The effect of coarse tire waste and nano silica on high temperature resistance of geopolymer concrete with blast furnace slag binder

In this study, geopolymer concrete (GB) samples of three different binder dosages (300 kg/m3, 400 kg/m3 and 500 kg/m3); the effects on mechanical and durability properties were investigated in binder contents consisting of 98% blast furnace slag (YFC) and 2% nano silica (NS). In the aggregate composition; while natural sand was used as fine aggregate, coarse rubber waste (ILA) was substituted in different proportions (0%, 5%, 10% and 15%) of coarse aggregate (4-8 mm). After the solid was obtained as described, activation of the GB samples was achieved using 12 M sodium hydroxide (NaOH) solution. The Solution/binder (Ç/B) ratio was kept constant at 0.45. The produced GB samples were left to cure at room temperature for 28 days. After the samples, which completed the curing period, were exposed to temperatures of 250ºC, 500ºC and 750ºC for 1 hour, their mechanical (compressive, bending, splitting tensile strength and impact strength), physical (weight change and capillary permeability) and microstructure properties were investigated. Experimental findings revealed that the increase in binder dosage resulted in significant increases in all mechanical properties and it was estimated that this was due to the formation of a denser and more compact microstructure than their counterparts produced using lower binder dosage. In addition to the negative effects of using ILA on compressive strength and high temperature resistance, other performance criteria such as flexural strength, impact strength and splitting tensile strength values of GB samples were significantly improved with the use of ILA. As a result, experimental findings showed that the use of coarse waste tire in GB production is advantageous in terms of some mechanical and durability properties. Keywords: Geopolymer, coarse waste tire, high temperature, blast furnace slag, nano silica, capillary permeability, impact resistance.