Appropriate Use of Lime in the Study of the Physicochemical Behaviour of Stabilised Lateritic Soil under Continuous Water Ingress

Abstract

Lime stabilisation is one of the traditional methods of improving the engineering properties of lateritic soils for use as subgrade and foundation materials for the construction of road pavements and highway embankments. Understanding the mechanical performance of lime-stabilised lateritic subgrades in terms of their durability under continuous water ingress will improve environmental sustainability by conserving scarce natural resources and reducing the environmental impacts of repair and replacement of pavements. However, there are several conflicting reports on the durability of lime-stabilised soils subjected to continuous water ingress and harsh environmental conditions. Therefore, this paper evaluates the influence of leaching on the physicochemical behaviour and durability of lime-stabilised lateritic soil under continuous water ingress, simulating the typical experience in a tropical environment. Variations in the strength and durability of the lateritic soil at various lime contents (0, 2.5, 5, 7.5, 10, 15, and 20 wt.%) and soaking periods (3, 7, 14 and 28 days) were evaluated by performing the California bearing ratio tests before and after subjecting the lime-lateritic soil (LLS) samples to continuous leaching using two modified leaching cells. Furthermore, physicochemical analysis was performed to assess the variation of cation concentrations and changes in the physical properties of the pore fluid as the leaching time progressed from 3 to 28 days. The results show that the minimum strength reduction index of the soil corresponds to its lime stabilisation optimum (LSO). Electrical conductivity decreased monotonically and almost uniformly with an increase in leaching time, irrespective of lime content. So, too, was calcium concentration and to a lesser degree for pH and potassium concentration. Adverse changes in the physicochemical behaviour of the LLS samples occurred at lime contents below and slightly above the optimum lime content of the soil. Whereas permanent pozzolanic reactions occurred at lime contents above the LSO and thus resulted in a 45-fold increase in strength and durability. The results are significant for reducing the detrimental effect of the leaching-induced deterioration of flexible pavements founded on tropical floodplains.

Hydraulic and Swell–Shrink Characteristics of Clay and Recycled Zeolite Mixtures for Liner Construction in Sustainable Waste Landfill

“…As is visible in Table 3 and Figure 4, addition of 10% by mass zeolite to clayey specimens increased value of liquid and plastic limits and in some cases, as a result, reduced the plasticity index. Similar results were observed by Okeke et al [25] for lateritic soils stabilized by various percentages of lime addition. The basic characteristics of the sampled clayey soils are presented in Table 2, while the determined Atterberg limits for all tested materials and reference samples are presented in Table 3.…”

“…As is visible in Table 3 and Figure 4, addition of 10% by mass zeolite to clayey specimens increased value of liquid and plastic limits and in some cases, as a result, reduced the plasticity index. Similar results were observed by Okeke et al [25] for lateritic soils stabilized by various percentages of lime addition. 5.81 × 10 −10 ± 9.9 × 10 −11 * (K + Ch) and (I + S) mean (kaolinite and chlorites) and (illites and smectities).…”

“…The samples prepared for molding gravimetric water content determination are also presented in Figure 2. Distilled water was used as a permeating liquid, based on numerous studies concerning applicability of various mineral materials for compacted liner construction [18,20,22,[24][25][26][27]29,[32][33][34]. The obtained values of saturated hydraulic conductivity coefficients were subjected to the standard statistical procedures including Shapiro-Wilk normality tests and comparison of two dependent variables (Ks for clay-zeolite mixtures and reference samples) by nonparametric Wilcoxon test (due to observed distributions being different than normal).…”

“…However, in some cases, the local clay substrates may not allow reaching the required values of K s in the full range of molding water contents [24] or for the selected values of initial water content, usually after compaction dry from optimum (dry side of the Proctor curve) [18,20]. However, the insufficient sealing capabilities of some locally available earthen materials may be improved by addition of the available, sustainable, and recycled fine particles specimens such as various types of zeolites, silica fume, lime [25], bentonites, fly ash, coal gangue [26], construction and demolition waste, activated carbon, shale [27], olivine [28], organoclays, etc. allowing a significant decrease in permeability of the compacted clay liners [22,[29][30][31][32][33][34].…”

Microstructure and Physical-Mechanical Characteristics of Treated Kaolin-Bentonite Mixture for Application in Compacted Liner Systems

“…It is proposed in this study that minimal treatment of highly expansive clays can aid a reduction in hydrated void ratio at low suction as well as enhance the moisture retention capacity of these clays, hence minimising cracking during desaturation. Although, the general mechanical and hydraulic performances of chemically treated expansive clays used in lining systems have been investigated in several research works [19][20][21][22][23][24][25][26][27], studies devoted to the moisture retention behaviour of these stabilised systems are rare. Consequently, this research aims to study the mechanical behaviour as well as provide an understanding of moisture retention properties of medium-to-highly expansive clays treated with cement.…”