Reações álcali-agregado em concretos com agregados reciclados de resíduos de construção e demolição na cidade de Campina Grande - PB.

Abstract

The Alkali-Aggregate Reaction (AAR) is a chemical process of concrete deterioration which had its first records in the beginning of the 20th century, and it was primarily identified in dams, bridges, port structures and, more recently, foundation blocks. It is basically the reaction product of alkalis in the concrete, reactive minerals in aggregates and water, and generates an expansive effect to which there is no existing solution. Due to this, prevention is the main tool available to stop AAR from occurring, therefore the aggregate reactivity, among other things, must be readily identified. Sustainability is a topic in growing evidence, and the use of aggregates from the recycling of solid residues (or Construction and Demolition Waste – CDW) is na alternative to the destination of these, thus being needed that such aggregates have their potential reactivity assessed. In this work, two CDW aggregates were tested, which were Concrete Residues and Masonry Residues. Furthermore, testing was done on sand and gravel frequently used in constructions in the city of Campina Grande – PB. The method used for testing was the Accelerated Mortar Bar Test, which is done by submerging mortar bars cast with the aggregates to be tested in a sodium hidroxyde solution heated to 80°C. Measurements of expansion of the bars, for all aggregates, were taken daily until 16 and 28 days of submersion. From the measurements obtained and the 0.10% expansion limit stablished in ABNT NBR 15577, the aggregates did not show as potentially reactive.