PSI - Issue 54

João Custódio et al. / Procedia Structural Integrity 54 (2024) 271–278 João Custódio et al. / Structural Integrity Procedia 00 (2023) 000 – 000

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3.5. Results and discussion The results from the relative humidity (R.H.) and temperature (T.) measurements, made between February 2019 and July 2022 on Pier P8, are presented in Table 2.

Table 2. Results obtained from the relative humidity and temperature measurements made between February 2019 and July 2022.

Location

L1-5

L1-15

L2-5

L2-15

L3-5

L3-15

L4-5

L4-15

L5-5

L5-15

Date

R.H. (%)

T. (ºC)

R.H. (%)

T. (ºC)

R.H. (%)

T. (ºC)

R.H. (%)

T. (ºC)

R.H. (%)

T. (ºC)

R.H. (%)

T. (ºC)

R.H. (%)

T. (ºC)

R.H. (%)

T. (ºC)

R.H. (%)

T. (ºC)

R.H. (%)

T. (ºC)

2019/02/07-08 88.9 10.1 87.1 11.4 79.5 9.8 80.9 9.8 94.1 8.1 97.9 8.2 92.4 9.8 99.5 10.1 88.8 14.7 94.7 13.7 2020/07/20-21 87.0 30.5 86.8 30.7 77.0 28.7 87.0 28.8 100 26.3 96.6 26.4 98.7 35.2 97.8 35.7 95.2 28.5 100 29.0 2020/11/05-07 84.0 15.2 99.1 14.2 73.8 16.8 97.0 15.8 100 14.0 100 13.2 100 15.1 100 15.7 96.4 15.5 100 15.5 2021/05/10-12 79.6 19.6 82.2 17.4 79.6 19.6 82.2 17.4 100 14.5 97.1 14.5 98.9 17.5 100 18.1 100 17.5 100 18.0 2022/02/07-09 - - - - 63.8 28.2 62.8 28.0 94.8 7.3 92.2 7.1 100 14.1 99.8 12.5 92.8 11.2 100 11.4 2022/06/30-07/01 - - - - 72.4 19.4 82.4 19.5 92.8 19.0 95.7 19.2 90.5 24.8 87.6 26.1 92.4 20.3 98.1 21.1 Average 85 19 89 18 74 20 82 20 97 15 97 15 97 19 97 20 94 18 99 18 Notation: L1-5, L1-15 – starting of the column of the pier P8, exterior north surface, measurement at depth of 5 cm and 15 cm, respectively; L2-5, L2-15 – starting of the column of the pier P8, exterior south surface, measurement at depth of 5 cm and 15 cm, respectively; L3-5, L3-15 – starting of the column of the pier P8, interior north surface, measurement at depth of 5 cm and 15 cm, respectively; L4-5, L4-15 – footing of the column of the pier P8, south side surface, measurement at depth of 5 cm and 15 cm, respectively; L5-5, L5-15 – footing of the column of the pier P8, south top surface, measurement at depth of 5 cm and 15 cm, respectively; R.H. – relative humidity; T. – temperature. The overall arithmetic mean values of R.H. and T. registered in the column (L1, L2 and L3) and footing (L4 and L5) of pier P8, in the period 2019-2021, were, respectively, 89 % and 18 ºC, and 98 % and 19 ºC. In terms of ASR, both values of R.H. are considered sufficient to sustain its development; the latter value of R.H. would allow, in addition to ASR, the development of DEF. Nevertheless, it should be noted that in the periods during in which the R.H. is higher than those values, both ASR and DEF will progress at higher rates. The higher humidity level observed in the footing’s concrete may have led to a higher develop ment of the swelling reactions; this is supported by the fact that the footing exhibits more severe cracking than the column. The arithmetic mean values of R.H. and T. registered, in the period 2019-2021, at locations L1 (exterior, north), L2 (exterior, south) and L3 (interior, north), in the column, were, respectively, 87 % and 19 ºC, 82 % and 18 ºC, and 98 % and 16 ºC; whilst in the footing (L4 and L5) were, respectively, 98 % and 20 ºC, and 97 % and 19 ºC. Higher R.H. and similar T. mean values were observed for the surface directed to north, in comparison with that facing south. The R.H. mean value was higher at L3 than at L1, which was not expected; the T. mean value was lower at L3 than at L1. The visual evidence at L3 suggest that the water collected at the bridge deck may be entering the inner volume of the column and running down the north face of column and, consequently, over location L3; thus, explaining the observed trend. The R.H. mean values are higher in the footing (L4 and L5) than in the column (L2), this might be explained by the fact that the footing occasionally contacts directly with water from the river and receives all the water that runs down the column, and also because the footing is more cracked than the column. The arithmetic mean values of R.H. and T. registered, in the period 2019-2021, at 5 cm and 15 cm in the column, were, respectively, 87 % and 18 ºC, and 91 % and 17 ºC; whilst in the footing were, respectively, 96 % and 19 ºC, and 99 % and 19 ºC. Hence, a slight increase in R.H. with the depth of the reading is it readily observable; consequently, it is expected that the concrete in the core of the assessed elements will exhibit an even higher level of moisture. The difference in percentage for the R.H. mean values with depth was +5 % for L1, +12 % for L2, -1 % for L3, +2 % for L4 and +4 % for L5. Thus, for the column, a higher difference in R.H. mean values at 5 cm and 15 cm was obtained for the exterior south surface (L2), in respect to that of the exterior north surface (L1), this might be due to the higher solar incidence in the exterior south surface. In the case of the footing, this difference was only slightly lower for the location closest to the ground (L5), in comparison to that of the top (L4). In terms of the north side of the column, a higher difference was recorded for the exterior surface (L1), than for the interior surface (L3). It should be mentioned that local L3 exhibits visual signs of receiving running water from the top of the column (in fact, on some visits to the site, water was found to be running down the wall).