Utilization of lithium nitrate to mitigate alkali–silica reaction of architectural glass mortar: Characteristics and mechanisms

Abstract

It is low carbon footprint and low cost to use waste glass as fine aggregate in producing architectural mortar. However, glass aggregate is prone to alkali–silica reaction (ASR), which causes expansion and cracking of architectural mortar. Addition of LiNO3 is a good method to mitigate ASR but current understanding on characteristics of ASR reaction products and mitigation mechanisms of LiNO3 for glass aggregate are not sufficient. To contribute to the state of knowledge on these topics and promote the recycling of waste glass, this study systematically investigated morphologies and characteristics of ASR reaction products of glass mortar samples with and without LiNO3 by various microscopic analyses. The results showed that 1% LiNO3 reduced ASR expansion by 85.12% and map cracks disappeared. The formation location, characteristics and microstructures of ASR gel of glass aggregate were different from natural aggregate. The mitigation mechanisms of lithium were proposed: reduction in the dissolution of glass aggregate and the transformation from tobermorite-type to polymerized C–S–H, dense pozzolanic C–S–H serving as a physical barrier and strong lithium binding capacity to reduce Na/Si ratio of ASR gel.