Civil Engineering Reference
In-Depth Information
15
800
14
700
13
12
600
11
500
10
400
9
W/B = 0.28
W/B = 0.32
W/B = 0.36
8
300
7
200
6
5
100
4
0
0
5
10
15
20
25
30
Recycled LCD glass content (%)
11.2
V-funnel time and slump flow of fresh self-consolidating
concrete with different recycled LCD glass content. W/B = water/
binder ratio. Adapted from Wang and Huang (2010a).
11.2.2 Air content and fresh unit weight
Compared with conventional concrete, fresh recycled glass concrete has a
lower air content. There is a tendency that the air content decreases with
the increase in glass content. This tendency can be attributed to the poor
geometry and the smooth surface of recycled glass, which helps decrease
porosity between recycled glass and cement paste.
In general, glass has a lower density than natural sand. As a result, unit
weight of fresh recycled glass concrete is reduced as the glass aggregate content
is increased with various water to binder ratios, though the incorporation of
glass may decrease the air content (Topcu and Canbaz, 2004; Ismail and Al-
hashmi, 2009). Likewise, the use of recycled glass powder as a replacement
of cement can also reduce the fresh concrete unit weight, as the density of
glass is lower than that of cement.
11.2.3 Setting time
As discussed in Section 11.2.1, the presence of glass particles increases
the efficient water content in the concrete mixture due to hydrophobic and
lower water absorption of glass. As a result, concrete with recycled glass
exhibits both prolonged initial and final setting times. Figure 11.3 indicates
