MECHANICAL STRENGTH DEGRADATION OF SLAG AND FLY ASH BASED GEOPOLYMER SPECIMENS EXPOSED TO SULFURIC ACID ATTACK

In this study, mechanical properties and durability performances of fly ash based geopolymer concrete (FAGPC) and slag based geopolymer concrete (SGPC) were investigated against 5% sulfuric acid attack. The low calcium (F-type) fly ash (FA) and ground granulated blast furnace slag (GGBS) were utilized as binder materials with an amount of 360 kg/m3, and a combination of sodium silicate and 14 M sodium hydroxide with a silicate to hydroxide ratio of 2.5 were used as an alkaline activator in order to produce geopolymer concretes. The binder amounts were selected in accordance with the XA3 chemical environmental condition given in TS EN 206 standard. An ordinary Portland cement concrete (OPC) was also produced and exposed to sulfuric acid attacks for comparison. The effect of sulfuric acid on 150x150x150 mm cube and 100x200 mm cylinder specimens was evaluated by visual inspection, weight change, compressive and splitting tensile strength tests. Results indicated that similar surface deterioration was observed on the cube and cylinder specimens due to acid exposure. However, cube specimens showed more weight loss than the cylinder specimens, which can be attributed to the higher acid influenced area due to the size effect. In addition, the SGPC specimens exhibited superior mechanical performance, while FAGPC specimens showed the poorest mechanical performance when low binder amounts (360 kg/m3) were utilized under sulfuric acid attack. The results also pointed out that slag based geopolymer concrete can be utilized in structural applications instead of ordinary Portland cement concrete.

Keywords:

Fly ash based geopolymer concrete (FAGPC), slag based geopolymer concrete (SGPC), sulfuric acid attack durability, mechanical performance,

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