Strength Of Sand Research Articles

Soil stabilization using synthetic polymer for soil slope ecological protection

Polymer treatment can protect soil slopes by enhancing topsoil macro-properties and promoting vegetation growth. In the present study, laboratory and field application tests were performed on polyurethane (PU)-treated soil to investigate its effect on soil slope ecological protection, and the mechanism related to achieving the ecological protection of soil slopes was revealed. Laboratory tests show that PU addition could greatly enhance the unconfined compression strength of silty sand and its tensile and shear strengths, especially the first two, which increased from about zero to 952.61 and 211.47 kPa, respectively. The addition of PU also led to a reduction in permeability and an enhancement in water retention capacity. The permeability coefficient decreased by an order of magnitude, whereas the water retention capacity remained at a high and stable level for a long period with little water supplementation. In addition, the PU-treated soil showed satisfactory erosion resistance and protected vegetation growth to some extent, both depending on the amount of PU, whereas a competitive relationship was observed between the contribution of the PU amount to anti-erosion and the environment for plant growth caused by the PU content. Field observations showed that PU treatment could effectively and ecologically protect soil slopes by enhancing topsoil erosion resistance, mechanical strength, and water retention, thereby accelerating vegetation growth and cover. The PU stabilization effect benefits from the improvement in the microstructure of silty sand caused by PU adsorption, connection, and filling effects. This induced a denser and stiffer whole that covered on the slope surface, which, on the one hand, enhanced the stability of the slope surface and weakened the influences induced by rainfall and runoff and, on the other hand, promoted vegetation growth by reducing soil erosion and providing moisture.

Stress–Dilatancy Behavior of Biocementation-Enhanced Geogrid-Reinforced Sand

The performance of geogrid reinforcement is largely influenced by the interlocking effect between the geogrid and soil. To enhance the performance of geogrid reinforcement in sand, a novel biocementation-enhanced geogrid reinforcement method was proposed. Biocementation could be carried out in situ via microbially-induced carbonate precipitation (MICP). To understand the mechanisms of the biocementation enhancement effect, the stress–dilatancy behavior of coarse sand (CS) that was treated with the biocementation-enhanced geogrid reinforcement method was studied through a series of triaxial tests. The test results showed that the interlocking effect between the geogrid and CS could be effectively improved when the CS around the geogrid was biocemented by the calcium carbonate (CaCO3) that was generated in situ through MICP. The stress–dilatancy behavior of geogrid-reinforced CS was significantly enhanced after biocementation. In addition, the interlocking effect that was provided by the geogrid could mitigate or even avoid brittle failure, restrain the further development of dilation, and enhance the mobilization of the friction strength (qf) of the biocemented coarse sand (Bio-CS) during shearing.

The comparison of physical and mechanical properties of sand in Sedau and Obel-Obel Village

The research was conducted in two regencies: Sedau Village in West Lombok Regency and Obel- Obel Village in East Lombok Regency. The two research sites are areas with potential sand wealth, with many sand mining companies operating. The sand mining company at the research site is expected to implement good mining practices which pay attention to mining design safety. Geotechnical recommendations on slope dimensions with a good safety factor value are required in making a mining design. Several factors affect a rock’s geotechnical properties. These factors are physical and mechanical. In this study, a comparison was made between the physical and mechanical properties of sand at two locations, which aims to compare rock characteristics and become a reference for geotechnical recommendations in the area. The research method used was sampling and testing in the laboratory. The results showed that the porosity value in Sedau Village was 0.102 and Obel-obel Village’s was 0.09. The average water content value in Sedau Village was 6.567%, and the average water content value in Obel-Obel Village was 8.233%. The specific gravity value of sand in Sedau Village was 3.75 gr/cm3, and that in Obel-obel Village was 3.75 gr/cm3. The compressive strength of sand in Sedau Village was 0.137 Mpa, and the compressive strength of sand in Obel-obel Village was 2.32 MPa. Based on the laboratory testing results, the influencing factors were analyzed, namely the location of its formation and the different processes of sand sedimentation in Sedau Village and Obel-obel Village.

