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Efficacy Of Cement-stabilized Gbs And Ggbs Cushions In Improving The Performance Of Expansive Soils

Last Update2016-09-05
TitleEfficacy Of Cement-stabilized Gbs And Ggbs Cushions In Improving The Performance Of Expansive Soils
Author(s)Author #1
Author title:
Name: Sridevi Guda
Org: Professor, B.V. Raju Institute of Technology, India

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KeywordsExpansive soil, Ground granulated blast furnace slag, Cushion, Heave, Swelling potential, CBR
AbstractExpansive soils undergo alternate swelling and shrinkage with changes in the moisture regime. As a result, structures founded in these soils undergo distress. Among the several techniques available to mitigate the problem, CNS layer technique is the one commonly adopted. Since this technique has certain limitations, an alternative method was tried with stabilized blast furnace slag for better results. Granulated blast furnace slag is one of the major by-products of steel plant industry. The disposal of it poses a big problem which, if not solved, causes environmental pollution. Detailed laboratory studies were carried out on this material to investigate its suitability as a construction material. Experiments were conducted to study the effect of the cement content as well as the cushion thickness on the heave of the expansive soil bed. Expansive soil for the study was collected from a depth of 1.5 m in order to see whether it contains no organic matter. The liquid limit is 73% and the plasticity index is 45%, which are very high and show that the soil has high potential for undergoing volume changes. A free swell index of 150% shows that the soil has a high degree of expansiveness. The expansive soil was compacted to its MDD at OMC and above it cement-stabilized blast furnace slag in the form of a cushion compacted to MDD at OMC was placed and the resulting heave was measured. Cement content, varying from 2% to 10%, with increments of 2% by weight, was added to GBS in dry condition and mixed thoroughly. Then, water corresponding to OMC was added and the layer placed above expansive soil bed and compacted to its MDD. Experiments were conducted for different thickness ratios of soil (ts) and cement-treated GBS (tc) given by tc/ts = 0.25, 0.5 and 0.75. Studies were also conducted using cement-stabilized ground granulated blast furnace slag cushion in the same way as mentioned above. It was found that granulated blast furnace slag cushion, stabilized with cement, was effective in arresting heave of expansive soils.
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