Effect Of Sand Content Research Articles

Experimental Investigation of the Soil-Water Characteristic Curves (SWCC) of Expansive Soil: Effects of Sand Content, Initial Saturation, and Initial Dry Unit Weight

Soil-water characteristic curve (SWCC) is an essential parameter in unsaturated soil mechanics, and it plays a significant role in geotechnical engineering to enhance theoretical analysis and numerical calculations. This study investigated the effects of key factors, such as the percentage of sand, initial degree of saturation, and initial dry unit weight, on the SWCC of expansive soil by measuring the matric suction using a pressure apparatus method. The empirical equation of SWCC was obtained using the Van Genuchten and Fredlung Xing models, and the processing of experimental data checks the fitting of the two empirical models. The findings revealed that the Fredlung Xing model fit the relationship between matric suction and volumetric water content of expansive soil better than the Van Genuchten model, indicating that the pressure apparatus approach’s experimental data are correct and acceptable. The study also found that the matric suction increased with decreasing percentage of added sand at the same volumetric moisture content, and the increase in initial dry unit weight increased the matric suction, with the water retention capacity decreasing significantly after adding 20% sand. Moreover, as the initial degree of saturation increased, the volumetric water content decreased, and the characteristic curves became identical when the initial saturation degree reached 90%. Finally, to minimize the water retention capacity of expansive soils, the study recommended adding a percentage of sand not less than 30% to the expansive clay sample.

Research on the effect of sand content on stress and durability of cement

With the progress of science and technology and the improvement of people’s quality of life, the demand for materials is getting higher and higher. As one of the most important civil engineering materials, concrete is widely used to repair a large number of broken infrastructures. Its production uses sand and aggregate from quarrying operation. If the use is unreasonable, a large amount of waste will be produced. In addition, there is a significant shortage of natural building raw materials in many regions (especially in developed regions). So improving the sustainability and durability of concrete materials can save transportation costs. This paper mainly discusses the influence of sand content in cement concrete on the performance of the material itself. The maximum pressure resistance of the corresponding specimen is measured by the pressure sensor and other experimental instruments, and compared with the specimen of different shape and volume under the condition of different sand rate. By changing the ambient temperature, the number of times that the specimen does not conform to the specified standard value is measured, and the durability of the specimen with different sand ratio is obtained. In this work, the optimal sand gravel ratio is successfully and relatively accurately measured. And it can be reasonably used in infrastructure construction.

Elastoplastic Modeling of Sandy Clays Based on Equivalent Void Ratio Concept

Naturally sedimentary soils, such as marine clays, weathered residual soils, and glacial deposits, usually possess a certain amount of sand particles. These types of soils could be classified as sandy clay, because the coarse fraction is usually under the transitional content. Their mechanical properties (e.g., compressibility and shear strength) are dominated by the clay matrix and significantly affected by the evolving interparticle structure. Previous research into sandy clay is experimental or numerical, and theoretical investigations that considered the reinforcing effect of coarse inclusions have seldom been reported. Therefore, the effect of sand content was incorporated based on the equivalent void ratio (e*) and equivalent compression curve (ECC) of sandy clays. A unified structure parameter (χ) was introduced, which could capture the reinforcing effect of sand particles on the stiffness and shear strength of sandy clays well. The constitutive relationship was formulated by incorporating the equivalent void ratio concept into an elastoplastic framework. Validation of the proposed model was achieved by comparing the predicted results with experimental data that were compiled from the literature. This revealed a satisfactory prediction for the mechanical response of sandy clays and other gap-graded soils (i.e., gravel–clay mixtures) with a broad spectrum of coarse fractions.

Improving hydro-mechanical behavior of loess by a bio-strategy

Loess is widely distributed all over the world, covering about 10% of the land surface on earth. China is one of the countries with the most serious loess soil erosion in the world, especially the loess plateau. This is mainly related to the poor water stability and mechanical properties of the loess. A new coupling method of bio-cementation (Microbially Induced Calcite Precipitation: MICP) and sand additive to improve the hydro-mechanical behavior of loess was proposed. The feasibility, coupling improvement mechanism and the effects of sand content, bio-cement treatment cycle and cementation solution (CS) concentration were investigated through a series of tests. The results indicated that the proposed method was effective to improve the water stability and structure strength of loess. The coupling improvement performance were positively related to the sand content. When the sand content was 40%, compared to bio-cement treatment, the coupling treatment was 9 times deeper in treatment depth, 3.5 times stronger in peak structure strength, and the sum slaking rate was less than half. The coupling improvement mechanism can be attributed to the form of the double layers including hard crust and cemented layer. With the addition of sand, the thickness, structure strength and water stability of the double layers increased. The main reason is that there were more interfacial voids between sand particles and loess particles, increasing the permeability of loess and treatment depth, forming more amount of calcium carbonates. Based on the experimental condition in this study, 1.0 M of CS concentration was the optimal spaying strategy to improve the hydro-mechanical properties of loess.

