Experimental Investigation on Exposure of Geopolymer concrete to High Temperature

Abstract

Now a days there is momentum in research of alternative binding material in concrete other than cement, which has lead this era towards development of geopolymer concrete. Various source materials can be used as binder materials like y ash, GGBS, rice husk ash, metakaoline, etc. Studies have confirmed that geopolymer concrete has good compressive strength, split tensile strength, exural strength and very good durability. There are many occasions where concrete can be exposed to elevated temperature like furnace, nuclear reactor, thermal processors, fire in any structure, etc. In such cases, it is necessary to understand the behaviour of concrete. There are many research reports available about behaviour of OPC concrete exposed to elevated temperature, but very few information is available on behaviour of geopoly- mer concrete exposed to elevated temperature. A preliminary study was carried out by varying three parameters for establishing mix design of rice husk ash blended y ash based geopolymer concrete(GCR). Those three parameters were alkaline solution to cementitious material ratio (0.3, 0.35, 0.4), molarity of sodium hydroxide solution (10M, 12M, 14M) and sodium silicate to sodium hydroxide solution ratio (1.5, 2, 2.5). Trial mix having maximum compressive strength was taken as final mix design of GCR for further studies. Standard size concrete specimens were casted for four different geopolymer mixes hav- ing variation in source material namely y ash based geopolymer concrete(GCF), y ash and GGBS based geopolymer concrete(GCFS), GGBS based geopolymer concrete(GCS) and Rice husk ash blended y ash based geopolymer concrete(GCR). These specimens were exposed to 500C, 700C and 900C for 1 hr. After exposure they were tested for evaluating mechanical properties like compressive strength, exural strength, split ten- sile strength, modulus of elasticity and bond strength. These properties of geopolymer concrete were compared with ordinary cement concrete(OC).