Application of marble dust and ground granulated blast-furnace slag in emulsified asphalt warm mixtures

Abstract

Warm mix asphalt (WMA) has the advantage of lower production temperature as compared to conventional hot mix asphalt (HMA). It is prepared by using various types of technologies which change the properties of bitumen binder attributes to ease in workability of the mixes. In the present study, bitumen emulsion was used for preparing WMA mixes by pre-coating the aggregates. Moreover, the conventional filler used in such mixes was replaced with industrial wastes to further reap environmental benefits. Marble dust (MD) and ground granulated blast-furnace slag (GGBS) are generated abundantly and disposal is a big issue. These were used in varying contents (i.e. from 2% to 8% by the weight of mix) and WMA properties were evaluated for strength and durability. Marshall properties and indirect tensile strength test (ITS) were carried out for strength evaluation. The tensile strength ratio (TSR) was conducted asperAASHTO T 283 for durability analysis. The wheel tracker test was performed for rutting analysis. Cantabro loss was determined to assess the cohesion resistance of the asphalt mixtures. Scanning electron microscopy (SEM) images were used to assess the microscopic characteristics of WMA and its constituents. The results revealed that the inclusion of both MD and GGBS as fillers into WMA had significantly improved the stability, tensile strength, TSR, rutting and Cantabro loss results as compared to the control mix. However, the addition of GGBS filler in emulsified warm mixes showed better resistance to moisture too. Lower rut depth was observed using GGBS as compared to marble dust filler. The statistical analysis reported that there was a significant difference between stability and TSR values whereas for adhesion loss it showed insignificant difference between the GGBS and MD based mixes.