Soil Cement Research Articles

Prediction of Ultimate Bearing Capacity of Soil–Cement Mixed Pile Composite Foundation Using SA-IRMO-BPNN Model

The prediction of the ultimate bearing capacity (UBC) of composite foundations represents a critical application of test monitoring data within the field of intelligent geotechnical engineering. This paper introduces an effective combinational prediction algorithm, namely SA-IRMO-BP. By integrating the Improved Radial Movement Optimization (IRMO) algorithm with the simulated annealing (SA) algorithm, we develop a meta-heuristic optimization algorithm (SA-IRMO) to optimize the built-in weights and thresholds of backpropagation neural networks (BPNN). Leveraging this integrated prediction algorithm, we forecast the UBC of soil–cement mixed (SCM) pile composite foundations, yielding the following performance metrics: RMSE = 3.4626, MAE = 2.2712, R = 0.9978, VAF = 99.4339. These metrics substantiate the superior predictive performance of the proposed model. Furthermore, we utilize two distinct datasets to validate the generalizability of the prediction model presented herein, which carries significant implications for the safety and stability of civil engineering projects.

The Creation of Geotechnical Seismic Isolation from Materials with Damping Properties for the Protection of Architectural Monuments

This paper presents the results of a study on the relevance of seismic isolation systems for protecting architectural monuments from seismic and vibration impacts. This work aims to develop a method for protecting architectural monuments from seismic and vibration effects by installing geotechnical seismic isolation systems made of various geomaterials, such as a silicate soil mixture (SSM), a cement–soil mixture (CSM), a bitumen–soil mixture (BSM), and a rubber–soil mixture (RSM). The novelty of the work lies in the results of studying the wave processes in different models of geomaterials to assess their effectiveness in a seismic isolation system in the form of damping barrier screens to ensure the seismic resistance of architectural monuments. By comparing the amplitude–frequency characteristics of various geomaterials, it was found that the rubber–soil mixture (RSM), the cement–soil mixture (CSM), and the bitumen–soil mixture (BSM) have the most effective damping properties. A proposed method for protecting architectural monuments with geotechnical seismic isolation in the form of vertical screen barriers and technology for their installation ensures the integrity and safety of architectural monuments at all stages of construction and operation.

Effect of Modifiers on the Disintegration Characteristics of Red Clay

Due to the high degree of weathering, the red clay slope has low anti-disintegration performance, and the clay easily becomes wet and disintegrates after soaking in water. It causes geological problems such as slope collapse caused by soil softening. To study the disintegration characteristics of modified red clay, the disintegration test of red clay modified by using lignin fiber, clay particles and lime was carried out, analyzing the disintegration characteristics of improved red clay from physical and chemical perspectives and analyzing the improvement mechanism of three modifiers with the scanning electron microscopy test. The analysis results show that the water-holding capacity and disintegration resistance of soil mixed with lignin fiber decrease; the disintegration time of reshaped red clay increases with the increase in clay content; and the average disintegration rate of the soil decreases with the increase in clay content. With the increase in lime content, the soil cement increases. The integrity of the soil is enhanced, and its anti-disintegration ability is improved; the saturated moisture content of reshaped red clay increases with the increase in lignin fiber and clay content, while the saturated moisture content of soil decreases with the increase in lime content. The damage analysis shows that the larger the damage factor of soil, the worse its anti-disintegration ability, and the easier the soil disintegrates. The purpose of this paper is to explore the essence of the soil disintegration phenomenon, and on this basis, using high-quality improved materials, to improve the soil, which easily disintegrates. This move aims to significantly enhance the anti-disintegration ability of the soil, thereby improving its resistance to softening and disintegration, thereby effectively improving and maintaining the ecological environment. At the same time, the improved soil will help to improve the utilization rate of the slope and foundation soil, thereby reducing the economic cost of maintenance engineering. Against the current background of sustainable economic, social, and ecological development, it is of great strategic significance to ensure the sustainable availability of land resources in specific areas and maintain their productivity and ecological stability for a long time. The research into this subject not only helps to deepen the understanding of soil disintegration, but also provides strong technical support for the rational utilization of land resources and the protection of the ecological environment.