Investigation of shear strength of sand–bentonite mixtures with boron additives at high temperature for energy geo-structures

The soils surrounding energy geo-structures are exposed to high temperatures and temperature cycles. Changes in the engineering properties of soils should be investigated under thermal effects and soils that are highly durable against temperature changes are needed for thermo-active geo-structures. Generally, bentonite or sand–bentonite mixtures (SBMs) are preferred as natural barrier soil materials. Hence, the engineering properties of these natural soil materials against high temperatures should be improved. Boron, which has high thermal resistivity, reduces the heat expansion of materials, when added to soils may increase the durability of buffer materials at high temperatures. In the present study, the effects of tincal and ulexite additives were observed on the shear strength behavior of SBMs at 80 °C and room temperature. The general results showed that with the contribution of boron, the shear strength of the SBMs increased with increasing temperature. The effect was more pronounced for 20% SBMs at high temperature. Tincal and ulexite can be used to increase the shear strength of SBMs at high temperatures.

The effect of physical properties of sandstone on the compression strength of rock

Sandstone are commonly found on Lombok Island. The research aims to determine the sandstone’s physical and mechanical properties against the uniaxial compressive strength test. Analysis of physical properties for this research was carried out to determine the dimensions of size, moisture content, specific gravity, and bulk density, while the analysis of mechanical properties was to obtain compressive strength values. The original dry and wet bulk weights were obtained by testing the physical properties and compressive strength of sand and trass. The results from the samples in the Gunung Jae show that the average water content was 8.275%, the specific gravity was 2.37 grams, the bulk density was 0.485 gr/cc, and the compressive strength test was the highest value of 14 mm with the stress of 0.18 MPa.

ANALISIS PERBANDINGAN KUAT TEKAN MORTAR BERDASARKAN MODULUS HALUS BUTIR (MHB) PASIR SUNGAI DENGAN PASIR GUNUNG

Mortar is a cementation material composed of sand and cement with added water. River and mountain sand are types of sand that are available in large quantities in Bengkulu City. This study aimed to determine the effect of grain fine modulus from river sand on the compressive strength of mortar compared to Curup Mountain Sand. The sand river used was Kembang Sri River Sand (MHB 2,91), Penanding (MHB 2,204), Lubuk Kebur (MHB 3,452), Talang Rasau (MHB 2,257) and Curup Mountain Sand (MHB 1,29). The ratio variation between cement and sand used was 1Pc : 4Ps, 1Pc : 5Ps and 1Pc : 6Ps. Each variation was made 6 cube samples with a side dimension of 50 mm. The test was done at the age of the sample 28 days. The initial flow of the mixture plan is 105-115%. The results obtained of the highest value of mortar compressive strength for the mixture of 1Pc : 4Ps and 1Pc : 6Ps was found in Curup Mountain Sand, which was 14,08 MPa and 7,77 MPa. The highest value of mortar compressive strength for 1Pc : 5Ps mixture was found in Talang Rasau River Sand, which was 11.43 MPa (120,44% compared to Mountain Sand). The 1Pc:4Ps and 1Pc:6Ps mixture of Talang Rasau River Sand has a strength of 87.64% and 93.17% compared to Mountain Sand. Kembang Sri River sand has the lowest mortar compressive strength value for each mixture of 1Pc : 4Ps, 1Pc : 5Ps and 1Pc : 6Ps, compared to the strength of mountain sand was 34,80%, 27,40% and 28,57%. On the average, river sand with the gradation in zone III can be used for mortar mixture, although its strength is still below that of mountain sand.
 Keyword : river sand, mountain sand, mortar, fine modulus compressive strength.

