Abstract
During the past two decades, geopolymer concrete has been investigated as a sustainable alternative to Portland cement concrete, which is known to generate a huge amount of CO2 in the environment. This study focuses on the assessment of the fresh and hardened mechanical properties and durability of metakaolin (MK)-based geopolymer rubberized concrete. Crumb rubber was derived from discarded waste tires, another pollution source to the environment, and incorporated in concrete as fine aggregate replacement in ratios from 10 to 50% by volume. The performance of the MK-based geopolymer rubberized concrete is discussed based on its workability, air content, stress-strain behavior (including compressive strength and modulus of elasticity), flexural strength, dry unit weight and rapid chloride penetrability. The results show that the proposed sustainable concrete mixes achieve acceptable fresh and hardened mechanical and durability properties. The compressive strength when crumb rubber replaces fine aggregates in volumetric percentages between 10 and 40% are in the range of 28.7-39.7 MPa. Furthermore, the unit weight and modulus of elasticity of the MK-based geopolymer rubberized concrete mix with 40% rubber replacement are 14.9 GPa and 2134 kg/m(3), respectively. This can promote a potentially large market for the MK-based geopolymer rubberized concrete products in applications where the priority is for decreasing self-weight and increasing flexibility rather than strength.