Gravel wash mud, a quarry waste material as supplementary cementitious material (SCM)

The suitability of gravel wash mud (GWM), a sludge waste from gravel quarrying, is examined for its use as a partial
Ordinary Portland cement (OPC) clinker substitute. The gravel wash mud was dried, milled into a fine powder and
calcined at 750°C, 850°C and 950°C. In this study, various characterisation methods including particle size distribution
(PSD), X-ray fluorescence (XRF), X-ray diffraction (XRD) and the simultaneous thermal analysis (STA) were applied
on the calcined GWM powders to determine the optimal calcination temperature. Over 200 specimens were prepared
based on different cement paste and mortar mixes to investigate the potential of calcined GWM powders as SCMs.
The pozzolanic activity of the GWM powders was verified by applying strength-based evaluation methods,
simultaneous thermal analysis and SEM on hardened samples. Very promising strength-enhancing capacities were
observed for samples containing GWM powders calcined at 850°C with a OPC replacement level of 20 wt.%.