Comparing Tests on the Durability of Concrete after Long-Term Immersion in Different Salt Solution

2014 ◽  
Vol 501-504 ◽  
pp. 1087-1091 ◽  
Author(s):  
Xiao Ping Su ◽  
Li Zhang
Keyword(s):  
Elastic Modulus ◽  
Salt Solution ◽  
Saline Soil ◽  
Salt Water ◽  
Dynamic Elastic Modulus ◽  
Salt Crystallization ◽  
Soluble Salts ◽  
Concrete Damage ◽  
Damage Law

The western region of Jilin province is one of the areas with the most serious saline soil, which is the type of inland soda salt. In order to study the damage law of concrete under the condition of long-term erosion by the soluble salts in saline soil or groundwater or saturated salt water, three groups of salt solution, Na2SO4, NaCl, NaHCO3 solution, were made according to the content of soluble salts in saline soil of Daan city in spring, and water was as a comparison. The comparing tests of long-term immersion were conducted on the normal concrete specimens with the size of 40mm×40mm×160mm. The results show that there is little change on the appearance, mass and dynamic elastic modulus of concrete soaked in water. But for the concrete soaked in salt solution, the loss rate of mass changes from reduction to growth, the relative dynamic elastic modulus of concrete grows at first and declines later. Through analysis of electron microscope scanning, energy spectrum and chemical composition of concrete samples, concrete damage caused by salts includes chemical erosion and salt crystallization damage. Na2SO4 mainly influences the dynamic elastic modulus of concrete, NaCl mainly influences the mass of concrete due to its strong penetration, while NaHCO3, ranking between the two salts above, largely influences not only the mass of concrete, but also the dynamic elastic modulus of concrete.

Evaluating the Air-Entraining Concrete Performance Decay Rule under Long-Term Salts Corrosion Using MATLAB Software

2014 ◽  
Vol 1015 ◽  
pp. 124-128
Author(s):  
Xiao Ping Su ◽  
Hao Yue Sun
Keyword(s):  
Elastic Modulus ◽  
Linear Regression ◽  
Evaluation Model ◽  
Evaluation Index ◽  
Dynamic Elastic Modulus ◽  
Concrete Durability ◽  
Durability Test ◽  
Matlab Software ◽  
Concrete Damage

In the concrete salt-soaking durability test, the dynamic elastic modulus of concrete is more sensitive to the concrete damage than the mass, and can reflect the concrete durability better. In this paper,the relative dynamic elastic modulus of concrete is used as the evaluation index of concrete durability. Its attenuation law is made the multiple linear regression by using MATLAB software. The evaluation model and its applicable conditions of the relative dynamic elastic modulus of air-entraining concrete under the action of the long-term salt immersion are obtained, which can be used to evaluate and precast the durable degree of air-entraining concrete in the salt environment.

Comparison and Selection of the Durability Evaluating Parameters of Concrete in Saline Soil Region

2014 ◽  
Vol 919-921 ◽  
pp. 1751-1754 ◽  
Author(s):  
Li Zhang ◽  
Xiao Ping Su
Keyword(s):  
Elastic Modulus ◽  
Saline Soil ◽  
Degradation Process ◽  
Dynamic Elastic Modulus ◽  
Failure Behavior ◽  
Concrete Durability ◽  
Salt Corrosion ◽  
Concrete Damage ◽  
Main Index ◽  
Durability Of Concrete

The mal-condition of environment directly affects the durability of concrete, and which has become a widespread problem under the complicated environment conditions. Domestic and overseas scholars have carried out many researches on the durability of concreteunder different environmental conditions. The mass and the dynamic elastic modulus loss are focused as two major criteria in the evaluation of concrete damage. The article further gives researches on the durability of concrete in the saline soil environment in the west region of Jilin province. The concrete durability tests are conducted under the actions of salt soaking, salt corrosion and freezing-thawing cycles, and salt corrosion and dry-wet cycles. Comparing the test results in the same coordinate system, it is concluded that the dynamic elastic modulus of concrete can reflect the degradation process of concrete performance more accurately and intuitively, and forecast the failure behavior of concrete under the action of various environmental factors timely and effectively. Therefore it can be used as the main index for no damage detection, while the mass loss can be acted as the auxiliary detection index during the concrete durability tests.

scholarly journals Influence of Crack on Concrete Damage in Salt-Freezing Environment

