Moisture Content-Based Longitudinal Cracking Prediction and Evaluation Model for Low-Volume Roads over Expansive Soils

Yaqi Wanyan,Imad Abdallah,Anand J Puppala,Soheil Nazarian

doi:10.1061/(asce)mt.1943-5533.0001217

Abstract

AbstractThis paper summarizes a methodology for using moisture content (MC) together with soil index properties to study and predict the progression of longitudinal shrinkage cracking (LSC) along low-volume roads through finite-element analysis. Extensive laboratory tests were performed on soil samples retrieved from six representative clayey sites in Texas, including five high plasticity index (PI greater than 25) sites and one low-PI site. Field measurements of moisture content, suction, and crack development were carried out at five representative farm-to-market roads constructed over the high-PI clayey materials in southern and eastern regions of Texas for verification. Compared to the prevailing suction-based approach, the MC-based approach offers more flexibility in terms of incorporating different drying/wetting paths into numerical modeling by laboratory-based material constitutive models. The estimated critical moisture content thresholds and locations of LSC showed good agreement with the field ...

Highlights

Introduction and BackgroundExpansive, high-plasticity soils exhibit significant mechanical property changes throughout seasonal drying and wetting cycles and cause different types of distress in the lightweight structures built over them
Both models showed that the base–subgrade interface had a higher frequency of initializing longitudinal cracks and that the greatest tensile stresses were usually developed within the top 0.13-m (5-in.) of the subgrade
Damage caused by subgrade shrinking is less severe for four-layer pavements, but the maximum σss is close in magnitude

Summary

Introduction

High-plasticity soils exhibit significant mechanical property changes throughout seasonal drying and wetting cycles and cause different types of distress in the lightweight structures built over them. Low-volume roads, as a significant part of our transportation system, often face frequent maintenance and premature failure in expansive subsoil regions. A Texas Department of Transportation (TxDOT) survey was conducted in 2008 (Wanyan et al 2008a) to gather expert opinions on best practices in pavement design, construction, and maintenance that might extend the life expectancy of these low-volume roads. Eighteen out of 25 districts reported having high plasticity index (high-PI) clayey subgrades that cause frequent pavement construction and maintenance problems. Among different types of flexible pavement distress, longitudinal cracking was ranked the most prevalent distress encountered on high-PI clayey subgrades. The consensus among the experienced practitioners was to maintain the MC as constant as possible in the areas with high-PI clay subgrades

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Conclusion