Use of waste crushed glass for the production of hot-mix asphalt

Abstract

The Council for Scientific and Industrial Research have initiated a study to develop sustainable asphalt mixes that use locally available waste materials as an aggregate replacement to reduce the material cost while improving performance. This paper presents the development and evaluation of a new asphalt concrete mix that utilizes a sustainable crushed glass as a replacement material of a natural aggregate. The ultimate goal is to produce a cost-effective asphalt wearing course with comparative performance characteristics with a conventional asphalt wearing course (reference mix) commonly used on South African roads. The paper details the mix design process of a 9.5 mm nominal maximum wearing course glass asphalt with a design traffic level of 30 million ESALs. Laboratory tests were conducted on the mix, as well as on the component materials to compare results with the volumetric design criteria set in the new asphalt mix design method for South Africa. Based on the mix design, an optimum binder content of the glass asphalt mix was 5.1%, which is similar to the 5.0% optimum binder content of the reference mix. Using the optimum binder content, the volumetric properties of the glass mix was analysed. The results indicate that the glass asphalt mix meets the South African criteria, thus the mix design is acceptable. The results of performance-related tests indicated that the tensile strength and durability properties of the glass asphalt mix are comparable to the reference mix.