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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]

Constructing on soft clay entails engineering challenges, such as significant volumetric changes; hence, stabilizing such problematic soil is essential. Since using lime in stabilizing soil is not recommended in some regions (e.g., Manitoba, Canada) due to some environmental concerns, there is a pressing need to explore suitable alternatives. This study investigates the efficiency of stabilizing soft clay using nano-modified cementitious binders (cement, slag, and nano-silica), reinforced with a new class of fibers (basalt fiber pellets). The mechanical and durability properties of the mixtures have been tested in terms of California bearing ratio, unconsolidated–undrained triaxial stresses, and freezing–thawing resistance. Thermogravimetry and scanning electron microscope analyses were performed to interpret the bulk trends. The results showed significant improvement for soft clay specimens stabilized with the nano-modified cementitious binders and reinforced with the pellets. This demonstrates the potential of the proposed reinforced binders for field applications involving the stabilization of soft soils. [ABSTRACT FROM AUTHOR]

Australian design practice for granular pavements with lime-modified subgrades is very conservative and does not consider the initial and long-term strength improvement. It recommends that the assigned California bearing ratio (CBR) of a modified subgrade soil should not exceed 15% for most roads. Two types of clay soils with plasticity indices of 22% and 42.5% were treated herein with their minimum lime demand (MLD) and tested to evaluate the modification influence on their properties. These properties include pH, compaction, compressive strength, bearing capacity, resilient modulus, and permanent deformation. Three different mellowing periods, 24, 48, and 72 h, between lime treatment and compaction, were used in this study to identify their optimum mellowing periods. Analysis of testing results for long-term compressive strength and CBR showed that MLD improves both soils' compressive strength and bearing capacity. Using the actual CBR values of lime-treated soils in designing the cover over subgrade results in a 30% reduction in pavement thickness. Lime modification of these soils also improves their resilient moduli and permanent deformation. The best results are achieved with mellowing periods of 24 h for Soil A and 72 h for Soil B. These optimum mellowing periods reduced permanent deformation of Soil A to less than 0.15% and 0.11% for Soil A. Considering the study findings, it is believed that thinner pavements can be designed and built on modified subgrades with MLD, which will help road agencies save funds. [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]

The expansive soils have always presented various challenges for geotechnical and civil engineers due to their low bearing capacity and high swell-shrinkage characteristics. This study aims to utilize liming leather waste ash (LLWA) as a sole expansive soil stabilizer examining its effects on various engineering properties of soil such as consistency limits, compaction parameters, unconfined compressive strength (UCS), California bearing ratio (CBR), and swell parameters. The observations are also made on the curing effects on the strength parameters of the soil-additive mix. It was observed that the LLWA contains cementitious characteristics of lime and silica combined and can substantially reduce the plasticity and swell-shrink behavior of the soil and improve its strength and bearing characteristics. The UCS and CBR values have also shown multifold increase post curing with UCS and soaked CBR escalating by 278% and 387% respectively. The test results are further explained through the microstructure study which confirms the mineralogical transformation and cementation of soil particles. A one-dimensional rainfall-simulated leachate study has been carried out over a pavement model at the end to access the possible impact of ash treatment on the water table. [ABSTRACT FROM AUTHOR]