Soil-cement Mixtures Research Articles

Assessing river bank erosion on Majuli Island for strength and stability in resilient protection

ABSTRACT The present study addresses the issues and challenges of Brahmaputra river bank erosion near Majuli Island, Assam. For field study, the most vulnerable locations, namely (i) Ahatguri area, (ii) Okhala Chuk, (iii) Kamalabari ferry ghat, (iv) Cinnatoli Chapori and (v) Kandhulimari area are taken into consideration. Geometrical as well as geotechnical investigations were carried out to obtain detailed information for the stability analysis of river bank slopes of selected sites. Through 2-D finite element-based numerical tool PLAXIS2D, results indicated low stability of river bank due to low shear strength and ingress of moisture. To improve the strength and stiffness of the river bank soil, authors suggest a soil stabilisation technique using a Cement-Soil mixture with a 1:25 ratio (4%). The influence of improvement in the geotechnical properties was noted with the improvement in the stability of the river bank soil when assessed numerically. Results depicted that under ‘saturated and stabilized condition’, approximately 99% reduction in maximum total displacement and 55–85% reduction in maximum total strain was observed at all the five critical locations studied. Factor of safety values of stabilised bank was increased by 4.5 to 12 times, compared to the corresponding results obtained for ‘saturated and unstabilized’ condition.

Silty soil resilient modulus stabilised with cement and recycled aggregate

ABSTRACT The present study analysed the resilient behaviour of silty soils from the southern region of Brazil stabilised with cement and recycled aggregate (RA) from construction and demolition waste, with a maximum diameter of 4.8 mm. Its suitability for use in urban pavement layers has also been assessed. Cyclic triaxial tests were conducted on pure soil, soil-cement, and soil-cement-RA specimens under three compaction efforts: standard, intermediate, and modified. Based on the results of the cyclic triaxial tests, resilience modulus (MR) prediction models were calibrated. Subsequently, using the AEMC software, the useful life of an urban pavement was evaluated, considering the materials tested as base layers and subbase. The results indicate that incorporating cement and RA proved effective in stabilising the soil, significantly improving the resilient modulus compared to pure soil. When compacted at the modified energy and subjected to the highest stress levels, the soil-cement-RA mixture presented MR of 638 MPa, an increase of 50% compared with the soil-cement mixture, with MR of 426 MPa. The mechanistic analysis demonstrated that soil-cement and soil-cement-RA mixtures are suitable for use in base layers and subbase of urban pavements, with the soil-cement-RA mixture presenting better performance as a base material.

Incorporation of Liquid WTP Sludge into Compacted Soil–Cement Mixtures

The sludge from water treatment plants (WTP) is a waste from the water process. This study evaluated the effect of incorporating water treatment plant (WTP) sludge, replacing the water used in compacted soil–cement mixtures. The materials were characterized by Scanning Electron Microscopy (SEM) associated with Energy Dispersive Spectroscopy (EDS) and Atomic Absorption Spectrometry (AAS). The soil, with the addition of liquid WTP sludge, presented an apparent dry specific weight (ƴd) of 1.77 gf·cm−3, the optimum moisture value in the compaction test of 15%, and the cement contents tested were 7, 11, and 14%. The specimens were molded using a WTP sludge–cement–soil mixture under the conditions mentioned above, and the simple compression results showed values within the range of 2.5 to 9.3 MPa, as specified by the Brazilian Technical Standard (NBR) 8491/2012. The hydraulic conductivity performed on the test specimen after 28 days of curing resulted in a coefficient (k) of 7.49 × 10−9 cm·s−1, classified as little permeable. The result obtained from aluminum leaching was 0.12 mg·L−1, within the maximum limit allowed by NBR 10004/2004. Therefore, liquid WTP sludge has a significant capacity for incorporation into the compacted soil–cement mixture and the potential to manufacture ecological bricks, an alternative environmentally sustainable brick.

