Tensile-Tear cracking resistance of RAP incorporated asphalt Mixtures, enhanced by Warm mix asphalt additive and nano calcium carbonate

Abstract

Asphalt mixture is a commonly used material for road paving. However, its production is expensive and requires significant amounts of virgin materials. To address this issue, adopting a less harmful production process and incorporating recycled materials can be beneficial. In this study, the focus was on investigating the cracking resistance parameters of warm mix asphalt (WMA) mixtures prepared with high contents of reclaimed asphalt pavement (RAP), along with the use of nano calcium carbonate (NC) as a modifier. In this context, the cracking resistance of the mixtures was studied in two −12 and + 25 °C temperatures under pure mode I, two mixed modes I/III, and pure mode III loading. The results revealed that adding RAP increased the fracture toughness and fracture energy, with an average increase of 30 and 20 %, respectively. Incorporating NC also improved the mixture’s resistance to cracking, enhancing fracture energy by up to 30 % and fracture toughness by up to 20 %. The optimal content of NC was determined to be in the range of 2 to 4 %, depending on the variables considered. Considering the linear elastic fracture mechanics, several theoretical criteria were used to predict the fracture data, and accurate predictions were achieved. Statistical analyses were also conducted to evaluate the impact of variables on cracking resistance; as an example of outcomes, it is seen fracture energy of pure mode III is about twice the mode mode I.