Microwave Heating for Concrete Demolition

This study investigates microwave heating (MH) as a novel method for concrete demolition. MH offers a quieter, cleaner, and more efficient alternative to traditional concrete demolition techniques. Experimental tests were conducted using concrete cylinders of varying sizes (Ø2×4 in., Ø3×6 in., Ø4×8 in., and Ø6×6 in.), water-to-cement (w/c) ratios (0.36, 0.43, 0.50), and moisture conditions (saturated surface dry and oven dry). Specimens were exposed to three microwave powers (300 W, 600 W, and 1000 W) for durations between 2 to 6 minutes. The temperature of specimens was monitored using embedded thermocouples and a thermal camera. Results show that heating rate decreases with increasing specimen volume and w/c ratio, while higher microwave power provides faster temperature rise. For dry concrete, microwave penetration exceeds 8 in., compared to 4 in. in saturated concrete. Using numerical methods and statistical techniques provides a foundation for predicting temperature with a novel model equation. Additionally, the effect of microwave heating on compressive strength and bond between concrete and reinforcement rebar was evaluated, showing noticeable reductions in compressive strength and bond after MH. These findings highlight that microwave heating has the potential to demolish various types of concrete, including reinforced structures.