MECHANISTIC ANALYSIS OF EARLY PAVEMENT DETERIORATION: APPLICATION TO THE GASSI - DOURBALI SECTION

This work deals with the empirical mechanistic analysis of pavement behaviour: application to the Gassi - Dourbali axis in Chad. It consists of carrying out a study to determine the probable causes of the deterioration observed on the section in question, and of recording the deterioration. Test pits on the asphalt section, distributed according to the severity of the deterioration, will be used to determine the thickness of the various layers of pavement and their geotechnical characteristics. Deflection measurements will be carried out over a distance of two thousand (2000) metres and on particularly deteriorated areas in order to determine the residual capacity of the pavement. The traffic study included a 3-day vehicle weighing campaign and a counting campaign at at least three (03) stations for a period of seven (7) days. Based on the information available, we reviewed the project from its conception to its completion, and even its termination. The main reason for the work being halted was the early deterioration of the first 54 kilometres of asphalt. What went wrong?The Deming wheel is a tool for analysing and diagnosing projects. Plan Do Check Act is a question and answer method. It has enabled us to plan our actions, namely: surveys of deterioration, the organisation of traffic counts, the axle weighing campaign, and then the launch of geotechnical tests. Following an analysis of the rutting mechanism, recommendations are proposed to reduce the risk of rutting and to repair the pavement. Cracks appearing on the surface as a result of the combined causes we have listed are accentuated by rain, wind and vehicle movements, which crumple the earthenware and cause it to break up into debris or masses.