Deterioration of Mortar Composites in Acidic Environment

2014 ◽  
Vol 1064 ◽  
pp. 3-8 ◽  
Author(s):  
M. Omrane ◽  
M. Mouli ◽  
A.S. Benosman ◽  
Y. Senhadji
Keyword(s):  
Experimental Study ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Acidic Environment ◽  
Acid Solutions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Aggressive Environment ◽  
Chemical Attack ◽  
Acidic Environments

In recent years, the rapid deterioration of various reinforced concrete structures has been widely recognized as worldwide problem. Acidic environments are very aggressive to concrete structures, as well as promote their degradation. The aim of this experimental study is to make a comparative analysis of the behavior of mortars prepared by cement (CPJ-CEM II/A) and composites of different percentage by weight of polymer. It highlights the influence of PET on the durability of these mortars. After 28 days of curing specimens in water, they are put in acid solutions of the same concentration 3% (HCl, H2SO4, H3PO4and HNO3). Weights tests measuring are made ​​at different ages. The results demonstrate the beneficial effect of the addition of PET in the modified materials against chemical attack by various acids. The formations which appear such as different calcium salts were determined by X-ray diffraction. These results take into account the recycling of plastic waste in the manufacture of modified mortars against aggressive environment.

High-Temperature Corrosion Performance of FeAl-Based Alloys Containing Carbon in Molten Salt

Metals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 2040
Author(s):  
Munish Kumar ◽  
Ravi Kant ◽  
Suresh Chand ◽  
Ujjwal Prakash ◽  
Shankar Sehgal ◽  
...  
Keyword(s):  
Corrosion Behavior ◽  
Molten Salts ◽  
Corrosion Performance ◽  
X Ray Diffraction ◽  
Corrosive Media ◽  
Al2o3 Layer ◽  
X Ray ◽  
Aggressive Environment ◽  
Arc Melting ◽  
Ti Addition

Corrosion behavior of FeAl-based alloys containing carbon produced through arc melting in argon atmosphere has been studied at 500 °C to 700 °C. The samples were tested in the aggressive environment of molten salts (80%V2O5/20%Na2SO4). The corrosion behavior was observed by weight change method and the layer products formed were examined by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive spectroscopy (EDS). The different phase components were observed in the surface layer after the test in Fe-22Al alloy. A protective Al2O3 layer was confirmed for Fe-22Al alloy containing carbon only. However, an additional TiO layer was also observed in Fe-22Al alloy containing carbon with Ti addition. The microstructural and XRD examinations revealed that this additional TiO layer protects better against penetration of corrosive media. The corrosion resistance behavior of FeAl-based alloys were addressed on the basis of microstructural evidence.

EXPERIMENTAL STUDY OF THE HIGH Tc SUPERCONDUCTOR Y-Ba-Cu-O SYSTEM

1989 ◽  
Vol 03 (08) ◽  
pp. 661-664
Author(s):  
S.M.M.R. NAQVI ◽  
JAWAID ALAM ◽  
FIROZ AHMAD ◽  
MUSHEER HASAN KHAN
Keyword(s):  
Experimental Study ◽  
Superconducting Phase ◽  
X Ray Diffraction ◽  
High Tc ◽  
X Ray ◽  
High Tc Superconductor ◽  
Zero Resistance

Two batches of Y-Ba-Cu-O superconductors have been prepared. The zero resistance temperature is 90 K with Tc onset at 93 K and 95 K, respectively. Susceptibility measurements show superconducting phase at LN2. X-ray diffraction results indicates single phases.

scholarly journals Different Setting Conditions Affect Surface Characteristics and Microhardness of Calcium Silicate-Based Sealers

Scanning ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Dong-Kyu Yang ◽  
Sunil Kim ◽  
Jeong-Won Park ◽  
Euiseong Kim ◽  
Su-Jung Shin
Keyword(s):  
Calcium Silicate ◽  
Detrimental Effect ◽  
Surface Characteristics ◽  
Storage Conditions ◽  
Acid Solutions ◽  
X Ray Diffraction ◽  
Surface Microhardness ◽  
X Ray ◽  
Phosphate Buffered Saline ◽  
Scanning Electron

