Effect of Coarse Aggregate Treatment On Characteristics of Pumice and Scoria Lightweight Concretes

Abstract

This study presents an experimental investigation of lightweight concretes production using typical pumice andscoria from Kelud volcano, Indonesia as coarse aggregates. Three different treatments were evaluated to obtain an effective treatment method. Method A was a combination of preheating to the temperature of 100oC and soaking for 2 hours. Method B was a direct presoaking for 3 hours and Method C was a premixing with water in the concrete mixer for 10 minutes. These methods were based on the water content of lightweight coarse aggregates tested before. The results showedthat Method A provided the highest water content compared to Methods B and C. Similarly, it also provided the most satisfying workability during concrete production. Moreover, all physical and mechanical characteristics of hardened concrete were not affected by the coarse aggregate treatment methods given. Therefore, Method A was considered an effective treatment method. Pumice and scoria lightweight concretes constituted the structural lightweight concrete withequilibrium densities in the range of 1724 kg/m3to 1837 kg/m3. The density reduction wasbetween21% and 24% sothat they can reduce the self-weight of structural element. However, the chord modulus of elasticity, the splitting tensile strength as well as the modulus of rupture was lower than the normal concrete and must be considered throughout in the structural lightweight concrete design.