Time necessary for microwave drying of mineral soils

Abstract

Construction of large earthworks (cuts and embankments) brings the necessity of fast and reliable testing quality control procedures to be applied directly on the building sites. The paper presents a conventional, standardized method for determining soil moisture - consisting in drying a sample in a machine that circulates dry, hot air. This procedure is widely used and is considered to be very reliable and effective for any type of soil. Its main disadvantage is the time it takes to complete, as it takes a minimum of 24 hours to obtain the results of moisture content and consequently, to compute the compaction (density) indicator. An experiment was conducted, based on former Jastrzębska’s experiments and recommendations, consisting in drying soil samples in a microwave oven. The results were confronted and discussed with a special regard to necessary for microwave drying of mineral soils of different nature. Some recommendations were given in conclusions. As all the authors are still students, some remarks were juxtaposed concerning the importance of practical “experience-based” education within a frame of international exchange programs.

The Impact of Microwave Drying on the Structure of Exemplary Soils—Insights Using X-ray Microtomography

“…In the case of non-cohesive soils, the results indicate that the appropriate MO drying procedure marginalizes the undesirable possible effects of rapid and intense heating. This conclusion has been supported by studies that have been conducted on a larger number of non-cohesive samples [ 6 , 7 ]. Furthermore, the greater the fraction of non-cohesive soil, the faster the drying can be performed, which is important and helpful in preparing samples several times from the same material, for example, direct shear tests.…”

“…Many experimental studies have explored rapid microwave drying [ 6 , 7 ] and the influence of multiple wet–dry cycles (such as those that occurred during laboratory drying) on the physical and mechanical properties of soil or its mixtures with various additives (e.g., with cement, liquid modifiers, bentonite, etc. ), which include thermally modified swelling parameters [ 8 , 9 ], hydraulic conductivity/permeability coefficients [ 8 , 10 , 11 ], shear strength [ 12 , 13 ], durability, stiffness, and the void ratio [ 12 ], Atterberg limits [ 8 ], and even intensification of landslides [ 11 , 14 , 15 ].…”