Permeability of Concrete Subjected to Cyclic Loading. Volume 1

摘要

Structures like concrete pavements and bridge structures are subjected to dynamicloading at a magnitude that is less the design service load. Their failure occurs due to fatigue of concrete. Prior to the applications of external loads there exist, in concrete, a significant number of cracks or cracks like voids. The cracks formed prior to the application of external loads are primarily bond cracks at the mortar-aggregate interface, with negligible cracking in either the mortar or aggregate phases. Crack propagation in concrete under dynamic loading has three different stages: stage I, the crack initiation, which begins immediately after the load has been applied, stage II or the crack propagation stage and stage III, the rapid crack propagation period. Microcracks exist during all three stages, deteriorating the structural integrity of concrete, whose density increases as the macro crack continues to propagate. These microcracks exist near the tip and around the micro crack. As the durability of concrete is mainly dependent upon its resistance to the ingress of various fluids and gases, it is very essential to know the effect of microcracking on the permeability of concrete at every stage of its life. The experimental work carried out in this study is designed to investigate the deterioration of concrete in terms of its permeability in the stressed zones.