According to a further aspect of the present invention, there is provided the use of the additive of the present invention as an additive for cement or concrete compositions.

[0087] Cement / Concrete

[0088] According to a second aspect, cement or concrete comprising the additive according to the first aspect is provided .

[0089] Cement according to the second aspect may comprise less than about 25 wt.-%, less than about 20 wt.-%, less than about 15 wt.-%, less than about 12 wt.-%, or about 9 to about 11 wt . - % of the additive. In certain embodiments, cement according to the second aspect may comprise less than about 15 wt.-% of the additive .

[0090] It has been found that when incorporating the above amount of an electrically conductive additive in the cement, the cement becomes electrically conductive. The above amount of the additive is the optimal balance between production cost and achieved conductivity. However, depending on the intended application of the cement composition, greater levels of the additive may be preferable. Thus, in certain embodiments, the cement composition may comprise at least about 25 wt.-%, at least about 50 wt.-% or at least about 75 wt.-% of the additive.

[0091] In embodiments of the invention, the cement composition may comprise (1) bulk biochar, (2) biochar coarse aggregate, (3) biochar fine aggregate, and / or 4) biochar powder.

[0092] In some embodiments, the cement composition may comprise about 0 wt-%. to about 90 wt-%. or about 5 wt-% to about 20 wt-% of bulk biochar.

[0093] In embodiments, the cement composition may comprise about 0 wt-%. to about 90 wt-%., about 5 wt-% to about 20 wt-% of biochar coarse aggregate.

[0094] In some embodiments, the cement composition may comprise about 0 wt-%. to about 50 wt-%., about 5 wt-% to about 30 wt-%, or about 10 wt-%. to about 20 wt-% of biochar fine aggregate .

[0095] In certain embodiments, the cement composition may comprise about 0 wt-%. to about 90 wt-%., about 5 wt-% to about 50 wt-%, or about 10 wt-%. to about 30 wt-% of biochar powder.

[0096] The cement composition of the invention may additionally comprise about 5 wt-% to about 80 wt-%, about 10 wt-% to about 60 wt-% or about 20 wt-% to about 40 wt-% cement powder .

[0097] In some embodiments, the cement composition may comprise about 0 wt-% to about 80 wt-%, about 10 wt-% to about 60 wt-% or about 20 wt-% to about 50 wt-% fine aggregate (e.g. sand)

[0098] In embodiments, the cement composition may comprise about 0 wt-%. to about 90 wt-%., about 5 wt-% to about 20 wt-% of coarse aggregate. In certain embodiments, the cement composition of the invention may comprise carbon fiber in an amount of about 5 wt- % or less, about 4 wt-% or less, about 3 wt-% or less, about 2 wt-% or less or about 1 wt-% or less. In some embodiments, the cement composition does not comprise carbon fiber.

[0099] In concrete compositions of the invention comprising the additive, this may be present in an amount of at least about 3%, at least about 5%, or at least about 10% by weight of the concrete composition. Additionally or alternatively, the concrete composition may comprise less than about 50 wt-%, less than about 30 wt-% or less than about 20 wt-% of the additive.

[0100] In embodiments of the invention, the concrete composition may comprise (1) bulk biochar, (2) biochar coarse aggregate, (3) biochar fine aggregate, and / or 4) biochar powder .

[0101] In some embodiments, the concrete composition may comprise about 0 wt-%. to about 90 wt-%., about 10 wt-% to about 50 wt-%, or about 20 wt-%. to about 40 wt-% of bulk biochar.

[0102] In embodiments, the concrete composition may comprise about 0 wt-%. to about 90 wt-%., about 10 wt-% to about 50 wt- % , or about 20 wt-%. to about 40 wt-% of biochar coarse aggregate .

[0103] In some embodiments, the concrete composition may comprise about 0 wt-%. to about 90 wt-%., about 10 wt-% to about 50 wt-%, or about 15 wt-%. to about 30 wt-% of biochar fine aggregate .

[0104] In certain embodiments, the concrete composition may comprise about 0 wt-%. to about 50 wt-%., about 5 wt-% to about 40 wt-%, or about 10 wt-%. to about 25 wt-% of biochar powder.

[0105] The concrete composition of the invention may additionally comprise about 5 wt-% to about 50 wt-%, about 10 wt-% to about 40 wt-% or about 20 wt-% to about 30 wt-% cement powder . In some embodiments, the concrete composition may comprise about 0 wt-% to about 60 wt-%, about 10 wt-% to about 50 wt-% or about 20 wt-% to about 40 wt-% fine aggregate (e.g. sand) .

[0106] In certain embodiments, the concrete composition may comprise about 0 wt-%. to about 90 wt-%., about 10 wt-% to about 50 wt-%, or about 20 wt-%. to about 40 wt-% of coarse aggregate.

[0107] In certain embodiments, the concrete composition of the invention may comprise carbon fiber in an amount of about 5 wt- % or less, about 4 wt-% or less, about 3 wt-% or less, about 2 wt-% or less or about 1 wt-% or less. In some embodiments, the concrete composition does not comprise carbon fiber.

[0108] According to one embodiment, cement compositions are provided that reduce the greenhouse gas (GHG) emissions of the installed material on a per-mass and per-volume basis. A significant amount of energy is used in the manufacture of cement and each ton manufactured contributes nearly 1 ton of carbon dioxide (930 kgs) to atmospheric emissions, due to CO2 from the required combustion of fossil fuel as well as CO2 tied to the process chemistry for clinker production. Cement is one of the largest single-sources of CO2 worldwide, due to high resource requirements and the sheer quantity used worldwide. As a result, substitution of even small quantities of the additive according to the first aspect into cement or concrete can be impactful with respect to carbon emissions. Incorporating the additive according to the first aspect into cement represents one method to reduce the net effective mass of emitted carbon dioxide by direct displacement of cement.

[0109] Cement is a binding material widely used in construction, possessing the ability to set, harden, and adhere to other materials when combined with water. This substance is a key ingredient in concrete, mortar, stucco, and grout. A table of the various types of cement are included in Table 1 below, and all are compatible with the invention described herein .

[0110] Table 1 : Types of Cement

[0111] The most common types of cement include the following, each of which is suitable for use herein and may befit from a modification of the GHG emissions profile, ability to heat and melt ice and snow, ability to provide heat for warming a structure, and the capability to be poured in low temperatures by modifying the temperature of the poured material through ohmic heating.

[0112] 1. Ordinary Portland Cement (OPC) : the most common type of cement worldwide. Manufactured by grinding limestone and clay, then heating them in a kiln at a temperature of about 1400-1500 Celsius. The produced substance, known as clinker, may be ground into fine powder and combined with a small amount of gypsum to control the setting time. Three primary grades: OPC 33, OPC 43, and OPC 53, based on the compressive strength.

