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.

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.

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.

scholarly journals Evaluation of external sulfate attack (Na2SO4 and MgSO4): Portland cement mortars containing fillers

2020 ◽  
Vol 13 (3) ◽  
pp. 644-655 ◽  
Author(s):  
D. J. DE SOUZA ◽  
M. H. F. MEDEIROS ◽  
J. HOPPE FILHO
Keyword(s):  
Portland Cement ◽  
Linear Expansion ◽  
Sulfate Attack ◽  
Hardened Cement ◽  
X Ray Diffraction ◽  
Limestone Filler ◽  
Sulfate Ions ◽  
X Ray ◽  
Cement Mortars ◽  
Physical And Chemical

Abstract Sulfate attack is a term used to describe a series of chemical reactions between sulfate ions and hydrated compounds of the hardened cement paste. The present study aims to evaluate the physical (linear expansion, flexural and compressive strength) and mineralogical properties (X-ray diffraction) of three different mortar compositions (Portland Cement CPV-ARI with limestone filler and, with a quartz filler, in both cases with 10% replacement of the cement by weight) against sodium and magnesium sulfate attack (concentration of SO4 2- equal to 0.7 molar). The data collected indicate that the replacing the cement by the two fillers generate different results, the quartz filler presented a mitigating behaviour towards the sulfate, and the limestone filler was harmful to Portland cement mortars, in both physical and chemical characteristics.

scholarly journals Modifying admixtures to cement compositions produced from local raw materials

2018 ◽  
Vol 143 ◽  
pp. 02006
Author(s):  
Daria Vasileva ◽  
Egor Protodiakonov ◽  
Anastasia Egorova ◽  
Svetlana Antsupova
Keyword(s):  
Cement Paste ◽  
Raw Materials ◽  
Mineralogical Composition ◽  
Raw Material ◽  
Free Calcium ◽  
Hardened Cement ◽  
X Ray Diffraction ◽  
Hardened Cement Paste ◽  
X Ray ◽  
Insoluble Compounds

Durability of hardened cement paste depends on chemical and mineralogical composition of Portland cement. The main factor for hardened cement paste is higher content of calcium aluminate and free calcium hydroxide, binding of which into water-insoluble compounds causes increase in resistance to water, frost and corrosion. The purpose of this research is to develop modifying admixtures to cement compositions based on local raw material - rock sand. Chemical and mineralogical properties of the source materials were studied using X-ray spectroscopy and X-ray diffraction analysis. Standard methods were used for defining physico-mechanical properties of sand and binder. Influence of the degree of mechanochemical activation of modifying admixture on the properties of binder and hardened cement paste made on its basis was studied. Research methods of scanning electron microscopy and spectral measurements were applied. The possibility of using admixture based on rock sand as a modifier was determined, its usage providing increase of strength, sulphate and frost resistance, which causes higher durability of cement concrete.

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.

Effect of Mixed Material on Sulphoaluminate Cement Sulfate Attack Resistance

2011 ◽  
Vol 306-307 ◽  
pp. 1101-1105
Author(s):  
Gui Yun Wang ◽  
Ling Chao Lu ◽  
Shou De Wang ◽  
Pi Qi Zhao
Keyword(s):  
Calcium Carbonate ◽  
Mechanical Performance ◽  
Resistance Coefficient ◽  
Sulfate Attack ◽  
Hardened Cement ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sulfate Resistance ◽  
Composition And Structure ◽  
Mixed Material

In order to enhance the ability of sulfate resistance of the coastal engineering, the effects of hydroxyapatite, shell and calcium carbonate on the mechanical performance and sulfate attack resistance were studied. The composition and structure of hardened cement paste were analyzed by means of X-ray diffraction and scanning electron microscopy. The experimental results showed that with the increase of mixed material contents, the compressive strength decreased, while the content of hydroxyapatite was 5%, the strength reached highest. The ability of sulfate resistance was improved as appropriate amounts of hydroxyapatite, shell and calcium carbonate were added into the cement. When the content of hydroxyapatite was 5%, the corrosion resistance coefficient was1.24, reaching the best resistance to sulfate attack.

