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

592

3

3. Tests and analysis The test campaign devised to assess the alkali-silica potential reactivity of the aggregates included petrographic examination, scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDX), chemical analysis, and expansion tests carried out on concrete prisms produced with materials of the same provenance as those used in the dams’ construction. The global test campaign is summarized in Table 2. However, due to the limited length of this paper not all results of the study will be presented or discussed here.

Table 2. Global experimental testing campaign. Test / Analysis AHS

BHS

CHS

DHS

EHS

FHS

Petrographic examination

½

½

½

½

½

½

SEM/EDX













Alkali content

 ;  ; 

 ;  ; 

 ;  ; 

 ;  ; 

✓ ; ✓ ; 

✓ ; ✓ ; 

RILEM AAR-3.1 RILEM AAR-4.1

✓

✓

✓

✓





✓

✓

✓

✓

✓

✓

ASTM C1293 / RILEM AAR-3.1

✓

✓

✓

✓

✓



Aggregate type Fine: granitic Coarse: granitic NOTATION: ✓ – test completed; ½ – first stage of test completed;  – test will commence soon;  – test is ongoing;  – test will not be performed. Fine: granitic Coarse: granitic Fine: non-alkali reactive limestone Coarse: granitic

3.1. Petrographic examination and microstructural characterisation The petrographic examination is being performed according to LNEC Specification E 415 (LNEC, 2021a) and aims at characterizing the rock materials and identifying the presence of potentially alkali-reactive constituents. The examination will be complemented with a microstructural characterization of the concrete by scanning electron microscopy with energy-dispersive X-ray analysis, SEM/EDX. The SEM/EDX characterization will be made according to LNEC Specification E 402 (LNEC, 1993b). The chemical analysis, namely the determination of the aggregate s’ alkali content, is being made to verify if the aggregates under study are capable of supplying alkalis to the concrete pore solution, thus providing an indication of the eventual existence of an aggravating factor for ASR development in concrete. The analyses are being performed to according to LNEC Internal Method LABTEC MI 115 (LNEC, 2007b) and to the Portuguese standard NP 1382 (IPQ, 1976). 3.3. Expansion tests The assessment of the aggregate potential alkali reactivity is being carried out with the accelerated concrete prism test, ACPT, and the concrete prism test, CPT, respectively, according to the RILEM AAR-4.1 (RILEM, 2016e) and the RILEM AAR-3.1 (RILEM, 2016d) test methods. The effect of using fly ash to mitigate the deleterious development of ASR, was evaluated with ASTM C1293 (ASTM, 2008) standard test method and with ASTM C1293 and RILEM AAR-3.1 modified tests methods. The modification in the former method consisted of assessing at the same time both fine and coarse job aggregates and, in the latter, adapting it to the use of fly ash, using the same principle as that defined in ASTM C1293. 3.2. Chemical analysis