After seven days of concrete curing, the concrete will be removed for 28 days with 75% strength and 24 hours with 33.5MPa.
The test block under the same conditions is the age corresponding to the daily average temperature of 600 degrees/day, regardless of the age of 0 degrees or below, and the equivalent age should not be less than 14 days and should not be longer than 60 days. When pouring concrete, the test blocks should be standard curing test blocks, formwork removal test blocks and conditional curing test blocks.
The standard curing test block is a standard cube test block, and the standard condition (temperature 20 2. Standard curing means that the standard cube specimen is cured for 28 days under standard conditions (temperature 20 2 and relative humidity above 95%). The curing age under the same conditions can be accumulated day by day according to the daily average temperature.
Extended data:
Precautions for concrete block:
1. Apply a thin layer of mineral oil or other isolation agent that does not react with concrete on the inner surface of the test mold, so that the concrete in the test mold can be easily taken out after it is finally solidified.
2. Vibrate and compact the concrete. Concrete with slump not greater than 70_ should be vibrated by vibration, and there should be no jumping during the test. The vibration should continue until the concrete surface becomes slurry, and should not be excessive.
3. If the slump is greater than 70_, it should be tamped manually with a tamper. When making, the concrete mixture should be put into the test mould twice, and the thickness of each layer should be roughly equal. Tamping should be carried out evenly from the edge to the center along the spiral direction.
4. When tamping the concrete at the bottom, the tamping rod should reach the bottom of the trial; When tamping the upper layer, the tamping rod should pass through the upper layer for 20 _-30 _, and then be inserted into the lower layer. Tamping, tamping rod should be vertical, shall not be tilted. Finally, insert and remove it several times along the inner wall of the test die with a spatula.
5. Immediately after molding, cover the surface with impermeable film. Samples with standard curing shall be allowed to stand at 15-25 degrees Celsius for one day and two nights.
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