[0113] 2. Portland Pozzolana Cement (PPC) : manufactured by combining OPC clinker with pozzolanic materials (such as fly ash, volcanic ash, or silica fumes) , in a proportion of up to 35%. Pozzolanic materials have the ability to react with calcium hydroxide released during the hydration of OPC and form cementitious compounds, leading to increased long-term strength and durability. PPC has low heat of hydration and is resistant to the attack of water, making it well suited for hydraulic structures .

[0114] 3. Rapid Hardening Cement: gains strength faster than OPC, due to the higher content of tricalcium silicate (C3S) . Despite the fast setting, this type of cement provides similar strength to OPC. 4. Sulphate Resisting Cement: made with a low proportion of tricalcium aluminate (C3A) , making it resistant to sulphate attack. This cement is ideal for use in foundations, piles, basements, and other structures exposed to sulphate-rich environments such as sewage treatment plants or coastal areas.

[0115] 5. White Cement: made from raw materials with a low content of iron and manganese, which give ordinary cement its grey color. Primarily used for decorative purposes in part due to high cost.

[0116] 6. Quick Setting Cement: increased setting times (compared to OPC) drive applications to underwater construction or cold weather conditions where early setting is desirable.

[0117] 7. Low Heat Cement: lower heat of hydration than OPC reduces the risk of thermal cracking in large concrete structures, making it useful for dams and other large volume concrete constructions.

[0118] 8. Blast Furnace Slag Cement: a combination of OPC clinker with granulated blast furnace slag that improves the cement's durability and resistance to chemical attacks.

[0119] The cement or concrete of the second aspect may comprise Ordinary Portland Cement (OPC) . The cement may consist of Ordinary Portland Cement (OPC) .

[0120] The cement or concrete according to the second aspect may further comprise less than 5 wt.-%, or less than 4 wt.-%, or less than 3 wt.-% fluidizers.

[0121] The cement or concrete according to the second aspect may further comprise less than 5 wt.-%, or less than 4 wt.-%, or less than 3 wt.-% of plasticizers.

[0122] The cement or concrete may comprise 0 to 5 wt.-%, or 0 to 4 wt.-%, or 0 to 3 wt.-% fluidizers.

[0123] The cement or concrete may comprise 0 to 5 wt.-%, or 0 to 4 wt.-%, or 0 to 3 wt.-% plasticizers.

[0124] The cement may be used in concrete. At the most basic level, concrete is a mixture comprising cement and aggregate, where the cement (relatively high value functional material, used in small fractions) serves to bind the aggregate (relatively low value, high volume filler) to create a monolithic structure at low costs. More specifically, concrete can include a binding phase, cement paste, additives and aggregates of various size. Thus, according to a further aspect of the present invention, there is provided a concrete composition comprising cement of the second aspect of the invention. The concrete may be electrically conductive.

[0125] As noted above, the additives of the invention (or cements or concretes comprising such additives) may comprise one or more different grades of biochar, for example bulk biochar, biochar coarse aggregate, biochar fine aggregate, and biochar powder. The versatility of the biochar additive permits it to be used to replace various components of cement and concrete compositions, thus reducing the carbon footprint of those compositions .

[0126] Such applications and end uses include cement mixes, mortars, concrete, nonstructural base materials, and others - all of which are encompassed by 'cement' or 'concrete' as those terms are used herein. Examples of the range of mass loadings of each biochar grade are as follows:

[0127] Overall exemplary composition

[0128] Exemplary concrete composition

[0129] Exemplary mortar composition

[0130] Exemplary non-structural cement base composition

[0131] Advantageously, signi ficant levels of biochar can be comprised within concrete compos itions . Thus , in embodiments of the invention, the concrete or cement compositions may comprise at least about 1 wt-% , at least about 2 wt-% , at least about 5 wt-%, at least about 10 wt-% or at least about 20 wt-% of the additive of the invention.

[0132] However, depending on the intended application of the concrete composition, greater levels of the additive may be preferable. Thus, in certain embodiments, the concrete composition may comprise at least about 25 wt.-%, at least about 50 wt.-% or at least about 75 wt.-% of the additive (or additives) of the invention.

[0133] In addition to providing the improvements discussed above, the use of the additive of the invention in cement and concrete composition provides a profoundly positive environmental impact.

[0134] Life Cycle Analysis (LCA) , also known as life cycle assessment, is an analytical computational method that is used to evaluate the environmental impacts of a product, reported as an equivalent amount of carbon dioxide (CO2) issued to the environment from production, no matter the actual source of environmental impact. The reported value represents the cumulative amount of carbon dioxide emitted to the environment during all phases of production, for all component materials and processes throughout a product life cycle. This includes all stages from raw material extraction, manufacturing, distribution, use, repair and maintenance, and finally to disposal or recycling. More information regarding the calculation of LCA values for cements and concretes, as well as components thereof, can be found in a paper by Hafez et al. Applied Sciences, 2019, 9, 4803, pages 1 to 26, and the specific values included in the LCA calculations proposed herein for nonbiochar components are taken from Table 4 of that document.

[0135] LCA Values for the materials comprising concrete are widely reported. Cement is the largest environmental impact, at 930 kg-CO2 per 1000kg cement, primarily due to the energy consumed during processing. Aggregate materials such as fine aggregate ( sand) and coarse aggregate ( rock) are lower, as a result of the limited processing steps required . The following analysis uses the mean reported value of 6 . 4 kg-CCt per 1000kg for fine aggregate and 11 . 5 kg-CCt per 1000kg for coarse aggregate . Plastici zer has an average reported value of 833 kg- CO2 per 1000kg . The LCA value for biochar produced by the applicant has been calculated as -3030 kg-CCt per 1000kg . This calculation was made using the Puro methodology by conducting i ) an independent cradle to gate calculation, and ii ) an internally prepared gate to grave calculation .

[0136] In some embodiments herein, cement or concrete compositions comprising the additive of the invention are provided that have a li fe cycle analysis ( LCA) lower than that of a comparator formulation in which the additive is not present . In some embodiments , the cement or concrete compositions of the invention have an LCA which is about 90% or lower, about 80% or lower, about 70% or lower, about 60% or lower or about 50% or lower than a comparator formulation which does not comprise the additive .

[0137] In certain embodiments , the cement or concrete composition of the invention has an LCA of zero kg of Carbon Dioxide equivalent ( kg-CO2_eq . ) . In other embodiments , the cement or concrete composition of the invention has an LCA of less than zero kg-CO2_eq .

[0138] The following tables compare a commercially available concrete composition and two concrete compositions of the invention having an LCA of less-than- zero kg of Carbon Dioxide equivalent ( kg-CO2_eq . ) .

