Civil Engineering Reference
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50
45
40
35
30
25
20
15
10
5
0
C1
C2
C3
C4
Microwave Power Variation Schemes
7-day microwave cured
4.5-hour microwave cured
7-day normal cured
Figure 2.32
Compressive strength of microwave-cured concrete specimens subjected
to various microwave power variation regimes. (From Leung, C.K.Y., and
Pheeraphan, T., Determination of optimal process for microwave cur-
ing of concrete.
Cement and Concrete Research
, 1997,
27
(3):463-472.
With permission.)
early and late strengths of regime C4 are lower than regime C2. While both
regimes (C2 and C4) reach relatively similar temperatures after curing, the
more rapid curing at early ages in C2 seems to be closer to the optimal pro-
cess. Compared to C2, C1 has higher early age strength but lower later age
strength. Moreover, the high heating rate of regime C3 results in consider-
able reduction in the later age strength of the concrete. By summing the
percentage of the reference strength achieved at 4.5 hours and 7 days, the
overall strength development pattern of C2 seems to be slightly better than
C1. In addition, from power-versus-time curves, it can be determined that
the total power consumption of C2 is about only 0.241 kWh, which is
considerably lower than that of C1 (0.309 kWh). This indicates that the
feedback-temperature control system can be used to achieve relatively simi-
lar early and later age strengths compared to the constant power regime
with about 20% lower energy consumption. Therefore, it can be concluded
that although the use of the feedback control system to regulate power
during the curing regime rather than microwave curing at constant power
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