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Soils with a significant proportion of clay or silt tend to have poor geotechnical characteristics (such as volumetric change and low strength) when exposed to varying moisture contents. The chemical stabilizers currently used are costly and have negative effects on the environment. Arkansas, in the United States, is the leading producer of rice in the country. During rice production, ~20% of the harvested grain consists of rice husk (RH). The rice milling process produces ash with a considerable amount of silicate. Research is being conducted to address the environmental concerns associated with its disposal in Arkansas, as there is growing interest in using rice husk ash (RHA) as a stabilizing additive for problematic soils. For RHA to be effective, an activator such as lime may be needed. The present study focuses on investigating the effectiveness of RHA in stabilizing substandard soils, as no prior study has used RHA as a stabilizing agent in the United States. Additionally, the research aims to determine the optimal proportions of RHA, hydrated lime (HL), or a combination of both. The study employs varying percentages of RHA (3%, 6%, and 9%) and HL (1%, 3%, and 5%) in a unary system. In the binary system, 3%, 4%, and 5% of RHA are combined with 1% HL. The study includes a range of routine tests, such as assessments of Atterberg limits, modified proctor compaction, pH levels, California bearing ratio (CBR), unconfined compressive strength (UCS), and free swell (FS). Furthermore, results from scanning electron microscopy (SEM) coupled with X‐ray diffractometer analyses demonstrated significant improvements in UCS and CBR values for the treated soils, indicating enhanced strength and stability. Moreover, the FS test reveals a reduction in swelling characteristics for the stabilized soils. It was found the optimal dosages of RHA and HL were 6% and 3%, respectively. Notably, when RHA and HL were combined, a blend of these two stabilizing agents exhibited the most promising results in terms of improving the swelling. The optimum percentage of the combined stabilizing agents was 4% RHA + 1% HL. The findings of this proof‐of‐concept research hold substantial potential for the construction industry in Arkansas, offering cost‐effective alternatives to conventional soil stabilization methods while promoting the sustainable and environmentally conscious use of RHA. [ABSTRACT FROM AUTHOR]

Growing concern over the combustion cost and environment has made road engineers and scientists to explore the possible use of locally available materials for the construction of roads. The present study evaluated the strength and durability characteristics of five sites having locally available silty soils using lime and cement–sand stabilization technique. The test results showed that the cement–sand stabilization technique using 6% cement and 5% local sand resulted in higher strength and durability as compared to lime stabilization. There is also a significant increase in the value of the soaked California bearing ratio (CBR). As unconfined compressive strength (UCS) attained the threshold strength as prescribed by IRC SP 72 2015 for the granular sub-base (GSB) layer, by the use of sand cement stabilization, this technique of stabilization for local silty soils could be used for GSB for low volume road (LVR) construction. As observed from microstructural results which were performed by analysing SEM images, sand cement stabilisation leads to CSH gel and agglomerate formation thereby increasing strength and durability properties. The cost analysis for the replaced stabilized GSB layer showed that using sand–cement stabilization, the estimated cost can be reduced by 56% of the total cost as compared to the conventional method. [ABSTRACT FROM AUTHOR]

Nowadays, for soil stabilisation and cleaner production of geo-composites, the possibility of utilizing waste rubber is in vogue. The present paper deals with experimentally investigating the mechanical and micro-structural characteristics of weak Indian clayey soil partially substituted with lime (0–3.5%) and waste rubber tyre powder (0–15%). It was observed that, with increasing lime and rubber powder content, the plasticity index of the soil decreases. The shear strength and compaction testing results reveal that adding lime and rubber tyre powder (RTP) enhances the geotechnical performance of clayey soil up to an optimum dosage value. Also, the tri-axial shear testing was performed to obtain stress-strain curves for all considered soil mixes. For modified clayey soil containing 3% lime and 12.5% rubber powder, the cohesion values and bearing capacities improved phenomenally by 36.1% and 88.6% respectively, when compared to clayey soil. Further for this mix, SEM analysis reveals a compacted microstructure which improves dry-density and California's bearing ratio among all modified mixes. The novel co-relations upon regression analysis are found able to predict plasticity index, dry density, bearing capacity and shear strength with higher confidence levels. Overall, the cost-benefit analysis worked out to obtain the optimum cost of construction of footings and flexible pavement shows cost deductions up to 19% and 39% respectively while utilizing modified clay soil mixes containing 3% lime and 12.5% rubber powder in subgrade, ultimately making production stronger, cheaper and environment friendly. • Experimental investigations on finding synergistic performance of clayey soil, lime and waste rubber tyre powder. • Atterberg's limits, shear, compaction, CBR, & microstructural characteristics shows better performance of modified mixes. • Optimised clay-lime-RTP mix reports 44% and 88.63% improvements in shear strength and bearing capacities respectively. • Decrement in productional cost of up to 39% for modified geo-mixes in road pavement and foundation constructions. [ABSTRACT FROM AUTHOR]