DE1646616A1 - Process for the production of aerated concrete - Google Patents

Description

INTEHNATIONELIA SIPOEEX AB

Sveavägen 21

Stockholm / Sweden

Patent registration

Process for the production of aerated concrete

The invention relates to a method for producing Aerated concrete from a pourable mixture or mass prepared with water, which in addition to a hydraulic binder in the form of cement tind / or lime as well as finely divided, silica-rich aggregate, for example sand, also a gas-bubble-generating agent, preferably aluminum powder, and optionally stabilizing ones for this purpose Additives to promote an approximately uniform pore structure contains.

In the previously known method for producing aerated concrete the mixture is prepared with a relatively large amount of water added, so that they have the character of a for pouring into the mold

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has relatively light sludge. As a result of the internal gas bubble development, it swells or expands Mud, being to the extent that it is suitable for lightweight concrete typical pore structure during the preparatory stage of the chemical reaction of the binder present and of the silica-rich aggregate gradually develops becomes "dryer". The expanding mass solidifies progressively, but needs a relatively large amount Time until it has reached such a degree of rigidity that it can be further treated or further processed, for example cut into smaller pieces, and up to the mold can be removed at all.

It is in such a common 'aerated concrete production It is important that the mass during the expansion and immediately afterwards against disturbances in the form of vibrations, Impact or the like is protected, as otherwise the small gas bubbles that arise will combine in the mass to form larger bubbles, which rise to the surface and escape there, whereby the mass collapses again. This sensitivity of the mass in the production of aerated concrete means one considerable difficulty, especially the need to solidify the mass during a certain, not insignificant solidification time to let rest is a disruptive intervention. It is

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is therefore the task of producing aerated concrete in a way that shortens the setting time and a faster one
Insensitivity "of the mass can be ensured. At the same time, other disadvantages of the known methods are to be avoided, which can also be seen in the fact that the
just finished aerated concrete body have a relatively high moisture content due to the high water content of the original mixture.

To solve this problem, the invention consists in that the mass is prepared with such a small amount of water added that it has a viscous consistency that excludes or greatly restricts the possibility of the gas-bubble-forming agent.
bring about the expansion of the mass in the normal state, and
that the mass is subjected to such an action, preferably in the form of shaking or vibration processes, at the same time as it is formed into finished bodies, that the theological properties of the mass are thereby changed in such a way that the expansion is brought about by generating gas bubbles despite the low water content in the mass will. These shaking or vibration processes on the aerated concrete mass can expediently be brought about by intermittently recurring impacts or series of impacts that affect the mold or the container in which

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the mass is located during the expansion, and / or on in this Form or this container introduced auxiliary elements exercised be, which present the aerated concrete mass for transmitting the vibrations a large surface and out of contact with the Mass be brought before this. Solidifies.

When the invention is used, all are given in the first place Difficulties and disadvantages avoided due to high water addition or content both in the starting mixture as also in the expanding or solidifying mass and in the processed and finally hardened aerated concrete product are. At the same time, the mass becomes considerably less sensitive and, above all, hardens during the expansion the finished expanded mass significantly faster to such a consistency that the aerated concrete body is divided and processed can be. In addition, with reinforced aerated concrete bodies, increased adhesion of the reinforcement is achieved because the vibrations or vibrations a compression of the mass around the reinforcement creating around and inducing movements in the crowd creating a deteriorated bond between such parts of the crowd prevent that after the upward movement on both sides of a rebar meet again above this as a result of the expansion of the mass.

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To break the mass formed by the expanding mass To prevent aerated concrete body, it has to be applied the invention proved to be useful to choose the vibration frequency so that natural vibrations in the aerated concrete body formed, d. H. Resonance vibrations in it, to be avoided »In In some cases it is also advantageous to use the shaking or vibration frequency to change continuously or gradually to the extent that the aerated concrete mass "expands. the greatest possible reduction in viscosity achieved without that there is a risk that the aerated concrete body will break.

■ • It is easy to see that when applying the Invention the aerated concrete mass through, suitable additives or through an increased fine distribution and processing of their components adapt to the new procedure even further. Above all however, it is the reduced water content that enables to use the shaking or vibration method. ;

What results by using the method according to the invention can be achieved, was determined by the following testsί

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1) When preparing an aerated concrete mass with an otherwise common composition with finely ground quartz sand and cement as the main components and with aluminum powder as a gas-forming additive / the amount of water was reduced to 73-3 % of the otherwise usual water addition, whereby a viscous mass was obtained instead of a low-viscosity sludge. This mass was filled into a mold which was subjected to the pounding of a powerful, hand-operated impact hammer at a frequency of approximately 30 blows / minute. This shock vibration was applied for 10 minutes. In comparison with an aerated concrete product which was produced in the usual way without vibration from the same aerated concrete mass, but with the normal addition of water, the following values were obtained with regard to '=

a) the time in hours from pouring the mass into the Shape until it can be cut, d. H.

