PSI - Issue 64

Said Debbakh et al. / Procedia Structural Integrity 64 (2024) 130–136 S. DEBBAKH and al. / Structural Integrity Procedia 00 (2024) 000 – 000

132

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(Benidir and al.,2023). The ordinary concrete used was C25/30 class, prepared using a traditional method, i.e. mixing with a manual shovel on a platform. The materials used were of Algerian origin (CEM II/A 42.5 cement from Lafarge Algeria cement factory, natural river sand with granular class 0/3, natural fine dune sand from Algerian Sahara with granular class 0/1 and crushed aggregate granular class 8/15 from the local quarry of Keddara. The constitutive components of the ordinary concrete mixture are listed in Table 1. Rebound hammer and pull-off tests were carried out on three different zones of each reinforced concrete columns, see Fig 1(b, d), (from upper to lower, zone 1, zone 2 and zone 3). The rebound hammer test was carried out on six locations according to NF EN 12504-2 specifications, see Fig. 1(b). Then, six dollies have been glued at the six locations according to NF EN 1542 specifications, a distance of 200 mm separates the two dollies from their axis, and 100 mm from the edge, see Fig 1(d). Thus, a total of 18 measurements were therefore taken on each reinforced concrete column at the red cross point, Fig. 1(a).

Table 1. Ordinary concrete mixture for 1 m 3 and slump test results (Benidir and al., 2023). Components Unit Proportions Cement 350

Natural river sand

464 271

kg/m 3

Natural fine dune sand

Aggregates

1058

Water

210

S 2 (Slump test: 50 - 90 mm)

Consistency class

mm

c

b

d

Pull-off test

a

200 mm

100

100

Fig. 1. (a) Delimitation of zones testing (Benidir, Debbakh, et al. 2023), (b) Rebound Hammer test, (c) Incision location test, (d) pull-off test.

3. Non-destructive and partially destructive evaluation methods 3.1. Rebound Hammer test

To assess the compressive strength of the two reinforced concrete columns, the N-type Schmidt Hammer test according to the (NF EN 12504-2, 2021) was used. The appropriate compressive strength values were derived from the rebound number measurement, using the manufacturer’s table. Before testing, the rebound Hammer was calibrated on steel reference anvil, with an impact area having a hardness of at least 52 HRC (Hardness Rockwell C) according to the (EN ISO 6508-1, 2016). The Schmidt Hammer test was carried out perpendicularly to the façades of the reinforced concrete columns, Fig. 1(b). 3.2. Pull-off test On each point of rebound number measurement, the pull-off test was carried out. The pull-off equipment has a pulling capacity of 16 kN, complying with (Standard NF EN ISO 4624), sufficient to cause tensile bond failure of