Prestressed Geopolymer Concrete

Abstract

Sustainable concrete is encouraged tremendously due to increasing rate of pollution in the world. One of the ways of producing sustainable and environment friendly concrete is geopolymer concrete. The geopolymer concrete replaces cement with other industrial waste as source material, and therefore is less harmful to environment and is environment friendly. In present study focuses on evaluation of geopolymer concrete beams under flexure behaviour and its comparison with ordinary Portland cement concrete beams. Effect of application of prestressing force on both geopolymer concrete beams and ordinary Portland cement concrete beams was also evaluated. M40 grade of concrete was decided as prestressing requires high strength concrete. Mixture design for M40 ordinary Portland cement concrete (OPCC) was carried out while certain modification was done in previous batch mixture design to obtain geopolymer concrete (GPC) of M40 grade. GPC was prepared by using various materials like Fly ash, GGBS, sodium hydroxide flakes, sodium silicate. Total 16 beam specimens were cast and tested using loading frame by applying two point loading. Out of 16 beam specimens, 8 beam specimens were cast using OPCC and other 8 beam specimens were cast using GPC. The size of all the 16 beam specimens were kept constant as 150mm × 200mm × 1500mm. All the beam specimens are divided into major two category, plain cement concrete beams (PCC) and reinforced concrete (R.C) beams. Further the beam specimens are divided into sub category, Non-Prestressed concrete beam and prestressed concrete beam. Each category of beams were cast using OPCC and GPC and for each category of beam, two beam specimens were cast. The design of beams was done using IS code provisions. The high tensile strength wire of 3mm - 3 ply was used in prestressed beam. The comparative study of different parameters such as load at first crack, ultimate load, deflection at different interval of load, ultimate deflection, failure modes, crack pattern and load vs strain graph was done for all different category of both OPCC and GPC beams. Based on the experimental work, it was observed that the total deflection of the GPC beam specimens was more than the total deflection of the OPCC beam specimens. From experimental work it was observed that, in case of non-prestressed PCC beam specimens, its load carrying capacity was higher compared to non-prestressed GPC beam specimens. While, prestressed GPC beam specimens had greater load carrying capacity compared to prestressed PCC beams. The failure obtained in prestressed beam specimen for both GPC and OPCC was shear type of failure. In case of RC beam specimens, it was observed that for non-prestressed and prestressed RC beam specimens, the ultimate load carrying capacity of the OPCC beam specimen was greater than the GPC beam specimen. The failure obtained in both type of RC beam specimen was flexure type of failure and both type of concrete beam show the same behaviour. It was observed that the value of maximum compression strain in GPC was higher than the OPCC.