Laboratory investigation and BP neural network modeling on heat-activated oil shale semi-coke attributable to the mechanical properties of concrete

Concrete construction requires the consumption of large quantities of raw materials. If oil shale semi-coke can be used in concrete projects in a reasonable way, not only will it ease the shortage of raw materials for concrete, but it will also consume oil shale semi-coke and reduce its ecological impact. This investigation aims to study the feasibility of using semi-coke in concrete construction based on its mechanical properties. The chemical components and microstructures of four thermal activation temperature oil shale semi-cokes were first analyzed by X-Ray Fluorescence (XRF) and scanning electron microscope (SEM). Then, by replacing the cement with equal mass of semi-coke, the effect of heat-activated calcination temperature and the amount of semi-coke admixture on the mechanical strength of mortars sand and concrete was tested. Finally, a BP neural network was used to establish a strength prediction model for semi-coke concrete and the evolution of internal pores of semi-coke concrete was analyzed by nuclear magnetic resonance (NMR). The results show that semi-coke is mainly composed of SiO2 and Al2O3, which can be used as a concrete mineral admixture for volcanic ash reaction. The oil shale semi-coke is flaky with a porous surface, resulting in the semi-coke contributing more to the flexural strength of the mortar than to the compressive strength. At the calcination temperature of 500 ℃ and a semi-coke content of 15%, the concrete has the lowest porosity and the best mechanical properties, and is therefore recommended. The developed BP neural network prediction model has a high prediction level and can provide guidance for practical engineering. The increase in the amount of coke admixture leads to a continuous increase in the number of pores in the medium and large pore sizes inside the concrete, which is the main reason for the change in concrete strength due to semi-coke.

Influence of fine content on undrained monotonic behavior of carbonate sand

The behavior of carbonate sand is different from that of siliceous sand in terms of high compressibility and crushability, specific particle shape, and physical properties. Thus, investigating the behavior of these soils is of great importance because of their prevalence in coastal areas. Nevertheless, a few studies have considered the presence of fines in the mixture with carbonate sand. The present study explores the influence of non-plastic fines on the undrained monotonic behavior of Bushehr carbonate sand. For this purpose, 30 undrained monotonic triaxial tests were performed on carbonate sand with silt ranges of 0% to 40% with two different void ratios. According to the results, the undrained shear strength of carbonate sand diminished with the addition of silt percentage up to 20%, and increased dramatically at 30% silt content. Also, the results of 40% silty sand revealed that this sample is stronger than samples with 10% and 20% silt content. By surveying the location of the phase transformation point in samples, it was observed that silt particles reduce the dilative phase. Also, confining pressure intensified the contractive phase while relative density had the opposite effect. The results showed that the effect of particle breakage is negligible in this study.

Effect of Bamboo biochar on strength and water retention properties of low plastic clay and silty sand

Biochar is a carbon-rich stable product derived from the thermochemical decomposition of biomass. The properties of biochar vary with types of feedstock, heating rate, pyrolysis temperature, etc. Consequently, the mechanical and hydrological properties of biochar amended soil (BAS) also differ with types of biochar and soils. However, the effect of bamboo biochar (BB) amendment on soil strength and water retention properties is missing in the previous literature. Bamboo biomass was pyrolysed at 600 °C to produce biochar. BB and soils (low plastic clay (CL) and silty sand (SM)) were mixed to prepare BAS. The samples were prepared by mixing BB in five ratios, i.e., 0%, 1%, 2%, 3.5% and 5% of dry soil weight. The biochar application has increased optimum moisture content, alkalinity (pH) and Atterberg limits, whereas, reduced maximum dry density and specific gravity of both the soils (CL and SM). The unconfined compressive strength (UCS) of CL soil was noted to increase by 10.5% with 2% biochar content and decreased after that, whereas the UCS of SM soil was found to decrease continuously with the biochar content increment. Therefore, the unconfined compressive strength (UCS) result showed that biochar application has contrary effects on both soils. The measured gravimetric water content (GWC) of BAS was increased with biochar increment in both soils. However, GWC increased more in CL than in SM soil at the same biochar content. The microstructural analysis showed that the biochar amendment filled the pore space of the soil matrix, resulting in an increase in UCS and GWC values. The increased water retention capacity and strength (UCS) of biochar amended CL soil provides evidence that it could be used as a landfill cover material.

