Recycled Cement Production Methods and Applications

Cementitious material and preparation method that replaces traditional cement in construction applications while reducing carbon emissions. The material comprises waste concrete powder that undergoes mechanical grinding and heat activation to produce a cement-like material with improved hydration properties. The process involves grinding concrete into smaller particles, activating them through heat treatment, and then combining the activated concrete with other cement components. This material exhibits enhanced hydration characteristics and mechanical strength compared to traditional cement, making it suitable for applications requiring improved durability and performance.

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Method for producing reclaimed cementitious fines from demolished cement-containing materials to replace virgin cement in concrete and mortar production. The method involves crushing and processing reclaimed cement-containing waste materials, including recycled concrete aggregate, demolished concrete aggregates, and demolished brick or block walls containing cement-based mortar, into finely-sized cementitious fines. These reclaimed fines can be used as a direct substitute for virgin cement in cement paste, mortar, and concrete mixes, eliminating the need for virgin cement production and associated greenhouse gas emissions.

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A method for preparing a high-performance cement additive that enables enhanced cement hydration and improved compressive strength through controlled mineralization. The additive is prepared by first crushing and sieving waste concrete into fine particles, followed by repeated crushing to achieve a particle size less than 2 mm. The crushed particles are then subjected to controlled mineralization in a reactor at 1MPa pressure with CO2 at 50% RH for 24 hours. The resulting mineralized cement additive exhibits significantly improved hydration properties and compressive strength compared to conventional cement, making it suitable for cement-based construction applications.

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A novel, carbon-negative building material comprising a 95% recycled iron-based compound with compressed carbon dioxide curing, offers enhanced durability and strength compared to conventional Portland cement. The material, known as Ferrock, incorporates compressed carbon dioxide to expedite curing and eliminates the need for added heat, while its iron-based composition reduces embodied carbon emissions. The compound's unique composition and curing process provide improved mechanical properties and reduced porosity compared to conventional Portland cement.

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A waste brick material that combines the benefits of recycled construction waste with the performance of traditional clay bricks. The material comprises a mixture of waste aggregates with specific size distributions, specifically between 40-80% fine aggregate (0.30-1.20 mm) and 20-60% coarse aggregate (20-60 mm), which enables enhanced durability and thermal resistance while maintaining the structural integrity of the brick.

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A prefabricated concrete block made from a mixture of recycled aggregates and cement with reduced carbon footprint. The block combines a recycled aggregate from construction waste with a lower-carbon cement type, achieving a 17.6% reduction in CO2 emissions compared to conventional cement. The production process incorporates solar energy for electricity generation, further enhancing the eco-friendly profile of the block. The innovative composition replaces traditional volcanic stone with crushed recycled aggregates, while the cement is replaced with a lower-carbon cement type.

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A cement substitute made from waste clay and/or pottery, and a method of manufacturing the same, that reduces carbon dioxide emissions while maintaining cement's strength. The substitute is produced by mixing waste clay and purified sludge, then firing at lower temperatures (500-900°C) to create a low-temperature fired clay with enhanced hydraulic properties. The resulting low-temperature fired clay can be used as a cement substitute in cement production, achieving significant carbon dioxide reduction without compromising setting time or compressive strength.

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A cementitious material that replaces traditional Portland cement in concrete production while significantly reducing greenhouse gas emissions. The material comprises a brine slurry of water, magnesium hydroxide, and selected salts, combined with slag. When mixed with aggregate, the brine slurry forms a concrete that absorbs and retains CO2 during curing, making it a viable alternative to traditional cement. The material achieves this through its unique brine composition, which not only absorbs CO2 but also provides enhanced mechanical properties. The brine can be formulated to achieve specific CO2 absorption rates, and the material can be formulated with additives to further enhance its carbon-neutral performance.

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A method for utilizing waste fresh cement slurry as a mineral admixture in construction, particularly in concrete production. The process involves carbonizing the waste slurry through controlled CO2 injection, followed by mechanical treatment to produce a stabilized, carbon-based material that can be used as a replacement for conventional cement in concrete formulations. This approach addresses the environmental and operational challenges associated with traditional cement disposal and recycling methods.

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Alkali-activated low-carbon regenerated putty powder for building exterior wall coatings that combines waste concrete regeneration with sustainable cement production. The powder is prepared by mixing Portland cement, gray calcium, and waste concrete material with a specialized activator blend, followed by controlled hydration to form a durable, low-carbon cementitious material. The resulting powder exhibits improved mechanical properties and reduced environmental impact compared to conventional cement-based materials.

