A Study of Early Age Properties and Abrasion Resistance of Recycled Aggregate Concrete Using High Early Strength Cement

Abstract

Modern construction techniques have enabled the concrete structures to be constructed and put into service in a very short time. These techniques include, but not limited to, the use of high early strength cement (HESC) and application of steam curing. Further, the progressively increasing demand for sustainable development has led the researchers to study the properties of recycled aggregates (RA) generated from the demolished and wasted concrete, and the concrete so produced by incorporating these aggregates termed as recycled aggregate concrete (RAC). Sufficient data is available on the early-age properties of concrete made by using ordinary Portland cement (OPC) but findings on the behavior of concrete incorporating RA and HESC at an early age, are almost none. These early-age properties of concrete are time-dependent involving hydration accompanied by volumetric changes, thus increasing susceptibility to cracking eventually affecting the long-term properties of concrete. It is, therefore, imperative to study these properties at length, to help the designers in designing the mix proportions as well the structures. This thesis examines the early-age properties of RAC made by using HESC and subjected to steam curing. Different concrete properties, including compressive strength, shrinkage, and abrasion resistance were investigated. Further, these properties were compared with those of the concrete made by OPC. It is found that compressive strength decreased, whereas the shrinkage strain and abrasion resistance increased, with increase of recycled aggregate content. Also, it is observed that the recycled aggregates are a bit harmful for strength and shrinkage properties, but these are extremely beneficial against abrasion. Finally, cost-benefit analysis was done and it is concluded that concrete made by using OPC, natural coarse aggregate, and recycled fine aggregate is the most reasonable mix for ordinary strength requirements.