Experimental study of the effect of adding fibers and mineral processed materials on geopolymer concrete

Geopolymer concrete was proposed in order to eliminate the disadvantages (such as low strength and environmental damage) caused by the use of ordinary concrete in structures. In making this type of concrete, processed geopolymer materials from mineral sources such as slag and nanosilica replace cement and produce strong geopolymer concrete. In this laboratory research, a mixing design was made of control concrete containing Portland cement. Then geopolymer concrete was produced in three designs. The first design contains 100% of the slag of the composing furnace and the second and third designs contain 92% of the slag of the composing furnace and 8% of nanosilica, respectively, containing 1 and 2% of polyolefin fibers (4 mixing designs in total). Then, modulus of elasticity and tensile strength tests at 7 and 28 days of processing time at room temperature were performed on concrete samples. SEM test was performed on concrete samples at 90 days of age for validation with other results. The results indicate that increasing the curing age of concrete improved the results. In the modulus of elasticity and tensile strength test, the addition of fibers to geopolymer concrete at the age of 28 days, improved the results in Figure 19 (2% of fibers) compared to Figure 2 (no fibers) by 21.19 and 24.07%, respectively. Increasing the fibers improved the results of tensile strength tests and modulus of elasticity of geopolymer concrete compared to control concrete. The results of the SEM test overlapped with the results of other tests.