experimental study of properties of green concrete based on geopolymer materials under high temperature

Geopolymer concrete (gpc) are known as green and nature-friendly concretes. in the current research, gpc based on granulated blast furnace slag (gbfs) was used with 0-2% polyolefin fibers (pofs) and 0-8% nano silica (ns) to improve its structure. after curing the specimens under dry conditions at a temperature of 60 °c in an oven, then subjected to permeability test, water absorption test and uultrasonic pulse velocity (upv) test at the ages of 7, 28 and 90 days. on the other hand, ns reduced the amount of water absorption and water permeability in concrete by 24 and 44%, this is due to the property of filling the pores with ns. moreover, by conducting the ultrasonic, x-ray fluorescence (xrf), x-ray diffraction (xrd), and scanning electron microscope (sem) tests, a microstructure investigation was carried out on the concrete samples. in addition to their overlapping with each other, the results indicate the gpc superiority over the regular concrete. besides, it demonstrated the positive influence of ns addition on the upv and microstructural properties concretes against the heating treatment at the age of 90 days. heat caused a drop in the results by destroying the concrete microstructure.