This study, undertaken in 2003–2004, aimed to:
Samples of fresh, partly weathered and weathered rocks of three rock types were taken from four quarries. Cement, lime or Durabind was added to the partly weathered samples at two levels.
The untreated and treated samples were analysed. Proctor Needle and CBR testing was performed on the partly weathered samples.
Volcanic rocks contained a higher proportion of more readily weathered minerals than greywacke. Drury greywacke was more intensively sheared than Otaika greywacke. All partly weathered materials treated with 3% of additive had satisfactory CBR values. Methylene blue tests and X-ray diffraction analysis confirmed that 3% additive almost eliminated swelling tendencies.
Geochemical studies identified that additives reversed the trends of changing fluid composition caused by weathering.
Cement stability was investigated by suspending crushed treated samples in water. Swelling tendency increased over time, but in alkaline conditions, the aggregates returned to 30–70% of their original values after four days.