scholarly journals Effects of Sodium Sulfate Attack on Concrete Incorporated with Drying-Wetting Cycles

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Fang Liu ◽  
Zhanping You ◽  
Rui Xiong ◽  
Xu Yang
Keyword(s):  
Fly Ash ◽  
Mass Loss ◽  
Sodium Sulfate ◽  
Sulfate Attack ◽  
Distribution Model ◽  
Impact Factors ◽  
Curing Time ◽  
Sulfate Ion ◽  
Damage Degree ◽  
The Impact

It has been widely observed that sulfate attack can damage the durability of concrete. This research investigated the mass loss and damage degree of concrete under sodium sulfate attack incorporated with drying-wetting cycles. The impact factors, including water-binder ratio, solution concentration of sodium sulfate, fly ash content, curing time, and drying-wetting cycle system, were observed to influence the sodium sulfate attack by the mass loss rate and damage degree at regular time intervals. Also, the hydrates of sulfate-attacked samples were analyzed using X-ray diffraction. Results indicated that a high water-binder and high-concentration sodium sulfate solution could accelerate the transportation of sulfate ion inside the concrete and the deterioration degree of concrete. Appropriate fly ash and longer curing time can effectively improve the internal pore structure of concrete to reduce the sulfate corrosion damage. The sulfate ion erosion and deterioration degree of the concrete are synchronously intensified along with the increase of the baking-immersing time ratio. The trend of the predicted life for concrete is basically consistent with the damage evolution result, indicating the feasibility of the Weibull distribution model to predict the service life of concrete under sodium sulfate attack incorporated with drying-wetting cycles.

scholarly journals Deterioration Regularity of Sodium Sulfate Solution Attack on Cemented Coal Gangue-Fly Ash Backfill under Drying-Wetting Cycles

2020 ◽  
Vol 2020 ◽  
pp. 1-13
Author(s):  
Shaojie Chen ◽  
Zhen Zhang ◽  
Dawei Yin ◽  
Junbiao Ma
Keyword(s):  
Fly Ash ◽  
Sodium Sulfate ◽  
Sulfate Solution ◽  
Coal Gangue ◽  
Salt Crystallization ◽  
Sodium Sulfate Solution ◽  
Sulfate Ion ◽  
Sulfate Ions ◽  
Ion Contents ◽  
The Masses

To research the properties of cemented coal gangue-fly ash backfill (CGFB) exposed to different concentrations of sodium sulfate solutions under drying-wetting cycles, the mass changes, uniaxial compressive strengths, sulfate ion contents at different depths, and microstructures of CGFB samples were measured in this study. The results show that the CGFB samples were damaged by salt crystallization in the dry state and attacked by the expansive products in the wet state. The sulfate ion contents in CGFB samples increased with the sulfate concentrations and drying-wetting cycles and decreased from the surface to the inside of the samples. The damage process of CGFB samples evolved from the surface to the inside. In the early stage of corrosion, sulfate ions adsorbed to the surface of CGFB samples and consumed nonhydrated particles to form acicular ettringite and other products that filled the material pores. For this stage, the driving force of sulfate ions to enter into the CGFB samples was the highest for the samples immersed in 15% sodium sulfate solution, and the masses and strengths increased the fastest. As the drying-wetting cycles continued, the nonhydrated particles inside the samples were nearly completely hydrated, and the samples were constantly damaged by salt crystallization and dissolution. The corrosion ions entered into the samples and consumed portlandite to produce a large amount of prismatic ettringite and aggravated the internal corrosion of CGFB samples. At the fifteenth drying-wetting cycle, the higher the salt concentration of the immersion solution was, the faster the masses and the strengths of CGFB samples decreased. Moreover, the surface spalling and failure of CGFB samples were more severe.

scholarly journals Cement-fly ash mortars durability, with fly ash from fluidized bed boilers and conventional combustion, exposed to aggressive environment influence

2018 ◽  
Vol 174 ◽  
pp. 02006 ◽  
Author(s):  
Elżbieta Janowska-Renkas ◽  
Jolanta Kowalska ◽  
Grzegorz Janus ◽  
Agnieszka Kaliciak
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Mass Loss ◽  
Fluidized Bed ◽  
Total Porosity ◽  
Environment Impact ◽  
Fly Ashes ◽  
Aggressive Environment ◽  
Cement Mortars ◽  
The Impact

