USE OF PUMICE AND SCORIA AGGREGATES FOR CONTROLLING ALKALI SILICA REACTION

Abstract

Turkey has important potential pumices reserves (68% of the reserve of the world) and especially, 56 % of pumice reserve of Turkey is in the East Anatolia Region. It is important to assess huge mine, pumice, reserve in Eastern Turkey for its use in the cement and concrete industry. Use of acidic pumice and basic pumice (scoria) as cement additive or aggregate are gaining popularity because of their proven structural/durability properties. This paper presents the results of an investigation to assess the effectiveness of pumice and scoria aggregates in controlling alkali silica reaction (ASR) of alkali silica reactive aggregate using the following test methods: the accelerated mortar bar test (ASTM C 1260) and the scanning electron microscopy technique (SEM). The morphologies, structures and properties of the samples were determined by XRD, ICP-MS, XRF and thin section study. Mortar cubes were specially prepared as per ASTM standards using 10, 20 and 30% pumice or scoria aggregate as alkali silica reactive aggregate replacement. The results are then compared with ASTM requirements to assess the suitability of pumice or scoria for preventing alkali silica reactivity. According to the results of these methods, pumice aggregates control the alkali silica reaction whereas scoria aggregates decrease expansion but is not as effective as pumice in preventing ASR. The results of SEM analysis showed alkali silica gel formation and serious decomposition of aggregate texture due to ASR in scoria added mortar bars.