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Guangyan Liu ◽  
Song Mu ◽  
Jingshun Cai ◽  
Deqing Xie ◽  
Ying Zhou ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Mass Loss ◽  
Crack Width ◽  
Mass Loss Rate ◽  
Development Trend ◽  
Initial Crack ◽  
Dynamic Elastic Modulus ◽  
Damage Development ◽  
Concrete Damage ◽  
Freezing Cycle

The damage development trend of concrete with cracks in salt-freezing environment is systematically studied. The cracks are also tested in intact concrete for comparison, and crack characterization is introduced. The mass loss, the relative dynamic elastic modulus, and the change of crack width are analyzed. Results show that the crack width increases as the salt-freezing cycle progresses. Following the development trend of the cracks, concrete cracks can be divided into three categories: 0–40, 40–100, and 100–150 μm. The mass loss increases significantly, and the change of relative dynamic elastic modulus decreases in concrete with an initial crack compared with the intact concrete. When the crack width is 80 μm, a maximum mass loss rate of 0.19% and a minimum relative dynamic elastic modulus of 75.81% can be obtained. These test results prove that crack and freeze-thaw coupling can influence each other and accelerate the failure of concrete. Overall, this study can serve as a basis for the durability design and life improvement of concrete structures.

scholarly journals Undrained Dynamic Behavior of Reinforced Subgrade under Long-Term Cyclic Loading

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Min Geng ◽  
Debin Wang ◽  
Peiyong Li
Keyword(s):  
Elastic Modulus ◽  
Cyclic Loading ◽  
Dynamic Behavior ◽  
Vibration Frequency ◽  
Dynamic Stress ◽  
Stress Amplitude ◽  
Confining Pressure ◽  
Reinforced Soil ◽  
Dynamic Elastic Modulus

To study the dynamic behavior of reinforced subgrade, a series of undrained cyclic triaxial tests of reinforced soil (the specimen a height of 50 cm and a diameter of 20 cm) were performed in this paper. The specimens were tested by varying confining pressure, vibration frequency, dynamic stress amplitudes, and reinforced layers. Orthogonal experiment is a better way to optimize the process of experiment. Impact on dynamic behavior of the reinforced soil specimens is discussed through orthogonal design of experiments in four factors and three levels. This study has demonstrated that the order of dynamic elastic modulus of reinforced soil is influenced by dynamic stress amplitude, frequency, reinforced layer, and confining pressure within changing in factor level. The dynamic stress amplitude has great influence on the dynamic elastic modulus of reinforced soil. The bearing capacity and dynamic elastic modulus of reinforced subgrade decrease slightly with the increase of dynamic strain. Frequency has an influence on the dynamic elastic modulus. It is shown that the cumulative strain of reinforced soil is related to the vibration frequency. The test results also exemplify the reinforced subgrade restrict lateral displacement of subgrade and reduce settlement of subgrade under long-term cyclic loading.

Study on the Durability of Air Entrained Concrete after Long-Term Soaking in Multi-Salt Solution

2014 ◽  
Vol 716-717 ◽  
pp. 375-378
Author(s):  
Xiao Ping Su ◽  
Ting Ting Wang
Keyword(s):  
Loss Rate ◽  
Salt Crystallization ◽  
Soluble Salts ◽  
Physical Damage ◽  
Growth Trend ◽  
Chemical Erosion ◽  
Salt Corrosion ◽  
Air Entrained Concrete ◽  
Better Than

The concrete structures have been long-term corroded by soluble salts in the salinized soil, which was simulated by the way of concrete being soaked in multiple salts solution, then the failure law and mechanism of concrete was studied in this paper. The results show that salt crystallization happens on the exposed parts of concrete, the quality loss rate of concrete takes on the reduction-growth trend and the relative dynamic elastic modulus takes on the reduction-growth trend, the salt corrosion resistance of air entrained concrete is better than that of non-air-entrained concrete after long-term soaking in multiple salts solution. The failure mechanism of concrete is the result of interaction between the physical damage of salts crystallization and chemical erosion, but the former is much easier to implement than the latter.

