Abstract:
This research first examined the historical use of Pozzolana materials with lime since Roman times to improve the durability of structures. It then focused on studying mixtures of Portland cement (ordinary and sulfate-resistant) with natural Pozzolan available in Syria. Concrete samples were produced with varying percentages of cement replacement by Pozzolan (0%, 10%, 20%, 30%) and were cured in different environments (water as a reference, and a concentrated nitric acid environment to simulate pollution). The samples were then tested at different ages (up to 180 days) to measure changes in weight, flexural tensile strength, and compressive strength.Natural Pozzolan also plays a significant role in reducing the carbon footprint of cement manufacturing, which is one of the main strategies for a more sustainable cement industry.The main results showed that Adding Pozzolan delays the setting time and reduces the heat of hydration of concrete, which is beneficial for mass concrete structures. In the water environment, the long-term compressive strength (180 days) of samples containing Pozzolan improved, approaching that of the reference samples. In the acidic environment, samples containing Pozzolan (especially at 20%) exhibited higher corrosion resistance and a noticeable improvement in tensile and compressive strength compared to the reference samples, which deteriorated significantly. Overall, Pozzolan enhanced the durability of concrete in aggressive environments, with a 20% replacement ratio demonstrating balanced and good performance. The study established statistical relationships that can be used to predict the behavior of Pozzolana concrete and confirms the feasibility of using these local materials to improve the durability of concrete structures.