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A series of experiments were carried out to investigate the behavior of cementstabilized fiber-reinforced clay with different cement and fiber contents. Three groups of tests were conducted, on: (1) reinforced samples with four different fiber contents (0.5%, 0.75%, 1% and 1.25%); (2) cement-stabilized samples with three different cement contents (5%, 8% and 10%); and (3) cement-stabilized, fiber-reinforced samples with the same fiber contents as the uncemented reinforced samples. Unconfined compression tests (UCT) were carried out on the uncemented samples. These UCT tests were also conducted on the cement-stabilized samples with and without fiber inclusions after 3, 7, 14 and 28 days of curing time. The results indicated that the inclusion of fibers within uncemented and cement-stabilized soil caused an increase in the unconfined compressive strength and axial strain at failure, and changed the brittle behavior of the cementstabilized soil to a more ductile behavior. It was also shown that the mechanical characteristics of the soil-cement-fiber mixtures are functions of fiber content and curing time.

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An investigation into the behaviour of a contaminated clay soil and its treatment was showed that adding cement to contaminated soil increases the strength and the amount of increase in strength is dependent on the percent of cement, curing time and degree of contamination. Based on SEM analysis, it was found that the presence of glycerol prevents from interaction between soil and cement.

This paper presents the results of treatment of an expansive soil by mechanical and chemical techniques against swelling. Mechanical treatment was done by reinforcing the soil with randomly distributed fibres and chemical treatment by using cement or lime as a chemical agent. All the experiments on untreated and treated samples were conducted in an oedometer. The experimental programme consisted of two groups of tests. The first group involved the tests on expansive soil reinforced with randomly distributed fibres (mechanical improvement) with different percentages (0.5, 1 and 1.5%), and different lengths (10, 20 and 30 mm), in bar shape with diameter of 0.30 mm or tape shape with two different widths (3.0 and 5.0 mm). The second group of tests consisted of samples that were mixed with different percentages (5, 8 and 10%) of cement or lime (chemical improvement) for different curing times. The results showed that, compared with the natural soil, the swelling behaviour (swelling potential and swelling pressure) was reduced by adding randomly mixed discrete fibres. The reduction of swelling potential and swelling pressure is also a function of percentage, length and type of fibre (bar or tape shape). The results also indicated that the addition of cement and lime caused reduction in swelling potential and its effect was considerably more than the influence of fibre. The effect of chemical agent is also a function of percentage of the chemical agent and the curing time.