[0139] Commercially available concrete :

[0140] Inventive Composition 1 Inventive Composition 2

[0141] Thus , as is apparent , the replacement of portions of cement with biochar powder and coarse aggregate with biochar coarse aggregate , respectively, has a profound impact on LCA, resulting in concrete compositions having less-than- zero kg of Carbon Dioxide equivalent ( kg-CO2_eq . ) .

[0142] In one embodiment , electrically conductive cement and concrete are provided that can be heated through in-situ resistance . Heated concrete allows snow and ice removal directly, with no need for equipment to be included within the installation . Direct heating of poured concrete can also provide the ability to install concrete in cold weather conditions by allowing the poured material to be heated above a minimum temperature and ensuring that the proper chemical reactions of the curing process occur, that may otherwise be inhibited due to the cold temperatures .

[0143] In some embodiments , concrete compositions are provided that comprise a mixture of cement and aggregate and at least 1 wt . -% of the additive according to the first aspect . The concrete compositions may comprise at least one active ingredient , that is capable of reacting within the mixture , after an initiation agent is added to the mixture , to form a structure that is stronger when compared to prior to the addition of the initiation agent . For example , in many cement formulations , water serves as the initiation agent, but may also comprise an acid, base, or other chemical.

[0144] In one embodiment, a cement or concrete formulation is comprised of concentrations of less than 25 wt.-% (or optionally less than 15 wt.-%) of the additive according to the first aspect and / or has an electrical resistance of less than 100 ohm-cm, while maintaining at least 80% of the compressive strength of the cement formulation when formed without the additive. In one embodiment, the final cured materials have an electrical conduction suitable for direct power dissipation to melt ice and snow with a power density of at least 100 watts per square meter of exposed poured surface area.

[0145] In certain embodiments, the cement or concrete composition of the invention has an improved ability to carry electrical current.

[0146] The ability of a material to carry electrical current is typically noted by conductivity (commonly represented by the Greek letter o (sigma) ) and / or resistivity (commonly represented by the Greek letter p (rho) ) . The SI unit of electrical resistivity is the ohm-meter (Q-m) and SI unit of electrical conductivity is siemens per meter (S / m) . The ohm (Q) is the measure of resistance and the Siemen (S) is the measure of conductance. Resistivity (p) is the inverse of conductivity (p = 1 / o) .

[0147] In certain embodiments, the cement or concrete composition of the invention has an electrical resistivity of about 1000 ohm-cm or less, about 750 ohm-cm or less, about 500 ohm-cm or less, about 250 ohm-cm or less, about 100 ohm-cm or less, about 75 ohm-cm or less or about 50 ohm-cm or less.

[0148] In some embodiments of the invention, the cement or concrete composition has a compressive strength at least about 80%, at least about 90%, at least about 100% at least about 105% or at least about 110% of the cement or concrete composition when formed without the additive .

[0149] The cement and concrete compositions according to the second aspect of the invention may have the following beneficial properties :

[0150] 1 . Electrical conductivity to provide strain sensing ability that can inform users of loads placed onto sections ;

[0151] 2 . Electrical interconnection to provide temperature sensing ability that can inform user of environmental conditions ;

[0152] 3 . Electrical resistance to provide damage sensing ability though reduction in the level of conductivity due to interruption from cracks , for stability monitoring; can be used for damage detection within a structure , which occurs under increasing stress even within the elastic regime . Reversible changes in electrical resistance relates to dynamic strain, irreversible changes in resistance relates to damage ;

[0153] 4 . Thermoelectric behavior for electrical generation or conversion;

[0154] 5 . Low power thermal ef fects to provide insulation properties for energy savings ;

[0155] 6 . Electrical conductivity for electrical management such as grounding source , anti-static / static dissipation, and / or facilitating cathodic protection of embedded steel ;

[0156] 7 . Resistive conduction properties of fully cured materials for direct heating of concrete for melting ice and snow;

[0157] 8 . Resistive conduction properties in newly poured materials to enable installation at lower temperatures ; and

[0158] 9 . Conductivity to provide interaction with radio waves for EMI management or lateral guidance in automatic highways .

[0159] 10 . Electrical resistance properties and monitoring of fractional changes in resistance during cyclic tens ion and compression to correlate with applied loads . The resistance increases reversibly upon tensile loading and decreases reversibly upon compressive loading.

[0160] 11. Enhanced compression strength of cement and concrete compositions .

[0161] 12. Corrosion protection for metal bodies, e.g. steel rebar provided within the cement or concrete compositions.

[0162] A method for producing cement or concrete

[0163] According to a third aspect, a method for producing cement or concrete is provided, the method comprising: a. providing a mixture comprising one or more cement powders and the additive according to the first aspect ; b. adding water to the mixture to obtain an aqueous mixture ; c. adding the aqueous mixture to a form; and d. curing the aqueous mixture.

[0164] It should be understood that the mixture of compounds to form materials herein may be provided in any suitable manner. For example, base materials comprising the cement powder, such as those containing calcium, silicon, aluminum, and others may be provided in any suitable ratio to provide a desired final product, and are not limited to any published or other documented formulations for a given type of cement.

[0165] In embodiments, in step a., the one or more cement powders may be mixed directly with the additive. Steps b. to d. may then be performed to provide a cement composition.

[0166] For the avoidance of doubt, where reference is made in step a. to the provision of a mixture comprising one or more cement powders, the mixture may be dry, e.g. the one or more cement powders may be provided in dry form. Alternatively, the one or more cement powders may be present in a moist mixture comprising water.

[0167] Alternatively, other concrete components (e.g. plasticizer, fine aggregate (e.g. sand) , coarse aggregate and / or one or more other concrete additives) may be mixed with the additive before being combined with the one or more cement powders in step a. (optionally before and / or after step b.) to provide a concrete composition.

[0168] Still alternatively, the one or more cement powders may be mixed with other concrete components (e.g. plasticizer, fine aggregate (e.g. sand) , coarse aggregate and / or one or more other concrete additives) before being mixed with the additive.

[0169] In alternative embodiments, the additive may be mixed with one or more other concrete components (e.g. plasticizer, fine aggregate (e.g. sand) , coarse aggregate and / or one or more other concrete additives) and the resulting mixture, comprising the additive, is then mixed with one or more cement powders to provide the mixture in step a. of the process of the invention. In such embodiments, the additive may be mixed with one or more concrete additives (e.g. aggregate or plasticizer) and the mixture obtained in step a. may subsequently be mixed with other concrete components.

[0170] In embodiments of the invention, the mixture provided in step a. of this aspect of the invention may be homogenous. In certain embodiments, the mixture provided in step a. may be heterogeneous .

