Durability and Performance Evaluation of Lightweight Self-Compacting Concrete Using Artificial and Natural Lightweight Aggregates in Sulfuric Acid Environment: An Experimental and Analytical Study

Efforts to reduce the weight of concrete have led to extensive research on lightweight concrete. Reducing concrete weight can decrease the overall structure weight, thereby reducing the applied forces. This study investigates the effects of two lightweight aggregates, Leca and Scoria, on the properties of self-compacting concrete in both fresh and hardened phases, as well as its durability in sulfuric acid environments. Fresh concrete tests included slump flow, T50 slump, L-box, U-box, J-ring, and specific weight, while hardened samples were evaluated for compressive strength in both normal and acidic conditions, along with weight loss in acidic environments. Results indicated that three key factors influencing concrete performance are specific weight, appearance, and water absorption percentage of the aggregates. Scoria lightweight concrete demonstrated approximately 60% greater strength compared to Leca when using equal volumes of both aggregates. In acidic environments, the most significant reduction in compressive strength for Leca occurred between 1 and 7 days, approximately 27%, while for Scoria, this reduction was observed between 7 and 28 days at about 25%. This highlights that the acidic environment has a greater impact on the strength reduction of Leca in the early days and on Scoria in the later stages. Furthermore, the highest weight loss for both concrete types in acidic conditions was noted between 1 and 14 days, reaching approximately 93%, while only a 7% weight reduction occurred between 14 and 28 days. Notably, compared to their initial weight, the samples exhibited a minimal weight loss of about 1% to 2%.