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.

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.

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 Effect of Limestone Powder on Thaumasite Form of Sulfate Attack (TSA) of Cement-Based Materials

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Yuxin Gao ◽  
Yaoling Luo ◽  
Lili Jia ◽  
Wen Yang ◽  
Chong Wang
Keyword(s):  
New Product ◽  
Sulfate Attack ◽  
Limestone Powder ◽  
Test Results ◽  
X Ray Diffraction ◽  
Cement Based Materials ◽  
Powder Content ◽  
Degradation Degree ◽  
The Relationship ◽  
Hydrated Calcium

Limestone powder can cause the thaumasite form of sulfate attack (TSA) of cement-based materials, but the relationship between the content of limestone powder and the degree of TSA is unclear. Hence, six different contents of limestone powder (0%, 5%, 10%, 15%, 30%, and 45%) were used to study the effect of the limestone powder content on the TSA of cement-based materials according to appearance and Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, X-ray diffraction (XRD), and chemical analyses. The test results indicated that limestone powder could promote sulfate attack. The formation of ettringite and gypsum was accelerated when the content of the limestone powder was not more than 10%. The degradation degree of the TSA was the most severe when the content of limestone powder was 30%. A new product, hydrated calcium carboaluminate, was found when the content of the limestone powder was 45%, and the degradation of the TSA was also delayed.

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.

scholarly journals Influence of Inertia and Low Active Mineral Admixture on Strength and Microstructure of Cement-Based Materials

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Meijuan Rao ◽  
Wan Tang ◽  
Wei Zhou ◽  
Yaning Kong ◽  
Shuhua Liu
Keyword(s):  
Fly Ash ◽  
Early Stage ◽  
Heat Of Hydration ◽  
Mineral Admixture ◽  
Limestone Powder ◽  
Mineral Admixtures ◽  
Inert Material ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cement Based Materials

Cement-based materials were investigated by comparing the strength and microstructure of pastes and mortar containing limestone powder or low quality fly ash. The compressive strength of the mortar at 28 and 90 d was examined whose microstructures were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis, and differential thermal analysis (TG-DTA). The results indicated that the strength of mortar decreased with increasing mineral admixtures. The limestone powder mainly acted as inert filler and hardly took part in the chemical reaction. Low quality fly ash may accelerate the formation of hydration products in samples with more chemically bonded water. This further resulted in a higher degree of cement hydration and denser microstructure, while the overall heat of hydration was reduced. At the early stage of hydration, low quality fly ash can be considered as an inert material whereas its reactivity at the later stage became high, especially for ground low quality fly ash.

Deterioration of Cement Pastes Containing Limestone Powder with Different Fineness Exposed to Sulfate Environment at Low Temperature

2013 ◽  
Vol 423-426 ◽  
pp. 1076-1080
Author(s):  
Feng Chen Zhang ◽  
Ruo Yu Tang ◽  
Yun Zhao
Keyword(s):  
Fourier Transform ◽  
Low Temperature ◽  
Sulfate Attack ◽  
Limestone Powder ◽  
Test Results ◽  
X Ray Diffraction ◽  
Limestone Filler ◽  
Cement Pastes ◽  
Cement Production ◽  
X Ray

Limestone filler and aggregates are used widely in cement production and concrete mixing nowadays, which could be connected with thaumasite formation, and lead to a lack of durability further in sulfate environment. This work deals with the deterioration of cement pastes containing 35% w/w limestone powder with different fineness immersed in MgSO4 solution at 5°C±2°C for 15 weeks by. Erosion phases are discussed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD). Test results show that visual deterioration of three kinds of cement pastes containing 400-mesh, 800-mesh and 1250-mesh limestone powders has little distinction, and erosion phases are all compound of ettringite, thaumasite, gypsum and brucite. Limestone powders with fineness of 400-mesh could supply enough carbonate needed for thaumastie formation. Increase of limestone fineness further could not accelerate deterioration of cement paste during the external magnesium sulfate attack at low temperature.

Effect of Initial Curing Conditions on Thaumasite Form of Sulfate Attack of Cement Based Materials

2013 ◽  
Vol 275-277 ◽  
pp. 2136-2140 ◽  
Author(s):  
Chang Hui Yang ◽  
Xiao Bin Xiang ◽  
Ben Wan Liu ◽  
Jing Zhang
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Sulfate Attack ◽  
X Ray Diffraction ◽  
Hydration Degree ◽  
Humid Air ◽  
Curing Conditions ◽  
X Ray ◽  
Cement Based Materials ◽  
Water Curing

The effects of initial high humid air-curing, standard water-curing and sealed-curing on thaumasite form of sulfate attack (TSA) of cement based materials were studied. The erosion products after three years attack in 5% MgSO4 solution were analyzed by means of X-ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). Initial high humid air-curing can delay the TSA of specimens for CaCO3 generated by carbonation and filled in the pores of the specimens, forming a compacted surface and restricting the intrusion of SO42-. In comparison, specimens cured in sealed condition occurred TSA most serious resulting from that large amount of inter-defects in specimens for the lower hydration degree, and SO42- ions could intrude into specimens more easily.

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.

Identification of acid-insoluble filter-plugging compounds and optimal acid-washing procedures for tubular backpulse pressure filters

TAPPI Journal ◽  
2011 ◽  
Vol 10 (1) ◽  
pp. 17-23
Author(s):  
KEVIN TAYLOR ◽  
RICH ADDERLY ◽  
GAVIN BAXTER
Keyword(s):  
Calcium Sulfate ◽  
Membrane Filter ◽  
Sulfamic Acid ◽  
Xrd Analysis ◽  
Metal Sulfides ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gypsum Formation ◽  
Acid Washing ◽  
Hydrolysis Of

Over time, performance of tubular backpulse pressure filters in kraft mills deteriorates, even with regular acid washing. Unscheduled filter replacement due to filter plugging results in significant costs and may result in mill downtime. We identified acid-insoluble filter-plugging materials by scanning electron microscope/energy-dispersion X-ray spectroscopy (SEM/EDS) and X-ray diffraction (XRD) analysis in both polypropylene and Gore-Tex™ membrane filter socks. The major filter-plugging components were calcium sulfate (gypsum), calcium phosphate (hydroxylapatite), aluminosilicate clays, metal sulfides, and carbon. We carried out detailed sample analysis of both the standard acid-washing procedure and a modified procedure. Filter plugging by gypsum and metal sulfides appeared to occur because of the acid-washing procedure. Gypsum formation on the filter resulted from significant hydrolysis of sulfamic acid solution at temperatures greater than 130°F. Modification of the acid-washing procedure greatly reduced the amount of gypsum and addition of a surfactant to the acid reduced wash time and mobilized some of the carbon from the filter. With surfactant, acid washing was 95% complete after 40 min.

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