Page 305 - New Trends in Eco efficient and Recycled Concrete

268 New Trends in Eco-efficient and Recycled Concrete

Table 10.3 Partial factors for design values of actions and materials
Design situations Partial factors for loads Partial factors for
materials
Permanent Variable Concrete Steel

ULS a 1.35 1.5; (ψ 0 1.5) c 1.5 1.15
Persistent and transient
SLS b 1.0 1.0; (ψ 2 1.0) d 1.0 1.0
Quasi-permanent
a
Ultimate limit states.
b
Serviceability limit states.
c
ψ 0 5 0.7 (dwellings).
d
ψ 2 5 0.3 (dwellings).
NAC was not less than approximately 30 MPa, because the Eurocode 2 Part 1
requirement for minimum concrete in XC3 XC is C30/37. Specific proportions of
mixes were not important since the amount of reference flows in all cases was cal-
culated to deliver the same function of the structure.
Based on the aforementioned two criteria, two experimental campaigns were
selected: an experimental study on microstructure and structural behaviour of RAC,
a doctoral thesis by Etxeberria (2004) at Universitat Polite `cnica de Catalunya; and
the study on the shear capacity of RC beams made with recycled aggregate by Han
et al. (2001). In the former investigation, RCA water absorption after 24 h was
4.45% while in the later it was 5.73%. There were two other tests in the database
that employed RCA with higher absorption (about 6%): Sato et al. (2007) and
Knaack and Kurama (2014), but they were disregarded either for different ages at
which strength of compared concretes were tested or for very untypical obtained
results in the latter case. Mix proportions and measured compressive strengths of
selected concrete mixes are presented in Table 10.4, where designation 1 refers to
RAC with ‘high’ quality RCA and companion NAC, while designation 2 refers to
RAC with ‘low’ quality RCA and companion NAC. Based on the measured com-
pressive strengths f cm , all concrete properties needed in design were calculated
according to Eurocode 2 Part 1 provisions, or, where it was not possible for
RAC, according to selected proposals published in literature.
Medium ductility S500 B (grade 500 class B) reinforcing steel has been adopted.

10.4.1.3 Structural analysis and design of RC floor slab
Structural analysis was performed with finite element-based software TOWER 7
(Radimpex Software, 2012).
Design criteria for both concrete mixes NAC and RAC were adopted according
to Eurocode 2 Part 1 and EN 1992-1-2 (CEN/TC250, 2004b). In the following,
EN 1992-1-2 is referred to as Eurocode 2 Part 2.