Macro-micro mechanical behavior of saturated cemented sands during drained triaxial shearing

To enhance the understanding of the macro-micro mechanical behavior of cemented sands, a series of drained triaxial shearing tests were conducted on saturated cemented sands with varying cement contents and confining stresses. These tests incorporated high-performance acoustic emission (AE) monitoring and an environmental scanning electron microscope (ESEM) technique. The results yielded quantitative interpretations of macro-mechanical response, microstructural variation, and AE behaviors. Specifically, increasing cement content led to an exponential reduction in porosity (or pore area ratio) and a power increase in pore number, possibly due to the production of hydration products that segment large pores. Relationships were established among peak strength (or AE hits), cement content, and confining stress. However, AE trends diverged from those observed in peak strength due to microstructural modifications under different cement contents and their resulting differences in micromechanical behavior during shearing. General relationships between AE rate and mechanical parameters were established during the initial shearing stage, regardless of cement content and confining stress. Moreover, AE evolution efficiently characterized subtle variations in failure patterns due to its high sensitivity to failure-induced structural modifications. These contributions have the potential to establish a non-destructive field evaluation framework and provide guidelines for the efficient utilization of cemented soils in geological and geotechnical engineering applications.

Assessing the desiccation crack propagation performance of cemented soil reinforced by modified polyvinyl alcohol fiber

The increasing application of fiber reinforcement to mitigate desiccation cracks induced by evaporation during backfill curing addresses the dispersion challenge associated with high fiber addition. This study aims to enhance the interfacial strength between fibers and cement-soil mixtures through chemical modification methods (NaOH, HCl, and Silane Coupling Agent). By conducting a single fiber pull-out test and microstructures observation, the outcomes reveal that modified PVA fibers exhibit a notable increase in shear strength and pull-out energy compared to unmodified ones, thereby necessitating a reduced fiber dosage for desiccation crack reduction. Furthermore, this investigation delves into the Digital Image Correlation (DIC) feasibility of employing the Digital Image Correlation (DIC) method to monitor the desiccation crack pattern of cement-soil slurry during the initial hydration stages. The findings indicate that NaOH and HCl treatment notably diminishes stress concentration under drying conditions, consequently reducing crack width and area.

Progressive yielding/softening of soil–cement columns under embankment loading: a case study

Progressive yielding/softening of soil–cement columns under embankment loading: a case study

Experimental study on dynamic and static mechanical properties of polyvinyl alcohol fiber cement soil under salt freezing cycle

A universal testing machine and a 50 mm split Hopkinson pressure bar (SHPB) were used to conduct salt erosion and freeze-thaw (F-T) cycle coupling tests on cement soil specimens with 0.5% polyvinyl alcohol (PVA) fiber and without fiber in order to study the effects of salt solution and F-T cycles on the dynamic and static mechanical properties of cement soil. In four distinct solution settings (clear water, 9 g/L sodium sulphate solution, 9 g/L sodium chloride solution, and 9 g/L sodium sulphate and sodium chloride mixed solution). After F-T cycles, the cement soil specimens underwent the unconfined compressive strength (UCS) test, SHPB test, and SEM test. The findings indicate that as the number of F-T cycles increases, the dynamic and static mechanical properties of cement soil specimens decrease, and the rate of decline is rapid followed by slow. After five F-T cycles, the combined solution's unconfined compressive strength dropped to 15.91% (without fiber) and 29.41% (with fiber), respectively. After five F-T cycles, the dynamic compressive strength in sodium sulphate solution fell by 95.17% (without fiber) and 93.86% (with fiber). Fibers help to some degree by preventing salt erosion and F-T cycles. With more F-T cycles, the absorbed energy declines exponentially, and the order of the solutions' effects on the absorbed energy is: mixed sodium chloride and sodium sulphate solution > sodium chloride solution > sodium sulphate solution > clear water.

