BUCKLING BEHAVIOUR OF THIN FERROCEMENT PLATES

Abstract

Ferrocement seems to be a progressive material in that its applications range from extremely simple handwork to machine-based mass production. It is basically, a low cost and highly labour intensive material. Ferrocement is a composite material consisting of a matrix (cement-sand mortar) and a reinforcement (wiremesh) which act together to form a new material with characteristics superior to those of its constituents. Extensive research on the subject has already brought out its characteristics of ease of construction, improved tensile properties, high resilience, ability to take large deflections, high static ductility, high compressive strength, high resistance to cracking, improved toughness, fatigue resistance, impermeability, reduced dimensions, vibration resistance, light weight, fire resistance and economy as compared to reinforced concrete. However, very little information is available on shear strength of ferrocement. An experimental study was planned to study the behaviour of thin ferrocement plates under uniform in-plane loading. The results of total six plates of thicknesses 60, 25 and 15 mm (2 each), 2 m x 0.9 m, with two mesh layers and skeletal steel are presented. Specimens were tested as deep beams under vertical in-plane loading. iv The results of the study show that no buckling takes place. The failure is because of flexure and shear. The strain variations were non-linear and neutral axis did not remain in the centre. Vertical deflections were of the range 4 mm to 5 mm. Maximum crack width was 0.10 mm. Both these values are within the limits prescribed by IS:456-1978 and the ACI design guidelines for ferrocement. Two empirical equations have been developed to find the first crack load and ultimate load. More investigations are required for arriving at definite conclusions.