scholarly journals Laboratory Study on Improvement of Expansive Soil by Chemically Induced Calcium Carbonate Precipitation

Materials ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3372
Author(s):  
Shaoyang Han ◽  
Baotian Wang ◽  
Marte Gutierrez ◽  
Yibo Shan ◽  
Yijiang Zhang
Keyword(s):  
Calcium Carbonate ◽  
Model Test ◽  
Expansive Soil ◽  
Laboratory Scale ◽  
Scale Model ◽  
Swelling Ratio ◽  
Direct Shear ◽  
Unconfined Compression ◽  
Precipitation Technique ◽  
Free Swell

This paper proposes the use of calcium carbonate (CaCO3) precipitation induced by the addition of calcium chloride (CaCl2) and sodium carbonate (Na2CO3) solutions as a procedure to stabilize and improve expansive soil. A set of laboratory tests, including the free swell test, unloaded swelling ratio test, unconfined compression test, direct shear test, scanning electron microscopy (SEM) test, cyclic wetting–drying test and laboratory-scale precipitation model test, were performed under various curing periods to evaluate the performance of the CaCO3 stabilization. It is concluded from the free swell tests and unloaded swelling ratio tests that the addition of CaCl2 and Na2CO3 can profoundly decrease soil expansion potential. The reduction in expansion parameters is primarily attributed to the strong short-term reactions between clay and stabilizers. In addition, the formed cementation precipitation can decrease the water adsorption capacity of the clay surface and then consequently reduce the expansion potential. The results of unconfined compression tests and direct shear strength tests indicated that the addition of CaCl2 and Na2CO3 has a major effect on geotechnical behavior of expansive soils. Based on the SEM analyses, new cementing crystalline phases formatted by sequentially mixing CaCl2 and Na2CO3 solutions into expansive soil were found to appear in the pore space, which results in a much denser microstructure. A laboratory-scale model test was conducted, and results demonstrate the effectiveness of the CaCO3 precipitation technique in stabilizing the expansive soil procedure. The test results indicated that the concentration of CaCl2 higher than 22.0% and Na2CO3 higher than 21.2% are needed to satisfactorily stabilize expansive soil. It is proposed to implement the precipitation technique in the field by the sequential permeation of CaCl2 and Na2CO3 solutions into soils in situ.

scholarly journals Plasticity, Swell-Shrink, and Microstructure of Phosphogypsum Admixed Lime Stabilized Expansive Soil

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Jijo James ◽  
P. Kasinatha Pandian
Keyword(s):  
Industrial Waste ◽  
Expansive Soil ◽  
Liquid Limit ◽  
Unconfined Compression ◽  
Plastic Limit ◽  
Unconfined Compression Test ◽  
Microstructural Study ◽  
Stabilized Soil ◽  
Free Swell ◽  
Index Tests

The study involved utilization of an industrial waste, Phosphogypsum (PG), as an additive to lime stabilization of an expansive soil. Three lime dosages, namely, initial consumption of lime (ICL), optimum lime content (OLC), and less than ICL (LICL), were identified for the soil under study for stabilizing the soil. Along with lime, varying doses of PG were added to the soil for stabilization. The effect of stabilization was studied by performing index tests, namely, liquid limit, plastic limit, shrinkage limit, and free swell test, on pulverized remains of failed unconfined compression test specimens. The samples were also subjected to a microstructural study by means of scanning electron microscope. Addition of PG to lime resulted in improvement in the plasticity and swell-shrink characteristics. The microstructural study revealed the formation of a dense compact mass of stabilized soil.

Settlement characteristics of bridge approach embankment based on scale model test

2020 ◽  
Vol 27 (7) ◽  
pp. 1956-1964
Author(s):  
Jiu-peng Zhang ◽  
Tao Liu ◽  
Jian-zhong Pei ◽  
Rui Li ◽  
Dao-guang Zou ◽  
...  
Keyword(s):  
Model Test ◽  
Scale Model ◽  
Bridge Approach

scholarly journals Scaling for lobe and cleft patterns in particle-laden gravity currents

2013 ◽  
Vol 20 (1) ◽  
pp. 121-130 ◽  
Author(s):  
A. Jackson ◽  
B. Turnbull ◽  
R. Munro
Keyword(s):  
Granular Material ◽  
Froude Number ◽  
Particle Diameter ◽  
Granular Flows ◽  
Leading Edge ◽  
Air Entrainment ◽  
Gravity Currents ◽  
Laboratory Scale ◽  
Scale Model ◽  
Snow Avalanches

Abstract. Lobe and cleft patterns are frequently observed at the leading edge of gravity currents, including non-Boussinesq particle-laden currents such as powder snow avalanches. Despite the importance of the instability in driving air entrainment, little is known about its origin or the mechanisms behind its development. In this paper we seek to gain a better understanding of these mechanisms from a laboratory scale model of powder snow avalanches using lightweight granular material. The instability mechanisms in these flows appear to be a combination of those found in both homogeneous Boussinesq gravity currents and unsuspended granular flows, with the size of the granular particles playing a central role in determining the wavelength of the lobe and cleft pattern. When scaled by particle diameter a relationship between the Froude number and the wavelength of the lobe and cleft pattern is found, where the wavelength increases monotonically with the Froude number.

