CBR Bearing Ratio Tester

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1、 Purpose:

The bearing ratio tester is suitable for conducting bearing ratio tests on various soils and mixtures (soil with particle size less than 40mm) after compaction in the specified test tube mold to determine the bearing capacity of the designed pavement, pavement base layer, subbase layer, and subgrade material layer. It is one of the necessary instruments for geotechnical testing. This instrument complies with the national standard (GB/T50123-1999) and the Ministry of Transport standard (JTJ051-93).

2、 Main technical parameters:

1. Large load: 30KN, 50KN (optional)

2. Load speed: 1.0mm/min; 1.25mm/min

3. Penetrating rod: Φ 50mm * 100mm

4. Workbench: Φ 170mm

5. Workbench travel: 50mm

6. Test piece mold: Φ 152mm * 170mm (120, 166)

7. Instrument size: 310 * 310 * 930mm (L * W * H)

8. Instrument weight: 100kg

3、 Instrument composition:

The instrument for CBR bearing ratio test consists of CBR host, force measuring ring and penetration rod, loading plate, dial gauge, expansion measurement device, etc. The load-bearing ratio tester has the characteristics of small volume, high output, and easy operation. In addition to conducting load ratio tests, this instrument can also perform water immersion expansion tests on specimens.

Immersion expansion accessories (purchased separately)

1. Test tube: 9 pieces

2. Permeable board: 9 pieces

3. Porous plates: 9 pieces

4. Load plate: 36 pieces

5. Penetration rod: 1 piece

6. Dial gauge holder: 9 pieces

7. Percentage table: 9 pieces

Technical Requirements for Load Ratio Tester - SBR Indoor Load Ratio Tester Manual - Instrument Composition:
The instrument for CBR bearing ratio test consists of CBR host, force measuring ring and penetration rod, loading plate, dial gauge, expansion measurement device, etc. The load-bearing ratio tester has the characteristics of small volume, high output, and easy operation. In addition to conducting load ratio tests, this instrument can also perform water immersion expansion tests on specimens.
Immersion expansion accessories (purchased separately)
1. Test tube: 9 pieces
2. Permeable board: 9 pieces
3. Porous plates: 9 pieces
4. Load plate: 36 pieces
5. Penetration rod: 1 piece
6. Dial gauge holder: 9 pieces
7. Percentage table: 9 pieces
Technical Requirements for Load Ratio Tester - Maintenance Manual for SBR Indoor Load Ratio Tester:
1. After each use, the instrument should be cleaned immediately.
2. After one year of use, the lubricating grease in the gearbox should be replaced with new lubricating grease, and regular maintenance should be carried out in the future.
Technical requirements for bearing ratio tester - Instructions for use of SBR indoor bearing ratio tester:
1. Turn on the power switch, operate the instrument, check if the working condition of the instrument is normal, check if the handle is in and out, and if the rotation is normal. If everything is normal, prepare to start the test.
2. Prepare specimens according to the bearing ratio test method specified in JTJ075-85 "Test Code for Highway Pavement Base Materials".
3. Measurement of water swelling:
A、 Place the moisture cured specimen on a porous plate equipped with an adjusting rod, and apply sufficient load plate on the plate to ensure that the pressure on the specimen surface is equal to the pressure on the road surface of the material layer.
B、 Place the test tube and porous plate together in the water tank (without draining water first) and tighten the mold with a pull rod. Install a dial gauge and read the initial reading.
C、 Pour water into the sink to allow it to freely enter the top of the specimen. During the saturation period, the water in the sink should be kept 25mm above the top surface of the specimen. Typically, the specimen needs to be soaked for 96 hours.
D、 When the soaking time is up, read the dial gauge and calculate the expansion amount.
AV=change in specimen height after immersion in water/original specimen height (120mm) x 100%
E、 Take out the sample from the sink, pour out the water on the sample, let it stand for 15 minutes to drain, then remove the additional load, porous plate, bottom plate, and filter paper, and bear the weight M to calculate the depth and density changes of the sample.
4. Penetration test:
A、 Place the saturated water test specimen on the lifting plate of the testing instrument, adjust the alignment between the penetration rod and the force measuring ring, and place a predetermined number of load plates around the penetration rod.
B、 First, apply a 45N load to the penetration rod with the handwheel, and then adjust the force measuring ring and the dial gauge for measuring deformation to zero.
C、 Load and press the handwheel, record the penetration rate at certain readings (20, 40...) of the force gauge, and note that the penetration rate is 2.5mm, with more than 8 readings. The bearing ratio for total penetration rates of 2.5 and 50mm is:
Bearing ratio C=unit pressure/7 or 10.5 × 100%

User Manual for CBR Bearing Ratio Tester

1、 Purpose:

The Bearing Ratio (CBR) tester is used to conduct bearing ratio tests on various soil and pavement base and bottom materials after making specimens in specified test tubes.

The large particle size of the mixture should be controlled within 25mm and not exceed 40mm.

2、 Main parameters of the instrument:

1. Bearing ratio tester: speed 1mm/min, high pressure 3T.

2. Penetration rod: End face diameter 50mm, length 100mm.

3. Porous plate: two pieces

4. Load plates: 4 pieces (outer diameter 150mm, inner diameter 52mm, each weighing 1.25kg)

5. Test tube: inner diameter 152mm, height 170mm.

6. Force measuring ring: 30KN, height 170mm.

3、 Instrument usage method:

1. Turn on the power switch, operate the instrument, check if the working condition of the instrument is normal, and check if the handle rotates in and out normally. If everything is normal, prepare to start the test.

2. Prepare specimens according to the bearing ratio test method specified in JTJ057-85 "Test Code for Highway Pavement Base Materials".

3. Measurement of water swelling:

(1) Place the moisture cured specimen on a porous plate equipped with an adjusting rod, and apply sufficient load plate on the plate to ensure that the pressure on the specimen surface is equal to the pressure on the road surface of the material layer.

(2) Place the test tube and porous plate together in the sink (without draining water first), tighten the mold with a pull rod, install a dial gauge, and read the initial reading.

(3) During the soaking period, the water level in the tank should be kept 25mm above the top surface of the specimen, and the specimen is usually soaked for 96 hours.

(4) During the soaking period, read the dial gauge and calculate the expansion rate.

(5) Take out the specimen from the sink, pour out the water on the surface of the specimen, let it stand for 15 minutes to drain, then remove the additional load and porous plate, bottom plate, and filter paper, and weigh M to calculate the humidity and density changes of the specimen.

4. Penetration test:

(1) Place the specimen that has completed the immersion test on the lifting plate of the testing instrument, adjust the alignment between the penetration rod and the force measuring ring, and place a predetermined number of load plates around the penetration rod.

(2) First, apply a 45N load on the penetration rod with the handwheel, and then adjust the dial gauge for measuring the deformation of the force measuring ring to zero.

(3) Load the pressure handwheel and record the penetration rate when certain readings (20, 40...) are on the force gauge. Note that when the penetration rate is 2.5mm, there can be more than 8 readings, and the total penetration rate should exceed 7mm.

(4) Calculate and plot the pressure penetration curve, and calculate the bearing ratio at penetration rates of 2.5 and 50mm.

4、 Maintenance:

1. After each experiment, the instrument should be cleaned immediately.

2. After one year of use, the lubricating grease in the gearbox should be replaced with new grease, and regular maintenance should be carried out in the future.