Study of the influence of sand on rheological properties, bubble features and buildability of fresh foamed concrete for 3D printing

Using sand to partially replace binder in the preparation of foamed concrete (FC) can reduce shrinkage, result in a lower carbon footprint, and enhance eco-friendliness. The hardening properties and application of 3D printed FCs (3DPFC) are closely related to its performance. The effects of sand content and fineness on the rheological properties, buildability, pressure field, and bubble features of the FC used for 3D printing were studied and discussed. It was found that the doped sand competed with water in the surrounding paste, thus increasing the interparticle interaction force and difficulty of bubble integration, resulting in the decrease of air content and bubble diameter of FC. The static yield stress and thixotropy of sand-containing FC depends on the thickness and rheological properties of the bubble-containing paste layer around the sand particles. Replacing the binder with sand, especially with fine sand, intensifies the pressure field in the FC during the mixing process. The buildability of 3DPFC is linearly correlated with the average bubble diameter of FC. A formula is proposed to predict the buildability of 3DPFC based on the static yield stress and air content.

Effect of sand content on bond performance of engineered geopolymer composites (EGC) repair material

Engineered geopolymer composites (EGC) have recently emerged as a greener and more environmentally friendly alternative to conventional engineered cementitious composites (ECC), achieving excellent mechanical and durability properties. This study investigated the effect of sand to binder (S/B) ratio on the bond performance of EGC repair material with concrete and steel reinforcement. The S/B ratio of EGC mixes was varied from 0.3 to 1.0, and its effect on the physical and mechanical properties was evaluated. It was found that increasing the S/B ratio decreased the micro-cracks at the EGC-concrete interface and, increased the bond strength. A direct correlation was observed between the elastic modulus of EGC and its bond strength with concrete substrate. The EGC-steel rebar pull-out strength initially increased and then decreased with the S/B ratio. The EGC repair material with S/B ratio more than or equal to 0.8 achieved the minimum EGC-concrete bond strength value of 1.5 MPa, as recommended by the BSI code.

A modified series-parallel electrical resistivity model of saturated sand/clay mixture

Electrical resistivity tomography, ERT, is a geophysical method that is used to image subsurface geomaterials for various geological, environmental and geotechnical engineering problems. The success of ERT depends on the availability of a robust electrical resistivity model of soils that is able to characterise the different type of soils using its electrical resistivity measurements. The aim of this paper is to present an electrical resistivity/conductivity model for isotropic saturated sand/clay mixture that considers the effects of sand content, and surface conduction of clay content. The proposed model is formulated using a modified series-parallel mixing model theory which uses phase-volumetric and surface conduction model parameters. The phase-volumetric parmeters describe the configuration of the different soil/water phases in a representative soil unit cell which includes solid soil particles, free water, diffuse double layer (DDL) water. The surface conduction model parameters are used to describe the volume fraction of DDL water in the unit cell, and its electrical conductivity compared to the electrical conductivity of free water. Simple test methods are used in this study to determine the proposed model parameters. Laboratory experimental programme was also conducted in this study to validate the proposed model. Two types of clays, namely, kaolin and bentonite, and one type of clean sand were used to constitute five different sand/clay and clay/clay mixtures. Dynamic compaction method using Standard Proctor tools was used to constitute the testing samples. The electrical conductivities of different reconstituted soil samples were measured and compared with the proposed model predictions, and a good agreement was achieved. The small differences between the model predictions and the experimental measurements could be attributed to the slight deviation of the laboratory test samples from the model assumptions, which require the soil sample to fulfil fully saturated and electrical isotropy conditions.

