Effect of Sealed Curing on Perforated and Non-perforated Cenospheres-Based Lightweight Cementitious Composites

Fly ash cenospheres (FAC) are a by-product of thermal power plant coal combustion products. It is lightweight, hollow spheres composed primarily of silica and alumina, with a trace of other elements. FAC can help with sustainability in a variety of ways, such as conservation of resources, light-weight materials for construction, waste reduction, increased product performance, and lower carbon emissions. As a result, in order to fully benefit from FAC, it is required to investigate an ecological approach. The FAC’s shells are porous by nature and are sealed by a thin layer of glazed-crystalline film. By chemically removing this coating, the small openings on the outer covering can be disclosed, perforating the FAC and allowing pathways for water to propagate into the inner cavity of FAC. The use of FAC as an internal curing ingredient for partially substituting cement in cement mortar has been investigated in this study. Two types of cement mortar specimens with the same dimensions, 50 mm × 50 mm × 50 mm, were cast by using perforated fly ash cenospheres (PFAC) and FAC as cement replacement up to 25% by the weight of cement. Both types of FAC specimens were cured under sealed curing. The specimens were tested for reduction in density, ultrasonic pulse velocity, and compressive strength.