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Equivalent functional unit in recycled aggregate concrete 305

Table 11.2 Ratios for each performance property
Ratio Meaning

α 1 5 f cm;RAC =f cm;RC α 1 expresses the relationship between the
average values of the compressive
strengths of RAC and NAC
α 2 5 E cm;RAC =E cm;RC α 2 is the ratio between the moduli of elasticity
α 3 5 K c;RAC =K c;RC α 3 is the ratio between the carbonation
coefficients
α 4 5 p ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi α 4 is the ratio between the chlorides diffusion
D RAC =D RC
coefficients
α 5 is the ratio between the average
α 5 5 f ctm;RAC =f ctm;RC
tensile strengths
α 6 5 ðϕ N; t 0 Þ RAC 1 1Þ=ðϕ N; t 0 Þ RC 1 1Þ α 6 is the ratio between the creep coefficients
ð
ð
plus 1
11.5.2 Limit states

11.5.2.1 Durability
Durability is affected by the fundamental parameters related to ratios α 3 and α 4 .
The literature review indicates that carbonation is more affected by the presence of
RAC than chloride penetration, yet the later effect is more life-limiting to rein-
forced concrete structures. To consider both these ratios, the design concrete cover
needs to be adjusted, assuming as starting cover the values defined in Eurocode 2,
for a given environmental exposure class, defined in clause 4.2(3).

11.5.2.2 Deformation serviceability limit state
Deformation SLS depends on the fundamental parameters α 2 and α 6 , for quasi-
permanent load combinations. Long-term deflection (a N Þ will need to respect the
standard defined values, and the compliance of deflection was conducted so that
a N;RAC # a N;NAC , even if that requires a change of h RAC .

11.5.2.3 Bending ultimate limit state

The verification of bending ULS is affected by fundamental parameter α 1 . As seen
in the previous section, for pure bending there is an equilibrium of tension and
compression forces, which allows the computation of the reinforcement ratios.
Assuming there is no change in reinforcement, the bending ULS compliance is
made by adjusting h RAC and correcting the corresponding load combination, due to
the higher dead load, as seen in Eq. (11.7).

p Ed;RAC
M Ed;RAC $ UM Ed;NAC (11.7)
p Ed;NAC