285 results about "Pozzolan" patented technology

The purpose of this invention is to provide a method for preparing cemented backfill materials based on response surface methodology using composite activating coal gasification slag. This method belongs to the field of mining engineering technology. Based on sorting and removing impurities from the coal gasification slag and drying it, the invention obtains ultrafine powder of the coal gasification slag for preparing the backfill material through ball milling. Then, coal gangue is crushed and screened using a crusher to obtain coarse, medium, and fine aggregates for the backfill material. Finally, cement, ultrafine coal gasification slag powder, coal gangue aggregate, activator, and water are mixed evenly to prepare the cemented backfill material. This invention not only solves the problem of low activity of coal gasification slag volcanic ash but also effectively controls the shortage of cemented backfill materials and high backfilling costs during cemented backfill mining, ensuring sustainable development. Furthermore, it effectively utilizes the widely accumulated coal gasification slag, reducing pollution and large-scale land occupation of the surrounding environment.

The invention belongs to the technical field of mine goaf filling materials, and particularly discloses flow-state solidified loess for coal mine filling and a preparation method and application of the flow-state solidified loess. According to the method, rich loess resources in the loess plateau area are used for preparing the flow-state solidified loess for coal mine filling, the coal mine recovery rate can be increased, the filling material cost is reduced, the problem that stones in the loess plateau area are insufficient is solved, the toughness and dry shrinkage resistance of the solidified flow-state solidified loess can be improved, and the problem that the loess is soft and swelled when meeting water is effectively solved. The curing agent for the fluid-state cured loess is developed according to the characteristics of loess of loess plateau and the characteristics of early strength, fluidity, pumpability, crack resistance and the like required by filling of the fluid-state cured loess, the alkali excitation mechanism, the pozzolanic effect, the secondary hydration reaction and other mechanisms are utilized, and proper functional components such as early strength, water retention and crack resistance are compounded, so that the curing agent for the fluid-state cured loess is prepared. The curing agent can effectively solve the common problems of air shrinkage, easy cracking, low strength and the like when a commercially available curing agent is used for preparing flow-state cured loess.

Pumpable slurry compositions including at least one aluminosilicate additive and optional pozzolanic cement additives and methods including the pumpable slurry compositions improve development of compressive strengths in the pumpable cement slurry compositions. The methods utilize one or more pumpable cement slurry compositions including at least one cement component, water, at least one first aluminosilicate additive, at least one optional second aluminosilicate additive, and one or more optional pozzolanic additives, where the at least one first aluminosilicate additive has an amorphous phase of greater than about 50% and a weight ratio of silica oxide to aluminum oxide of about 1.0 to about 2.5, and the at least one optional second aluminosilicate additive has a weight ratio of silica oxide to aluminum oxide of about 1.7 to about 3.3.

The invention relates to the technical field of grouting materials, in particular to a dynamic water environment anti-dispersion micro-expansion grouting material and a preparation method thereof. A component A of the grouting material mainly comprises the following raw materials in parts by weight: 120-160 parts of a gel material with volcanic ash characteristics, 3-5 parts of a retarder, 10-15 parts of magnesium oxide, 0.5-2 parts of citric acid, 5-8 parts of aluminum sulfate, 1-2 parts of sodium fluoride, 0.5-1 part of gelatin and 70-100 parts of water; the component B mainly comprises the following raw materials in parts by weight: 4-8 parts of polyacrylamide, 5-10 parts of polyacrylic acid derivative salt, 1-2 parts of alcohol polysaccharide, 40-100 parts of water glass and 30-50 parts of water; magnesium oxide, aluminum sulfate, gelatin and sodium fluoride in the component A are prepared into core-shell anti-dispersion particles in advance; the problems that a traditional cement grouting material is poor in anti-scouring capacity and anti-dispersing capacity, low in retention rate, poor in stone durability and the like can be solved.

The invention discloses a high-impermeability concrete material and a preparation method thereof, and belongs to the technical field of concrete materials, and the high-impermeability concrete material specifically comprises the following components in parts by weight: 80-100 parts of stones, 40-60 parts of quartz sand, 25-35 parts of cement, 8-12 parts of an impermeability reinforcing material, 3-5 parts of sodium carboxymethyl cellulose, 1.5-1.8 parts of an additive and 25-30 parts of water. The Portland pozzolana cement concrete is reinforced through mutual cooperation of sodium carboxymethyl cellulose and an anti-permeability reinforcing material, so that the compressive strength and the water permeability resistance of the cement concrete are effectively improved, the corrosion resistance of chloride ions and sulfate is improved, and the service life of the cement concrete in a high-ion environment is prolonged.

