Development of Lightweight Rubberized Geopolymer Concrete by Using Polystyrene and Recycled Crumb-Rubber Aggregates

An environmentally friendly concrete is of high interest to develop because the production of portland cement as the main binder of conventional concrete is associated with generating a large amount of carbon dioxide. As a green and eligible alternative to conventional concrete, geopolymer concrete (GC) has been invented and studied over the past 2 decades. This experimental study was aimed to take one step further by examining the possibility of developing lightweight, rubberized, and lightweight rubberized geopolymer concrete. In the first step, a control mix was established for GC suitable to be cured at ambient temperature as it is necessary to promote its usage in the construction industry. Afterward, lightweight geopolymer concrete (LWGC) was developed by replacing fine aggregates with expanded polystyrene beads (called BST) at 25%, 50%, 75%, and 100% ratios by volume. Then rubberized geopolymer concrete (RGC) was produced by 10% and 20% natural aggregate replacement by volume with crumb rubber (CR) aggregate, which is another pollution source to the global environment. Finally, the possibility of developing lightweight rubberized geopolymer concrete (LWRGC) was examined using BST and CR aggregates. The performance of developed GCs is discussed based on slump flow, density, compressive, tensile, and flexural strength at 7 and 28 days in this paper. The optimal mix design concluded from LWGC and RGC mixes is also introduced for LWRGC with two different CR sizes (2-5 mm and 5-10 mm). The proposed green mixes showing acceptable fresh and hardened mechanical properties are able to be used in appropriate construction projects and hence reduce the need for cement manufacture as well as disposal of end life tires.