The investigation of alkali silica reaction of mortars containing borogypsum

Abstract

In this study, various properties and the alkali silica reaction (ASR) of mortars containing borogypsum were investigated. In the first stage a complete physical, chemical, mineralogical, molecular characterization of the borogypsum and cement were performed. In the second stage, the alkali silica reaction, mechanical and porosity properties of mortars, replacement 0, 1, 2, 3 and 4% borogypsum by weight were determined. According to experimental result, from a mineralogical perspective, the borogypsum was observed to have a sharp crystal structure and possess a mineralogical composition of calcite, colemanite and celestine. Looking from a molecular perspective, the similar OH, CaO, B–OH and H–OH bonds were displayed in the close wavenumbers. As the results of 14 days measurements were analyzed, the average maximum length extension was detected to be in the control mortar bars and at the detrimental zone from the ASR perspective. The average minimum length extension at the borogypsum with a additive rate of 3 and 4%, was observed to be at the control zone from ASR perspective. The lowest strength loss in mortars exposed to ASR effect occured in those with substitution level of 3% borogypsum. When the flexural strength of mortars exposed to ASR effect was examined, the increase in strength was observed for borogypsum with all substitution levels (1–4%). The maximum recovery concerning the minimum volume of mercury intruding the sample and vacancy rate was observed for the substitution level 3% borogypsum.