STRUCTURAL BEHAVIOUR OF COMPOSITE PAVEMENTS UNDER CYCLIC LOADING

Abstract

In many applications, particularly pavements for highways, airfields, bridge deck overlays and heavy duty Industrial yards, the flexural fatigue strength and endurance limit are important design parameters, because these structures are designed on the basis o f fatigue load cycles. Theoretically, the concrete cross-section could be reduced, with a higher endurance limit. Alternatively, use of same cross-section could result in a longer life span or higher load carrying capacity or both. In recent years, it has been he recognized that the addition of small closely spaced and uniformly distributed discrete fibres in concrete would substantially improve its static & dynamic properties. The addition of steel fibres and/or wire meshes in concrete considerably improve the static flexural strength, impact strength, shear and torsional strength, shock resistance ductility, failure toughness and flexural fatigue strength. Earlier studies have been carried out to determine the fatigue life of various type of concrete mixes but there is no evidence for the fatigue life of different concrete in various layers. In the present study three types of specimen PCC (100mm), PCC-SFRC (60mm - 40mm) and PCC-FFC (80mm - 20 mm) were tested, under cyclic loading. It was found that the engineering properties of composite specimens improve considerably for PCC-SFRC and PCC-FFC composites, Increase in flexural strength under static loading was found to be 7.7% and 12.17%, while in flexural fatigue strength was increased by 8.92% and 13.92% respectively as compared to PCC beam. A computer program was also developed to determine the stress levels in the composite layers. It can further. be improved to predict the fatigue life of composite pavement. Which could not be included here due to time limitation. The economic analysis indicates that the initial construction cost of PCC-FFC and PCC-SFRC pavements is higher but shows greater life expectancy as compared to PCC p