SU933657A1 - Process for making concrete and reinforced concrete products - Google Patents

Description

I

This invention relates to a process for the production of concrete and reinforced concrete products.

A known method of manufacturing concrete and concrete products, in which, during their heat treatment, re-vibration is performed when the maximum internal stresses in the concrete are reached and is completed when they reach their minimum tl.

The disadvantage of this method is the discrepancy between the maximum of the internal eg; time of optimal application of repeated vibrations determined by the end of the period of formation of the coagulation structure of concrete, since the maximum stress is associated with the destruction of the initial hydroaluminate structure by subsequent products of hydration.

The closest to the invention is a method of manufacturing concrete

And concrete products, including the laying of the concrete mix in the form, compaction of its vibrating, heat treatment and re-vibrating in the process of the latter. Repeated vibrations are carried out after the concrete reaches a maximum of electrical conductivity 2.

This method does not accurately determine the moment of application of the second vibration effect, since the conductivity curve varies smoothly, and the maximum conductivity, depending on the achievement of the saturated state of the liquid phase, is significantly ahead of the end of the period of formation of the coagulation structure. The subsequent decrease in electrical conductivity occurs extremely smoothly due to the very slow chemical

20 water binding and can be observed much later than the end of the period of formation of the coagulation structure. All this does not allow to receive

concrete products with high strength and density.

The purpose of the invention is to increase the strength and density of concrete.

The goal is achieved by the fact that according to the method of manufacturing concrete and reinforced concrete products, including laying the concrete mixture into a mold, compacting it by vibrating heat treatment and repeated vibration during the latter, the potential for mass transfer of the concrete mixture is measured during heat treatment, and repeated vibration carried out 5-15 minutes after the maximum value is reached.

The method is carried out as follows.

The concrete mixture is placed in the form, vibrates, 2o electrodes are installed according to the direction of the mass flow at the surface or in another area of the product, they are connected to a self-recording milliliter voltmeter with high-resistance input, the change in the mass-energy transfer potential is recorded through 5 15 min after the device registers a peak corresponding to the moment when the formation of the coagulation structure of the concrete Q is finished and the hardening of it begins: it vibrates again for an optimum duration (0.5-5 in).

The sharp increase and decrease in the mass-energy transfer potential (peak) is due to the appearance of particles of a tobermorite hydrosilicate gel with a highly developed surface due to the small size of these particles (15-ZOA), as well as the subsequent compaction of the gel due to an increase in the concentration of these particles, causing a sharp reducing the permeability of the gel.

P r and m er. The drawing shows a graph of the change in electrical conductivity (curve E) and the potential of mass-energy-transfer (curve E) during the heat treatment of concrete.

Cubes of 10 10x10 cm are molded from concrete of grade 200 on portland cement of mark 00 by vibro-compacting the concrete mixture into forms. Samples are steamed in a mode with a sharp rise in temperature (unregulated rise) and isothermal exposure at 82 ° C. Repeated vibration exposure is applied at different time intervals from the beginning of the steaming, corresponding to the maximum electrical conductivity of the concrete and the maximum (peak) of the mass-energy transfer potential (points 1 of curve a, 2, 3, V and 5 of curve).

The table shows the test results of concrete.

Strength

The time of application of repeated vibrations after 80 minutes corresponds to the maximum electrical conductivity of concrete - point 1 on curve e, and 130 minutes - 10 minutes after reaching the maximum (peak) mass-transfer potential - point 3 of curve E.

The table shows that the optimal time for re-vibrating

Claims (1)

Claim A method of manufacturing concrete and reinforced concrete products, including 933657 6 laying the concrete mixture in a mold, compacting it with vibrations, heat treatment and re-vibrating in the process of the latter, I distinguish 5 with the fact that, in order to increase the strength and density of concrete, in the process of heat treatment the mass-transfer potential of the concrete mixture is measured, and re-vibrating C is carried out after 5 ^_ 15 minutes after reaching its maximum value.