scholarly journals Effect of Cellulose Nanocrystals on the Properties of Cement Paste

2019 ◽  
Vol 2019 ◽  
pp. 1-7
Author(s):  
Qiaoling Liu ◽  
Yujiao Peng ◽  
Long Liang ◽  
Xiaobin Dong ◽  
Hancai Li
Keyword(s):  
Cement Paste ◽  
Cellulose Nanocrystals ◽  
Nitrogen Adsorption ◽  
Cement Matrix ◽  
Size Distributions ◽  
Cement Pastes ◽  
Curing Conditions ◽  
X Ray ◽  
Pore Size Distributions ◽  
X Ray Computed

The effect of the addition of cellulose nanocrystals (CNCs) on the properties of cement pastes is studied herein. The compressive strength of CNC/cement paste was investigated under the curing conditions defined in this study. Two-dimensional micrographs and pore size distributions were obtained by scanning electron microscopy, X-ray computed tomography (XCT), and nitrogen adsorption. The addition of CNCs was found to significantly enhance the mechanical properties of cement pastes with a rapid decrease in temperature and humidity. XCT and nitrogen adsorption analyses show that the addition of CNCs leads to a refinement of the pore structure in the cement matrix. Almost no hydration products, including C-S-H, are formed in the cement matrix without CNCs under extreme conditions. This is in contrast with the results for the cement paste with 0.5% CNCs.

A New X-Ray Scattering Method for Determining Pore-Size Distribution in Low-k Thin Films

2001 ◽  
Vol 714 ◽  
Author(s):  
Kazuhiko Omote ◽  
Shigeru Kawamura
Keyword(s):  
Thin Films ◽  
Pore Size Distribution ◽  
Pore Size ◽  
Gas Adsorption ◽  
Size Distributions ◽  
X Ray ◽  
X Ray Scattering ◽  
Pore Size Distributions ◽  
Scattering Technique ◽  
Ray Scattering

ABSTRACTWe have successively developed a new x-ray scattering technique for a non-destructive determination of pore-size distributions in porous low-κ thin films formed on thick substrates. The pore size distribution in a film is derived from x-ray diffuse scattering data, which are measured using offset θ/2θ scans to avoid strong specular reflections from the film surface and its substrate. Γ-distribution mode for the pores in the film is used in the calculation. The average diameter and the dispersion parameter of the Γ-distribution function are varied and refined by computer so that the calculated scattering pattern best matches to the experimental pattern. The technique has been used to analyze porous methyl silsesquioxane (MSQ) films. The pore size distributions determined by the x-ray scattering technique agree with that of the commonly used gas adsorption technique. The x-ray technique has been also used successfully determine small pores less than one nanometer in diameter, which is well below the lowest limit of the gas adsorption technique.

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.

scholarly journals Pore Structure Damages in Cement-Based Materials by Mercury Intrusion: A Non-Destructive Assessment by X-Ray Computed Tomography

Materials ◽  
2019 ◽  
Vol 12 (14) ◽  
pp. 2220 ◽  
Author(s):  
Xiaohu Wang ◽  
Yu Peng ◽  
Jiyang Wang ◽  
Qiang Zeng
Keyword(s):  
Computed Tomography ◽  
Pore Structure ◽  
High Mass ◽  
X Ray ◽  
Quantitative Evidence ◽  
Mercury Intrusion ◽  
Pore Size Distributions ◽  
Cement Based Materials ◽  
Before And After ◽  
X Ray Computed

Mercury intrusion porosimetry (MIP) is questioned for possibly damaging the micro structure of cement-based materials (CBMs), but this theme still has a lack of quantitative evidence. By using X-ray computed tomography (XCT), this study reported an experimental investigation on probing the pore structure damages in paste and mortar samples after a standard MIP test. XCT scans were performed on the samples before and after mercury intrusion. Because of its very high mass attenuation coefficient, mercury can greatly enhance the contrast of XCT images, paving a path to probe the same pores with and without mercury fillings. The paste and mortar showed the different MIP pore size distributions but similar intrusion processes. A grey value inverse for the pores and material skeletons before and after MIP was found. With the features of excellent data reliability and robustness verified by a threshold analysis, the XCT results characterized the surface structure of voids, and diagnosed the pore structure damages in terms of pore volume and size of the paste and mortar samples. The findings of this study deepen the understandings in pore structure damages in CBMs by mercury intrusion, and provide methodological insights in the microstructure characterization of CBMs by XCT.

X-Ray computed tomography and traditional analysis of a capillary absorption test in cement pastes

2020 ◽  
Vol 113 ◽  
pp. 103634
Author(s):  
Carmen Andrade ◽  
Luis Saucedo ◽  
Nuria Rebolledo ◽  
Sandra Cabeza ◽  
Dietmar Meinel
Keyword(s):  
Computed Tomography ◽  
Capillary Absorption ◽  
Absorption Test ◽  
Cement Pastes ◽  
X Ray ◽  
X Ray Computed
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