Experimental investigation of the bond strength between GFRP and steel bars and soil-cement

Steel rebars have been used in soil-cement mixtures to increase their flexural capacity in shoring projects. However, the interaction of the reinforcing rebars and soil-cement and their bond strength has been rarely considered. A practical formula for predicting the rebar-soil-cement bond strength considering the strength characteristics of both has not been developed. The current study performed 60 pullout tests of rebars embedded in soil-cement and analyzed the pullout mechanisms as well as the effective parameters on the pullout force. The test parameters were rebar type, size and embedded length. Smooth, ribbed steel and GFRP rebars in diameters of 8 and 12 mm were tested. A pullout frame was added to a universal testing machine and the load-displacement behavior of the rebars and induced cracking were analyzed. The results showed that the prevailing failure mechanism during pullout of the rebars from the soil-cement was slippage and not cone/splitting failure. During slippage, some the soil-cement adhered to the rebar between its ribs because of the low compressive strength of the soil-cement. With a 50 % increase in rebar diameter, the bond strength decreased about 18 % and 30 % for the ribbed and GFRP rebars, respectively. This indicates the importance of the rebar diameter on the bond strength. The steel rebars exhibited greater bond strength with soil-cement in comparison with the GFRP rebars. A new equation has been proposed to calculate the reinforcement-soil-cement bond strength by applying a reduction factor to the ACI equation.

ASSESSMENT OF THE POSSIBILITY OF USING RECYCLED COARSE AGGREGATE IN A WOOD-SOIL CONCRETE SLAB

Problem statement. During the process of post-war reconstruction in Ukraine, there will be a need for a large number of affordable and ecological building materials, especially in the part of restoration and construction of low-rise buildings. Such building materials can be soil-concrete and aggregates from crushed concrete waste. The proposed constructive solution of the ribbed floor, in which the ribs are made of pine beams and OSB sheets, and the slab part is made of soil concrete on fixed formwork. The purpose of the article is to determine the optimal composition of the soil-concrete mixture using crushed stone obtained after crushing concrete scrap, taking into account the configuration of the wood-soil concrete slab, to determine the strength of soil-concrete of this composition, to determine the possibility of using recycled coarse aggregates. Conclusions. Based on the results of determining the optimal composition of soil-concrete, it was established that the maximum compressive strength is achieved when the mass content of the binder in the cement-soil mixture is at the level of 20 %. Taking into account the configuration of the slab part of the floor, a fraction of 5...7.5 mm is accepted for coarse aggregate. During the test of soil-concrete samples with recycled aggregate with a mass content of 10 %, 20 % and 30 %, the compressive strength of soil concrete decreased. Obviously, the presence of a clay component (loam) in the mixture reduces the adhesion in the contact zone between the aggregate and the soil-concrete, which increases the heterogeneity of the entire structure of the soil-concrete. Thus, the use of natural or recycled coarse aggregates in soil-concrete is impractical. Taking into account the determined strength of soil-concrete without aggregate, a scheme of combined concreting of the soil-concrete slab is proposed – heavy concrete above the rib and soil-concrete in the overhangs. In this case, there is a need for research on the possibility of using recycled coarse aggregate of the required size in heavy concrete.

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 Varying The Content And Length Of Fibers In The Behavior of A Cemented Soil Efecto del Contenido de Fibra y la Variación de Longitud en el Comportamiento de un Suelo Cementado

This study presents the results of the effects of variation in the content and length of polypropylene fibers, when inserted into a soil-cement mixture, aiming its use as a primary coating for dirt roads. In this study, the experimental models were used: 5% fast-curing cement, clay sand of the Barreiras geological formation and polypropylene fibers of 6 mm and 24 mm lengths, at levels from 0.25%, 0.50% and 0.75% relative to the total dry soil-cement mass. After completion of the unconfined compression tests and tensile strength by diametrical compression, it was found that increasing fiber content in the soil-cement matrix provides: increase in resistance of the materials, increase on the voids content and the strain, but, significantly reduces the initial tangent modulus making the more ductile material. In the terms of length, it observed clearly that the 24 mm fiber has a stronger influence on the mechanical behavior when inserted into the matrix of the developed composite material.

