Date of Degree
MS (Master of Science)
Civil and Environmental Engineering
Hosin David Lee
Hot Mix Asphalt (HMA) has been used over the years for laying roads. It required the aggregate and the binder to be heated to temperatures above 160°C (320°F). Heating the aggregate and binder in large quantities consumed a lot of fuel. This called for alternative solutions in the technology of laying roads. This brought about a new technology called Warm Mix Asphalt (WMA). WMA is an emerging technology that can allow asphalt to be produced and compacted at a significantly lower temperature. In the past, a number of researchers evaluated various WMA mixtures using selected testing procedures in the laboratory. However, none of them evaluated all the major WMA products and compared them with WMA mixtures without an additive using a comprehensive set of testing protocols. This paper presents a comprehensive evaluation result of three major WMA additives (Sasobit®, Evotherm J1 and RedisetTM) regarding their viscosity, tensile strength, moisture sensitivity, dynamic modulus and flow number. These three additives were chosen since all of them are prepared from a base wax product.
The asphalt showed a decreasing trend in viscosity with increase in the concentration of the additives. The WMA specimen with additives exhibits similar air voids as control WMA specimens which indicate these WMA additives are effective in compacting asphalt mixtures at low temperatures. The Indirect Tensile Strengths (ITS) and Tensile Strength Ratio (TSR) values of the WMA specimen with admixtures were found to be higher than the control WMA specimens. This result indicates that the admixtures play a significant role in enhancing the properties of WMA. WMA mixtures with additives exhibited higher dynamic modulus than the control WMA at all temperatures. All the specimens passed the requirement of 10,000 cycles of repeated loading. The WMA specimen with Sasobit® additive exhibited the lowest permanent deformation. Based on overall test results it can be concluded that Sasobit®, Evotherm J1 and RedisetTM WMA additives are effective in producing WMA mixtures in the laboratory which have high strengths.
Copyright 2010 Anand Sampath
Sampath, Anand. "Comprehensive evaluation of four warm asphalt mixture regarding viscosity, tensile strength, moisture sensitivity, dynamic modulus and flow number." thesis, University of Iowa, 2010.