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Expansive soils are extremely susceptible to swelling and shrinkage associated with seasonal changes in their moisture content. This can cause serious damage to structures constructed on expansive soils. Stabilization using additives is widely used to mitigate the concerns of expansive soils by controlling the changes in volume, thereby increasing the strength and durability of the soils. Multistabilizers, including a low percentage of conventional additives with nonconventional additives, can reduce the costs of stabilization. The performance of the stabilized soil can be enhanced by admixture optimization to ascertain that the agent's ratios are quite adequate to meet the optimal levels of modification. Unfortunately, despite the development of advanced techniques for investigating the stabilization of expansive soil, limited studies are devoted to the optimization of admixture to soils. Hence, in this research, an approach based on rough set theory, a mathematical data mining approach, is presented for multiagent optimization for efficient treatment of expansive soils. The multiadditives used in this study are almond shell ash (ASA), volcanic rock dust (VRD), and portland cement (PC). The differential free swell test, the California bearing ratio test, and the unconfined compressive strength test were applied for assessing the characteristics of the stabilized soil specimens. The obtained results and the confirmatory tests demonstrated that a combination of 20% ASA and 20% VRD with 8% PC provides the optimum results in the properties of expansive soil. The microstructural analysis denoted an enhanced modification of the soil engineering properties. The outcomes of this research confirm that the rough set optimization procedure is highly suitable for application in multiagent optimization for the efficient treatment of expansive soils. [ABSTRACT FROM AUTHOR]

Cement stabilization is a soil improvement technique widely adopted for soft soils. The extent of improvement to the physical properties varies largely with soil type and often requires laborious laboratory tests to ascertain such extent of improvement when soil samples from a source are obtained. To offer a quick estimate of the improved unconfined compressive strength of the composite, it is crucial to develop relationships of the strength with essential parameters of the soil. Furthermore, existing studies mainly focused on cement-stabilized clays with minimal granular content. The influence of commonly encountered sand impurities in actual field condition is much less discussed. In view of these limitations, the current study explores the use of activity number (A), liquid limit (wL) and modified apparent void ratio (ec*) as a proxy to unify the strength development of cement-stabilized soft soils used for land reclamation in the modified Abrams's strength predictive model. Incorporation of A and wL is achieved by introducing a new parameter α. Friction due to geometric proximity between sand particles in the composite is represented by ec*. Results show that the proposed model is able to successfully consider the effect of soil properties in the strength development of soils stabilized with Ordinary Portland cement (CEM I) and Portland blast-furnace cement (CEM III/C) and validated with published literature. The proposed models enable quick check of the design when only mix proportions and index properties are available. They also incorporate the influence of sand content, which is merely considered in existing models. [ABSTRACT FROM AUTHOR]

Reinforcing soil with fibers is a useful method for improving the strength and settlement response of soil. The soil and fiber characteristics and their interaction are some of the major factors affecting the strength of reinforced soil. The fibers are usually randomly distributed in the soil, and their orientation has a significant effect on the behavior of the reinforced soil. In the paper, a study of the effect of anisotropic distribution of fibers on the stress-strain response is presented. Based on the concept of the modified Cam clay model, an analytical model was formulated for the fiber-reinforced soil, and the effect of fiber orientation on the stress-strain behavior of soil was studied in detail. The results show that, as the inclination of fibers with the horizontal plane increased, the contribution of fibers in improving the strength of fiber-reinforced soil decreased. The effect of fibers is maximum when they are in the direction of extension, and vice versa. [ABSTRACT FROM AUTHOR]