scholarly journals Intercalation and calcination as methods to reduce expansive soil properties

2021 ◽  
Vol 18 (1) ◽  
pp. 36
Author(s):  
Ristiya Adi Wiratama ◽  
Eko Hanudin ◽  
Benito Heru Purwanto
Keyword(s):  
Crack Width ◽  
Expansive Soil ◽  
Treatment Method ◽  
Exchange Capacity ◽  
Expansive Clay ◽  
Average Crack ◽  
Interlayer Structure ◽  
The Stability ◽  
Swelling Volume ◽  
Calcination Treatment

The expansive ability of soil causes a series of problems in various sectors. The dominance of smectite clay minerals significantly affects expansive ability because they have an unstable interlayer structure. Cation intercalation and calcination is a treatment method that can increase the stability of the clay interlayer structure. This research investigated the effects of intercalation cations and calcination treatment on the swelling ability and cracking properties in the clay from vertisols; the cations used for intercalation were aluminum and iron. The intercalation tested doses were based on the equivalent weight of 0x, 0.5x, and 1x cation exchange capacity (CEC) clay value. The calcination treatments used were 200°C, 300°C, and no calcination. Each treatment interaction was repeated three times. Parameters observed were the total area, average crack width, average lump area, total number of lumps, moisture content, swelling volume, and pH after treatment. The results showed that each treatment had a significant effect. Clay with an Al intercalation dose of 1x CEC without calcination treatment had the highest total area after drying, which was 41.035 cm<sup>2</sup>; the lowest average crack width was 0.153 cm, and the smallest swelling volume was 3.6 cm<sup>3</sup>. In contrast, the clay without intercalation and calcination treatments had a swelling volume up to 10 cm<sup>3</sup> on the 7<sup>th</sup> day. The clay with an Al intercalation dose of 1x CEC with 200°C calcination exhibited the best results in reducing the expansive clay ability and can be used as a guideline for further testing to reduce the soil’s expansive ability.

Compressibility and hydraulic conductivity of a chemically treated expansive clay

2001 ◽  
Vol 38 (1) ◽  
pp. 154-160 ◽  
Author(s):  
Zalihe Nalbantoglu ◽  
Erdil Riza Tuncer
Keyword(s):  
Fly Ash ◽  
Hydraulic Conductivity ◽  
Expansive Soil ◽  
Dry Weight ◽  
Pozzolanic Reaction ◽  
Exchange Capacity ◽  
Expansive Clay ◽  
Preconsolidation Pressure ◽  
Few Data ◽  
Published Research

The paper presents a series of laboratory tests and evaluates the effect of lime and fly ash on the compressibility and hydraulic characteristics of an expansive soil in Cyprus. The tests were performed at different percentages of lime (0–7%) and fly ash (15 and 25%) by dry weight of soil, and additional tests were also performed on soils treated with 15% fly ash plus 3% lime. Previously published research reveals that few data are available concerning the compressibility and hydraulic conductivity of lime-treated soils. The results of this study indicate an increase in the vertical effective yield stress (apparent preconsolidation pressure) and a decrease in the compressibility characteristics of the treated soils. Moreover, unlike some of the findings in the literature, higher hydraulic conductivity values were obtained with time. This finding has been substantiated by the reduced cation exchange capacity (CEC) values, which indicate that the pozzolanic reaction causes the soils to become more granular in nature, resulting in higher hydraulic conductivity.Key words: cementation, compressibility, fly ash, hydraulic conductivity, lime.

Indoor Experimental Research on the Unconfined Compressive Strength of Lime Improving Expansive Clay

2011 ◽  
Vol 250-253 ◽  
pp. 2296-2301
Author(s):  
Ai Jun Chen ◽  
Jia Sheng Zhang ◽  
Li Ying Peng ◽  
Zhen Hua Ren
Keyword(s):  
Compressive Strength ◽  
Experimental Research ◽  
Unconfined Compressive Strength ◽  
Expansive Soil ◽  
Linear Increase ◽  
Expansive Clay ◽  
Curing Time ◽  
Guangxi Province ◽  
Strength Index ◽  
The Stability

