Enhancing the corrosion resistance of recycled aggregate concrete by incorporating waste glass powder

Conventional supplementary cementitious materials would decrease the alkalinity of pore solution, which is not beneficial for the stabilization of passive film on the surface of steel bars in the marine environment. By leverage of the alkali-rich and pozzolanic characteristics, this study first valorized waste glass powder (GP) to enhance the corrosion resistance of recycled aggregate concrete (RAC). The results showed that partially replacing cement with GP could improve the steel corrosion resistance of RAC to a level better than conventional concrete prepared with natural aggregates. Moreover, the presence of 20% GP significantly enhanced the chloride penetration resistance at a later age without sacrificing the compressive strength. The enhanced corrosion resistance of GP-RAC was attributed to two main reasons: i) the refined pore structure by the formation of secondary C-(N)-S-H gels with a lower Ca/Si ratio; ii) the increased alkalinity of pore solution due to the depolymerization of GP and the released Na⁺ from GP. As a result, the use of GP in low-carbon cement was able to compensate for the inferior durability of RAC. The proposed corrosion-resistant concrete with low ecological and economic costs has a promising application potential to promote the wider use of GP and RAC in the construction sector.