Flexural Behavior of Reinforced Concrete Beams with Fly Ash Based Geopolymer Strengthening

Abstract

Geopolymer mortar made from fly ash waste from Steam Power Plant (PLTU) has a higher compressive strength than conventional mortar made from Portland cement. However, geopolymer mortar has a weakness that is brittle. So, it is necessary to add fiber to increase the ductility of the geopolymer mortar. PVA fiber is a synthetic fiber that can be an alternative in geopolymer mortar mixtures, because it has high tensile strength. This study aims to analyze the flexural behavior of reinforced concrete beams strengthened with geopolymer mortar with the PVA fiber addition. The research stages were divided into two, namely compressive strength test of geopolymer mortar and beam flexural test with length of reinforcement of 1500 mm. The compressive strength test of geopolymer mortar used a cube sample measuring 50x50x50 mm which was tested at the age of 3, 7 and 28 days. The beam flexural test used 10 beams with a size of 150x200x3300 mm, consisting of a control beam and the RC beam reinforced with geopolymer mortar (with and without the PVA fiber). The results showed that the addition of 0.6% PVA fiber to the geopolymer mortar increased the compressive strength by 39.23% at the age of 28 days. The application of geopolymer mortar on RC beam strengthening increased the ductility up to 71% compared to the control beam.