Pico-Cortés Carlos, Villagrán-Zaccardi Yury
Multidisciplinary Training Laboratory for Technological Research (LEMIT), National Scientific and Technical Research Council (CONICET), Centro Científico Tecnológico La Plata, La Plata 1900, Argentina.
Sustainable Materials, Flemish Institute for Technological Research (VITO), Boeretang 200, 2400 Mol, Belgium.
Materials (Basel). 2023 Aug 19;16(16):5692. doi: 10.3390/ma16165692.
Recycled aggregate concrete (RAC) includes recycled concrete aggregates (coarse and/or fine) as substitutes for natural aggregates as an approach to achieving a circular economy. Some concerns remain about its performance, including the carbonation resistance. The higher porosity of recycled concrete aggregates is logically a disadvantage, but the analysis must address many other factors. This paper provides an in-depth examination of recent advances in the carbonation performance of RAC. The emphasis is on factors that influence CO diffusion and the carbonation rate, e.g., the replacement ratio, source concrete quality, interfacial transition zone features, residual portlandite content, and porosity. The influences of previous treatments, combined action with supplementary cementitious materials, and loading conditions are also discussed. The replacement ratio has a significant impact on the carbonation performance of concrete, but it is also dependent on other factors. During carbonation, the physical effects of the porosity of the aggregate and the physical-chemical effects of the portlandite content in the adhered mortar are particularly important. The residual portlandite is especially significant because it is the primary hydration product responsible for the alkaline reserve for carbonation and the potential pozzolanic reaction, which are per se competing factors that determine the carbonation rate.
再生骨料混凝土（RAC）包含再生混凝土骨料（粗骨料和/或细骨料），作为天然骨料的替代品，以此来实现循环经济。人们对其性能仍存在一些担忧，包括抗碳化性能。再生混凝土骨料较高的孔隙率从逻辑上讲是一个劣势，但分析必须考虑许多其他因素。本文深入探讨了再生骨料混凝土碳化性能的最新进展。重点在于影响二氧化碳扩散和碳化速率的因素，例如替代率、源混凝土质量、界面过渡区特性、残余氢氧化钙含量和孔隙率。还讨论了先前处理、与辅助胶凝材料的联合作用以及加载条件的影响。替代率对混凝土的碳化性能有显著影响，但它也取决于其他因素。在碳化过程中，骨料孔隙率的物理效应以及附着砂浆中氢氧化钙含量的物理化学效应尤为重要。残余氢氧化钙尤为显著，因为它是负责碳化碱性储备和潜在火山灰反应的主要水化产物，而这本身就是决定碳化速率的相互竞争的因素。
