Effect of Strontium Aluminate Addition on the Mechanical and Surface Properties of Hardened Cement Pastes

Hardened cement pastes made of ordinary Portland cement (OPC) and strontium aluminate (Sr₄Al₁₄O₂₅)-Sol were made using a water cement ratio of 0.257 weight by weight. Two pastes containing (Sr₄Al₁₄O₂₅)-Sol with 1 and 3% content by the weight of OPC were prepared. All pastes were cured for various time intervals within the range of 1 to 28 days. X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), compressive strengths, and surface properties were studied and related as much as possible to the pore structure of the hardened pastes (1 and 3%). The addition of strontium aluminate to OPC results in an increase in the values of specific surface area and a decrease in values of average pore diameter of the hardened pastes (1 and 3%) as compared to the hardened neat cement pastes (OPC); this led to a higher value of compressive strengths of hardened cement pastes (Sr₄Al₁₄O₂₅)-Sol admixtire, especially at 1% addition.