Consideration of Moisture Effect on Load Bearing Capacity in Texas Flexible Pavements

Abstract

Variation of moisture content within substructures of pavements plays a key role in controlling load bearing capacity tied to adjust strength parameter and resilient modulus of subsoil layers to corresponding moisture level. This paper presents efforts to develop the LoadGage computer program for estimating pavement load bearing capacity accounting for in-situ moisture condition. From results of plate bearing tests, it was observed that the current modified triaxial design method which has been adopted by the Texas Department of Transportation (TxDOT) as a design check procedure relatively underestimates pavement load bearing capacity. In view of the moisture conditioning that samples undergo in the existing triaxial test method, the adjustment of subgrade strength parameters based on the soil-water characteristic curve provided a rational approach for considering the difference in moisture conditions between laboratory tests conducted to characterize strength parameters for pavement design and the field conditions expected in-service. Validating the LoadGage program was achieved via a series of plate bearing tests, and it revealed reasonable estimations compared to field observations especially in pavements built with stabilized layers.