EFFECT OF CaO CONTENT ON GGBS BASED GEOPOLYMER CONCRETE

Abstract

GGBS based Geopolymer concrete is innovative composite material for civil engineering industry for which binding material cement and water is replaced bypozzolanic material like fly ash, GGBS and activated by highly alkaline solutions to act as a binder in the concrete. Mix design procedure used is proposed on the basis of quantity, fineness of fly ash, quantity of water, grading of fine aggregate, fine to total aggregate ratio and GGBS is used for M40 grade of GGBS based Geopolymer concrete. During experimental work, variation of different parameter like ratio of alkaline solution ratio (Na2SiO3/NaOH) of 2 was taken. Different molarities such as 12M and 16M of NaOH was taken. In addition, different percentage of such as 0%, 20%, 40%, 50% of GGBS with solution to fly ash ratio 0.38 and sodium silicate to sodium hydroxide ratio 2 was taken. The samples are cured in oven at 450C temperature for 24 hrs. The results show that the strength of geopolymer concrete increases with increase in percentage of GGBS in the mix. The strength increase up to 40% replacement of fly ash with GGBS after that it starts decreasing. In case of fly ash based geopolymer concrete as there is no CaO content so curing takes place due to polymerization process, but with the addition of GGBS in fly ash based geopolymer concrete curing is due to combine effect of polymerization as well as heat of hydration due to presence of alkaline solution and CaO respectively. As molarity of NaOH increases from 12M to 16M, compressive strength, flexural strength, split tensile strength also increases.