Durability Properties of Geopolymer Concrete from Fly Ash and GGBS: Fid-Bau Portal

Durability Properties of Geopolymer Concrete from Fly Ash and GGBS

Srividya, T. / Kannan Rajkumar, P. R.

Geopolymer, a subclass of alkali activated binders can be synthesized from any silica and alumina rich secondary sources like fly ash (FA), ground granulated blast furnace slag (GGBS). The service life of structural members depends on the durability property of the concrete. Only durable concrete can protect the reinforcement from corrosion, thereby avoiding scaling of concrete from environmental exposure. This research aims to evaluate the durability of geopolymer concrete (GPC) manufactured using class F FA and GGBS activated using a mixture of sodium hydroxide (NaOH) and sodium silicate (Na₂SiO₃) solution. Two mixes of geopolymer concrete with blend ratio of FA and GGBS 4:1 (GPC 1), and 1:1 (GPC 2) was cast to study the strength, resistance to acid and sulphate attack, resistance to chloride penetration and depth of water penetration. To study the resistance to chemicals, the specimens were immersed in the solution with 5% sulphuric acid (acid attack test) and 5% sodium sulphate (sulphate attack test) for 28 days after curing. Resistance to chemical attack was evaluated from the weight and compressive strength (CS) changes. All the GPC mixes performed well on exposure to acidic and alkaline condition, and the results were compared to the GPC specimens before exposure. As per ASTM 1202-97, moderate exposure was observed in the case of the rapid chloride penetration test. Water penetration test shows moderate permeability of depth ranging from 5 to 20 mm. In addition to achieving better mechanical properties, GPC mixes performed well in all durability properties, thereby it can effectively replace the ordinary Portland cement (OPC)-based concrete in construction industries.