Stabilization characteristics of cemented lateritic soil produced with selected cement types

Abstract

It is recognized that different cements have different properties and stabilization effectiveness for different applications. The challenge of using the right type of cement should be a concern for practitioners in civil engineering construction. In this study, an experimental testing programme was conducted to evaluate and compare the stabilizing effects of CEM I 42.5 N, CEM II/B-L 42.5 N and CEM III/A 42.5 N types of cement on some physical and mechanical properties of lateritic soil. Laboratory tests performed on soil mixtures containing the selected cements added to constitute 0, 3, 6, 9 and 12 % of the dry weight of the composite materials include the consistency and compaction tests determined on the basis of fresh mixtures. In addition, unconfined compressive strength (UCS) test on specimens compacted at optimum moisture conditions with the British Standard Light (BSL) compaction effort and cured for 7, 28 and 90 days was performed. In equal proportions, soil mixtures prepared with the different types of cements yielded comparable results in terms of reducing the plasticity index (PI) from values as high as 60 % in untreated state to 5.05 %, 7.05 % and 8.2 % respectively for CEM I, CEM II and CEM III at 12 % cement content. Addition of cement also increased both the maximum dry unit weight (γ_dmax) and optimum moisture content (OMC) of the soil with CEM I cement having the greatest effect while CEM III cement affected the γ_dmax of the soil the least. For example, when compacted with BSH effort, CEM I achieved γ_dmax = 1.95 kN/m³ and OMC = 25 %, while for CEM III, γ_dmax = 1.63 kN/m³ and OMC = 22.6 % compared to γ_dmax of 1.53 kN/m³ and OMC of 21.1 % for the untreated soil. Regardless of the cement type, there was an overall improvement in the strength properties of the lateritic soil represented by a range of 11 – 14 times for UCS and 31 - 62 folds for E₅₀ at 12 % cement after 90 days curing duration in comparison with the untreated soil. While strength gain was higher in CEM I based mixtures at early (7 day) age (1635.44, 1622.85 and 1599.55 kN/m2 for CEM I, CEM II and CEM III respectively at 12 % cement content), CEM III provided superior strength improvement at the long term (90 day) curing period (2566.25 compared to 2444.58 and 2465.77 kN/m² respectively for CEM I and CEM II at 12 % cement content). Using the variance analysis (ANOVA) at a significance level (α) of 0.05, the influence of cement type was statistically confirmed for the liquid limit, optimum moisture content and UCS at 28 and 90 days curing ages.