Investigation into the effects of microwave drying soil

Soil moisture content has various applications within the planning, construction and agricultural industries. It is of particular importance in geotechnical engineering testing and applications as the compaction characteristics and engineering properties of the soil are greatly influenced by the moisture content. One widely accepted method that is used to determine soil moisture content is the Oven Drying Method, this method is often used in engineering testing and applications due to its reliability. However, one of the major disadvantages of this method is the time required for heating. Microwave oven technology not only has the potential to increase the efficiency and time of heating but can assist in reducing the energy and cost of running the heating processes. This dissertation focuses on the effects that microwave oven heating has on the moisture content of soil and aims to optimise the effects of microwave drying to improve the reliability of the process for application within the industry. More than 160 samples were tested and more than 3000 thermal images were recorded in tests that looked at the effects of size, shape and moisture content in relation on the heating process in a microwave. From the tests conducted results have shown that: - Most samples experience significant loss of moisture in the first 2-6 minutes within the microwave - Sample size has minimal effect on the initial rate of change in a sample, rather it affects the commencement of the final drying stage and the time taken to microwave a sample. - Five minutes is an acceptable timeframe for placing 100g samples in a 1100W microwave before monitoring further mass change - Cubic polynomial functions can be used to identify trends and predict the optimum testing time of a specific soil. - To prevent clay samples from breaking or exploding during microwave testing, it is recommended that samples are prepared carefully, avoid using angular shaped samples/containers or to use a lower power output when conducting test for example 700W, which has been found suitable in preventing failure. - Moisture content affects the initial rate of change in mass of soil samples tested within a microwave - The implementation of microwave testing for a small soil testing business will allow for at least a 7% annual saving. With significant savings in electricity costs when implementing the microwave testing method into a business. It is recommended that microwave heating used solely or in combination with oven heating, be considered for moisture content testing within the industry in cost efficiency