scholarly journals Investigation of Engineering Properties of Cement-Stabilized Calcareous Sand Foundation

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Yuan Chai ◽  
Dai-Ping Jiang ◽  
Fu-Jiang Wang ◽  
Hai-Bo Lyu
Keyword(s):  
Bearing Capacity ◽  
Cement Content ◽  
Soft Soil ◽  
Friction Angle ◽  
Engineering Properties ◽  
Calcareous Sand ◽  
Uniaxial Compression Strength ◽  
Engineering Characteristics ◽  
Apparent Cohesion ◽  
Engineering Problems

Calcareous sand is widespread around Nansha Islands, South China Sea. In oceanic and coastal engineering, calcareous sand is usually used as a building foundation and backfill material for airport runway embankments. The engineering characteristics of calcareous sand is different from terrigenous sand because of its irregular grain shape, lower particle strength, and internal voids, which have caused many engineering problems in the last decades. Cement-stabilized soil, as a common foundation reinforcement method, can solve these engineering problems and improve the foundation strength effectively. Therefore, it is very important to estimate the engineering characteristics of cement-stabilized calcareous sand foundations. In this paper, the basic engineering characteristics, bearing capacity, and deformational behavior of calcareous sand were studied by carrying out a series of tests on cement-stabilized calcareous sand. It is found that: (1) the uniaxial compression strength of calcareous sand is higher than that of Guangzhou soft soil but lower than that of filter medium quartz sand; (2) the deformation of the calcareous sand under compression is mainly plastic, and the elastic deformation gradually increases with increasing cement content; (3) the apparent cohesion of calcareous sand increases, while internal friction angle decreases with increasing cement content; (4) cement-stabilized method can significantly improve the bearing capacity of calcareous sand foundation, especially for the saturated state. A cement content equal to or more than 15% and a thickness of 1/8 of the foundation can effectively improve the bearing capacity of the foundation; and (5) the ultimate bearing capacity of the foundation by numerical calculation is higher than that by experiments, while the settlement by calculating is lower.

Analytical Study of Load-Settlement Behavior of Soil Treated with Stone Columns have Different Sectional Shape

2020 ◽  
Vol 857 ◽  
pp. 319-327
Author(s):  
Moataz A. Al-Obaydi ◽  
Zeena A. Al-Kazzaz
Keyword(s):  
Bearing Capacity ◽  
Soft Soil ◽  
Engineering Properties ◽  
Stone Columns ◽  
Equivalent Diameter ◽  
Element Analysis ◽  
Cross Sectional ◽  
Treated Soil ◽  
Almost All ◽  
Sectional Shape

Stone columns have been used widely to improve the engineering properties of the weak soil. Most of the previous works considered a circular section for the stone columns. In the present study, finite element analysis has been carried out to investigate the effect of stone columns shape and length on the settlement and bearing capacity of soft soil. Accordingly, three types of cross sectional shape for stone columns have been selected which they are circular, rectangular, and square sections with equivalent area. Various length of columns are adopted with diameter of 0.75m that achieved length to diameter or equivalent diameter ratios (L/d=2, 4, 6, 8, and 10) of columns spacing (S/d=3). The results show that the stone columns has tangible effects on the settlement of the soil while has minor effects on the bearing capacity. The settlement of the treated soil with stone columns have L/d=2, reduces by 18.0, 17.3, and 19.3% for circular, rectangular , and square sections respectively. With increasing length of the columns to L/d=10, further reductions in the settlement obtained of (27.1, 28.1, and 27.0%). Bearing capacity of the soil increased slightly with length of the stone columns. Almost all cross sectional shapes of the columns give bearing capacity about same. The increased in the bearing capacity of the treated soil with stone columns have L/d=2, not exceeded 10% for all sectional types. The average increments in bearing capacity when L/d=10 are 12 and 15% at settlement 50 and 100mm respectively. Insignificant changes in bearing capacity upon increasing length of columns from L/d=2 to 10 of maximum 5%. The plastic zone recedes with the increasing length of the stone columns. Finally, from the results obtained, it can be concluded that the stone columns shape has negligible effects on the settlement and bearing capacity of the soil.

