ETTRINGITE FORMATION IN LOW C 3 A PORTLAND CEMENT EXPOSED TO SODIUM SULFATE SOLUTION

1997 ◽  
Vol 27 (7) ◽  
pp. 1061-1071 ◽  
Author(s):  
M.A. González ◽  
E.F. Irassar
Keyword(s):  
Portland Cement ◽  
Sodium Sulfate ◽  
Sulfate Solution ◽  
Sodium Sulfate Solution ◽  
Ettringite Formation

scholarly journals The Resistance of New Kind of High-Strength Cement after 5 Years Exposure to Sulfate Solution

2020 ◽  
Author(s):  
Michal Bačuvčík ◽  
Pavel Martauz ◽  
Ivan Janotka ◽  
Branislav Cvopa
Keyword(s):  
Portland Cement ◽  
Pore Structure ◽  
Sodium Sulfate ◽  
High Strength ◽  
Sulfate Solution ◽  
Mechanical Tests ◽  
Sodium Sulfate Solution ◽  
Sulfate Resistance ◽  
Reference Medium

This article deals with the determination of technically important properties, the recognition of microstructure and pore structure, and the mortar resistance of a new cement kind NONRIVAL CEM I 52.5 N containing 7.94% wt. of C3A to 5% sodium sulfate solution. Both reference types of cement were industrially manufactured: 1) ordinary Portland cement CEM I 42.5 R and 2) Portland cement CEM I 42.5 R – SR 0, declared as sulfate resistant because of C3A = 0%. The research was carried out at standardized mortars. The used sodium sulfate solution, which contained 33802.8 mg of aggressive SO4 2− per liter, exceeded approximately 5 to 10 times the concentration of the third degree of aggressiveness of the XA chemical environment according to STN EN 206 + A1. The reference medium was drinking water. The 5-year results of non-destructive and destructive physical-mechanical tests as well as the formed microstructure and pore structure in both liquid media were evaluated. The cause of the NONRIVAL CEM I 52.5 N sulfate resistance was explained, despite the manufacturer’s declared C3A content of up to 8% by weight. Sulfate resistance of NONRIVAL CEM I 52.5 N is found comparable to that of sulfate resistant CEM I 42.5 R – SR 0.

scholarly journals Durability of Mortars with Fly Ash Subject to Freezing and Thawing Cycles and Sulfate Attack

Materials ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 220
Author(s):  
Monika Jaworska-Wędzińska ◽  
Iga Jasińska
Keyword(s):  
Fly Ash ◽  
Portland Cement ◽  
Sodium Sulfate ◽  
Sulfate Solution ◽  
Physical Factors ◽  
Sodium Sulfate Solution ◽  
Freezing And Thawing ◽  
High Calcium ◽  
High Calcium Fly Ash ◽  
Freezing And Thawing Cycles

Destruction of cement composites occurs due to the alternate or simultaneous effects of aggressive media, resulting in the destruction of concrete under the influence of chemical and physical factors. This article presents the results of changes in the measurement of linear strains of samples and changes in the microstructure of cement after 30 freezing and thawing cycles and immersed in 5% sodium sulfate solution. The compressive strengths ratios were carried out at the moment when the samples were moved to the sulfate solution after 30 cycles and at the end of the study when the samples showed visual signs of damage caused by the effect of 5% Na2SO4. The composition of the mixtures was selected based on the Gibbs triangle covering the area up to 40% replacement of Portland cement with low and high-calcium fly ashes or their mixture. Air-entrained and non-air entrained mortars were made of OPC, in which 20%, 26.6%, and 40% of Portland cement were replaced with low and/or high-calcium fly ash. Initial, freezing and thawing cycles accelerated the destruction of non- air-entrained cement mortars immersed in 5% sodium sulfate solution. The sulfate resistance, after the preceding frost damage, decreased along with the increase in the amount of replaced fly ash in the binder. Air-entrained mortars in which 20% of cement was replaced with high-calcium fly ash showed the best resistance to the action of sodium sulfate after 30 freezing and thawing cycles.

