2026-04-17T20:35:20Zhttps://riubu.ubu.es/oai/request

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

00925njm 22002777a 4500 dc González Cabrera, Dorys Carmen author Mena Alonso, Álvaro author Mínguez Algarra, Jesús author Vicente Cabrera, Miguel Ángel author 2021-12 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. 0165-232X http://hdl.handle.net/10259/10073 10.1016/j.coldregions.2021.103397 Computed tomography Air-entraining agent Freeze-thaw cycles High-strength concrete Pore structure Pore distribution Influence of air-entraining agent and freeze-thaw action on pore structure in high-strength concrete by using CT-Scan technology