Additives that accelerate or slow down the process of concrete hardening. The action of the R.t.b. Based on their effect on cement hydration processes.
Additives that accelerate hardening are used both in prefabricated and in monolithic construction to reduce the time of construction, work, heat treatment of concrete, etc. It is advisable to use them in the composition of complex additives, one of the components, improving the efficiency. Quality indicator bet. Mixture or concrete, slows down the growth of the strength of the latter. The hardening accelerators are HK (calcium chloride), CH (sodium sulfate), CH (sodium chloride, P (potash), etc. The use of hardening accelerators is accompanied by an increase in the electrical conductivity of concrete. -fry additives – formation of efflorescence, corrosion of reinforcement.
Additives that retard hardening are used in the main. When concreting massive structures to reduce heat generation in hardening concrete and, accordingly, temperature deformations. Hardening retarders – LST (technical ligno-sulfonate), NFT (nitrilotri-methyleneceosphonic acid), KP (fodder sugar syrup or molasses), etc. The use of hardening retarders may be accompanied by an increase in the strength of concrete at 28 days of age and later time of hardening, lengthening of the period beforehand, exposure before heat treatment.
One of the varieties of R.t.b.
Are antifreeze additives (PD), which are chemical? Additives intended. For concreting at low posit, and at neg. Temp-pax. Depending on the region. PD applications are divided into two groups: additives that reduce the freezing temperature of the liquid phase of concrete; additives from molasses supplier Malaysia combine the ability to strongly accelerate the setting and hardening of cement with good antifreeze properties.
Concrete hardening regulators are introduced into concrete in a quantity of 3-15% of the cement mass. The dosage value depends on the type of additive, ambient temperature and is in inverse proportion, depending on the latter.
Concrete hardening regulators are widely used in the construction of monolithic and precast-monolithic reinforced concrete. Structures and structures, including concreting in sliding formwork, when embedding joints in prefabricated structures, etc. They make it possible to conduct concreting at a temperature pax up to minus 30 ° C. The use of antifreeze additives is accompanied by an increase in the electrical conductivity of concrete, and a number of additives can cause corrosion of the reinforcement.
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