Use of natural pozzolana as alternative to Portland cement with recycled pebbles for manufacture of concrete with environmental properties

The construction industry is a major contributor to environmental degradation due to the widespread use of traditional building materials such as cement. Consequently, there is an urgent need to develop sustainable alternatives for producing green concrete using natural, non-manufactured materials. While cement plays a vital role in human habitat development, its extensive use significantly contributes to global warming by emitting carbon dioxide during the production of clinker, the primary binding material in cement. This research investigates the replacement of Portland cement with natural pozzolana at replacement ratios ranging from 10% to 50%. The study examines the impact of this substitution on the physical properties, particularly thermal conductivity, and mechanical properties, such as compressive strength. Recycled aggregates are used as a substitute for natural aggregates, contributing to sustainable development by conserving natural resources. The results indicate that as the percentage of cement replaced with pozzolana increases, the thermal resistance of concrete improves. Replacing cement with an equal mass of pozzolana leads to a 5% reduction in thermal conductivity. Additionally, recycled aggregates exhibit greater thermal resistance compared to natural aggregates. With a 50% replacement of cement with ground pozzolana, the thermal resistance increases by over 24%. It was also observed that the decrease in compressive strength of the resulting concrete remains acceptable if the replacement with pozzolana is less than 50%.