The Effect of Using Alkaline Adhesives on the Durability of Lightweight Structural Concrete against Harmful Environments

The use of lightweight stone materials and alkaline adhesives to replace gravel and ordinary Portland cement in concrete production prevents the emission of a significant portion of greenhouse gases, saves energy, and reduces the dead load of the structure. In this study, porous coarse-grained lava rock has been used to reduce the density of concrete, as well as slag and fly ash, as alternative materials to ordinary Portland cement in concrete production. Alkaline activation of the pozzolans was performed by solutions of 14 M sodium hydroxide and sodium silicate with a mass ratio of 1: 2. Chloride ion invasion, sulfate invasion, and the combination of sulfate and chloride invasion are on the research laboratory agenda. Concrete with alkaline slag and different ratios of slag and fly ash for alkaline activation and hydrated Portland cement have also been selected for comparison. According to the obtained results, Portland cement concrete tolerated the fastest deterioration against combined aggression with a reduction of almost 10% in compressive strength, the highest compressive strength was 55 MPa slag concrete, and with increasing fly ash replacement, the short-term mechanical properties are weakened, but with decreasing water absorption loss, on average, by about 12%, the long-term durability and protection of reinforced concrete increases.