Enhancing riverbank stability: A case study on soil improvement through Jet grouting along Can Tho riverbank

Soil cement mixing (SCM) using a high-pressure grouting method (Jet grouting), considered an improvement solution for soft soil has been popular in countries, especially in Japan and other countries in Northern Europe. However, the implementation of Jet grouting is still quite modest in the Mekong Delta. In this study, the depth effect on the compressive strength of soil-cement mixing is conducted at the Can Tho River embankment project. The results show that the uniformity of SCM depends on the cement content. The higher cement content gives a better distribution of compressive strength from the bottom to the top of SCM. In this study, the cement content of 400 kg/m3, considered the suitable content for the Jet-grouting method in Can Tho, is much higher than in (TCVN 9906:2014).

Prediction of characteristics of soil-concrete massifs created by injection of extremely finedispersed binders (microcements)

The urgency of the problem associated with the use of injection erection technology of soil cementation in various engineering and geological conditions is substantiated. Due to the peculiarities of cementation technologies under various modes of injection impregnation and the possibility of applying certain technical injection parameters for different types of soils, it is possible to improve various deformation characteristics of the soil mass when implementing the technology. Some results of the analysis of the work of injection cementation of soils in dispersed soils are presented and general patterns are established under which it is necessary to adjust the parameters of cementation. The theoretical prerequisites are considered in relation to experimental data, the effectiveness of the application of cementing technology in the injection impregnation mode is proved and the general applicability of the application of these cementing methods with an increase in the technical indicators of the fixed soils is established.

Stabilization of micaceous residual soil with industrial and agricultural byproducts: Perspectives from hydrophobicity, water stability, and durability enhancement

Micaceous residual soil is prevalent in the tropical regions of southern China. However, it is generally deemed unsuitable as a construction material in earthen structures due to its inferior engineering properties. Despite previous research into stabilizing micaceous soils, there remains an urgent demand for sustainable alternatives to traditional stabilizers to achieve circularity. Furthermore, uncertainties regarding the long-term performance of stabilized soils under hydraulic conditions complicated their use in flood-susceptible areas. To provide a sustainable and low-cost solution for creating stabilized soil for earthen structures in waterlogged regions, this study explores the impact of coir fiber and fly ash, agricultural and industrial byproducts, on the hydrophobicity, durability, and water stability of micaceous residual soil from Hainan, China. The study commenced with the preliminary mechanical tests to ascertain the optimal dosage of coir fiber and fly ash, which were determined to be 1% and 15%, respectively. Then, hydrophobicity, durability, and disintegration tests are conducted on fiber-reinforced fly-ash-treated soil under various stabilization conditions. The microstructural evolution of the soil fabric in response to the stabilization process was meticulously traced using scanning electron microscopy and energy-dispersive spectroscopy. Results indicated that the addition of fly ash could impart severe and persistent water repellency to the studied soil, with the contact angle improving from 16.7° to 102.9°, and the water drop penetration time significantly extending from 3.6 s to approximately 600 s. While incorporating coir fibers into the cemented soil presented negligible improvement on soil hydrophobicity, it markedly enhanced the soil’s durability, mitigated moisture-related deterioration and decelerated disintegration. Notably, the strength residual ratio of fiber-reinforced cemented sample maintained higher than 90% even after 20-day water immersion, and the disintegration rate decreased by 57% compared to unreinforced sample. Microstructural analysis revealed that bonding, friction, and interlocking among fibers, hydration products, and soil particles are the main contributors to the stable and robust matrix, ensuring improved mechanical behavior and longevity of micaceous residual soil. This study provides an innovative method for utilizing waste byproducts in stabilizing micaceous residual soil, as a viable option for earthworks in rain-soaked or flood-prone areas.

Analysis of Mechanical Properties of Fiber-Reinforced Soil Cement Based on Kaolin.

