Abstract
The resistance of alkali-activated materials (AAMs) to degradation processes, particularly the decalcification, was studied in this paper. The ground granulated blast furnace slag was alkali-activated using various activators with the same activator dosage 6% Na2O by slag weight (sodium hydroxide, sodium waterglass and sodium carbonate) and subjected to testing of decalcification resistance (immersion in 6M NH4 NO3) for 84 days. The reference samples were stored in water. The progress of degradation was studied using the phenolphthalein technique, mechanical properties testing (compressive and flexural strength), and dilatometry analysis or weight measurements. The results obtained were compared to the CEM III/A 32.5R. The significant loss of mass along with the deterioration of mechanical properties were observed for all binder types, still some of the AAMs showed better durability than the cementitious one.
Highlights
The production of Ordinary Portland Cement (OPC) increases every year due to the needs of the building industry
Residual flexural strength compared to water storage about 82.5; 69.6; 54.6 and 21.6% was observed in the following alkaline activator order NaWG; NaOH; Na2CO3 and ending with the cementitious system after 84 days of deposition to ammonium nitrate solution
This paper investigated the effect of alkaline activator type used for the alkali activation of blast furnace slag on the decalcification resistance
Summary
The production of Ordinary Portland Cement (OPC) increases every year due to the needs of the building industry. The alkali-activated blast furnace slag (AABFS) shows better resistance against the decalcification processes than the Ordinary Portland Cement, as stated in studies like [6,7,8,9] because of several aspects. The A-S-H can form a relatively stable passivation layer Another benefit arises from the absence of portlandite in AABFS, since it represents a potential “first” target for decalcification. The experimental study of decalcification resistance can be realized using the accelerated test – immersion in a solution of 6M NH4NO3 [10] The benefit of this method contrary to other acidic leaching is that there are no changes in silicon concentration. A comparative study of CEM III/A-32.5R was carried out too
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