Civil Engineering Reference
In-Depth Information
Frondistou-Yannas (
1977
) observed lower aggregate to mortar bond strength
for RCAC than for conventional concrete. The ranking of bond strength versus
type of coarse aggregate can be arranged as: new granite (56 ± 15 lb) [ recycled
granite from demolished concrete (49 ± 18 lb) [ RCA (39 ± 14 lb) [ recycled
mortar (3139 ± 8 lb).
Razaqpur et al. (
2010
) determined the bond performance of conventional
concrete and concrete with RCA as the only coarse aggregate prepared by the
normal and the EMV methods according to the ASTM A944.99-2003 procedure.
They observed lower bond strength in RCAC prepared by the normal method. On
the other hand, the bond strength of RCAC prepared by the EMV method was
similar or even better than that of conventional concrete. However, they did not
observe any effect of aggregate type on the bond performance of the RCAC.
Gonzalez-Fonteboa and Martinez-Abella (
2005
) observed poorer fatigue per-
formance of RCAC than that of conventional concrete. Concrete fatigue was
evaluated via an indirect test where the compressive strength of cylindrical
specimens was determined using two loading rates: standard loading rate of
8.66 kN/s and one at 0.06 kN/s. They observed higher strength losses (9.03 %)
and therefore poorer fatigue performance for RCAC than for conventional con-
crete (4.77 %).
In the Xiao and Falkner (
2007
) study, the shape of the load versus slip curve
between RCAC and steel rebars was comparable to that observed for NAC and
steel rebars. They also observed a 12 and 6 % reduction in bond strength between
RCAC and steel rebars as compared to the strength observed for NAC and steel
rebars when 50 and 100 % of NA was replaced by RCA (Fig.
5.54
). On the other
hand, for deformed rebars, the bond strength was similar for all types of concrete
irrespective of the replacement level of coarse NA by RCA. For equivalent CS of
NAC and RCAC, they observed higher bond strength between RCAC with 100 %
RCA than between NAC and steel rebars.
Fig. 5.54 Bond strength
between concrete and steel
rebars for various types of
concrete (Xiao and Falkner
2007
)
