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Go to Editorial ManagerPlastic concrete is widely used in hydraulic cut-off walls of earth and rockfill dams because of its low permeability, high deformability, and good workability. The addition of bentonite clay is also among the primary factors that can influence its performance as it greatly decreases the hydraulic conductivity. Mechanical performance and crack resistance are enhanced by the fiber reinforcement of polypropylene (PP) and steel fibers. This paper investigated the interaction of calcium bentonite dosage, fiber type and content, cement content, and water-to-binder ratio (W/(C +B)) on the flowability, compressive strength, and permeability of 29 plastic concrete mixtures to be used in cut-off wall construction. The experimental tests were performed in accordance with ASTM D6103 on flowability, ASTM C39 on compressive strength and BS EN 12390-8:2019 on permeability. The findings revealed that the best mixtures had a flowability of over 14 cm, compressive strength of 1.23 to 25.78 MPa and permeability coefficients of 10⁻⁹ to 10⁻⁷ cm/s. Adding more bentonite was a very effective way of decreasing permeability, but frequently had adverse effects on compressive strength and workability. Polypropylene fibers showed a more favorable contribution to crack resistance and workability compared to steel fiber. The findings indicate that close fine-tuning of the water to binder ratio (W/(C+B)) as well as dosages of superplasticizer is essential in attaining balanced performance. The study presents a guideline to enhance durable, non-pervious, plastic concrete that can be used in hydraulic works and prepares the groundwork in future investigations of long-term durability and chemical integrity.
This study examined the efficacy of Fly Ash Type F-based geopolymer binders in enhancing the impermeability of clayey soils. A clayey soil of the CL type was stabilized using geopolymer mixtures composed of fly ash activated by two different alkaline systems: (1) sodium silicate combined with lime and (2) sodium bicarbonate combined with lime. The FA binders were added at dosages of 10%, 20%, and 30% by weight of dry soil, and FA/AA was 0.2, 0.4, and 0.6. Standard falling head permeability tests were performed to evaluate the efficacy of the therapies. The experimen results indicated a marked improvement in reducing soil permeability with both alkaline activator systems. The greatest reduction was observed at a 30% replacement ratio when the sodium silicate–lime mixture was used. Beyond this level, a slight increase in permeability was recorded, which can be attributed to the excessive alkalinity of the mixture and the potential formation of microcracks. On the other hand, the sodium bicarbonate–lime system showed a consistent trend, where higher replacement levels continued to lower permeability. Overall, the study highlights that fly ash–based geopolymers, when properly optimized in terms of activator type and dosage, provide an effective and sustainable approach for improving the impermeability of clayey soils, particularly in hydraulic and geotechnical engineering applications
ABSTRACT A study of the effect of cutback MC-60 on the permeability and compressibility characteristics of sandy gypseous soil is presented. Series of laboratory tests are carried out including classification, compaction, and conventional oedometer tests as well as a new test named compressibility- permeability leaching test. Test results shows that the superlative enhancement in compressibility and permeability and thereby in collapsibility occurred with 7% additive.
A BSTRACT: Leaching effects on permeability and compressibility characteristics of undisturbed sandy gypseous soil were investigated in this study. Time, stress level, strain, leachate condition and flow velocity were considered. The loading, leaching and permeability measurements were carried out utilizing the constant head pereameter with special modifications. Test results show that salt leaching and thereby leaching strain is a time dependent process. Also as leaching strain continued coefficient of permeability decreases.
The earth-fill dams are simple structures which are able to prevent the sliding and overturning because of their self-weight. Due to lack of suitable clay materials, the dams may be designed as zoned core which is composed of three vertical zones contains central impermeable core and two permeable shells on their two sides of the core. Impervious core is used in zoned earth dam to reduce the quantity of seepage through the body of the dam and to relief part of risk of piping and erosion in the downstream side. This study aims to study the soil properties that is used as a core of earth dam through a series of laboratory experiments that were carried out a several soil samples mixed with both lime and silica fume, in order to stabilize the soil. The process of stabilization aims to increase the soil strength and reducing its permeability and compressibility. Test results show that adding lime and silica fume to the soil decreases the permeability of soil with different cases of study, the percentage of decreases in case of standard compaction about (21%-90%) while in modified compaction test the permeability decreases in range (41.7%-91.3%). Also the unconfined compressive strength of the soil increasing significantly in both cases of compaction which were standard and modified. When add the materials, these values were increased in range (76%-90%) for samples from standard compaction test, while it being (0.21%-42%) in modified compaction test.
Organic soils are problematic soil for various engineering applications due to their high compressibility and low shear strength which need to be improved. For many soil improvement techniques, using waste materials, such as fly ash (FA), is a practical and sustainable process. In this research, FA and geopolymer were used e used to reduce organic soil's compressibility. A one-dimensional consolidation test was performed to evaluate the organic soil's consolidation and compressibility properties. The geopolymer was prepared using 20% FA and of sodium hydroxide ratio and sodium silicate alkali solutions. The geopolymer specimens were first cured for 2 hours at 45 and 65 oC, then cured for further 28 days at room temperature. The consolidation test results showed that FA-based geopolymer is effective in stabilizing organic soils due to the observed improvement in the compressibility, consolidation, and permeability characteristics. The compression index decreased by 98.16%, and the permeability decreased by 95%.
The study included evaluating water ten wells in the area Dabaa within the western region of Iraq for agricultural use, as has been the study of water quality of these wells during the year by conducting a full analysis of water samples and assess suitability for irrigation depending on the standard specifications of the Food and Agriculture Organization. As the analysis results showed that all the studied wells located within the water of light to moderate in terms of the seriousness of Electrical conductivity if used for irrigation, and sodium adsorption ratio values for all water wells studied were within the Has no influence soil permeability. It turned out that the Toxic Effect of these water plants were mild to moderate effect for sodium either chloride was degree selection of non-toxic to light moderate, and that the use method Piper for the classification of water showed that it quality predominantly Na+, Mg +2, Ca+2 - Mg+2 , Ca+2 for positive ions and water quality sulphurous HCO3-, SO4 = predominantly basal in terms of negative ions.