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Artificial cementation of granular soils results in improved stabilization, increased stiffness, and greater mechanical strength. The porosity index and volumetric cement content η / C i v a is presented as a key measure to study the evolution of different soil stabilization types. However, this index had not been previously studied or adjusted for sands in Colombia. Therefore, this study evaluates the applicability of the η / C i v a index on unconfined compressive strength (q u ) and stiffness ( G o ), complemented by microstructural analysis, in four sandy soils from Luruaco (Atlántico), Lorica (Córdoba), Medellín (Antioquia), and Bogotá D.C. The soils were stabilized with Type III Portland cement in dosages of 3%, 5%, 7%, and 9%, and subjected to UCS, ultrasound, and SEM-EDS tests after a curing period of 7 days. It was found that increasing cement content results in higher q u values for the samples, and higher molding density also leads to higher q u values. Additionally, the grain size distribution influenced the adjustment of parameter "a". In the sands from Bogotá and Lorica, with high uniformity, the value of "a" was 1.00. In contrast, mineralogy and particle shape played a predominant role in the sands from Medellín and Luruaco, where the coefficient of uniformity is higher, suggesting a possible inverse relationship between particle angularity and the value of "a". [ABSTRACT FROM AUTHOR]

For almost a decade, various studies have been carried out to prove the suitability of nano additives in enhancing the geotechnical properties of soil. Yet, this line of research is still in its elementary stage, restricting itself to laboratory tests to determine soil's index and engineering properties blended with varying dosages of nano additives. In other words, research on practical applications of nano additives for soil stabilization is scarce. The present work attempts to investigate the suitability of three different nanomaterials as a load-bearing stratum for shallow foundations. The nano additives were chosen in such a way that each of them is from a different origin. One of them is nano calcium carbonate (inorganic) whereas the other two are nano-sized varieties of natural biopolymers, namely nano chitosan (crustacean-based) and nano carboxymethyl cellulose (plant-based). A series of laboratory tests were initially conducted to determine the strength of all three nano-additive-treated soils at different dosages, which were investigated for 180 days to ensure their long-term performance. This was followed by a foundation model study on untreated soil and on soil treated with optimal dosages of nano additives. The results were validated using finite element software followed by a parametric study to optimize the depth of soil stabilization. It was observed that all three nano additives exhibited a better performance when the top layer had the optimal dosage and the subsequent layers had a relatively lesser dosage. [ABSTRACT FROM AUTHOR]

This article focuses on the search for efficient solutions to enhance the mechanical strength of geomaterials, especially soils, with crucial applications in civil engineering. Four promising materials are explored as soil improvement agents: natural latex (rubber trees), lignosulfonate (paper industry byproduct), xanthan gum (bacterial fermentation), and eggshell lime. While other sustainable options exist, these four were chosen for their distinct characteristics and potential for further study. Natural latex, derived from rubber trees, demonstrates exceptional potential for strengthening the mechanical resistance of soils, offering a path to effective stabilization without compromising environmental sustainability. Lignosulfonate, a paper industry byproduct, emerges as an alternative that can significantly enhance the load-bearing capacity of soils, boosting its applicability in civil engineering projects. Xanthan gum, produced through bacterial fermentation, possesses unique properties that increase soil cohesion and strength, making it a valuable option for geotechnical applications. Finally, despite potential challenges, eggshell lime shows promising potential in enhancing the mechanical resistance of soils. This study highlights the importance of evaluating and comparing these agents in terms of their effectiveness in improving the mechanical strength of soils in civil engineering applications. In the literature review, the impact of stabilizer addition (%) was examined for the four cementing agents studied, along with its influence on key soil properties like optimum moisture content (OMC, %), maximum dry density (MDD, gm/cc), California bearing ratio (CBR, %), uniaxial compressive strength (UCS) at 28 days (MPa), and the change in UCS (ΔUCS, %) among other physicochemical parameters. Appropriate selection of these materials can lead to developing more robust and sustainable geomaterials, promoting significant advancements in geotechnical engineering and civil construction practices. To evaluate their effectiveness, the efficiency of one of them was assessed experimentally. Xanthan gum (XG) was selected to biopolymerize clay soil. Specimens were prepared for strength and stiffness tests, including unconfined compression, scanning electron microscopy (SEM), and ultrasonic wave analysis. The impact of stabilizer concentration was examined (e.g., 1%, 3%, 5% xanthan gum) to assess how dosage affects the soil–stabilizer mixture. The results showed that the rubber increases the unconfined compression and stiffness of the soil, controlled by the XG's porosity/volumetric quantity ratio. The research demonstrates the potential of XG, but a broader analysis of all four materials with the outlined testing methods paves the way for future advancements in geotechnical engineering. [ABSTRACT FROM AUTHOR]