Adding fibers into cement to form fiber-reinforced soil cement material can effectively enhance its physical and mechanical properties. In order to investigate the effect of fiber type and dosage on the strength of fiber-reinforced soil cement, polypropylene fibers (PPFs), polyvinyl alcohol fibers (PVAFs), and glass fibers (GFs) were blended according to the mass fraction of the mixture of cement and dry soil (0.5%, 1%, 1.5%, and 2%). Unconfined compressive strength tests, split tensile strength tests, scanning electron microscopy (SEM) tests, and mercury intrusion porosimetry (MIP) pore structure analysis tests were conducted. The results indicated that the unconfined compressive strength of the three types of fiber-reinforced soil cement peaked at a fiber dosage of 0.5%, registering 26.72 MPa, 27.49 MPa, and 27.67 MPa, respectively. The split tensile strength of all three fiber-reinforced soil cement variants reached their maximum at a 1.5% fiber dosage, recording 2.29 MPa, 2.34 MPa, and 2.27 MPa, respectively. The predominant pore sizes in all three fiber-reinforced soil cement specimens ranged from 10 nm to 100 nm. Furthermore, analysis from the perspective of energy evolution revealed that a moderate fiber dosage can minimize energy loss. This paper demonstrates that the unconfined compressive strength test, split tensile strength test, scanning electron microscopy (SEM), and mercury intrusion porosimetry (MIP) pore structure analysis offer theoretical underpinnings for the utilization of fiber-reinforced soil cement in helical pile core stiffening and broader engineering applications.

Coal-derived char for durability improvement of cement stabilized soil under freeze–thaw, wet–dry, and sulfate attack

Cement soil stabilization is widely used in civil engineering to improve the performance of soils subjected to freeze–thaw (F–T), wet–dry (W–D), and sulfate attack (SA). Due to the negative impacts associated with manufacturing cement, the development of eco-friendly and sustainable additives is highly desirable. Coal-derived char is a cost-effective byproduct of the coal pyrolysis process. In this study, the influence of coal char on mineralogical, microstructural, physical, and mechanical properties of cement stabilized soils (with cement contents of 0%–20% and char contents of 0%–30%) subjected to F–T cycles, W–D cycles, and SA is investigated. Compared to cement stabilized soils, char-cement stabilized soils exhibit up to 60.8% fewer volume changes during F–T cycles and 31.6% fewer during W–D cycles. The compressive strength of char-cement stabilized soils with cement contents of 5%, 10%, and 20% are on average 7.9%, 17.6%, and 11.0%, respectively, higher than that of cement stabilized soil subjected to F–T cycles, W–D cycles, or SA. The inclusion of char promotes cement hydration and results in the formation of more amorphous hydration products that fill voids or cover soil minerals. The findings indicate the promising potential of coal char in enhancing soil performance under a range of challenging environmental conditions.

Investigation of creep characteristics and microscopic mechanism of cemented-soil subjected to freeze-thaw

With the development of underground construction, higher safety demands have been placed on construction methods. The improved freezing method, which combines artificial ground freezing and cemented soil stabilization techniques, is more suitable for studying the typical creep characteristics of muddy clay in Shanghai. However, research on the creep behavior of freeze-thaw cemented-soil is limited. In this study, the creep characteristics of freeze-thawed cemented soil were investigated through triaxial creep tests, and the micromechanism was explored using scanning electron microscopy (SEM). The results indicate that the creep deformation of freeze-thawed cemented soil is higher than that of non-freeze-thawed cemented soil. The freezing temperature decreased with an increase in deformation. By analyzing SEM images, the porosities of non-freeze-thawed cemented-soil and soil freeze-thawed at -5°C, -15°C, and -25°C, were extracted, which were 28.5%, 28.7%, 30.1%, and 39.1% respectively. During the freeze-thaw cycle, both the soil and cemented soil particles undergo movement and reordering. Freeze-thaw exacerbates creep degradation because frost heave weakens particle adhesion and affects structural stability. These results provide a scientific reference for the development of underground spaces in soft areas.

