Evaluate Effect Of Temperature On mechanical properties of Geopolymer Concretes blast furnace slag by using nanosilica and polyolefin fiber

Abstract

Cement production has always 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 production of geopolymer concrete is on the agenda. The researchers decided to reduce the negative effects of cement production and have superior properties than ordinary concrete . Geopolymer cement matrix, due to the production of abundant hydrated gels, has a higher density and cohesion than the Portland cement matrix, and this is the main reason for increasing the resistance of this type of concrete to high heat compared to ordinary concrete. In this study, the effect of heat on the mechanical properties of slag geopolymer concrete containing 0 to 8% nanosilica and 1 to 2% polyolefin fibers at 90 days of processing age was investigated and XRF, XRD and SEM experiments were used to study the microstructure. In the optimal design of slag geopolymer concrete (containing 8% nanosilica and free of fibers), we saw a decrease of 8 and 44% in the values after and before heating in compressive strength tests and determination of ultrasonic pulse speed of concrete, while in control concrete, the results decreased Reached 38 and 37 percent. In slag geopolymer concrete containing 8% nanosilica and 2% fibers, tensile strength and modulus of elasticity equal to 14 and 34% showed results after and before heating, for control concrete these figures decreased by 51 and 59% in the results. Received, the results of the falling hammer impact test also had a reduction in the resistance of heat-exposed concrete to hammer blows. In the end, the microstructural studies were in overlap and in coordination with the results of the tests of this study.