Ultra-violet and chemical treatment of crumb rubber aggregate in a sustainable concrete mix

This paper illustrates the usage of crumb rubber as a recycled aggregate in concrete. However, the presence of crumb rubber leads to a lower concrete compressive strength primarily due to its much lower stiffness. Under stress, the rubber deforms, re-distributing the load to the cement paste, which subsequently fails prematurely. Instead of reverting to conventional methods of increasing concrete compressive strength, such as lowering the water cement ratio facilitated through the addition of a superplasticiser or enhancing the binder effectiveness with the addition of silica fume, this paper will focus on some of the pre-treatment methods on crumb rubber that can help mitigate this loss of strength. These include accelerated aging and stiffening crumb rubber through exposing it to ultraviolet light to enhance its surface roughness characteristics or pre-treating crumb rubber by soaking it in sulphuric acid to develop a stiffer surface layer. By increasing the rubber's stiffness, it is observed that its load share increases, thereby improving the crumb rubber concrete's compressive strength and allowing a larger dosage replacement of normal aggregate without significant strength loss. In summary, identifying whether or not different pre-treatment of the crumb rubber aggregates are successful in avoiding a substantial loss in strength consequent upon its inclusion in concrete is the primary objective of this paper.