Mechanical Properties of Concrete Made of Crushed Concrete Subjected to Different Fire Durations (Dept.C)

Abstract

The amount of construction and demolition waste has increased considerably over the last few years. The heaviest materials found in construction and demolition waste are rocks, concrete and ceramic residues. Nowadays, almost all demolished concrete has been mostly dumped to landfills. From the viewpoint of environmental preservation and effective utilization of resources, the interest in using recycled materials derived from construction and demolition waste is growing all over the world. Crushing concrete to produce coarse arrregate for the production of new concrete is one common means for achieving a more environment-friendly concrete. This reduces the consumption of the natural resources as well as the consumption of the landfills required for waste concrete. From the durability point of view, the performance of recycled concrete exposed to fire or high temperatures is not a very well-known subject since this property has been widely studied on conventional concretes. Such performance is related to the temperature level reached at the surface and interior of the material, the time of exposure. Also, the concrete's own characteristics such as w/c ratio, type of natural aggregate used. In the experimental work, the fresh properties (slump test) and the hardened properties, (compressive strength, splitting tensile strength, and flexural strength) were carried out. A total of thirty concrete mixes with different cement contents (300, 350, and 400 Kg/m3) at w/c ratio (0.5) were made and the percentag of substitution of natural narse aggregate by the recycled concrete aggregate subjected sto fire temperature 600°C for (1, 2, and 3 hours) was (0%, 25%, 50% and 100%). In the process of mixing, equal consistence among all concrete mixes was achieved. The obtained results indicate that the recycled coarse aggregate subjected to fire can successfully be used for making structural concrete.