Microwave-assisted accelerated curing of precast concrete - Microwave-Assisted Concrete Technology: Production, Demolition and Recycling - page 71

60

55

50 3 days

45

7 days

40

28 days

35

30

25

0 30 60

Curing Time (min)

90 120

Figure 2 . 21 Variation in the compressive strength of mortar specimens (w/c = 0.44) with
curing time at microwave power of 150 W. (From Wu, et al., Microwave cur-
ing technique in concrete manufacture. Cement and Concrete Research , 1987,
17 (2):205-210. With permission.)

60

50

40

30

20

3 days
7 days
28 days

10

0

0 30 60

Curing Time (min)

90

Figure 2.22 Variation in the compressive strength of mortar specimens (w/c = 0.44)
with curing time at a microwave power of 300 W. (From Wu, et al.,
Microwave curing technique in concrete manufacture. Cement and Concrete
Research , 1987, 17 (2):205-210. With permission.)

studies of microwave curing showed that, unlike steam curing, microwave
curing applied for optimal durations and at optimal power can be used
to increase both the early and 28-day strengths of mortar, cement paste,
and concrete [2,12]. Figures 2.21 and 2.22 show the 3-, 7-, and 28-day
compressive strengths of the mortar specimens cured with microwaves at
two different power levels [2]. The optimal duration of curing to achieve
both relatively higher early strength and 28-day strength can be identified