SU1468887A1 - Method of preparing porous light concrete mix - Google Patents

Abstract

The invention relates to the construction of building materials and can be used for the manufacture of products from lightweight concrete based on large and small porous aggregates using foams of increased viscosity. the mixture consists in the fact that the cement is mixed with 10-45% of the calculated amount of water, the mixture is kept up to the partial pressure of water vapor before the end th znachesh JE further administered filler and blowing agent with the remaining amount of water and stirring was carried out again. The strength of concrete is 10.5-10.6 MPa, the density of 960-980 kg / m, the moisture content of concrete is 10-11%, 1 table. and

Description

one

The invention relates to building materials and may be used in the manufacture of concrete products based on large and small porous aggregates.

The purpose of the invention is to reduce the density while maintaining strength and reducing water absorption,

When cement is mixed with water, its chemical potential (partial pressure of water vapor) increases dramatically, which leads to an intensification of the process of mass transfer of moisture from the cement paste to the depth of the porous aggregate. B results in the mass of absorbed moisture in the porous aggregate of cement paste clean water over the same time period. In addition to TorOj, when mixing foam with cement paste, the water of which is characterized by volatile partial vapor pressure, foam resistance decreases. With low water-cement ratios (, 05-0.25), the surge time of the partial pressure of water vapor is 3-20 minutes, and with the secondary introduction of water into the concrete mix, the increase:.: Chemical potential of water (increase of partial pressure)

3,146

water vapor) is absent or the magnitude of the burst is 8-10 times less (for concrete mixes with primary, 05-0.1, i.e. during the initial injection.

10-25% of water). Taking into account this relationship, it is possible to reduce water absorption by a porous aggregate, to increase the resistance of the foam (that is, to reduce the density of the concrete) and to reduce the time beforehand. This is due to the introduction of a two-stage water injection combined with the operation to control the partial pressure of water vapor (water chemical potential gradient).

At the first stage, part of the water is mixed with cement, then the partial pressure of water vapor is measured, and when it is reduced, the resulting cement paste is mixed with the remaining components of the concrete mix and the remaining part of the water. This technological solution makes it possible to eliminate the hydrophobization of the porous aggregate with solutions of surfactants, slow down the hardening of concrete and the length of D9iX time of anti-aging during simultaneous reduction of water absorption of the porous aggregate compared to the method of hydrophobization.

The method of preparing a porous light concrete mixture is carried out as follows.

Cement is poured into a forced-action mixer, then water is poured into the mixer, the tel (10 and 5% of the calculated amount of water) is mixed for 40 s, the mixer is stopped and the water vapor pressure is measured.

dy When the water vapor pressure is reduced to the initial value, the remaining components of the concrete mix are loaded into the mixer: porous aggregate, foam and the rest of the water, are mixed for 40-80 seconds and the concrete mix is discharged from the mixer.

The method of preparing porous light concrete mix reduces the tempering humidity of the concrete by 8-10% by reducing the water absorption of the porous aggregate, reduces the density of the concrete by 100-150 kg / m by increasing the resistance of the foam in the concrete mix and shortens the time of pre-aging. heat treatment for 2.5 hours,

. The composition of light-weight concrete mixtures prepared by this method, and their physico-mechanical characteristics are shown in the table.

Claims (1)

Invention Formula The method of preparing porous light concrete mix, which includes mixing cement, aggregate, foaming agent and water, characterized in that, in order to reduce the density while maintaining strength and reduce water absorption, the cement is mixed with 10-45% of the calculated amount of water, to maintain the mixture until the partial pressure decreases water vapor to the original value, a filler and a porous agent are introduced with the remaining amount of water and re-mixed. Composition of concrete (consumption per 1 m) Cement, kg Expanded clay, m Foam, l Water, l Water / cement ratio Release moisture. concrete,% 0.8 0.8 0.8 14 ten ten 0.8 0.8 0.8 ten II 15 250 1.1 200 0.8 20 Water absorption of the porous aggregate to the beginning of the setting of the coefficient of resistance of the foam in the concrete mixture Pre-exposure time before heat treatment, h before re-mixing, min The density of concrete, kg / m Concrete strength kgf / cm: .Table continuation 10 0.89 1.5 1216 0.80 0.63 , 51.5 20 12,960 106 16,980 105 30 1100 102 FROM 108