Microstructure and Durability of RC in Boric Acid

2011 ◽  
Vol 250-253 ◽  
pp. 252-256
Author(s):  
Hui Zhen Jin ◽  
Qiang Li ◽  
Xian Yu Jin ◽  
Ye Tian ◽  
Nan Guo Jin
Keyword(s):  
Boric Acid ◽  
Nuclear Power ◽  
Acid Corrosion ◽  
Hydration Product ◽  
Concrete Surface ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
Acid Environment ◽  
Scanning Electron

Boric acid (H3BO3) is often used for cooling the heat in nuclear power plant. Though the drastic measures have been taken, the potential leakage still can not be fully eliminated. Therefore, an attempt to understand the durability mechanism of RC subjected to boric acid is of vital importance. In this paper, specimens cured in a standard moist room at a temperature of 20 ±3 °C after 28days were immersed in three different concentration of boric solution (2000ppm, 8000ppm, 30000ppm) artificially simulated to accelerate the corrosion of acid environment. The hydration products are investigated. Microstructure of reinforced concrete on the surface, 2cm and 4cm away from the surface at ages of 60, 90 and 150 days are examined using X-ray diffraction (XRD) and scanning electron microscope (SEM) respectively. Results indicate that main hydration product is Ca(BO2)2,boric acid corrosion to concrete surface can only be detected from the specimens in 30000ppm solutions at the ages of 150 days and its effect is slight. However, the inner part of the concrete was not affected. The results of XRD coincide with those of SEM.

Experimental Research on High-Strength Super Sulphate Cement Paste Mixed with Superfine Mineral Admixtures

2014 ◽  
Vol 629-630 ◽  
pp. 150-155
Author(s):  
Jun Wang ◽  
Bao Ying Yu ◽  
Long Yang ◽  
Yu Xin Gao ◽  
Jia Yu Xiang
Keyword(s):  
Silica Fume ◽  
High Strength ◽  
Hydration Product ◽  
Mineral Admixtures ◽  
Hydration Reaction ◽  
X Ray Diffraction ◽  
Cement Ratio ◽  
X Ray ◽  
Early Strength ◽  
Scanning Electron

Aimed at the performance affect of high-strength super sulphate cement (SSC) paste mixed with superfine mineral admixtures, influence of microbead and silica fume replacing SSC quantity on high-strength SSC paste compression strength were studied under water-cement ratio 0.18; Hydration product morphology and phase were further compared by scanning electron microscopy and X-ray diffraction analyzer in this paper. Results show that, compared with sample HS-1, 3-day strength of HS-2 and HS-3 were increased by 5% and 10%, 28d strength basically unchanged; Furthermore, early strength of HS-7 sample slightly higher and late strength basically unchanged. SSC by adding 5% microbead and 3% silica fume (HS-11) has compressive strength 50.8MPa at 3 days and 86.1MPa at 28 days is significantly higher than other samples. Early strength of HS-11sample mainly depends on hydration reaction of SSC and particle filling effect of admixtures, later strength is due to accelerating consumption of gypsum and promoting formation of ettringite.

scholarly journals Evaluation of the Properties of Cemented Liquid Scintillator Wastes under Flooding Scenario in Various Aqueous Media

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
H. El-Didamony ◽  
T. A. Bayoumi ◽  
M. I. Sayed
Keyword(s):  
Electron Microscopy ◽  
Liquid Scintillator ◽  
Aqueous Media ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
Long Period ◽  
Flooding Event ◽  
Predetermined Interval ◽  
Scanning Electron

Experiments simulating flooding scenario in various aqueous media for a long period were carried out to determine the adequacy of cement-clay composite for solidification/stabilization of spent organic radioactive liquid scintillator wastes. The final cement waste form blocks were immersed in three aqueous media, namely, seawater, groundwater, and tapwater. The immersion process lasted for increasing periods up to 540 days. Following each predetermined interval period, physical and mechanical evaluations of the immersed blocks were determined. In addition, the change in the hydration products was followed by X-ray diffraction and infrared spectroscopy as nondestructive analyses to recognize the deterioration in the microstructure that may occur due to the flooding event. Thermal analysis and scanning electron microscopy were performed to confirm the data obtained.

