The role of temperature in the thaumasite formation under the immersion of magnesium sulfate solution

2021 ◽  
pp. 1-28
Author(s):  
Surong Luo ◽  
Zhen Wang ◽  
Qingnan Gong ◽  
Dehui Wang
Keyword(s):  
Magnesium Sulfate ◽  
Cement Mortar ◽  
Energy Dispersive Spectrometer ◽  
Sulfate Solution ◽  
Corrosion Products ◽  
Limestone Powder ◽  
Direct Reaction ◽  
X Ray Diffraction ◽  
Magnesium Sulfate Solution

To clarify the role of temperature in the thaumasite formation of cement mortar under magnesium sulfate solution at two different temperature, the corrosion products and microstructure of cement-based materials with different amounts and particle sizes of limestone powder (LP) were quantitatively analyzed by Fourier Transform Infra-Red (FTIR), thermogravimetric analysis (TGA), X-ray Diffraction (XRD), Scanning Electronic Microscopy (SEM) and Energy Dispersive Spectrometer (EDS). At 5oC, the main corrosion product of cement mortar was gypsum and thaumasite. At 20°C, the main corrosion products of cement mortar were gypsum and ettringite. When the temperature increased from 5°C to 20°C, the contents of ettringite, thaumasite and gypsum changed from 0.3%, 12.3% and 64.6% to 4.6%, 0% and 57.0%, respectively. The formation of thaumasite was the combination of direct reaction with ettringite transformation. The incorporation of LP accelerated the corrosion of mortars, and the change coefficient of compressive strength of mortars decreased from 100% to 47.3% when its content increased from 0% to 30%. Low temperature and incorporation of finer limestone powder enhanced the corrosion of magnesium sulfate solution.

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.

Preparation and Performance of Sulfate Resistance Cement-Based Material

2008 ◽  
Vol 400-402 ◽  
pp. 195-201
Author(s):  
Feng Chen Zhang ◽  
Bao Guo Ma ◽  
Geng Yin ◽  
Yuan Yuan Wu ◽  
Yan Chao Zhu
Keyword(s):  
Magnesium Sulfate ◽  
Energy Dispersive Spectrometer ◽  
Sulfate Solution ◽  
Sulfate Attack ◽  
Surface Erosion ◽  
Initial Surface ◽  
Control Specimen ◽  
X Ray ◽  
Sulfate Resistance ◽  
Magnesium Sulfate Solution

To discuss prevention of sulfate attack, especially thaumasite form of sulfate attack (TSA), sulfate resistance cement based material (SRM) were designed and prepared, and properties of which were investigated systematically. Micro-analytical techniques were introduced to identify erosion substances especially thaumasite, namely Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with X-ray energy dispersive spectrometer(EDS). Results show that SRM have better sulfate resistance, as well as TSA resistance, when exposed to aggressive environment with 33800 ppm mass concentration of SO42- in magnesium sulfate solution at 5°C±2°C. When immersed in magnesium sulfate solution for 40 weeks, compressive strength and tensile strength of SRM are still higher than their initial, and those of control specimen are lower by 33.7%, 36.5% compared to its initial. Surface erosion substances of SRM named S1 are ettringite and gypsum, while those of control specimen are ettringite, gypsum, thaumasite and brucite.

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.

The transformation of corrosion products on 0Cu2Cr carbon steel in the marine

2021 ◽  
Vol 68 (5) ◽  
pp. 457-463
Author(s):  
Hongyu Liu ◽  
Yingxue Teng ◽  
Jing Guo ◽  
Qinghe Xiao ◽  
Miao Wang ◽  
...  
Keyword(s):  
Carbon Steel ◽  
Energy Dispersive Spectrometer ◽  
Low Carbon Steel ◽  
Transformation Process ◽  
Corrosion Products ◽  
Low Carbon ◽  
X Ray Diffraction ◽  
Transformation Mechanism ◽  
Content Type ◽  
Marine Engineering

Purpose This paper aims to explore the transformation process and transformation mechanism of carbon steel under the marine environment. Design/methodology/approach In this paper, the transformation and rust layers corrosion products on 0Cu2Cr carbon steel with different cycles coupon test was investigated and deeply explored by scanning electron microscope, energy dispersive spectrometer, X-ray diffraction. Findings The results showed that the thickness of rust layers grew from 71.83 µm to 533.7 µm with increasing duration of corrosion. The initial corrosion product was γ-FeOOH, then part of the γ-FeOOH continued growing, and under the capillary action, the other part of the γ-FeOOH transformed to α-FeOOH. Originality/value To the best of the authors’ knowledge, this paper puts forward for the first time a new viewpoint of the development of corrosion products of low-carbon steel in two ways. This discovery provides a new idea for the future development of steel for marine engineering.

scholarly journals Importance of Cation Species during Sulfate Resistance Tests for Alkali-Activated FA/GGBFS Blended Mortars

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3547
Author(s):  
Youngkeun Cho ◽  
Joo Hyung Kim ◽  
Sanghwa Jung ◽  
Yoonseok Chung ◽  
Yeonung Jeong
Keyword(s):  
Compressive Strength ◽  
Magnesium Sulfate ◽  
Sulfate Solution ◽  
Magnesium Ions ◽  
Sulfate Resistance ◽  
Granulated Blast Furnace Slag ◽  
Significant Difference ◽  
Furnace Slag ◽  
Alkali Activated ◽  
Magnesium Sulfate Solution

In this study, the changes in mass, compressive strength, and length of blended mortars were analyzed to investigate their sulfate resistance according to the ground granulated blast furnace slag (GGBFS) blending ratio and type of sulfate solution applied. All alkali-activated mortars showed an excellent sulfate resistance when immersed in a sodium sulfate (Na2SO4) solution. However, when immersed in a magnesium sulfate (MgSO4) solution, different sulfate resistance results were obtained depending on the presence of GGBFS. The alkali-activated GGBFS blended mortars showed a tendency to increase in mass and length and decrease in compressive strength when immersed in a magnesium sulfate solution, whereas the alkali-activated FA mortars did not show any significant difference depending on the types of sulfate solution applied. The deterioration of alkali-activated GGBFS blended mortars in the immersion of a magnesium sulfate solution was confirmed through the decomposition of C–S–H, which is the reaction product from magnesium ions, and the formation of gypsum (CaSO4·2H2O) and brucite (Mg(OH)2).

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.

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