Hydraulic binder composition comprising: a mixture of (i) between 20 and 95 dry wt % of at least one steel making slag, (ii) between 4 and 79 dry wt % of at least a slag different from (i) and / or at least one pozzolanic material and / or at least one inert filler, and (iii) between 1 and 25 dry wt % of at least one co-binder; between 0.01 and 10 dry wt %, relative to the mixture total dry weight, of at least one steel making slag accelerator, between 0.1 and 5 dry wt %, relative to the mixture total dry weight, of at least one alkali activator for reacting (i), (ii), and / or (iii) with water, the alkali activator different from the slag accelerator and chosen among alkali mineral salts and mixtures thereof; and between 0.1 and 2 dry wt %, relative to the mixture total dry weight, of at least one fluidification agent.

The inorganic quick-setting filling material comprises a material A and a material B. The material A is prepared from the following components in parts by weight: 25-35 parts of sulphoaluminate cement, 30-40 parts of blast furnace slag, 10-20 parts of waste gypsum, 1-3 parts of recycled alumina fiber, 5-10 parts of volcanic ash and 0.8-1.2 parts of (3, 6-diamino acridine-9-yl) boric acid. The material B is prepared from the following raw materials in parts by weight: 4 to 6 parts of functional water-soluble resin, 1 to 2 parts of sodium 3-(N-morpholinyl)-2-hydroxypropanesulfonate, 0.5 to 0.8 part of sucralose, 0.1 to 1 part of sodium lignin sulfonate, 0.8 to 1.2 parts of 1, 3, 5-triglycidyl-S-triazinetrione and 0.1 to 0.5 part of sodium N-(trimethoxysilylpropyl) ethylenediamine triacetate. The material is good in rapid hardening effect, high in compressive strength, good in flame-retardant and antistatic performance and long in service life.

The invention belongs to the technical field of negative carbon building materials, and particularly relates to a multi-element solid waste negative carbon cement-based material and a preparation method thereof. The material is prepared from the following components in parts by weight: 10 to 320 parts of carbonized carbide slag, 0 to 240 parts of uncarbonized carbide slag, 25 to 640 parts of calcined coal gangue, 25 to 800 parts of Portland cement, 6 to 320 parts of silica fume and other pozzolanic mineral admixtures and 30 to 800 parts of mixing water. The preparation method comprises the following steps: carbonizing the carbide slag until the content of calcium carbonate is more than or equal to 90%, and calcining and activating the coal gangue at 700-800 DEG C; all the powder raw materials are subjected to dry mixing, water is added for segmented stirring, and standard curing is performed after pouring forming. The carbonized carbide slag is used for replacing limestone to achieve carbon sequestration, the calcined coal gangue is used for replacing calcined clay, natural resources are prevented from being exploited, the cement clinker replacement rate of 70% is achieved through the synergistic effect of multi-element solid waste in a low clinker system, the material has excellent mechanical and durability, and carbon emission and resource consumption are remarkably reduced.

The invention discloses a fly ash-based admixture and a preparation method thereof, and belongs to the technical field of building materials. The fly ash is used as a main body and cooperates with the slag, the steel slag and the volcanic rock powder, so that the utilization rate of industrial solid wastes is remarkably increased, the cement consumption is reduced, the hydration heat of the concrete is reduced, temperature cracks of mass concrete can be effectively inhibited, and meanwhile, the introduction of the volcanic rock powder further supplements active silicon-aluminum components, enhances the volcanic ash effect and improves the later strength; by introducing gypsum, the setting time can be adjusted, a sulfate excitation environment is provided, an early hydration reaction of a fly ash system is promoted, the problem that a traditional admixture is low in early strength is solved, concrete pores are filled through the micro-aggregate effect of the fly ash-based admixture, the structure is denser, and anti-permeability and mechanical properties are improved.

