A modified biochar and concrete mixtures comprising modified biochar
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Y-MATTEC AS
- Filing Date
- 2024-06-14
- Publication Date
- 2026-04-29
Smart Images
Figure EP2024066580_26122024_PF_FP_ABST
Abstract
Description
[0001] A MODIFIED BIOCHAR AND CONCRETE MIXTURES COMPRISING MODIFIED BIOCHAR
[0002] Technical Field
[0003] The present invention relates to a method for modifying biochar and concrete mixtures comprising the modified biochar
[0004] Background
[0005] In recent years biochar has been used in the production of concrete by combining binders, aggregates and biochar and possibly other additives with the addition of aqueous solvents to produce a mixture, with cement and as binders sand, gravel, crushed stone, slag and / or recycled building material can be used as aggregates.
[0006] The use of biochar to reduce the use of cement has the advantage that the CO2 balance of concrete can be significantly improved. The linking of pyrolysis processes and the resulting climate-neutral energy in the form of electricity and heat for your own use, as well as the use of the resulting biochar to create carbon sinks, for example in concrete by replacing cement with the addition of specially produced biochar, and that everything in one place seems to be a perfect symbiosis. The concrete itself does not lose quality through this substitution of cement, but many properties are improved.
[0007] Concrete is a composite material of a binding medium, typically hydraulic cement and water, having particles or fragments of aggregate embedded therein and is the most utilized building material in world. Worldwide, 30 billion tons of concrete are used each year with the demand steadily growing. Global production and applications of concrete are estimated to consume more than 10 exa-joules of energy and release 2.2 gigatons of CO2 into the atmosphere, accounting for about 8% of the world's greenhouse gas emissions. The CO2 emissions are primarily due to the cement component in concrete. The process for manufacturing concrete is highly energy intensive and emits large amounts of greenhouse gases as a by-product. The energy required for this process is about 4 gigajoules per ton of cement produced. Carbon dioxide emissions occur from both primary and secondary sources, from the production process itself (calcination) and from the energy required to run the production process (combustion). The associated carbon dioxide emissions are about 900 kg CO2 per ton of cement produced. Thus, there remains a substantial need for new concrete formulations and methods of manufacture that can significantly decrease the impact of concrete production and use on the global environment, and use of biochar in concrete production may serve to reduce the carbon dioxide emissions.
[0008] The patent documents US 2022 / 298073 A1 and WO 2023 / 006136 A1 disclose concrete mixtures including biochar. Although, the known concrete mixtures comprising biochar have proven to provide concrete with acceptable properties, there is still a need for concrete mixtures with improved properties.
[0009] Disclosure of the Invention
[0010] The object of the invention is to provide a biochar for use in concrete mixture which biochar has improved properties.
[0011] A further object is to provide a concrete mixture including modified biochar, which concrete mixture has improved properties in respect of flow, strength and durability.
[0012] In a first aspect of the invention the invention relates to a method for modifying biochar in particular for use in concrete mixtures, said method comprising the steps of:
[0013] - providing a biochar,
[0014] - pulverizing the biochar to obtain a powdered biochar having a particle size in the range from about 1 pm to about 1200 pm, such as from 1 pm to about 1000 pm, 1 pm to about 800 pm,
[0015] - mixing the powdered biochar with a flow-improving agent in an amount from about 1%(w / w) to about 40%(w / w), such as from about 1 %(w / w) to about 20%(w / w), such as from about 1 %(w / w) to about 10%(w / w), and mixing the biochar and the flow-improving agent for at least one minute, such as 3 to 30 minutes, preferably 6 to 15 minutes
[0016] - obtaining a modified biochar by a (heat) reaction between the powdered biochar and the flow-improving agent after at least one hour, preferably from about 5 hours to about 30 hours, and
[0017] - recover the modified biochar from the mixing device.
[0018] In this context the term “concrete mixture” means cement based products such as concrete, mortars, oilwell cement mix, high strength concrete mix and wind turbine grout. The biochar may be any suitable biochar, e.g. biochar obtained from waste from farming. The flow-improving agent is an agent which improves the flow properties of the biochar and when the modified biochar is mixed into a concrete mixture, the flow of the concrete mixture is improved.
[0019] The reaction between the biochar and the flow-improving agent is considered to be a mix between an absorption process and a polymerisation process. The process may release heat from the biochar mixture.
[0020] The recovering step may be performed immediately after the mixing. The mixing of the biochar and flow-improving agent can be done in any suitable mixing device and the reaction step between the mixed biochar and flow-improving agent need not necessarily take place in the mixing device, thus, the mixture can be transferred to another container where the reaction can occur.
