Assessment of clay soil fabric using scanning electron microscope (SEM)

This paper introduces the way of assessing the soil fabric using outlines given by Collins and McGown (1983).The physical and mechanical properties of soils depends particularly on their fabric. At micro levels, the fabric of a soil sample consists of different elemental particles as well as it does at visible range of view. The arrangements of elementary particles and their sizes and shapes predict its mechanical behavior and characteristics. One of the best ways to recognize the fabric of a soil sample is to utilize scanning electron microscope. In this paper first the fundamental alphabets of scanning electron microscopes are explained then the soil fabric classification system given by Collins and McGown is fully described. Three clay soil sample were selected. Six specimens were prepared for swelling test, three of them without any treating agents and remains were treated with apolymeric agent. After applying swelling test according to ASTM D-4546 the samples were scanned using scanning electron microscope (SEM) and 18 micrographs were taken. For clarifying the terms used in the classification system, all micrographs were fully interpreted

Reduction of swell pressure of expansive soils using some polymeric additives

The main objective of this study is to evaluate the effect of three polymeric additives on swelling properties of expansive soils. Three clayey soil samples were used in this study. One of them are of moderate and two of them are of high plasticity index. Furan, Methyl Metha Acrylate (MMA) and Vinyl Acetate (VA) have been used as three polymeric additives in this study. In order to evaluate the effect of these polymers on swelling pressure of afore mentioned soil samples firstly a series of swell pressure tests (using ASTM-D4546) were applied on untreated soil samples at optimum water content. Then each untreated soil sample was mixed with each of the polymers at three different dosage and swell pressure tests were applied at optimum water content. The results showed significant reduction in swelling pressure of these soils. It is also appeared that the efficiency of these polymers to reduce the swell pressure of expansive soils depends on the plasticity index of the soil, type of polymer and the percentage which is used

Effect of polymers on swelling potential of expansive soils

This paper introduces new soil stabilisers for reducing the swelling potential of expansive soils. In this study three different polymers (Furan, Poly(methyl ethacrylate) (PMMA) and Poly(vinyl acetate) (PVA)) were utilised as soil stabilisers. For evaluating the effect of these polymers on swelling potential and microfabric of expansive soils, three soil samples of high plasticity index were selected. First the engineering, chemical and mineralogical characteristics of the untreated soils were determined, and three different pairs of dry density and water content (dry of optimum, optimum and wet of optimum) were chosen, from standard Proctor compaction curve. Treated soil specimens were prepared at 3%, 5% and 10% of furan content and 1%, 3% and 5% of polymethyl methacrylate and polyvinyl acetate content. The addition of polymethyl methacrylate and polyvinyl acetate can also diminish the swelling potential of soil specimens, but to alesser degree. The addition of additives produced aggregations and clay-granular matrices within the fabric, which reduced the swelling potential of the soil samples