Effect of Xanthan Gum Biopolymer on Engineering Properties of Expansive Soil

Abstract

Expansive soil is one of the problematic soil and structures found on this type of soils undergo various problems. In modern day lime, cement and various chemicals are used for treatment of expansive soil. But from environmental view this type of admixture have several shortcomings. Present study demonstrates an experimental investigation on expansive soil behavior,under treatment of xanthan gum (XG) biopolymer. The effectiveness of XG biopolymer have been studied by investigating the plasticity, swelling, consolidation strength and durability
behaviour. The xanthan gum biopolymer is mixed with expansive soil in different proportions such as 0, 0.2, 0.5, 0.8, and 1.0% by weight of the dry soil mass Atterberg limit have been calculated to understand the plasticity characteristics. The liquid limit, plastic limit and shrinkage limit shows increasing value on the other hand plasticity index (PI) of the treated samples decreases slightly. The optimum moisture content (OMC) and maximum dry densities (MDD) have been calculated by performing light and heavy compaction test. The OMC of light and heavy compaction goes on increasing with increasing biopolymer concentrations whereas, the MDD decreases in light compaction and in heavy compaction it reverses. Swelling pressure (SP), differential free swelling index (DFS) and consolidation test have been performed to understand the swelling behaviour and consolidation behaviour of the treated soil. The DFS, coefficient of compressibility (Cc) and swelling index (Cs) value increases slightly but, after 7 days curing the DFS value reduced by 54.05% from the virgin soil. XG addition to the expansive sol reduces the hydraulic conductivity and swelling pressure moderately. The strength behaviour have been investigated by conducting the unconfined compressive strength. The UCS samples are compacted at OMC and MDD of heavy compaction and curing has done for 3, 7, 28 days. The 3 days cured and 28 days cured UCS samples shows an excellent improvement in strength such as 18.6 and 93.2% respectively. For durability test the freeze/thaw durability test have been performed. The result shows that in each cycle the mass loss and moisture content loss in treated sample decreases substantially. Scanning electron 14 microscopic (SEM) test have been performed to indicate the formation of gel like linkage. Which confirm the increase in strength and durability of the treated samples.