1 Scope of application This standard is used to determine the moisture content of all types of soil except gypsum soil and organic soil (with soil containing more than 20% organic matter).
2 Principles of measurement The weight loss of a soil sample when baked at 105 °C to constant weight is the quality of the moisture content of the soil sample.
3 Instruments and Equipment
3.1 Earth drilling;
3.2 soil sieve: pore size 1mm;
3.3 aluminum box: small diameter of about 40mm, height of about 20mm;
Large diameter of about 55mm, height of about 28mm;
3.4 analytical balance: the amount of sense is 0.001g and 0.01g;
3.5 small electric constant temperature oven;
3.6 Dryer: Within the discoloration of silica gel or anhydrous calcium chloride.
4 sample selection and preparation
4.1 Air-dried soil samples: Select representative samples of air-dried soil, crushed, passed through a 1mm sieve, and mixed until ready for use.
4.2 Fresh soil samples: Take a representative sample of fresh soil in the field, and scrape off the upper floating soil in the soil drill. About 20 g of soil at the required depth in the middle of the soil drill will be quickly packed into the known accurate mass. The large aluminum box is tightly closed, packed in a wooden box or other container, brought back into the room, and the outer surface of the aluminum box is wiped clean, immediately weighed, and the moisture is measured as soon as possible.
5 Measurement procedure
5.1 Determination of moisture content in air-dried soil sample Take a small aluminum box and bake it in a thermostatic chamber at 105°C for about 2 hours. Transfer it to a desiccator and cool it to room temperature. Weigh it to the nearest 0.001g. The dried soil sample was well-mixed with a corner scoop, and about 5 g was dipped, evenly spread in an aluminum box, covered, and weighed to the nearest 0.001 g. The aluminum lid was peeled off, placed under the box, and baked in an oven preheated to 105°C for 6 hours. Take out, cover it, move it into a desiccator and cool to room temperature (approximately 20 minutes). Weigh it immediately. The determination of moisture in air-dried soil samples should be performed in two parallel assays.
5.2 Determination of Moisture in Fresh Soil Samples Large aluminum boxes containing fresh soil samples are weighed on an analytical balance to the nearest 0.01g. Uncover the lid, place it under the box, and bake it in a baking oven that has been preheated to 105°C for 12 hours. Remove, cover, cool to room temperature in a desiccator (approximately 30 minutes) and immediately weigh. Determination of fresh soil moisture should be measured in triplicate.
Note: Once weighed after baking for a specified time, it will reach “constant weightâ€.
6 Calculation of measurement results
6.1 Calculation Formula Moisture (analytical basis), %=[(m1-m2)/(m1-m0)]?00....................................(1)
Moisture (dry basis), %=[(m1-m2)/(m2-m0)]?00....................................(2)
In the formula: m0── dry aluminum box quality, g;
m1─Aluminum box and soil quality before drying, g;
m2─Aluminum box and soil quality after drying, g.
6.2 The results of the parallel determination are expressed as an arithmetic average, leaving one decimal place.
6.3 The difference between the results of the parallel determination shall be no more than 0.2% for air-dried soil samples with moisture less than 5%, no more than 0.3% for wet soil samples with 5-25% moisture content, and large-grained particles (particle size: approximately 10mm) with heavy moisture for moisture greater than 15%. Soil samples should not exceed 0.7% (equivalent to a relative difference of no more than 5%).
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