Abstract
During any construction on soil surface such as construction of road and airport pavements, compaction of the soil is required and soil stabilization plays a vital role. Various ...characteristics of soil should be optimized with different factors. Expansive soil has property of swelling when moisture content increases and shrinking when water gets evaporated. Rice husk is a major agricultural waste that is easily available in in India and is generally burnt to get rice husk ash (RHA). This study has been aimed to get dual benefit, first to stabilize expansive soil by addition of RHA and second to effectively utilize RHA, the agricultural waste. It has been observed that at 12% RHA in presence of 5% cement can be effectively used to improve plasticity of soil and CBR value resulting in effective soil stabilization. Thus, the research demonstrates that agricultural waste has efficient use in soil stabilization.
One of the mass prompt practices of soils is for engineering projects such as the construction of roads, buildings, dams, and so on. Therefore, suitability of index and mechanical properties needs to ...be investigated. This study aims to determine the essential quality material required for road construction, thereby poses détente prospect for the disposal of ineffectual atrophy generated on sites. Such materials are classified into index and mechanical properties. Six subgrade samples were taken at the depth to bottom ranging from (1.0-5.0) m and tested. The sample was subdued to the laboratory tests, such as Sieve Analysis, Atterberg limits, compaction, California Bearing Ratio (CBR), and Specific Gravity (SG) respectively. The mechanical analysis which involved particle size distribution revealed that the subgrade was finely grated with a limit of ≤35% for subgrade passing sieve No. 200 (0.075 mm) with 29.1%, with an average Natural Moist Content (NMC) of 13.9%. The Maximum Dry Density (MDD) and Optimum Moisture Content (OMC) were 1.83 mg/m3 and 11.5%. The index analysis involved the liquid and plastic limits determination of Liquid Limit (LL) of 35.8%, Plastic Limit (PL) of 24.0%, and a Plasticity Index (PI) of 12%. California Bearing Ratio (CBR) results were 20.3% (soaked). The SG test results ranged from (2.68-2.94) kg/m3, employing the American Association of State Highway and Transport Officials (AASHTO) system of soil classification. The AASHTO grouped the materials into A-1, subgroups A-1-b and A-2-4 constituting 50% and 29.1%, with significant materials composed of stone fragments and sand rating the subgrade samples as excellent to good materials suitable for road construction.
•IR spectra of kaolinite and montmorillonite at different moistures are measured.•Formation of H2O layers on clay particles surfaces in mixtures of minerals is studied.•Hydration of clay particles at ...low moistures has non-linear nature.•Correlation of plastic properties and the IR spectra of clay particles is discovered.
KGa-1b kaolinite and STx-1b montmorillonite, as well as their mechanical mixture in 1:1 mass ratio, have been experimentally investigated by total reflection IR spectroscopy (IR-ATR) at different moisture modes. The aim of this research was to investigate the spectral features during the formation of water films on the surface of individual minerals, and in mixtures. The analysis of mineral composition of the wetted samples has been carried out by decomposing the experimental spectra into the linear combination of basic spectra of H2O and the minerals used. The obtained dependences of the decomposition coefficients on moisture allow studying the peculiarities of the formation of a water layer on mineral particles, studying the dynamics of moisture redistribution between mineral particles in mixtures, and evaluating the plastic characteristics of clays.
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•The incorporation of RA can reduce the OMC and MDD of high liquid limit clay.•The UCS and the cohesion of the treated clay peaks at the RA content of 15%.•The increase of concrete-to-brick ratio can ...increase the UCS and the internal angle of the treated clay.•The increasing RA content and concrete-to-brick ratio result in larger CBR values and better immersion stability.•Recycled aggregate can promote the formation of agglomerates and increase stability.
High liquid limit soil has low strength and poor immersion stability, which may cause engineering problems when used as embankment filling. In this paper, recycled concrete aggregate (RCA) and recycled brick aggregate (RCB) were used to improve the mechanical strength and immersion stability of high liquid limit clay. A series of laboratory tests including compaction tests, unconfined compression strength (UCS) test, direct shear test, California bearing ratio (CBR) test and Scanning electron microscope (SEM) test was carried out to study the evolution of mechanical properties of treated soil. The test results show that the addition of recycled aggregate (RA) would reduce the optimum water content (OWC) and maximum dry density (MDD) of high liquid limit clay. With the increase of the content of RA, the UCS of the treated soil generally increases first and then decreases. The longer the curing age, the greater the UCS. Mixing RA with high liquid limit clay will increase the stability and shear strength of high liquid limit clay. With the increase of RA content, the internal friction angle of the treated soil gradually increases; the cohesion first increases and then decreases. Compared with the untreated high liquid limit clay, the bearing capacity and immersion stability of the treated soil have been significantly treated, and with higher content of RCA, the bearing capacity and immersion stability of the treated soil trend to be stronger. SEM images show that the incorporation of RA can promote the formation of agglomerates to increase the integrity. The results of this experimental study can provide reference value for actual engineering.
