Investigation of the Pull-Off Strength of Geopolymer Concrete Containing GGBFS and Natural Zeolite Powder

In this paper, effects of curing methods (i.e. curing at ambient temperature (A), in oven (O) and in boiling water (BW)), NaOH solution concentration (i.e. 8 and 12 moles/liter) and disc thickness (i.e. 1, 2 and 3 cm) on pull-off strength (POS) of the geopolymer concrete containing Ground Granulated Blast Furnace Slag (GGBFS) and Natural Zeolite Powder (NZP) have been investigated. The results show that the value of the POS obtained from the 3 cm thickness disc is on average 2.6% higher than that obtained from the 2 cm thickness disc. This implies that the discs with thicknesses of 2 and 3 cm have given approximately equal values of the POSs. Moreover, the value of the POS obtained from the 2 cm thickness disc is on average 28.4% higher than that obtained from the 1 cm thickness one. Based on the results obtained from the 2 cm thickness disc: a) the ratios of the POSs of the samples cured in boiling water and oven to that of the specimen cured at ambient temperature have been obtained on average equal to 1.383 and 1.089, respectively. b) as 20% wt. of the GGBFS is substituted by the NZP, the value of the POS reduces by an average of 16.29%. c) as the NaOH solution concentration increases from 8 to 12 mole/liter, the value of the POS increases by an average of 14.48%. From the results, there is a strong nonlinear relationship between the compressive and pull-off strengths of the geopolymer concrete.