Performance investigation of a low carbon cold-bonded lightweight aggregate utilizing recycled yellow river silts

The resource depletion and environmental pollution caused by the excessive exploitation of non-renewable natural aggregates have become significant challenges restricting social development. To reduce the exploitation of natural aggregates and promote the large-scale resource utilization of Yellow River silt, a low-carbon cold-bonded lightweight aggregate manufacturing new technology was proposed in this study. To investigate the feasibility of Yellow River Silt Lightweight Aggregate (YRSLA) in road construction, its granulation efficiency, physical properties, single-particle compressive strength, and durability under dry-wet and freeze-thaw cycles were tested. Meanwhile, the YRSLA internal structure and the distribution of hydration products were analyzed by using XRD and SEM. The results demonstrated that the incorporation of 10% clay into the Yellow River silt significantly enhanced the performance of the YRSLA. Its granulation efficiency and single-particle compressive strength increased by 15% and 34%, respectively, whereas dry-wet and freeze-thaw mass losses decreased by 12.1% and 21.9%. This improvement stems from a dual hydration mechanism, where clay-cement synergy fostered a denser gelling matrix, promoted C-S-H gel formation, and improved structural porosity. The optimal YRSLA formulation (74% silt, 15% cement, 10% clay, 1% lime) achieved a bulk density of 1154 kg/m³and a compressive strength of 3.34 MPa, demonstrating suitability as roadbed filler due to its balanced durability and moderate strength. However, its porous structure and high-water absorption limited its application in pavement surface layers where natural aggregates remain irreplaceable.