T0170 -- 2007 Liquid limiting disc type instrument

Purpose and scope of application

The purpose of this test is to determine the liquid limit of soil according to the dish liquid limit method, which is suitable for soil with particle size less than 0.5mm and organic matter content less than 5% of the total mass of the sample.

2 Instruments and Equipment

2.1 TD170-1 manual liquid limit disc type instrument

TD170-2 electric liquid disc limiting instrument

2.2 TDTP202 electronic balance: weighing 200g, dividing value 0.01g.

2.3TD101 series oven

2.4 Others: drying cylinder, aluminum box, soil adjusting knife, sieve (hole 0,5mm), etc.

3 Test Procedure

3.1 Take about 100g of soil samples (soil samples with natural moisture content or air-dried soil samples) through a 0.5mm sieve, put them in a soil mixing dish, add pure water as needed, and mix them repeatedly with a soil mixing knife.

3.2 Take a part of the sample and lay it on the front half of the soil dish, as shown in Figure T 0170-1a). When laying soil, bubbles should be prevented from mixing in the sample. Trim the surface of the sample with a soil adjusting knife so that the thickest part is 10mm, and put the excess sample back into the soil dish. With the cochlear wheel as the center, delimit the sample into two halves with clear slots from the back to the center of the front soil dish with a delimiter (FIG. T 0170-2a). In order to avoid tearing of the seam edges or sliding of the sample in the soil dish, allow several more strokes from front to back and then from back to front to deepen the groove gradually, instead of one stroke, the last stroke from back to front will clearly touch the bottom of the dish. However, the number of grooves should be minimized.

3.3 Rotate the handle F at a rate of 2 turns per second to make the earth dish rise and fall repeatedly and hit the base G. Count the number of hits until the closing length of both sides of the sample at the bottom of the tank is 13mm. Record the number of hits, and take about 10g of the sample on both sides of the tank to determine its moisture content.

3.4 Transfer the remaining sample in the clay dish to the clay dish, add water and mix thoroughly and evenly, and conduct at least two more tests according to the provisions of 3.1 ~ 3.3 of this test. The consistency of the two soil should be such that the required number of strikes is between 15 and 35 times when the closing length is 13mm (1 time for more than 25 times and 1 time for less than 25 times). Then the corresponding moisture content of the samples under each blow was determined.

4 Result Arrangement

4.1 According to Equation (T0170-1), calculate the corresponding water content of the sample when it is closed under each stroke:

(T0170-1)

Where: wn -- n hit the moisture content of the sample (%), calculated to 0.01;

mn -- n hit the mass of the sample (g);

Ms -- dry soil mass of the sample (g).

4.2 The test record format is shown in Table T0170-1

Table T 0170-1 Test record of liquid limiting disc instrument method

Project No. Experimenter

Soil sample description calculator

Test date checked

Box no. 1 2

Box mass (g) (1) 20 20

Box + wet soil mass (g) (2) 38.87 40.54

Box + dry soil mass (g) (3) 35.45 36.76

Moisture mass (g) (4)=(2)-(3) 3.42 3.78

The most dry soil (g) (5)=(3)-(1) 15.45 16.76

Liquid limit water content (%) (6) = (4)/(5) 22.1 22.6

Average liquid limit water content (%) (7) 22.4

4.3 According to the test results, the curve is drawn with water content as the ordinate and log of hits as the abscissa, as shown in FIG. T 0170-3. The water content corresponding to 25 hits on the check curve is the liquid limit of the sample.

FIG. T 0170-3 Relation curve between water content and number of strokes

4.4 Precision and tolerance difference.

Two parallel determinations shall be performed in this test, and the arithmetic mean shall be taken and expressed as an integer (%). The allowable difference is less than or equal to 2% for high liquid limit soil and 1% for low liquid limit soil.

5 report

5.1 Identification and classification of soils.

5.2 Soil liquid limit.

Provisions that

The most common methods for determining liquid limit and plastic limit of soil are disc method and rolling method, respectively. At present, there are still two kinds of cutter for disc instrument, one is ASTM cutter (referred to as A cutter), and the other is Karlner cutter (referred to as C cutter). The test results show that the liquid limit value measured with A cutter is about l0% lower than that measured with C cutter. In addition, the hardness of the disc instrument base also affects the test results 3 card test to obtain the liquid limit of undrained shear strength is 2 ~ 3kPa, for this standard ASTM D423 adopted by the disc instrument specifications, in order to facilitate international technical exchange.