Guangxi province is the typical expansive soil area, and the unconfined compressive strength is the important strength index. There is little studied result about the unconfined compressive strength of expansive soil in Guangxi province. Based on the expansive clay experimental embankment of Nanyou Highway, the experimental research on the unconfined compressive strength was undertaken. Tests results indicate that the expansive clay samples are all disintegrated when the sample is dip in water, which show that the stability of expansive clay is very weak. Some lime improving samples of curling 7 days and 14 days are also disintegrated when dipping in water, which indicate that the unconfined compressive strength sample of lime improving expansive clay should curl 28 days. Lime ratio and curing time both influence the unconfined compressive strength of improving expansive clay greatly. There is optimum adding lime ratio for lime improving expansive clay. During the early days of curing the unconfined compressive strength have linear increase with curing time.

scholarly journals Study on Hygroscopic Swelling and Dehumidification Cracking Characteristics of Expansive Soil under Acid Rain and Cyclic Drying-Wetting

2021 ◽  
Vol 2021 ◽  
pp. 1-10
Author(s):  
Jin Chang ◽  
Jie Xiao ◽  
Jian-Qing Jiang ◽  
Rui Zhang ◽  
Xi-Long Kuang ◽  
...  
Keyword(s):  
Acid Rain ◽  
Crack Width ◽  
Digital Camera ◽  
Expansive Soil ◽  
Crack Development ◽  
High Definition ◽  
Ph Values ◽  
Swelling Rate ◽  
Cracking Characteristics ◽  
Average Crack

In this study, to reveal the swelling and cracking characteristics of expansive soil subjected to cyclic drying-wetting of acid rain, the effects of acid rain and cyclic drying-wetting on the swelling deformation of expansive soil were studied by using the load-free swelling rate test. Afterward, a high-definition digital camera was used to capture the crack development images of the sample during the dehumidification process under cyclic drying-wetting of acid rain. Furthermore, the changes of the microstructure and mineral composition of the expansive soil after cyclic drying-wetting of acid rain were analyzed by using the scanning electron microscopy (SEM) and X-ray diffraction (XRD) tests. Finally, the effect mechanisms of acid rain and cyclic drying-wetting on the swelling deformation and crack development of the expansive soil were discussed. The results indicate that acid rain has a positive effect on the swelling deformation and crack development of the expansive soil. The effect is greater with a stronger acidity of rainfall. Moreover, the combined action of acid rain and cyclic drying-wetting can promote the swelling deformation and crack development of the sample more notably. The swelling rate of the sample increased most significantly during the first two-time cyclic drying-wetting. The measured swelling rates at pH = 3 and 5 are 23.7% and 20.6%, respectively, which are higher than the swelling rates of 19.0% at pH = 7. The humidity of samples is 17–18% after the first-time drying-wetting cycle. The crack area ratios (Mf) of the samples with pH values of 5 and 3 are, respectively, increased by 11.0% and 69.1%; the average crack width of the sample increases by 32.3% and 93.3%, respectively, compared with pH values of 7. After the fourth-time drying-wetting cycle, Mf and the average crack width of the samples under the rainwater environment of three pH values increase greatly, but the difference of Mf among them became unapparent. In addition, the microscopic test results show that acid rain can corrode the binding materials (e.g., SiO2, Al2O3, K2O, MgO, and CaO) in the expansive soil. The erosion of the binding minerals weakens the structural connection strength, resulting in continuous increases in both size and number of microvoids. Under the superimposed influence of cyclic drying-wetting, the above changes are even more dramatic. Macroscopically, the swelling deformation of expansive soil increases and the cracks develop rapidly.

