scholarly journals Mechanical behavior and durability of mortars with quartzite and Portland cement after sulfate attack

2019 ◽  
Vol 24 (4) ◽  
Author(s):  
Sâmea Valensca Alves Barros ◽  
Gelmires de Araújo Neves ◽  
Romualdo Rodrigues Menezes ◽  
Gerbeson Carlos Batista Dantas ◽  
Patrícia Mendonça Pimentel
Keyword(s):  
Mechanical Behavior ◽  
Sodium Sulfate ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Sodium Sulfate Solution ◽  
Differential Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dimensional Variation ◽  
Complementary Techniques

ABSTRACT The residues of ornamental rocks, especially quartzite, cause great environmental impact. More impulse has been given to research on the recycling of these residues over the last years, particularly for use as aggregates in concrete and mortar. Nevertheless, the studies conducted so far do not mention the behavior of the mortar blended with aggregates coming from residues of ornamental rocks when under chemical attacks in sulfate-rich environment. Thus, in the present study it was sought to add quartzite residues to the mortar, verifying its mechanical behavior and its durability when attacked by sodium sulfate (Na2SO4). The durability of the mortar blended with quartzite residues under sulfate attack was evaluated by the dimensional variation of the test specimens when immersed in sodium sulfate solution, according to the methodology of the NBR 13583 standard. Were used the following complementary techniques: simple compressive strength, X-ray diffraction and thermogravimetric and differential analysis. From the tests, it was verified that the mortars, after attack of sodium sulfate, presented dimensional expansions superior to 0.06%, as well as increased mechanical strength. Therefore, although it was found that the specimens incorporated with quartzite residues were attacked by sulfate, it was observed that it was not able to form sufficient secondary ettringite to mechanically damage the specimens submitted to the sodium sulfate attack.

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.

Deterioration of concrete containing limestone powder exposed to sulfate attack at ambient temperature

2021 ◽  
Vol 11 (5) ◽  
pp. 724-731
Author(s):  
Hemin Liu ◽  
Qian Huang ◽  
Liang Zhao
Keyword(s):  
Ambient Temperature ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Limestone Powder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mineral Phases ◽  
Adverse Influence ◽  
Powder Content ◽  
Scanning Electron

This study investigates the deterioration of concrete containing limestone powder exposed to sulfate solution under ambient temperature (20~25 °C). Microstructure and mineral phases within the attacked concrete were measured by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and X-ray diffraction (XRD). It was found that the addition of limestone powder increased the initial porosity of concrete. Consequently, a larger amount of SO2–4 ions diffused into the concrete containing limestone powder, and their degree of deterioration caused by sulfate attack increased with the increase in limestone powder content. At ambient temperature, gypsum and ettringite were the major attack products, respectively within the surface and nearsurface portions of concrete containing limestone powder, which was consistent with the products of sulfate attack within concrete without limestone powder. Therefore, the type and distribution of the attack products in concrete had not been revised due to the addition of limestone powder. Nevertheless, the adverse influence of limestone powder on the sulfate resistance of concrete, even at ambient temperature, should be considered. Furthermore, effective measures should be implemented to improve the durability of concrete containing limestone powder in this environment.

Accelerate Thaumasite Formation in Cement-Limestone Powder Paste by Internal Adding Method

2011 ◽  
Vol 250-253 ◽  
pp. 22-27 ◽  
Author(s):  
Chang Cheng Li ◽  
Yan Yao ◽  
Ling Wang
Keyword(s):  
Magnesium Sulfate ◽  
Sodium Sulfate ◽  
Calcium Sulfate ◽  
Sulfate Attack ◽  
Limestone Powder ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cement Based Materials ◽  
Internal Sulfate Attack

Cement-limestone powder pastes added with 10% magnesium sulfate, sodium sulfate, and calcium sulfate respectively were stored in water at (5±2) °C to accelerate thaumasite formation. The pastes were inspected visually at intervals. And the formation of thaumasite was identified and confirmed by X-ray diffraction (XRD), infrared spectroscopy (IR), and nuclear magnetic resonance spectroscopy (NMR). The results show that internal adding sulfate in cement-limestone powder paste is an efficient way to accelerate thaumasite formation, and the accelerated effect is magnesium sulfate> sodium sulfate> calcium sulfate. Cement-limestone paste containing 10% magnesium sulfate totally turns into grey-white mushy materials after 6 months immersion, and products are mainly thaumasite and gypsum. In addition, the amount of thaumasite increases along with time of internal sulfate attack in 15 months. XRD, IR, and NMR are powerful and reliable tools for identification of thaumasite in cement-based materials.

