The effect of trass and fly ash in minimizing alkali-carbonate reaction in concrete

The influence of natural pozzolans on the controlling of the alkali-carbonate reaction (ACR) and the alkali-silica reaction (ASR) has not been studied comprehensively, regardless of the research studies conducted on utilizing natural pozzolans as supplementary cementitious materials. Nevertheless, the performance of natural pozzolans toward the ACR and ASR was investigated in recent studies. The primary purpose of this research is to evaluate the alkali-carbonate expansion of mortar specimens, which contain trass and fly ash in the short-term. For the short-term, the extent of expansion due to ACR was monitored for fourteen 7-day intervals. Based on the test result, fly ash and trass meaningfully reduced the expansion due to ACR in the short-term. Moreover, long-term test results for trass were presented as well. For the long-term, samples were kept at 80 °C in NaOH solution for curing in 56 days according to ASTM C1260 and 390 days according to ASTM C1293. The observations by optical microscopy have been conducted on thin sections.