Compressive Strength Of Cemented Soil Research Articles

Effect of Organic Matter Components on the Mechanical Properties of Cemented Soil.

The organic matter in soft clay tends to affect the properties of cement-stabilized soil. The influence degree of different organic matter varies. In this paper, the influence weights and mechanism of the main organic matter components fulvic acid and humic acid on the mechanical properties of cemented soil were investigated. Impacts of FA/HA (fulvic acid/humic acid) values and curing time on the unconfined compressive strength, deformation characteristics, and microstructure of cemented soil were explored through the unconfined compressive strength test and electrical resistivity test. The results show that with the increase of FA/HA, the unconfined compressive strength of cemented soil gradually decreased and the plastic properties enhanced. The increase in curing time changed the stress-strain relationship of cemented soil, and some specimens showed brittle damage. The initial resistivity and structural property parameters of cemented soil gradually decreased with the increasing FA/HA value and increased with the increase of curing time. It revealed the influence law of FA/HA and curing time change on the microstructure of cemented soil. Based on the experimental results, the quantitative relationship equations between FA/HA and curing time and unconfined compressive strength, failure strain, deformation modulus, and resistivity were established.

Efficient machine learning method for evaluating compressive strength of cement stabilized soft soil

To meet the design strength of cement stabilized soft soil (cement soil) in different application environments, numerous field and indoor geotechnical tests are often conducted. These tests not only result in the unreasonable use of materials, cost and time, but also cause serious environmental pollution problems. This study aims to propose an efficient machine learning model to evaluate the compressive strength of cement soil. Firstly, a database containing 566 samples was developed by literature collection. Secondly, eight machine learning models were established to train and test the database, as well as evaluated for the generalization ability using six performance indicators. Finally, the optimal model was selected to conduct the correlation importance analysis of feature variables using shaply additve explanations and partial dependence plots, and compared with the typical empirical model. The results indicated that the compressive strength of cement soil was better predicted by extreme gradient boosting model (the determinate coefficient of model in the test set was 0.93). The cement content, water content, curing age and fine grain were the main feature variables influencing the compressive strength. A reliable database and machine learning model are proposed, which have practical reference for the design and construction of cement soil in soft foundation projects.

Corrosion Resistance and Compressive Strength of Cemented Soil Mixed with Nano-Silica in Simulated Seawater Environment

Cemented soil structures are frequently exposed to the corrosive environment of seawater for an extended period, severely affecting their interior structure and mechanical qualities. This study presents laboratory-based approach to investigate the effect of nano-SiO2 on the structural and mechanical properties of cemented soil in a simulated seawater environment. The unconfined compressive strength (UCS), elastic modulus and other mechanical properties of cemented soil mixed with nano-SiO2 and ordinary silicate cemented soil were evaluated. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to deduce the crystalline composition and microstructure characteristics of the modified cemented soil. The results show that the addition of nano-SiO2 greatly increased the compressive strength and corrosion resistance of the cemented soil. In a 3C (105% salinity) simulated saltwater curing environment, the compressive strength of the cemented soil containing 2% nano-SiO2 increased by 86% and 158% at 30days and 60days, respectively. XRD and SEM showed that nano-SiO2 enhanced the interface structure of cemented soil and increased the compactness of the cement-soil system. The current study demonstrates that nano-SiO2 could considerably improve the mechanical characteristics and corrosion resistance of cemented soil when exposed to simulated seawater.

Influence of Seawater Erosion on The Strength and Pore Structure of Cement Soil with Ferronickel Slag Powder

To promote the recycling of industrial waste residues in the reinforcement of foundation soil, the anti−seawater erosion of cement soil with ferronickel slag powder in the marine environment was studied. Specifically, this paper employed ferronickel slag powder to partially replace the cement. Then, the apparent morphology, unconfined compressive strength, and nuclear magnetic resonance (NMR) tests were performed on specimens of cement soil with ferronickel slag powder soaked in purified water and seawater. The research results reveal that with the rise in the content of ferronickel slag powder, the erosive effect of seawater on cement soil weakens, while the compressive strength of cement soil increases first and then decreases. With an excessive amount of ferronickel slag powder added to the cement soil, its chemically active effect decreases, leading to a decrease in the strength of the cement soil. When the admixture of ferronickel slag powder in cement soil is 45%, it achieves good performance. The addition of ferronickel slag powder improves the plasticity of cement soil. The higher the content of ferronickel slag powder, the greater the failure strain and residual strength of the cement soil. Microscopic studies indicate that with the increase in the content of ferronickel slag powder, the pores in the cement soil become smaller and smaller, the total pore volume decreases, the continuity of the pore size distribution improves, and the structure becomes more compact, thus enhancing the erosion resistance of cement soil.

