Effect of Unprocessed and Processed Recycled Aggregate on the Compressive Strength of High Strength Concrete

Abstract

The growing industrialization and rapid infrastructural development has resulted in the increased demand of concrete and especially high strength concrete. With greater than before demand for concrete the enormous quantity of natural aggregate is required for making concrete. This in turn has resulted in the depletion of the natural sources of course aggregates. Also large amounts of construction and demolition wastes are generated per year and dumping of these creates huge problem to the environment like presence of inert and non biodegradable materials, emission of carbon dioxide and scarcity of land fill areas. Also, roadside dumping causes problem to the traffic flow causing additional workload to the local administration. Thus, to tackle the above mentioned problems, the introduction of recycled aggregate comes into the picture. The study has been done in three phases: (i) using natural aggregate in making high strength concrete, (ii) use of un-processed recycled aggregate (UPRA) at 20%, 40% & 50% replacement with natural aggregate and studying its effect in attaining the required compressive strength, (iii) use of processed recycled aggregate (PRA) at 20%, 40% & 50% replacement with natural aggregate and studying its effect in attaining the required compressive strength. The processing of PRA was done using ―straight forward mechanical grinding approach‖ in which the aggregates to be processed were introduced in Los Angeles abrasion machine to get rid of the adhered mortar. Effect of different revolutions (200, 500 & 700 revolutions) on concrete boulders to produce the required compressive strength were studied for each replacement percentage (20%, 40% & 50%). Two-stage mixing approach was adopted for a homogenous mix.