Roads in Malta : the effect of heavy rainfall on local pavements

Abstract

Soil mechanics is a vast topic in which the material characteristics are continuously varying and dependent on the amount of water contained within the material. It is a well known fact that local roads experience increased deterioration after periods of heavy rainfall. Limited knowledge exists about the movement of volumes of water into and out of road pavement layers - a phenomenon which can be detrimental to their failure. This dissertation focuses mainly on the effect of water present within the pavement structure. After studying pavements' behaviour, construction, maintenance and deterioration in general, a more detailed investigation about the present state of local pavements was done to try to understand more reasons behind their condition. This was completed by observing a small number of local pavements. Permeability Tests done on site and Sieve Analysis were the two tests being applied in order to try to arrive to a conclusion on a particular hypothesis which states that the damaged surface parts should have a coefficient of permeability k lower than the undamaged parts due to the increase in the amount of fines present. Hence such tests should conclude if any correlation exists between the surface state of the pavement, the amount of fines present within the pavement structure and the coefficient of permeability of the sub-base found underneath the top surfaces layers. Principally two different schools of thought exist regarding the construction of pavements. These are constantly being referred to throughout this dissertation. The first one assumes that the pavement's top surface is impermeable and hence no water enters the pavement structure while the other gives more meaning to the movement of water within the pavement structure and to drainability issues. However an agreed fact by road engineers is that the presence of water within the pavement structure is vital and can lead to its failure.