[0171] In embodiments the additive may comprise differing grades of biochar (e.g. bulk biochar, biochar coarse aggregate, biochar fine aggregate, and / or biochar powder) . In certain embodiments, a plurality of additives (e.g. 1, 2, 3, 4 or more than 4) additives may be used in the process of the invention, with some or all of the additives comprising differing grades of biochar. In step b. of the process of the invention, water is added to the mixture. In embodiments, the water may comprise additional components, for example basifying agents such that the water has a pH greater than about 7, greater than about 8 or greater than about 9. Additional or alternative additional components may also be comprised in the water.

[0172] In some examples, the mixture of compounds may be in any suitable form. For example, compounds including, but not limited to those containing calcium, silicon, aluminum, and others may be in any suitable form of any particle size. The compounds comprising the cement fraction may be modified in size and / or shape along with the additive materials or separately from the additive materials or a combination thereof.

[0173] Any suitable material may be used, including naturally occurring materials, limestone, clay, silica fume, and fly ash blast furnace slag, and iron oxide from iron / steel processing. In yet further examples, waste oxides, such as calcium hydroxide and / or calcium oxide may be used from waste sources. The amounts of each of the materials within the mixture may be chosen based on the desired final cement composition. The cement industry frequently reports the composition of cement as a fraction (or percentage) of the raw material oxides as CaO, SiCt, AI2O3, and Fe2Oa instead of as the final compounds formed as a result of, and after, the curing process.

[0174] In step b . , the water added to the mixture obtained in step a. may be liquid water. The water may comprise further components, e.g. alkaline materials or acidic materials to provide an acidic or basic pH. Alternatively, the water may be present as a component in a moist mixture comprising either the one or more cement powders or the additive (in either embodiment, steps a. and b. would be conducted simultaneously) or one or more other concrete components. In embodiments, the aqueous mixture may be cured for a period of at least about 24 hours. The aqueous mixture may be cured at ambient conditions.

[0175] In alternative embodiments in which the cement is electrically conductive, the aqueous mixture may be cured by applying electricity to the aqueous mixture causing it to be heated and thus shortening curing duration. The inventors have advantageously found that through the inclusion of an electrically conductive additive, the electrical curing of the aqueous cement or concrete mixture results in the rapid heating, minimizing the formation of cracks, fissures or other points of weakness which can be observed with other rapid-curing techniques. Additionally, heat is applied uniformly throughout the cement or concrete body - which is an improvement from existing rapid-curing techniques in which cement / concrete bodies are exposed to heated air or steam which heats those bodies from the outside in, causing temperature differentials. A further advantage of this embodiment of the present invention is that it permits cement or concrete compositions to be conveniently and rapidly cured when formed and poured in cold weather environments.

[0176] Thus, in embodiments of the invention, the additive is electrically conductive, and in step d., curing is achieved by applying an electrical current to the aqueous mixture causing it to be heated. In such embodiments, the aqueous mixture is heated to a temperature of about 40°C to about 150°C, about 50°C to about 100°C, or about 60°C to about 80°C.

[0177] In embodiments in which the cement or concrete comprises metallic bodies, e.g. steel rebar, curing of the cement or concrete may be achieved by applying electrical current to those bodies. In such embodiments, the metallic bodies may comprise connection means to electrically connect the metallic bodies to a source of electrical current. In some embodiments , the provision of the composition comprising one or more cement powders and the additive according to the first aspect may comprise combining the one or more cement powders and the additive according to the first aspect to provide a first mixture and mixing the first mixture to obtain a mixture which is optionally homogenous .

[0178] In certain embodiments , additional steps may be conducted in the process of the present invention . For example , the aqueous mixture may be subj ected to a settling step, e . g . where the aqueous mixture is manipulated to remove air bubbles and / or ensure uni form settling of the mixture in a mold or similar . The settling step may comprise sonication, vibration or the like . The settling step may be conducted after step b . , after step c and / or before or during step d .

[0179] There are many applications for the cement and concrete materials described herein . In one embodiment , the additive according to the first aspect is used to increase the electrical conductivity of a cement formulation used in the manufacture of precast concrete blocks . The increase in conductivity allows ohmic heating to be performed directly within the concrete block .

[0180] Heating concrete in a precast manufacturing facility can be done to accelerate the production process . The proces s typically involves controlling the temperature conditions during the curing phase of concrete , which helps to increase its strength development and reduce the time required for it to gain the desired properties . Typically, heating is performed after the concrete is poured into a precast mold . This occurs after mixing of concrete ingredients , including cement , aggregates , water, and any additives or admixtures required for speci fic properties , followed by mold preparation where molds or formwork are prepared based on the desired shape and dimensions of the precast element . The molds can be made of steel , timber, or other materials .

[0181] Once the concrete is poured into the mold or formwork, it is set aside for curing, where heating can quicken the process . The concrete mixture is poured into the molds ensuring complete filling and proper compaction to eliminate any voids or air pockets . During the curing process , the concrete gradually gains strength and durability over time . Curing typically involves maintaining suitable temperature and humidity conditions to facilitate proper hydration of cement and the formation of strong bonds within the concrete . To speed up the curing process , heating is introduced . Various methods can be used to apply heat , depending on the facility ' s setup and requirements . Some common techniques include : Steam curing, where steam is circulated around the precast elements to increase the temperature and accelerate the hydration process . Hot water curing, which is similar to steam with precast elements being submerged in hot water tanks or sprayed with hot water to elevate the temperature and enhance the curing process . Electric or gas heating that use heating elements or gas burners to raise the temperature and maintain a consistent environment within the curing chamber . Each of these has proven to improve throughput in a manufacturing facility but are relatively inef ficient and / or slow due to the fact that heating is driven from the outside of a concrete body . In an embodiment of the invention, heating may be performed by applying an electrical current directly to the concrete body and heat is generated internally through ohmic heating . The ohmic heating is uni form and can be fast due to the fact that high temperature uni formity does not lead to cracks , typically found when concrete is heated unevenly . Direct electrical heating as disclosed herein provides a solution for many types of concrete being formed, including over a wide range of sizes and shapes of precast elements.

[0182] The inventors have identified that a further advantage of the inclusion of biochar in cement and concrete compositions is that the biochar imparts a protective effect on metal components comprised within the cement or concrete compositions such as metallic bodies e.g. steel rebar. Without wishing to be bound by theory, it is believed that this protective effect is achieved by cathodic protection, e.g. electrically conductive biochar comprised in the additive (or the cement / concrete composition) serves as a sacrificial material. Thus, in embodiments of the invention, the cement or concrete compositions of the invention, or the cement or concrete compositions obtainable from the methods disclosed herein, may comprise one or more metal components, for example one or more metallic bodies, e.g. rebar.

