SU967992A1 - Raw mix for preparing cellular concrete - Google Patents

Description

The chemically active additive potash also reacts with calcium hydroxide cement solution with the formation of a stronger base (potassium hydroxide), which raises the pH of the medium, contributes to the intensification of the gassing process, aluminum powder, entering into the reaction with calcium hydroxide and potassium emits free hydrogen, which porizes the concrete mix. Molasses interacts with cement minerals, forms insoluble salts (calcium sugars), which slow down cement hydration and at the same time plasticize the concrete mixture. Molasses is a waste formed during the manufacture of sugar from beets, and contains up to 10% amides, up to 50% sugars, 12% silicates and 28% water. As tests have shown, a potash content of less than 1% can cause a mixture to freeze, a potash content of more than 6% leads to a quick setting of the mixture, a decrease in strength and frost resistance of aerated concrete. The content of aluminum powder in the amount of less than 0.01% will not provide porosity of the mixture, and more than 0.06% leads to a decrease in the bulk mass and strength. The content of molasses in an amount of less than 0.015% does not exhibit a retarding and plasticizing effect on the concrete mix, and more than 0.1% slows hardening sharply and lowers the strength of the concrete. In tab. 1 shows the content of components in the mixtures. Table 1

The proposed mixture is prepared as follows.

Sand and an aqueous solution of potash and molasses additives are loaded into the forced action mixer. Mix it for 2 minutes, then load Portland cement, water and aluminum suspension, and mix the whole mass for 6-6.5 minutes.

The aluminum slurry is prepared from PAP-1 aluminum powder (GOST jS 5494-71) and a powder emulsion. Soap emulsion is used to remove grease film from surface particles.

powdered and prepared on the basis of

1 weight.h. Progress soap (TU38-1071977) for 10 weight parts. water.

Mixing and holding the samples was carried out at different temperatures.

Concrete samples obtained at 10 ° C (Table 2); -5С (tabl .: 3) and (tab. 4) are characterized by the following physicomechanical properties. At negative temperatures (s), the samples were kept for 7 days, and then up to 28 days mt, under normal conditions.

table 2

The degree of expansion of the mixture,%

The strength of concrete, MPa, after: 7 days,

28 days; Frost resistance, cycles

As can be seen from the table. 2-4, samples of aerated concrete can be made of the proposed mixture at a negative temperature and at the same time have sufficient strength and frost resistance.

In addition, the degree of expansion of the proposed mixture is on average 1015% higher than the degree of expansion of the known mixture.

The results of the tests confirmed the possibility of producing aerated concrete at low temperatures without heating. This will allow, even in the conditions of the construction site, in wintertime, to fill with a mold and carry out the installation of joints in large-panel buildings without mechanical impact.

The cost of 1m known mixture of 13 rubles. The cost of 1m of the proposed mixture (due to the introduction of molasses and potash instead of PRS and sodium sulfate) will be 16-20 rubles.

The expected savings from using the proposed mixture instead of the known will be 8-12 rubles. on 1 m (due to the exclusion of works related; with heating the material and heating the aerated concrete in the joints or forms, as well as by eliminating the capital expenditure. Continuation of table. 4

9.8 17.5

VIY for the purchase and installation of equipment for heating aerated concrete).

Claims (2)

1. Authors certificate of the USSR 481564, cl. From 04 To 13/22, 1973. 2. TsBNTI Mint zhstr of the USSR Intrusion of efficiency joints, M., 1978 (prototype).