Valorization and Upcycling the Concrete waste - a path toward net zero

混凝土是世界上仅次于水的最常用材料，占全球二氧化碳排放量的8%。这些排放物大部分来自于水泥，而水泥是用来增强混凝土强度的。与此同时，英国的混凝土行业每年从采石场和河床中提取1.8亿吨天然骨料（沙子/砾石），对环境产生巨大的负面影响。英国每年还从旧的、被拆除的建筑物中产生4500万吨“废弃”混凝土。混凝土通过一种称为“碳化”的化学过程吸收二氧化碳，从而增加其强度。混凝土碳化很少自然发生，因为它需要特定的温度，相对湿度，并且可能需要100多年才能发生。报废混凝土具有吸收大量二氧化碳的巨大潜力，并可替代天然骨料生产新的混凝土。然而，拆除后的报废混凝土是非常多孔的，因此新混凝土的强度总是低于标准。因此，英国的混凝土/建筑行业在回填/排水应用中降低了报废混凝土的使用寿命。该项目旨在开发新的CO2吸收骨料，这些骨料由来自拆除建筑物的破碎的升级回收的报废混凝土制成。我们拥有一项创新技术，可将二氧化碳封存到报废混凝土中（30% btw），并将碳化时间缩短至约100小时，而不是数年。通过加速碳化，我们可以a）降低拆除后的报废混凝土的孔隙率，B）提高新混凝土的强度和耐久性，以及c）在生产用于结构应用的新混凝土时，用压碎的报废混凝土代替天然骨料。我们的技术通过对混凝土的性能进行评估并将二氧化碳封存到混凝土中，使其在大规模生产中具有经济可行性。我们的方法是将废弃混凝土进行再生，并向其中注入二氧化碳，使混凝土成为一种非常低排放的材料。英国致力于大型基础设施项目（HS 2，Sizewell C，因此对混凝土的需求巨大），并在2050年之前实现净零排放。混凝土/建筑行业迫切需要采用循环经济和二氧化碳捕集技术来履行这些承诺。该项目的成果将帮助英国更快地通过再利用、减少和升级循环报废混凝土，实现净零循环经济。

Concrete, the most used material in the world after water, is responsible for 8% of global CO2 emissions. Most of such emissions come from the cement needed to give concrete its strength. At the same time, the UK's concrete industry extracts 180Mt/year of natural aggregates (sand/gravel) from our quarries and riverbeds, with huge negative environmental impact. The UK also produces 45Mt/year of 'waste' concrete from old, demolished buildings. Concrete absorbs CO2 through a chemical process called 'carbonation', which increases its strength. Concrete carbonation rarely happens naturally as it needs specific temperature, relative humidity, and can take 100+ years to occur. End-of-life concrete has huge potential to absorb significant amounts of CO2 and to be replace natural aggregates to produce new concretes. However, end-of-life concrete from demolition is very porous, and thus the strength of the new concrete is always below standards. Therefore the UK's concrete/construction industry downcycles end-of-life concrete in backfill/drainage applications.This project aims to develop new CO2-absorbing aggregates made of crushed upcycled end-of-life concrete from demolished buildings. We have an innovative technology that sequesters CO2 into end-of-life concrete (30% btw) and reduces carbonation time to around 100 hours, instead of years. By speeding up carbonation, we can a) reduce the porosity of end-of-life concrete from demolition, b) increase the strength and durability of new concrete, and c) replace natural aggregates with crushed end-of-life concrete in the production of new concrete for structural applications. Valorising the properties of end-of-life concrete and sequestering CO2 into it allows our technology to be economically viable at large scale. Our approach recycles end-of-life concrete and injects CO2 into it, making concrete a very low-emission material.The UK is committed to large infrastructure projects (HS2, Sizewell C, thus huge demand for concrete) and to reach net-zero by 2050\. The concrete/construction industry urgently needs to adopt circular economy and CO2-capture technologies to deliver such commitments. The results of this project will help the UK move faster to a net-zero circular economy by reusing, reducing and upcycling end-of-life concrete.