The possibility of fly ash and blast furnace slag disposal by using these environmental wastes as substitutes in portland cement

Abstract

The possibility of disposing of fly ash (FA) and blast furnace slag (BFS), which are environmental wastes, by using them as substitutes in portland cement was examined in this study. Portland cement (CEM I), FA, BFS, CEN standard sand, and water were used in the production of mortars. Blended cements were obtained by substituting FA, BFS, and a mixture of FA and BFS (FABFS) at 5.0%, 10.0%, 15.0%, and 20.0% ratios in portland cement. Physical (Blaine area, density, initial and final setting time, and fineness), mechanical (flexural strength and compressive strength), radiation permeability (determination of linear absorption coefficient) and high-temperature experiments were performed on the FA, BFS, and FABFS samples. Mortar prism samples with a size of 40 × 40 × 160 mm were obtained using these cements. The samples were exposed to five temperatures: 20, 150, 300, 700, and 900 °C. Mortar samples kept at 20 °C were used as references. A total of 390 samples were studied under air cooling (spontaneous cooling at 20 ± 2 °C in laboratory environment). After the mortar samples reached at room temperature, flexural strength and compressive strength tests were carried out on the 28th and 90th days. The test results showed that FA, BFS, and FABFS can be used as pozzolanic additives in cement mortars both alone and together and can be applied in buildings with a high risk of fire up to certain temperature values. The sample with the highest linear absorption coefficient was the FABFS sample, and as the sample with the lowest radiation permeability, it was determined to be appropriate for use in buildings that are exposed to radiation effects.