SU1653964A1 - Method for molding concrete structures - Google Patents

Abstract

This invention relates to the molding of concrete products from rigid concrete mixtures. The purpose of the invention is to improve the physical and mechanical properties of concrete. When molding concrete products after placing the concrete mixture into its shape, it is compacted with vibration first with a frequency of 20–30 Hz and an amplitude of 1.1–2.5 mm for 5–7 s. then with a frequency of 45-60 Hz and an amplitude of 0.35-0.6 mm with simultaneous application of a uniformly increasing pressure first to 0.07-0.08 MPa for 3-4 s and then constant pressure for 20-25 s . 2 tab. yo

Description

This invention relates to the field of Forming concrete products from rigid concrete mixtures.

The purpose of the invention is to improve the physical and mechanical properties of concrete.

When molding concrete products after placing the concrete mixture in its form, it is compacted with vibration first with a frequency of 20-30 Hz and an amplitude of 1.1-2.5 mm for 5-7 s, then with a frequency of 45-60 Hz and an amplitude of 0.35 -0.6 mm and at the same time applying at the beginning a uniformly increasing pressure up to 0.07-0.08 MPa for 3-4 s and then constant pressure for 20-25 s.

Preliminary preparation of concrete grains at low frequency and high amplitude makes it possible to remove a significant portion of air from the mixture. A smoothly applied vibropressing pressure at an increased frequency allows the mixture to be compacted, bringing the particles closer together and liquefying the cement paste.

PRI me R 1. In a form rigidly mounted on an electrodynamic stand load fine-grained rigid concrete mix. Include the vibration exciter and vibrate the mixture at a frequency of 25 Hz and an amplitude of 1.8 mm 7 s. A pressing pressure is applied for 3-4 seconds to reach the steady-state regime with a frequency of 50 Hz, amplitude 0.6-0.35 mm, pressure 0.08 MPa. In this mode, the mixture is compressed for 26 seconds. Disable vibration compaction, relieve pressure.

Samples were made under standard conditions and tested at 28 day old.

Use cement Portland brand 500.

The accepted composition of the concrete mixture C is 450 kg. P-1800kg. In 170l.

PRI mme R 2. The concrete mixture of the composition of example 1 is loaded into the form. Compact: in the first stage, vibrate at a frequency of 20 Hz. 2.5 mm amplitude for 5 s, then at Os

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put the pressing pressure for 4 s, reaching a value of 0.07 MPa, in this case they enter the vibration mode with a frequency of 60 Hz and an amplitude of 0.35 mm, after 20 s the seal is completed, the vibrating device is turned off and the pressure is released.

PRI me R 3. The concrete mixture according to example 1 is placed in the form. The vibrations are carried out in stages: first, they vibrate with a frequency of 30 Hz and an amplitude of 1.1 mm for 7 seconds, then a pressure of 0.08 MPa increasing evenly for 3 seconds is applied, while entering a vibration mode with a frequency of 45 Hz and 0.6 mm amplitude. After 25 seconds the seal is completed. Turn off the vibration device and relieve pressure.

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Examples of the method and test results are presented in tabs, 1 and 2.

Claims (1)

The invention of the method of forming concrete products, including laying concrete-mixture into a form, the impact of vibration, followed by the simultaneous application of increasing pressing pressure, is different from the fact that, in order to improve the physico-mechanical properties of concrete, the vibration is first carried out with a frequency of 20-30 Hz and an amplitude of 1.1-2.5 mm for 5-7 seconds, and then with a frequency of 45-60 Hz and an amplitude of 0.35-0.6 mm with the application of a uniformly increasing pressure to 0.07-0.08 MPa for 3-4 seconds and then constant pressure for 20-25 seconds. Table 1 table 2