Vibrational Moulding of Products
The vibrational moulding of products is carried out in the moulds on a vibration table being manufactured according to the design drawings.
The dimensions of a vibration table are 1500 x 1200 mm with ИB (96:104) series electric vibration motor outfitted with adjustable eccentrics to select the amplitude.
The residence time of a mould on the vibration table ranges from 1.5 to 2 minutes until
the white liquid (“milk”) appears on the surface of mixture.
Mode of Product Hardening
The moulds having undergone a process of vibration are transferred to the hardening racks and stay there for forty-eight hours (the product hardening time depends upon the temperature and additives admixed to the concrete; it may be reduced to twelve hours).
After that a slab is removed from the mould.
The slab is removed from the mould via a hot water.
The temperature of bath water shall fall in the range of 45 to 50 °C.
The water is permanently heated with tubular electric heating elements. The slabs in
the moulds are stacked up in a hot water bath on top of one another until the full bath filling.
The minimum residence time of moulds with slabs in the bath shall fall in the range of 3 to
5 minutes until full heating of the mould.
Then a slab easily comes out of the mould with the help of knockdown device being stockpiled.
The products are air-hardened in the bottom plates in the shop room. In hot weather
the products must be moistened several times a day. In cold season the products must be stored indoors at the air temperature not below than 15 °C.
The slabs shall be shipped to the Customer when the products reach 90 percent of
the concrete grade on compression strength and the concrete grade on tensile strength in bending in cold season of the year having reached 70 percent in warm season of the year.
The 90-percent strength of this concrete composition is reached after 10 or 11 days of hardening while the strength equaling to 70 percent of the design one is reached after 3 or 4 dais and may slightly vary in dependence to the hardening conditions and the quality of cement.