Effect of Aluminum Insertion Material on the Properties of AAC

2016 ◽  
Vol 703 ◽  
pp. 406-410
Author(s):  
Yun Feng Pan ◽  
Wan Ming Huang ◽  
Ya Qing Jiang ◽  
Qiang Song
Keyword(s):  
Volume Ratio ◽  
High Strength ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Hydration Degree ◽  
Scanning Electron Microscope Analysis ◽  
X Ray ◽  
Electron Microscope Analysis ◽  
Aerated Concrete ◽  
Scanning Electron

Study on the compressive strength, shrinkage and effect of aluminum insertion materials on the hydration products of Autoclaved Aerated Concrete (AAC). The types and properties of hydration products are studied by X-Ray Diffraction Analysis (XRD), Differential Thermal Analysis (DTA), Scanning Electron Microscope analysis (SEM) and so on. The results showed that the strength and the shrinkage resistance capability of the product could be improved effectively. Al3+successfully doped into C-S-H gel and tobermorite crystals, then replaced si4+of tobermorite and formed the system of C-A-S-H. Tobermorite in aluminum insertion aerated concrete is smaller and more compact. All hydration products interlace to form a whole, then the structure turns denser. Low porosity, high crystal gel volume ratio and high hydration degree are the key of the high strength aluminum insertion aerated concrete. Aluminum insertion materials improve the performance of the products.

Study on the Behavior and Durability of Reinforced Concrete in Boric Acid Environment

2008 ◽  
Vol 400-402 ◽  
pp. 441-446 ◽  
Author(s):  
Xian Yu Jin ◽  
Nan Guo Jin ◽  
Ye Tian
Keyword(s):  
Reinforced Concrete ◽  
Acid Solution ◽  
Boric Acid ◽  
Diffraction Analysis ◽  
Boric Acid Solution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Weight Losses ◽  
Steel Bars ◽  
Acid Environment

By method of artificial simulating acid environment to celebrating corrosion, the effects of boric acid on the physical properties and performance of reinforced concrete were investigated. The experimental study of concrete in nature and in various boric solutions (2000ppm, 8000ppm, 30000ppm) was carried out. The compressive strength, splitting tensile strength and elastic modulus of concrete were measured. The weight losses of steel bars and bond strength of reinforced concrete were calculated to analysis the influence of boric acid on reinforced bars. The ingredient change of concrete submerged in boric acid solution was studied with X-ray diffraction analysis. The experiments show that, in general, the mechanical strength of corrupted concrete increases with time. While comparing to the specimen curried in nature environment, the fundamental properties of concrete in boric acid solution decrease slightly. In this research, the influence of boric acid on the corrosion of the steel bars and the interacting between the concrete and the steel bars are insignificant. Three kinds of borides are detected in the X-ray diffraction analysis. It can be concluded from the research that boric acid will not generate apparent influence on the mechanics performance of concrete and steel bars. The same conclusion can be drawn on the bond properties between concrete and steel bars. Generally, corrosiveness of boric acid to reinforced concrete is quite weak.

scholarly journals Effect of Metakaolin on Strength and Efflorescence Quantity of Cement-Based Composites

2013 ◽  
Vol 2013 ◽  
pp. 1-11 ◽  
Author(s):  
Tsai-Lung Weng ◽  
Wei-Ting Lin ◽  
An Cheng
Keyword(s):  
Compressive Strength ◽  
Image Analysis ◽  
Portland Cement ◽  
Detrimental Effect ◽  
Cement Mortar ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Replacement Ratio ◽  
X Ray ◽  
Scanning Electron

This study investigated the basic mechanical and microscopic properties of cement produced with metakaolin and quantified the production of residual white efflorescence. Cement mortar was produced at various replacement ratios of metakaolin (0, 5, 10, 15, 20, and 25% by weight of cement) and exposed to various environments. Compressive strength and efflorescence quantify (using Matrix Laboratory image analysis and the curettage method), scanning electron microscopy, and X-ray diffraction analysis were reported in this study. Specimens with metakaolin as a replacement for Portland cement present higher compressive strength and greater resistance to efflorescence; however, the addition of more than 20% metakaolin has a detrimental effect on strength and efflorescence. This may be explained by the microstructure and hydration products. The quantity of efflorescence determined using MATLAB image analysis is close to the result obtained using the curettage method. The results demonstrate the best effectiveness of replacing Portland cement with metakaolin at a 15% replacement ratio by weight.

The Study of Alkaline-Activated Magnesium Slag Cementitious Material

2012 ◽  
Vol 517 ◽  
pp. 363-366 ◽  
Author(s):  
Li Guang Xiao ◽  
Feng Luo ◽  
Rui Bo Li ◽  
Chang Yu Liu
Keyword(s):  
Electron Microscopy ◽  
Mechanical Property ◽  
Interaction Mechanism ◽  
Cementitious Materials ◽  
Cementitious Material ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
Furnace Slag ◽  
Scanning Electron

Magnesium slag cementitious material was prepared successfully using the magnesium slag-furnace slag-clinker system and different activators in this paper. The effect of activator on the mechanical property of the material was studied. The hydration and microstructure of this composite cement were analyzed by X-ray diffraction and scanning electron microscopy and the interaction mechanism was researched. The results show that the activity of magnesium slag was enhanced significantly by adding a small amount of activator. Combined activators have the best effect. The hydration products of magnesium slag cementitious materials mortar were C-S-H, Aft and Ca (OH)2 and so on.

