EFFECT OF FILLERS IN PERFORMANCE OF COLD MIX FOR BM AND DBM COURSES

Abstract

Cold Mix Asphalt (CMA) is one of the most acceptable sustainable (green) technology for constructing flexible pavements that has gained prominence owing to lower production temperatures. The present research investigates different fillers such as cement, fly ash (FA), and Stabil-road (SR) in varying proportions ranging from 0% to 3% (with equal increment of 1%). One control cold mix with 1.5% water content and 6.6% asphalt residue and nine respective mixes with variable filler contents were prepared and tested according to the relevant standard codes. The bituminous cold mix is used for low-volume roads with mineral fillers, and it is a type of CMA, but by using FA and SR, the strength and workability of the mix can be improved, and the mineral filler can be replaced by industrial waste. Cold mix asphalt is a greener alternative technology used in pavement construction, which utilizes only 10 - 40˚C of heat, typically lower than other techniques like warm mix asphalt (WMA) and hot mix asphalt (HMA). Huge amounts of construction and demolition waste, such as broken bricks, recycled concrete aggregates, reclaimed asphalt pavement (RAP), ceramic waste, etc., are generated yearly due to the acceleration of infrastructure development. The production of such massive amounts causes landfilling issues, and their disposal is a serious challenge nowadays. This study evaluated asphalt mixes produced using emulsified binders and 50% reclaimed pavement materials. The moisture susceptibility of the recycled cold mix asphalt (RCMA) mixture was evaluated using the tensile strength ratio. Cantabro abrasion loss was used to assess the cohesion resistance of the mixtures. The dynamic response of the mixes to the applied load was evaluated using resilient modulus (Mr). Experimental results highlighted that the Marshall stability of the CMA with 3% cement was 22% higher than that of the control cold mixtures. Furthermore, considerable improvement in strength and inter-particle bonding were observed with the inclusion of binary blended filler (BBF) in the considered cold mix and RCMA. BBF incorporation enhanced the performance of the recycled cold mix asphalt. The utilization of RAP materials in the construction and maintenance of flexible pavement with asphalt emulsion is a sustainable approach. RAP is used as aggregate in CMA design instead of virgin aggregate, saving more energy than HMA. The focus of the RAP utilization in the research study is (i) virgin aggregate production, (ii) the utilization of waste material (additive), (iii) reducing the production temperature, and (iv) recycled RAP material in the pavement. Cold mix asphalt containing 0%, 50%, and 100% RAP materials with different dosages of additives was used to ascertain the mechanical and volumetric properties of mixtures. All the additives can potentially resist moisture damage in the mix. Also, a significant improvement in the resilient modulus was considered for RAP-incorporated mixtures with the additives. The mechanical properties of the designed CMA depend on the mixing of aggregates, prewetting water content, bitumen emulsion, curing time, voids, and pulse repetition periods. Significant reductions in production temperature and enhanced service life are some of the study’s outcomes. Research is being conducted to advance sustainable practices for road pavements; foamed asphalt mixes (FMA) have become a valid option for common asphalt for standard technologies. The FMA is a type of cold mixture, and is used for low-volume roads, but its strength and workability are improved using additives. It reduces the environmental impact during the life cycle of the road pavement. The voids of the FMA mix were selected to be 10-14% higher than the HMA mix. Also, it was observed that the resilient modulus increment reduced with the pulse repetition period. Foamed mix asphalt is a unique pavement construction method for enhancing new granular materials. Cold water and air molecules are injected into the Wirtgen WLB 10S machine's bitumen expansion chamber to produce foamed bitumen. When hot bitumen mixes with cold water, foam is produced, and bitumen bubbles appear during the instantaneous foaming process. The binder collected in a cylindrical bucket during foaming is foamed bitumen (FB), and FB has a low viscosity. Fundamental indicators of FMA are expansion ratio and half-life. This research reflects the life cycle analysis (LCA) of CMA to hot mix based on different parameters like energy consumption and carbon emission in the cradle-to-gate stages, incorporating the effects of various foaming agent contents. Also, the LCA method estimates greenhouse gas emissions responsible for global warming at different stages of production, transport, and pavement laying at the site. Today, there are so many significant challenges, such as global warming. Adopting CMA and FMA technology in the design of road construction may reduce these challenges. Using different additives in different proportions can improve the strength and workability of the CMA and FMA technology.