Mechanical and durability performance of asphalt mixtures with partial replacement of hydrated lime by calcium carbonate

One of the most widely used materials as a mineral filler in asphalt mixtures is hydrated lime (HL), due to its notable advantages in enhancing the adhesion between the binder and aggregates, reducing moisture sensitivity, and improving the mixture’s performance at high temperatures, all of which contribute to greater pavement durability. Furthermore, HL functions as an anti-stripping agent and slows down bitumen ageing, thereby optimising the mechanical properties of the mixture. However, in the Peruvian context, HL is classified as a controlled substance due to its potential use in illicit activities, resulting in restrictions on its commercialisation and transport. In light of this limitation, the present study explores the partial substitution of HL with calcium carbonate (CC) in order to maintain the technical performance of the mixture while reducing production costs. Asphalt mixtures were evaluated in which the conventional HL content (1.5 % by aggregate weight) was replaced with CC at substitution levels of 25 %, 50 %, 75 %, and 100 %. The fillers were characterised based on their chemical composition, mineralogy, and particle size distribution, and five asphalt mixtures were designed. The evaluation included measurements of bulk density, maximum density, and air void content, as well as performance tests such as indirect tensile strength (TSR) and wheel tracking, enabling a comprehensive assessment of the mechanical properties and durability of the analysed mixtures. • The effect of partial replacement of hydrated lime (HL) with calcium carbonate (CC) in asphalt mixtures was studied. • Mechanical tests were conducted to measure the resistance to cracking, stability, and durability against water and freeze-thaw cycles. • Asphalt mixtures with varying proportions of HL replacement by CC were designed and evaluated. • The HL-CC combination enhanced the indirect tensile strength (TSR). • The 25 % HL – 75 % CC mix showed the best rutting resistance, remaining well below the 12.5 mm limit.