ASPHALT CONCRETE PAVEMENT WATER DAMAGE CHARACTERIZATION AND MODELING

Abstract

Asphalt concrete road construction is an essential measurement for the development of a country by providing comfort for the road users and it also protects the sublayers from early damage by water and traffic load. Due to the allocation of huge budget for the road sector a large numbers of roads are being constructed and under construction. Among the road pavement layers the asphalt concrete pavement is the most expensive layer and it needs an intensive care during design and construction time. Most of the roads constructed in the country are failing before serving the expected design period due to moisture condition, excess traffic load, material quality, operational problem and asphalt concrete mix design problems. From the causes of pavement failure parameters moisture damage contributes larger percentage for the formation of rutting, pothole formation, fatigue cracking, striping, raveling and pumping effect. Moisture damage in Asphalt Concrete (AC) is not new but an unsolved problem. For decades laboratory studies have been conducted on both loose and compacted mix to understand the effects of moisture on the AC damage. Adhesive and cohesive damages are the two major types of damages occur inside the AC. In this study an asphalt concrete mix design is prepared using marshall method after optimum bitumen content is identified. Then, the mix design is checked for moisture sucpetibility test using Indirect Tensile Strength Test and Hamburg Wheel Tracking Test Methods. Then finally using Finite Element Modeling (FEM) a simulation model is developed by verifying with the laboratory test results using density, Elastic Modulus and Poisson ratio parameters. In the ITS test result the moisture is affected the sample by 9% while in HWTT the moisture affected the sample by more than 39%. It is also seen that when the air void of the mix is increased the rutting formation also will be increased and it will be more exposed for moisture damage. ANOVA test is conducted to check the correlation among experimental data and model out puts, they have large correlation for both ITS and HWTT. Thus, the FEM model predicts the experimental data more closely and so the model can be used as a reference for other similar Asphalt concrete mix designs which are having the same material properties and environmental conditions.