Utilizing Scrap Tyre in Unbound Pavement Layers: A State-of-the-Art Review

Escalating scrap tyre generation and its disposal have been of concern as these cause detrimental impacts on the environment. Being a non-biodegradable waste, the possible avenues to discard scrap tyres are limited. This study selectively reviewed published literature to reveal utilization prospects of scrap tyre for the construction of unbound layers of pavement. By substituting conventional materials with scrap tyres, the cost of construction could possibly be reduced. In an attempt, this article reviews the types of soil/aggregates substituted with tyre crumb, size of tyre crumb and substitution amount. Also, engineering properties and their response to the accumulation of tyre crumb are presented. In a nutshell, compaction and strength characteristics worsen at different rates depending on the size of the tyre crumb and soil/aggregate type. On the contrary, hydraulic conductivity and resistance to vibratory forces improved. This kind of cost-effective construction practices benefit economically deprived nations that struggle due to budget constraints pertaining to road infrastructure development and waste disposal. This review would help researchers and practitioners to devise stringent protocols and regularize the usage of scrap tyres in road construction.