•Workability of sand-bentonite-cement is studied for two-phase cut-off wall.•Cement causes significant increase in flowability and bleeding.•Quick cement–water-bentonite reactions are responsible for ...workability change.•Results from one-phase construction are not applicable directly for two-phase.
The workability of fresh materials is critical for sand-bentonite-cement cut-off wall; however, previous studies are limited to the one-phase construction method, not the two-phase. Hence, this study attempts to fill the gap. First, series of flowability and bleeding tests on sand-bentonite mixtures were conducted (1st phase); subsequently, cement slurry was added to mixtures (2nd phase) to investigate its effect on the workability. The results indicated that, for sand-bentonite mixtures with required workability for 1st phase of construction, the addition of cement caused significant increase in flowability and bleeding, i.e. reducing the workability for 2nd phase, especially for sodium bentonite. The reason was revealed as the short-term interactions (mainly cation exchange) between bentonite and cement hydration products, reducing water retention capacity and swelling potential of bentonite.
Abstract
The production of sugarcane bagasse ash (SBA), glass fiber (GF) and ceramic dust (CD) in developing countries at very large scale usually poses a severe disposal problem. The purpose of this ...research is to determine whether these three waste products are suitable for improving the engineering characteristics of expanding soil. The study has been carried out by varying the content of SBA (0-20%), CD (0-20%) and GF (0-4%) in black cotton soil. Optimization was carried out to find out the composition of the ideal quaternary blend. The use of these materials was found to decrease the maximum dry density and swelling of soil with increase in optimum moisture content. In addition, the liquid limit was found to decline with increment in CBR and unconfined compressive strength. The study confirms the use of these waste materials as soil stabilizers in addition to provide a solution for waste reuse.
Among the multitude of alternate plasticity index (PI) estimation proposals, empirical correlations based on the linear shrinkage (LS) test, originally proposed in the 1967 edition of the British BS ...1377 standard, seem to be gaining increased attention. This study has two main aims: (i) re-examining LS-based correlations for PI estimation to better understand their true potentials and/or limitations; and (ii) investigating the possibility of employing LS, as a proxy for the standard PI, for fine-grained soil classification. To this end, comprehensive statistical analyses were performed on the largest and most diverse database assembled of its kind, entailing PI:LS measurements for 265 different fine-grained soils pertaining to the ‘soft’ base percussion-cup liquid limit (LL = 17–134%) and the Australian standard LS = 0.5–32.0%. It was demonstrated that the LS can generally only provide a rough approximation of the actual PI. At best, only those predictions produced by PI = 1.86 × LS for low-plasticity soils (i.e., LL ≤ 35%) included in the database may be deemed acceptable, specifically when difficulties are encountered in executing the standard plastic limit (PL) thread-rolling test for such soils. The second/novel aim of this study found that the agreement level between the Casagrande-style plasticity-chart classification (based on the measured PI = LL − PL) and that performed using the PI deduced from a newly introduced multivariable correlation involving LS and LL, as inputs, was obtained as 95%. Hence, in the absence of measured PI, the multivariable PI:LS:LL correlation may be deemed suitable for preliminary soil classification purposes.
•Examine linear shrinkage (LS) – liquid limit (LL) correlations for plasticity index (PI) estimates.•Statistical analysis of large PI:LS database for 265 different fine-grained soils with measured PL.•LS can generally only provide guesstimate of actual PI = LL − thread-rolling plastic limit (PL).•For low-plasticity soils (i.e., LL ≤ 35%), predictions by PI = 1.86 × LS may be deemed acceptable.•New multivariable PI:LS:LL correlation deemed suitable for preliminary soil classification purposes.
The Authors have presented an interesting paper (Hrubesova et al., 2020), which aims (in part) to validate the Moharjerani (1999) calibration approach for establishing the 80 g/30° fall-cone ...penetration depth equating to the liquid limit by the Casagrande percussion-cup approach, determined according to the British Standard. In this paper, the Discussers present some clarifications on, and state various observations regarding, the approaches adopted in the Hrubesova et al. (2020) investigation, as well as the Moharjerani (1999) calibration approach employed therein. The Discussers also present a description of some relevant literature not covered in the Authors' paper (Hrubesova et al. 2020) aimed at making further clarifications on this important area of geotechnical practice.
•In present global context, percussion-cup and fall-cone generally considered equally valid for liquid limit (LL) determination•Fall cone (FC) approach generally has superior repeatability and reproducibility•Recommended to consistently redefine LL uniquely as water content at which universal FC penetrates specified depth into remoulded specimen•Plastic limit (plastic/brittle boundary) condition uniquely established using standard thread-rolling method•Any agreement between water contents of plastic limit (PL) and PL100 for a given fine-grained soil essentially coincidental
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