X-Ray Microtomography of an Astm C109 Mortar Exposed to Sulfate Attack

1994 ◽  
Vol 370 ◽  
Author(s):  
D.P. Bentz ◽  
Nicos. S. Martys ◽  
P. Stutzman ◽  
M. S. Levenson ◽  
E.J. Garboczi ◽  
...  
Keyword(s):  
Cement Paste ◽  
Sodium Sulfate ◽  
Three Dimensional ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Sodium Sulfate Solution ◽  
Mortar Sample ◽  
Air Voids ◽  
X Ray ◽  
Dimensional Image

AbstractX-ray microtomography can be used to generate three-dimensional 5123 images of random materials at a resolution of a few micrometers per voxel. This technique has been used to obtain an image of an ASTM C109 mortar sample that had been exposed to a sodium sulfate solution. The three-dimensional image clearly shows sand grains, cement paste, air voids, cracks, and needle-like crystals growing in the air voids. Volume fractions of sand and cement paste determined from the image agree well with the known quantities. Implications for the study of microstructure and proposed uses of X-ray microtomography on cement-based composites are discussed.

Durability of cement mortars incorporating limestone filler exposed to sodium sulfate solution

2014 ◽  
Vol 19 (5) ◽  
pp. 1347-1358 ◽  
Author(s):  
Jaesuk Ryou ◽  
Seungtae Lee ◽  
Daewook Park ◽  
Seongsoo Kim ◽  
Hoseop Jung
Keyword(s):  
Sodium Sulfate ◽  
Sulfate Solution ◽  
Sodium Sulfate Solution ◽  
Limestone Filler ◽  
Cement Mortars

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.

Effect of Stabilizer and Molding Technics in Chemical Engineering on the Stabilization of Sulfate Rich Soil

2012 ◽  
Vol 577 ◽  
pp. 65-68
Author(s):  
Xiao Xuan Deng ◽  
Lei Dai ◽  
Xin Huang
Keyword(s):  
Production Rate ◽  
Sodium Sulfate ◽  
Calcium Silicate ◽  
Chemical Engineering ◽  
Sulfate Solution ◽  
Cementitious Materials ◽  
Sodium Sulfate Solution ◽  
Calcium Silicate Hydrates

In chemical engineering field, ettringite (AFt) formation effect the stabilization of sulfate rich soil mixed with cementitious materials. The different stabilizer compositions and twice molding technics may avoid and repair the destruction caused by AFt with decreasing the production rate of calcium silicate hydrates(C-S-H) and eliminating the void in stabilized soils. The results show that the strength of stabilized 5% sodium sulfate bearing soils, under above methods, are not less than that of the control ones, and the specimens keep steady after soaking in 5% sodium sulfate solution for 12 weeks.

scholarly journals Experimental Study on the Durability of Fly Ash-Based Filling Paste in Environments with Different Concentrations of Sulfates

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Boqiang Cui ◽  
Yin Liu ◽  
Hao Guo ◽  
Zhanxin Liu ◽  
Yao Lu
Keyword(s):  
Fly Ash ◽  
Sodium Sulfate ◽  
Sulfate Solution ◽  
Mechanical Analysis ◽  
Test Block ◽  
Sodium Sulfate Solution ◽  
Stress Strain ◽  
Hydrated Calcium Silicate ◽  
Soaking Time ◽  
Hydrated Products

In order to study the effects of different concentrations of sulfate on the strength of fly ash-based coal mine filling paste, using variable control, mechanical analysis, and other means, the changes in the uniaxial compressive strengths of filling paste blocks soaked in different concentrations of sodium sulfate solution for different durations are studied, and their stress-strain curves are discussed. The hydrated products of each block are analyzed at different stages by XRD, and the results indicate that different concentrations of sodium sulfate solution have different effects on the strength of the filling paste after soaking for different durations. A sodium sulfate solution with a concentration of 5% had an activator effect on the fly ash-based filling paste and enhanced the strength of the filling paste. A sodium sulfate solution with a concentration of 10% and 15% increased the early strength of the paste test block faster, but after 60 d, the strength decreased. The stress-strain curves for these blocks show that the elastic moduli of the filling paste test blocks change irregularly, and it was found that with the increase in soaking time, the blocks soaked in the 10% and 15% sodium sulfate solutions developed fissures in the later stage that adversely affected the strength of the filling paste. The XRD results show that the filling paste test block hydration products are hydrated calcium silicate (C-S-H) based and that ettringite (AFt), beneficial to strength of the filling paste in proper quantities, appeared in the main product of the filling paste test blocks that were soaked in the sodium sulfate solution. With the increase in the concentration of the sodium sulfate solution, the AFt is generated in larger quantities, and gypsum crystals begin to appear, which is not conducive to the filling paste block strength.

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