Influence of Water Content on Dynamic Elastic Modulus of Concrete

2013 ◽  
Vol 351-352 ◽  
pp. 1605-1609
Author(s):  
Fang Zhi Zhu ◽  
Tie Jun Zhao ◽  
Ting Guan
Keyword(s):  
Elastic Modulus ◽  
Water Content ◽  
Damage Assessment ◽  
Dynamic Elastic Modulus ◽  
Bending Vibration ◽  
Assessment Index ◽  
Content Change ◽  
Influence Of Water ◽  
Set Up ◽  
Low Sensitivity

Water content is one of key effect factors on the dynamic elastic modulus, which is an important damage assessment index of concrete structures induced by freeze-thaw cycles, fire and chemical attacks. Through the ultrasonic and bending vibration test, the regularity of dynamic elastic modulus changed with the water content of concrete specimens was analyzed in this paper. The results show that the ultrasonic velocity has a low sensitivity to water content when it is below 1.5%. The bending vibration method can better reflect the effect of water content change on dynamic elastic modulus. The regression equation of dynamic elastic modulus and water content was set up by introducing the index function. The research results offer technical reference for the predicting of actual concrete dynamic elastic modulus in different humidity environment.

scholarly journals Experimental Investigation on the Influence of Water Content on the Mechanical Properties of Coal under Conventional Triaxial Compression

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Meichang Zhang ◽  
Rongshan Nie
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Internal Friction ◽  
Water Content ◽  
Triaxial Compression ◽  
Friction Angle ◽  
Conventional Triaxial Compression ◽  
Influence Of Water ◽  
Confining Pressures ◽  
Water Contents

The presence of water is one of the most important factors in coal mining, and it has a dual influence on the mechanical behavior of rock. To study the influence of water content on the mechanical properties of coal under complicated stress conditions, dry coal specimens and wet coal specimens with water contents of 1.8% and 3.6% were conducted by uniaxial and conventional triaxial compression tests. The relations between the uniaxial compressive strength, deformation, and water content were observed. The reductions in the strength and elastic modulus under different confining pressures were obtained. The mechanical properties of coal specimens with different water contents under triaxial compression were studied. The influences of water content on the microstructure, clay minerals, internal friction angle, and cohesive force of coal were discussed. The results show that the strengths and elastic moduli of wet specimens are clearly lower than those of dry specimens under different confining pressures. The water content has a significant influence on the postfailure mechanical behavior of coal. The loss rates of strength and elastic modulus decrease with increasing confining pressure. The water content has almost no effect on the internal friction angle, while the cohesive force of the saturated specimens is 36.5% lower than that of the dry specimens. The results can provide a reference for inhibiting the occurrence of disasters during coal mining and exploiting coal efficiently.

scholarly journals Method Improvements of Testing Modulus of Soil Based on Free-Vibration Column

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Dandan Jin ◽  
Xianwen Huang ◽  
Binghui Wang ◽  
Aizhao Zhou ◽  
Shunqing Liu
Keyword(s):  
Elastic Modulus ◽  
Free Vibration ◽  
Small Strain ◽  
Dynamic Elastic Modulus ◽  
Dynamic Shear Modulus ◽  
Lateral Vibration ◽  
Bending Vibration ◽  
Vibration Equation ◽  
Testing Method ◽  
Displacement Sensors

It is difficult to directly measure the dynamic elastic modulus of soils when the strain is less than 10−4, though the dynamic shear modulus can be easily obtained by the free-vibration testing method. Some improvements were adapted to the traditional free-vibration column for measuring dynamic elastic modulus of soil precisely with lateral vibration in small strain (10−4∼10−6). Differing from the traditional lateral vibration theory, a new dynamic elastic modulus testing method based on bending vibration equation of cantilever beam was put forward based on the improved free-vibration column of GZZ-50. Firstly, some descriptions about calibration process of needed testing parameter (moment of inertia of drive board) were made, and then, Poisson’s ratio of standardized column was used to confirm the measured results. Four main improvements were applied, including the shape of drive board which made the bending vibration equation solved, laser displacement sensors for correcting specimen’s height parameter with uncontacted manner which can reduce the influence of specimen, a hoop with plug used to make the split mould be removed, and air duct used when installing drive board to increase the success rate of installing specimen. Finally, standard process of installing specimen was described, which can be used as reference of similar test.