Long-term sulfate attack on recycled aggregate concrete immersed in sodium sulfate solution for 10 years

2020 ◽  
Vol 70 (337) ◽  
pp. 212
Author(s):  
L. R. Santillán ◽  
F. Locati ◽  
Y. A. Villagrán-Zaccardi ◽  
C. J. Zega
Keyword(s):  
Sodium Sulfate ◽  
Fluorescent Microscopy ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Recycled Concrete ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Concrete Aggregate ◽  
Sodium Sulfate Solution ◽  
Microscopy Image

The effect of recycled concrete aggregate (RCA) on concrete performance against external sulfate attack (ESA) is not yet fully known. In this paper, recycled aggregate concretes (RAC) with 0, 50, 75 and 100% of RCA contents were evaluated after 10 years of exposure immersed in 50g/l sodium sulfate solution. Sulfate ingress profiles were obtained by wet chemical analyses and FRX. Also, the mineralogy of the ingress profile was evaluated by thermogravimetric analyses. Finally, microcracking development in samples was evaluated by optical fluorescent microscopy image analysis. Although RAC showed a slight increase in sulfate ingress, due to its higher porosity (about 30% higher SO3 content near the surface for 50% or higher replacement ratio than control concrete), a dense new matrix still allows a good performance of RAC to external sulfate attack with even 100% RCA content.

Influence of Fly Ash on Thaumasite Form of Sulfate Attack in Cement-Based Materials

2013 ◽  
Vol 377 ◽  
pp. 74-79
Author(s):  
Chang Cheng Li ◽  
Fu Jie Jia ◽  
Xu Nan Wu
Keyword(s):  
Fly Ash ◽  
Activity Index ◽  
Early Stage ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Minor Role ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cement Based Materials ◽  
A Minor

A low temperature sulfate attack research was carried out to investigate the effects of fly ash on thaumasite form of sulfate attack (TSA) in cement-based materials. Cement-limestone-fly ash samples were immerged in 5% magnesium sulfate solution at (5±2) oC. The appearance of samples was observed, and strength was also tested. Besides, the corrosion products were analyzed by infrared spectrum (IR) and X-ray diffraction (XRD) methods. Cement was equally replaced by fly ash with 20%, 30%, and 50% proportions. The results show that: Effects of fly ash on TSA were closely related to the composition, content and fineness of fly ash. Fly ash with an activity index larger than 80% could improve the resistance to TSA in cement-based materials when the replacement reached 50% while fly ash only played a minor role in early stage with 20%-30% content.

Rapid Quantitative Identification of Thaumasite

2013 ◽  
Vol 743-744 ◽  
pp. 186-192 ◽  
Author(s):  
Chang Cheng Li ◽  
Yan Yao ◽  
Ling Wang
Keyword(s):  
Magnesium Sulfate ◽  
Rietveld Refinement ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Limestone Powder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Identification Method ◽  
Quantitative Identification ◽  
Ir Analysis

To establish a quantitative identification method of thaumasite, internal doping method was used to accelerate thaumasite form of sulfate attack (TSA). A cement-limestone powder paste doped 10% of magnesium sulfate was immersed in water at (5±2) °C, while the blank was in 10% magnesium sulfate solution (by weight). Paste corrosion products were analyzed by infrared spectrum (IR), thermal analysis, nuclear magnetic resonance (NMR), and X-ray diffraction (XRD)/Rietveld refinement methods. The results show that the thaumasite formation was successfully accelerated by internal doping method. A lot of thaumasite formed after 6-15 months low temperature sulfate attack with gray mud-like material. IR analysis is able to be used to analysis thaumasite qualitatively, and Rietveld refinement was suitable to quantitative analysis of thaumasite. A rapid quantitative identification method of thaumasite including visual inspection, IR spectrum and XRD/Rietveld refinement was also established which will improve the accuracy and rapidness of TSAs research.

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.

The Effect of Fly Ash on TSA of Cementitous Material: Based on Three Years Results

2013 ◽  
Vol 539 ◽  
pp. 139-144
Author(s):  
Ben Wan Liu ◽  
Chang Hui Yang ◽  
Xiao Bin Xiang ◽  
Lin Wen Yu ◽  
Jing Zhang
Keyword(s):  
Fly Ash ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Hardened Cement ◽  
Hydration Reaction ◽  
X Ray Diffraction ◽  
Hardened Cement Paste ◽  
X Ray ◽  
Ft Ir ◽  
Secondary Hydration

The thaumasite form of sulfate attack of cementitous material (TSA) is a new kind of sulfate attack and it is more harmful than traditional sulfate attack. By means of Fourier transform infrared (FT-IR) and X-ray diffraction (XRD), the effect of dosage and fineness of fly ash on TSA of cementitous material were investigated in this paper. The specimens had been immersed in magnesium sulfate solution of 5% mass concentration at 5±2° C for three years. The results showed that fly ash could not restrain the formation of thaumasite but it delayed the occurrence of TSA in cementitous material when 30% fly ash takes place of cement. Fly ash could enhance the resistance of cementitous material to TSA through secondary hydration reaction to optimizing the pore structure of hardened cement paste and lowering the C/S of C-S-H gel.

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