Measuring Expansion Method on Sulfate Resistance Properties of Hardened Cement Paste

2011 ◽  
Vol 243-249 ◽  
pp. 4746-4749
Author(s):  
Xiu Juan Li ◽  
Jian Zhang
Keyword(s):  
Cement Paste ◽  
Expansion Method ◽  
Sulfate Solution ◽  
The United States ◽  
Sulfate Attack ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
Corrosion Properties ◽  
Sulfate Resistance ◽  
Complicated Process

Mechanism of sulfate attack is a very complicated process. In the laboratory, there are a variety of testing methods for cement resistance to sulfate attack. But there are still some problems. For example, the method often used in the United States Association standards and testing (ASTM) does indicate that expansion happens in the event of specimens’ breakage, but not point clearly the minimum amount of expansion leading to the strength damaged. In the present study, the method of measuring expansion of hardened cement paste sulfate resistance is discussed. It is found that experimental measurements can be used to study the erosion of sodium sulfate solution, but not be used to evaluate the anti-corrosion properties of hardened cement paste to magnesium sulfate.

Investigation of Sulphate Attack on C-S-H Gel

2011 ◽  
Vol 287-290 ◽  
pp. 1116-1120
Author(s):  
Xiao Xin Feng ◽  
Xiu Juan Li ◽  
Qing Min Wei
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Hardened Cement ◽  
Sulphate Attack ◽  
X Ray Diffraction ◽  
High Concentration ◽  
Hardened Cement Paste ◽  
X Ray ◽  
High Concentration Solution ◽  
Scanning Electron

C-S-H gel was prepared by extracting from the hardened cement paste, and was immersed in Na2SO4 solution and MgSO4 solution respectively. The microstructure of the C-S-H gel attacked by sulphate was observed by means of scanning electron microscopy, energy dispersive spectroscopy and X-ray diffraction. It is found that C-S-H gel is attacked by both Na2SO4 and MgSO4, and gypsum forms whether in low or high concentration solution of Na2SO4 and MgSO4.

scholarly journals Effect of Alkali Activator on the Standard Consistency and Setting Times of Fly Ash and GGBS-Based Sustainable Geopolymer Pastes

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
M. Dineshkumar ◽  
C. Umarani
Keyword(s):  
Fly Ash ◽  
Setting Time ◽  
Fluorescence Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Alkali Activator ◽  
Setting Times ◽  
Granulated Blast Furnace Slag ◽  
Ft Ir ◽  
Alkaline Activator

In this study, an attempt has been made to study the effect of alkali activator on the standard consistency and setting times of low calcium fly ash (FA) and ground granulated blast furnace slag (GGBS)- based sustainable geopolymer pastes. Different proportions of FA and GGBS were blended into mixes of geopolymer paste using sodium hydroxide (SH) and sodium silicate (SS) as alkaline activator solution (AAS). Tests on geopolymer pastes for consistency and initial and final setting times were carried out for three different SH : SS ratios of 1 : 1, 1 : 2, and 1 : 3 for both 2.5 M (molarity) and 5.0 M of SH concentration. While increasing the molarity of SH, both consistency and setting time decreased. For all the blended binder mix, the setting time decreases with an increase in the quantity of SS in the alkali activator solution. An increase in the amount of GGBS content in the geopolymer blended binder mix increases the consistency and decreases the setting time. For both 2.5 M and 5 M blended geopolymer mixes, a decrease in the percentage of GGBS and an increase in the percentage of FA increased the setting time. Microstructural studies such as X-ray fluorescence analysis (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FT-IR) analyses were carried out, and the results are presented. The FT-IR spectra for the blended binder mixes demonstrated the formation of geopolymerization and the presence of the functional groups.

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