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Equivalent functional unit in recycled aggregate concrete 309

1.45
1.4
1.35 delta c = 0.010 m
1.3
h RAC /h RC 1.25 delta c = 0.015 m
delta c = 0.020 m
1.2
delta c = 0.025 m
1.15
1.1
1.05
1
–8.000 –6.000 –4.000 –2.000 0.000 2.000
α 5
Figure 11.7 h RAC /h NAC in function of α 5 (slabs).

11.6.4 K as a function of cracking SLS
The definition of an EFU in RAC as a function of α 5 only is not feasible because this
ratio depends on α 2 and α 6 . The parametric study on slabs (Dobbelaere et al., 2016)
was made using different load combinations and different rebar covers, ranging from
1.0 to 2.5 cm, with increments of 0.5 cm. Parameters α 2 and α 6 were also used within
the estimated upper and lower values, according to the literature review.
Fig. 11.7 shows that most of the parametric studied cases produced a negative
α 5 parameter, which is unreasonable for practical purposes. Considering only the
cases that fall within α 1 95%-certainty limits, few results remain and, generally
speaking, these will have higher equivalent units for other limit states.
Consequently, it can be stated that the cracking SLS does not correspond to a con-
ditioning situation for current RAC structures.

11.6.5 Multi-criteria analysis
For each limit state, with the exception of the cracking SLS, it was possible to
establish an EFU in RAC. Some cases were excluded, due to being unreasonable
for practical purposes. The EFU in RAC for slabs is the most conditioning of the
various parameters previously computed [Eq. (11.10)].

( )
α 1 α 3 α 4 α 6 =α 2
h RAC h RAC h RAC h RAC h RAC
K 5 5 max ; ; ; (11.10)
h NAC h NAC h NAC h NAC h NAC

11.7 Application to slabs and validation of the method:
case studies

The multi-criteria analysis used to determine the EFU proposed by Dobbelaere
et al. (2016) was tested for several RAC gathered during the literature review. For