MASTIC ASPHALT AS A WEARING COURSE

Abstract

Experience over long periods and laboratory research have resulted in improving the properties of mastic asphalt by the addition of suitable percentage of ingredients, particularly for surfacing on slopes•, slurry seals, and bridge deck surfacings. It is equally important to produce a mastic asphalt with inherent non—skid properties. In general high grade mastic asphalt can be produced by accurate and constant percentages, controlled and careful heating and mixes selected for the particular use. The high cost to a great extent can be neutralized by mechanisation and mass production. It is important to realiSe that asphaltic mixtures by their carefully controlled specifications and by their ability to vary their constituents are particularly adapted to solve the difficult problems presented by bituminous wearing bourses on modern city pavements carrying heavy traffic. As a paving material, mastic provides a tough, durable wearing surface capable of withstanding heavy loads and stresses, even such as turning of tracked vehicles. It requires no compaction while placement. Further, it can be opened to traffic in a short period. It acts as an insulating layer against the water. The major disadvantage of this are poor skid resistance and hi& cost, The skid resistance can be overcome by use of spiked roller to form waffle pattern or by rolling in precoated aggregtces while the surface is still hot, The long surface life and low maintenance can offset the high cost, In this dissertation efforts have been made to study the stability of mastic asphalt and to identify the means to how best this mix can he used not only for wearing courses but also for other special applications such as surfacing of bus stops, canal linning, seal coat, protection from crossion etc in which its properties like durability, impermeability and stability pan be exploited to the hilt. In fact it Possesses all the ideal properties like durability, stability and self healing characte- ristics required for a wearing course except for skid resistance. In order to achieve the objective, unconfined compression test has been done at various temperatures and at four different rates of loading. Alongwith this the properties of mix like dynamic modulus of elasticity were found by sonic method. The triaxial test was also done to find out cohesion of the mix, Finally, a computer programme was developed which can he used for design of this mix,