Cement is the world’s most widely consumed man-made material and it contributes between 5% and 10% of the total annual anthropogenic CO₂ emissions. Here, we report on a new method for producing crystalline calcium silicate hydrate (CCSH) phases with low lifecycle carbon emissions. The materials were made by curing silicate feedstocks, principally pseudowollastonite (CaSiO₃), under elevated partial pressures of CO₂ in buffered aqueous solutions. CCSH mortars cured for 7 days achieved compressive strength of 13.9 MPa, which is comparable to the 28-day strength of Type-S ordinary Portland cement mortars. Bromine diffusivity tests, used as an indicator of durability of the materials, show that CCSH mortars have significantly lower diffusivity than ordinary Portland cement. The resistance to dissolution at low pH of the materials was measured using acid exposure tests and found that CCSH mortar lost only 3.1% of its mass compared to 12.1% in OPC. Total carbon measurements showed that these materials can sequester between 169 and 338 g of CO₂ per kg of cement, as opposed to ordinary Portland cement, which emits nearly 1000 g of CO₂ per kg, indicating this calcium silicate carbonation process could be enabling chemistry for all-new low-carbon and high-performance infrastructure materials.

中文翻译：

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用硅酸钙碳酸化合成高性能低碳水泥的可行性

水泥是世界上应用最为广泛的人造材料，它5％，年度总人为二氧化碳的10％的贡献₂排放量。在这里，我们报告了一种生产具有低生命周期碳排放的结晶硅酸钙水合物（CCSH）相的新方法。该材料是通过在较高的CO ₂分压下固化硅酸盐原料（主要是伪硅灰石（CaSiO ₃））制成的。在缓冲水溶液中。固化7天的CCSH砂浆的抗压强度为13.9 MPa，与Type-S普通硅酸盐水泥砂浆的28天强度相当。用作材料耐久性指标的溴扩散性测试表明，CCSH砂浆的扩散性明显低于普通硅酸盐水泥。使用酸暴露测试测量了材料在低pH下的抗溶解性，发现CCSH砂浆仅损失其质量的3.1％，而在OPC中损失了12.1％。总碳测量结果表明，这些材料可以螯合克CO的169和338之间₂每公斤水泥，相对于普通的波特兰水泥，其发射近千克的CO ₂ 每公斤，表明这种硅酸钙碳酸化过程可能使全新的低碳和高性能基础设施材料成为可能。