Large-Size Macadam Mixture Stabilized with Industrial Solid Waste Fly Ash and Slag Powder: A New Mixture to Improve the Performance of Pavement Base Material

Several studies have highlighted that substituting cement with industrial solid waste materials, such as fly ash and slag powder, can enhance the crack resistance of cement-stabilized macadam bases. A mixture incorporating large particle size gravel exhibits an effective skeleton and support mechanism. To address the issue of cracking in conventional cement-stabilized macadam bases, this paper proposes a novel material: large-size macadam mixture stabilized with industrial solid waste fly ash and slag powder (LSM-SWFS mixture). This study proposes a ratio design method aimed at achieving a tightly packed particle arrangement that facilitates an interlocking, dense structure. By replacing cement with fly ash and slag powder as the cementitious components, the LSM-SWFS mixture was prepared using the vibration compaction method. A series of tests, including unconfined compressive strength, compression modulus of resilience, and flexural-tensile strength assessments showed that the unconfined compressive strength and compression modulus of resilience of the LSM-SWFS mixture were slightly lower than those of the conventional cement-stabilized macadam material. However, its 90 days flexural-tensile strength exhibited a significant increase of 24.9%. Additionally, the drying shrinkage rate of the solid waste mortar specimen over 28 days was only 48.6% of that observed in the cement mortar specimen. The enhancement in flexural-tensile strength alongside the reduction in the drying shrinkage rate underscores the efficiency of the LSM-SWFS mixture in mitigating cracking issues.