Effect of sand content on engineering properties of fly ash-slag based strain hardening geopolymer composites

Strain hardening geopolymer composite (SHGC) is a tailored group of sustainable high-performance fibre reinforced geopolymer composites with strain hardening behaviour and ultra-high ductility. This paper experimentally investigates the effect of fine silica sand content (0–40% by weight of the geopolymer binder) on engineering properties of fly ash-slag based SHGC cured at ambient temperature, including workability, setting time, drying shrinkage, compressive strength, and flexural strength as well as deflection hardening behaviour that is particularly emphasised. The results indicate that all SHGC specimens exhibit deflection hardening characteristics along with large deflection and multiple microcracks distributed over the tensile side of the specimens. The widths of microcracks are within 300 μm and mostly smaller than 45 μm. The flowability, setting time, drying shrinkage and compressive strength of SHGC reduce with the increase of sand content at early ages up to 28 d. However, at 28 d, the incorporation of sand up to 20 wt% increases the flexural strength and toughness of SHGC, but the further increase of sand content up to 40 wt% results in a decrease in flexural strength and toughness.

Correction to: Effect of Sand Content on the Liquefaction Potential and Post-Earthquake Behaviour of Coode Island Silt

In the original publication of the article, the table header values in Table 1 were published incorrectly.

Effect of Sand Content on the Liquefaction Potential and Post-Earthquake Behaviour of Coode Island Silt

Traditionally, sandy soils are known to be the only type of soils susceptible to liquefaction. However, liquefaction has also been observed in silty and clayey soils. As one of the most problematic soft soils in the state of Victoria, Australia, Coode Island Silt (CIS) extends from the northern shoreline of Port Phillip Bay to the south and west of Melbourne central business district and contains a considerable and variable amount of sand. Although this material covers an area of more than 20 km2 at a depth varying from ground level to 30 m below the ground level in the metropolitan region of Melbourne, the effect of sand content on the liquefaction potential and post-earthquake behaviour of CIS has never been studied properly. Through an extensive set of monotonic, cyclic and post-cyclic triaxial tests, this paper explores the earthquake and post-earthquake response of CIS containing variable sand content. Based on the test results, it is found that the sand content up to 60% does not affect the liquefaction potential of CIS under the tested cyclic stress ratio. Also, it is found that although the applied cyclic loading does not considerably alter the internal friction of CIS-sand mixtures, the post-cyclic secant stiffness increases dramatically.

Effects of sand contents on mechanical characteristics of methane hydrate-bearing sediments in the permafrost

As a new resource, NGH (Natural gas hydrate) has aroused wide concern around the world, and it is instructive to use mechanics experimental technique to research the strength and deformation characteristics of hydrates and their sediments. In this research, firstly the triaxial compression tests had been conducted under various conditions, and the influence of sand contents on the mechanical characteristics of sediments containing methane hydrates was researched. The results showed that the stress-strain type was affected by quartz sand content, and the failure strength increased as sand content rose. The confining pressure, temperature and strain rate also had a remarkable influence on the failure strength of samples. Moreover, according to Mohr-Coulomb failure criterion, the mathematical relationships between the inner friction angle, the cohesion force and the sand content were also set up, and it was found that the inner friction angle was greatly changed by the sand content of the sediment matrices.

Effect of Sand Content on the Workability and Mechanical Properties of Concrete Using Bottom Ash and Dredged Soil-based Artificial Lightweight Aggregates

The objective of this study is to examine the workability and various mechanical properties of concrete using artificial lightweight aggregates produced from expanded bottom ash and dredged soil. Fifteen concrete mixes were classified into three groups with regard to the designed compressive strengths corresponding to 18 MPa, 24 MPa, and 35 MPa. In each group, lightweight fine aggregates were replaced by using natural sand from 0 to 100% at an interval of 25%. Thus, the density of concrete ranged between 1455 and 1860 kg/m3. Based on the regression analysis using test data, a reliable model was proposed to clarify lower early-age strength and higher long-term strength gains of lightweight aggregate concrete (LWAC) when compared with the predictions of the fib model. The proposed model also indicates that a lower water-to-cement ratio is required with the decrease in the natural sand content to achieve the designed compressive strength of concrete. The partial use natural sand is favorable for enhancing the tensile resistance capacity, shear friction strength, and bond behavior with a reinforcing bar of LWAC. The fib model overestimates direct tensile strength, bond strength and the amount of slip at the peak bond stress of LWAC. Therefore, it is necessary to consider the density of concrete as a critical factor in conjunction with its compressive strength to rationally evaluate the various mechanical properties of LWAC.