Validity of Juang's Method to Predict the Liquefaction Potential of the Soils of Sablette Algiers

This work presents a deterministic and probabilistic analysis of the liquefaction potential of soils. Soil liquefaction is a process leading to the total loss of shear strength of loose sands under seismic stresses by increasing pore pressure. It is accompanied by deformations. Certain factors related to the characteristics of the ground and the seismic excitation can significantly influence the appearance or not of the phenomenon. Empirical methods of liquefaction potential assessment are widely used. The probabilistic method has been widely used for estimating the probability of liquefaction. Initially, the uncertain parameters are modeled by normal random variables. A parametric study of the coefficients of variation of the random variables showed that the number of strokes (N1)60 of the SPT test is the parameter that has the greatest influence on the probability of liquefaction. This study focuses on the liquefaction potential by methods based on the results of the in-situ "Standard Penetration Test" Through the results obtained in this study of the site of Sablettes in Algiers, in general, there is a risk of liquefaction of the soil in the sandy layers, and we can say that the site studied has an average liquefaction potential. According to the classification of liquefaction potential proposed by Juang et al., (2012).

Application and improvement of a stress partition framework-based methane hydrate-bearing sediment constitutive model for wide range confining stress

A constitutive model of methane hydrate-bearing sediment (MHBS) was recently proposed based on a stress partition framework (SPF-MHBS). To capture the mechanical behavior of MHBS under a wide range of effective confining pressures, this study introduces the equivalent granular void ratio (e*) and the particle breakage index (Br) associated with critical state variables into the original SPF-MHBS model. A comprehensive set of triaxial tests on MHBS under 0.2–20 MPa effective confining stress were simulated. The simulation results indicate that based on appropriate parameter calibration, the response of specimens under low effective confining stress can be acceptably represented using the original SPF-MHBS model. However, at high confining stress, the simulated strength of pure sand was overestimated, while that of the hydrate-bearing specimen was and underestimated. Dilatancy was also significantly overestimated at high confining stress. After introducing the e* into the original model, the performance under relatively low pressure is improved and three model parameters are reduced from the original model. After introduction of Br, the model performance is further improved at high confining stress. The improvements allow the SPF-MHBS model to provide a unified description of MHBS behavior under a wide range of confining stress.

Discussion of “Effects of Grain Size and Moisture Content on the Strength of Geogrid-Reinforced Sand in Direct Shear Mode”

Discussion of “Effects of Grain Size and Moisture Content on the Strength of Geogrid-Reinforced Sand in Direct Shear Mode”

Polynomial neural network model to estimate the stress–strain behavior of zeolite-cement injected sand

The process of cement production is costly and one of the main factors in carbon dioxide emission. Hence, part of it should be replaced with eco-friendly pozzolanic materials like zeolite. As the determination of shear behavior of injected sands is time-consuming and laborious, in the present research the polynomial neural network (PNN) model was used to predict stress (q)-strain (ε) behavior of zeolite-cement injected sand. For this purpose, a number of consolidated undrained (CU) triaxial tests was performed on sand samples injected with zeolite-cement grout. Due to the difference in the shear behavior of the injected sand before and after the yield point (YP), the stress–strain curves were divided into two parts (up to the YP and beyond the YP), and the curves of each part were predicted with separate relationships. The results revealed that the PNN-based equations can accurately estimate the q-ε curves of sand samples injected with zeolite-cement grout, such that the mean absolute percent error (MAPE) for testing data sets to estimate pre- and post-YP q was 7.79 and 5.38%, respectively. Sensitivity analysis indicated that up to the YP, the confining pressure (CP) was the most important parameter affecting the injected sand strength. The importance of water to cementitious materials ratio (W/CM) and cement replacement with zeolite content (Z) on the pre-YP q predicted by the PNN model was close to each other and less than the CP. Beyond the YP, the effect of W/CM, CP and Z was almost the same.

