Calcined Clays for ASR Mitigation: Mechanisms and Long-term Performance

• 作 者: ChangLi[1]JasonH.Ideker[1]ThanosDrimalas[2]
• 机 构: School of Civil and Construction Engineering, Oregon State University, Corvallis OR 97330, USA
• 出 处: The 14th International Congress on the Chemistry of Cement (
• 发表日期: 2015年期

　　Previous research has shown that using metakaolin is an effective strategy for mitigation of alkali-silica reaction (ASR) in concrete.Metakaolin reduces the OH, K+ and Na+ concentrations in pore solution.The high aluminum content in metakaolin has also been reported to be effective in mitigating ASR.However, research on calcined clay of different sources and qualities is still limited.This study investigated the mechanisms of ASR suppression by using one known very highly reactive fine aggregate and four calcined clays from different sources.To determine the optimum replacement for ASR mitigation, cement was replaced by 5%, 10%, 15% and 20% of the different calcined clays and tested according to the accelerated mortar bar test (AMBT).Results indicated chemical composition and mineral phase had a significant impact on ASR mitigation efficacy.Meanwhile, to investigate the influence of the calcined clays on ASR gel, samples from mortar bars were taken at 14 days for scanning electron microscopy (SEM) analysis.The formation of ASR gel and composition of ASR gel were compared between the control mixture and the 10% calcined clay 3 (CC3) mixture.ASR gel composition was found to be mainly determined by the aggregate composition.