How to ensure the compactness of the concrete specimen when it is formed

First, put half of the concrete in the test block mold, tamp it with a thicker steel bar, and then put the test block mold on the ground a few more times, and then fill the mold with concrete, and repeat the above two steps.

Before each test block, apply a thin layer of oil or release agent to the inner wall of the test chamber. When disassembling, loosen the wing nut on the loose joint bolt, loosen the wing nut on the shaft, and detach the side template groove together with the loose joint bolt, the side template can be removed, and after each demoulding, the slag on the surface of each part should be wiped clean and coated with anti-rust oil.

Construction and use.

This model is composed of the bottom template, the side template, the partition shaft, the bracket joint, the bolt and the wing nut and other parts, the bottom template is made of high-strength cast iron, the side template, the partition plate is supported by harder carbon knot steel, and the bracket is fixed on the low template. The jointed bolt is connected to the bracket with a cylindrical pin, and the axis of the cylindrical pin can be rotated.

Before each test block, apply a thin layer of oil or release agent to the inner wall of the test chamber. When disassembling, loosen the wing nut on the loose joint bolt, loosen the wing nut on the shaft, and detach the side template groove together with the loose joint bolt, the side template can be removed, and after each demoulding, the slag on the surface of each part should be wiped clean and coated with anti-rust oil.

The above content reference: Encyclopedia - concrete mold test.

You can buy a small portable plate vibrator, and when you vibrate, pick some stones and put them in, and the density should be okay.

The requirements for making concrete specimens are as follows:

1) Concrete specimens should be made of steel molds;

2) As a specimen for evaluating the strength and quality of concrete of structural components, it should be randomly sampled at the pouring site of concrete, but a group of specimens must be taken from the same (plate) mixing;

3) The minimum size of the concrete cube specimen allowed to be used in the construction of Kaiji should be.

According to the maximum particle size of the aggregate, when a non-standard size specimen is used, the compressive strength value should be multiplied by the conversion coefficient and converted into the compressive strength value of the standard size specimen. The minimum allowable size of the specimen and its strength coefficient shall comply with the regulations.

4) Before the production of the test block, the consistency and slump of the same batch of concrete mixture should be measured and recorded.

The mold test should comply with the provisions of the technical requirements in the "Concrete Mold Test" (JG3019). Self-inspection should be carried out on the mold test regularly, and the self-inspection cycle should be three months.

1. Before making the test piece, the test mold should be wiped clean, and the inner wall should be coated with a release agent.

2. When the specimen is formed with a vibrating table, the concrete mixture should be loaded into the test mold at one time, and the charging should be slightly inserted and pounded along the inner wall of the test mold with a spatula and the concrete mixture should be higher than the upper mouth of the test mold, and the test mold should be prevented from beating freely on the vibrating table when vibrating. The vibration should continue until the concrete surface is slurryed, scraping off the excess concrete and smoothing it with a spatula.

3. The shaking table should comply with the provisions of the technical requirements in the "Vibrating Table for Concrete Laboratory" (JG T3020).

4. When the specimen is manually inserted, the concrete mixture should be loaded into the trial mold in two layers, and the thickness of each layer should be roughly equal. The steel tamper used for insertion should be: 600mm long, 16mm in diameter, and rounded at the end.

The smashing is carried out evenly from the edge to the center in the direction of the spiral. When inserting the bottom layer, the pounding should reach the bottom surface of the test mold; When inserting the upper layer, the tamper should penetrate the lower layer to a depth of about 20 30mm. When inserting, the vibrating rod should be kept vertical, not tilted, and inserted several times along the inner wall of the test mold with a spatula.

The number of insertions in each layer should be determined according to the cross-section of the specimen, generally not less than 12 times per 100c cross-sectional area. After smashing, scrape off the excess concrete and smooth it with a spatula.

5. The standard maintenance specimen should be kept at a temperature of 20 5 degrees for one day and two days, and then numbered and dismantled. After mold removal, the specimen should be immediately cured in a standard curing room with a temperature of (20 2) degrees and a humidity of more than 95% or in a non-flowing Ca(OH)2 saturated solution at a temperature of 20 2 degrees. In the standard curing room, the specimens should be placed on the rack, and the distance between them should be 10 20mm, and the specimens should be avoided from being directly brushed with water.

The specimen is cured under the same condition as the structure or component, and the surface should be covered after molding, and the demoulding time of the specimen can be the same as the demoulding time of the actual component, and the specimen still needs to maintain the same condition after demoulding.

The production of concrete specimens is one of the important links in the quality control of concrete materials, and its production process needs to strictly follow certain steps and specifications. The following are the steps for making mu yu for general concrete specimens:

1.Material preparation: According to the design requirements, prepare concrete raw materials, including cement, sand, aggregate and water, etc.

2.Mold trial preparation: Select the test mold that meets the standard, and clean and oil it according to the requirements.

3.Mixing and mixing: According to the design mix ratio, the raw materials such as cement, sand, aggregate and water are mixed and mixed until a uniform concrete slurry is obtained.

4.Filling mold compaction: the concrete slurry is poured into the mold trial, and the vibrator is used for compaction, so that the concrete slurry can fully fill the inside of the mold trial and avoid defects such as voids and bubbles.

6.Curing: The specimen is placed in an environment of constant temperature and humidity for curing, so that the concrete specimen can give full play to its strength and durability.

7.Specimen identification: Identify the necessary information such as the date of production and the specimen number on the specimen.

The above are the main steps of general concrete specimen production. It should be noted that in the process of specimen production, it is necessary to pay attention to the accuracy of the material mix ratio, the selection and preparation of the mold test, the adequacy of the compaction process, the curing time and temperature of the specimen, etc., so as to ensure that the test vertical key parts produced can accurately reflect the performance and quality of concrete materials.

Answer]: Paragraph 4 of BGB T 50081-2002 "Test Method for Mechanical Properties of Ordinary Concrete" stipulates that the concrete forming method is determined according to the density of the concrete mixture, and the concrete with a slump and slip degree of no more than 70mm should be vibrated and compacted; If it is more than 70mm, it should be manually tamped with a tamper; To inspect the concrete of cast-in-place concrete or prefabricated components, the specimen forming method should be the same as that of the old method used in the real letter cluster.

Answer]: B Highway Engineering Cement and Cement Concrete Test Regulations (JTG E30-2005) during the shrinkage section of the key test, the specimen should have no change in quality, and the amount of quality in 180d should not exceed 10g, otherwise it will be invalid.