Search

This paper examines the effectiveness of using varying proportion (2%, 4% and 6% by dry weight of soil) of a newly formulated biomass silica soil stabiliser (BSS) on tropical lateritic clay which has deleterious effects on construction materials due to its high amounts of SiO2 and Fe2O3. A series of laboratory experiment testing methods: i.e. particle size distribution, Atterberg Limits, linear shrinkage, pH value, compaction, California Bearing Ratio, unconfined compression test, and cyclic load triaxial test were conducted in accordance to BS1377:1990 and AASHTO T307–99:2003 to examine the geotechnical properties of the BSS structured lateritic clay subjected to 0, 7, 14 and 28 curing days. Physicochemical tests such as X-ray fluorescence (XRF), X-ray diffraction (XRD) and field-emission scanning electron microscope (FESEM) were conducted to further support the mineralogical composition and microstructure evidence of the structured soil and substantiate the interpretation of the mechanical strength data. The test results reveal that the notable changes in the properties and behavior of structured lateritic clay was governed by the BSS proportion and curing period. There is an immediate enhancement in the geotechnical properties of the 2% BSS structured lateritic clay, altering soil type from CH to MH before curing begin. The unconfined compressive test results indicate a distinct effectiveness in stabilizing lateritic clay, from 400 kPa to 3675 kPa for 6% BSS structured lateritic clay cured to 28 days. Both soaked and unsoaked California Bearing Ratio (CBR) values were 12.4 and 5.8 folds higher than that of the virgin lateritic clay. The cyclic load triaxial test reveals that the resilient modulus, MR of the structured soil was significantly increased. For full-scale applications, the association between the mechanical properties and linear shrinkage test results deduce that the optimum proportion of BSS required for an effective stabilisation performance is 6%. Finally, the mechanisms of the microstructural changes in the stabilisation process were mainly attributed to the agglomeration and aggregation of the cemented particle through composition of calcium silicate hydrate cementitious products evidenced in the physicochemical tests.

Loess is a typical collapsible soil, which is widely distributed in the upper and middle areas around the Yellow River of China. The stabilization of loess with lime provides a significant improvement in the physical and the mechanical characteristics of the loess and is therefore widely used in the pavement base and subgrade. Therefore, a systematic investigation of Mohr-Coulomb failure envelope of lime stabilized loess needs to be conducted. In this pursuit, the present research envisages the investigation of the effects of the lime content, porosity and curing time on the strength parameters (friction angle (&phi, ) and cohesion (c)), using a series of triaxial tests performed on lime stabilized loess specimens. The experimental results revealed that the friction angle (&phi, ) was independent of the lime content, the porosity and the curing time of the specimen for a given lime stabilized loess, while the factors mentioned above had a significant effect on the cohesion (c) of the lime stabilized loess. For a relatively short curing time (7 days), the change in the lime content did not present an obvious effect on the cohesion (c) of the stabilized loess. However, when the curing time (28, 90 and 180 days) was longer, the increase of the lime content significantly enhanced the cohesion of the stabilized loess. When the lime content was constant, the cohesion (c) of the stabilized loess increased linearly with the decrease in the void ratio. A power function equation was proposed to assess the comprehensive influences of the factors like the lime content, porosity and curing time on cohesion (c). Finally, the Mohr-Coulomb failure envelopes were drawn based on the triaxial test for 47 specimens with various curing time and confining pressure, and the shear strength parameters obtained by the proposed equation were also compared with the experimental results.

This study aimed to investigate the feasibility of using lime&ndash, slag stabilized loess as base-course material by assessing its unconfined compressive strength (UCS). Loess stabilized with various mix ratios were compacted and cured to three, five, seven, and 28 days, respectively, for further strength tests. The effects of binder content, lime-to-slag (L/S) ratio, porosity, and curing time on the UCS of stabilized loess were addressed in detail. The test results show that UCS increases with the increase in binder content or curing time, and it gains strength rapidly within the first seven days of curing. At the same binder content, UCS decreases with the decrease in L/S ratio or porosity. Finally, the correlations of UCS with binder content, porosity, and curing time were derived, which exhibited reasonable correlation coefficients R2 (from 0.86 to 0.97).