① In concrete projects, the following early strength agents can be used; chloride salts, sulfates, organic amines, and formates.
② Early-strength and early-strength water-reducing agent can be used for steam-cured concrete and construction under normal temperature, low temperature and negative temperature (the minimum temperature shall not be lower than 5℃) Concrete projects with early strength or anti-slurry requirements.
③ In the following structures, chlorine salts, composite early-strength admixtures containing chlorine salts and early-strength water-reducing agents shall not be used in reinforced concrete.
Structures used in environments where the relative humidity is greater than 80%, structures in areas where the water level rises and falls, open-air structures or structures that are often exposed to water, often with an ambient humidity of 60 Structure above ℃. Structures connected to galvanized steel or aluminum iron, as well as structures with exposed embedded iron parts without protective measures. Structures in contact with corrosive media such as acid, alkali or sulfuric acid. Structures reinforced with cold-rolled steel bars or cold-drawn low-carbon steel wire. Electrolysis workshop and structures within 100m of the high-voltage DC power supply. Structures close to high-voltage power sources, such as pipe stations, substations, prestressed mixed spring soil structures, structures containing active alkali aggregates.
④ Early-strengthening agents containing strong electrolyte inorganic salts, such as sulfates and other early-strengthening water-reducing agents, shall not be used in the following structures:
Structures in contact with galvanized steel or aluminum iron, as well as structures with exposed embedded iron parts without protective measures. Factories with DC power supply and reinforced concrete structures using electrified transportation facilities. Structure containing active alkali aggregates.
⑤ For concrete projects that have special requirements for the durability or other properties of concrete, the type and dosage of early-strength agent or early-strength water-reducing agent should be selected through Test confirmed.
⑥ The dosage of commonly used early strength agents should not exceed the following regulations: prestressed concrete, sodium sulfate 1, triethanolamine 0.05%, reinforced concrete, after drying In the environment, 1% chlorine salt, 2% sodium sulfate, 3% sodium sulfate combined with retarding water reducing agent, 0.05% triethanolamine, in humid environment, 1.5% sodium sulfate, 0.05% triethanolamine. For concrete with corrosion requirements, sodium sulfate 1%. Unreinforced concrete chlorine salt 3%.
⑦ In prestressed concrete, the total amount of chloride salts carried by other materials should not be greater than 0.1% of the weight of cement. In reinforced concrete in humid environments, it should not be greater than 0.25% by weight of cement. Chloride content is measured as anhydrous calcium chloride.
⑧ Chloride salt, crystalline sodium sulfate and organic amine early strength agent can be used in solutions. If necessary, hot water at 40-70°C can be used to accelerate dissolution, and the solution should be kept uniform. ‘
⑨ Sodium sulfate solution should be prepared and used immediately. The concentration of the solution should not be greater than 20%. If there is crystallization precipitation before use, it should be stirred with heat to make it complete. Dissolve.
⑩ If the composite early strength agent mixed with powder is agglomerated by moisture, it should pass through a 0.63mm sieve before use. When the powder early strength agent is added to the mixer, it should be dry-mixed with the cement aggregate and then added with water. The mixing time should not be less than 3 minutes.
⑾ When using natural maintenance, it should be covered with plastic thin wax, and at low temperatures, it should be covered with moisturizing materials. When steam curing is used, the steam curing system should be determined through experiments. </p
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