Laboratory Evaluation of Mixing Energy Consumption and Its Influence on Soil-Cement Strength (original) (raw)
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IJERT-Research of Characteristics of Deep Cement Mixing Columns in Treatment of Soft Soil
International Journal of Engineering Research and Technology (IJERT), 2021
https://www.ijert.org/research-of-characteristics-of-deep-cement-mixing-columns-in-treatment-of-soft-soil https://www.ijert.org/research/research-of-characteristics-of-deep-cement-mixing-columns-in-treatment-of-soft-soil-IJERTV10IS010252.pdf The article presents the content assessment of the application of deep cement mixing technology. From laboratory and field experiments with geological conditions in Duyen Hai-Tra Vinh areas, Vietnam, we will find out the factors that affect the quality and durability of the deep cement mixing column. At the same time, we can determine the optimal ratio about content of cement and water for soil samples after being reinforced to meet the economic-technical requirements. Finally, test data is analysed to serve calculations and simulation based on linear regression models of Microsoft Excel. Keywords-Deep cement mixing columns, soft soil, optimal ratio of water and cement, linear regression models.
Environment effect on mechanical parameters of soil-mixing
Technology audit and production reserves, 2024
Soil improvement is originally an economical solution to make soil buildable, particularly compared to deep foundation methods using piles. The object of this research is the understanding of the behavior of soil-mixing material, in particular, what concerns the effect of environmental parameters, whether: temperature, water table level, chemical attacks, the phenomenon of aging etc. on the mechanical and physical characteristics (resistance to simple compression, resistance to simple bending, modulus of elasticity, porosity, density, etc.), of a soil-mixing column, in the short term and long term. The big problem is how to carry out experiments in the laboratory, which will be representative of the different phenomena that take place on a real scale (on site). To do this, our approach consists of studying different soil-mixing mixtures composed of «artificial» soils (clay and sand) and a CEM III/C cement, and with a variable W/C ratio. After making the test pieces, with the different dosages of cements and a ratio between clay and fixed sand, they were kept under normal temperature conditions, in order to reach a maturation age (180 days), to be able to begin the series of experiments. Once the specimens were subjected to the aging test, let's begin to crush them with simple compression and simple bending. The parametric study highlights a percentage of clay beyond of which the resistance decreases and the rigidity of the material can pose a problem for certain structural uses. The different results obtained show that for a low cement dosage, the humidification-drying cycle influences both the resistance to simple compression and to bending simple, as well as the number of cycles affects the resistance values in a significant way. On the other hand, for a greater or lesser dosage of cement, the resistance values are not affected. Based on the results obtained, it is possible to conclude that the choice of cement dosage depending on the nature of the soil influences the soil-mixing column and plays an important role on the lifespan of the column; therefore, it is necessary to give primary importance to the choice of cement dosage depending on the nature of the soil treated.
Influence of Soil-Cement Composition on its Selected Properties
MATEC Web of Conferences
The paper discusses the results of mechanical and technological tests of soil-cement composites made with cohesive soil. The compositions of analysed soil-cement mixtures differed in terms of their cement paste volume fractions and water-cement ratios. Limiting values of these technological parameters that enable the application of the soil-cement mixtures obtained in real life conditions for the purposes of the Deep Soil Mixing (DSM) method were determined. Based on the test results obtained, it was found that mechanical properties of the materials analysed were very sensitive to changes in their compositions. Variations in the volume fraction of cement paste within the range analysed caused mechanical properties to change even by an order of magnitude.
Applied Clay Science, 2015
Where difficult foundation soils are encountered in civil engineering projects, deep soil mixing method is a choice as a solution to deal with the problem. In this soil improvement method, cement or lime in slurry form (wet method) or in dry powder (dry method) is mixed with the in situ soil. To the knowledge of the authors no comparison between cement and lime treated soil using wet or dry method has been made for saturated soils. In this research saturated bentonite-sand mixtures were treated with 2, 4, 6, 8 and 10% by dry mass of cement, lime and cement-lime using both wet and dry methods. Treated soil samples after curing periods of 7, 14 and 28-days were tested in unconfined compression strength and consolidation. The results of unconfined compression tests indicated that the strength of wet cement treated samples was higher than dry cement treated samples and this was opposite for lime treated samples. The results of consolidation tests in terms of the e-logσ v ′ relationship indicated that they were in general, function of the type and the amount of the admixture and the curing time. Compression index decreased with amount of additive in contrast with previous finding for cement treated samples of a low plastic clay soil. Lime treated samples showed higher elastic modulus than cement treated samples and dry treated samples in general showed higher elastic modulus than wet treated samples.
Experimental Investigation of the Effective Parameters on the Strength of Soil -Cement
Soil-cement is a mixture of Portland cement, soil and water, which are bonded together due to the cement hydration and compaction. It have durability, low permeability and resistance against wear. Water to cement ratio, cement content and type have been commonly investigated as the most effective factors on the compressive strength of soil-cement. This study aims at the investigation of the effects of some other factors, such as Sand Equivalent (SE), Plasticity Index (PI), and gradation of the soil on the compressive and flexural strength of soil-cement. Results show that the compressive and flexural strength of soil-cement increases with increasing the sand equivalent and decreasing the plasticity index of the soil.