Yielding behaviour of cemented binary mixture

Cement stabilization is commonly used for improving soft soils and the mechanical behaviour of cemented pure clay has been well documented. However, limited studies have investigated the effect of sand in a cement-clay matrix because the conventional water to solid (solid includes soil and cement) ratio cannot be simply used to characterize the behaviour of cemented binary mixture. The water holding capacity of the mixture reduces with increase in sand content, when the water to solid ratio is kept constant. In this study, the ratio of water to clay and cement is kept constant, so that the effect of sand content could be studied. The materials used in this study are kaolin clay, sand with D50 of 0.71 mm and Ordinary Portland cement type 1. Sand content varies from 0% to 50% and curing time is kept constant at 7 days. We used three ratios of water to clay and cement which correspond to 139%, 104% and 78%. The isotropic yield point increases with increase in sand content and cement content, while it reduces with increase in water content. A power function captures the variation of yield point with the ratio of water to cement and clay.

Evaluation of Strength behaviour of Cement-RHA Stabilized and Polypropylene Fiber Reinforced Clay-Sand Mixtures

In this paper, regarding the high availability of rice husk ash (RHA) in Guilan province, also, to decrease the geo-environmental issues caused by dumping RHA in the environment, different clay-sand mixtures are stabilized using the combination of cement and RHA. Polypropylene (PP) fibers are also used to decrease the growth of tensile cracks and increase the overall strength of samples. As the main scope, effect of sand content (in different conditions: with and without presence of RHA) on the compressive strength of stabilized and reinforced samples is investigated. In this regard, 28 day cured clay-sand samples are prepared and unconfined compressive strength (UCS) tests are conducted and the results are compared. It is obtained that with addition of 20% sand to the clay samples, their UCS increases in both cases of non-RHA and RHA-stabilized samples. Moreover, such behavior has been observed with the length of studied PP fibers. As the second scope, based on the conducted UCS tests on the 7-, 28- and 90- day cured clay samples, compressive strength of non-RHA samples are almost completely achieved in a 28-day curing period, while samples containing RHA continue to strengthening after such a period toward a 90-day curing period. Next, a simple relationship for the prediction of UCS of cement-RHA stabilized and PP reinforced clay is presented based on the evolutionary polynomial regression (EPR) technique. This relationship can be efficiently applied by construction engineers to obtain the appropriate mixture design for the stabilization of clay with cement, RHA and PP fibers.

Long-term dynamic behaviour of Coode Island Silt (CIS) containing different sand content

The foundations of nearshore and offshore structures are always subjected to long-term cyclic loading which is often a one-way, with low amplitude and a large number of cycles. Hence, the long-term dynamic behaviour of shoreline soils and sediments should be understood to avoid excessive deformation and liquefaction. As one of the most problematic soft soils in Melbourne, Coode Island Silt (CIS) at the northern shoreline of Port Phillip Bay contains a considerable but variable amount of sand. This paper explores the dynamic response of CIS containing different sand content subjected to a large number of cycles. To determine the liquefaction potential, and the effect of sand content on the resilient modulus and permanent strain of CIS, a series of long-term cyclic triaxial tests at a sinusoidal loading frequency of 1 Hz is performed. Based on the test results, it is found that CIS with varying sand content up to 30%, does not liquefy under the cyclic stress ratios and frequency applied in this study. Also, a sand content of 10% causes CIS to degrade more under cyclic loading. In the end, an empirical model to predict the permanent strain of CIS with a variable sand content is calibrated.

Temperature Changes in the Vicinity of Thermally Loaded Structure Embedded in the Soil: Effect of Sand Content and Saturation Degree

Abstract Due to the rapid development of geothermal technologies, the problem of efficient and proper evaluation of soil thermal conductivity becomes extremely important. Factors mostly affecting the soil conductivity are the conductivity of solid phase and the degree of saturation. The former one is mainly affected by the mineral composition, in particular, by the content of quartz whose conductivity is the highest one among all the minerals forming soil skeleton. Organic matter, because of its relatively low conductivity, influences the solid conductivity as well. The problem addressed in the paper is the influence of mentioned factors on temperature changes in the vicinity of thermally loaded structure embedded in the soil medium. Numerical simulations are carried out for different values of soil thermal conductivity resulting from various quartz contents and degrees of saturation. In addition, a weak coupled - heat and water transport - problem is considered.