Research on the Ecological Protection Mechanism and Applied of Expansive Soil Slope

2014 ◽  
Vol 501-504 ◽  
pp. 359-367
Author(s):  
Feng Zhou ◽  
Kai Zhang ◽  
Ying Chun Tang
Keyword(s):  
Slope Failure ◽  
Expansive Soil ◽  
Treatment Method ◽  
Engineering Properties ◽  
Soil Slope ◽  
Protection Mechanism ◽  
Temperature Changes ◽  
Ecological Protection ◽  
Slope Treatment ◽  
Vegetation Formation

This paper summarizes and analyzes the basic concepts and ecological protection mechanism for expansion geotechnical slope failure mechanism and the resulting impact on the shallow, traction engineering properties such as analysis, proposed ecological slope of expansive soil slope mechanism of action: vegetation system by improving internal slope soil moisture and temperature changes affect the atmosphere and thus effectively reduce the depth. Vegetation root through reinforced anchoring, delay time and improving soil hydration ductility such as the role played good strength enhancement. Vegetation formation can effectively improve the damaged outer slope interface morphology, to restore the ecological environment and landscape effect. Integrating the past experience on expansive soil slope treatment, this paper provide a slope treatment method used in Nanning metro Tunli section, these will provide reference for the expansive soil slope ecological management.

scholarly journals Experimental Study on Dynamic Resilient Modulus of Lime-Treated Expansive Soil

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Zheng Lu ◽  
Yang Zhao ◽  
Shaohua Xian ◽  
Hailin Yao
Keyword(s):  
Moisture Content ◽  
Environmental Changes ◽  
Resilient Modulus ◽  
Expansive Soils ◽  
Expansive Soil ◽  
Confining Pressure ◽  
Triaxial Tests ◽  
The Stability ◽  
Compaction Degree

Dynamic resilient modulus is the design index of highway subgrade design code in China, which is significantly affected by the traffic loads and environmental changes. In this study, dynamic triaxial tests were conducted to investigate the influence of moisture content, compaction degree, cyclic deviator stress, and confining pressure on lime-treated expansive soil. The suitability of UT-Austin model to lime-treated expansive soils was verified. The results indicate that the dynamic resilient modulus of lime-treated expansive soils increases nonlinearly with the increase of compaction degree, while decreases nonlinearly with the increase of dynamic stress level. The dynamic resilient modulus decreases linearly with the increase of moisture content and increases linearly with the increase of confining pressure. Moreover, the moisture content has a more significant effect on the dynamic resilient modulus of lime-treated expansive soil. Therefore, it is necessary to ensure the stability of soil humidity state and its excellent mechanical properties under long-term cyclic loading for the course of subgrade filling and service. Finally, the calculated results of the UT-Austin model for dynamic resilient modulus show a good agreement with the test results.

Theoretical Analysis of Reinforced Beams of UHTCC

2018 ◽  
Vol 878 ◽  
pp. 18-22
Author(s):  
Hua Qiang Yu
Keyword(s):  
Crack Width ◽  
Approximate Formula ◽  
Crack Spacing ◽  
Cementitious Composite ◽  
Reinforcement Effect ◽  
Ordinary Concrete ◽  
High Toughness ◽  
Reinforced Beams ◽  
New Type ◽  
Average Crack

UHTCC (Ultra High Toughness Cementitious Composite) is a new type of material which is widely used in this study. It is a kind of cement-based material with very good toughness. It is effective to improve the performance of damaged reinforced concrete and improve its durability. UHTCC is widely used in the reinforcement of concrete structures. There is no clear and effective method for calculating it. There is an approximate formula for the crack width of ordinary concrete. The concept of an average crack spacing is used in the derivation of the formula. The limit of UHTCC for cracks can be measured by the concept of average crack spacing. According to the obtained crack width limit, the reinforcement effect of UHTCC can be shown.

scholarly journals Fine Exploration and Control of Subway Crossing Karst Area

2019 ◽  
Vol 9 (13) ◽  
pp. 2588 ◽  
Author(s):  
Jing Wang ◽  
Liping Li ◽  
Shaoshuai Shi ◽  
Shangqu Sun ◽  
Xingzhi Ba ◽  
...  
Keyword(s):  
Three Dimensional ◽  
Treatment Method ◽  
Surrounding Rock ◽  
Karst Area ◽  
Actual Situation ◽  
Construction Process ◽  
Tunnel Stability ◽  
Field Displacement ◽  
The Stability ◽  
And Control