A method of preparation of a foamed concrete, comprising the steps of; providing a cementitious slurry, comprising in wt% relative to the wt of the slurry, 60-70% of a cementitious material, 0.5-5% in

A cement composition includes a curable component in an amount of 10 to 25 wt. %; a fine aggregate (FA) in an amount of 20 to 40 wt. %; a coarse aggregate (CA) in an amount of 40 to 50 wt. %; and an alkaline component in an amount of 5 to 15 wt. %, each wt. % based on the total weight of the cement composition. The curable component includes a cementitious material having an average particle size (D50) of 10 to 17 micrometers (μm), a limestone powder (LSP) material having a D50 of 13 to 19 μm, a red mud (RM) material having a D50 of 30 to 36 μm, a silicomanganese fume (SMF) material having a D50 of 28 to 34 μm, and a natural pozzolan (NP) material having a D50 of 13 to 19 μm.

The invention discloses high-performance fiber-blended seawater and sea sand concrete and a preparation method thereof. The high-performance fiber-blended seawater and sea sand concrete is prepared from the following raw materials: cement, fly ash, silica fume, coarse aggregate, sea sand, seawater, a water reducing agent, polyvinyl alcohol fibers and basalt fibers. Polyvinyl alcohol fibers, basalt fibers and a high-quality mineral admixture are mixed and doped in a seawater and sea sand concrete matrix, a three-dimensional framework is formed in the interior macroscopically, aggregate is effectively wrapped, internal defects of the concrete are reduced, the mechanical property is improved, the bridging effect of the mixed fibers is exerted microscopically, and the anti-cracking performance of the concrete is improved. And silica fume, fly ash and Ca (OH) 2 are subjected to a pozzolanic effect to generate low-alkalinity calcium silicate hydrate gel with high strength and excellent stability, so that the ion curing capacity of the seawater and sea sand concrete is improved, and the compactness and durability of a concrete matrix are improved. The fibers and the mineral admixture have a synergistic effect, so that the internal microstructure and durability of the concrete are enhanced, and the concrete can better adapt to low-temperature, freeze-thaw, corrosion and other complex environments.

The invention discloses a dredged sludge full industrial waste residue curing material proportion optimization method and system, and the method comprises the steps: carrying out a proportion test on dredged sludge by adopting cement, mineral powder and desulfurized gypsum according to a volcanic ash, alkali and sulfate synergistic curing mechanism, determining the optimal mixing ratio of each material, and giving chemical component mass ratios of SO3 / Al2O3, CaO / Al2O3 and (CaO + MgO) / SiO2; the method comprises the following steps: investigating industrial waste residues in a dredging engineering preset range, dividing the industrial waste residues into three types: an active base material, an alkali-activated material and a sulfate-activated material, and measuring chemical components of the industrial waste residues; according to the chemical components and the target mass ratio of the chemical components determined by the ratio test, three target functions for optimizing the ratio of the whole industrial waste residue curing material are established; and searching an optimal solution meeting the three objective functions by using an optimization algorithm. The method can solve the problem of proportion change caused by difference of chemical components of industrial waste residues in different regions, the proportion optimization efficiency is greatly improved, and the popularization value is extremely high.

Disclosed herein is a bio-concrete composition comprising a bio-cement; where the bio-cement comprises a bio-mineralized algae, a silica source, pozzolan, biochar and / or bioash; and an aggregate; where the aggregate comprises a secondary binder, sand and / or rock. Disclosed herein too is a method of manufacturing a transportable dry composition comprising blending together a microorganism package; a nutrient; and a first liquid media; activating the microorganism package; subjecting the microorganism package to desiccation to form a bio-mineralized algae; mixing the bio-mineralized algae with a silica source, pozzolan, biochar and / or bioash to form a bio-cement; and mixing the bio-cement with an aggregate to form a bio-concrete.

In general, in one aspect, embodiments relate to a method of producing a sustainable pipeline of pozzolanic materials that includes gathering unstructured and / or structured data publicly available on a network, identifying analytical data of a pozzolanic material using one or more machine learning models, where the analytical data is present within at least the structured data, extracting the analytical data from the structured data, predicting, using one or more predictive models, one or more performance characteristics of the pozzolanic material based at least in part on the analytical data, to form one or more predicted performance characteristics, comparing the predicted one or more performance characteristics to one or more minimum acceptable performance characteristics, storing the extracted analytical data and the one or more predicted performance characteristics in a database if the one or more performance characteristics meets or exceeds the minimum acceptable performance characteristic, and preparing a cement composition that includes the pozzolanic material if the predicted one or more performance characteristics meets or exceeds the one or more minimum acceptable performance characteristics.

