Strengthening of Shear Deficient Reinforced Concrete Beams Using Polymer Modified Ferrocement PMF

Abstract

There is a common phenomenon of shear failure in RCC beams, especially in old buildings and bridges. Any possible strengthening of such beams needs to be explored that could strengthen and make them fit to fulfil the strengthcriteria. The present research has been carried out to determine the performance of polymer modified ferrocement (PMF) used to strengthen the pre-damaged RCC beams. Ferrocement has become a universally acceptable thin composite material in the field of construction technology. This is primarily due to its better strength to thickness ratio. In the present research work, the polymer modified ferrocement has been used to strengthen the beams as it had been come of age in the last two decades or so and has found that the conventional ferrocement made with cement mortar matrix does not exhibit significant durability. Hence, two types of polymers were chosen toadd in the mortar matrix to improve the properties of traditional ferrocement. As a pilot study, the effects of addition of Vinyl-Acetate-Ethylene (VAE) polymer and Styrene-Butadiene-Rubber latex (SBR) polymer on the properties of mortar and ferrocement have been studied. The polymer-modified mortar (PMM) matrices were prepared by adding different percentages of polymers varied from 0% to 20%. Cement-sand ratio for mortar was fixed as 1:2 and water-cement ratios have been also worked out for a specified flow value of 105±5%. The compressive strength, workability, flexural strength,air content and Young s modulus of elasticityof PMMs was worked out by conducting the various tests. Test results showed that the mortars modified with polymers showed better performance performed as compared to un-modified mortars. Further, the polymer modified ferrocement (PMF) elements were cast with different volume fraction of reinforcement consisting of 2 and 3 layers of wire mesh.