Compressive strength of cemented soil in pre-bored grouted planted piles under negative temperature environment

As a new type of pile, if the pre-bored grouted planted nodular (PGPN) pile can be successfully applied to the permafrost engineering, it will have significant economic and ecological values. However, the law of strength development of cemented soil of PGPN pile under warm permafrost environment is still unclear. In this study, the strength characteristics of cemented soil were examined through unconfined compressive strength test, and factors such as the curing time at negative temperature, the types of cementitious materials, and the dosages of cement and early strength agent (ESA) were considered. The experimental results indicate thatthe cemented soil with sulpho aluminate cement (SAC) and Ordinary Portland cement (OPC) + ESA as cementitious materials show high strength and stable performance. In addition, the Reasonable dosages of the cement and ESA were suggested, respectively.

Correlating failure strength with wave velocities for cemented sands from the particle-level analysis

Measurement of elastic wave velocities allows engineers to effectively characterize and monitor the stiffness and strength development of the cemented soils. Several correlations between elastic wave velocity and strength, as well as correlations between small-strain modulus and strength, have been proposed for different materials. However, since the physical justification of the stiffness-strength correlation is not fully understood, criticisms and diverse views still exist. This study derived the analytical correlation between the elastic wave velocity (or small-strain stiffness) and the unconfined compressive strength of cemented soil, based on a simple cubic packing of coated equal-sized spheres. The analytical derivation suggested a one-parameter power function between the strength and the wave velocity or stiffness, with the power index of 4 and 2 for wave velocity and stiffness, respectively. To verify the derived correlation model, a first-hand laboratory database was used. Factors affecting the correlations are also discussed.

Mechanical Performance and Microscopic Mechanism of Coastal Cemented Soil Modified by Iron Tailings and Nano Silica

In order to explore the effect of composite materials on the mechanical properties of coastal cement soil, cement soil samples with different iron tailings and nano silica contents were prepared, and unconfined compression and scanning electron microscope tests were carried out. The results show that: (1) The compressive strength of cement soil containing a small amount of iron tailings is improved, and the optimum content of iron tailings is 20%. (2) Nano silica can significantly improve the mechanical properties of iron tailings and cement soil (TCS). When the content of nano silica is 0.5%, 1.5%, and 2.5%, the unconfined compressive strength of nano silica- and iron tailings-modified cement soil (STCS) is 24%, 137%, and 323% higher than TCS, respectively. (3) Nano silica can promote the hydration reaction of cement and promote the cement hydration products to adhere to clay particles to form a relatively stable structure. At the same time, nano silica can fill the pores in TCS and improve the compactness of STCS.

Test Research on Mechanical Property of Cemented Soil Strengthened with Basalt Fiber

To enhance the mechanical property of cemented soil, this paper discusses the way of improving the mechanical performance by incorporating basalt fiber into cemented soil. Unconfined compressive strength test is conducted on cemented soil with basalt fiber of different proportions, and the results show that the incorporation of basalt fiber can significantly improve the compressive strength of the cemented soil samples at different ages, but its strengthening effects weaken steadily with the increase of fiber amount. The incorporation of basalt fiber can enhance the plasticity of cemented soil, and the sample at its peak stress can still bear some loading, with some residual strength existing, propitious for the enhancement of engineering safety and stability. Additionally, the relations between the compressive strength and ages of cemented soil with basalt fiber of different proportions are established based on the experiment results, which can provide some references for practical projects.

Dynamic Mechanical Properties and Fractal Characteristics of Polypropylene Fiber-Reinforced Cement Soil under Impact Loading

