Abstract:
The development of construction industry is booming with a resulting increase in requirement of concrete as an input. To produce this concrete, a huge amount of natural resources is consumed where aggregate takes the largest proportion. This high consumption of aggregates causes for the depletion of limited sources of natural aggregates and the availability of new sources. On the other hand, the construction industry development also causes for the generation of construction and demolition wastes. This leads in an increasing stockpiling and deposition with landfilling which affects the surroundings. In this paper an experimental investigation was carried out to observe the effect of recycled tyre steel fiber on the fresh and hardened properties of a concrete made with recycled coarse aggregate. Waste tyre steel wire with 50mm length and an aspect ratio of 100 are used as fiber reinforcement in a volumes fraction of, 0.5%, 1.0%, and 1.5% in recycled aggregate concrete mixes. For comparison purposes, plain control samples (NAC/control-1 and RAC-0%/control-2) are also considered. The research result shows that, at a full replacement of natural coarse aggregate by recycled coarse aggregate, the compressive and flexural strength are reduced by 18.2 and 10.2%, respectively. Workability of fresh recycled aggregate concrete is largely influenced by the presence of steel fiber; on the other hand, it was unlikely to achieve considerable improvements in compressive strength by steel fiber inclusion. Due to fibers addition, the flexural strength of recycled aggregate concrete is greatly increased, even to a greater extent than the flexural strength of conventional concrete. The addition of recycled tyre steel fiber volume up to 1.5%, the compressive and flexural strength of recycled steel fiber reinforced recycled aggregate concrete (RSFRAC) is increased by 17 and 96.2% respectively compared to plain recycled aggregate concrete. The load-deflection characteristics & cracking/failure pattern of the steel fiber reinforced recycled aggregate concrete specimens indicated to improved ductility over plain recycled aggregate concrete. The interesting results confirm the promising application of recycled aggregate concrete reinforced with steel fibers extracted from used tyres in the construction industry.