SU1648937A1 - Process for preparing industrial foam - Google Patents

Abstract

The invention relates to the building materials industry and can be used to produce lightweight concrete with porous cement stone. The purpose of the invention is to increase the resistance of the foam in the cement paste and concrete mix, reduce thermal conductivity and increase the frost resistance of concrete. The foaming solution containing the wood saponified resin and the stabilizer is whipped by circulation to obtain a foam with an average density of 310-360 kg / m3, then reduce air leaks by 50-90% and continue circulation of the foam for 20-60 seconds. The method does not require sophisticated technological equipment, is simple and allows to obtain concrete with improved physico-mechanical characteristics. Foam resistance coefficient in cement paste is 0.97-0.98, in concrete mix 3-5%, thermal conductivity 0.22-0.23 W / m ° C, coefficient of frost resistance of concrete per 100 cycles of alternate freezing and thawing 1. 1 tab. Yo

Description

The invention relates to the building materials industry and can be used to produce lightweight concrete with porous cement stone.

The purpose of the invention is to increase the resistance of the foam in the cement paste and concrete mix, reduce thermal conductivity and increase the frost resistance of concrete.

The high resistance of the foam in the cement paste and concrete mix is ensured by the optimum thickness of the cement-water casings around the air bubbles created in the concrete mix or cement paste with technical foam produced by this method.

The essence of the method is to provide a foam with an optimal structure and characteristics, with the introduction of which in the cement system

the latter is characterized by the optimum thickness of the cement-water casings and the diameter of the air bubbles. This is achieved by the fact that the foaming solution containing LMS and stabilizer is cut in a pneumatic foam generator to obtain a foam with an average density of 310-360 kg / m3, then the air leaks by 50-90% and the circulation of foam continues for 20-60 with.

When the optimal parameters of the method go beyond the limits, the thickness of the cement-water shells decreases or increases, which in the first case leads to the collapse of air bubbles or their aggregation (i.e., merging into larger ones), and in the second case - to sedimentation of particles nte and follow

N 00

about

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reduction of the structural strength of the shells. Due to the occurrence of these processes, the initial fine structure of the porous cement paste is destroyed, and part of the air is removed from the mixture to form large pores and cavities. As a result, the frost resistance of hardened concrete is reduced and its thermal conductivity increases.

The preparation of the technical foam to the fed process is as follows.

Prepare a working solution of wood saponified resin of 8-10% concentration and milk of lime of 8-10% concentration, which are mixed in a 1: 1 ratio by volume. The resulting foaming solution is supplied in the required amount to a pneumatic foam generator and beat by forced circulation through a closed cycle until the average density of the foam reaches 310-360 kg / m, then the air is reduced through the suction nozzle in the foam generator by reducing the cross section tubes using a valve or another method and continue to circulate the foam with the foam generator running for 20-60 s. The prepared technical foam is used to produce porous materials, for example lightweight concrete.

Example 1 An aqueous solution of a foaming agent was prepared consisting of an 8% aqueous solution of SDO and milk of lime 8% by concentration: it was fed to a pneumatic foam generator and whipped until the average density of the foam was 310 kg / m3, then, the air inflow through the suction nozzle was reduced by 90% and the foam circulation continued while the foam generator was running for 20 s. At the same time, a concrete mixture was prepared in the forced mixing mixer with the consumption of materials per 1 m ° of concrete: cement Resurrection M400-280 kg, expanded clay gravel bulk density 450 kg / m with a ratio of fractions 5-10 and 10-20 equal to 3: 7 1.1 m3, water 150 liters. The finished foam was introduced into a concrete mixer in the amount of 150 l and mixed with an unorhized mixture for 30 s. Samples of ceramisite foam concrete 15 x 15 x 15 cm in size were molded from the resulting mixture.

which were kept for 1.5 h and steamed in the 2.5 + 6 short-circuit mode at an isothermal heating temperature of 85 ° C.

PRI mme R 2. Solution frother

in Example 1, it was whipped in a foam generator until the average density of the foam was 330 kg / m, after which air leaks reduced sia 70% and carried out an additional circulation of foam for 40 s.

Example Frother solution

whisked to an average density of 360 kg / m3, then reduced air leaks by 50% and continued foam circulation for 60 s, Examples 4-9. Prepare technical foam with extreme values of method parameters. In these examples, the foaming agent solution, the composition of which is given in Example 1, was whipped until an average density of foam was obtained, respectively 300; 370; 330; 330 and 330 kg / m3, air leakage was reduced respectively by 70; 70; 40; 100; 70 and 70%, additional circulation of foam was carried out, respectively, for 40; 40; 40; 40; 10 and 70 s.

Test results are presented in

the table.

As can be seen from the above data, the coefficient of resistance of the foam obtained by the proposed solution in cement paste approaches 1 and equals 0.97-0.98, and by the known 0.85, i.e. much lower. The coefficient of resistance of the foam in the concrete mix, 2.4-4 times higher than that known. Thermal conductivity of concrete decreased from

0.32 W / m ° C to 0.22-0.23 W / m ° C, i.e. by 28–31%, and the frost resistance coefficient increased by 1.43 times. ,

Claims (1)

Claims The method of preparing a technical foam, including beating the circulation of a solution of a foaming agent containing wood saponified resin and a stabilizer, to obtain a foam of a given average density, characterized in that in order to increase foam resistance in cement paste and concrete mixture, decrease thermal conductivity and increase frost resistance of concrete, frother solution is whipped to obtain foam with average density of 310360 kg / m3, then reduce air leaks by 50-90% and continue foam circulation for 20-60 with.