Study on Corrosion Effect and use of Different Types of Bar as Reinforcement for Beams

Abstract

Majority of steel reinforcement that we use in practice have lugs or protrusions on the surface. The protrusions on the surface of reinforcement bars is beneficial as it increases the bond capacity between the rebar and the surrounding concrete. These protrusions were an added advantage and were introduced on the surface of plain Mild steel bars to prevent the slippage of reinforcement and in turn increase its bonding strength. But the protrusions on the surface of the HYSD cause excessive corrosion in the rebar and distress in the concrete structure. PSWC bar can possibly be a viable solution for the early distress in the concrete structure. The bars with a plain surface and a wavy type configuration are known as PSWC bars. The PSWC bar is characterized by its plain surface and a gently undulating wave-type configuration. PSWC bar was formerly known as C-bar.

A comprehensive experimental program, inclusive of flexure testing of 10 numbers of Beams, involving PSWC bars, plain bars and HYSD bars with various grades of steel (Fe 500, Fe 500 D), and Epoxy Coated bar (Fe 500), is planned for the present study. Breakup of these configurations is as follows: 14 beams (with 2 each of 5 different rebars) viz, plain round bar, ribbed bar (Fe 500), ribbed bar (Fe 500 D), ribbed bar (Fe 550D), PSWC bar (pitch 30d, offset 5mm), Epoxy Coated (Fe 500) are to be cast. All beams are of 160mm x200mm and 2000mm in length.

Beams are designed as per IS: 456:2000 and SP-16 provisions. Concrete grade is kept as M25; the reinforcement detailing and design is kept same for all beams. Self Compacting Concrete (SCC) of M25 grade with OPC, Fly-ash (25 % replacement), only 10mm aggregates, river sand, potable water, and super plasticizer is used. Mix design is finalized based on EFNARC guidelines. Various trials were carried out to finalize the mix proportion for Self Compacting Concrete (SCC).

Vertical Load on the beams is applied at specific load intervals of 10kN. Corresponding To every load, displacement and longitudinal strain at different positions on top as well as bottom side of beams is measured. Failure pattern of beam from propagation of first crack up to failure is observed and presented with necessary photographs.

Comparison of ultimate failure load, maximum displacement, longitudinal strain and experimental crack width are presented for all categories of beams. These parameters are very essential to understand the behaviour of the beams with different strengths and types of rebars.

A higher load carrying capacity was observed in the PSWC bar as compared to Plain round bar. The reason behind the higher load carrying capacity is wave configuration of PSWC bar. Another reason for higher capacity of R.C.Beam reinforced with PSWC bar is, the wavy configuration of PSWC bar increases the effective bond with concrete. So PSWC bar helps shear as well as flexural load carrying capacity of RC Member.

Deflection of Beam Reinforced with Fe 500 and Fe 500D is lesser as compared to beam reinforced with PRB, PSWC, ECB, and this trend is clearer because Beams reinforced with PSWC, ECB and PRB are more ductile as compared to beam reinforced with Fe 500 and Fe 500D. So incorporation of PSWC bar in beam make the beam element more ductile. The study also presents an investigation to evaluate the efficiency of Phyllanthus emblica (Indian gooseberry) lives extract as a Green Corrosion Inhibitor. To assess the performance of the P. emblica extract, an accelerated corrosion test is to be performed on RC specimen which incorporates P. emblica extract as an inhibitor. Corrosion is to be monitored by corrosion monitoring techniques i.e. half-cell potential, and corrosion inhibition efficiency. After performing accelerated corrosion in RC specimen, a bond test and tension test is to be performed on the corroded specimen and a comparison of its behaviour with uncorroded specimen is formulated.