Influence of industrial effluent treatment ettringite on the compressive and tensile strength and microstructure of soil-cement mixtures

It is increasingly important to find solutions for the problem of the aluminium anodising industry which generates a large amount of acid and alkaline wastewater, composed of high amounts of phosphates, sulphates, nitrates and aluminium. The sulphate removal trough ettringite precipitation is a simple process and involves a low-cost operating. The ettringite can be also formed during the cement hydration in soil-cement mixtures which causes several damages such as expansion. However, the effect of ettringite on the compressive strength, tensile strength and microstructure have few studies. This paper presents a novel experimental study on the influence of the industrial effluent treatment ettringite in resistance and microstructure of soil-cement mixtures. Experimental tests were performed using natural soil, soil mixed with 5% and 6% of cement and soil mixed with 5% and 6% of cement and ettringite for each material. The resistance of the materials was evaluated by unconfined compressive strength and indirect tensile strength, after 3, 7 and 14 days of cure. Additionally, several characterization tests and microstructure analysis were performed. Regarding the experimental results, the compressive strength and tensile strength decreases about 75% and 85%, respectively, when ettringite was added in soil-cement mixtures. The microstructure of natural soil, soil-cement and soil-cement-ettringite mixtures shows that the addition of cement and ettringite, simultaneously, increases the ettringite crystal formation mainly because the cement functions as a source of sulfate ions contributing with the formation of more crystals. Experimental results indicate that the incorporation of ettringite in soil-cement mixtures is not suitable for geotechnical applications.

Effects of Cement Treatment on Water Retention Behavior and Collapse Potential of Gypseous Soils: Experimental Investigation and Prediction Models

Gypseous soil poses a significant challenge in geotechnical engineering due to its susceptibility to collapse under saturation. This type of soil covers approximately 33% of regions in Iraq, primarily in unsaturated conditions. This study focuses on two types of gypseous soils: one with moderate gypsum content from Karbala city (G1) and the other with high-gypsum content from Tikrit city (G2), to investigate the effects of cement treatment on their water retention behavior and potential for reducing collapse. Different percentages of cement were mixed with both soils to determine the optimum soil–cement mixture for reducing collapse potential (CP) through single oedometer tests. The water retention characteristics and water retention behavior of samples with varying gypsum content and different levels of cement treatment were examined and compared using a controlled-suction oedometer. The soil–water retention curve (SWRC) of these natural and treated gypseous soils was also investigated and compared in both wetting and drying paths. Additionally, multiple pedotransfer functions (PTFs) were assessed to identify or adapt prediction equation(s) for the SWRC of gypseous soil both with and without cement treatment with acceptable accuracy. The results show that adding cement can decrease the CP of gypseous soils; it also affects their SWRC significantly. By making some simple modifications, the PTFs demonstrate acceptable estimations for the water retention curve of both natural and cement-treated gypseous soils.

Enhancing Soil Stabilization in Soft Soils Through The Addition of Sand to Soil-Cement Piles: a Comprehensive Study

Applying a soil-cement mixture to treat soft soil is an effective solution and is being widely applied in many countries around the world. In Vietnam, this method has also been used in many projects, especially in areas with weak soil such as riverside and coastal areas. The soil-cement mixture is made up of natural soil and cement. When cement is mixed with soil, the cement particles will react with water and minerals in the soil, forming a hard bond. The polymerization of this material is equivalent to the curing time of cement. This article focuses on researching the mixing of soil and cement materials to reinforce weak soil in Ben Tre province. Instead of just using cement for reinforcement, the article suggests adding sand and ECO-CSB or ECO-CSSB additives to the soil-cement mixture. Experimental results show that when sand and additives are added, the hardness and load-bearing capacity of the soft ground increase significantly. This method is especially suitable for treating soft soil contaminated with salinity in Ben Tre province. When adding ECO-CSB additives for non-saline soils and ECO-CSSB for saline soils, the amount of cement needed is reduced by 30% while still ensuring uniaxial compressive strength compared to when using only cement.