The invention relates to the technical field of building engineering materials, in particular to an inorganic grouting material with adjustable curing time and a use method thereof. The inorganic grouting material provided by the invention comprises a main material and an adjusting material, the main material comprises the following components in parts by mass: 50-70 parts of sulphoaluminate cement clinker, 10-20 parts of quartz powder, 10-20 parts of gypsum, 3-5 parts of nano volcanic ash, 0.5-1 part of a water reducing agent and 0.1-1.5 parts of a retarder; the adjusting material comprises a composite coagulant and hydroxypropyl methyl cellulose. Through innovation of a material formula and innovation of a construction process, the problem that the grouting effect is poor due to the fact that a traditional grouting material cannot change the solidification time according to variable underground grouting scenes and requirements is solved; accurate grouting can be achieved under the conditions of different grouting depths, different crushing degrees, different diffusion radiuses, different mixing water temperatures, different coal and rock mass temperatures, different water inflow and the like.

The present invention provides a low shrinkage hybrid steel fiber recycled aggregate ultra-high performance concrete and a preparation method thereof, and belongs to the technical field of concrete. The low shrinkage hybrid steel fiber recycled aggregate ultra-high performance concrete of the present invention has high strength, good toughness, low shrinkage, and at the same time has the advantages of low cost and green environmental protection. By replacing part of the cement as a cementitious material with a large amount of fly ash, not only can its volcanic ash activity and particle filling effect be fully exerted, but also carbon dioxide emissions can be reduced. The present invention uses aeolian sand and recycled fine aggregate to replace traditional quartz sand through grading optimization, and then reduces the shrinkage of ultra-high performance concrete by adding recycled coarse aggregate and utilizing the volume stabilization effect of recycled aggregate. Finally, long steel fibers are added to cooperate with fine steel fibers to improve the flexural toughness of ultra-high performance concrete.

Disclosed herein is a biomineral supplemental blend for the replacement of hydraulic cement to create sustainable controlled low strength material (CLSM) with composition comprising a biomineralized algae, a silica source, pozzolan, biochar and / or bio-fly ash; and an aggregate; where the aggregate comprises a secondary binder, sand and / or rock, hydraulic cement, and filler material(s). Also disclosed herein is a method of manufacturing a transportable dry biomineral supplemental blend CLSM dry paste composition comprising blending together a microorganism package, a biomineralized algae, biochar and / or bio-fly ash, and pozzolan; mixing the biomineral supplemental blend, with hydraulic cement, cementitious materials, and liquid media to form a sustainable CLSM paste; and mixing the sustainable CLSM paste with an aggregate to form a sustainable CLSM mix design.

The invention provides low-shrinkage mixed steel fiber recycled aggregate ultra-high performance concrete and a preparation method thereof, and belongs to the technical field of concrete. The low-shrinkage mixed steel fiber recycled aggregate ultra-high performance concrete has the advantages of being high in strength, good in toughness, low in shrinkage rate, low in cost and environmentally friendly at the same time, large-dosage fly ash is used for replacing part of cement to serve as a cementing material, the volcanic ash activity effect and the particle filling effect of the high-shrinkage mixed steel fiber recycled aggregate ultra-high performance concrete can be fully exerted, and the service life of the low-shrinkage mixed steel fiber recycled aggregate ultra-high performance concrete is prolonged. And the emission of carbon dioxide can be reduced. The aeolian sand and the recycled fine aggregate are used for replacing traditional quartz sand through grading optimization, then the shrinkage of the ultra-high performance concrete is reduced by doping the recycled coarse aggregate and utilizing the volume stabilization effect of the recycled coarse aggregate, and finally the bending toughness of the ultra-high performance concrete is improved by adding the long steel fibers to cooperate with the fine steel fibers.

