scholarly journals Elucidating the Effect of Accelerated Carbonation on Porosity and Mechanical Properties of Hydrated Portland Cement Paste Using X-Ray Tomography and Advanced Micromechanical Testing

Micromachines ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 471 ◽  
Author(s):  
Hongzhi Zhang ◽  
Claudia Romero Rodriguez ◽  
Hua Dong ◽  
Yidong Gan ◽  
Erik Schlangen ◽  
...  
Keyword(s):  
Elastic Modulus ◽  
Cement Paste ◽  
Total Porosity ◽  
Correlation Study ◽  
Accelerated Carbonation ◽  
X Ray ◽  
Micromechanical Properties ◽  
Hydrated Cement Paste ◽  
X Ray Computed ◽  
Beam Bending

Carbonation of hydrated cement paste (HCP) causes numerous chemo–mechanical changes in the microstructure, e.g., porosity, strength, elastic modulus, and permeability, which have a significant influence on the durability of concrete structures. Due to its complexity, much is still not understood about the process of carbonation of HCP. The current study aims to reveal the changes in porosity and micromechanical properties caused by carbonation using micro-beam specimens with a cross-section of 500 μm × 500 μm. X-ray computed tomography and micro-beam bending tests were performed on both noncarbonated and carbonated HCP micro-beams for porosity characterization and micromechanical property measurements, respectively. The experimental results show that the carbonation decreases the total porosity and increases micromechanical properties of the HCP micro-beams under the accelerated carbonation. The correlation study revealed that both the flexural strength and elastic modulus increase linearly with decreasing porosity.

Density mapping of hardened cement paste using ptychographic X-ray computed tomography

2013 ◽  
Vol 36 ◽  
pp. 71-77 ◽  
Author(s):  
Pavel Trtik ◽  
Ana Diaz ◽  
Manuel Guizar-Sicairos ◽  
Andreas Menzel ◽  
Oliver Bunk
Keyword(s):  
Computed Tomography ◽  
Cement Paste ◽  
Hardened Cement ◽  
Hardened Cement Paste ◽  
X Ray ◽  
Density Mapping ◽  
X Ray Computed

Effect of Fly Ash on the early Age Cracking Performance of Cement Paste

2014 ◽  
Vol 584-586 ◽  
pp. 894-898
Author(s):  
Ping Zhang ◽  
Guan Guo Liu ◽  
Chao Ming Pang ◽  
Bing Du ◽  
Hong Gen Qin
Keyword(s):  
Computed Tomography ◽  
Fly Ash ◽  
Cement Paste ◽  
Test Method ◽  
Early Age ◽  
Cement Ratio ◽  
X Ray ◽  
Cracking Performance ◽  
X Ray Computed ◽  
Ct Test

The X ray computed tomography (X-CT) was applied to test the cracking resistance of cement paste, and the hydration process was monitored to study the effect of fly ash on the early age cracking performance. The results showed that the hydration heat reduced with the increase of fly ash under the same water-cement ratio. Within 24h, the porosity increased with time. The addition of fly ash increased the proportion of large holes and then changed the internal stress state. Using X-CT test method and by comparing the number of cracks, the sample with 20% FA was found to have the most serious cracks, whereas the sample with 30% FA had the best crack resistance.

Visualization of Penetration of NanoSiO2 into Cement Paste Using X-ray Computed Tomography

2018 ◽  
Vol 10 (1) ◽  
pp. 135-137
Author(s):  
Yue Gu ◽  
Qianping Ran ◽  
Zhenhua Wei ◽  
Wei She ◽  
Jiaping Liu
Keyword(s):  
Computed Tomography ◽  
Cement Paste ◽  
X Ray ◽  
X Ray Computed

The effect of storage time and repeated measurements on the elastic properties of isolated porcine aortas using high resolution x-ray CT

1998 ◽  
Vol 76 (4) ◽  
pp. 451-456 ◽  
Author(s):  
Andrew O Medynsky ◽  
David W Holdsworth ◽  
Marvin H Sherebrin ◽  
Richard N Rankin ◽  
Margot R Roach
Keyword(s):  
Elastic Modulus ◽  
Storage Time ◽  
Repeated Measurements ◽  
Ct Scanner ◽  
Imaging Studies ◽  
X Ray ◽  
X Ray Computed ◽  
Significant Change ◽  
Humidified Air ◽  
Ct Measurement

A Laboratory CT scanner with a resolution of (0.1 mm)3 wasused to determine if storage up to 7 days in saline at 4°C and (or) repeated measurementswould alter the compliance, C, and incremental elastic modulus, Einc,of isolated porcine aortas. All specimens were obtained fresh, made pressure-tight, and thenmounted in the scanner, with humidified air used to produce adequate x-ray contrast. Thespecimens were imaged at pressures of 4, 8, 12, 16, 20, and 24 kPa, and vessel measurementswere then obtained with a computerized technique and analyzed. Seven thoracic aortas werestudied on days 0, 3, 5, and 7, with a significant change (p < 0.05) in compliance firstoccurring after three imaging studies (i.e., day 5). Compliance of the fresh thoracic aortas (mean± SD) was 0.90 ± 0.28 mm/kPa at 14.4 kPa and 0.85 ± 0.31 mm/kPa at 22.5 kPa.Six thoracic aortas were studied only on days 0 and 6 with no intermediate measurements. Theyshowed no change in either compliance (0.88 ± 0.07 mm/kPa at 14.4 kPa and 0.64 ±0.09 mm/kPa at 22.5 kPa) or Einc (0.46 ± 0.05 MPa at14.4 kPa and 0.88 ± 0.15 MPa at 22.5 kPa) from day 0 to day 6. Thus, number ofmeasurements rather than time appears to be the important factor. Six abdominal aortas werestudied similarly but on days 0, 3, and 6. No significant change occurred in compliance (0.15 ±0.06 mm/kPa at 14.4 kPa and 0.032 ± 0.026 mm/kPa at 22.5 kPa) butEinc showed a change, possibly due to their viscoelastic properties. Weconclude that this nondestructive CT measurement method is suitable for repeated studies onporcine thoracic aortas, but not abdominal aortas, if the measurement involves two consecutiveimaging sessions separated by no more than 6 days.Key words: compliance, incremental elastic modulus, porcine aorta,x-ray computed tomography.

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