Investigation of internal frost damage in cementitious materials with micromechanics analysis, SEM imaging and ultrasonic wave scattering techniques

2014 ◽  
Vol 50 ◽  
pp. 478-485 ◽  
Author(s):  
Kenny Ng ◽  
Ye Sun ◽  
Qingli Dai ◽  
Xiong Yu
Keyword(s):  
Ultrasonic Wave ◽  
Wave Scattering ◽  
Frost Damage ◽  
Cementitious Materials ◽  
Sem Imaging

Ultrasonic Wave Scattering by a Line Crack in a Solder Joint

1999 ◽  
Vol 11 (1) ◽  
pp. 117-135
Author(s):  
P. Dineva ◽  
D. Gross ◽  
T. Rangelov
Keyword(s):  
Solder Joint ◽  
Ultrasonic Wave ◽  
Wave Scattering ◽  
Line Crack

scholarly journals Effect of a Nitrite/Nitrate-Based Accelerator on the Strength Development and Hydrate Formation in Cold-Weather Cementitious Materials

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 1006
Author(s):  
Akira Yoneyama ◽  
Heesup Choi ◽  
Masumi Inoue ◽  
Jihoon Kim ◽  
Myungkwan Lim ◽  
...  
Keyword(s):  
Calcium Nitrate ◽  
Hydrate Formation ◽  
Frost Damage ◽  
Cementitious Materials ◽  
Heat Of Hydration ◽  
Cold Weather ◽  
Strength Development ◽  
Hardened Cement ◽  
Tricalcium Aluminate ◽  
Nitrite Nitrate

Recently, there has been increased use of calcium-nitrite and calcium-nitrate as the main components of chloride- and alkali-free anti-freezing agents to promote concrete hydration in cold weather concreting. As the amount of nitrite/nitrate-based accelerators increases, the hydration of tricalcium aluminate (C3A phase) and tricalcium silicate (C3S phase) in cement is accelerated, thereby improving the early strength of cement and effectively preventing initial frost damage. Nitrite/nitrate-based accelerators are used in larger amounts than usual in low temperature areas below −10 °C. However, the correlation between the hydration process and strength development in concrete containing considerable nitrite/nitrate-based accelerators remains to be clearly identified. In this study, the hydrate composition (via X-ray diffraction and nuclear magnetic resonance), pore structures (via mercury intrusion porosimetry), and crystal form (via scanning electron microscopy) were determined, and investigations were performed to elucidate the effect of nitrite/nitrate-based accelerators on the initial strength development and hydrate formation of cement. Nitrite/nitrate-AFm (aluminate-ferret-monosulfate; AFm) was produced in addition to ettringite at the initial stage of hydration of cement by adding a nitrite/nitrate-based accelerator. The amount of the hydrates was attributed to an increase in the absolute amounts of NO2− and NO3− ions reacting with Al2O3 in the tricalcium aluminate (C3A phase). Further, by effectively filling the pores, it greatly contributed to the enhancement of the strength of the hardened cement product, and the degree of the contribution tended to increase with the amount of addition. On the other hand, in addition to the occurrence of cracks due to the release of a large amount of heat of hydration, the amount of expansion and contraction may increase, and it is considered necessary to adjust the amount used for each concrete work.

Ultrasonic wave scattering from fiber–matrix interphases

1995 ◽  
Vol 97 (2) ◽  
pp. 807-817 ◽  
Author(s):  
W. Huang ◽  
S. Brisuda ◽  
S. I. Rokhlin
Keyword(s):  
Ultrasonic Wave ◽  
Wave Scattering ◽  
Fiber Matrix

scholarly journals Ultrasonic wave scattering from solids with periodic surfaces: Theory and experiment

1982 ◽  
Vol 71 (S1) ◽  
pp. S44-S44 ◽  
Author(s):  
Alain Jungman ◽  
Laszlo Adler ◽  
Robert Roberts ◽  
Jan Achenbach
Keyword(s):  
Ultrasonic Wave ◽  
Wave Scattering ◽  
Periodic Surfaces ◽  
Theory And Experiment
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