Concrete Strength Determination via S-Band Operating Microstrip Patch Sensing Antenna

Compressive strength of concrete is very important to provide good quality of concrete, ensuring public safety and increase the lifespan of concrete. One of the most important parameters influencing the concrete strength is moisture content. This paper proposed a portable microwave non-destructive method by designing a microwave patch antenna using Computer Simulation Technology (CST) to determine the moisture content of concrete. Two experimental studies are conducted where concrete cubes with various moisture content and concrete cubes cured for 28 days are prepared as testing materials. The microstrip patch antenna is connected to vector network analyzer via coaxial cable to obtain the reflection coefficient. The reflection coefficient is correlated with moisture content, which then related to the compressive strength of concrete cubes. Two equations are obtained from the relationship between reflection coefficient with moisture content and compressive strength. The equations show great potential of the microwave method in determination of moisture content and compressive strength of concrete cubes. The accuracy of predicting the moisture content and compressive strength is 93.37% and 97.43% respectively.