BEHAVIOUR OF FERRO-FIBRO-CRETE PAVEMENTS UNDER IMPACT LOADINGS

Abstract

It is well known that a brittle cement-based matrix of concrete in service may exhibit failure through micro cracks rising in it in the initial stages and their subsequent propagation. So it has limited resistance to impact loading. Maintaining the concrete structure with the absence of or without the propagation of cracks is of considerable importance in order to prevent the corrosion of steel reinforcing bars. For this purpose fibers and wire meshes are used as reinforcements in the concrete. Ferro cement, considered to be an extension of reinforced concrete technology, has relatively gained importance due to its better mechanical properties and durability than ordinary reinforced concrete. Ferro cement is a composite material consisting of cement, coarse sand and wire mesh is impregnated with rich mortar mix. From studies it has been established that when mortar is reinforced by short closely spaced fibers, acts as a better crack arrestor. Ferro-fibrocrete is the ferrocement with short discrete fibers randomly dispersed in the cement sand matrix. Therefore the Ferro-fibro combination helps in maintaining the cracks tightly closed due to crack arrest properties. Concrete pavements in highways are subjected to million cycles of repeated axle loads from trucks and automobiles. Therefore the impact and fatigue characteristics are important to study and require to be dealt with separately. When the structure is subjected to repeated loading during its service life, the design should be based on its impact and fatigue loading. Effect of Impact by moving traffic is acted in two different modes i.e. compression and flexure.