Replacement of Weathered Clay Shale Using Soil Cement for Bridge Approach Embankment in Purwakarta - Indonesia

Clay shale is a sensitive soil material that easily experiences weathering if exposed to open air, sunlight, water. Weathered clay shale is commonly located near the surface and has a soft consistency due to surface water infiltration. Referring to this condition, weathered clay shale is prone to experience soil movement if backfill work is conducted on the top side of weathered clay shale material. Therefore, to minimize the potential of soil movement during backfilling, soil replacement using soil cement is recommended to be conducted to gain higher soil shear strength and to prevent excessive water infiltration to the fresh clay shale. To gain further understanding, a comprehensive study about the replacement of weathered clay shale using soil cement for bridge approach embankment in Purwakarta was carried out. This study comprises site observation, field data collection, laboratory test, explanation about implementation and quality control. The stages in implementation of soil cement is carried out in several stages such as : evaluation of soil condition on the project site, checking the suitability of local soil for the soil cement stabilization, conducting field test trial mockup followed by quality control, conducting crumb test and mechanical properties test for soil cement mixture. Based on assessment results, the soil cement mixture shall be directly compacted after the soil cement mixture is homogeneous to prevent segregation and shall be given a curing time of at least 3-7 days without additional water to gain better soil shear strength. Furthermore, according to the crumb test result, soil cement material was identified as quite impermeable which is verified by evidence that there was no significant change in water content and the soil cement sample could still stand firm after soaked for 7 days.

Characteristics of the açai seed (Euterpe precatoria Martius) after thermal processing and its potential in soil-cement brick

The management of the açai palm, a species of the Euterpe genus, has grown in recent years mainly for the extraction of palm heart and the pulp of the fruit called açai. After the extraction of the’ pulp, there is a significant generation of residues, as the discarded seeds account for approximately 85% of the fruit. Therefore, this research aims to characterize the açai seed after fruit processing, as well as to evaluate the potential of thermally processed seed for use in soil-cement bricks. The seed morpho-anatomy tests were performed, including moisture content, loss of ignition, ash content, thermogravimetry, fluorescence, and X-ray diffraction of the ground seeds. Tests on thermally processed seeds included readings by X-ray diffraction and laser granulometry. After evaluating the properties of the ash, it was incorporated into soil-cement mixtures in proportions of 5%, 10%, 15%, and 20%, replacing the clinker content of LC3 (Limestone Calcined Clay Cement). Based on the results obtained, soil-cement bricks were produced with a composition of 90% soil and 10% LC3, with the LC3 cement clinker being replaced by 20% açai seed ash. The results indicate the potential for the application of açai seed ash in soil-cement bricks on a practical scale, demonstrating that the ash enhances soil stabilization and increases the compressive strength of the soil-cement matrix due to its smaller particle size compared to that of the soil grains. This not only reduces the amount of cement required for the matrix but also offers environmental sustainability through the utilization of seed waste. The study underscores the potential of applying açai seed ash in the context of environmentally significant alternative technologies and sustainable practices, emphasizing the promise of the properties found in discarded açai seeds.

Mechanical strength and Life Cycle Assessment (LCA) of soil-cement: comparison between mixtures of soil with ASTM type III cement, LC3, and the incorporation of by products and agroindustrial residues

Soil stabilization with binders is based on the binder action on soil particles, in turn causing an improvement in the mechanical behavior of the soil. Thus, this study aims to analyze the mechanical and environmental properties of soil-cement mixtures using Portland ASTM type III cement as binders and comparing to LC3 (Limestone Calcined Clay Cement), as well as incorporating extra raw materials such as silica fume, fly ash, sugarcane bagasse ash (Saccharum officinarum L) and açai seed ash (Euterpe precatoria Martius). The mixtures of soil, binder, extra raw materials were performed manually, and the cylindrical specimens (100 mm internal ø) were molded based on the AASHTO Normal Test. The results showed that the highest values of compressive strength ranged between 10 and 11 MPa, which were recorded for reference, soil-LC³ and soil-LC-açai seed ash mixtures. Life Cycle Assessment (LCA) was performed using the CML 2001 method with the aid of the OpenLCA software. Additionally, it was observed that the main emissions and consequences for the environment were from mixtures containing higher clinker contents.

