Cracking Resistance of Cold Bitumen Emulsion Mix Containing Different Fillers

Abstract

Despite being economically and environmentally friendly, the use of cold bitumen emulsion mix (CBEM) is still limited to minor repair work and construction of low volume roads. One of the reasons behind this underutilization is its poor cracking resistance. Fillers have significant effects on the cracking resistance of asphalt mixes. So, the present study aims at examining the effect of different fillers, i.e., stone dust, cement, lime, fly ash (FA), and ground granulated blast furnace slag (GGBFS) on the cracking resistance of CBEM. The cracking resistance of CBEM was examined by indirect tensile strength (ITS) and semicircular bending (SCB) tests. Results showed that the inclusion of active as well as waste fillers significantly improved the cracking resistance of all modified CBEM. However, the cracking resistance developed by FA and GGBFS modified CBEM were not comparable to cement modified CBEM. So for further modification, lime was added to FA and GGBFS modified CBEM, which further enhanced the cracking resistance of CBEM, making it comparable to that of cement modified CBEM. This experimental study was further extended to examine the effect of these fillers on the properties of cold bitumen emulsion mastic (CBEMa) by conducting scanning electron microscopy (SEM), X-ray diffraction (XRD), and linear amplitude sweep (LAS) tests. The SEM and XRD results confirms the presence of hydration products in the mastic phase of CBEM. In addition, a Pearson correlation analysis was carried out between the LAS parameters of CBEMa and the cracking resistance parameters of CBEM, confirming a linear association between both characteristics. Cold mix asphalt or cold bitumen emulsion mix is a cost-effective, emerging pavement construction practice. Unlike traditional hot mix asphalt, cold bitumen emulsion mix is prepared at ambient temperature, requiring minimal energy consumption during production and transportation, which makes it suitable to be used in colder weather conditions. However, due to its poor early strength and poor performance, its application areas are limited to constructing low-volume roads and pavement maintenance works. The presence of water in the compacted mix is the primary cause of poor early strength in cold bitumen emulsion mix. Nowadays, researchers are investigating various methods to improve its performance and expanding its applications. This study promotes the use of fillers such as cement, lime, fly ash (FA), and ground granulated blast furnace slag, as well as their combinations, in order to mitigate one of the recognized pavement distresses, i.e., cracking failure. These fillers provide hydraulic behavior in the presence of water in the compacted mix, facilitating a secondary binding network. This additional binding network strengthens the mixes and reduces crack propagation. This in-depth study will inspire politicians, policymakers, and transport officials to consider the benefits of this technology and implement it in the field.