The suitability for using glass and fly ash in Portland cement concrete

The utilization of glass and fly ash as additives in concrete introduces many benefits from technical and environmental points of view. Change in the compressive strength of concrete depends on the aggregate-cement interactions and interface bonding mechanism. It is well known that silica in the glass can be highly reactive with the alkalis in cement paste. As a result of pozzolonic reaction, fly ash fills in the pores in the material. Therefore, using fly ash and glass as additives in concrete can improve the mechanical properties of concrete. In this study, fly ash, glass and fly ash-glass were used as additives to make concrete specimens. Fly ash additive percentages by weight relative to cement were 0%, 10%, 20% and 30%. Glass additive percentages by weight relative to cement were 0%, 5%, 10% and 15%. Fly ash-glass additive percentages by weight relative to cement were, 10% fly ash+15% glass, 20% fly ash+15% glass and 30% fly ash+15% glass. The water/cement ratio was 0.45 and the cement used was Portland cement. After the specimens were cured for 7 and 28 days, the compressive strength, indirect tensile stress, permeability and freeze/thaw durability were measured. The purpose of this study is to investigate the suitability for using glass, fly ash and fly ash-glass in Portland cement concrete. The test results showed that concrete with 15% glass and 30% fly ash substitution gave the best results with respect to compressive strength, indirect tensile stress and the coefficient of capillary permeability. As a result, It is observed that compressive strength, permeability and durability of concrete are improved by adding glass and fly ash.