Unconfined compressive strength assessment of soil-cement mixtures in Hai Duong city

The unconfined compressive strength (qu) of the soil-cement mixture (S-CM) depends on many factors, in which the soil type and the cement content (%CM) are very important factors. The soil type determines the fine particle content and affects the effectiveness of soil-cement mixture. Meanwhile, %CM has a direct influence on the qu of the S-CM. The cost of foundation treatment methods for small and medium-sized constructions depends on the reasonable cement content. This paper presents the unconfined compressive strength of S-CM for five common cohesive soils in Hai Duong city (soft clay, soft clayey sand, soft sandy clay, clayey sand mud, and sandy clay mud) with four cement contents (7%, 10%, 15%, and 20%). The research results show that the clayey sand (mbQ21-2hh) has the highest improvement efficiency compared to other soils, i.e., soft sandy clay (abQ23tb), soft clay (mQ21-2hh), sandy clay mud (mbQ21-2hh), and clayey sand mud (amQ21-2hh). The clay content has a great influence on the qu of S-CM. With the required value of qu28 = (8.0÷10.0) kG/cm2 (at 28 curing days), the reasonable cement content (% CM) is varied from 8% to 13% for soft sandy clay (abQ23tb), soft clay (mQ21-2hh), sandy clay mud (mbQ21-2hh), and clayey sand mud (amQ21-2hh); with the same value of qu28, the reasonable %CM is from 7.5 to 9.0% for clayey sand (mbQ21-2hh). The results are the scientific basis for recommending a reasonable %CM for each type of soil when designing to reinforce the foundation with soil-cement columns in Hai Duong city.

Influence of calcium carbonate sludge on cement-stabilized subgrade quality as investigated by means of electrical resistivity measurements

Calcium carbonate [CaCO3] is a key raw material used in the clarification of sugarcane juice for syrup production. The CaCO3 sludge produced during the clarification process is waste that needs to be stored, creating a geoenvironmental problem. On the other hand, it has been found that cement-stabilized subgrade is a suitable alternative for improving the quality of a subgrade course. This study aimed to investigate the influence of calcium carbonate sludge on the quality of the subgrade. The subgrade was composed of a mixture of 10% to 30% CaCO3 sludge, 1% to 3% of original Portland cement (OPC), and 67% to 100% of unqualified crushed rocks by weight. The modified Proctor method was used to compact soil–cement admixture samples, which were then tested for mechanical properties and electrical resistivity. The Wenner electrode array was used to measure electrical resistivity and compare it to the unconfined compressive strength of 16 different types of soil–cement mixtures after 7 days. The results of experiments show that the basic properties of CaCO3 sludge, when mixed with OPC and packed down, can make the best soil–cement mixture. As a result of this study, electrical resistivity was found to be in good correlation with unconfined compressive strength, thus opening up a time-saving and cost-effective way to check the quality of a soil–cement mixture.

Materials Characteristics of Soil-cement Samples under Various Maintenance Conditions

Subsidence of embankment foundation at the approach roadway is quite common in South Vietnam because natural soil layers are high water content and low bearing capacity. Soil-cement columns could be a potential method to deal with foundation subsidence. A critical issue is to determine proper soil-cement mixtures, mainly depending on maintenance conditions. In this study, materials characteristics of soil-cement samples are experimentally tested under various maintenance conditions. To achieve the objective, first, we drill to get natural soil samples at various depths for different boreholes located in southern Vietnam. Second, soil samples are used to fabricate soil-cement cylinder samples. Third, a set of fabricated samples are maintained under various environmental conditions for 7, 14, and 28 days. Last, experimental tests are conducted to test axial compressive strength to evaluate the effects of environmental parameters on strength development. The result reveals that the proportion of soil cement should be properly designed for soil layers to maximize the performance of the soil-cement column.

