Sulfate attack and role of silica fume in resisting strength loss

2005 ◽  
Vol 27 (1) ◽  
pp. 65-76 ◽  
Author(s):  
S.T. Lee ◽  
H.Y. Moon ◽  
R.N. Swamy
Keyword(s):  
Silica Fume ◽  
Strength Loss ◽  
Sulfate Attack

Strength Loss Method to Evaluate the Sulfate Attack Resistance of the Cement-Porous Silica Fume Mortar

2014 ◽  
Vol 576 ◽  
pp. 133-141
Author(s):  
Shou Qi Zhang ◽  
Shu Xiong Zhang ◽  
Yu Fang Fu ◽  
Dong Min Wang
Keyword(s):  
Silica Fume ◽  
Cement Mortar ◽  
Porous Silica ◽  
Acid Leaching ◽  
Strength Loss ◽  
Sulfate Attack ◽  
Holding Time ◽  
Mineral Admixture ◽  
Material Development ◽  
Asbestos Tailings

The key factors for activity of asbestos tailings acid leaching residue (ATALR) and activated process were researched by the way of orthoplan, so as to make a new type of high-active mineral admixture in cement-based material, named as porous silica fume (PSF). Then with the strength loss indexes designed, the sulfate attack resistance of cement-PSF mortars was evaluated, which was dunked in solution of sodium sulfate during from 6 to 12 months. The results indicated that thermal activated temperature and holding time was the key factor for compressive strength, while holding time and grinding time for flexural strength. The optimal activated process was the thermal activated temperature at800°C needing to hold for 1 hour before grinding for 20minuteswhilethe appropriate amount of PSF was 5%~12% in cement mortar. When 5%~8% PSF contained, the sulfate attack resistance of cement mortar can be improved obviously, and the role was similar to silica fume (SF). PSF activated from ATALR is helpful for resource utilization of asbestos tailings, in order to improve ecological environment in the asbestos mine town and promote cement-based material development.

Mitigating effect of chloride ions on sulfate attack of cement mortars with or without silica fume

2008 ◽  
Vol 35 (11) ◽  
pp. 1210-1220 ◽  
Author(s):  
Seung-Tae Lee ◽  
Dae-Wook Park ◽  
Ki-Yong Ann
Keyword(s):  
Silica Fume ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Chloride Ions ◽  
X Ray Diffraction ◽  
Friedel’S Salt ◽  
Cement Mortars ◽  
Binder Ratio ◽  
Change Of Porosity

This paper presents a detailed experimental study on the sulfate attack of mortar specimens with or without silica fume exposed to sulfate and sulfate–chloride solutions (with the same concentration of SO42– ions) up to 510 d. The overall aim of the study is to investigate the beneficial effect of chloride ions on sulfate attack. In addition, the role of silica fume and water–binder ratio (w/b) in resisting sulfate attack is also reported. To qualitatively assess the performance of mortar specimens exposed to test solutions, visual examination and compressive strength and expansion tests were carried out. X-ray diffraction (XRD) and mercury intrusion porosimetry (MIP) techniques were also used to evaluate the products formed by hydration and chemical reaction and the change of porosity for paste samples. Results indicated that the presence of chloride ions in sulfate environments mitigated the deterioration of ordinary Portland cement mortar specimens, especially with a higher w/b, due to sulfate attack. It seems that the mitigating effect of chloride ions on sulfate attack is attributable to the increased solubility of sulfate products in the chloride-bearing sulfate solution, and the chemical binding of the ions to form Friedel’s salt.

scholarly journals Deterioration and Microstructural Evolution of the Fly Ash Geopolymer Concrete against MgSO4Solution

2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Tao Long ◽  
Qingyuan Wang ◽  
Zhongwei Guan ◽  
Yu Chen ◽  
Xiaoshuang Shi
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Magnesium Sulfate ◽  
Strength Loss ◽  
Sulfate Attack ◽  
Aluminum Silicate ◽  
Geopolymer Concrete ◽  
Portland Cement Concrete ◽  
Sodium Aluminum Silicate ◽  
Magnesium Aluminum Silicate

