Microwave-assisted selective demolition of concrete - Microwave-Assisted Concrete Technology: Production, Demolition and Recycling - page 122

Drenching of concrete can be used to improve the eciency of removal based on
the site constraints.
Concrete dielectric properties are determined using an inbuilt or separate dielectric
measurement kit.
e desired removal depth and rate is determined based on the site requirements.
Concrete compressive and tensile strengths are determined using available structural
records or nondestructive tests.
Computer processor uses the information available on the dielectric properties of
concrete, mechanical properties of concrete and applicator conguration to estimate
the required microwave power, heating duration, and microwave frequency to achieve
the desired removal rate and depth.
Figure 3.36 Proposed framework for selection of appropriate microwave frequency,
microwave power, and heating duration.
methods. Such information should then be stored in the control system using
the user interface. It must be noted that drenching of the selected zones of
the concrete component with water may not always be possible because of
site restrictions and leakage of water. Second, an inbuilt dielectric measure-
ment kit or network analyser can be used to estimate the dielectric proper-
ties of the concrete. Third, the processor unit of the control system makes
use of the estimated dielectric properties, mechanical properties, applicator
configuration information, and other required data imported from the vari-
ous databases to estimate the required microwave frequency, microwave
power, and heating duration to achieve thermal stress and pore pressure
levels sufficient to exceed the compressive or tensile strengths of the con-
crete, respectively. The procedure used by the control system mentioned is
described in detail in Chapter 5.
3.7 MICROWAVE-ASSISTED DRILLING OF CONCRETE
One variation of the microwave-assisted selective demolition method is the
microwave-assisted drilling method for concrete. Drilling into concrete is an
inevitable part of most construction projects. Currently, mechanical drills
drill holes of different sizes in concrete; these holes can be used for install-
ing utility wiring and piping, attaching various equipment and supporting