2026-04-17T20:35:28Zhttps://riubu.ubu.es/oai/request

oai:riubu.ubu.es:10259/100732025-01-30T01:05:48Zcom_10259_4809com_10259_5086com_10259_2604col_10259_4810

Influence of air-entraining agent and freeze-thaw action on pore structure in high-strength concrete by using CT-Scan technology González Cabrera, Dorys Carmen Mena Alonso, Álvaro Mínguez Algarra, Jesús Vicente Cabrera, Miguel Ángel Computed tomography Air-entraining agent Freeze-thaw cycles High-strength concrete Pore structure Pore distribution Ingeniería civil Materiales de construcción Resistencia de materiales Civil engineering Building materials Strength of materials In this work, the effects caused by both the amount of air-entraining agent (AEA) and freeze-thaw cycles on microstructure of high-strength concrete have been analyzed. For this purpose, five series of concrete specimens have been manufactured, each of them containing a different amount of AEA. Then, all series have been subjected to up to 300 freeze-thaw cycles. In addition, the specimens have been analyzed using a computed tomography (CT) scan device at pre-defined freeze-thaw cycles and all data have been processed with digital image processing (DIP) software. The results reveal, on the one hand, that the quantity of AEA has a greater influence on pore structure, and additionally the freeze-thaw action only slightly modifies the pore structure. As AEA increases, a progressive rise of the porosity and the number of pores is observed up to a maximum value. Next, a decrease is noticed. Moreover, there is not a linear relation between porosity and AEA. Furthermore, as AEA increases, a variation of its size and shape is observed. Alternatively, the effect of freeze-thaw cycles is more complex and does not show a monotonous tendency. The results reveal that the first 50 freeze-thaw cycles have the strongest influence on pore structure, observing a decrease in porosity. For the rest of the cycles, the porosity increases progressively resulting, after 300 freeze-thaw cycles, in a slightly lower porosity in almost all series than in those presented at the beginning. Hydration of unhydrated cement particles alongside with microcracking act as opposite performances during the freeze-thaw cycles. Therefore, this can suggest that, under these conditions, freeze-thaw action is not able to damage significantly the microstructure of concrete. The results show that the series with a lower AEA content show a better behavior under freeze-thaw cycles. In this case, the specimens exhibit a lower porosity and a higher level of small pores, and the pores evince a more elongated shape. All these features lead to a more impermeable concrete and, therefore, with a better performance under freeze-thaw cycles. The authors are grateful for the financial support from the Ministerio de Economía y Competitividad, PID2019-110928RB-C32, Spain. 2025-01-29T12:40:13Z 2025-01-29T12:40:13Z 2021-12 info:eu-repo/semantics/article info:eu-repo/semantics/acceptedVersion 0165-232X http://hdl.handle.net/10259/10073 10.1016/j.coldregions.2021.103397 eng Cold Regions Science and Technology. 2021, V. 192, 103397 https://doi.org/10.1016/j.coldregions.2021.103397 info:eu-repo/grantAgreement/AEI/Plan Estatal de Investigación Científica y Técnica y de Innovación 2017-2020/PID2019-110928RB-C32/ES/DAÑO A FATIGA ALTERNA EN HORMIGON DE MUY ALTA RESISTENCIA A TRACCION REFORZADO CON FIBRAS. MAPEO Y CUANTIFICACION DEL DAÑO CON TOMOGRAFIA COMPUTERIZADA/ Attribution-NonCommercial-NoDerivatives 4.0 Internacional http://creativecommons.org/licenses/by-nc-nd/4.0/ info:eu-repo/semantics/openAccess application/pdf Elsevier https://riubu.ubu.es/bitstream/10259/10073/4/Gonzalez-crst_2021.pdf.jpg Hispana TEXT http://creativecommons.org/licenses/by-nc-nd/4.0/ RIUBU. Repositorio Institucional de la Universidad de Burgos http://hdl.handle.net/10259/10073