Manufacturer of early cracking testing equipment for self compacting concrete blade restraint

Manufacturer of early cracking testing equipment for self compacting concrete blade restraintThe basic principle of the flat blade constraint method for determining indicators is to use 7 parallel flat blade edges in the flat plate test mold to induce equivalent constraint cracking of the tested material, which can quickly crack the specimen under the same experimental conditions. The blade constraint method uses a flat thin plate specimen with dimensions of 800mm × 600mm × 100mm as the standard specimen. The surface area of the concrete specimen is 0.48m2, and a stress induction generator is placed inside.

Specific testing equipment for early cracking test mold constrained by self compacting concrete blade:

1. The mold is made of steel, and the four sides of the mold are welded with channel steel. The four sides of the mold are fixed to the bottom plate with bolts. The bottom plate adopts a hard board with a thickness of not less than 5mm, and a polyethylene film isolation layer is laid on the surface of the bottom plate.

2. There are seven stress induction generators in the mold, which are welded together with 50mm × 50mm and 40mm × 40mm stainless steel angle steel and 5mm × 50mm stainless steel plate, and fixed parallel to the short side of the mold and the bottom plate.

3. Fan: The fan used can achieve a wind speed of 5m/s at the center of the specimen surface.

4. The reading microscope should use a 40x reading microscope (with a division value of 0.01mm) to measure concrete cracks.

Mold test steps and precautions for early cracking test of self compacting concrete blade restraint:

(1) The experiment should be conducted in a constant temperature and humidity chamber, which should be able to maintain the room temperature at 20 ± 2 ℃ and the relative humidity at 60 ± 5%.

(2) Pour the concrete into the mold, and after leveling, the surface of the concrete should be slightly higher than the mold frame. Use a flat surface vibrator or insert a vibrator to control the vibration time and prevent over vibration and under vibration.

(3) After vibration, use a trowel to level the surface so that the aggregate is not exposed and the surface is flat.

(4) After 30 minutes of forming the test piece, the electric fan should be immediately adjusted to blow directly onto the surface of the test piece, so that the wind speed at the center of the test piece surface is 5m/s, and the wind direction is parallel to the surface of the test piece.

(5) Starting from the time of mixing and adding water to the concrete, and measuring cracks within 24 hours. The length of the crack shall be based on the visible crack to the naked eye. The length shall be measured with a steel ruler, and the straight distance between the two ends of the crack shall be taken as the crack length. The length of each crack should be measured. When there are two cracks on a blade, the lengths of the two cracks can be added together to convert it into one crack. The crack width should be measured using a reading microscope with a magnification of at least 40 times (division value of 0.01mm), and the large width of each crack should be measured.

(6) Calculate the average cracking area, number of cracks per unit area, and total cracking area per unit area based on crack data measured 24 hours after pouring concrete.