Projects

Background

The microwave measurement technology has been increasingly used in industry to measure some material properties (e.g. moisture content, concentration, density and so forth) during ongoing manufacturing, which includes on conveyor belts, in chutes, etc. This is a non-destructive and real-time monitoring technique that measures the entire cross-section of the material in static and dynamic conditions during material production. Microwaves can travel through non-conductive materials, and during transmission, the intensity of the microwave arriving at the receiver decreases with increasing moisture in the material being analysed (see Fig. 1 for a graphical illustration). Microwave technology can measure the dielectric properties of a material in two main ways: (1) by reflection and (2) by transmission. The dielectric properties of a material are directly correlated with its bulk density and moisture content. However, the dielectric properties of a material can also be influenced by temperature and other physical properties of the material, such as particle size distribution of UGMs.

Project Objectives

1. To conduct a comprehensive literature study on microwave drying and microwave moisture sensing techniques for conditioning unbound pavement materials

2. To develop a suitable laboratory testing protocol to study the use of microwave drying technique for obtaining targeted uniform moisture content in unbound granular materials (UGMs)

3. To investigate the influence of microwave drying on physical and index properties of UGMs

4. To examine the application of microwave moisture sensing technique for non-destructive and real-time measurement of moisture content in UGMs

5. To characterise the key factors affecting both microwave drying and microwave moisture measurement in UGMs

6. To develop practical guidelines for the implementation of microwave technology in quarries for quality assurance (QA) of UGMs