The mechanical and microstructural properties of Li2SO4, LiNO3, Li2CO3 and LiBr added mortars exposed to alkali-silica reaction

Abstract

Aim of this study intends analyzing the effects of lithium additives on fresh and hardened cement mortars. In this study, mortar specimens were prepared by adding four types of additives (Li2SO4, LiNO3, Li2CO3 and LiBr) to the mixing water of the cement at 0.5%, 1%, 1.5%, 2%, 2.5% and 3% proportions by weight. The Alkali-silica reaction (ASR) of these mixtures was explored. The effects of Li2SO4, LiNO3, Li2CO3 and LiBr, which are used to control ASR induced expansion, on expansion and mechanical properties were determined. ASTM C 1260 experiment standard was used to find out the reactivity of aggregate and cement mixtures. In this experimental study, the morphology and the chemical composition of specimens exposed to ASR effect was examined by means of scanning electron microscope (SEM) and Energy Dispersive Spectroscopy (EDS). Fourteen-day readings conducted in the experimental study showed that the average maximum length change of the reference mortar bar was 0.34%, whereas the lowest average length change was 0.023% of the mortar bar with 3% Li2CO3 additive. Among the mortars that had undergone ASR, mortars containing 3% LiNO3 experienced the least strength loss. As observed in the SEM image, EDX done on dense and wide ASR cracked areas pointed to high ratios of calcium oxide and silica oxide. (C) 2013 Elsevier Ltd. All rights reserved.