Determination of Alkali Silica Reactivity (Asr) Potential of Aggregates in Khairpur Region

Abstract

Concrete's durability is affected by a range of factors. Alkali Silica Reaction (ASR) is one of such mechanisms that adversely impacts Concrete's durability and reduces its service life. The Reaction of reactive Silica (present in specific aggregates) and alkalis (present in Cement) begets ASR. The disturbed internal structure of Aggregate has a strong penchant for reactivity. In the presence of moisture, the Reaction produces a hygroscopic gel around the aggregate surface, which absorbs more moisture. As a result, the gel volume increases. The process engenders microcracking in Concrete. It propagates to the surface and takes the shape of 'map cracking'. This research work focuses on assessing the reactivity potential of Coarse Aggregates taken from two quarry sites of Kot Banglo, Khairpur region. The aggregates are washed and crushed. They are tested with Ordinary Portland Cement (OPC). ASTM 1260 test procedure was employed to check the reactivity potential of aggregates. The 14-day expansion of mortar bars (specimen dimension 25mm x 25mm x 285mm) was less than 0.1%. According to ASTM 1260, the result validates the innocuous characteristic of aggregates.