The invention provides a preparation method of single-component alkali slag-regenerated micropowder cement. The method comprises the following steps: mixing regenerated micro powder, slag, nickel slag and a solid alkali activator, and carrying out ball milling to prepare the single-component alkali slag-regenerated micro powder cement. Potential volcanic ash activity in the regenerated micro powder is activated through two activation means of mechanochemistry and alkali excitation, the particle morphology is improved by adjusting the proportion of RBP and RCP in the regenerated micro powder, the alkalinity of a system is increased through nickel slag, the alkali excitation reaction process is promoted, and macroscopic performance is improved. The invention aims to realize resource utilization of the building solid waste regenerated micro powder, the regenerated micro powder is introduced, the mechanical property of the cement is improved, and greenization of a cementing material, an admixture and a production process is realized.

The invention belongs to the technical field of coal-based solid waste resource utilization, and particularly relates to a high-performance kerb with high salt freezing resistance and high flexural tensile strength, which comprises a cementing material, a fine aggregate, a coarse aggregate and water, the cementing material is cement and CFB fly ash, the fine aggregate is CFB slag and machine-made sand, the coarse aggregate is 3-5mm granite and 5-8mm granite, and the water is water. Comprising the following components in parts by weight: 113 to 245 parts of CFB fly ash, 225 to 809 parts of CFB slag, 506 to 613 parts of cement, 383 to 858 parts of machine-made sand, 338 to 417 parts of granite of 3 to 5mm, 338 to 417 parts of granite of 5 to 8mm and 173 to 240 parts of water, and 2450 parts of the CFB fly ash, the CFB slag, the cement and the granite are taken as the total base number. According to the curb, on one hand, resource utilization of solid waste can be achieved, and on the other hand, the production cost of the curb can be reduced; by utilizing the characteristics of self-hardening, volcanic ash activity and micro-expansibility of CFB ash, the CFB fly ash is used for replacing an expanding agent or expansive cement to compensate the shrinkage of the curb; secondly, the fineness modulus of the CFB slag is in a medium sand range, part of machine-made sand is replaced, closed holes are formed in the kerb, the salt freezing resistance of the kerb is improved, and cellulose and an air entraining agent do not need to be added.

The invention comprises a method of making lime, dolomitic lime, hydraulic cement such as portland cement clinker and co-products such as pozzolan, acids, alumina, silica and the like while producing reduced amounts of carbon dioxide. The method comprises combining hyaloclastite with a first acid to form a first salt, combining the first salt with a second acid to form a second salt and heating the second salt to form an oxide.

A coastal karst cement-based expanding grouting material and a preparation method therefor. The material comprises components A and B; the component A comprises a cementing material with volcanic ash characteristics, water and an expanding agent of 0.01-6.0%; and the component B comprises the following in weight percentages: 0.2-1.3% of a water-soluble vegetable gum, 0.5-2.0% of polyacrylamide, 0.01-2.0% of a polyacrylic acid derivative salt, 0.02-1.5% of a complexing agent, 0.05-1.5% of polyhydroxy polysaccharides, 2-70% of water glass and 42.3-90.3% of water. The coastal karst cement-based expanding grouting material has good stability in flowing water, and can fill and reinforce unfavorable geological structures in coastal karst areas, specifically filling fissures and karst caves, plugging water passing channels and the like. Besides, the expansion of the cement-based expanding material is adjustable and can be adjusted and controlled according to the actual filling working condition of the karst caves.

The present disclosure relates to shaped cementitious compositions that comprise a substrate for aquatic flora and / or fauna attachment; methods for providing a substrate for aquatic flora and / or fauna attachment comprising depositing a shaped cementitious composition into a body of water; and methods for making a shaped cementitious composition. The shaped cementitious composition is formed from a pourable cementitious mixture comprising: (a) a pozzolan comprising a natural pozzolan and / or a manmade pozzolan; (b) MgO and / or Mg(OH)2; (c) an aqueous solution comprising one or more accelerants; and (d) at least one aggregate. In some cases, the MgO and / or Mg(OH)2 of (b) is included in the aqueous solution of (c). And, in various cases, the manmade pozzolan comprises a slag.

The invention relates to the field of building materials, and particularly discloses green low-carbon concrete and a preparation method thereof, and the green low-carbon concrete comprises the following raw materials: cement, modified recycled aggregate, a composite admixture, a water reducing agent, a strength-promoting shrinkage-reducing agent, reinforced fibers and water; wherein the composite admixture is a mixture of fly ash and steel slag powder and / or volcanic ash; the modified recycled aggregate is prepared by sequentially crushing, cleaning, modifying and grading building waste; the preparation method comprises the following steps: dry-mixing the cement and the composite admixture, and then mixing with the modified recycled aggregate and the reinforced fiber to prepare a dry mixture; mixing the strength-promoting shrinkage-reducing agent, the water reducing agent and water to obtain a mixture, mixing the mixture with the dry mixture, and stirring to obtain the green low-carbon concrete. The method has the characteristics that the cement consumption is reduced, the industrial solid waste utilization rate is increased, and meanwhile, the concrete strength and the impermeability are improved.

