Effect of sodium Hydroxide solution concentration and sodium silicate to sodium hydroxide ratio on the compressive strength and water absorption of slag based alkali-activated concrete

Alkali-activated cement is a new and innovative material in the construction industry and with desirable performance that by use of natural Pozzolans and industrial waste containing aluminosilicate can be used as an eco-friendly substitute material for Portland cement. On the other hand mechanical and durability properties of concrete has made it important to research on the factors influence on these two characteristics. In this paper it’s tried to study and manufacturing high perfomence concrete based on ground blast furnace slag by using sodium base alkaline solution. Three concentrations 18.75,15 and 11.25 and three ratios of Na2SiO3 to NaOH have been used. The ratio of water to the binder material is considered constant in all mix designs. In this study, for curing samples were submerged in water at ambient temperature samples. Compressive test results show that by decreasing the NaOH concentration to 11.25 mechanical strength of this material decreases and while by decreasing this parameter from 18.75 to 15 this parameter almost stay constent. Water absorption test was done on samples at 28 days age. This test shows that increasing of NaOH concentration reduces water absorption of samples