Experimental study of compressive strength, permeability and impact testing in geopolymer concrete based on Blast furnace slag

Cement production hasalways been associated with environmental challenges due to carbon dioxide emissions. On the other hand, cement production is an energy-intensive process and leads to the consumption of abundant fossil fuels. In order to solve this problem, the productionof geopolymer concrete is on the agenda. The researchers decided to reduce the negative effects of cement production and have superior properties than ordinary concrete. In the current study, slag-based geopolymer concrete was used with 0-2% polyolefin fibers and 0-8% nano-silica to improve its structure. After curing the specimens under dry conditions at a temperature of 60°C in an oven, they were subjected to compress strength, tensile strength and Drop weight hammertests to evaluate their mechanical properties, as well as Permeability test to assess their durability. tests were performed at 7 and 90 days of ageat ambient temperature (20°C). The addition of nano-silica enhanced the whole properties of the slag-based geopolymer concrete.Increasing the curing age improved the results of all tests. The results of all tests in geopolymer concrete showed the superiority of the results over conventional concrete. At the 28-day curing age, the addition of up to 8% nanosilica to the geopolymer concrete composition improved the compressive strength test results by 19.01%, water permeability by up to 35% and impact strength by up to 36.36%. Addition of up to 2% of polyolefin fibers in the composition of geopolymer concrete resulted in a 28.95% decrease in compressive strength but a 20% improvement in water permeability and an 8.26-fold increase in impact strength. In the following, by conducting the SEM test, a microstructure investigation was carried out on the concrete samples. In addition to their overlapping with each other, the results indicate the geopolymer concrete superiority over the regular concrete. Besides, it demonstrated the positive influence of nano-silica addition on the concert microstructure.