One of the most effective and economical means to enhance weak clay is to treat it using cement combined with fibres. As such, this study investigates the strength and stiffness performance and durability of Portland-cement-stabilised carbon-fibre-reinforced alluvium clay. The proposed blend was investigated through unconfined compressive strength, elastic modulus, initial shear modulus, and accumulated loss of mass. The results of this study suggest that the addition of cement and carbon fibre improved the strength and durability of the samples. The dosage of 0.4% carbon fibre (by dry mass of clay) proved to be most effective when reinforcing the specimens. The blend with 7% cement (by dry mass of clay) showed more than 50% increase in strength and stiffness and around 50% reduction in the accumulated loss of mass with the inclusion of 0.4% of fibre. Moreover, this study proposes unique power functions that can predict composite parameters on the basis of the novel porosity-binder index. In addition, the study provides an equation that correlates all of the properties with each other, thus enabling estimation of required property through merely one type of test. [ABSTRACT FROM AUTHOR]

The environment is seriously being affected by the leachate release at the unconstructed and badly constructed waste containment or landfill facilities around the globe. The worst hit is the developing world where there is little or totally no waste management system and facilities to receive waste released into the atmosphere. This research work is focused on the leachate drain into the soil and the underground water from landfills, which toxicifies both the soil and the water. Also, the construction of the liner or barrier with cement poses serious threat to the environment due to oxides of carbon release and this research also took this into account by replacing the utilization of cement with rice husk ash (RHA), which has proven to have the potentials of replacing cement as a supplementary binder. Laboratory tests were conducted to determine the hydraulic conductivity (K) of lateritic soil (LS) ameliorated with different dosages of RHA. Other hydromechanical properties of the treated blend were studied and multiple data were generated for the artificial neural network (ANN) back-propagation (-BP), genetic algorithm (GA) and gradual reducing gradient (GRG), genetic programming (GP) and evolutionary polynomial regression (EPR) prediction exercises. Results show that the LS was a poorly graded A-2 sandy silt soil, which was subjected to three different compaction energies with the minimum of the British standard light (BSL) and derived k of 6.95E-10, 50.75E-10 and 32.33E-10 for BSL, west African standard and British standard heavy, respectively. The RHA addition improved the studied properties of the ameliorated LS. Out of the five models, the ANN-GRG outclassed others with a performance of 99% with minimal error compared with the rest. Potentially, this research has shown that RHA with a pozzolanic chemical moduli of 81.47% can replace cement in the construction of ecofriendly and more efficient landfills and waste containemnt barriers to save the soil and the underground water as well as the environment from leachate contamination and carbon emissions. [ABSTRACT FROM AUTHOR]

This paper presents the elaboration of equations controlling the unconfined compression strength (qu) of a silty soil treated with three types of cement. The equations were created under influence of the ratio between porosity and volumetric cement content (η/Civ), also called voids/cement ratio, and it was also possible to measure cement content and the influence of water/cement ratio. Results demonstrate the following: (i) addition of cement increases linearly the strength of soil-cement mixture; (ii) qu increases with increase in the molding dry unit weight (γd); (iii) qu increases with decrease in porosity; and (iv) decrease in η/Civ ratio causes increase in qu. Three general equations of qu estimate were developed for each type of cement with a 28-day curing period, and a normalized general equation was proposed with the three types of cement. Equations demonstrate that it is possible to estimate qu of the treated soil within γd range, cement amount and curing period employed in this work. [ABSTRACT FROM AUTHOR]