scholarly journals Chemical corrosion of external stairs – case study

2018 ◽  
Vol 163 ◽  
pp. 05003 ◽  
Author(s):  
Przemysław Czapik ◽  
Zdzisława Owsiak
Keyword(s):  
Phase Composition ◽  
Concrete Surface ◽  
Corrosion Process ◽  
Alkali Silica Reaction ◽  
X Ray Diffraction ◽  
Chemical Corrosion ◽  
X Ray ◽  
Concrete Corrosion ◽  
Scanning Electron

On the basis of examinations of the efflorescences formed on the concrete surface, an attempt was made to analyze the sources of concrete corrosion without entering inside the construction. The concrete stairs revealed the symptoms of leaching, as a result of alkali-aggregate reactions developing beneath the surface. As a result of this corrosion process and the carbonation propagating from the concrete surface, the carbonate efflorescences were found. Their phase composition was determined by X-ray diffraction. In order to identify whether the efflorescences were the results of the alkali-silica reaction or alkalicarbonate reaction, the microstructure was investigated using the scanning electron microscope together with energy dispersive spectroscopy.

Utilization of Desulfuration Residues in Non-Autoclaved Aerated Concrete

2011 ◽  
Vol 250-253 ◽  
pp. 707-710
Author(s):  
Fang Xian Li ◽  
You Zhi Chen ◽  
Qi Jun Yu ◽  
Jiang Xiong Wei
Keyword(s):  
Compressive Strength ◽  
Electron Microscope ◽  
Scanning Electron Microscope ◽  
Bulk Density ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
X Ray ◽  
Autoclaved Aerated Concrete ◽  
Aerated Concrete ◽  
Scanning Electron

Desulfuration residues were used as aggregate to produce Non-autoclaved aerated concrete. The effects of water-hinder ratio, casting temperature on the gas forming behavior, and those of desulfuration residue content on the compressive strength and bulk density of aerated concrete were investigated. The types of the hydration products and the microstructure of Non-autoclaved aerated concrete with desulfuration residue were investigated by means of X-ray diffraction and scanning electron microscope. Results show that the optimum replacement amount was determined as 50% and at this rate the compressive strength, bulk density of Non-autoclaved aerated concrete were measured as 2.83 MPa and 543 kg/m3. The hydration products of Non-autoclaved aerated concrete with desulfuration residue are C2SH (A) and C2SH (B) along with ettringite and hydrogarnet phases.

Fly Ash-Calcined Phosphogypsum Cementitous Materials with Different Thermally Treated Phosphogypsum

2011 ◽  
Vol 261-263 ◽  
pp. 816-819 ◽  
Author(s):  
Min Yang ◽  
Qing Chen Sun
Keyword(s):  
Electron Microscopy ◽  
Fly Ash ◽  
Strength Development ◽  
Hydration Products ◽  
X Ray Diffraction ◽  
Curing Conditions ◽  
X Ray ◽  
Scanning Electron ◽  
Thermally Treated

Experiments were performed to investigate the properties of fly ash-calcined phosphogypsum (PG) cementitous materials with PG different thermally treated, including being calcined at 135°C, 430°C and 800°C separately. Durability of the cementitous materials was investigated by determination of mass loss of binders immersed in water for different durations and strength development subjected to various curing conditions. X-ray diffraction analysis was used to study the differences in hydration products among binders with different thermally treated PG. Morphology and microstructure of the hardened binders were investigated by scanning electron microscopy. Results suggest that the binder with PG sintered at 430°C obtains the best performance, indicating both impurities in PG and the form of gypsum influence its utilization greatly. Considering this, it can be concluded that choice of a proper thermal treatment is important.

scholarly journals Effects of EDTA and Boric Acid on the Morphology ofCaCO3Particles

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
Xingbo Shi ◽  
Julin Wang ◽  
Xiaoping Cai
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Acid Solution ◽  
Boric Acid ◽  
Room Temperature ◽  
Boric Acid Solution ◽  
Tetraacetic Acid ◽  
X Ray Diffraction ◽  
X Ray ◽  
Scanning Electron

Calcium carbonate (CaCO3) particles with different morphologies were prepared using calcium chloride (CaCl2) and sodium carbonate (Na2CO3) aqueous solutions containing various amounts of ethylenediamine tetraacetic acid (EDTA) or boric acid. The products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The sphere-like CaCO3particle was inclined to be formed in EDTA or boric acid solution at room temperature. The surface of CaCO3is smooth in the presence of EDTA, and the crystal structure of CaCO3is majorly vaterite. However, the CaCO3has a rough surface in boric acid solution and pure calcite structure. The size of CaCO3particle decreases with the increase in the amount of EDTA or boric acid.

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