[0021] During the mixing step the flow-improving agent can simply be poured into the biochar, however, in an embodiment of the method according to the invention the flow-improving agent is injected into the powdered biochar while mixing.
[0022] The flow-improving agent which is used for modifying the biochar is an agent that improves the flow properties of the modified biochar and also the flow properties in the concrete mixture into which the modified biochar is mixed. Although, flow-improving agent can be selected from several groups of chemical compounds such as high-mo- lecular-weight synthetic copolymers, mixtures of salt and acid with organic solvents, and polyols in an embodiment the flow-improving agent is selected from polyols, such as glycerol, erythritol, threitol, adonitol, xylitol, arabitol, polyether polyols, such as glycol ether such as 1-(2-butoxy-1-methylethoxy)propan-2-ol, and tripropylene glycol n-butyl ether.
[0023] The invention also relates to a concrete mixture comprising at least modified biochar, inert filler and cement. The concrete mixture may comprise up to 60% modified biochar. All percentages are weight-% (%(w / w))
[0024] In an embodiment of the concrete mixture according to the invention the concrete mixture comprises the following ingredients: 20-60% inert filler
[0025] 20-50% cement
[0026] 2-25% modified biochar
[0027] 1-5% calcium sulfo aluminate
[0028] 0.05 - 0.5% aluminium powder blend
[0029] 0.05 - 0.8% plasticizer
[0030] 0.0 - 0.08% air control additive
[0031] 0.0 - 2.0% setting controlling additives and wherein the ingredients are mixed to form dry concrete mixture (100%) and water is added to the concrete mixture to form a flowable mixture where the water / cement ratio is below 0.33.
[0032] The cement in the concrete mixture is preferably Portland cement. The concrete mixture may also comprise 1 - 5% calcium sulfo aluminate. Calcium sulfo aluminate is a special type of cement. This special cement distinguishes itself from Portland cement by a highspeed bonding, fast strength development, and a shrinkage reduction. The initial set of the calcium sulfo aluminate cement begins after approximately twenty minutes and its final set is then arrived after ten more minutes. With the use of retarders, the processing time can be considerably extended. Even in low temperature environments calcium sulfo aluminate cement maintains its reactivity unlike other cement types When calcium sulfo aluminate cement is applied to concrete or mortars it vastly increases its strengths and its strength development. Compared to Portland cement, mortars and concrete with calcium sulfo aluminate will achieve the same strength within 24 hours where Portland takes 28 days.
[0033] 0.05 - 0.5% aluminium powder blend may also be included in the concrete mixture. The aluminium powder blend may serve to improve the compressive strength.
[0034] The concrete mixture may also comprise 0.05 - 0.8% plasticizers and superplastizisers.
[0035] Plasticizers and superplasticizers, also known as high range water reducers, are additives used for making high-strength concrete or to place self-compacting concrete. Plasticizers are chemical compounds enabling the production of concrete with approximately 15% less water content. Superplasticizers allow reduction in water content by 30% or more. Plasticizers and superplasticizers also retard the setting and hardening of concrete. 8. In an embodiment of the concrete mixture the plasticizer is a modified poly- carboxylatether.
[0036] The concrete mixture may also comprise 0.0 - 0.08% air control additives and 0.0 - 2.0% setting controlling additives.
[0037] Air control additives are chemical additives that provide controlled air entrainment into concrete mixtures, increasing its frost resistance and durability. Air entraining additives are used for manufacturing concrete and reinforced concrete products and structures. The air control additives are particularly useful for structures which are intended to operate in difficult climatic conditions. The air control additives are also used for constructing any kind of structures where the concrete frost resistance is required. In an embodiment of the concrete mixture the air control additive is based on fatty alcohol alkoxylates and polysiloxanes.
[0038] Setting controlling additives are additives used to control the setting, either to reduce or extend the setting time.
[0039] A larger number of suppliers can supply the above-mentioned materials and additives, and they are available under different trade names.
[0040] In yet an embodiment of the concrete mixture the concrete mixture comprises the following ingredients:
[0041] 30 - 90% cement
[0042] 2 - 60% modified biochar
[0043] 1 - 5% calcium sulfo aluminate
[0044] 0 - 40% light weight aggregate
[0045] 0 - 40% inert filler
[0046] 0.05 - 0.8% plasticizer / superplastiziser
[0047] 0.0 - 0.8% air control additive
[0048] 0.0 - 2.0% setting controlling additives
[0049] 0.0 - 4.0% rheology controlling additives and wherein the ingredients are mixed to form dry concrete mixture (100%) and water is added to the concrete mixture to form a flowable mixture where the water / cement ratio is below 0.60. A water / cement ratio up to 0,60 and preferably above 0.33 may serve to improve the flow of the concrete mixture.