Bearing Capacity Improvement of Shallow Foundations Using Cement-Stabilized Sand

2016 ◽  
Vol 723 ◽  
pp. 795-800 ◽  
Author(s):  
Habib Rasouli ◽  
Hana Takhtfirouzeh ◽  
Abbasali Taghavi Ghalesari ◽  
Roya Hemati
Keyword(s):  
Bearing Capacity ◽  
Soil Stabilization ◽  
Cement Content ◽  
Experimental Tests ◽  
Dry Weight ◽  
Soil Improvement ◽  
Reinforced Soil ◽  
Shallow Foundation ◽  
Engineering Properties ◽  
Suitable Material

In order to attain a satisfactory level of safety and stability in the construction of structures on weak soil, one of the best solutions can be soil improvement. The addition of a certain percentage of some materials to the soil may compensate for its deficiency. Cement is a suitable material to be used for stabilization and modification of a wide variety of soils. By using this material, the engineering properties of soil can be improved. In this study, the effect of soil stabilization with cement on the bearing capacity of a shallow foundation was studied by employing finite element method. The material properties were obtained by conducting experimental tests on cement-stabilized sand. Cement varying from 2% to 8% by soil dry weight was added for stabilization. The effect of reinforced soil block dimensions, foundation width and cement content were investigated. From the results, it can be figured out that by stabilizing the soil below the foundation to certain dimensions with the necessary cement content, the bearing capacity of the foundation will increase to an acceptable level.

scholarly journals Comparative Study between Silica Fume and Nano Silica Fume in Improving the Shear Strength and Collapsibility of Highly Gypseous Soil

2020 ◽  
Vol 27 (1) ◽  
pp. 72-78
Author(s):  
Ahmed Al-Obaidi ◽  
Marwa Al-Mukhtar ◽  
Omar Al-Dikhil ◽  
Saeed Hannona
Keyword(s):  
Shear Strength ◽  
Silica Fume ◽  
Friction Angle ◽  
Engineering Properties ◽  
Nano Silica ◽  
Direct Shear Tests ◽  
Apparent Cohesion ◽  
Gypsum Content ◽  
Wet Condition ◽  
Gypseous Soil

Soils with highly gypsum content signify known as soils that exhibit collapsibility and sudden failure when being submerged to wetting. Many of the constructions built on this soil showed cracked and/or collapsed at some parts as these soils immersed or leached with water. The utilization of extremely fine materials, for example, Microscale or Nanoscale, is generally utilized these days. This research compared the use of Silica fume (SF) (micro material) and Nano Silica fume (NSF) (Nanomaterial) to explore the capability of these very fine materials to mend the shear strength and collapsibility properties of highly gypseous soils. The soil as Poorly Graded Sand (SP) was used, with a gypsum amount equal to 62%. A succession of direct shear tests and double odometer tests were carried on dry and submarined specimens of soil at various percentages of SF and NSF. The obtained results indicate that mixing the highly gypseous soils with SF or NSF improved the engineering properties of these soils, especially for the wet condition. The average increment in apparent cohesion when adding SF (5-20) percentage varies between (140-310) % in dry soil and (20-40) % in soaked soil. Same results obtained when mixing the gypseous soils with (1-5) % of NSF. Also, the Nanomaterial provided an improvement of the friction angle in dry and submerged cases respectively. Considering that, the SF gives adverse results upon the friction angle of the soil. The SF and the NSF both condensed the dangers of gypseous soil collapsibility. Consequently, the use of NSF can be assertively suggested to improve the engineering characteristics of highly gypseous soils when compared with SF, where only mixing of 3% of NSF gives the best results.

scholarly journals Effects of Waste Glass Powder on the Geotechnical Properties of Loose Subsoils

