ACCELERATED CORROSION LABORATORY STUDIES IN FERROCEMENT

Abstract

Ferrocement has gained wide popularity as an efficient form of construction material over the past two decades preferentially for thin-walled plane and spatial structures. Ferrocement constructions need special care and caution to ensure satisfactory performance over the expected service life, leaving little room for poor workmanship. Because of the similarity in the nature of the ingredients of conventional concrete and ferrocement, the durability characteristics are expected to be similar even though the mechanical characteristics may be quite different. Limited data is available on factors affecting the durability of ferrocement and for predicting Its service behaviour. The aim of this study was to investigate the corrosion behaviour of 224 ferrocement elements, 400mm x 200mm x 20mm in size, by subjecting them to accelerated corrosion using 0%, 3%, 6% and 9% salt solutions (NaCl) for curing the samples under submerged and alternate wetting and drying conditions. The specimens were exposed to these environments for 1, 3, 7, 14, 21, 28 and 60 days. The effect of degree of corrosion on the flexural strength of ferrocement was then studied. Typical wire samples were studied under microscope to assess the nature and extent of corrosion. The results obtained from the study indicate that corrosion shows a tendency of stabilizing after some time. The rate of corrosion or the corroding influences have little effect on the first cracking strength of the specimens. The cummulative corrosion, as measured by and value, does not result in any appreciable loss in the cracking strength unless and assumes a very high value. Effort has been made to co-relate the non-destructive spontaneous potential test results i.e. the electrical half-cell potential of steel in cement mortar to the extent of corrosion. The future of ferrocement and its extended uses, will depend on finding satisfactory solution to the durability aspects