On the possibility of concrete destruction under high-power microwaves generated by e-beam

Abstract

A potential cleaning method for polluted construction surfaces by high-power pulses of microwave radiation may be based on the destruction of a surface thin layer by the action of shock waves generated due to dissipation of microwave energy. When defining the possibility of concrete plane layer destruction by a high-power microwave radiation flux it should be stressed that dry concrete (being a dielectric material) conducts electromagnetic radiation rather well (specific resistance is more than 10/sup 3/ Ohm.m), but shock wave generation and fragment formation under its action occurs most intensively for local energy release. The main prime problem is to create a small region in a material capable under microwave pulses to generate a shock wave which has the ability to cause fragmentation on a sample surface. Such a region should have increased conductivity which ensures the creation of the region with high energy density. The creation of such a region can be available, for example, by saturation of the concrete surface with a conductive salt solution, as it is known that concrete has a water absorption from 4-8% up to 30-40% of its mass. Current experiments show that the specific resistance of a concrete region is equal to 50 Ohm. m, and the skin length, corresponding to 4 mm wavelength electromagnetic radiation, is 1.2 cm.