Pavement Evaluation of Mbagathi Road, Kenya

Abstract

Mbagathi Road has been open to traffic for six years and yet various distress features have been observed despite the fact that most concrete roads are expected to operate for over twenty (20) years without any major maintenance and without exhibiting any distresses. The objectives of this research was to determine the relationship in the observed pattern of deterioration of Mbagathi Road with the performance of concrete slabs forming part of Mbagathi Way, to conduct a pavement condition survey and to determine magnitude and pattern of deflection of pavement slabs. This thesis describes a literature review, studies on concrete road deflections, pavement condition survey, traffic loading on Mbagathi Road and analysis of results that provides baseline information on the performance of Mbagathi Road. The assumption by Westergaard of infinite or semi-infinite slab was in tandem with this research and hence the applicability of these equations is not in doubt. This research concurred with other researchers who observed that as a/I increase, finite element stresses and deflections become progressively higher than Westergaard's. In addition, the pattern of observed deflections were similar the progression of Westergaard's deflections. It was found that Mbagathi Road is weaker than the ideal Westergaard assumption. However, despite the fact that high noise levels were observed on Mbagathi Road, the determination of homogenous section through pavement condition surveys and measurement of pavement deflections yielded correlated results. Pavement deflections were directly proportional to the overall pavement condition and drainage conditions influenced, to a large extent, the overall pavement condition in terms of the occurrence of distresses. Homogeneity of concrete influences the degree pavement deflections while the performance of Joints indicated.performance of concrete pavements. Despite the observed weaknesses, Mbagathi Road is expected to survive its intended life without major deterioration. special attention must be paid to drainage conditions which were found to indicate eminent failure of the pavement. Resealing of observed cracks will reduce percolation of water into the pavement layers and hence prolong the life of the pavement.