2018 ◽  
Vol 4 (9) ◽  
pp. 2044 ◽  
Author(s):  
Muhammad Siyab Khan ◽  
Muhammad Tufail ◽  
Mateeullah Mateeullah
Keyword(s):  
Bearing Capacity ◽  
Glass Powder ◽  
Soft Soil ◽  
Geotechnical Properties ◽  
Engineering Properties ◽  
Optimum Dose ◽  
Dry Density ◽  
Shear Stresses ◽  
Local Soil ◽  
Powdered Glass

Foundation soils are most affected by different problems when it comes to the loose soil having low shear strength and bearing capacity. Failure of the soil with settlement and shear arises when the shear stresses in the soil exceed the limit. This study is keen to observe the effects of utilization of waste broken glass in the enhancement of Geotechnical properties of soil by performing different laboratory tests. Collection of the soil sample from was concluded from Pabbi, Peshawar, KPK, and Pakistan, which is a low strength soil, are also being called soft soil having low bearing capacity. Furthermore, this particular soil was needed to be enhanced. The physical, chemical and engineering properties of virgin soil were contemplated and the soil was treated with added substances of Glass Powder to stabilize the local soil. Addition of Glass Powder was finished in different proportions that are 4%, 8% and 12% etc. Performance of different tests as Gradation, Specific Gravity, Standard Proctor compaction, Atterberg Limits, Direct Shear, CBR and so forth were done. The results were concluded, based on the Glass Dust stabilization analysis. It was obtained that pulverized glass can be effectively used as a soil stabilizer as mainly the strength characteristics were observed to be valeted. The Results showed that the gradation of soil is narrow from the particle size analysis. Plasticity index (P.I), Liquid limit (L.L) and plastic limit (P.L) were decreased with the addition of Glass powder. The reason behind decreasing P.I is maybe the fact that the Glass powder is cohesionless. Ideal percentage of Glass Powder as a stabilizer is 8%. Such improvements included an achievement of the highest CBR obtained at the 4%, 8% and 12% of powdered glass content. The reason is that the glass is pozzolanic material when blended with soil gives additional strength. The achievement of the increasing rate of the values of angle of internal friction on 4% and 8% and decreasing rate of values obtained at 12% powdered glass substances. Cohesion rate decreases up to 8% and starts increasing at 12%. Maximum dry density increasing as the density of glass is higher than such soil and Optimum moisture content (OMC) is decreasing because of low absorption capacity of glass. The study showed that the best stabilizer for the case study (Pabbi, Peshawar) is the Glass Powder and the optimum dose is 8 %.

Effect of Cement Content on the Behavior of Dune Sand-Cement Admixtures

2013 ◽  
Vol 838-841 ◽  
pp. 697-700
Author(s):  
Olavo Francisco Santos ◽  
Francisco Lopes ◽  
Yuri Daniel Jatoba Costa ◽  
Carina Maia Lins Costa
Keyword(s):  
Cement Content ◽  
Friction Angle ◽  
Dry Mass ◽  
Northeastern Brazil ◽  
Triaxial Tests ◽  
Engineering Practice ◽  
Dune Sand ◽  
Dune Sands ◽  
Road Base ◽  
Engineering Problems

The dune sands of the coast of Rio Grande do Norte State, northeastern Brazil, have serious engineering problems, namely low bearing capacity for shallow foundations and are not suitable as material for sub-base and road base. The use of this material in engineering practice needs improvement of their geotechnical properties. This paper investigates the effect of adding Portland cement to stabilize dune sand from the region of Natal, Brazil. Undrained triaxial tests were carried out to evaluate the effect of cement content on the geotechnical behaviour of dune sand-cement admixtures. Tests with admixtures with cement contents of 2.5, 5 and 10% of the dry mass of soil were carried out. Results showed that soil cohesion increased with increasing cement content. The friction angle of the admixtures was lower than that of the uncemented sand for cement content of 2.5 and 5% while It was larger than that of the uncemented sand for cement content of 10%.

scholarly journals Improvement of Soft Soil Using Linear Distributed Floating Stone Columns under Foundation Subjected to Static and Cyclic Loading

