Civil Engineering Reference
In-Depth Information
Table 4.9 Compressive strength behaviour of concrete after wetting and drying cycle
Concrete type
Compressive strength (MPa)
Strength loss (%)
Appearance
Before ageing
After freezing- thawing
Manso et al. (
2006
)
Control
38.5
27.3
29
Good
EAF-slag-1
33.7
19.9
41
Slight damage
EAF-slag-2
35.3
24.7
30
Good
EAF-slag-3
30.2
16.6
45
Slight damage
EAF-slag-4
30.7
15.6
49
One sample cracked
Pellegrino and Gaddo (
2009
)
Control
30.4
28.7
5.60
EAF-slag
44.4
32.7
26.52
25 C to complete one thermal cycle. However, a reduction in pulse velocity and
an increase in water absorption after the completion of thermal cycles indicated
better performance of concrete with steel slag aggregates than of the limestone
aggregates concrete due to the denser microstructure of the former concrete
compared with the latter.
4.3.3.5 Other Durability Behaviour
Manso et al. (
2006
) investigated the alkali-aggregate reaction of EAF-slag to be
used as aggregates in concrete by using the ASTM C1260 method. According to
the authors, slag contains a significant amount of glassy phase, which can react
with alkalis present in cement. The average value of expansion was 0.14 % after
16 days and 0.15 % after 28 days, both well below the specified value of 0.2 %.
However, the presence of free CaO and MgO in EAF-slag overestimate the
expansion value.
Maslehuddin et al. (
2003
) detected a better performance in concrete with steel
slag aggregates than in limestone concrete when both were subjected to chloride
induced corrosion. The time to initiation of reinforcement corrosion and time to
cracking of concrete specimens were, respectively, 190 and 517 h for conventional
concrete and 198-367 h and 509-774 h for steel slag aggregates concrete. This
was mainly due to a denser microstructure in steel slag aggregates concrete than in
NA concrete. Lower water absorption capacity and higher ultrasonic pulse velocity
in concrete with steel slag aggregates than in NA concrete were also observed.
4.4 Blast Furnace Slag
The use of BFS as aggregates in concrete is not as common as its use as a
component in cement. However, some recent reports indicate that this material
(particularly air-cooled BFS) can be used as an aggregate in concrete preparation.
