Volatility of the platinum group of metals : Sir W. Crookes. ( Roy. Soc. Proc. A 1xxxvi, 461)

Abstract

Rising energy costs and increased awareness of emission problems in the production of Hot Mix Asphalt (HMA) have brought attention to the potential benefits of Warm Mix Asphalt (WMA) in India. Warm-mix asphalt is the generic term for a variety of technologies that allow the producers of hot-mix asphalt pavement material to lower the temperatures at which the material is mixed and placed on the road. Crumb Rubber Modified Bitumen (CRMB) is a popular binder in India. CRMB is composed of bitumen binder and tyre rubber. Tyre rubber, at various percentages, is added to the binder, addition of tyre rubber into binder results in a new product, which requires higher mixing temperatures compared to the conventional one, as well as increased mixing time, so as to get the uniformity of the product.A laboratory study was conducted at CSIR-Central Road Research Institute (CRRI) to investigate, how a commercially available chemical additive can be used to bring down the mixing and compaction temperature of CRMB mix as compared to the hot mix CRMB. Four different temperature ranges were considered in this study viz 1000C to 1050C, 1100C to 1150C, 1200C to 1250C and 1300C to 1350C to determine the various performance characteristics. The CRMB bituminous mix was prepared in these four temperature ranges and various mix tests were carried out to indicate to how the lower production and compaction temperatures affect the properties and performance characteristics of the mixes. After the laboratory evaluation it was found that CRMB Warm mix can be successfully produced at temperature as low as 110 °C and can be compacted at 80- 900C as compared to CRMB hot mix (155 °C). Full scale performance study indicate that process is highly energy efficient and environment friendly, warm mixes performed equivalent to “Hot Bituminous Mixes” and indicated encouraging results. After laboratory evaluation, a test track was successfully laid using low energy Crumb Rubber Modified Bitumen.