But high strength lightweight aggregate concrete for structural
uses had been prepared (Samuel et al., August 2011) by using a
vacuum saturated pumice to serve as both the fine and coarse aggregates,
with the w/c controlled between 0.21 and 0.25. The re-
sults showed that this type of lightweight aggregate concrete was
able to achieve a 28 d compressive strength between 36.5 MPa and
40.5 MPa, while the f
/D ratio tested at 28 d curing age was ranged
from 18.1 to 19.6. Kockal and Ozturan (2011) investigated the mechanical
properties of structural lightweight aggregate concrete by
using two different types of sintered lightweight fly ash aggregates
and one type of cold-bonded lightweight fly ash aggregate, the
c
B. Zhang, C.S. Poon / Journal of Cleaner Production 99 (2015) 94e100 95
results showed that adding 10% silica fume by cement weight waseffective in improving the mechanical and durability properties of
the concrete. Oil palm shell (OPS) is another lightweight aggregate
(density 1190 kg/m
3
, 24 h water absorption 21.82%) that can replace
natural coarse aggregate for the production of lightweight aggregate
concrete, and it was demonstrated that when the cement
content was controlled at 550 kg/m
3
and the w/c at 0.425, the f
/D
ratio from 22.1 to 24.3 was achieved at 28 days curing age (Shafigh
et al., 2011).