Effect of natural pozzolana, pozzolanic sand, and basalt on thermal and mechanical properties of green concrete

Green concrete, also known as sustainable concrete, is a building material that aims to reduce environmental impact by using natural, recycled, or sustainable materials in its production. One way to achieve sustainability in concrete is to replace cement with pozzolanic materials, which not only reduces the carbon footprint but also improves the performance of concrete and reduces its cost. This study aims to use natural materials that can partially or completely replace cement and conventional aggregates in concrete mixes. pozzolanic gravel (GPoz) replaced coarse aggregate, basaltic sand (SBas) and pozzolanic (SPoz) replaced fine aggregate, while ground pozzolana (PN) replaced cement. This work focuses on the experimentation and simulation of concrete mixes using the four abovementioned materials. 36 cubes were cast to conduct the thermal conductivity test by direct exposure of concrete samples, where an insulated thermal chamber was designed from thermal bricks, equipped with a heat source from the bottom and an empty space for the tested sample from the top, and then the resistance test on simple pressure was conducted for the cubic samples at the age of 28 days. Pozzolanic aggregate, when used in combination with basalt sand, showed greater thermal resistance compared to conventional concrete. Even with the replacement of 50% of the cement with ground pozzolana, we notice an increase in resistance of more than 11%, but with the replacement of basalt sand with pozzolana sand, we notice an increase in thermal resistance of more than 53%. As for the mechanical properties represented by resistance on simple pressure, we notice an acceptable decrease in resistance when replacing cement with pozzolana, with the exception of mixtures containing aggregates and pozzolana sand together, where replacing 50% of the cement with pozzolana increases the resistance on simple pressure by more than 46.4%.