چكيده به لاتين
The production of Portland cement, which is the raw material for concrete production, accounts for about 5 to 7% of the total global carbon dioxide emissions. Also, cement production consumes non-renewable resources such as limestone and leads to ecological imbalance. Geopolymers are a group of cement replacement materials that gain resistance through the alumino-silica reaction. Alumino-silica materials are the waste of industries such as power plants and steel production industry, and their consumption, in addition to reducing the demand for cement, leads to the reuse of part of the waste materials of the relevant industries in the construction industry. As a new material, geopolymer concrete has shown the capacity to replace conventional concrete. This concrete sample, while maintaining the same properties as concrete, when properly designed and produced with additional cement materials, has the capacity to reduce the carbon dioxide footprint caused by cement production by 80%. Therefore, many researchers have named geopolymer concrete as the concrete of the future. In the current research, the effect of increasing the concentration of alkaline activator, as well as the effect of adding graphene oxide nanosheets in improving the mechanical properties of geopolymer concrete (based on blast furnace slag) and increasing its durability against destructive factors have been evaluated. For this purpose, geopolymer concrete was activated by sodium hydroxide solution with concentrations of 3, 6 and 12 mol/liter. The results showed that by increasing the concentration of alkaline activator, the mechanical properties of geopolymer concrete increase significantly. Also, geopolymer samples containing 0.03 and 0.05 percent graphene oxide along with control samples were subjected to tests such as: slump, compressive strength, tensile strength, volume water absorption, electrical resistance and ultrasound test. The results indicated that by adding graphene oxide to slag-based geopolymer concrete and increasing its concentration to 0.05 percent by weight of the adhesive, as well as using slag wool fibers in geopolymer, despite the loss of efficiency, the mechanical properties of concrete including compressive strength and the tensile strength increases by 35 and 51% at the age of 7 days, by 40 and 55% at the age of 28 days, and by 43 and 57% at the age of 90 days. Improving the characteristics related to durability is also one of the effects of adding graphene oxide to geopolymer concrete; Because it significantly reduces the water absorption percentage of concrete. The reduction of the electrical resistance of concrete in the presence of graphene oxide was also a controversial point of the current research, which was somewhat improved with the passage of curing time, the consumption of alkaline activators in the geopolymerization reaction, and the subsequent reduction in the amount of conductive ions in the geopolymer matrix.
