The mixing of castable is a key link in the construction process, which directly affects the performance and construction quality of castable. The following are the main points that should be paid attention to when mixing castable:

I. Mixing equipment

Use forced mixer: Forced mixer can ensure uniform mixing and avoid material delamination.

Equipment cleaning: Mixers, tools and conveying equipment must be kept clean and free of residues, so as to avoid mixing impurities.

II. Mixing water

Water quality requirements: the mixing water should be clean drinking water with a pH value of 6-8. The chloride ion concentration of mixing water in coastal areas should not be greater than 0.03%(300ppm).

Water temperature control: In winter construction, the water temperature can be appropriately heated, but it shall not exceed 40℃.

III. Water addition control

Strictly control according to the instructions: the water addition should be strictly controlled according to the product instructions, generally not exceeding the maximum limit.

Use as little water as possible: on the premise of ensuring construction fluidity, the amount of water added should be less than more.

IV. Stirring time

Stirring time shall not be less than 5 minutes: dry mixing shall be carried out for 1-3 minutes, then 80% water shall be added for 2-3 minutes, and finally the remaining water shall be adjusted according to the degree of dryness and wetness.

Total mixing time: the total mixing time shall be no less than five minutes to ensure uniform materials.

V. Construction time

The stirred castable should be used up within 30 minutes: the service time should be shortened appropriately in high temperature and dry environment.

Avoid secondary stirring: castable that has been initially set or caked shall not be mixed with water again for use.

VI. Construction environment

Avoid high temperature and low temperature: the construction environment temperature should be kept above 5℃ to avoid condensation caused by low temperature.

Shading in summer: In summer, it is necessary to build a sunshade to prevent direct sunlight.

VII. Other considerations

Tool cleaning: construction tools such as mixers, buckets, tool shovels, etc. should be cleaned in advance to avoid mixing impurities.

Template treatment: the template should be stable, smooth and coated with release agent.

Vibrating requirements: After pouring the castable into the mold, it should be vibrated by layers with vibrating rods, and the height of each layer should not be greater than 300 mm.

By strictly following the above mixing precautions, the construction quality and service life of castable can be effectively ensured.