[0183] Conventional additives for cement may comprise only carbon fiber. Figure 1 illustrates a cement section (100) that is comprised of a cement (110) matrix and carbon fiber (120) . The electrically conductive cement material may be comprised of approximately 98 wt.-% of a standard mixture of ordinary Portland cement (OPC) , cement (110) , and 2 wt.-% of carbon fiber (120) . The carbon fiber (120) may be included in sufficient quantity and the mixture may be processed in such a way that the carbon fiber (120) forms a percolation network from location A (130) to location B (140) .

[0184] Figure 2 shows a cement section (200) of electrically conductive cement material comprised of a cement matrix (210) and a mixture of biochar particles (222) and carbon fiber (220) . The electrically conductive cement (200) may be comprised of approximately 85 to 90 wt.-% of a standard mixture of ordinary Portland cement (OPC) , cement (210) , and 10 to 15 wt.-% a mixture of biochar particles (222) and carbon fiber (220) . The mixture of biochar particles (222) and carbon fiber (220) may be included in sufficient quantity and the overall composite mixture may be processed in such a way that the mixture of biochar particles (222) and carbon fiber (220) form a percolation network from location A (230) to location B (240) . Preferably, the mixture of biochar particles (222) , and carbon fiber (220) are included in sufficient quantity and the mixture is processed in such a way that the biochar particles (222) and carbon fiber (220) form a percolation network throughout the entire cement section (200) such that electricity can be conducted from any point on the surface or in the interior of the cement section (200) to any other point on the surface or in the interior of the cement section (200) .

[0185] The percolating network throughout the entire cement section (200) may be comprised of a combination of contact between the conductive carbon materials within the OPC matrix. Preferably, the amount of carbon fiber used in a cement or concrete product is minimized, due to the high costs of carbon fiber .

[0186] Inter-material contact points (224) between biochar particles (222) and carbon fiber (220) may serve to reduce the overall amount of carbon fiber (220) required to yield a suitably conductive cement composite material. Preferably, the resistance to conduction measured from any point on the surface or in the interior of the cement section (200) to any other point on the surface or in the interior of the cement section (200) is less than 500 ohms per cm, more preferably less than 250 ohms per cm and most preferably less than 100 ohms per cm.

[0187] EXAMPLES

[0188] Example 1 - Production of additive with biochar - cement The following materials were used to create a solid cement test cube comprised of Ordinary Portland Cement (OPC) with Chopped Carbon Fibers (CCF) and dry durable carbon, i.e. biochar, with a Water to Cement ratio (w:c) = 0.4, where wt.-% additive is calculated from the dry weight of the OPC.

[0189] Weight of OPC = 570g

[0190] Weight of Water = 228g

[0191] Weight of Chopped Carbon Fibers = 1.1g

[0192] Weight of biochar = 28.5g

[0193] A dry mixing technique was used. Ordinary Portland cement (OPC) and half of the carbon fiber and biochar were combined and placed into rotary mill containers. The containers were then sealed and rotated on mill for 24-48 hours. 24 hours was sufficient to achieved dispersion of the the carbon fiber and dry durable carbon in the OPC.

[0194] All of the water was added to a medium sized beaker. The remaining half of chopped carbon fibers and dry durable carbon were added to water and stirred briefly by hand to properly wet the fibers + dry durable carbon. The fibers were chopped in bundled form, so they were unbundled using a sonicator. The mixture was sonicated for five minutes.

[0195] The OPC / fiber blend was added into a low shear mixer. The water / chopped carbon fibers were poured into the mixer and mixed for a couple of minutes until the consistency of the mixture looked even.

[0196] Cube molds were prepared and placed in a cube mold holder on a vibratory table and secured. The vibratory table was used to cause trapped air within the material to rise to the surface and escape, leading to a higher quality sample. The vibratory table also caused the materials in the mold to settle into a stable form that had an improved density compared to samples that are not subject to vibration. The vibration frequency can be from 10 hertz to over 10,000 hertz.

[0197] Once mixing was completed, the mix was slowly poured into the cube molds. The cubes were filled in thirds. The vibratory table was turned on to remove air bubbles from the mixture while poured. The mixture was vibrated until there were no more bubbles coming out of the mixture. The next third of the mixture was added and the process repeated. The mixture was vibrated for the entirety of the filling step.

[0198] Once the cubes were filled and de-bubbled, the top of the cubes were gently smoothed off to remove excess material.

[0199] The cubes were placed into a humidity chamber set at 93+% humidity and cured in the chamber for 24 hours. The cubes were then removed from the chamber and the cubes were removed from the molds.

[0200] The cubest were then placed into a temperature-controlled limestone water bath maintained at 23°C + / - 3° until ready for testing (e.g. after 3, 7, 14 days) .

[0201] Example 2 - Preparation of Conductive Cement

[0202] A series of solid cement test cube samples were prepared as follows. In total, nine samples were made, comprising a combination of 0%, 2.5% or 5% biochar, with 0.5%, 0.25% or 0.125% carbon fiber.

[0203] All of the samples used Ordinary Portland Cement (OPC) as the cement fraction and biochar made from compressed pine pellets. The biochar was processed in a 20cm diameter x 30cm wide ball mill for 24 hours at a rate of 30 revolutions per minute, using 20 stainless steel balls of 18mm diameter and a loading of approximately of full capacity. After milling, the biochar was collected for use after it was passed through a 106- micron screen while being vibrated at a frequency of 50-100 Hz to facility movement of suitable particles through the screen.

[0204] The Water to Cement ratio (w:c) for all samples was 0.4, where wt.-% of water and additive is calculated from the dry mass of the OPC .

[0205] Mass of materials was determined as followed:

[0206] Mass of OPC = 600g

[0207] Mass of Water = 240g

[0208] Mass of biochar (0%) = 0g

[0209] Mass of biochar (2.5%) = 15g

[0210] Mass of biochar (5%) = 30g

[0211] Mass of carbon fiber (0.125%) = 0.75g

[0212] Mass of carbon fiber (0.25%) = 1.5g

[0213] Mass of carbon fiber (0.5%) = 3g

[0214] Sample materials were then prepared for mixture by combining dry materials for a given sample, including OPC, and carbon fiber, along with biochar for 6 of the samples, while 3 of the samples did not contain biochar additive. Materials, except for the water, were combined and mixed on the rolling mill described above for 120 minutes, without stainless steel balls. Next, the mixture of materials was placed in a small- scale cement type rotary mixer and the water was added, and mixing began. Rotation was set to 30 revolutions per minute and mixed for 5 minutes. After mixing, the consistency of the mixture looked well mixed. The material was placed into 50mm cube molds, along with two copper wire leads that were inset into the molds at opposing apexes, such that the wires were approximately separated by 65 mm of cement sample. The copper leads wires were 1.5 mm diameter and contained 26 individual strands that were separated to make maximum contact with the wet cement mixture . After pouring, the cube molds were placed on a vibratory table for 20 seconds , operating at approximately 1000 Hz . Samples were cured in a humidity chamber set at 93+ % humidity for 24 hours , after which they were removed from the chamber and removed from the cube molds . After 24 hours , the conductivity of the samples was assessed and the results are shown in Figure 3 .

