Strength and stiffness of a cement-stabilised lateritic soil with granulated rubber addition

Abstract

Ground improvement via soil stabilisation has been widely applied and proven to be an effective countermeasure for development on problematic soils. The stabilisation procedure usually involves addition and thorough mixing of hydraulic binders with in situ soils, consequently transforming the soft materials into a stronger and stiffer stratum for load bearing. Nevertheless the method can also be adopted for reusing and strengthening clayey soils, such as laterite, for the construction of road foundations. Recycling and reuse of waste materials, such as granulated rubber processed from waste tyres, should be considered for developing alternative soil stabilisers. Each new combination of stabilising agents introduced needs to be carefully examined in terms of the stabilised material's enhanced properties, especially the strength and stiffness of the targeted soil, as different soil types are known to react differently with different stabilisers. This paper presents experimental test results of a lateritic soil (clayey sand) stabilised with 0–4% cement and 0–4% rubber chips or rubber shreds. In the study, unconfined compressive strength tests were complemented by elastic (i.e. P- and S-) wave velocity measurements. The corresponding strength and stiffness of the various mixes were analysed and discussed in this paper. Correlations between the parameters investigated were also established to shed light on the improved soil properties. Both strength and stiffness of the stabilised soil were found to be predominantly controlled by cement content, although higher rubber dosages were observed to increase the ductility of the stabilised material. Furthermore, the form of the rubber addition, as either chips or shreds, did not appear to have a significant effect on the response of the stabilised material. In short, results from the unconfined test series highlighted the potential of cement–rubber as an alternative stabilising agent for similar lateritic soils, specifically in terms of strength and stiffness improvement. Long-term durability of the stabilised material however, with relevance to exposure to the elements and various site conditions, needs to be addressed in follow-up investigations to ascertain the site applicability.