PSI - Issue 37

João Custódio et al. / Procedia Structural Integrity 37 (2022) 590–597 João Custódio et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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higher, then they are classified as Class III (aggregate or aggregate combination very likely to be alkali-reactive). In this case, it is necessary to adopt preventive measures, which are selected according to the methodology set in section §4.3.2 of LNEC Specification E 461 (LNEC, 2021b).

0.00 0.04 0.08 0.12 0.16 0.20 0.24 0.28 0.32 0.36 0.40 0.44 0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 60 64 68 72 76 80 Expansion (%) Time (weeks) AHS#1 AHS#2 AHS#3 BHS#1 BHS#2 BHS#3 CHS#1 CHS#2 DHS#1 DHS#2 DHS#3 EHS#1 EHS#2 FHS 0.00 0.04 0.08 0.12 0.16 0.20 0.24 0.28 0.32 0.36 0.40 0.44 0 91 182 273 364 455 546 637 728 819 910 1001 1092 1183 1274 1365 1456 1547 1638 1729 1820 Expansion (%) Time (days) AHS#1 AHS#2 AHS#3 BHS#1 BHS#2 BHS#3 CHS#1 CHS#2 DHS#1 DHS#2 DHS#3 EHS#1 EHS#2 FHS

(a)

(b) Fig. 1. (a) Results obtained in the RILEM AAR-4.1 test; (b) Results obtained in the RILEM AAR-3.1 test; (a) (b) The horizontal dashed lines represent the expansion limits defined in LNEC Specification E 461 (LNEC, 2021b). From the results obtained in the AAR-4.1 test (Fig. 1a), it was observed that at 13 weeks of testing only the hydroelectric scheme AHS exhibited an expansion lower or equal to the limit set in LNEC E 461 (0.02 %) (although, only two of the three aggregate batches tested; also please note that EHS was not assessed with this test method), and that at 20 weeks of testing only the aggregates from hydroelectric schemes AHS and FHS produced an expansion below or equal to the limit set in LNEC E 461 (0.03 %). Thus, according to LNEC Specification E 461, the aggregates of hydroelectric schemes AHS (two of the three batches assessed) and FHS are classified as Class II (potentially alkali reactive or alkali-reactivity uncertain), and the aggregates from the remaining hydroelectric schemes must be assessed by the CPT. In terms of the potential alkali-reactivity determined with this test method, the aggregates tested can be ordered, in terms of increasing reactivity, like follows: FHS < AHS < DHS < CHS < BHS. Looking now into the AAR-3.1 test results (Fig. 1b), it can be seen that at 12 months of testing only the hydroelectric schemes EHS and FHS exhibited an expansion equal or lower than the limit set in LNEC Specification E 461 (0.03 %), and that at 24 months only the aggregate from hydroelectric scheme FHS produced an expansion below the limit set in LNEC Specification E 461 (0.04 %). Hence, only the latter aggregate can be considered as Class II (potentially alkali-reactive or alkali-reactivity uncertain), all others are classified as Class III (aggregate or aggregate combination very likely to be alkali-reactive). In terms of the potential alkali-reactivity determined with this test method, the aggregate combinations tested can be ordered, in terms of increasing reactivity, like follows: FHS < EHS < AHS < DHS < CHS < BHS; thus, a behaviour similar to that obtained with the previous test method.