Artificial fly ash based aggregates properties influence on lightweight concrete performances

The effect of the application of pelletized fly ash based aggregates obtained through different processing techniques on the behavior of lightweight concretes was analyzed. Experimental program implied production of four lightweight artificial aggregates—cold bonded and sintered pellets based on either mechanically activated or non-activated low-calcium fly ash and water glass. The lightweight concrete behavior was compared to that of normal-weight concrete through compressive strength, flexural strength, porosity, shrinkage, and modulus of elasticity investigation. Differences in concretes characteristics were discussed with SEM imagining support. The statistical analysis of lightweight aggregate and ash properties contribution on concrete performances was realized by analysis variance model (ANOVA). Optimal production combination that maximizes lightweight concrete performance was determined by employing response surface methodology. An increase in concrete strength induced by the increase in ash fineness was noticed. Mechanical activation also had effect on the pellets sintering period and sintering temperature reduction. The 28- and 56-day lightweight concrete specimens exhibited properties that met the requirements for normal-weight concretes. Finally, the ideal combinations of ash pellets production parameters and properties that gave the lightweight concrete with behavior matching to that of standard concrete were established. The production capability of lightweight concrete with advanced performances based on artificial aggregate approves the principle of waste material reusing and enables cleaner and economically sustainable concrete manufacturing procedure.