2019 ◽  
Vol 5 (3) ◽  
pp. 702 ◽  
Author(s):  
Mahdi O Karkush ◽  
Anwar Jabbar
Keyword(s):  
Cyclic Loading ◽  
Bearing Capacity ◽  
Soft Soil ◽  
Friction Angle ◽  
Soil Improvement ◽  
Stone Columns ◽  
Stone Column ◽  
Column Material ◽  
Area Replacement Ratio ◽  
Static And Cyclic Loading

A stone column is one of the soil improvement methods that are mainly used for improving the geotechnical behavior of soft soils. For deep improvement of soft soil, the floating stone columns are considered the best and effective economically which provide lateral confinement and drainage and longitudinal skin friction. In this study, six tests were carried out on the natural soft soil of undrained shear strength of 5.5 kPa improved by single and two linear distributed floating stone columns. The stone column dimensions are 30 mm in diameter and 180 mm in length and the stone column material is sand of high internal friction angle of 48°. The natural and improved soil samples are tested under isolated raft foundation of dimensions 120×120 mm subjected to vertical static and cyclic loading of frequency 2Hz and continued for 50 seconds. The results showed a significant improvement in soil bearing capacity when reinforced with stone columns despite the small area replacement ratio, where the bearing capacity of improved soil increased by 120 to 145%. The compressibility of improved soil decreased by 57 to 86% in comparison with that of natural soft soil. Also, the floating stone columns reduced the porewater pressure, where the stone columns considered efficient in providing short drainage pathways. This can be one of the reasons why soil reinforced with floating stone columns hold higher cyclic and static stresses regardless the end bearing of stone columns.

scholarly journals Experimental Study on Soil Stabilization Using Fibres

2021 ◽  
Keyword(s):  
Experimental Study ◽  
Bearing Capacity ◽  
Soil Stabilization ◽  
Soft Soil ◽  
Soil Samples ◽  
Engineering Properties ◽  
Soil Tests ◽  
Fine Grained ◽  
Fine Grained Soil ◽  
Materials Used

Abstract. For pavement constructions such as runway and highway construction, fine-grained soils are not suitable because of their undesirable properties such as grading of particle size, low bearing capacity, and more plasticity, and its ability to swell. To improve these soil properties various soil stabilization methods are needed. The stabilization is done by adding various stabilizing materials with the fine-grained soil. Fibres are one of the materials used in soil stabilization. This experimental study has been carried over to improve the bearing capacity of soft soil (from Sholinganallur, Chennai) by using Natural and Artificial fibres. During this study, the soil samples which has been stabilized with various fibres was prepared i.e., soil with Natural fibres (jute fibre) and soil with artificial fibres. In this experimental study, index properties and engineering properties of soft soil or unreinforced samples and stabilized soil samples with fibres are determined. Samples are subjected to various soil tests which have been used to determine the engineering properties of soil. The soil tests such as the standard proctor compaction test, unsoaked California Bearing Ratio (CBR) test, and Unconfined Compression (UCC) test had been done to determine the characteristics of the samples. To determine the properties of the reinforced materials, the fibres also have undergone various geosynthetic laboratory tests. The results of the study show that the bearing capacity of Shollinganallur fine-grained soil can be improved subsequently and water absorption by soil has been reduced significantly by using fibres.

scholarly journals Effects of Different Types of Fibers on the Physical and Mechanical Properties of MICP-Treated Calcareous Sand

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 268
Author(s):  
Jitong Zhao ◽  
Huawei Tong ◽  
Yi Shan ◽  
Jie Yuan ◽  
Qiuwang Peng ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Water Absorption ◽  
Glass Fiber ◽  
Physical And Mechanical Properties ◽  
Polyester Fiber ◽  
Engineering Properties ◽  
Fiber Types ◽  
Calcite Precipitation ◽  
Calcareous Sand ◽  
Hemp Fiber