The study shows results of research on the aggressive environment impact (1, 3 and 5% HCl solution) on durability of cement mortars with fraction from 30 to 45% by mass of fly ashes from the fluidized bed combustion (FBC fly ash) and conventional fly ashes used separately and in the form of a mixture. The impact of aggressive environments on durability of cement and ash mortars was tested for aperiod of 365 days, by testing the compressive strength, linear changes, mass loss and porosity. It was demonstrated that mortars with the content of FBC fly ashes, after 365 days of tests showed the higher resistance to aggressive environment impact. It is confirmed by e.g. their higher compressive strength, and thus the reduced total porosity. Reduction of total porosity content (<50 nm) was accompanied by the increased compressive strength, which in the aqueous environment was in favour of cement mortars, and in the aggressive environment in favour of cement and ash mortars. It was demonstrated that the content of pores < 200 nm was lower for mortars with FBC fly ashes and mixtures of ashes regardless of environment the mortars were stored in. A beneficial impact of FBC fly ashes was found on physical properties of mortars, i.e. reduction of the shrinkage, lower mass loss and reduced destruction of mortars in the acid corrosion environment. That effect was especially beneficial for the mortar with higher (45% by mass) content of FBC fly ashes, regardless of aggressive character of the environment.

scholarly journals Damage and Degradation of Concrete under Coupling Action of Freeze-Thaw Cycle and Sulfate Attack

2020 ◽  
Vol 2020 ◽  
pp. 1-17 ◽  
Author(s):  
Wei Tian ◽  
Fangfang Gao
Keyword(s):  
Fly Ash ◽  
Sodium Sulfate ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Sodium Sulfate Solution ◽  
Failure Characteristics ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Freeze Thaw Cycle ◽  
Two Stages

In this study, the mechanical behaviors, failure characteristics, and microstructure of concrete containing fly ash (FA) against combined freeze-thaw cycles and sulfate attack were studied compared with normal concrete, and the formation rates of corrosion products during coupling cycles were investigated. Results showed that, during the coupling action of freeze-thaw cycles and sodium sulfate solution, concrete containing 10% fly ash exposed in 5% sodium sulfate solution exhibited better freeze-thaw resistance. Meanwhile, the variation of compressive strength of concrete during the coupling cycles could be divided into two stages, including the strength enhancement stage and the strength reduction stage. Moreover, the proportion of micropores and capillary pores decreased obviously during combined freeze-thaw cycles and sulfate attack, and excessive concentration of sodium sulfate solution led to more macropores after high-frequency freeze-thaw cycles.

Effect of Fly Ash on Resistance to Sulfate Attack of Cement-Based Materials

2013 ◽  
Vol 539 ◽  
pp. 124-129 ◽  
Author(s):  
Kai Wei Liu ◽  
Min Deng ◽  
Li Wu Mo
Keyword(s):  
Fly Ash ◽  
Pore Structure ◽  
Sodium Sulfate ◽  
Sulfate Solution ◽  
Length Change ◽  
Sulfate Attack ◽  
Sodium Sulfate Solution ◽  
Reaction Products ◽  
Visual Appearance ◽  
Cement Based Materials

The resistance to sulfate attack of mortars containing 0%, 20%, and 40% of fly ash cured in 5 wt. % sodium sulfate solution at 20°C was investigated in this paper. Visual appearance, cracking analysis, velocity of ultrasonic wave and length change were applied to evaluate the sulfate resistance of mortars. The phases and microstructure of the reaction products due to sulfate attack were examined by XRD and SEM, and the pore structure of the mortars was analyzed by MIP. The effects of fly ash on the sulfate attack of mortars were analyzed. Results indicated that the addition of fly ash improved the resistance of sulfate attack significantly, this probably contributed to the pozzonlanic reaction of fly ash.

Sulfate-Ion Diffusion Regularity and Reaction Mechanism of Sodium Sulfate Attack on Carbonized Concrete

2008 ◽  
Vol 400-402 ◽  
pp. 211-214
Author(s):  
Xiao Ke Li ◽  
Shun Bo Zhao ◽  
Chang Cheng Shi
Keyword(s):  
Reaction Mechanism ◽  
Sodium Sulfate ◽  
Concrete Specimen ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Test Results ◽  
Ion Diffusion ◽  
Sulfate Ion ◽  
Titration Method ◽  
Sulfate Solutions

The experiment has been carried out to study the sodium sulfate attack on carbonized concrete. The concrete specimens with strength grade of C50 were first carbonized for 28d in the carbonation box after standard curing, and then immersed into the sodium sulfate solutions of three different concentrations. When the immersed time were up to 30d, 90d, 180d, 270d and 360d, the sulfate-ion concentrations of every layer from the surface to the inside of concrete specimen were measured by the chemical titration method. Based on the test results, the sulfate-ion diffusion regularity and the reaction mechanism of carbonized concrete are analyzed. It can be concluded that the sulfate-ion diffusion regularity and the reaction mechanism of carbonized concrete is completely different from that of un-carbonized concrete, the diffusion of sulfate-ion occupies advantage in the pore water of carbonized concrete, which increases the depth of concrete specimen attacked by sulfate solution.

