Valorization of Quarry Sludge Waste as a Complete Fine‐to‐Coarse Lightweight Aggregate System for Structural Concrete

ABSTRACT

The accumulation of quarry sludge and the continuing demand for natural aggregates represent interconnected environmental management challenges in rapidly urbanizing regions. This study investigated the valorization of fine‐grained quarry sludge wastes from two regions of Istanbul, designated GM and CA, as a complete aggregate source for structural lightweight concrete. The wastes were characterized by XRF, XRD, and laser diffraction, pelletized using only water, and thermally treated by expansion at 1150°C or sintering at 1120°C. Crushing‐strength screening led to the exclusion of particles larger than 8 mm and the development of a 0–8 mm aggregate system combining sintered coarse particles with crushed and classified finer fractions. This system enabled the complete replacement of both natural fine and coarse aggregates. The resulting GM and CA concretes exhibited water absorption values of 8.0 ± 0.1% and 11.2 ± 0.1%, respectively. Their 28‐day bulk densities were 1756 ± 5 and 1704 ± 21 kg/m ³ , while compressive strengths reached 31.35 ± 3.47 and 26.49 ± 1.41 MPa. Fourteen‐day ASTM C1260 expansion remained below 0.03% for both aggregate systems. SEM‐EDX observations further revealed dense interfacial transition zones with partial cement‐paste penetration into surface‐accessible aggregate pores. These findings demonstrate a technically viable pathway for managing quarry sludge as a complete fine‐to‐coarse aggregate resource, supporting waste diversion and reduced dependence on virgin aggregates without chemical additives during pelletization.