This paper aims to study the dynamic mechanical properties, failure patterns, fractal behaviors, and energy dissipation of polypropylene fiber-reinforced cement soil under impact loading. Dynamic compression tests for reinforced cement soil with different polypropylene fiber contents of 0%, 0.4%, 0.8%, and 1.2% were conducted using a 50 mm diameter split Hopkinson pressure bar (SHPB) device. The static and dynamic stress-strain curves, dynamic strength increase factor (DIF), fractal behaviors, and energy dissipation properties of polypropylene fiber-reinforced cement soil were investigated and analyzed. The experimental results indicated that the dynamic strength increase factor (DIF) of cement soil increases firstly and then decreases with the increase of polypropylene fiber content from 0% to 1.2%. The maximum dynamic compressive strength of cement soil was obtained with adding 0.8% polypropylene fiber. With the increase of polypropylene fiber content, the average particle size of cement soil fragments has an increasing trend, whereas the fractal dimension presents a decreasing trend. Besides, the fragmentation degree of cement soil decreases correspondingly with the increase of polypropylene fiber content. The fractal dimension value has a linear relationship with the polypropylene fiber content and a decreasing exponential relationship with the average particle size. The absorbed energy per unit volume of cement soil presents an increasing trend firstly and a decreasing trend subsequently as the polypropylene fiber content increases from 0% to 1.2%. When the fractal dimension of cement soil is kept in the range of 2.04 to 2.15, the absorbed energy per unit volume of cement soil increases first and then decreases. The absorbed energy per unit volume of cement soil has a quadratic parabola relationship with polypropylene fiber content and fractal dimension, respectively. At last, the relationship of the absorbed energy per unit volume, fractal dimension, and polypropylene fiber content can be established, which can be used in the studies of dynamic behaviors and fractal properties of the fiber-reinforced cement soil under impact loading.

Effect of VOCs pollutants on strength of cemented soil

Based on the soil conservation project of a chemical plant in Zhenjiang, the effects of volatile organic compounds (VOCS) pollutants on the strength of cement soil were studied experimentally. Xylene was utilized for indoor experiment. The specimen was made of water, xylene solvent, gray yellow clay and 42.5 ordinary Portland cement in a certain proportion. Firstly, the influence of the content of xylene on the unconfined compressive strength of cemented soil with time was analyzed, and then the effect of cement blending ratio on the unconfined compressive strength of samples containing xylene was studied with the increase of time. The results showed that the unconfined compressive strength of cement-soil samples increase with the increase of time and decreased with the increase of xylene content in similar curing time; the same xylene incorporation and the unconfined compressive strength of cement soil samples increased with the increase of cement incorporation ratio. In addition, the author also verified the impact of VOCs pollutants on cement-soil retaining walls by simulating actual engineering, and proposed two solutions which were expected to advise the engineering.

Strength Test Research on Cement-Soil of Peat Soil in Kunming

Based on the engineering properties of the peat soil in Kunming, through indoor unconfined compressive strength test in this article, and changing the different cement mixing ratio including 12%, 15%, 18%, 21%, 24% and 27% and age including 3 d, 7 d, 14 d, 28 d, 60 d and 90 d, and we focus on the influence on unconfined compressive strength of cement-soil by both of them. Through the study of the regression analysis of test results, we obtain the basic strength characteristics of cement-soil of peat soil which is that cement-soil unconfined compressive strength increases with group of the cement mixing ratio and age and showing a good correlation between them. And the unconfined compressive strength of cement-soil with the increase of ratio presents approximate linear growth and a logarithmic curve approximation along with the age growth, and the growth rate is smaller and smaller.

Analysis of Engineering Characteristics of Cement Soil with Low Mix Additions

The mold bag cement soil was used to be as the material of dike core while building cofferdam. So the engineering characteristics of cement soil with low mix additions were analyzed in this paper. It was pointed out the unconfined compressive strength of cement soil is mainly related to the property of soil, water content, cement mixing content and degree of mixing uniformity, but has little to do with curing condition, cement adding way and the property of mixing water.

Laboratory Experimental Research on Mix Ratio Test of Cement Soil

Based on the generalization and analysis of laboratory experimental results on mix ratio, the effects of various factors such as cement content, water-cement ratio, curing time, curing conditions and types of cement on the mechanical properties of unconfined compressive strength of cement soil are presented. Results show that the unconfined compressive strength of cement soil increases with the growing curing time, and it is greatly affected by the cement content, water-cement ratio, cement types and curing time, while the effect of curing conditions is weak with a cement content of more than 10%. Moreover, the stress-strain of the cement soil responds with the cement content and curing time, increasing curing time and cement content makes the cement soil to be harder and brittle, and leads to a larger Young's modulus.

Experimental Study of the Impact of PAM on Cement Soil Strength

This paper studys the effect of PAM on the strength of cement-soil by different PAM content cement soil unconfined strength test combined with a scanning electron microscope test to have a microscopic analysis of the impact mechanism of PAM on the strength of cement-soil, hoping to cement soil engineering applications to provide a reference. The study shows that: when cement content is 10%, the compressive strength trend of cement soil is first rose and then decreased with the increase of PAM content . Cement-soil that was mixed with an appropriate amount of PAM can effectively improve the compressive strength of cement-soil and there is an optimal content.