Use of Sulphoaluminate Cement in Grouted Macadam as Sustainable Pavement Material

Rutting of asphalt pavement is a major issue that affects its serviceability in a hot climate. Grouted macadam (GM) has been used as an alternative material to tackle rutting problems, thanks to its high stiffness. Yet, GM possesses some advantageous properties of asphalt pavements attributed to the contained asphalt binders. Although ordinary Portland cement (OPC) can be used as the grouting material for GM, GM using OPC needs a long period of time to develop its full strength even if admixtures are added for early strength development. Consequently, premature damage can occur if roads surfaced with GM are open to traffic shortly after construction. To address this challenge, a grouting material mainly based on sulphoaluminate cement (SAC) was formulated in this study, and an optimal combination of the grouting material and porous asphalt skeleton was developed. Test results indicate that GM based on SAC (named GM-SAC) can gain its compressive strength much more rapidly than the traditional GM materials. Results from an indirect tensile stiffness modulus test (ITSM) indicate that the GM-SAC also has good flexibility. An indirect tensile fatigue test (ITFT), a Hamburg wheel tracking test, and a thermal stress restrained specimen test (TSRST) have been conducted to characterize the performance of GM-SAC. Results indicate that GM-SAC exhibits outstanding fatigue and rutting resistance, but the low-temperature performance is worse than traditional hot-mix asphalt mixtures. Therefore, GM-SAC has strong potential to serve as a rutting-resistant surface material for pavements in hot climates.