[0215] As can be seen, the inclusion o f increasing amounts of biochar decreased resistance , i . e . increased conductivity, for all levels of carbon fiber .

[0216] Depending on the applications of conductive cement and concrete , a suitable electrical resistance ( and the corresponding conductivity) can advantageously be achieved . The value of resistance can be measured using techniques known to those skilled in the art . In embodiments of the invention, resistance can be measured by incorporating conductors within the cement / concrete sample and measuring resistance between any 2 such conductors . The resistance is a function of the amount of cement lying between the 2 electrodes , and is represented as a resistance per centimeter of cement . It is important for the electrodes to have suf ficient surface area such that the electrode contacts the cement sample suitably . In the examples below, copper wire conductors were used to measure resistance . The copper lead wires were 1 . 5 mm diameter and contained 26 individual strands of 0 . 25mm that were separated to make maximum contact with the wet cement mixture . The wires were inserted the full 50mm depth of the sample cubes , providing a total contact surface area of : 26 * (pi * 0 . 25mm * 50 mm) = 1021 mm2= 10 . 21 cm2per electrode .

[0217] Preferably, at least 0 . 25 watts of power can be introduced into a 50mm cube sample when 20 volts is applied across the electrodes . More preferably, at least 0 . 5 watts of power can be introduced into a 50mm cube sample when 20 volts is applied across the electrodes . Most preferably, at least 1 watt of power can be introduced into a 50mm cube sample when 20 volts is applied across the electrodes .

[0218] Further, the data shows that an acceptable conductivity can be achieved using very low levels of carbon fibre , thus reducing the cost and carbon footprint of the conductive cement composition . This is particularly striking as the conventional view is that , in order to attain a viable level of conductivity in a cement composition, the composition would require carbon fiber to be included at a level of at least about 1 % by weight .

[0219] Example 3 - Preparation of Net-Zero-Carbon Concrete

[0220] A series of solid cement test cubes having a Net-Zero- Carbon value were prepared in accordance with the method described below .

[0221] The samples used Ordinary Portland Cement ( OPC ) as the cement fraction and two types of biochar :

[0222] ( 1 ) a first biochar "pine pellet biochar powder" made from compressed pine pellets . This biochar was processed in a 20cm diameter x 30cm wide ball mill for 24 hours at a rate of 30 revolutions per minute , using 20 stainless steel balls of 18mm diameter and a loading of approximately of full capacity . After milling, the biochar was collected for use after it was passed through a 106-micron screen while being vibrated at a frequency of 50- 100 Hz to facilitate movement of suitable particles through the screen .

[0223] ( 2 ) a second biochar "walnut shell biochar aggregate" made from walnut shells . This biochar was processed in a twin-roller mill with 5cm milling cylinders running at between 50 and 100 revolutions per minute . The walnut shells are passed through the mill with a 4mm gap between the rollers , followed by passing this milled walnut shell through a second time , with a 0 . 5mm gap between the rollers . After milling, the biochar was first passed through a 2000-micron screen while being vibrated at a frequency of 50- 100 Hz to facility movement of suitable particles through the screen and the fraction passing through the screen was collected for further processing, while the fraction that did not pass through the screen was set aside and not used in the sample . The fraction passing through the 2000-micron screen was then sieved with a 100-micron screen while being vibrated at a frequency of 50- 100 Hz to facility movement of suitable particles through the screen; this step is used to remove smaller particles that pass through the 100-micron screen, while the fraction that does not pass through the 100-micron screen is used as the walnut shell biochar aggregate .

[0224] The Water to Cement ratio (w : c ) was 0 . 5 , where wt . -% of water .

[0225] For the samples prepared comprising the "walnut shell biochar aggregate" , Dynamon Easy 11 plastici zer was used as a mixing and plastici zing agent .

[0226] Dynamon Easy 11 is a modi fied acrylic-based plastici zer for ready-mixed concrete available from Mapei of Milan, Italy .

[0227] The pine pellet biochar powder additive is calculated from the dry mass of the OPC . The walnut shell biochar aggregate additive is calculated from the dry mass of the Fine Aggregate , shown as followed .

[0228] Samples having the following compositions were prepared : The reference sample comprised no biochar component . The 'Only PR' sample comprised pine pellet powder (biochar PP ) as a partial cement replacement , and the ' 5%WS ' and ' 10%WS ' samples also included pine pellet powder as well as walnut shell fine aggregate (biochar WS ) as a partial replacement for conventional aggregate , at levels of 5% and 10% respectively .

[0229] The materials were then prepared for mixture by first combining the plastici zer with a small amount of the water to form a plastici zer premixture . Next , aggregate materials are combined with the walnut shell biochar aggregate (where present ) and mixed until well mixed to prepare an aggregate dry premixture .

[0230] Next , the OPC and pine pellet biochar powder is placed in a cement / concrete type rotary mixer and the mixer is rotated at 30 to 40 revolutions per minute . After 10 minutes of dry mixing, the remaining water was added, followed by addition of the plastici zer premixture . After 2 minutes the aggregate dry premixture is added to the mixer . Rotation continued at 30-40 revolutions per minute for 10 minutes . After mixing, the consistency of the mixture looked well mixed . The material was placed into 150mm cube molds .

[0231] After pouring, the cube molds were placed on a vibratory table for 20 seconds , operating at approximately 1000 Hz , to reduce air pockets within the sample cube . Samples were cured in a humidity chamber set at 93 + % humidity for 7 days , after which they were removed from the chamber and removed from the cube molds .

[0232] Samples made according to this method were destructively tested for strength and the results are shown in Figure 4 . Unexpectedly, all samples showed an a compression strength corresponding to or greater than the control sample made without biochar . This is a surprising finding as the expectation would have been that replacing functional components of cement and concrete with inert biochar would have negatively impacted compressive strength.

[0233] The following table shows the LCA values for the tested samples. For each component, LCA (CO2 / Component) is calculated by dividing the quantity of the component by the calculated CO2 emissions per ton for that material.

[0234] Thus, as is apparent from the 'Only PP' sample, the replacement of only a minor amount of cement powder with biochar powder results in a substantial reduction in LCA value. Further, as can be seen from the '5%WS' and '10%WS' samples, the replacement of modest amounts of concrete aggregate with biochar aggregate is sufficient to render the obtained concrete carbon negative .

