Ultra-thin engineered cementitious composites overlay systems for rehabilitation of rigid concrete pavements

In recent years, the use of rigid concrete overlay has become increasingly popular in bridge deck, highway and airport pavements and industrial floor rehabilitation. The main purpose of an overlay is to extend the service life of the structure by providing protection from the penetration of aggressive agents and water and a durable wearing surface. Moreover the overlay provides adequate load bearing capacity, which is compatible with the loading of the pavement and bridge deck. The superior ductility and improved durability characteristics of Engineered Cementitious Composites (ECC) suggest that they could be used as an attractive alternative to conventional overlay materials. In this study, the performance of ECC as pavement overlay material with different thicknesses is investigated. Two different ECC-overlay mixture designs are investigated: one with high strength and moderate ductility, and the other with moderate strength and high ductility. Micro-silica concrete (MSC), generally used as overlay material, is also prepared as a control mixture. For monolithic specimens, compressive strength, flexural strength, drying shrinkage and restrained shrinkage, and for layered specimens flexural strength and reflective cracking characteristics are investigated as performance criterias, respectively. The test results show that, for the same geometry and loading conditions, layered ECC beams have a significantly increase of both load carrying capacity and deformability by deflection at ultimate load, and shows better crack width control in comparison with MSC composite beam.Keywords: Pavement overlay, Engineered Cementitious Composites (ECC), Reflective cracking, Flexural performance.