Quarry waste clays as supplementary cementitious materials: Mineralogical evolution and pozzolanic performance after thermal activation
APPLIED CLAY SCIENCE, vol.281, 2026 (SCI-Expanded, Scopus)
- Publication Type: Article / Article
- Volume: 281
- Publication Date: 2026
- Doi Number: 10.1016/j.clay.2025.108085
- Journal Name: APPLIED CLAY SCIENCE
- Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Chemical Abstracts Core, Compendex, Geobase, Index Islamicus, INSPEC, Academic Search Ultimate (EBSCO), Engineering Source (EBSCO)
- Istanbul University Affiliated: No
Abstract
This study investigates the potential of thermally activated quarry waste as alternative supplementary cementitious materials (SCMs) for sustainable binder systems. Three clay-rich materials were collected from a sand quarry located on the European side of Istanbul: two natural overburden clays (Yellow Layer-YL and Blue Layer-BL) and one process-derived sludge waste (TA) generated during sand washing. All samples were sieved (<150 mu m), dried, and calcined at 800 degrees C for 2 h. Mineralogical (XRD), chemical (XRF), and thermal (TG, FTIR) analyses were conducted to evaluate phase transformation and amorphous phase development. Pozzolanic reactivity was assessed by the R-3 test, including heat release and bound water measurements. Results showed that the TA sample exhibited the highest reactivity due to its kaolinite content and fine, homogeneous particle structure. In contrast, the BL sample demonstrated limited reactivity owing to the dominance of thermally stable phases such as muscovite and albite. Mortar specimens prepared with 20 % SCM replacement were tested for compressive strength at 7, 14, and 28 days using both CEM I and CEM II binders. The TA-C mixture achieved a compressive strength index (CSI) of 102.9 % with CEM I at 14 days, indicating strong early-age performance, while YL-C showed the highest 28-day strength with CEM II (CSI = 97.9 %). These findings confirm that sludge-based SCMs, when properly activated, can match or even exceed the performance of conventional systems, offering a viable strategy for resource-efficient and low-carbon cementitious materials.