Study Method of Pile near Cohesionless Slope under Reversed Lateral Load Considering Sand Strength State and Lateral Deflection of Pile

A p-y curve method of pile near cohesionless soil slope under reversed lateral load is proposed. This method takes into account the failure mode of soil around the pile under reversed lateral load and the interaction mode between pile and soil, and derives the ultimate soil resistance of the pile. Considering the change of the original stress state of soil due to the lateral deflection of the pile foundation, the influence of the relative density, the initial mean effective stress and the lateral deflection of pile foundation on the internal friction angle of the sand is evaluated to further accurately calculate the soil resistance value at each depth. The prediction results of this method are well verified by comparing with the FE results and centrifuge test results. Finally, the influence of the process of lateral deflection of pile on the strength state of soil around the pile and the bearing capacity of pile is studied.

Experimental Study on the Effect of Ultrafine Mineral Admixtures on the Mechanical Properties of Cement Mortar

Objective: The effect of ultrafine mineral admixtures on the mechanical properties of grouting mortar was studied. Methods: In this paper, the compressive strength and flexural strength of the mortar with different contents of ultrafine mineral admixture replacing cement were tested respectively, and the heat of hydration was tested. XRD and SEM were used to analyze the changes in the microstructure characteristics after the addition of ultrafine mineral admixture. Results: after the addition of 5% ultrafine mineral admixture, the fluidity of cement slurry decreased by 25. 3%, and the fluidity gradually decreased with the gradual increase of ultrafine mineral admixture. With the addition of superfine mineral addition, The compressive strength increased steadily and gradually decreased thereafter, while the content of superfine mineral added was 20%, the strength of rubber sand reached the maximum value at 28 days, which increased by 23. 76% compared with the test block without admixture. The flexural strength of 3d and 7d of rubber sand was weakened by the incorporation of ultrafine mineral admixture, and the flexural strength of 28d increased slowly with the incorporation of ultrafine admixture, and the flexural strength value reached the maximum when the dosage was 25%. The heat of hydration and microstructure analysis showed that the sand system produced more hydrated calcium silicate gel filling into the structure of the sand after the addition of ultrafine mineral admixture. Conclusion: a certain amount of ultrafine mineral admixture has remarkable influence on the compression strength of rubber sand, and the flexural strength of 3d and 7d is weakened, and increases the flexural strength of 28d.

Effect of Varying Curing Conditions on the Strength of Biopolymer Modified Sand.

Recently, the improvement of the engineering properties of soil has been centered on using sustainable and eco-friendly materials. This study investigates the efficacy of three biopolymers: Acacia, sodium alginate, and pectin, on the unconfined compressive strength (UCS) of dune sand. The UCS test measured the effects of the biopolymer type and concentration, curing intervals and temperature, and moisture loss. The changes in the morphology caused by the biopolymer addition were examined via scanning electron microscopy (SEM). Results indicate that the UCS of the biopolymer-modified sand increased with biopolymer concentration and curing intervals. Varying the curing temperature from 25-110 °C, slightly affected the strength of the acacia-modified sand specimen, increased that of the sodium alginate-modified sand specimen up to a temperature of 85 °C, and continued to decrease that of the pectin-modified sand specimen as the temperature was increased from 25 to 110 °C. The SEM images indicated that the biopolymer's presence within the sand pores significantly contributed to the strength. Bond decomposition occurs at temperatures greater than 110 °C for sodium alginate and pectin-modified sands, whereas bonds remain stable at higher temperatures for the acacia-modified sand. In conclusion, all three biopolymers show potential as robust and economic dune stabilisers.