Monitoring the hardening process of cemented soil with polymer optical fibre

Cement-soil can effectively improve the mechanical characteristics of soft soil and reduce the deformation of foundations through the physical and chemical processes of cement hydration. After mixing cement with soft soil, the hydration reaction of cement consumes a certain amount of water, which leads to a decrease in the water content. The early strength of cement-soil refers to the undrained shear strength within a few hours of mixing. The initial setting time of cement-soil can reflect its early strength development. In this study, polymer optical fibre (POF) sensors are used to visually monitor the early strength of cement-soil with different cement contents; the monitoring results show that the POF sensor can effectively visualize the hydration process of cemented soil. The cement-soil hydration process is divided into three stages: the initial setting time of the cement-soil is 13-15 h, and the final is 33-41 h. Furthermore, the cement content significantly influences the initial and final setting times of cement-reinforced soil. As the cement content increases, the initial and final setting times of the cement–soil decrease. This study proposes a new method for monitoring the strength of cement-reinforced soils.

Utilization of drilling waste when drilling wells in the fields of the western oil and gas region of Ukraine

The article analyzes known technological solutions for storage and processing of well drilling waste. The advantage of the solution is the presence of a soil-cement coating. The authors propose to fill the waste repository with alternating layers of drilling mud and fly ash of the Darnytsia Thermal Power Plant. The authors advise to use sorbents for neutralization of petroleum products as needed. It is suggested to introduce the sorbent periodically into the mud storage barn. The thickness of the layers for disposal with the addition of ash was chosen in order to obtain optimal humidity. It is proposed to add ash removed from the Darnytsia Thermal Power Plant when arranging the walls and coating of the mud storage tank from soil cement. When adding 10% of ash by weight of cement, the compressive strength increases by 8.01% on average, and when adding 20% - by 12.57%. The results obtained show that the average compressive strength of soil cement samples increases with an increase in the percentage of fly ash content. The results were compared to samples without additives.

Enhancing Soil Resilience to Climatic Wetting‐Drying Cycles Through a Bio‐Mediated Approach

AbstractClimatic wetting‐drying cycles exacerbated by climate change can trigger several weakening mechanisms in surface soils, potentially leading to instability and failure of slopes and earthen structures. This study proposes a bio‐mediated approach based on microbially induced calcite precipitation (MICP) to increase soil resilience to wetting‐drying cycles. To explore its viability and the underlying mechanisms, we conducted a series of laboratory tests on clayey soil that underwent six wetting‐drying cycles. The tests were conducted with different treatment methods to investigate the effect of treatment sequence and cementation solution concentration. After MICP treatment, the initial evaporation rate, surface crack ratio during drying, and total soil weight loss during rainfall erosion were reduced by up to 32%, 85%, and 90%, respectively. Spraying the cementation solution first in the MICP treatment sequence proves more effective in improving soil water retention capacity. On the other hand, initiating the sequence with the bacterial solution demonstrates a more pronounced effect in reducing soil desiccation cracks and erosion. Microstructure analysis reveals that the content and distribution of CaCO3 precipitation are the major factors controlling the effectiveness of MICP for the cementation of clayey soil. Employing MICP can minimize the carbon footprint and contribute to developing environmentally friendly solutions for soil improvement in regions affected by climatic wetting‐drying cycles.

Study on the shear characteristics of the cemented soil-concrete interface after artificial freeze-thaw under vibration loading

Underground construction has reduced underground space. Consequently, engineering construction is being done near existing structures. The artificial ground freezing (AGF) method is effective in such projects, and cement is often used to reduce frost heave and thaw settlement. A cemented soil-concrete interface is formed around underground structures. The interface serves as the primary medium for interaction between the two materials. Therefore, the shear characteristics of the cemented soil–concrete interface after artificial freeze–thaw cycles under the influence of the surrounding vibration load in underground engineering must be understood. This study conducted large-scale interface shear tests of a cemented soil–concrete interface with vibration loading. The effects of curing time and artificial freeze–thaw cycles on interface shear characteristics were studied. Furthermore, unconfined compressive tests of the cemented soil under artificial freeze–thaw conditions were conducted. The shear strength of the interface increased with curing time. The shear strength of the interface and the unconfined compressive strength of the cemented soil increased rapidly in the early stage of curing and gradually slowed after seven days. Artificial freeze–thaw reduced the shear strength of the interface with vibration loading. The results enrich ongoing research on the shear characteristics of cemented soil-concrete interfaces.

