INCREASING MOISTURE CONTENT AS FAILURE RATE PROPAGATOR OF HOT MIX ASPHALT PAVEMENT USING FRACTURE MECHANICS

Abstract

The design and construction of safe and durable roads is a necessity to promote national development. The challenges encountered with roads design and construction industries worldwide is the high financial implication for quality and durability. This study proposes a new approach for modelling the nonlinear elastic behavior of Hot Mix Asphalt using fracture mechanics (a principle concerned with the propagation of cracks in material elements). This is achieved by simulating crack propagation or crack growth in asphalt pavements using a bottom-up crack growth progression. However, time rate delamination of flexible pavement is of paramount importance. There is a need to determine a safer and sustainable means of predicting and determining the performance of roadways before, during and after its construction. This will result to cheaper road design and analysis, effective maintenance measure and reduced cost of maintenance. This study is on time rate delamination of flexible pavement, the effect of Moisture/Hydraulic Coefficient, temperature variation and stiffness ratio of the pavement. Consequently, adaptive meshing is used in the Axis-Symmetric model followed by a model for nonlinear viscoelastic behavior of Hot Mix Asphalt and simulating crack propagation in asphalt pavements using Griffith energy criterion. The findings indicate that there is a strong relationship between environmental condition (moisture content) and Asphalt Concrete resilient Modulus. Increasing temperature and moisture content results to reduction in pavement strength. Thou the failure is not visible at the onset of crack propagation (crack tip), but continual exposure to increasing temperatures as well as increasing moisture content will lead to failure of the pavement before the design life is attained. Furthermore, there is also a strong linear relationship between Griffith strain energy and the Pavement Resilient Modulus.