Part of the results of an ongoing laboratory work carried out to design a structural lightweight high strength concrete ( SLWHSC ) made with and without mineral admixtures is presented. Basaltic-pumice ( scoria ) was used as lightweight aggregate.
A control lightweight concrete mixture made with lightweight basaltic-pumice (scoria) containing normal Portland cement as the binder was prepared. The control lightweight concrete mixture was modified by replacing 20% of the cement with fly ash and by replacing 10% of the cement with silica fume. A ternary lightweight concrete mixture was also prepared modifying the control lightweight concrete by replacing 20% of cement with fly ash and 10% of cement with silica fume. Two normal weight concretes (NWC) were also prepared for comparison purpose.
Fly ash and silica fume are used for economical and environmental concerns. Cylinder specimens were cast from the fresh mixtures to measure compressive and flexural tensile strength. The concrete samples were cured at 65% relative humidity with 20 °C temperature. The density and slump workability of fresh concrete mixtures were also measured.
Laboratory test results showed that structural lightweight concrete (SLWC) can be produced by the use of scoria. However, the use of mineral additives seems to be mandatory for production of SLWHSC. The use of ternary mixture was recommended due to its satisfactory strength development and environmental friendliness. 17 refs.