A micro-theoretical model for predicting the unconfined compressive strength of cement-sand reinforced soft clay

Cement-sand reinforced soft clay (C-SRSC) is a complex multiphase geomaterial. Its strength is determined by the physical properties of the internal multiphase substances and the coupling mechanical response between various phases of substances. By considering the effect of the particle size and content of sand particles on the unconfined compressive strength (UCS) and failure mechanism of C-SRSC, the C-SRSC is divided into two phases of the cement soil matrix and sand particles to construct a micro cell model of C-SRSC. Based on the strain gradient theory, the theoretical model of the UCS of C-SRSC based on the physical mechanism at the microscale is derived. Forty five groups of UCS tests were conducted to analyze the effect of sand particle size and content on the UCS of C-SRSC, and to calculate the theoretical model parameters. The results show that the UCS of C-SRSC increases with increasing curing age, cement content, and sand particle content, and decreases with the increasing sand particle size. The theoretical model of the UCS of C-SRSC based on physical mechanism initially verified the consistency of the experimental and theoretical results.

Soil-cement columns for high-rise buildings: design–testing–construction–monitoring: A case study of green solution in Vietnam

Soil cement columns (SCCs) are commonly used to reinforce soft ground to support roads and railway embankments, or to withstand horizontal pressure for deep excavations. This study presents another application of SCCs as load-bearing foundations for high-rise building projects. SCCs with a diameter of 800 mm, length of 10 m, cement content of 350 kg/m3, and an unconfined compressive strength (UCS) of 3.6 MPa were applied. In this study, five single columns and one group constituting two columns were constructed, and core drilling and axial static load tests were conducted. The test results indicated that the SCC could achieve a load of 1,650 kN for a single pile and 3,300 kN for the group constituting two columns. In total, 1,123 columns were designed and constructed for this project. Compared with conventional reinforced concrete pile methods, a project using SCC could save 30 construction days and 20% of the total cost. Moreover, SCC can be considered a green and environmentally friendly foundation solution because it does not use concrete or steel materials and does not produce waste soil.

Analysis of Kinang Jingkion Material as Road Subbase Layer Using Soil Cement Method

This research aims to analyze the California Bearing Ratio (CBR) and Unconfined Compressive Strength Test (UCS) values as road foundation layers using local materials, namely Kinang Jingkion. The soil and Kinang Jingkion materials for the study were taken from the Apalapsili quarry in Yalimo Regency. Additionally, the additive or soil stabilizer used was matos obtained from the testing of soil characteristics, including sieve analysis or gradation, Standard Proctor Test for light density, and liquid limit test. After testing, it was found that the soil from the Apalapsili quarry is granular soil and can be categorized as A-1-a according to SNI 03-6797-2002. Subsequent testing involved CBR and UCS testing on Mix Designs made of soil and cement with concentrations of 4%, 6%, and 8%. Next, additional Mix Designs were created with compositions of Kinang Jingkion, soil, cement at 4%, 6%, and 8%. Further Mix Designs included compositions of Kinang Jingkion, soil, matos at 2%, and cement at 4%, 6%, and 8%. From the UCS testing results, Mix Designs with soil and cement concentrations of 4% and 6% did not meet the compressive strength criteria, with compressive strength values of 9.26 Kg/Cm² and 17.4 Kg/Cm² respectively. According to SNI 6887-2012, the compressive strength value after 7 days of immersion should be within 25-35 Kg/Cm², while other Mix Designs met the criteria of SNI 6887-2012. CBR testing also utilized the same Mix Designs, and the highest CBR result was obtained from the Mix Design with compositions of Kinang Jingkion, soil, cement at 8%, and matos at 2%, with a CBR value of 112%. According to the 2018 Revised General Specifications, a CBR value of 112% indicates a Class A Foundation Layer.