Regarding the proportioning principle of concrete admixtures, many people will be confused. Is there a specific parameter and how much should be added? Industry experts first told him that everyone must follow the manufacturer’s strong instructions. Recommended dosage. Polycarboxylic acid has stricter requirements for raw materials. The dosage of admixtures has a lot to do with your raw materials. The greater the mud content of the sand, the greater the dosage of your admixtures. The mud can absorb For admixtures, the dosage recommended by the manufacturer is basically based on the trial mix certification. Look at the original slump and time-dependent damage, concrete setting time and compressive strength. The dosage still needs to be confirmed by yourself. For polycarboxylic acid admixtures, it is recommended that the sand mud content be less than 1.6%.
Is it not necessary to take into account admixtures when calculating the mix ratio? Is it not necessary to take into account admixtures when confirming the standard formulation?
For example, if it is a high-efficiency water-reducing admixture, the water reduction rate is 16%, no need When adding admixtures, the water demand is 215 kg/m3. The water demand for adding admixtures is equivalent to 215-215*16%=177 kg/m3. If the concrete water-cement ratio is 0.45, the original concrete usage If 215/0.45=478 kg/m3, the amount of concrete mixed with admixtures is equivalent to 177/0.45=393 kg/m3. This is a standard mix ratio, but when it is to be changed to a construction mix ratio, a trial mix certification must be carried out. Taking into account the moisture content of the raw materials, the trial mix certification must be carried out according to the recommended dosage of the admixture manufacturer.
Parameters such as concrete admixtures, mortar admixtures, etc. are determined based on the amount of commonly used concrete, such as the use of concrete retardant water-reducing admixture (according to 4% of the concrete amount used) -8%) means that for every 150kg of concrete used, 4-8kg of retarding water-reducing admixture should be used, and other materials and stones cannot be counted.
You can refer to GB8076 for detailed mix ratios and tests. Methods, evaluation criteria, etc. can all help experimenters to better analyze and calculate higher quality.
Mix ratio
The standard concrete mix ratio is designed according to JGJ55. The tested concrete mixed with non-air-entraining admixtures has the same proportions of concrete, sand and stone as its matching standard concrete. The mix proportion design should meet the following requirements:
a) Concrete usage amount: The enterprise concrete usage amount for standard concrete mixed with performance water-reducing agent or underwater concrete agent and inspected concrete is Computer Butler kg/M3 ;
The standard concrete mixed with other admixtures and the concrete usage of the inspected concrete enterprises is 340 kg/M3.
b) Sand rate: The sand rate of standard concrete and tested concrete mixed with performance water-reducing agent or underwater concrete agent are both 44% to 56%; mixed with others
The sand rate of the standard concrete with admixtures and the tested concrete is 41% to 50%; however, the sand rate of the tested concrete with air-entraining water-reducing agent or air-entraining agent is wider than that of the standard concrete. The sand rate is 1% to 3% lower.
c) Additive dosage: According to the manufacturer’s specific dosage.
d) Water demand: The slump of the standard concrete mixed with performance water-reducing agent or underwater concrete agent and the tested concrete is controlled at (260±12) mm, and the water demand is the slump of ( The minimum water requirement is 260±12) mm; the slump of standard concrete mixed with other admixtures and tested concrete is controlled at (90±12) mm. Water demand includes the flow of water contained in liquid admixtures, sand, and stone raw materials.
</p
微信扫一扫打赏
