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Open AccessArticle

SEM Image Analysis in Permeable Recycled Concretes with Silica Fume. A Quantitative Comparison of Porosity and the ITZ

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Faculty of Engineering Mochis, Autonomous University of Sinaloa, Fuente de Poseidón y Ángel Flores s/n, Col. Jiquilpan, Module B2, Los Mochis, Sinaloa 81210, Mexico
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Barcelona School of Building Construction, Polytechnic University of Catalonia, Av. Doctor Marañón 44-50, 08028 Barcelona, Spain
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Author to whom correspondence should be addressed.
Materials 2019, 12(13), 2201; https://doi.org/10.3390/ma12132201
Received: 4 June 2019 / Revised: 1 July 2019 / Accepted: 3 July 2019 / Published: 8 July 2019
(This article belongs to the Special Issue Properties and Novel Applications of Recycled Aggregates)
Recycled aggregates (RA) from construction and demolition can be used in permeable concretes (PC), improving the environment. PCs have a significant porous network, their cement paste and the interaction between the paste and the RA establishing their strength. Therefore, it is important to evaluate the porosity in the interfacial transition zones. The porosity of the cement paste, the aggregate and the interfacial transitional zones (ITZ) of a PC with recycled coarse aggregates (RCA) and silica fume (SF) is measured by means of image analysis–scanning electron microscope (IA)-(SEM) and by mapping the chemical elements with an SEM-EDS (energy dispersive spectrometer) detector microanalysis linked to the SEM and, as a contrast, the mercury intrusion porosimetry technique (MIP). In the IA process, a “mask” was created for the aggregate and another for the paste, which determined the porosity percentage (for the anhydrous material and the products of hydration). The results showed that using SF caused a reduction (32%) in the cement paste porosity in comparison with the PC with RA. The use of RA in the PC led to a significant increase (190%) in the porosity at different thicknesses of ITZ compared with the reference PC. Finally, the MIP study shows that the use of SF caused a decrease in the micropores, mesopores and macropores. View Full-Text
Keywords: porosity; recycled aggregates; permeable concrete; interfacial transition zone; image analysis; porosimetry mercury intrusion porosity; recycled aggregates; permeable concrete; interfacial transition zone; image analysis; porosimetry mercury intrusion
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MDPI and ACS Style

Chinchillas-Chinchillas, M.J.; Rosas-Casarez, C.A.; Arredondo-Rea, S.P.; Gómez-Soberón, J.M.; Corral-Higuera, R. SEM Image Analysis in Permeable Recycled Concretes with Silica Fume. A Quantitative Comparison of Porosity and the ITZ. Materials 2019, 12, 2201.

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