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Sintering-free solid waste-based low-carbon, low-alkali white cement that can be produced through the recycling of refractory organic and inorganic waste materials. The cement utilizes a unique combination of solid waste-derived gelling agents, zeolite-like minerals, and nano-silica sol to create a high-performance, low-alkali cement that addresses the challenges of white cement production, particularly in decorative applications. The cement achieves its strength through the synergistic effects of these waste-derived components, which provide a robust bonding system while minimizing environmental impact.

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Recycled concrete produced through the controlled crushing of waste concrete, cement, and water, resulting in a material with superior strength and durability compared to conventional concrete. The process involves crushing the waste concrete into a uniform aggregate, followed by cement and water mixing to create a composite material. This composite material is then processed through controlled crushing and separation steps to produce a high-quality recycled concrete product.

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A method for designing the optimal mix ratio of building mortar prepared from fully recycled fine aggregate, enabling complete replacement of river sand in traditional mortar production. The method employs a controlled trial approach to determine the precise mix ratio of fully recycled fine aggregate (FRA) to water, based on the specific strength of the mortar to be produced. The trial strength of the mortar is calculated using a standardized formula, with the strength of the mortar grade being specified. The method ensures optimal performance by matching the mortar's strength to the desired grade, while minimizing the impact of water absorption and setting time. This approach enables the production of mortar with improved mechanical properties, comparable to those of river sand-based mortars.

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Recyclable cement made from waste concrete that enables closing the cement cycle by using all components of waste concrete as raw material. The cement composition is optimized to overcome challenges like low reactivity of quartz and high magnesium content. The cement contains waste concrete powder along with a conditioning material like silica or limestone. The conditioning material mass is limited to 10% to avoid excessive additions. This allows full recycling of waste concrete without landfilling. The cement preparation involves crushing and grinding waste concrete, adding the conditioning material, sintering clinker, molding, and carbonization curing to produce the recyclable cement.

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A method for producing recycled cement from waste concrete through a novel approach that eliminates the need for limestone and other binding agents. The process involves a combination of waste concrete, high-purity alumina, and other supplementary materials to create a cement that can be used as a binder in concrete applications. The cement achieves superior mechanical properties compared to conventional cement while maintaining its environmental benefits.

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Environmentally friendly green recycled concrete material that combines old cement and glass aggregates with specialized additives to enhance their durability. The material comprises 100-150 parts of old cement block coarse aggregates, 60-90 parts of glass fine aggregates, 20 parts of adhesive, 30 parts of water, 20 parts of crack resistance enhancers, and 10 parts of water reducing agents.

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Sustainable concrete with improved workability and durability, comprising Portland cement, aggregates, water, additives, fibers, iron and steel slag, and white ladle furnace slag. The concrete combines recycled aggregates with these binders to achieve a dry consistency, while incorporating fibers and iron and steel slag to enhance its mechanical properties. The white ladle furnace slag contributes to the material's expansion resistance. The combination provides a reliable, workable, and durable concrete suitable for structural applications.

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A method for preparing recycled micro-powder concrete through enhanced coagulation of unhydrated cement particles from the micro-powder. The method involves using a coagulation process to rehydrate and reactivate the unhydrated cement particles, thereby improving the performance of recycled micro-powder concrete while addressing environmental concerns.

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A method for preparing fully recycled concrete through controlled aggregate gradation during the recycling process. The method involves a continuous process where crushed concrete is fed into a belt scale, which measures the particle size distribution. The belt scale continuously monitors the particle size distribution and automatically controls the mixing of recycled aggregates to maintain consistent gradation. This controlled gradation enables the production of fully recycled concrete with uniform particle sizes, eliminating the need for separate screening and silo mixing.

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A method for improving the performance of recycled concrete by enhancing its workability and compressive strength. The method involves mixing air-entraining agents, cement, water reducers, and surfactants into the recycled concrete mixture to create a more fluid and workable concrete. The surfactants, particularly polycarboxylate superplasticizer and sodium dodecylbenzene sulfonate, enhance the mixture's rheological properties, while the cement and water reducers improve its workability and compressive strength. This approach addresses the environmental and performance limitations of traditional recycled concrete by addressing its fluidity and workability issues.

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