scholarly journals Shear strength characteristics of Jerash expansive soil

2021 ◽  
Vol 3 (2) ◽  
pp. 74-80
Author(s):  
Talal Masoud
Keyword(s):  
Shear Strength ◽  
Internal Friction ◽  
Water Content ◽  
Direct Shear Test ◽  
Shear Test ◽  
Expansive Soil ◽  
Content Increase ◽  
Direct Shear ◽  
Initial Water ◽  
Angle Of Internal Friction

The results of the direct shear test on Jerash expansive soil show the effect of the initial water content on the cohesion (c) and on the angel of internal friction ( ) [shear strength parameters].it show that, as the initial water increase, the cohesion (c) of Jerash expansive soil also increase up to the shrinkage limit, after that increase of water even small amount, decrease the cohesion of the soil. On the other hand, the results of direct shear test show also  that as the water content increase, the angle of internal friction ( )remain unchanged up to shrinkage limit , any increase of water cause a large decrease on the angle of internal friction of Jerash expansive soil.

scholarly journals Identification of a Suitable Solid Carrier as a Matrix for the Permeable Reactive Barrier of Laboratory Scale Model Aquifer for Atrazine Degradation

1970 ◽  
Vol 25 (1) ◽  
pp. 119-128 ◽  
Author(s):  
Binita K Shrestha ◽  
Pawan Raj Shakya ◽  
MIM Soares
Keyword(s):  
Laboratory Scale ◽  
Permeable Reactive Barrier ◽  
Scale Model ◽  
Pseudomonas Sp ◽  
Reactive Barrier ◽  
Solid Carrier ◽  
Different Types ◽  
Simultaneous Loss ◽  
Static Conditions ◽  
Atrazine Degradation

Three different types of physical substrata such as sand, granualar activated carbon (GAC) and plastic macaroni beads were selected to identify a suitable solid carrier as a course matrix for the permeable reactive barrier (PRB) in a sand filled two-dimensional laboratory-scale model aquifer. An adhesion experiment was performed and tested with Pseudomonas sp ADP (PASP) under agitated as well as static conditions. In static conditions, adhesion to GAC was the highest (80%) followed by that to beads (60%). No adhesion to sand was observed under static or agitated conditions. Since atrazine is adsorbed by GAC, its bioavailability for degradation by PADP may be affected. To test this, simultaneous loss of atrazine and release of chloride (dechlorination, the first step in the pathway of atrazine degradation by PADP) were determined in the presence and absence of GAC. Although cells remained viable, no significant chloride release was detected. Thus, plastic macaroni beads were identified and selected as the most suitable support for PADP in the biological permeable reactive barrier (BPRB) of the model aquifer.Key words: Suitable Solid; Laboratory Scale; PADPTribhuvan University JournalVol. XXV, No. 1, 2005Page:119-128Uploaded date: 26, September, 2010

scholarly journals Investigation of Deformation of Shield Tunnel Based on Large-scale Model Test

2020 ◽  
Vol 61 (1) ◽  
pp. 16-21
Author(s):  
Kiwamu TSUNO ◽  
Kaho KINOSHITA ◽  
Takashi USHIDA
Keyword(s):  
Model Test ◽  
Large Scale ◽  
Scale Model ◽  
Shield Tunnel ◽  
Large Scale Model

scholarly journals Strength benefit of sawdust/wood ash amendment in cement stabilization of an expansive soil

2019 ◽  
Vol 28 (50) ◽  
pp. 44-61 ◽  
Author(s):  
Jijo James
Keyword(s):  
Expansive Soil ◽  
Experimental Program ◽  
Unconfined Compression Strength ◽  
Strength Gain ◽  
Unconfined Compression ◽  
Saw Dust ◽  
Strength Based ◽  
Cement Stabilization ◽  
Early Strength ◽  
Pavement Thickness

The investigation evaluated the strength benefits obtained by amending cement stabilization of an expansive soil by using saw dust ash (SDA), a waste generated in wood milling industries due to burning. The experimental program involved the preparation of cylindrical specimens of size 38 mm x 76mm for evaluating the unconfined compression strength (UCS) of the cement stabilized and amended samples cured for varying periods of 2 hours, 7, 14 and 28 days. Two cement contents of 2% and 6% by weight of soil were adopted to stabilize the soil. The SDA amended cement stabilized samples adopted SDA contents of 5%, 10% and 20% by weight of soil. Strength gain trends for the amended samples were also fitted based on the results of the UCS tests. In order to analyse benefits in pavement design and thickness reduction, the UCS values were used to predict the CBR value of the specimens based on which the reduction in pavement thickness was calculated for different traffic densities. The investigation revealed that 5% SDA amendment of cement stabilization can result in up to 26% increase in early strength and 20% increase in delayed strength. Based on the predicted CBR values, pavement thickness can be reduced up to 8.3%.

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