The Durability of Cement-Treated Clay-Granite Powder and Slag-Treated Clay-Granite Powder Composites Under Seawater Exposure

Granite powder, a waste product of quarried granite rocks, is known for increasing the strength of cement-treated clay composites due to its pozzolanic reactivity. However, the durability of the established composites under seawater is unknown and needs to be assessed. Therefore, we investigated the durability under seawater exposure of cement-treated clay and slag-treated clay composites containing 0% and 30% granite powder and 8% cement or 30% steel slag to the dry mass of clay. The composites were exposed to seawater in the laboratory at 30⁰C for 0, 28, and 63 days and tested their unconfined compressive strength (UCS) and chemical compositions using XRF. Consequently, after exposure, seawater samples were tested for their calcium and magnesium concentrations using a photometer. The UCS of cement-treated clay-granite powder and slag-treated clay-granite powder composites were higher than those of their respective control samples that did not contain granite powder for all the exposure days. The stress–strain curves show that the slag/cement-treated clay-stone power composites fail at higher stress and strain than their respective control samples. The cumulative Ca²⁺ elution was significantly higher in control samples than in the cement-treated clay-granite powder and slag-treated clay-granite powder composites. Conversely, the Mg²⁺ absorption was similar in the cement-treated clay-granite powder and slag-treated clay-granite powder composites and their respective control samples. The cement-treated clay-granite powder and slag-treated clay-granite powder composites were durable under seawater exposure and improved the UCS of cement-treated clay and slag-treated clay.