Use of Waste Slag and Rubber Particles to Make Mortar for Filling the Joints of Snow-Melting Concrete Pavement

Waste slag and rubber particles are commonly used to modify concrete, offering benefits such as reduced cement consumption and lower greenhouse gas emissions during cement production. In this study, these two environmentally friendly, sustainable waste materials were proposed for the preparation of mortar intended for snow-melting pavements. A series of experiments were conducted to evaluate the performance of the material and to determine whether its compressive and flexural strengths meet the requirements of pavement specifications. The mortar’s suitability for snow-melting pavements was assessed based on its thermal conductivity, impermeability, and freeze–thaw resistance. The results indicate that slag, when used in different volume fractions, can enhance the compressive and flexural strength of the mortar. Slag also provides excellent thermal conductivity, impermeability, and resistance to freeze–thaw cycles, contributing to the overall performance of snow-melting pavements. When the slag content was 20%, the performance was optimal, with the compressive strength and flexural strength reaching 58.5 MPa and 8.1 MPa, respectively. The strength loss rate under freeze–thaw cycles was 8.03%, the thermal conductivity reached 2.2895 W/(m * K), and the impermeability pressure value reached 0.5 MPa. Conversely, the addition of rubber particles was found to decrease the material’s mechanical and thermal properties. However, when used in small amounts, rubber particles improved the mortar’s impermeability and resistance to freeze–thaw cycles. When the rubber content was 5% by volume, the impermeability pressure value reached 0.5 MPa, which was 166.7% lower than that of ordinary cement mortar. Under freeze–thaw cycles, the strength loss rate of the test block with a rubber content of 25% volume fraction was 9.83% lower than that of ordinary cement mortar.