The invention discloses a low-carbon composite cementitious material, a mortar preparation method and application, and the low-carbon composite cementitious material comprises the following raw materials by weight: 50%-85% of cement, 15%-50% of Yellow River mud sand micro powder, 0%-0.75% of a sodium hydroxide activator, and 0%-7.5% of a calcium hydroxide activator. The method has the beneficial effects that the specific surface area of the Yellow River mud sand is influenced through mechanical grinding, more nucleation sites are generated on the surface of the Yellow River mud sand, the subsequent hydration reaction of the Yellow River mud sand and cement is promoted, and the Yellow River mud sand is easy to form micro-group aggregation through grinding, so that internal pores are filled, the porosity is reduced, and the strength is improved; and through the composite excitation effect of the two alkali activators, the generation of C-S-H and C-A-S-H gels is promoted, the pore size distribution is refined, the microstructure is improved, and the potential volcanic ash or activity of sediments is excited to the maximum extent.

Disclosed herein is a biomineral supplemental blend for the replacement of hydraulic cement to create sustainable cement and concrete with composition comprising a biomincralizcd algae, a silica source, pozzolan, biochar and / or bio- fly ash; and an aggregate; where the aggregate comprises a primary binder, a secondary binder, sand and / or rock, hydraulic cement, filler material(s), and admixtures. Also disclosed herein is a method of manufacturing a transportable dry biomineral supplemental blend composition comprising blending together a microorganism package, a biomineralized algae, biochar and / or bio-fly ash, and pozzolan; mixing the biomincral supplemental blend with hydraulic cement, cementitious materials, and liquid media to form a sustainable cement; and mixing the sustainable cement with an aggregate to form a sustainable concrete.

The present invention discloses a low-viscosity and high-strength cement-based grouting material and a preparation method thereof. The grouting material comprises the following components: 300-600 parts of a cementitious material having volcanic ash properties, 0.2-0.6 parts of a micro-nano coagulant, a water reducer of 0.25-2% of the mass of the cementitious material, and a water-cement ratio of 0.4-0.8. The cementitious material having volcanic ash properties comprises silicate cement and modified microbeads. The preparation method comprises the following steps: uniformly mixing the cementitious material having volcanic ash properties and the micro-nano coagulant. Then, a mixed solution formed by the water reducer and water is added, and the mixture is uniformly stirred to obtain the cement-based grouting material. The present invention reduces the water-cement ratio of cement slurry and ensures the strength of cement stone, while reducing the viscosity of cement slurry and improving injectability.

The invention relates to the technical field of building materials, and discloses a preparation method of a functional additive of antibacterial and mildew-proof dry-mixed putty mortar, which comprises the following steps: dispersing an inorganic porous carrier in water, and adding a plant polyphenol solution for adsorption loading; then adding soluble silicate, adjusting the pH value of the system to be acidic or weakly acidic, and carrying out in-situ gelation reaction to form a silica gel blocking layer on the surface of the carrier; and adding a metal salt solution to carry out heating coordination reaction, and carrying out solid-liquid separation, washing, drying and crushing to obtain a finished product. Intelligent slow release and oxygen isolation protection of active components are achieved by constructing a pH response type silica gel layer and a metal-polyphenol coordination network, the additive effectively solves the problems of serious delayed coagulation and oxidation discoloration caused by plant polyphenol in an alkaline putty system, an active silicon source generated by dissolution of the silica gel layer can be subjected to a pozzolanic reaction, and the pH response type silica gel layer and the metal-polyphenol coordination network can be used for preparing the alkaline putty. The bonding strength of the putty layer is obviously improved.

The present disclosure relates to cement compositions including Portland cement and volcanic ash. An exemplary cement composition includes about 10 wt % to about 85 wt % of Portland cement, and about 10% by weight of cement (BWOC) to about 70% BWOC of volcanic ash.