Soil-Cement Matrices for Additive Construction: 3D Printing System Validation and Printing Tests

Soil as a building material is gaining renewed interest from academia, and the construction sector, mainly for fabricating low-environmental impact homes. The fabrication of houses with soil using traditional methods such as adobe, cob, and rammed earth dates back to ancient times. However, emerging construction technologies, such as 3D printing, can be compatible with this material for building purposes. The article presents the validation of a 3D printing system for construction applications and the evaluation of soil-cement matrices' printability. First, the paper defines the printing parameters through experimental testing on soil matrices. Then, the article evaluates the printability of soil-cement matrices through filament printing and stacking tests. The results show that the 3D printing system prototype can fabricate small and medium-sized elements with soil matrices after correctly defining the pumping speed, printing speed, and layer height. Furthermore, experimental printing test results demonstrate that soil-cement matrices can be easily extruded and stacked; however, their printability capacity is strongly affected by the total water content and printing speed. This research highlights the suitability of soil-cement mixtures for additive manufacturing, a promising outcome that can facilitate the construction of homes in remote areas using 3D printing systems.

Dosage method for unconfined strength and fatigue life of fiber-reinforced cement-treated sand

Fiber-reinforcement has been reported as an effective and cost-attractive technique to improve the mechanical behavior of cemented soils. However, the dosage methodologies for these mixtures are still limited, especially regarding dynamic loading. The objective of this research was to analyze the dynamic response and strength behavior of fiber-reinforced cement-treated sand. In this sense, fatigue life, unconfined compressive strength, and split tensile strength tests were conducted. Results indicated that the mechanical behavior of the soil-cement mixtures was governed by fiber content, cement content and void ratio. The presence of fibers, the increase in cement content and the decrease in void ratio improved the overall mechanical behavior of all specimens. The porosity/cement content index resulted in a viable dosage method to predict both the monotonic and cyclic behavior of the mixtures. Lastly, the statistical analysis of variance corroborated the experimentally observed findings.

Nano soil improvement technique using cement

Nano soil-improvement is an innovative idea in geotechnical engineering. Nanomaterials are among the newest additives that improve soil properties. Herein, laboratory tests, such as unconfined compressive strength, direct shear test, and initial tests, were conducted to investigate the geotechnical properties of Kelachay clay with micro- and nanosized cement to evaluate its particles in untreated soil and observe changes in the behavioral properties of treated soil compared to those of untreated soil. Scanning electron microscopy and X-ray fluorescence images were analyzed before and after the grinding process to determine the nature of the studied particles. Furthermore, effects of time and nanocement content (0%, 1%, 3%, 5%, and 7%) on curing performance were evaluated. The optimum percentage of nano-cement was found to be 7%, which increased the unconfined compressive strength by up to 29 times and reduced the strain at rupture by 74% compared to the untreated soil. The results showed that nano-cement significantly improved the strength and stiffness of the soil–cement mixture by forming calcium silicate hydrate (C–S–H) gel that filled the pores and bonded the soil particles. Nano-cement also acted as a nucleation site for more C–S–H growth, enhancing the durability and strength of the mixture.

Relationship between Porosity and Water Permeability for Deep Soil Mixing Material

The deep soil mixing (DSM) method is used to improve the mechanical and/or hydraulic properties of soils. The DSM method refers to an in situ mixing of soil, water, and hydraulic binder without excavation. After describing the specific microstructure of DSM materials compared with soils or concrete, four porosity–permeability analytical models from literature and based on microstructural parameters (i.e., porosity and pore-size distribution derived from mercury intrusion porosimetry) were applied to predict the water permeability (K) of soil–cement mixtures. After comparing the estimated permeabilities (Kest) with the experimental measurements of such a parameter (Kexp) using a triaxial cell, an indicator parameter A (=Kest/Kexp) was proposed to evaluate the ability of each model to fit the water circulation in DSM material. By calculating the average ratio 〈A〉 from the 24 materials in the studied database, three of the four applied models satisfactorily estimated the water permeability of the studied DSM materials. To reach an 〈A〉 value closer to 1, an extension of the Aït-Mokhtar's model, initially developed for cementitious mortars, was proposed by considering the specificities of the DSM materials. If previous models used only the contribution of nanopores less than 100 nm to the water flow, the extended model considered the contribution of all pore populations in the permeability calculation. Such an approach resulted in a significant improvement in the matching between the calculated and measured permeabilities.