1. Product description
1. The concrete rebound Tester uses a spring to drive the hammer and bounces the concrete surface through the bullet rod to restore the instantaneous elastic deformation of the restoring force, so that the hammer drives the pointer to bounce back and indicates the distance of the bounce. The rebound value (the ratio of the rebound distance to the distance from the bounce hammer to the bounce rod before impact, calculated as a percentage) is used as one of the indicators related to the compressive strength of concrete to estimate the compressive strength of concrete. It is an instrument for non-destructive testing of the compressive strength of concrete in structures or components . Because the rebound hammer is light , flexible, cheap, does not need power supply, and is easy to master, it is very suitable for on-site construction sites. In addition, the establishment and implementation of the corresponding rebound hammer verification regulations and rebound method testing concrete compressive strength technical regulations , to ensure its detection accuracy, has been widely used in various industries in our country.
2. The standard energy of the AL-150L rebound hammer produced by our factory is 2.207J. Its technical performance and main parameters are in line with the provisions of the national metrological verification regulations "Concrete rebound hammer" (JJG817-2011 ). Its main indicators are as follows:
3. Operation, maintenance and calibration of cement Hardness Tester
(1) Operation
1. Put the bullet dry against the brick-like surface, press the instrument lightly to release the button, when the pressure is relaxed, the bullet dry sticks out, and the hook hangs the bullet hammer .
2. Make the axis of the instrument always perpendicular to the measuring point on the brick spline surface and test the pressure slowly and evenly. After the bullet hammer is unhooked and impacts the bullet hammer , when the bullet hammer rebounds and drives the pointer to move backward to a certain position, The indication scale line on , which isthe pointer the rebound value.
3. Keep the instrument against the surface of the brick sample for reading and record the rebound value. If conditions are not conducive to reading, the movement can be , and the instrument can be moved to another place for reading.
4. Gradually depressurize the instrument, so that the ejection rod protrudes from the instrument, and wait for the next use.
(2) maintenance
Routine maintenance should be carried out when one of the following situations occurs:
1. The number of bounces exceeds 15 groups of brick samples.
2. When there is doubt about the detection value.
3. Steel drilling rate customization is unqualified.
Routine maintenance methods should meet the following requirements:
1. Unhook the hammer and take out the movement, and then remove the spring lever (take out the buffer spring inside) and the triple parts (hammer, spring and spring seat).
2. Clean the parts of the movement with gasoline, especially the center guide rod , the inner hole and impact surface of the ejection hammer and the ejection rod. After cleaning, apply a thin layer of No. 20 engine oil on the center guide rod. Parts must not be oiled.
3. Clean the inner wall of the casing, remove the scale, and the friction force of the inspection pointer should be 0.5±0.1N.
4. Do not turn the firmly positioned zero adjustment screw on the tail cap.
5. Do not make your own or replace parts.
6. Calibration test should be carried out as required after maintenance, and the calibration value should be 74±2
(3) Calibration
In case of any of the following situations, the inspection form approved by the competent department shall be sent
One-bit proofreading, if the proofreading is qualified, there should be a verification certificate:
1. Before the new instrument is used.
2. Exceeded the validity period of the certification (the validity period is half a year).
3. The cumulative number of bounces exceeds 6000 times.
4. After routine maintenance, the rated value is unqualified.
5. Suffering severe impact or other damage.
4. Testing technology
(1) Sampling
1. Sampling shall be carried out according to the provisions of GB5101-85.5.1 during factory acceptance inspection . For other acceptance inspections, random . The number of brick samples is 10.
2. If the selected brick sample has one of the following conditions, the next adjacent brick sample should be selected as a substitute:
a. Underfired bricks, crisp bricks and threaded bricks.
b. Bricks with unqualified appearance quality.
c. Brick samples that cannot measure 10 rebound values due to scorching.
3. The following situations should be dealt with before the test:
a. In case of rain or blisters, it should be dried.
b. The surface of the brick sample should be flat, otherwise it should be smoothed with a grinding wheel, and the dust should be removed with a brush.
(2) Test device
The test setup consisted of a brick pier and a lever press (Fig. 2).
1. When laying brick piers, it is necessary to ensure that the dimensions of the concave corners where the brick samples are placed are accurate, and the three surfaces are perpendicular to each other and flat.
2. The lever should be such that the pressure exerted by the weight lever mechanism on the brick sample is 500+50N.
(3) Measuring point location
It is advisable to measure the springback value of each brick sample at five points on the two strip surfaces When one of the following situations occurs at the brick sample measuring point position, it should be avoided, and another measuring point should be selected next to it :
a. burnt flowers
b. Crack
c. sticky bottom
d. Pits and lime burst points, etc.
