Research Article
E. O. Ekwulo, J. C. Agunwamba
Abstract
Failure of asphalt pavements is generally attributed to fatigue cracking and rutting deformation, caused by excessive horizontal tensile strain at the bottom of the asphalt layer due to repeated traffic loading and excessive vertical compressive strain on top of the subgrade due to densification and shear deformation of subgrade. In the design of asphalt pavement, it is necessary to investigate these critical strains and design against them. This study was conducted to develop a simplified layered elastic analysis and design procedure to predict fatigue and rutting strain in cement-stabilized lateritic base, low-volume asphalt pavement. The major focus of the study was to develop a design procedure which involves selection of pavement material properties and thickness such that fatigue and rutting strains developed due to traffic loading are within the allowable limit to prevent fatigue cracking and rutting deformation. Analysis was performed for hypothetical asphalt pavement sections subjected to traffic load using the layered elastic analysis program EVERSTRESS. Predictive regression equations were developed for the prediction of pavement thickness, fatigue (tensile) strain below asphalt layer and rutting (compressive) strain on top the subgrade. The regression equations were used to develop a layered elastic analysis and design tool (program) LEADFlex. The average ratio of the LEADflex-calculated and measured tensile strains were found to be 1.04 and 1.02 respectively. The procedure was validated by comparing predicted (calculated) fatigue and rutting strains with measured field data using linear regression analysis. The coefficients of determination (R2) were found to be very good with R2 of 0.999 and 0.994 for fatigue and rutting strains respectively indicating that LEADFlex is a good predictor of fatigue and rutting strain in cement-stabilized lateritic base, low-volume asphalt pavement.