Factors affecting at-rest lateral stress in artificially cemented sands

1995 ◽  
Vol 32 (2) ◽  
pp. 195-203 ◽  
Author(s):  
Fanyu Zhu ◽  
Jack I. Clark ◽  
Michael J. Paulin
Keyword(s):  
Cement Content ◽  
Vertical Stress ◽  
Specimen Preparation ◽  
Test Results ◽  
Lateral Stress ◽  
Stress History ◽  
Cemented Sand ◽  
Vertical Loading ◽  
Cemented Sands ◽  
Dry Sand

This paper presents the results of a laboratory study on the at-rest lateral stress and Ko of two artificially cemented sands. A modified oedometer ring was used to measure the lateral stress of cemented and uncemented sands. Test materials were No. 3 Ottawa sand and a marine sand with Portland cement. The specimens were prepared using the method of undercompaction to minimize the influence of specimen preparation on test results. The cement contents were 0, 0.5, 1.0, 2.0, 4.0, and 8.0% by the weight of dry sand. The water content of the specimens was 4% of the weight of dry sand and cement. When the sands were cured under zero confining pressure, the test results indicated the following: the at-rest lateral stress in cemented sands decreases significantly with increasing cement content; the relationship between the vertical and at-rest lateral stress is nonlinear and the value of Ko increases with increasing vertical stress; and the lateral stress decreases with sand density and curing period. When the specimens were cured under vertical stress, the value of Ko during the removal of vertical loading increased with both overconsolidation ratio and cement content. Stress history has a significant influence on the behaviour of at-rest lateral stress in cement sands. Key words : cemented sand, Ko, lateral stress, overconsolidation, stress history.

Systematic Experimental Investigation of Dielectric Electroactive Polymers Using a Custom-Built Uniaxial Tensile Test Rig

2015 ◽  
Author(s):  
Micah Hodgins ◽  
Alexander York ◽  
Stefan Seelecke
Keyword(s):  
Pure Shear ◽  
Tensile Force ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Specimen Preparation ◽  
Testing Device ◽  
Test Results ◽  
Test Rig ◽  
Geometry Test

This work presents the design, fabrication and testing of a comprehensive DEAP test station. The tester is designed to perform tensile tests of planar DEAPs while measuring quantities such as tensile force, stretch, film thickness and voltage/current. The work details the specimen preparation and how the specimen is placed in the clamps. While the assembly process is performed by hand features were built-in to the design of the specimen frame and clamps to enable reliable placement and specimen geometry. Test results of the pure-shear specimen demonstrated good performance of the testing device. Although the electrode surface was rough the thickness stretch was evident during the stretching/actuation of the DEAP actuator.

Correlation between Unconfined Compressive Strength and Penetration Index Obtained from DCP Tests for Cemented Lateritic Soils

2019 ◽  
Vol 814 ◽  
pp. 399-403
Author(s):  
Anuchit Uchaipichat
Keyword(s):  
Compressive Strength ◽  
Unconfined Compressive Strength ◽  
Cement Content ◽  
Lateritic Soil ◽  
Test Results ◽  
Cone Penetration ◽  
Penetration Index ◽  
Curing Period ◽  
Cemented Soils ◽  
The Relationship

This paper presents the relationship between the dynamic cone penetration (DCP) test results and the unconfined compressive strength of lateritic cemented soils. A series of DCP tests and unconfined compressive strength was performed on lateritic cemented soil. The soils sample used in this study was lateritic soil. The test results for the DCP tests are presented in terms of penetration index. It can be observed that the penetration index decreased with increasing curing period and cement content. Moreover, the unconfined compressive strength of cemented soils increased with curing period and cement content. The relationship between unconfined compressive strength and penetration index is presented. A unique relationship for unconfined compressive strength can be obtained.

Characteristics of Films on the Surface of Sea Sand and Effects on the Dissolution of Chloride

2020 ◽  
Vol 842 ◽  
pp. 326-336
Author(s):  
Fei Long Sun ◽  
Shuai Wu ◽  
Quan Jiang ◽  
Huo Cheng Chen ◽  
Hong Yan Guan
Keyword(s):  
Chloride Content ◽  
Water Soluble ◽  
Hot Water ◽  
Water Extraction ◽  
New Method ◽  
Emission Spectrometry ◽  
Specimen Preparation ◽  
Test Results ◽  
Hot Water Extraction ◽  
Sea Sand