A large number of subway projects need to cross all kinds of disaster sources during the construction process. When a disaster source is unknown and uncertain, it is difficult for tunnel stability analysis to conform to the actual situation, which is likely to cause serious geological disasters. Firstly, the accurate location of the source of the disaster is realized via the geophysical method, and the orientation of the target is determined. Secondly, real imaging of the geological disaster source is realized using fine three-dimensional scanning equipment. Finally, the coupling law of the seepage field, displacement field, and stress field of the tunnel surrounding rock are analyzed. The stability of the tunnel is analyzed, and the reasonable karst treatment method is put forward.

scholarly journals Analysis of Factors Influencing Stability of Overlying Soil Layer on Thin Bedrock Based on Crack Development-Closure Test

2019 ◽  
Vol 2019 ◽  
pp. 1-20 ◽  
Author(s):  
Guangming Wu ◽  
Haibo Bai ◽  
Luyuan Wu ◽  
Shixin He ◽  
Bin Du
Keyword(s):  
Water Content ◽  
Layer Thickness ◽  
Crack Width ◽  
Soil Layer ◽  
Crack Development ◽  
Sand Content ◽  
Particle Composition ◽  
Thin Bedrock ◽  
The Stability ◽  
Seam Mining

The water-blocking properties of the clay layer at the bottom of the Cenozoic overburden in China are an important factor influencing the safety of thin bedrock coal seam mining. Clay has remolding properties that are unlike the nonreversible characteristics of cracks in brittle rock, and failure cracks in clay can reclose or continue to expand under the influence of different external factors. In this work, the soil layer on top of thin bedrock is the research object, and the influences of the particle composition, water content, soil layer thickness, and crack width on the crack development-closure state of soil layer are analyzed by the orthogonal test method. Visual analysis shows that the order of influence of each factor on the stability of soil layer is the crack width, particle composition, soil layer thickness, and water content. The stability of soil layer decreases with increasing crack width and sand content and decreasing soil layer thickness; in addition, soil layer stability decreases first and then increases with increasing water content. Further variance analysis shows that the crack width and particle composition are key factors that impact the stability of soil layer and that the soil layer thickness has some influence, while the water content has little effect on the stability of soil layer. In addition, the crack will reclose when the sand content in soil is less than 50% and the crack width is less than or equal to 1.0 mm, and the soil layer is prone to further failure when the sand content in soil is more than 50% and the crack width is greater than or equal to 3.0 mm; when the soil layer thickness is 15.0 cm, its stability is better than when the soil layer thickness is 10.0 cm or 5.0 cm.

Mineralogical, physical and chemical investigation of compacted Kunigel V1 bentonite in contact with a steel heater in the ABM test package 1 experiment, Äspö laboratory, Sweden

Clay Minerals ◽  
2017 ◽  
Vol 52 (1) ◽  
pp. 127-141 ◽  
Author(s):  
H. Sasamoto ◽  
T. Isogai ◽  
H. Kikuchi ◽  
H. Satoh ◽  
D. Svensson
Keyword(s):  
Exchange Capacity ◽  
Exchangeable Cations ◽  
Exchangeable Cation ◽  
Exchange Reactions ◽  
Swelling Properties ◽  
X Ray ◽  
Set Up ◽  
The Stability ◽  
High Level ◽  
Physical And Chemical

AbstractIn many countries, compacted bentonite is a candidate engineering barrier material for safe disposal of high-level radioactive waste. The Swedish Nuclear Fuel and Waste Management Company (SKB) set up an in situ experiment (the ABM project) to compare the stability of different bentonites under the conditions of exposure to an iron source and to elevated temperature (up to 130°C) at the Äspö Hard Rock Laboratory, Sweden. Results for the Japanese bentonite (Kunigel V1) are summarized in the present study.Mineralogical investigation using X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) suggested no transformation of smectite or neoformed clay phases. However, a distinct change in exchangeable cations of smectite was indicated (i.e. from Na type to Fe type and/or Ca type) in the bentonite in the vicinity of the steel heater.Measurements of hydraulic conductivity and swelling properties suggest that no significant changes occurred in the bentonite even in the vicinity of the steel heater. This is attributed to the limited portion of the bentonite affected by the iron–bentonite interactions and the incomplete ion-exchange reactions. The methylene blue cation exchange capacity and the determination of the exchangeable cations showed that the lateral distribution for these parameters was constant. However, the total exchangeable cation population has changed significantly compared to the initial sample.

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