Objective. To investigate the effect of different setting conditions on surface microhardness and setting properties of calcium silicate-based sealers. Methods. Three sealers, EndoSequence Bioceramic (BC; Brasseler USA, Savannah, GA, USA), Endoseal MTA (ES; Maruchi, Wonju, Korea), and Well-Root ST (WR; Vericom, Chuncheon, Korea), were compared. Specimens were exposed to either butyric acid (pH 5.4) or phosphate-buffered saline (PBS [pH 7.4]) for 48 h and stored at 100% humidity for 12 days. The control specimens were stored at 100% humidity for 14 days. Surface microhardness was measured, topographic changes were observed, and phase analysis was performed using X-ray diffraction. Microhardness according to storage conditions was compared using one-way analysis of variance and Tukey’s multiple comparison tests (P<.05). Results. The BC and ES sealers exhibited decreased microhardness when stored in acid or PBS compared with control (P<.05). In the WR group, acid exposure lowered microhardness of the specimens compared with control (P<.05). Scanning electron microscopy revealed different topographies in specimens from all tested sealers exposed to acid or PBS. Conclusion. The surface microhardness of calcium silicate-based sealers was reduced by exposure to either acid or PBS. Acid solutions, however, had a more detrimental effect than PBS.

Experimental Study on Combustion Reaction between Silicon and Nitrogen in Transport Bed

2013 ◽  
Vol 860-863 ◽  
pp. 1374-1377
Author(s):  
Shao Wu Yin ◽  
Li Wang ◽  
Li Ge Tong ◽  
Chuan Ping Liu ◽  
Xing Long Zheng
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Experimental Study ◽  
Reaction Time ◽  
Reaction Temperature ◽  
Combustion Reaction ◽  
X Ray Diffraction ◽  
Amorphous Silicon Nitride ◽  
X Ray ◽  
Scanning Electron

Combustion reaction between silicon powders and nitrogen in transport bed was studied. The reaction temperature ranged from 1523 to 1653 K, and the reaction time ranged from 0 to 2.7 min. The phase compositions, morphologies and chemical composition of the products were analyzed by X-ray diffraction, scanning electron microscopy and O/N determinater, respectively. The experimental results showed, in the case of silicon powders with particle size of 2.2 μm, the conversion rate of silicon was 61.9% at reaction temperature of 1653 K and reaction time of 2.7min, and the products mainly comprised amorphous silicon nitride powders.

Experimental Study of Concrete Class Influence on Cracks Spacing

2014 ◽  
Vol 600 ◽  
pp. 558-568
Author(s):  
Omar Zorkane ◽  
Farid Chalah ◽  
Lila Chalah-Rezgui ◽  
Abderrahim Bali ◽  
Mohamed Nadib Oudjit
Keyword(s):  
Experimental Study ◽  
Reinforced Concrete ◽  
Phase Ii ◽  
Normal State ◽  
Limit State ◽  
Concrete Structures ◽  
Reinforced Concrete Structures ◽  
Limit States ◽  
Continuous Beams ◽  
Real Size

The aim of this work is to study the cracking of reinforced concrete continuous beams by considering different classes of concrete. It is well known that the design of reinforced concrete structures includes three limit states (limit state of collapse, limit state of strain and limit state of cracking). The cracks in reinforced concrete structures are admitted in the phase II (cracked sections). Thus, the phenomenon of cracks formation can be treated as a normal state only when their openings are limited to avoid a permanent risk of collapse and ensure durability for the civil engineering concrete structures. The importance of this work is described by the tests made on reinforced concrete continuous beams in real size, under concentrated loads increasing from zero up to collapse, where the concrete class influence on the cracks spacing has been studied. As this wasnt theoretically investigated, the used references for an aim comparison were relative to experimentations made by Monnier and Kuczynski on an only one concrete class to the cracks openings and the spacing evaluation analysis The findings of the research reported in this paper show that there is no effect of the concrete class on the cracks spacing.

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