[0235] Example 4 - Production of Conductive Cement Free of Carbon Fiber

[0236] The following materials were used to create a solid cement test cube comprised of Ordinary Portland Cement (OPC) and dry durable carbon comprising bamboo biomass as the feedstock, i.e. biochar manufactured using chopped bamboo fragments, with a Water to Cement ratio (w:c) = 0.4, where wt.-% additive is calculated from the dry weight of the OPC.

[0237] Weight of OPC = 600g Weight of Water = 240g

[0238] Weight of dry durable carbon = 30g

[0239] A screening technique was setup to sheer bamboo biochar fragments between a 140-mesh screen and a 60-mesh screen while applying light pressure , until fibrous materials were separated from the starting bamboo biochar fragment . These fibrous fragments were further separated by gently rolling between two cylindrical shaped rolling surfaces of 1 . 5cm diameter . After separation, fibrous materials were collected after they passed through a 60-mesh screen while being vibrated at a frequency of 50- 100 Hz to facility movement of suitable particles through the screen, until the 30-gram sample was collected .

[0240] The OPC and fibrous biochar material was combined and mixed on the rolling mill described above for a limited amount of time of 30 minutes . The reduced time served to ( 1 ) reduce potential damage to the fibrous fraction, and ( 2 ) create a suitably well- mixed material because the fibrous fraction was well separated in previous process steps as described, and did not need further separation .

[0241] Next , the OPC / fibrous biochar mixture was placed in a small-scale cement type rotary mixer and the water was added, and mixing began . Rotation was set to 30 revolutions per minute and mixed for 5 minutes . After mixing, the consistency of the mixture appeared even . The material was placed into 50mm cube molds , along with two copper wire leads that were inset into the molds at opposing apexes , such that the wires were approximately separated by 65 mm of cement sample . The copper leads wires were 1 . 5 mm diameter and contained 26 individual strands that were separated to make maximum contact with the wet cement mixture .

[0242] After pouring, the cube molds were placed on a vibratory table for 20 seconds , operating at approximately 1000 Hz . Samples were cured in a humidity chamber set at 93+ % humidity for 24 hours , after which they were removed from the chamber and removed from the cube molds . After 24 hours , the samples showed a resistance of approximately 400 ohms between the wire leads . Strikingly, conductivity was observed despite the absence of carbon fiber .

[0243] Example 5 - Strength Testing of Cement Compositions

[0244] Cement compositions were prepared broadly in accordance with Example 2 comprising cement powder and either 0% biochar, or increasing amounts of pine pellet biochar from 5 to 15 wt-% . The compression strength of those compositions was then tested and the results are shown in Figure 5 .

[0245] As can be seen, the inclusion o f biochar in the cement compositions resulted in either no signi ficant reduction in compressive strength of the compositions , or, advantageously, an increase in compressive strength .

[0246] This finding was completely unexpected as the addition of an inert material such as biochar into cement compositions would have been expected to have no impact on compressive strength, or, i f anything, a negative impact on strength .

[0247] Example 6 - Preparation of Nonstructural Cement Base

[0248] A non-structural cement base composition having a carbon value signi ficantly below zero was prepared in accordance with the method described below .

[0249] The sample has two ingredients : Ordinary Portland Cement ( OPC ) as the cement fraction and one type of biochar :

[0250] ( 1 ) Ordinary Portland Cement ; and ( 2 ) Biochar coarse aggregate material "walnut shell biochar coarse aggregate" made from walnut shells . This biochar was made in accordance with the methods disclosed in W02023 / 205081 , from walnut shell fragments received from a walnut processing facility . Biochar shell fragments were passed over a 1000-micron screen while being vibrated at a frequency of 50- 100 Hz to facilitate movement of suitable particles through the screen; thus removing smaller particles that pass through the 1000-micron screen, while the fraction that does not pass through the 1000-micron screen was retained and used as the walnut shell biochar coarse aggregate .

[0251] 750 kilograms of walnut shell biochar coarse aggregate was combined with 250 kilograms of Ordinary Portland Cement and placed into a v-blender . The v-blender is rotated at 30-40 revolutions per minute for a period of 1 hour .

[0252] Example 7 Field Test

[0253] A structure comprising electrically conductive concrete stairs was constructed using a concrete formulation of the present invention, comprising a pre-mixed concrete product , comprising fine aggregate , coarse aggregate , and cement powder . The concrete al so comprised biochar powder, biochar fine aggregate and carbon fiber . Within the body of the stairs , steel rebar was arranged to serve as electrodes to provide a contact point to deliver electrical power to the concrete composition making up the stairs and also to provide structural support to the stairs .

[0254] The structure had 5 individual steps , with the f irst 4 being identical in design and the fi fth being extended to provide a platform for entry into the building, as shown in Figures 6A and 6B . Each stair has a height of 105 mm and a width of 1 , 100 mm, providing an elevation rise to the fi fth step surface of 525 mm above ground level . The first four stairs have a tread depth of 400 mm, and the last stair has a depth of 2 , 600 mm to provide a large , flat platform surface for easy entry through the doorway, as shown in Figure 6B Structural support under stairs

[0255] 2 through 5 was provided by compacted gravel .

[0256] Ready mix bagged concrete ( Fescon Dry Concrete S 100 , 25 kg bags ) was used along with two conductive biochar additive materials ( a "biochar powder" and a "biochar fine aggregate" ) fabricated by Carbo Culture from pine wood pellets and walnut shells in accordance with the process disclosed in International Patent Publication No . WO2023 / 152426 and commercial ly sourced carbon fiber .

[0257] The carbon fiber, sold under the Trade Name ZOLTEK™ PX35 Type 02 - 6mm CARBON FIBER and manufactured by Zoltek Corporation, 3101 McKelvey Rd, Bridgeton, MO 63044 USA, was acquired directly from the manufacturer . Prior to use, the carbon fiber was processed by soaking in isopropyl alcohol and drying at 80 ° C .

[0258] To fabricate the stairs , a first step mold was created from wood planks , shaped to create the desired si ze . Holes were drilled into the sides of the forms of a si ze between 9- 10 mm in diameter to allow for an easy pass through of 7 mm diameter rebar . For steps 1 through 4 , a total of 6 rebar was placed into each form, with 3 rebar near the top of the step form and

[0259] 3 near the bottom, forming 3 pairs of rebar that will serve as electrodes . Spacing between each rebar of a pair was approximately 75 mm and spacing between the pairs was approximately 150 mm, spaced evenly across the 400 mm tread depth of a stair . Forms are constructed so that they may be removed from the mold after the concrete cures , as is known in the art of concrete structures and fabrication . The top step, with extended tread depth of 2 . 6 meters , had the electrodes running along the tread depth . A total of 8 pairs of rebar was used in the top step, with spacing between each rebar of a pair of approximately 75 mm and spacing between the pairs was approximately 110 mm, spaced evenly across the 1 , 100 mm width of the stairs . As with the lower stairs , the form was constructed so that it may be removed after the concrete cures .

