Nitrogen Adsorption Measurement for Pore Structure Characterisation of Cement–Oil Shale Ash Composite Exposed to an Aggressive Salt Environment

Despite cement remaining a dominant material in the construction industry, researchers are increasingly exploring strategies to reduce its consumption by incorporating supplementary cementitious materials or by developing alternative binder systems utilising various ashes produced by power plants during the combustion of different waste streams. In this context, the present study investigates the influence of two types of oil shale ash on the pore structure of C-S-H under aggressive environmental conditions. To address these issues, a comprehensive pore structure analysis was conducted using nitrogen gas physisorption, applying multiple analytical approaches including Dubinin-Radushkevich, Horvath-Kawazoe, quench solid density function theory, and Barett-Joyner-Halenda for pore volume and pore size distribution. Pore surface fractal dimension obtained by Neimark Kiselev and Frenkel-Halsey-Hill was compared. The results revealed that the deterioration of C-S-H structure depends on the ash type and the exposure duration to the sulfate-chloride solution.