Optimization in producing warm mix asphalt with polymer modified binder and surfactant-wax additive

Abstract

Recently, numerous warm mix additives were developed and their influences on the properties of asphalt binders and mixtures were investigated in the field and laboratory. Although, most of the technical requirements for these materials have been accepted for individual conditions, some important questions still remain unfolds. For instance, which combinations of production parameters are referred to fabrication of an optimum product? This study presents a new potential approach to answer this question via a numerical optimization for all test responses using desirability functions. For this purpose, a surfactant-wax warm additive was used for modification of binders. A series of warm mix asphalts (WMA) specimens were fabricated using a polymer modified binder, in different compaction temperatures, additive contents and binder contents. Experiment design was planned and analysis was conducted by a statistical approach named response surface method (RSM). The price of raw materials, mechanical properties of mixtures and energy consumption for production of WMA were involved in the analysis of data. This method presented an optimum combination of decision factors including binder contents, additive contents and compaction temperatures to produce one ton WMA in different production scenarios. Although, there are different recommendations for use of additive contents, optimization process proposed 1% of additive for modification of binder for various scenarios. Possibility for simultaneous determination of binder content in combination with other factors could discard the process of traditional Marshall method to ascertain the optimum binder content.