Mechanical, durable and acoustic properties evaluation of concrete containing granulated blast furnace slag and waste tyres aggregate

Abstract

The disposal of rubbers from the waste tyres remains the main environmental concern worldwide unless recycled in an eco-friendly way. The incorporation of these wastes into the concretes as replacement agent for some of the natural aggregates is strategized as one of the possible solutions. Based on these factors, this study evaluates the effects of the tire rubber crumb wastes (TRCWs) at various contents (5, 10, 20 and 30% of volume) and granulated blast furnace slag (GBFS) as the fine and coarse aggregates replacement on the properties of newly designed concretes. Twelve batches of such concretes are prepared by blending the industrial wastes including the GBFS and TRCWs with ordinary Portland cement (OPC). The mechanical, durability and acoustic performance of these modified concretes are analyzed using slump, compacting factor, water absorption, compressive, tensile, flexural strength, and modulus of elasticity test. Added to that the resistance to carbonation, acid, sulphate attack and elevated temperatures, as well as the microstructure tests such as scanning electron microscope (SEM), x-ray diffraction (XRD), energy dispersive x-ray (EDX), and impedance tube test. The concrete modified with 20% of GBFS as OPC replacement shows enhanced mechanical traits wherein the compressive strength after the curing age of 28 days is higher (42.8 MPa) than the OPC control mix (33.8 MPa). Moreover, the mix designed with 5% of TRCWs as fine or/and coarse aggregates replacement is nearly 14.8% compared to the OPC specimens. The results show that the TRCWs substitution up to a limit of 10% of the river sand and gravel into the concrete can be effective without any strength loss. The modified concretes’ performance in aggressive environments are analyzed using residual compressive strength, weight loss, surface textures and microstructure tests. The concrete modified with 20% of GBFS as OPC replacement shows enhanced durability properties wherein the residual compressive strength after exposed to sulfuric attack of one year is higher (10.7%) than the OPC control mix (2.9%). Moreover, the mix designed with 5% of TRCWs as fine or/and coarse aggregates replacement is nearly 7% compared to the OPC specimens. Modified concretes with 30% of TRCWs aggregates exhibit an enhancement on noise reduction coefficient (NRC) by 137.7% and lower sound transmission coefficient (STC) by 37.3% compared to the control specimen. Since the compressive strength is in an acceptable range (27MPa), modified concrete contains 30% of fine TRCWs has good potential to be utilised as an acoustic absorber as the capability of absorbing sound energy at 500 Hz to 2000 Hz has improved. Therefore, modified concrete contains 30% of fine TRCWs can be applied as a sound-absorping material for application in railway concrete slabs, precast concrete walls and concrete pavement blocks. It is established that the use of TRCWs into concrete will be an environmental remedy and renewable resource for developing construction materials, leading to sustainability (minimization of the depletion of natural resources including river sand and gravel).