Strength and durability of geopolymer concrete with high volume rubber replacement

Waste tyre disposal is increasingly challenging around the world. Innovative solutions include incorporating rubber in concrete to significantly improve the ductility and impact resistance. Rubberised geopolymer concrete (RuG) has several potential advantages over the conventional rubberised cement concrete. For example, the alkaline treatment solution is readily available as the activator, and better compatibility with rubber can be achieved due to geopolymer's lower elastic modulus. However, there is a limited number of studies on this topic. This paper experimentally investigates 10 mixes with different rubber contents, binder compositions and treatment methods to quantify various mechanical and durability properties of RuG. The applicability of a selection of popular durability tests for RuG was also assessed. Results showed that the compressive strength of RuG had a strong correlation with bulk density, elastic modulus, ductility, splitting tensile strength and water absorption. The use of the activator for both rubber treatment and binder activation did not have a significant impact on the strength of RuG compared to conventional treatment methods. This finding could be used to improve the efficiency of the RuG mix designs. This study also pointed out several possible improvements for the durability testing of RuG, such as the complementary compressive strength tests in the carbonation tests. The assessment of durability tests also provided guidance on the proper evaluation of RuG in future studies.