Fly ash geopolymer concrete (FAGC) and ordinary Portland cement concrete (OPCC) specimens were immersed in 5% MgSO4solution undergoing 32 wetting-drying and heating-cooling cycles. Their compressive behavior was investigated after every 8 cycles. Several microstructure analysis techniques were applied on the samples to identify the materials formed due to magnesium sulfate attack, including XRD, FTIR, SEM, and EDS. Experimental results elucidated that the compressive strength loss ratio in the heating group of FAGC was 12.7%, while that of OPCC was 17.8%, which means that FAGC had better magnesium sulfate resistance than OPCC. The compressive strength loss of OPCC was due to the formation of gypsum under the magnesium sulfate attack exposed to wetting-drying and heating-cooling cycles. The deterioration mechanisms of FAGC against MgSO4solution were discovered to be that sodium aluminum silicate hydrate (N-A-S-H) gels reacted with MgSO4, leading to the creation of low strength magnesium aluminum silicate hydrate (M-A-S-H) gels.

The role of MgO in the thermal behavior of MgO–silica fume pastes

2016 ◽  
Vol 127 (3) ◽  
pp. 1897-1909 ◽  
Author(s):  
Zhaoheng Li ◽  
Qijun Yu ◽  
Xiaowen Chen ◽  
Hao Liu ◽  
Jiyao Zhang ◽  
...  
Keyword(s):  
Thermal Behavior ◽  
Silica Fume

The Experimental Research on the Anti-Corrosion Performance of Concrete with Different Mineral Admixtures under Sulfate and Chloride Environment

2014 ◽  
Vol 638-640 ◽  
pp. 1431-1435
Author(s):  
Wen Xun Qian ◽  
Yan Chi Zhang ◽  
Xun Jie Chen ◽  
You Lin Ouyang
Keyword(s):  
Loss Rate ◽  
Chloride Ion ◽  
Strength Loss ◽  
Sulfate Attack ◽  
Mineral Admixtures ◽  
Corrosion Performance ◽  
Chloride Ion Penetration ◽  
Initial Stage ◽  
Chloride Environment ◽  
Permeability Of Chloride Ion

The performance of resistance to sulfate attack and permeability of chloride ion on concrete with different mineral admixtures (fly ash, slag single or both adding) under sulfate and chloride environment were discussed. The results indicated the performance of resistance to salt attack on concrete with appropriate mineral admixtures was improved. Under chloride environment, the resistance to sulfate attack coefficient of testing mortars descended, and compressive strength loss rate of concrete was raised after dry-wet cycles. Therefore, the performance of resistance to salt attack on concrete was decreased in this environment. Besides, on the initial stage of corrosion, the ability to resist chloride ion penetration of concrete was improved under sulfate environment, while the penetrating of chloride ion was accelerated on the later stage.

scholarly journals An Investigation on Strength Development of Cement with Cenosphere and Silica Fume as Pozzolanic Replacement

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
K. Senthamarai Kannan ◽  
L. Andal ◽  
M. Shanmugasundaram
Keyword(s):  
Silica Fume ◽  
Strength Loss ◽  
Strength Reduction ◽  
Strength Development ◽  
Test Results ◽  
Hydration Products

In the detailed study presented in this paper, an attempt was made to study the strength of cement when cenosphere (CS) and silica fume (SF) were used as replacement. Tests were carried out on mix with cenosphere as replacement for cement which has 12% of constant replacement of silica fume to the mass of cement, and this is made to stabilize the strength which was lost due to addition of cenosphere. From the test results, it was concluded that the strength loss of binder due to replacement of cenosphere can be stabilized by silica fume and still a safe value of strength can be achieved. Furthermore, the strength reduction is due to the consumption of hydration products and cloggy microstructure as observed in this study.

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