Effect of Selected Nanospheres on the Mechanical Strength of Lime-Stabilized High-Plasticity Clay Soils

Abstract

The proper design of protective structures may start from improving the characteristics of soils. In order to obtain reasonable safety criteria, several research studies have recently been dedicated to enhancing complex civil engineering structural systems with the use of nanotechnology. Thus, the following paper investigates the effect of nanospheres, including nanosilica (nano-SiO2) and nano zinc oxide (nano-ZnO), on lime-stabilized high-plasticity clay soil. For this purpose, unconfined compressive strength (UCS) and California bearing ratio (CBR) tests were performed on samples. The results showed that the use of the selected nanospheres greatly increased the UCS of the samples compared to untreated soil. The UCS value of samples containing 6% lime and 1.5% nano-ZnO after 28 days of treatment increased by 5-fold compared to the UCS of untreated samples. In addition, the samples containing 6% lime and 2% nano-SiO2, with similar curing conditions, experienced a 5.3-fold increase in their UCS value compared to the untreated samples. These compounds were considered as the optimal amounts and showed the highest mechanical strength in both UCS and CBR tests. The same trend was achieved in the CBR test, in which the CBR value for the optimal mixtures containing nano-ZnO and nano-SiO2 was 14.8 and 16.6 times higher than that of high-plasticity clay soil, respectively. Finally, the results obtained from scanning electron microscopy (SEM) analysis revealed that the nanospheres caused a dense and compact matrix to form in the soil, which led to the enhancement of the mechanical strength of the treated samples.

Development and Field Application of Phosphogypsum-Based Soil Subgrade Stabilizers

“…Silty soil from northern Jiangsu, China was used in the current study. The construction standards of a normal roadbed indicate that soil to be used should be mixed with that of solidified material under an optimal moisture content [28]. Prior to stabilization, the chemical composition of the silty soil was determined via X-ray fluorescence spectrometry.…”

Micro to Nanolevel Stabilization of Expansive Clay Using Agro-Wastes

“…Expansive clay subgrade of low bearing capacity is considered as a costly issue [14] for which stabilization is a feasible solution to increase shear strength and to decrease water susceptibility [15]. Furthermore, the expansive clays as subgrade are prone to large settlements resulting in formation of uneven geometry around the embankment [16][17][18]. From geotechnical perspectives in pavements subgrades built with expansive clays, commonly the more important parameters of interest are resilient modulus (MR), elastic modulus (Es), unconfned compressive strength (UCT), and California bearing ratio (CBR) index.…”

“…Te main drawback of cement and lime stabilization is the emission of harmful gases such as CO 2 , SO 2 , and NO x in the environment which outweighs their benefcial efects [25][26][27]. Tese microstabilizers increase the pH of expansive clay up to 12 which creates environmental problems [17]. Fly ash (a coal combustion product) due to its high value of the pH reduces the nutrient access to plants when mixed with expansive clays, so the adoption of green additives for stabilization is trending amongst geotechnical and pavement engineers [28][29][30].…”

Study on Soil-Water Characteristics of Expansive Soil under the Dry-Wet Cycle and Freeze-Thaw Cycle considering Volumetric Strain

“…At present, in addition to the research on deformation and strength [6,7] and solidification improvement [8][9][10] of expansive soil, some achievements have been made in the aspect of the soil-water characteristics [11,12]. Ito and Azam [13] pointed out the swell-shrink path is S-shaped and indicated that it is more accurate to express SWCC by gravimetric water content than by saturation.…”