Laboratory investigation on liquefaction of sands and cemented sand mixes

ABSTRACT Liquefaction is considered one of the most common phenomena resulting in serious damage during earthquakes. Appropriate estimation of liquefaction potential, damping characteristics and shear modulus of soil under dynamic loading is crucial for precise dynamic response analysis and soil modelling problems. The present paper emphasises the influence of relative density, confining pressure, and shear strain on the cyclic response of sand specimens. A parametric study comprising varying relative densities (35–65%), confining pressures (100–150 kPa), and shear strain (0.015–1.3%) under 1 Hz loading frequency was conducted in the laboratory. The sand samples were subjected to a series of consolidated undrained cyclic triaxial tests. It is observed that with an increase in confining pressure and relative density, the pore pressure ratio reduced; whereas an increase in pore pressure ratio was witnessed with an increase in shear strain. The influence of cement inclusion on the cyclic response of the specimens is evaluated for varying cement contents (1–4%). The addition of 4% cement considerably enhanced the strength of sand and arrested the liquefaction instigation.

Novel Estimation of Time-Dependent Unconfined Compressive Strength of Sand Treated with Cement and Zeolite

Novel Estimation of Time-Dependent Unconfined Compressive Strength of Sand Treated with Cement and Zeolite

Experimental study on the effects of triangular groove inclination angles on the mechanical behavior of sand–concrete interfaces

The mechanical properties of pile–soil interfaces directly affect the bearing capacity of pile foundations. In this study, the effects of triangular groove inclination angles on the mechanical properties of sand–concrete interfaces were investigated. Random rough concrete surfaces were obtained through slurry intrusion testing, and the roughness of concrete surfaces was evaluated based on the sand cone method. According to the roughness of random concrete surfaces, five regular concrete surfaces with different triangular groove inclination angles were constructed. A series of direct shear tests between (i) sand and random concrete surface, (ii) sand and regular concrete surface, as well as (iii) sand and smooth concrete surface were performed. Moreover, a direct shear test of natural sand was conducted. Lastly, a shear strength model considering the triangular groove inclination angle of sand–concrete interfaces was established, and the shear failure mechanism of interfaces was discussed. The results firstly indicated that the shear stress-displacement curves of random rough concrete surfaces were ideal elastic-plastic curves; and the regular rough concrete surfaces were found to incur strain softening under a normal stress of 300 kPa. Secondly, the shear strength of sand–concrete interfaces increased with the increase in groove inclination angle of concrete interfaces. Thirdly, sand was found to achieve the highest shear strength, while sand–smooth concrete interfaces proved to attain the lowest. Lastly, the internal friction angle value of random concrete interfaces was shown to range between the values of concrete surfaces with triangular groove inclination angles of 70° and 90°.

Investigation of the effect of frequency on shear strength and damping of pure sand and sand stabilised with rice husk ash using cyclic triaxial tests

Rice husk ash (RHA), owing to its pozzolanic properties and wide abundance, is an additive that can be used as an alternative to cement to improve a variety of soils. Damping and shear modulus are two important soil dynamic parameters used to predict soil behaviour under dynamic loading. Therefore, in this study, materials were prepared and their specifications were determined. A cyclic triaxial device was used to determine the dynamic parameters (stress control). Subsequently, the results related to shear modulus and damping calculated for pure sand before and after stabilisation were analysed according to different percentages of stabilisers for two frequencies of 0.5 and 1 Hz. The results revealed the effect of different frequencies on the damping of pure sand, which differed for stabilised sand. In all stabilised specimens, the shear modulus decreased with increasing frequency. Additionally, the damping decreased with increasing frequency in the stabilised samples. The shear modulus increases with the increase in the amount of stabilisers. The results also showed the positive effect of partially replacing cement with RHA.