Inhibition of wire mesh corrosion in Ferrocement

Abstract

Durability of ferrocement is mainly governed by the decay rate of reinforcement since the diameter of the wire mesh used, is much smaller as compared to the conventional reinforced cement concrete. Under aggressive environment, the problem of corrosion of meshes in ferrocement becomes more damaging. With the passage of time the effective strength of the wires gets reduced due to reduction in diameter and also the bond between the matrix and reinforcement gets affected. It happens mainly due to the corrosion of wire meshes. In the present study an attempt has been made to improve the corrosion resistance of the metallic wire meshes used in ferrocement by using corrosion inhibitors. Two corrosion inhibitors viz. Calcium Nitrite and Tannic Acid were used. The dose of inhibitors was kept as 1, 3 and 5%. Tests were undertaken for mild steel plate and welded steel wire meshes under normal (tap) water, saline water (distilled water mixed with 4% NaCl), tap water with inhibitors and saline water with inhibitors. Wire meshes were exposed to two conditions viz. naked state and cement slurry coated state. Potentio-dynamic polarization tests were also conducted with saline water as medium using Calcium Nitrite and Tannic Acid. Excellent corrosion inhibition has been observed for Calcium Nitrite both for mild steel plate specimens and the welded wire meshes. Reasonable corrosion inhibition efficiency is found for Tannic Acid. The Potentio-dynamic polarization tests further validate the suitability of these inhibitors for checking the corrosion of fibres in composites. © 2006 by School of Engineering and Technology, Asian Institute of Technology.