Effect of sand content on strength and pore structure of cement mortar

The effects of four sand contents on the compressive, flexural and splitting-tensile strength of cement mortars were evaluated. Moreover, we experimentally investigated the pore structure of cement mortar brought about by changing the sand content and water/cement ratio. The changes in the pore structure were quantified by measuring the porosity and pore size distribution obtained by using mercury intrusion porosimetry (MIP) technique. The test results show that the strengths of cement mortar increase with increasing sand content. It is also suggested that the traditional water/cement ratio law can be applied to cement mortar with different sand contents, provided that a slight modification is introduced. Sand content is an important parameter influencing the pore structure of cement mortar. Moreover, there is a good relationship between the pore structure and strength of cement mortar.

Effects of sand content on initial gravel motion in gravel‐bed rivers

AbstractWhen fine sediments are present in gravel streambeds (gravel‐framework beds), the gravel can be more easily removed from its original position, compared with gravel in a streambed without fine sediment but otherwise under the same hydraulic conditions. In this study, the effect of the presence of sand on the initiation of gravel motion in gravel riverbeds was investigated using flume experiments. The relationship between the critical Shields stress for gravel motion initiation and the fraction of sand in the bed was determined experimentally. The results can be summarized as follows. (1) When the fraction of sand in the bed is smaller than about 0.4, the critical Shields stress for the initiation of gravel motion decreases with increasing fraction of sand. The critical Shields stress increases, however, with increasing fraction of sand when it is larger than about 0.4. (2) The difference between the value of the critical Shields stress predicted by the Egiazaroff equation and the value obtained from the experimental data becomes maximum at about 0.4 of the fraction of sand. Here an empirical relation between the critical Shields stress and the fraction of sand is proposed so as to consider the effects of the ratio of the characteristic gravel size to the mean size of the bed material on the critical Shields stress. (3) Gravel in armored beds can be more easily mobilized by supplying sand as part of a sediment augmentation scheme. The sand fraction in the subsurface layer of the bed appears to reduce the friction angle of exposed particles. Sediment augmentation using sand has been recently demonstrated to be a viable alternative for mobilizing gravel for the restoration of gravel‐bed rivers downstream of dams. The quantitative evaluation obtained through the experiments reported here may be useful for the design of augmentation schemes. Copyright © 2017 John Wiley & Sons, Ltd.

Effect of sand content on stabilization of dredged soil - steel slag mixture

Effect of sand content on stabilization of dredged soil - steel slag mixture

Effect of Sand Content on the Filter Cake Properties and Removal During Drilling Maximum Reservoir Contact Wells in Sandstone Reservoir

The drilling mud program contains many tests such as filtration rate and filter cake properties to select the proper drilling fluid additives that yield the standard ranges of the viscosity, filtration rate, etc. However, the physical and chemical changes in the mud composition during the mud circulating will cause changes to the filter cake properties. The changes in the filter cake properties should be considered in the mud design program to prevent the problems associated with the change in the drilling fluid properties. For long horizontal wellbores penetrating plastic formations, the two sources of solids in filter cake are drilling chemical additives and formation cuttings (sand particles in the case of sandstone reservoir). This study focuses on the effect of introducing sand particles from the drilled—formations on the filter cake properties. Real drilling fluid samples from the field were collected at different location during drilling a 3600 ft of the horizontal section of a sandstone formation. Calcium Carbonate (CaCO3) was used as weighting material in this filed. The drilling fluid samples were collected at two different points: the flow line coming from the well after shale shaker and the flow line going to the well to verify the effect of separation stages on filter cake properties. The primary drilling fluid properties of the collected samples were measured such as density and rheological parameters. High pressure high temperature (HPHT) filter press was used to perform the filtration and filter cake experiments at 300 psi differential pressure and room temperature (25 °C). The mineralogy of the external filter cake formed by fluid loss cell is determined using SEM (scanning electron microscopy) and XRD (X-ray diffraction). Finally, solubility test was conducted to evaluate the effect of sand particles on filter cake removal (containing Calcium Carbonate as weighting material) using chelating agent: glutamic diacetic acid (GLDA) at pH 4. The results showed that for long horizontal sections, the effect of introducing sand particles to the composition of the filter cake can cause significant change to the properties of filter cake such as mineralogy, thickness, porosity, and permeability. For instant the thickness of filter cake increased about 40% of its original thickness when drilling sandstone formation in horizontal well due to fine sand particle settling. The filter cake porosity and permeability increment in the first 2000 ft part of the horizontal section was observed clearly due to the irregular shape of the drilling particles. However for the points after the first 2000 ft of horizontal lateral, the porosity and permeability almost remained constant. Increasing the sand content up to 20% degrade the dissolution rate of calcium carbonate in the GLDA (pH = 3.8) to 80% instead of 100%.