Properties of MSFAC Long-Term Exposure to Sodium Sulfate Solution

2013 ◽  
Vol 438-439 ◽  
pp. 25-29
Author(s):  
Li Yun Pan ◽  
Jian Dong Liu ◽  
Lun Li ◽  
Xiao Ke Li
Keyword(s):  
Fly Ash ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Ion Concentration ◽  
Capillary Absorption ◽  
Sulfate Ion ◽  
Ion Content ◽  
Powder Samples ◽  
Ion Contents ◽  
Different Depths

Experiments were conducted to study sulfate attack on concrete made machine-made sand and fly ash (MSFAC). The cubes with dimensions of 100 mm were cast and immersed in sodium solution with sulfate-ion concentration of 50000mg/L and tested after exposed for 30, 90, 180, 270, 360 and 540 days. The powder samples were made by steps of drilling, cutting and grinding. The sulfate-ion contents of concrete at different depths were measured by the chemical titration method. The results show that the sulfate-ion content of concrete decreased with depth, the sulfate-ion entered concrete by diffusion, permeation and capillary absorption. The sulfate-ion content of concrete decreased with the increasing replacement of cement by fly ash, and also decreased with the increase of exposure time when 30% of cement is replaced by fly ash. There are some advantages of using fly ash for concrete with machine-made sand to resist sulfate attack.

The Impact of Anglicizing Former German-Language Psychology Journals on Authorship and Citation Frequencies

2012 ◽  
Vol 17 (3) ◽  
pp. 190-198 ◽  
Author(s):  
Günter Krampen ◽  
Thomas Huckert ◽  
Gabriel Schui
Keyword(s):  
Side Effects ◽  
English Language ◽  
General Trend ◽  
Native Language ◽  
Impact Factors ◽  
German Language ◽  
Journal Articles ◽  
Number Of Citations ◽  
The Impact ◽  
Number Of Authors

Exemplary for other than English-language psychology journals, the impact of recent Anglicization of five former German-language psychology journals on (1) authorship (nationality, i.e., native language, and number of authors, i.e., single or multiple authorships), (2) formal characteristics of the journal (number of articles per volume and length of articles), and (3) number of citations of the articles in other journal articles, the language of the citing publications, and the impact factors (IF) is analyzed. Scientometric data on these variables are gathered for all articles published in the four years before anglicizing and in the four years after anglicizing the same journal. Results reveal rather quick changes: Citations per year since original articles’ publication increase significantly, and the IF of the journals go up markedly. Frequencies of citing in German-language journals decrease, citing in English-language journals increase significantly after the Anglicization of former German-language psychology journals, and there is a general trend of increasing citations in other languages as well. Side effects of anglicizing former German-language psychology journals include the publication of shorter papers, their availability to a more international authorship, and a slight, but significant increase in multiple authorships.

Effect of Curing Time on the Performance of Fly Ash Geopolymer-Stabilized RAP Bases

2021 ◽  
Vol 33 (3) ◽  
pp. 04021001
Author(s):  
Maheshbabu Jallu ◽  
Sireesh Saride ◽  
Arul Arulrajah ◽  
Subrahmanyam Challapalli ◽  
Robert Evans
Keyword(s):  
Fly Ash ◽  
Curing Time

scholarly journals Windblown Sand-Induced Degradation of Glass Panels in Curtain Walls

Materials ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 607
Author(s):  
Yuxi Zhao ◽  
Rongcheng Liu ◽  
Fan Yan ◽  
Dawei Zhang ◽  
Junjin Liu
Keyword(s):  
Visible Light ◽  
Mass Loss ◽  
Effective Area ◽  
Area Ratio ◽  
Light Transmittance ◽  
Relative Mass ◽  
Impact Time ◽  
Windblown Sand ◽  
Glass Panels ◽  
The Impact

The windblown sand-induced degradation of glass panels influences the serviceability and safety of these panels. In this study, the degradation of glass panels subject to windblown sand with different impact velocities and impact angles was studied based on a sandblasting test simulating a sandstorm. After the glass panels were degraded by windblown sand, the surface morphology of the damaged glass panels was observed using scanning electron microscopy, and three damage modes were found: a cutting mode, smash mode, and plastic deformation mode. The mass loss, visible light transmittance, and effective area ratio values of the glass samples were then measured to evaluate the effects of the windblown sand on the panels. The results indicate that, at high abrasive feed rates, the relative mass loss of the glass samples decreases initially and then remains steady with increases in impact time, whereas it increases first and then decreases with an increase in impact angle such as that for ductile materials. Both visible light transmittance and effective area ratio decrease with increases in the impact time and velocities. There exists a positive linear relationship between the visible light transmittance and effective area ratio.

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