Microbial-induced calcite precipitation (MICP) has been a promising method to improve geotechnical engineering properties through the precipitation of calcium carbonate (CaCO3) on the contact and surface of soil particles in recent years. In the present experiment, water absorption and unconfined compressive strength (UCS) tests were carried out to investigate the effects of three different fiber types (glass fiber, polyester fiber, and hemp fiber) on the physical and mechanical properties of MICP-treated calcareous sand. The fibers used were at 0%, 0.10%, 0.15%, 0.20%, 0.25%, 0.30%, 0.35%, and 0.40% relative to the weight of the sand. The results showed that the failure strain and ductility of the samples could be improved by adding fibers. Compared to biocemented sand (BS), the water absorption of these three fiber-reinforced biocemented sands were, respectively, decreased by 11.60%, 21.18%, and 7.29%. UCS was, respectively, increased by 24.20%, 60.76%, and 6.40%. Polyester fiber produced the best effect, followed by glass fiber and hemp fiber. The optimum contents of glass fiber and polyester fiber were 0.20% and 0.25%, respectively. The optimum content of hemp fiber was within the range of 0.20–0.25%. Light-emitting diode (LED) microscope and scanning electron microscope (SEM) images lead to the conclusion that only a little calcite precipitation had occurred around the hemp fiber, leading to a poor bonding effect compared to the glass and polyester fibers. It was therefore suggested that polyester fiber should be used to improve the properties of biocemented sand.

scholarly journals Experimental Study on Improvement of Marine Soft Soil with Alkali Residue

2018 ◽  
Vol 53 ◽  
pp. 04021
Author(s):  
SHAO Yong ◽  
LIU Xiao-li ◽  
ZHU Jin-jun
Keyword(s):  
Experimental Study ◽  
Compressive Strength ◽  
Unconfined Compressive Strength ◽  
Void Ratio ◽  
Soft Soil ◽  
Compressive Modulus ◽  
Engineering Properties ◽  
Test Results ◽  
Use Of Resources ◽  
One Year

Industrial alkali slag is the discharge waste in the process of alkali production. About one million tons of alkali slag is discharged in China in one year. It is a burden on the environment, whether it is directly stacked or discharged into the sea. If we can realize the use of resources, it is a multi-pronged move, so alkali slag is used to improve solidified marine soft soil in this paper. The test results show that the alkali residue can effectively improve the engineering properties of marine soft soil. Among them, the unconfined compressive strength and compressive modulus are increased by about 10 times, and the void ratio and plasticity index can all reach the level of general clay. It shows that alkali slag has the potential to improve marine soft soil and can be popularized in engineering.

scholarly journals Stabilization of Algerian Clayey Soils with Natural Pozzolana and Lime

2017 ◽  
Author(s):  
Khelifa Harichane ◽  
Mohamed Ghrici ◽  
Said Kenai
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Friction Angle ◽  
Internal Friction Angle ◽  
Plasticity Index ◽  
Engineering Properties ◽  
High Plasticity ◽  
Expansive Clay ◽  
Clayey Soils ◽  
Natural Pozzolana

Cohesive soils with a high plasticity index present difficulties in construction operations because they usually contain expansive clay minerals. However, the engineering properties of soils can be improved by different techniques. The aim of this paper is to study the effect of using lime, natural pozzolana or a combination of both lime and natural pozzolana on plasticity, compaction and shear strength of two clayey soils classified as CH and CL according to the unified soil classification system (USCS). The obtained results indicated that for CH class clay soil, the plasticity index decreased significantly for samples stabilized with lime. On the other hand, for the soil classified as CL class clay, a high decrease in the plasticity index value was observed for samples stabilized with natural pozzolana compared to those stabilized with lime. Also, both the cohesion and internal friction angle in lime added samples were demonstrated to increase with time. The combination of lime and natural pozzolana exhibits a significant effect on the enhancement of both the cohesion and  internal friction angle at later stages. The lime-natural pozzolana combination appears to produce higher shear strength parameters than lime or natural pozzolana used alone.

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