In this study, the effects of the specimen preparation method, temperature, and duration of the extraction step for the determination of the water-soluble chloride content of sea sand were investigated. The results demonstrated that increasing the heating temperature and duration promoted the dissolution of chloride, where the maximum value was obtained at 80°C and 60 min. Hot water extraction (80°C/60 min) could eliminate the effects of different specimen preparation methods on the final test results. Therefore, a new method was developed with drying at a temperature of 110 ± 5°C and hot water extraction at a temperature of 80°C for 60 min. The suitability of the new method for determining the water-soluble chloride content of sea sand was verified by testing the extracted specimens again. The results indicated that the chloride in sea sand dissolved fully with the new method, and thus it is suitable for testing the water-soluble chloride content of sea sand. Finally, the organic and inorganic compositions of the film adsorbed on the surface of sea sand were studied based on thermogravimetric analysis, inductively coupled plasma atomic emission spectrometry, ion chromatography, and total organic carbon measurements. The results indicated that a layer of substance (a multi-substance film) was adsorbed onto the surface of sea sand. This layer comprised inorganic salts (such as Cl–, Na+, Mg2+, SO42–, and Ca2+) and organic compounds, which were related to the composition of sea water. The multi-substance film greatly affected the dissolution and diffusion of chloride in the sea sand. Hot water extraction accelerated the dissolution of the film and increased the test results in terms of the water-soluble chloride contents.

Preliminary Development of Indirect Tensile Tester Cooperated with Industrial Computered Tomography for Asphalt Mixture

2010 ◽  
Vol 168-170 ◽  
pp. 2654-2657
Author(s):  
Xiao Jun Li ◽  
Li Hua Jiang ◽  
Yun Xian Wang
Keyword(s):  
Tensile Strength ◽  
Asphalt Concrete ◽  
Hoop Stress ◽  
Asphalt Mixture ◽  
Cylindrical Sample ◽  
Vertical Stress ◽  
Test Results ◽  
Tensile Tester ◽  
Indirect Tensile ◽  
Mixture Sample

In this paper, a new Indirect tensile tester (IDT) which can be cooperated with Industrial Computered Tomography (IDT) is developed. The new tester uses a set of sliders to transfer the vertical stress to hoop stress which applied to a hollow cylindrical sample. The micro-crack will be appeared and propagated in the weakest direction of hollow cylindrical sample with the increase of vertical stress and tensile strength can calculated with the maximum vertical stress. Due to the existence of central slider, the stress state of hollow cylindrical sample will be kept even after unloading and the mixture sample would not have recovery when it is moved for scanning with ICT. The test results show that the combination of the developed ICT with IDT will help obtain more useful information on understanding the nature of asphalt concrete with different tensile damage stages.

Effects of reinforcing elements on the behavior of weakly cemented sands

1988 ◽  
Vol 25 (2) ◽  
pp. 389-395 ◽  
Author(s):  
Loretta Li ◽  
Robert Mitchell
Keyword(s):  
Shear Strength ◽  
Key Words ◽  
Plane Strain ◽  
Failure Strain ◽  
Test Results ◽  
Cemented Sand ◽  
Mine Backfill ◽  
Unreinforced Material ◽  
Behavior Mining ◽  
Cement Mixture

Plane strain test results from weakly cemented sand samples with various types of reinforcement inclusions are reported. Mesh and anchored fibre types of reinforcements are shown to more than double the plane strain shear strength of a 33:1 sand–cement mixture. Other types of inclusions were not as effective, with some actually producing a strength decrease. All inclusions increased the ductility of this weakly cemented sand, allowing the material to absorb strains of 4–6% rather than the 0.5 – 1% of failure strain in the unreinforced material. The application of reinforcements to cemented tailings used for mine backfill is briefly discussed. Key words: reinforced backfill, cemented sand, behavior, mining.

Characterization of a cemented sand with the pulse-velocity method

2006 ◽  
Vol 43 (3) ◽  
pp. 294-309 ◽  
Author(s):  
Zahid Khan ◽  
Anwar Majid ◽  
Giovanni Cascante ◽  
D Jean Hutchinson ◽  
Parsa Pezeshkpour
Keyword(s):  
Compressive Strength ◽  
Water Content ◽  
Wave Velocity ◽  
Unconfined Compressive Strength ◽  
Void Ratio ◽  
Cement Content ◽  
Pulse Velocity ◽  
Initial Water Content ◽  
Strain Property ◽  
Cemented Sand

