TD720-2 Asphalt mixture line shrinkage coefficient tester

TD720-2 asphalt mixture line shrinkage coefficient test instrument was developed by Hebei Tianqi Xingzi Testing Equipment Co., LTD in accordance with "Asphalt Mixture Line Shrinkage Coefficient Test" T0720-1993 in JTGE20-2011 "Test Rules for Asphalt Based Asphalt Mixture of Highway Engineering". It is suitable for measuring the linear shrinkage coefficient of asphalt mixture.

TD720-2 asphalt mixture line shrinkage coefficient test instrument Technical parameters:

1, temperature control table temperature control range: -50 ~ 99.9℃

2. Power supply voltage: 220V

3, temperature control accuracy: ±0.1℃

4, water bath size: 300×200×150

5, heating power: 1000W

6, refrigeration power: 280W

7, equipment temperature control range: -50 ~ 60℃

8, the length of the specimen measured by the contraction instrument: 200±20mm

9, the maximum range of the dial gauge: 0-12.5mm

Iii. TD720-2 asphalt mixture line shrinkage coefficient tester using steps:

1 Preparations

1.1 Plate shaped specimens of 300mmx300mmx50mm are made by wheel rolling according to the production method of T0703 asphalt mixture test pieces of this code, and then cut into prismatic specimens of 20mmx20mmx200mm in sequence with the sawstone machine. A set of test pieces should not be less than 3.

1.2 Measure the size of the test piece with a caliper. The length is the average value of the two measurements on the opposite side (L), and the height (/0 and width (6) are the average value of the two ends and the three middle directions, accurate to 0.1mm. The difference between the cut specimen and the standard size of the specimen should not exceed ±2mm in length and ±1mm in height and width.

1.3 Determine the density, voidage and other physical indexes of asphalt mixture according to this procedure.

2 Test Procedure

2.1 Glue a metal probe to the center of the two ends of the specimen. The one end in contact with the micrometer is a flat-head shaped probe, and the other end is a hemispherical probe. Glue it well with 502 binder and wait for it to solidified and stick with a little pressure by hand. Note that the probe should be accurately adhered to the central axis at both ends of the specimen, and the probe plane should be perpendicular to the axis. The specimen with the well bonded probe is placed on a glass plate.

2.2 Human methanol aqueous solution should be injected into the constant temperature tank as the refrigerant, the depth should be more than 20mm above the specimen, and. Control the temperature of the sink to the test starting temperature (+10℃) for insulation.

2.3 Move the glass plate and specimens (3 in a group) in a constant temperature water tank. The overhead height of the glass plate should be no less than 30mm from the bottom surface, and the distance between each specimen should be no less than 10mm. During the whole test process, the upper and lower positions of the specimen shall not be reversed. Keep constant temperature for 30min in the water tank where the test temperature started.

2.4 After constant temperature, the specimen is quickly removed from the water tank. With one hand, the measuring rod of the contractile meter (or displacement meter) is pulled out. With the other hand, the specimen is placed on the left end of the test frame close to the measuring rod, and the inner side close to the positioning baffler. Accurate to 0.001mm. Then, the specimen was quickly returned to the methanol solution. The time from taking the specimen out of the constant temperature tank to the reading of the micrometer should not exceed 5s. Otherwise, the specimen should be put back into the sink to hold heat for about 10min before retesting.

2.5 Put the specimens back to the original position in the water tank. After all the three specimens are measured, the water tank starts to cool down at a cooling rate of 5℃/h(or other prescribed cooling rate) until the predetermined end temperature of -30℃, the cooling is stopped, and the temperature is kept for 30min under this condition. Repeat the determination of 2.4 and take the final reading Le, accurate to 0.001mm.

2.6 is to measure the shrinkage coefficient in different temperature ranges. After the temperature drop is 10℃ and the constant temperature is 30min, the length of the specimen at each temperature can be measured according to the method in 2.4 before further cooling.

Iv. Calculation of results of TD720-2 asphalt mixture line shrinkage coefficient tester:

4.1 The average shrinkage strain and the average shrinkage coefficient of the cooling interval are calculated according to equations (T0720-1) and (T0720-2).

Epsilon e= (Le-L0) /L0

C = epsilon e / Δ T

εe -- mean shrinkage strain in the above equation;

Length of specimen after shrinkage at Le -- 20℃ (mm);

The original length of the specimen at L0 -- 10℃ (mm);

C -- average linear shrinkage coefficient of asphalt mixture;

ΔT -- the temperature range, the difference from the initial temperature (+10℃) to the final temperature (-30℃), is 40℃.

4.2 When measuring the temperature interval, the shrinkage coefficient of each temperature interval can be calculated according to the equations (T0720-1) and (T0720-2). With the median temperature as the representative temperature, the contraction coefficient curves of different temperatures can be obtained.

For the same asphalt mixture, at least 3 specimens should be tested in parallel. When the difference between the maximum value and the minimum value does not exceed 20% of the average value, the average value should be taken as the test result.

V. Maintenance of TD720-2 asphalt mixture line shrinkage coefficient tester:

TD720-2 asphalt mixture line shrinkage coefficient tester shall be regularly maintained during use and prevention:

1. Contents of annual maintenance and maintenance inspection

1. Check, maintain and calibrate electrical control components. Repair and replace damaged ones.

1.2. Check and tighten electrical control cabinet and related circuit wire contacts.

1.3 Check whether the evaporating and condensing tubes are corroded and scaled. If scale is formed, chemical scale removal is recommended.

1.4 Under the premise of normal maintenance and construction inspection, the whole machine shall be unified debugging. Make written records according to the test indexes of normal debugging. And in accordance with the requirements of the owner or Party A visa acceptance procedures.

2. Inspection in operation

2.1 After the unit is in operation, personnel shall be dispatched to carry out on-site inspection of the product once a month.

2.2. Check whether there is any abnormal situation in the operation of the unit. If the situation should be found in time to find out the reason, and eliminate.