[0050] The concrete mixture above may also include 0.0 - 4.0% rheology controlling additives. Rheology controlling additives improve rheological properties and displacement efficiency of concrete mixtures.
[0051] The inert filler may be gravel and stone and crushed concrete or light weight filler such as cenospheres, however in an embodiment of the concrete mixture the inert filler is quartz sand, preferably quartz sand and / or bauxite sand with a grain size in the range from about 0.08 mm to about 8 mm. Quartz sand and bauxite sand have excellent properties as inert fillers in concrete mixtures.
[0052] In an embodiment of the concrete mixture according to the invention, the mixture further comprises a viscosity-enhancing agent, preferably in an amount from 0.01 to 0.1%, and preferably a viscosity-enhancing agent based on high molecular weight water-soluble polymers.
[0053] The concrete mixture may have a strength of at least 20 MPa, such as at least 40MPa or at least 80 MPa. In an embodiment the compressive strength of the concrete mixture (according to DS EN 12390-3:2019. Testing hardened concrete) is at least 100MPa.
[0054] By using the concrete mixture with modified biochar, where the biochar is modified in a standalone operation with reaction with the flow-improving agent before adding to the concrete mixing, much better results can be achieved in comparison to concrete mixtures with non-modified biochar, even if the flow-improving agent is added to the concrete mixture and mixed with the components including the biochar during preparation and mixing of the concrete mixture.
[0055] By using the modified biochar according to the invention a better flow in concrete mixture can be achieved during casting, and concrete structures with strengths above 100MPa, above 120MPa or even above 140MPa can be achieved.
[0056] Brief description of the figures The invention is explained in detail below with reference to the an example and figures in which:
[0057] Fig. 1 shows the biochar before treatment;
[0058] Fig. 2 shows biochar after addition of flow-improving agent;
[0059] Fig. 3 shows sample of non-modified biochar;
[0060] Fig. 4 shows samples of modified biochar.
[0061] This example describes how to modify a biochar material according to the invention using a flow-improving agent (FIA) [1-(2- butoxy-1-methylethoxy)propan-2-ol]. The modification results in making the biochar (BC) suitable for its use in a high strength (>100 MPa) self-compacting mortar recipe, presumably as a pozzolanic material that could replace a part of the cement.
[0062] All the tests took place at Y-MatTec’s laboratory facilities.
[0063] References:
[0064] ASTM C1437 - 20. Standard Test Method for Flow of Hydraulic Cement Mortar.
[0065] DS EN 12390-3:2019. Testing hardened concrete - Part 3: Compressive strength of test specimens.
[0066] Test
[0067] Modification of the biochar with the flow-i
[0068] The pyrolysis ashes received (figure 1) were made from a chicken farm's waste. In appearance, the sample was black and homogeneous, with small agglomerations of material, which were easy to disintegrate only by applying very little pressure with a spoon. Also, it had a mild smell of “rotten eggs”, that could be characteristic of the present of sulfide and / or sulfur compounds.
[0069] Three (3) portions of 100gr each of biochar were weighed. Each portion was mixed with different percentages of flow-improving agent - see figure 2:
[0070] Portion 1 : 7.1% by weight of FIA.
[0071] Portion 2: 25% by weight of FIA.
[0072] Portion 3: 40% by weight of FIA.
[0073] Mixing procedure:
[0074] Hand mixed for one minute.
[0075] Mix in the Hobart mixer for 2 minutes.
[0076] After mixing, the samples were placed inside the chemical fume hood for the next 24 hours and the temperature was monitored.
[0077] Mortar mixes with non-modified biochar.
[0078] The following mixes were made. All mixes are based on Y-MatTec’s LIHPC mortar (130 MPa).
[0079] W / C = 0.2.
[0080] Mix 1 : Replace 10% cement with non-modified BC + 7.1 % FIA.
[0081] Mix 2: Replace 10% of cement with non-modified BC + 25% FIA.
[0082] Mix 3: Replace 10% of cement with non-modified BC + 40% FIA.
[0083] Mixing procedure:
[0084] Mix all the dry components for 1 minute in the Hobart mixer at low speed.
[0085] Add the FIA and mix for 2 minutes.
[0086] Add the water.
[0087] Mix for 6 minutes.
[0088] After mixing, the temperature of the grout was recorded, and the ASTM flow was measured.
[0089] Mortar mixes with the modified biochar.
[0090] The following mixes were made. All mixes are based on Y-MatTec’s LIHPC mortar (130 MPa). W / C = 0.2.
[0091] Mix 4: Replace 10% of cement with modified BC + 7.1 % FIA. Mix 5: Replace 10% of cement with modified BC + 25% FIA.
