Strength properties of fibre and hybrid fibre reinforced geopolymer concrete made with low calcium flyash

This paper presents an experimental study on the strength properties of plain geopolymer concrete, fibre reinforced geopolymer concrete and hybrid fibre reinforced geopolymer concrete made with low calcium flyash. The strength parameters considered in this study are compressive strength, split tensile strength and flexural strength. The polypropylene fibre incorporation in 8M alkali activated geopolymer was performed by 0.5, 1, 1.5 and 2% of total volume of concrete. A maximum of 4.41%, 7.57% and 20.12% increase in compressive strength, split tensile strength and flexural strength, respectively were noticed corresponding to the addition of 2% PP fibre in GPC. The optimum was taken as 1% since the specimen had already attained a compressive strength more than the target strength and further increasing the fibre content won’t be advisable considering the various limitation of excess fibres in concrete. Keeping the optimum dosage of polypropylene fibre as constant, glass fibres are added to the concrete in different proportions of this optimum dosage viz. 5%, 10%, 20%, 30% and 40% of 1% of PP fibre and the effect of these hybrids in compression, tension and flexural strength is experimentally investigated. Based on the test results, it was observed that a maximum of 11.38 %, 7.87 % and 10.67 % increase in compressive strength, split tensile strength and flexural strength respectively by 10% replacement of optimum PP fibre with glass fibre with respect to the geopolymer concrete without fibres.