This paper proposes a new soil treatment method that employs reinforced deep mixing method (RDMM). In this method, the deep mixing pile is reinforced in a manner similar to a spirally reinforced concrete column. This paper aimed to evaluate the effectiveness of RDMM on improving the strength and deformation properties of a non-plastic soil. Four (4) experimental phases are conducted in this study and these are: 1) Physical property tests of the base soil, (2) Unconfined compressive strength (UCS) tests on unreinforced cementadmixed soil specimens, (3) Unconfined compressive strength tests on reinforced cement-admixed soil specimens, and (4) Construction and load testing of full-scale reinforced deep mixing pile. The results unconfined compressive strength tests revealed that the influence of longitudinal bars on the unconfined compressive strength of reinforced cementadmixed non-plastic soil is pronounced at low cement contents
Ground improvement using soil–cement columns: Experimental investigation
Alexandria Engineering Journal, 2013
The construction of heavy structures on soils of low relative density is a challenging task. The inclusion of soil-cement columns produced by the deep mixing method is one of the soil stabilizing techniques that could be applied successfully to overcome this challenge. Nevertheless, this technique did not receive a considerable attention in Egypt yet. In the first part of this study, two different natural silty sand soils extracted from the Delta of the River Nile were mixed with cement to prepare samples of different cement doses and different water cement ratios. After curing, the hardened samples were tested and their unconfined compressive strength was investigated. The second part of this study investigates the interaction between a strip footing model and Nile deltaic soil improved by a group of soil-cement columns. Results of the first part of this study showed that the compressive strength of the investigated Nile delta soils could be increased even at lower values of cement doses. Results extracted from the second part of this study showed that a considerable settlement reduction up to 80% could be achieved depending on both the number and the length of the soil-cement columns that is used to improve the soil.
EFFECT OF CEMENT AND BY-PRODUCT MATERIAL INCLUSION ON PLASTICITY OF DEEP MIXING IMPROVED SOILS
Cement deep soil mixing is one of the most widely used ground improvement techniques to enhance the strength of weak soils for construction purpose. One of the engineering parameter that influences the strength performance of the improved soil is plasticity. This paper investigates the effect of cement and inclusion of waste materials on the plasticity of deep mixing improved soils. Two waste materials namely, Pulverised Fuel Ash (PFA) and Ground Granulated Blast Slag (GGBS) were considered. The investigation was carried out on five different soil samples with natural plasticity of 5%, 10%, 15%, 37% and 45%. In the first phase of improvement, samples were mixed with 5%, 10%, 15% and 20% cement (CEM I) content by weight of dry soil. In the second phase, the cement contents were reduced by 50% and replaced with PFA. In the third phase, cement was further reduced by 33.3% and replaced with equal amounts of PFA and GGBS. All improved samples were cured under 100% relative humidity and subjected to liquid and plastic limit test after 3days. Analysis of results showed that for cement improved soils, increase in cement content beyond 15% by weight of dry soil increases plasticity index of improved soils. The inclusion ofPFA and GGBS to cement during deep soil mixing reduces the plasticity index of the improved soil and may enhance the strength gain over time. PFA and GGBS could be used in deep soil mixing with reduced amount of cement and thus reducing cost, CO 2 emission and the environmental impact of cement deep soil mixing. The results have shown that 15% cement is the optimum amount of cement required for deep mixing improvement of soils with natural plasticity index of 5-45%. The inclusion of GGBS and PFA in the blended soil reduces the amount of cement required for optimum binder content and resulted to 20% Cement/GGBS/PFA optimum binder content in the ratio of 1:1:1. This study has shown that addition of 15% cement content and 20% Cement/GGBS/PFA resulted to improved soils with plasticity index less than 17% making the investigated soils suitable for use as embankments and pavement for light to medium traffic. It could also be added that soil-binder interaction depends on soil type and the extent of improvement in plasticity index depends on plasticity index of the natural soil. A generalised flow chart based approach as a function of plasticity index of the natural soil have been developed for selection of binder for use in construction where increase in strength is envisaged.
Geotechnical Testing Journal
This paper presents the possible inclusion of pulverized fuel ash (PFA) and ground granulated blast slag (GGBS) in cement deep soil mixing for enhancement of unconfined compressive strength (UCS) of weak soil materials for construction purposes. The main focus of this paper was to investigate the UCS of cement-, cement/PFA-and cement/PFA/GGBS-improved soils, and development of mathematical and graphical models for prediction of UCS for use in design and construction. Samples of cement, blends of cement and PFA, and cement/PFA/GGBS were prepared using 5 %, 10 %, 15 %, and 20 % by weight of dry soil and tested for UCS after 7, 14, 28, and 56 days. A multiple regression analysis was conducted using the SPSS computer program. The results showed that soil materials with lower plasticity show higher strength development compared to those of higher plasticity for cement improvement. The study has also revealed that the inclusion of PFA and GGBS can cause a reduction in the amount of cement in deep soil mixing, which can result to reduced cost and emission of carbon dioxide (CO 2) during construction. The developed mathematical and graphical models could give reliable predictions of UCS for weak soil materials with initial UCS less than or equal to 25 kPa and for water to binder ratio of unity based on the observed agreement between experimental and predicted data. The developed multiple regression models have also been validated using different mixtures of 6 %, 8 %, 12 %, and 16 % of binders.