ANALYSIS OF CONCRETE PAVEMENT ON EXPANSIVE SOIL

Abstract

Analysis of concrete pavement on expansive soil susceptible to expansion and shrinkage with chance of different moisture content is a constant source of trouble in the design and construction of foundations such soils popularly known as black cotton soil and collapsible soil occur extensively in countries like India. In India there are various states like Maharashtra, Madhya Pradesh, Andhra Pradesh and Tamil Nadu. Expansive soils are susceptible to volume change, and thus for the construction of rigid pavement as well flexible pavements over them, they need to be stabilized to increase load carrying capacity without undergoing excessive volume change, which can be catastrophic in nature. Economy has always been a top consideration factor before carrying out construction of any kind. Achieving higher values of the strength parameters, with a controlled increase in cost of the foreign material leading to an overall decrease in the net construction cost, are always a sign of development. To improve the mechanical properties of soils, a variety of materials are used for reinforcement e.g. metallic elements, geo synthetics etc. the products generally have a long life and do not undergo biological degradation, but are liable to create environmental problems from their manufacture till the end use. In effecting this use of biodegradable natural fibers is gaining popularity. Now days, waste material are produces in abundance. These waste materials can be utilized in the stabilization of soils. Waste materials like fly ash, plastic waste, slag comes from iron ore industries and other manufacturing plants. Various researches have been conducted on soil stabilization using these foreign materials. In the present study, the expansive soil is treated using mixtures of lime and fly ash in different proportion to achieve the best mixture. In our study mixtures of treated are tested for liquid limit, plastic limit, optimum moisture content, maximum dry density, free swell index and unconfined compressive strength. Soil sub-grade. Rigid pavements are constructed of Portland cement concrete. The first concrete pavement was built in Bellefontaine, Ohio in 1893.they consist of three layers i.e. surface layer, base layer and the sub grade. The rigid pavements have high flexural strength and can resist very high tensile stresses. Rigid pavements possess note worthy flexural stiffness or flexural rigidity. These pavements transfer load through slab action but not grain to grain transfer as in case of flexural pavements. These consist of three layers namely-cement concrete slab base course They are made of Portland cement concrete either plain, reinforced or pre –stressed. The plain cement concrete are expected to take up about 40kg/cm2 flexural stress. These are designed using elastic theory, assuming pavement as an elastic plate resting over elastic or a viscous foundation. Expansive soils present problems to engineers in the construction of durable roads. The v two main concerns are shrinking, swelling of clays and changes in material properties under a range of moisture conditions. Volume changes in expansive soil can be signification and occur as the moisture content changes. Low volume roads constructed on clay sub grades are a particular challenge to engineers because the volumetric changes cause instability of the road, resulting in an uneven pavement surface, detrimental cracking and ultimately, premature deterioration and replacement. However, as the moisture increases, the plasticity of the clay increases and strength decreases. Hence, significant maintenance or premature road replacement would be often necessary.