A Novel AFM-MEA Platform for Studying the Real Time Mechano-Electrical Behavior of Cardiac Myocytes

2010 ◽  
Vol 1261 ◽  
Author(s):  
Jose Francisco Saenz Cogollo ◽  
Mariateresa Tedesco ◽  
Sergio Martinoia ◽  
Roberto Raiteri
Keyword(s):  
Elastic Modulus ◽  
Cardiac Myocytes ◽  
Electrical Response ◽  
Electrode Array ◽  
Maximum Load ◽  
Dynamic Elastic Modulus ◽  
Relaxation Cycle ◽  
Relaxation Phase ◽  
Cell Height ◽  
Set Up

AbstractWe present a novel experimental platform based on a combined Atomic Force Microscopy (AFM) and Micro-Electrode Array (MEA) set-up. We have used it to measure minimal changes in the morphological/mechanical properties of electrically active cell cultures as well as to measure the changes in the extracellular electrical activity when a single cell is stimulated by means of the AFM tip. In particular, we studied the dynamical changes in cell elasticity of embryonic rat cardiac myocytes along the contraction-relaxation cycle. Applying high load indentations, we also recorded the effects of mechanical stimulations on the cell electrophysiology. The dynamic elastic modulus of the cell related to the contraction-relaxation cycle reveals a temporal behavior that closely follows the changes in cell height. Observed values of dynamic elastic modulus at a maximum indentation depth of 1500nm varied between 8.93 ± 0.78 kPa during systolic (contraction) phase and 4.26 ± 0.47 kPa during diastolic (relaxation) phase. Induced electrophysiological responses were observed when applying loads in the range 40-150 nN. The probability P of recording an induced electrical response (P = 0.16 for a maximum load of 100nN) increased with the maximum applied load. Pulling-like stimulations due to the tip-cell adhesion could also evocate electrical responses.

Influence of Water Content on the Strength of Silt Soil in Yellow River Alluvial Plain

2012 ◽  
Vol 256-259 ◽  
pp. 481-487
Author(s):  
Xiao Ming Yi ◽  
Song Gen Wang ◽  
Zhen Qing Liu ◽  
Gang Xu
Keyword(s):  
Elastic Modulus ◽  
Water Content ◽  
Yellow River ◽  
Friction Angle ◽  
Cohesive Soil ◽  
High Water ◽  
Alluvial Plain ◽  
High Water Content ◽  
Optimum Water Content ◽  
Influence Of Water

Hydrophilic characteristic of silt soil in Yellow River alluvial plain was studied in order to reveal the water content changes of silt. Then strength tests were used to research how engineering parameters such as elastic modulus, cohesion and friction angle change at different water content. The results show that high permeability coefficient and strong capillary are main factors to increase the water content, and the influence of capillary rising is greater than that of rainfall infiltration. The strength characteristic of silt soil is similar to the character of non-cohesive soil in low water content and that of clay in high water content. If the water content is greater than optimum water content, the elastic modulus and cohesion of silt shall decay obviously. Friction angle decreases dramatically as well, when the soil is saturated.

Modeling the Influence of Water Content on Soil Vapor Extraction

2003 ◽  
Vol 2 (3) ◽  
pp. 368
Author(s):  
Hongkyu Yoon ◽  
Albert J. Valocchi ◽  
Charles J. Werth
Keyword(s):  
Water Content ◽  
Soil Vapor Extraction ◽  
Vapor Extraction ◽  
Influence Of Water

Study on mechanical properties and damage evolution of carbonaceous shale under triaxial compression with acoustic emission

2021 ◽  
pp. 105678952199119
Author(s):  
Kai Yang ◽  
Qixiang Yan ◽  
Chuan Zhang ◽  
Wang Wu ◽  
Fei Wan
Keyword(s):  
Mechanical Properties ◽  
Acoustic Emission ◽  
Water Content ◽  
Damage Evolution ◽  
Damage Assessment ◽  
Triaxial Compression ◽  
Confining Pressure ◽  
Damage Variable ◽  
Natural State ◽  
Carbonaceous Shale

To explore the mechanical properties and damage evolution characteristics of carbonaceous shale with different confining pressures and water-bearing conditions, triaxial compression tests accompanied by simultaneous acoustic emission (AE) monitoring were conducted on carbonaceous shale rock specimens. The AE characteristics of carbonaceous shale were investigated, a damage assessment method based on Shannon entropy of AE was further proposed. The results suggest that the mechanical properties of carbonaceous shale intensify with increasing confining pressure and degrade with increasing water content. Moisture in rocks does not only weaken the cohesion but also reduce the internal friction angle of carbonaceous shale. It is observed that AE activities mainly occur in the post-peak stage and the strong AE activities of saturated carbonaceous shale specimens appear at a lower normalized stress level than that of natural-state specimens. The maximum AE counts and AE energy increase with water content while decrease with confining pressure. Both confining pressure and water content induce changes in the proportions of AE dominant frequency bands, but the changes caused by confining pressure are more significant than those caused by water content. The results also indicate that AE entropy can serve as an applicable index for rock damage assessment. The damage evolution process of carbonaceous shale can be divided into two main stages, including the stable damage development stage and the damage acceleration stage. The damage variable increases slowly accompanied by a few AE activities at the first stage, which is followed by a rapid growth along with intense acoustic emission activities at the damage acceleration stage. Moreover, there is a sharp rise in the damage evolution curve for the natural-state specimen at the damage acceleration stage, while the damage variable develops slowly for the saturated-state specimen.

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