Distillation of high concentrated salt solution by vacuum multi effect membrane distillation (VMEMD) of memsys

2015 ◽  
Vol 10 (3) ◽  
pp. 478-485 ◽  
Author(s):  
M. Wenzel ◽  
S. Büttner ◽  
W. Heinzl ◽  
S. Heinzl
Keyword(s):  
Salt Solution ◽  
Salt Water ◽  
Membrane Distillation ◽  
Separation Process ◽  
Recovery Ratio ◽  
Distillation Process ◽  
High Recovery ◽  
Distillate Output ◽  
Hydrophobic Membranes

Vacuum multi effect membrane distillation (VMEMD) is a thermal separation process with microporous hydrophobic membranes that is able to concentrate liquids with high salt concentrations close to saturation. This document describes the technology, test runs with high concentrated salt solution, observed phenomena and experiences gathered from the testing with VMEMD modules by memsys. Salt influences the distillation process in direction to lower distillate output due to boiling point elevation of the salt water. The process proofs reliability in a 365 days long-term testing with feed at conductivities between 130′000 μS/cm and 240′000 μS/cm (approximately 9.5–22wt% salt in solution) and distillate output with less than 10 μS/cm. The testing program delivers experience for the layout of modules with high recovery ratio.

scholarly journals Long-Term Stability of Different Kinds of Gas Nanobubbles in Deionized and Salt Water

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1808
Author(s):  
Yali Zhou ◽  
Zhenyao Han ◽  
Chunlin He ◽  
Qin Feng ◽  
Kaituo Wang ◽  
...  
Keyword(s):  
Aqueous Solution ◽  
Bubble Size ◽  
Ostwald Ripening ◽  
Salt Water ◽  
Dlvo Theory ◽  
Deionized Water ◽  
Hydrodynamic Cavitation ◽  
Term Stability ◽  
Long Term Stability

Nanobubbles have many potential applications depending on their types. The long-term stability of different gas nanobubbles is necessary to be studied considering their applications. In the present study, five kinds of nanobubbles (N2, O2, Ar + 8%H2, air and CO2) in deionized water and a salt aqueous solution were prepared by the hydrodynamic cavitation method. The mean size and zeta potential of the nanobubbles were measured by a light scattering system, while the pH and Eh of the nanobubble suspensions were measured as a function of time. The nanobubble stability was predicted and discussed by the total potential energies between two bubbles by the extended Derjaguin–Landau–Verwey–Overbeek (DLVO) theory. The nanobubbles, except CO2, in deionized water showed a long-term stability for 60 days, while they were not stable in the 1 mM (milli mol/L) salt aqueous solution. During the 60 days, the bubble size gradually increased and decreased in deionized water. This size change was discussed by the Ostwald ripening effect coupled with the bubble interaction evaluated by the extended DLVO theory. On the other hand, CO2 nanobubbles in deionized water were not stable and disappeared after 5 days, while the CO2 nanobubbles in 1 mM of NaCl and CaCl2 aqueous solution became stable for 2 weeks. The floating and disappearing phenomena of nanobubbles were estimated and discussed by calculating the relationship between the terminal velocity of the floating bubble and bubble size.

Studies the Properties of Polyaspartic Polyurea Coated Concrete under Coaction of Salt Fog and Freeze-Thaw

2012 ◽  
Vol 455-456 ◽  
pp. 781-785
Author(s):  
Ping Lu ◽  
Xin Mao Li ◽  
Xue Qiang Ma ◽  
Wei Bo Huang
Keyword(s):  
Elastic Modulus ◽  
Frost Resistance ◽  
Dynamic Elastic Modulus ◽  
Freeze Thaw ◽  
Decrease Rate ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Salt Fog

. This paper mainly studied the properties of PAE polyurea coated concrete under coactions of salt fog and freeze-thaw. After exposed salt fog conditions for 200d, T3, B2, F2 and TM four coated concrete relative dynamic elastic modulus have small changes, but different coated concrete variation amplitude is different. T3 coated concrete after 100 times of freeze-thaw cycle the relative dynamic elastic modulus began to drop, 200 times freeze-thaw cycle ends, relative dynamic elastic modulus variation is the largest, decrease rate is 95%, TM concrete during 200 times freeze-thaw cycle, relative dynamic elastic modulus almost no change, B2 concrete and F2 concrete the extent of change between coating T3 and TM. After 300 times the freeze-thaw cycle coated concrete didn't appear freeze-thaw damage phenomenon. Four kinds of coating concrete relative dynamic elastic modulus variation by large to small order: T3 coated concrete > B2 coated concrete >F2 coated concrete > TM coated concrete, concrete with the same 200d rule. Frost resistance order, by contrast, TM coated concrete > B2 coated concrete > F2 coated concrete > T3 coated concrete.

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