[0260] The ingredients prepared as noted above were combined, according to the formulation presented in the following table , into a 150 - 180-liter rotary cement mixer . Typically, 2 to 4 bags of concrete , and proportional amounts of biochar powder, biochar fine aggregate , carbon fiber, and water, were mixed per pour . Working time of the concrete is stated by the manufacturer as 2-hours , allowing plenty of time to prepare appropriate volumes to pour a single step . Water was the last ingredient to be added, and mixing begins immediately after the water is added . Rotation was set to 30 - 35 revolutions per minute and mixed for 12 minutes . After mixing, the material was poured into the step mold . The poured product was finished by leveling the product to the surface of the form, smoothed with a trowel , and finished with a concrete brush .

[0261] Concrete Formulation : Thirty volts DC was applied across each of the 3 rebar electrode pairs of stair number 4 . Current monitoring with a Fluke 301D clamp-on current meter indicated 6 amps per electrode pair . The temperature climbed as the power was dissipated within the poured product and reached 38 C after approximately 1 -2 hours . The temperature was measured with an FLIR Brand model C5 infrared thermal camera . An image of the heated step can be seen in Figure 7 . Notably, as can be seen, heating of the step is uni form and not centered or limited to the locations at which the rebar is positioned, confirming that electrical energy not only passed through the conductive rebar, but was dissipated evenly throughout the concrete formulation permitting it to be heated evenly .

[0262] The table below shows a carbon footprint analysis of the poured product as described herein . Where available , emission values from the manufacturer were used . Where not available , industry averaged values based on published literature were used . As can be seen in the following table , the LCA for the product in the fabricated stairs is - 13 . 5 kg C02 per Ton of product . Thus , strikingly, not only does the composition of the invention permit the production of functional ( i . e . conductive and heatable ) cement and concrete forms , these have a negative carbon footprint .

[0263]

Claims

CLAIMS1. An additive for cement or concrete, the additive comprising biochar particles (222) .

2. The additive according to Claim 1, wherein the biochar particles (222) comprise at least 85 wt.-% carbon.

3. The additive according to Claims 1 or 2, wherein more than 60%, or more than 70%, or more than 80% the biochar particles (222) have a particle size of less than 110 pm.

4. The additive according to any preceding claims, wherein the additive further comprises carbon fiber (220) .

5. The additive according to Claim 4, wherein the carbon fiber (220) has a particle size of about 10 to 15 pm x 230 to 270 pm, or 12 to 13 pm x 240 to 260 pm.

6. The additive according to claim 4, wherein the carbon fiber (220) has a length of about 500pm or greater, about 5000pm or greater or about 20000 pm or greater.

7. The additive according to any one of Claims 4 to 5, wherein the ratio of biochar particles (222) to carbon fiber (220) is 50:1 to 100:1, or 60:1 to 90:1, or 70:1 to 80:1.

8. The additive according to any preceding claims, wherein the biochar particles (222) comprise crushed carbonized biomass.

9. The additive according to Claim 8, wherein the biomass comprises walnut shell, peach pits, pine pellets, olive pits, wood, bamboo, or a combination thereof.

10. The additive according to any preceding claims, wherein the biochar particles (222) comprise less than 20 wt.-%, or less than 15 wt.-%, or less than 10 wt.-% oxygen.

11. The additive according to any preceding claims, wherein the biochar particles (222) comprise less than 10 wt.-%, or less than 8 wt.-%, or less than 5 wt.-% hydrogen.

12. The additive according to any preceding claim wherein the additive is electrically conductive.

13. Cement (200) comprising the additive of any one of the preceding claims.

14. Cement comprising the additive in a concentration of less than 25 wt.-%.

15. The cement (200) according to claim 13 or 14, wherein the cement (200) comprises less than 20 wt.-%, 15 wt.-%, 12 wt . - % , or 9 to 11 wt.-% of the additive.

16. The cement (200) according to Claim 13 or 14, wherein the cement (200) comprises at least about 50 wt-%. of the additive .

17. The cement (200) according to any one of Claims 13 to 16, wherein the cement (200) comprises Ordinary Portland Cement (OPC) .

18. The cement (200) according to any of Claims 13 to 17, wherein the cement (200) further comprises less than 5 wt.-%, or less than 4 wt.-%, or less than 3 wt.-% plasticizers.

19. The cement (200) according to any of Claims 13 to 18, wherein the cement (200) is electrically conductive.

20. The cement (200) according to any one of Claims 13 to 19, wherein the cement (200) comprises less than about 1% carbon fiber .

21. A concrete composition comprising the cement (200) according to any one of Claims 13 to 20.

22. Concrete comprising the additive of any one of the Claims 1 to 12.

23. A concrete composition according to Claim 21 or 22, further comprising one or more steel bodies.

24. A cement (200) according to any one of Claims 13 to 20 or a concrete composition according to any one of Claims 21 to 23, wherein said cement (200) or concrete composition has an LCA of less than zero kg-CO2_eq.

25. A cement (200) according to any one of Claims 13 to 20 or 24, or a concrete composition according to any one of Claims21 to 24, wherein the cement (200) or concrete composition has a resistivity of about 100 ohm-cm or less.

26. A method for producing cement (200) or concrete, the method comprising: a. providing a mixture comprising one or more cement (210) powders and the additive according to any of claims 1 to 12; b. adding water to the mixture to obtain an aqueous mixture ; c. adding the aqueous mixture to a form; and d. curing the aqueous mixture.

27. The method of Claim 26, wherein the mixture obtained in step a. is mixed with one or more other concrete components.

28. The method of Claim 26 or 27, wherein the additive is mixed with one or more other concrete components prior to step a .

29. The method of Claim 27 or 28, wherein the one or more other concrete components comprise fine aggregate, coarse aggregate, plasticizer and / or one or more other concrete additives .

30. The method of any one of Claims 26 to 29, wherein the additive is electrically conductive, and in step d., curing is achieved by applying an electrical current to the aqueous mixture causing it to be heated.

31. The method of Claim 30, wherein the aqueous mixture is heated in step d. to a temperature of about about 50° to about 100°C.

32. The method of any one of Claims 26 to 31, further comprising adding a second additive according to any one of Claims 1 to 12.

33. The method of Claim 32, wherein the second additive comprises a different grade of biochar than the additive added in step a. of the method.

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