The effect of variation in cement content, initial water content, void ratio, and curing time on wave velocity (low-strain property) and unconfined compressive strength (large-strain property) of a cemented sand is examined in this paper. The measured pulse velocity is compared with predictions made using empirical and analytical models, which are mostly based on the published results of resonant column tests. All specimens are made by mixing silica sand and gypsum cement (2.5–20% by weight) and tested under atmospheric pressure. The wave velocity reaches a maximum at optimum water content, and it is mostly affected by the number of cemented contacts; whereas compressive strength is governed not only by the number of contacts but also by the strength of contacts. Experimental relationships are developed for wave velocity and unconfined compressive strength as functions of cement content and void ratio. Available empirical models underpredict the wave velocity (60% on average), likely because of the effect of microfractures induced by confinement during the testing. Wave velocity is found to be a good indicator of cement content and unconfined compressive strength for the conditions of this study.Key words: wave velocity, low-strain stiffness, cemented sands, elastic moduli, unconfined compressive strength.

Fluidity and Mechanical Behavior of Cement Solidified Lead-Zinc Mine Tailings

2014 ◽  
Vol 898 ◽  
pp. 383-386 ◽  
Author(s):  
Chun Lei Zhang ◽  
Shun Cai Wang ◽  
Fan Lu Min
Keyword(s):  
Mine Tailings ◽  
Cement Content ◽  
Strength Increase ◽  
Cemented Paste Backfill ◽  
Curing Time ◽  
Test Results ◽  
The World ◽  
Paste Backfill ◽  
Lead Zinc ◽  
Zinc Mine

Cemented paste backfill method has been widely used in many modern mines throughout the world due to the increasingly stringent environmental regulations and short of disposal land. This study presents experimental results on the use of Portland cement in the solidification of Pb-Zn tailings in China. Test results show UCS strength increase lineally with cement content, tailings concentration, and curing time, respectively. There exist a minimum cement content and tailings concentration to produce obvious strength. The fluidity decrease quickly with cement proportion and tailings concentration, under the satisfying of a minimum pumping fluidity, the increase of tailings concentration can effectively reduce the cement consumption so as to decrease the treatment cost.

Adiabatic Temperature Rise of Incompletely Hydrated Cement Concrete

2008 ◽  
Vol 400-402 ◽  
pp. 157-162 ◽  
Author(s):  
P.L. Ng ◽  
I.Y.T. Ng ◽  
A.K.H. Kwan
Keyword(s):  
Temperature Rise ◽  
Cement Content ◽  
High Strength ◽  
Adiabatic Temperature ◽  
Test Method ◽  
Experimental Program ◽  
Test Results ◽  
Prediction Formula ◽  
Adiabatic Temperature Rise ◽  
Water Contents

The temperature rise of concrete during hardening is intimately related to the mix proportion, among which the cement content is a major factor. However, high-strength concrete mixes are often proportioned with low water contents which leads to incomplete hydration of cement contained therein. Hence, the conventional rule of determining concrete temperature rise solely based on the cement content may not yield accurate estimations. An experimental program has been launched to investigate the coupled effects of cement and water contents on the adiabatic temperature rise of concrete. Eighteen concrete mixes were tested with a newly developed semi-adiabatic curing test method and their adiabatic temperature rise obtained by applying heat loss compensation to the test results. The results revealed that, when the water/cement ratio is lower than 0.36, both cement and water contents have effects on the adiabatic temperature rise of concrete. Prediction formula and design chart of adiabatic temperature rise, which are accurate to ±1.3°C compared with the test results, are developed. Furthermore, prediction formula of the degree of hydration of concrete is recommended.

scholarly journals Effects of Crumb Rubber on Compressive Strength of Cement-Treated Soil

2015 ◽  
Vol 61 (4) ◽  
pp. 59-78 ◽  
Author(s):  
F. C. Wang ◽  
W. Song
Keyword(s):  
Compressive Strength ◽  
Cement Content ◽  
Rubber Particle ◽  
Crumb Rubber ◽  
Test Results ◽  
Rubber Content ◽  
Strength Tests ◽  
Strength And Stiffness ◽  
Cement Soil ◽  
Curing Age

A study was undertaken to investigate the effects of crumb rubber on the strength and mechanical behaviour of Rubberized cement soil (RCS). In the present investigation, 26 groups of soil samples were prepared at five different percentages of crumb rubber content, four different percentages of cement content and two different finenesses of crumb rubber particle. Compressive strength tests were carried out at the curing age of 7 days, 14 days, 28 days and 90 days. The test results indicated that the inclusion of crumb rubber within cement soil leads to a decrease in the compressive strength and stiffness and improves the cement soil’s brittle behaviour to a more ductile one. A reduction of up to 31% in the compressive strength happened in the 20% crumb content group. The compressive strength increases with the increase in the cement content. And the enlargement of cement content is more efficient at low cement content.

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