Design and Economic Evaluation of a Rubber Modified Asphalt Plant in Trinidad and Tobago

Abstract

The issue of management of waste rubber from used vehicle tyres presents major social, environmental and economic challenges for Small Island Developing States (SIDS) such as Trinidad and Tobago. Such challenges arise mainly due to associated negative effects on aesthetics, public health and ecosystems.  A possible mitigation strategy involves the blending of used tyres in the form of Crumb Rubber (CR) with asphaltic binders for road paving. Laboratory studies demonstrated that the addition of 5% CR wt of particle size ≤250 μm enhanced the performance attributes of rutting, aging, and cracking resistance of the indigenous paving materials Trinidad Lake Asphalt (TLA) and Trinidad Petroleum Bitumen (TPB). Accordingly, a rubber-asphalt processing facility was designed to examine different processing capacities up to 800,000 scrap tyres per year and utilizing different machine specifications. The plant design utilized the ambient process for CR formation and the wet process for the blending process. At a production of 714kg/hr., crumb rubber with 300 production days and a daily production rate of 12 hours, the Net Present Value (NPV) was found to be about $4.3 million for the assumed opportunity cost of 10% of the capital cost. In addition, the internal rate of return (IRR) is 49% with a payback period of 4 years. Such a facility is an economically beneficial and feasible venture presenting a sustainable disposal strategy for waste tyres and one that should be duly considered for implementation.