[0092] Mix 6: Replace 10% of cement with modified BC + 40% FIA.
[0093] Mixing procedure:
[0094] Mix all the dry components for 1 minute in the Hobart mixer at low speed.
[0095] Add the water.
[0096] Mix for 6 minutes.
[0097] After mixing, the temperature of the grout was recorded, and the ASTM flow was measured.
[0098] Results
[0099] Treatment of the biochar with the flow-improving agent.
[0100] Temperature of reaction: the temperature remained constant at 23.1°C during all the 24 hours.
[0101] Physical changes: for the three samples, the particles look more hydrated than the BC without modification.
[0102] Odor: after 24 hours, the smell of rotten eggs in the powder was not perceptible.
[0103] Reaction with water: when mixing with water, the material without treatment looks very different than the treated one. A lawyer of an oily compound was released into the water, which is not evident in BC with FIA.
[0104] The BC reacts with water releasing a gas, which has rotten eggs smell. This reaction is more noticeable on the modified material, where the air bubbles are very evident (videos can be provided). Mortar mixes with the non-modified and modified biochar.
[0105] The results are summarized in Table 1.
[0106] *The biochar was not pretreated, the FIA was added directly to the mix
[0107] Table 1. Flow results The results comparison between modified BC with FIA and non-treated BC where the same amount of FIA added directly to the mix is summarized in Table 2.
[0108] Table 2. Compared flow results between mixes with pretreated BC and untreated BC with FIA added to the mix.
[0109] The modification of the BC improved the mixability of the mortar, compared with the sample with the non-modified BC, as well as the viscosity and the flow. The use of the modified biochar in concrete mixes also improves the possibility to achieve higher strengths (after 28 days) of the concrete. In terms of flow, the influence of adding more FIA than 7.1 % was not very evident. However, the modified biochar with more FIA were easier to mix and a little less viscous.
Claims
Claims1. A method for modifying biochar in particular for use in concrete mixtures comprising the steps of:- providing a biochar- pulverizing the biochar to obtain a powdered biochar having a particle size in the range from about 1 pm to about 1000 pm- mixing the powdered biochar with a flow-improving agent in an amount from about 1%(w / w) to about 40%(w / w) and mixing the biochar and the flow-improving agent for at least one minute, preferably 6 to 15 minutes- obtaining a modified biochar by a reaction between the powdered biochar and the flowimproving agent after at least one hour, preferably from about 5 hours to about 30 hours, and- recover the modified biochar from the mixing device.
2. A method according to claim 1 wherein the flow-improving agent is injected into the powdered biochar while mixing.
3. A method according to claim 1 , wherein the flow-improving agent is selected from polyols, such as glycol ether such as 1-(2-butoxy-1-methylethoxy)propan-2-ol, and tripropylene glycol n-butyl ether.
4. A concrete mixture comprising at least modified biochar produced by a method according to claims 1-3, inert filler and cement.
5. A concrete mixture according to claim 4, wherein the concrete mixture comprises the following ingredients :20-60% inert filler20-50% cement2-25% modified biochar1-5% calcium sulfo aluminate0.05 - 0.5% aluminium powder blend0.05 - 0.8% plasticizer0.0 - 0.08% air control additive0.0 - 2.0% setting controlling additivesand wherein the ingredients are mixed to form dry concrete mixture (100%) and water is added to the concrete mixture to form a flowable mixture where the water / cement ratio is below 0.33.
6. A concrete mixture according to claim 4, wherein the concrete mixture comprises the following ingredients:30 - 90% cement2 - 60% modified biochar1 - 5% calcium sulfo aluminate0 - 40% light weight aggregate0 - 40% inert filler0.05 - 0.8% plasticizer / superplastiziser0.0 - 0.8% air control additive0.0 - 2.0% setting controlling additives0.0 - 4.0% rheology controlling additives and wherein the ingredients are mixed to form dry concrete mixture (100%) and water is added to the concrete mixture to form a flowable mixture where the water / cement ratio is below 0.60.
7. A concrete mixture according to any one of the claims 4 to 6, wherein the inert filler is quartz sand, preferably quartz sand and / or bauxite sand with a grain size in the range from about 0.08 mm to about 8 mm.
8. A concrete mixture according to any one of the claims 4 to 7, wherein the plasticizer is a modified polycarboxylatether9. A concrete mixture according to any one of the claim 4 to 8, wherein the air control additive is based on fatty alcohol alkoxylates and polysiloxanes10. A concrete mixture according to any one of the claims 4 to 9, wherein the mixture further comprises a viscosity-enhancing agent, preferably in an amount from 0.01 to 0.1%, and preferably based on high molecular weight water-soluble polymers.