Warm mix asphalt: Paves way for energy saving

Road transport sector in India has expanded in the last sixty years after independence, both in terms of capacity and dimensions. Today, India is having thethird largest road network in the world, with over 4.236 million km of roadways spread across the country. Currently, majority of the Indian roads are paved with Hot Mix Asphalt (HMA),which consists of aggregates and bitumen mixed together at high temperature,approximately150-170°C. The production and placement of HMA pavements has evolved over the last 130 years and recognised as a high quality engineered paving material to produce good quality pavement. During all these years, the production of HMA has modernized from manual hand mixing and placement with rakes and shovels to computerized plants feeding, placement, and compaction equipment that track location and material quality.The main concern with the production of HMA is, it requires large amount of energy and also releases enormous amount of emissions into the environment. So, the road construction industry is looking for an alternate material or a technology that reduces the amount of energy required to produce the HMA, in order to combine energy savings and environmental benefits. Warm Mix Asphalt (WMA) technology is one of the solutions. WMA technologies allow producing the asphalt material at 30 to 40°C lower temperatures than conventional HMA. This paper presents a comprehensive literature review on various WMA technologies across the globe and advantages associated with WMA technologies.It also provides details of some of the attempts done with WMA technologies in India till now

Use of Industrial Wastes as Filler in Open-Graded Friction Courses

For a fast developing economy like India, expansion, rehabilitation, and maintenance of transportation infrastructure is crucial and require huge quantities of high quality natural aggregates. Meanwhile, vast amounts of industrial wastes accumulating in the country pose problems related to safe and sustainable disposal. The present study investigated possible utilisation of marble dust, a waste from stone industry, and fly ash, a waste from thermal power stations, as filler materials in open-graded friction course mixes. Open-graded friction course mixes incorporating fly ash, marble dust, and two sources of stone dust as filler fractions were designed and evaluated for mix design properties including draindown, abrasion loss, air void content, and permeability. Morphology of each filler was characterised through scanning electron microscopy. Physicochemical properties of fillers were examined through Rigden voids, German filler test, methylene blue, and hydrometer analysis. Analysis of variance using Fisher multiple comparison procedure was performed to evaluate the effect of filler type on design properties of open-graded friction course mixes. Regression analysis using forward selection technique was performed to identify significant filler characteristics influencing open-graded friction course properties. Results showed that filler type affected open-graded friction course design parameters significantly. Open-graded friction course mixes with marble dust showed promising performance with lowest draindown, and highest durability, air voids, and permeability. Regression analysis identified Rigden void content of filler materials as a major filler characteristic affecting the mix design parameters of open-graded friction course mixes