Comparative Study on the Performance of Open Graded Friction Course using Hot and Warm Mix Technology

Abstract

Conventional pavements and parking lots are constructed as impervious structures which leads to large volumes of stormwater runoff. This increases the load of stormwater drains besides the water carries the dirt and debris present on the surface and pollutes the water bodies. Surface detention basins are usually provided to collect the runoff and slow down its rate. But this requires additional land space. So, a solution in this regard is to provide a permeable pavement system that permits the infiltration of the stormwater. Open graded friction courses are provided as the surface course of such pavements. This research aims at assessing the feasibility of using warm mix technology in the production of open graded friction course mixes. The focus was on the benefits that could be acquired by the use of WMA technology in a porous asphalt mix. In this study a chemical additive namely sasobit was used to prepare warm mixes. A comparative assessment between hot and warm porous bituminous mixes was made. The fundamental parameters evaluated includes volumetric properties of the mix, permeability, drain down, Cantabro abrasion loss, and moisture susceptibility. It was found that the warm mix additive was capable of reducing the production temperature and the maximum temperature reduction was obtained in the case of 3% sasobit. About 10⁰C reduction in mixing and 13⁰C reduction in compaction temperature could be achieved. The results indicate that open graded mixes prepared with warm mix technology met the performance criteria and hence it is suitable for application in porous pavements. This reduction in temperature could be translated to reduced fuel consumption for heating the binder and reduced level of emissions. Thus, it leads to better working environment for those involved in road construction.