₌ the so-called solidification time;

b) the moisture content in% of the finished steam cured Product on removal from the autoclave;

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c) the compressive strength in kp / cm of the finished product after drying to a moisture content of 10 % _Λ and

d) the gross weight in kg / dm of the finished product.

at use when using the the invention known procedure 5.0 28 37

a) solidification time (h)

b) moisture content {%)

c) compressive strength kp / cm kB: kj,

d) Hardly weight kg / dnr 0.5 0.5

Particularly noteworthy are the significant reduction in the solidification time by approx. 30 % and the equally significant reduction in the moisture content, since these factors have an extremely favorable effect on the time for the production of the product and a considerable increase in capacity in systems that are already in operation by using the mean process according to the invention. The increase in compressive strength of the finished product by approx. 7 % is also obvious and of considerable importance. With regard to the volume weight, both products are the same.

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2) A gas concrete mass with that used in experiment 1) Composition with a water content reduced to 73 »3 5ό compared to the normal addition of water was used in poured a mold that was completely at rest until the mass had solidified. A recognizable one Expansion of the mass did not occur here, what the

= = / that

In conclusion, that aluminum powder is contained in the mass alone without the vibration effect according to the invention was not able to perform its task. ' When the solidified mass was broken up, only a small number of small and widely scattered pores could be found will.

3) When preparing an aerated concrete mass with the same composition as in experiment 1) for the production of an end product with a minimal weight of 0.5 kg / dm, the water content was reduced to ^ k % of the usual water content. The mass was poured into four identical molds, onto which were poured by mechanical vibrators

Vibrations with different frequencies and amplitudes each Exercised for 10 minutes from the moment of pouring became. The expanded mass was then allowed to solidify and then hardened in the usual manner in autoclaves. The result besü-fvüich de * - difference dw

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Compressive strength of the final product for -various The relationship between vibration frequency and amplitude is shown in the following table:

frequency
Vibrations / sec. amplitude
mm Crush resistance
kg / cm 12th 0.5 50 20th 0.2 > 7 Ί> Ί 0.15 45 50 0.1 46

The experiment shows that relatively large changes, especially with regard to the vibration frequency are conceivable without affecting the compressive strength of the end product is changed significantly, but that a low frequency with a relatively large amplitude is preferable.

4) the effect of the vibration method on aerated concrete masses to investigate with different types of binders ·! three kinds of masses were prepared - all adapted to the weight of the final product

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of 0.3 kg / dm - with cement or cement and slag and cement and lime as binders. and subjected to an amplitude of 0.5 ^ m. The solidified porous bodies were steam-cured in the usual manner, and the compressive strength in kg / cm was measured. In all compositions, the water addition was reduced to 72.5% of the normal water addition. As a control, three corresponding moldings were produced in the customary manner without vibration from the same masses but with normal water addition. The difference in compressive strength of the various products is shown in the following table:

Type of binder vibration

Without vibration

Compressive strength Compressive strength

kg / cm ^£

kg / cm *

cement

Cement and slag cement and lime

36

39

33

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Regardless of the type of binder, an increase in compressive strength in the order of magnitude of 9 % was achieved with the method according to the invention. The solidification time and the moisture content were increased by about 50 and kO% for all vibrated masses.

Claims

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Claims (1)

Pat ent a η s ρ r ü ehe M.J method for the production of aerated concrete from a with water prepared pourable mass, which in addition to a hydraulic binder in the form of cement and / or lime as well as finely divided, high-silica Additive, for example sand, also a gas-bubble-generating agent, preferably aluminum powder and this optionally contains stabilizing additives, characterized in that the mass is prepared with such a small amount of water added that it gets a viscous consistena that the possibility for the gas-bubble-forming agent excludes or greatly restricts bringing about the expansion of the mass in the normal state, /Dimensions
and that the body is subjected to such an action, preferably in the form of shaking or vibration processes, that the rheological properties of the mass are changed in such a way that the expansion of the aerated concrete mass by generating gas bubbles despite the low water content in the mass is brought about » 2. The method according to claim 1, characterized in that the Aerated concrete mass during shaping Shaking or vibration effects is subjected to intermittently recurring impacts or series of impacts. -13- 109829/1359 _ bad -.13 - 3. Method according to claim 1 or 2, characterized in that that the shaking or vibration effects on the aerated concrete mass about the mold or container in which the mass is vüfcer is located during the expansion, and / or in this form or this container introduced auxiliary elements are exercised, which present the aerated concrete mass for transmitting the vibrations a large M surface and are brought out of contact with the mass before this solidifies: k. Method according to one of the preceding claims, characterized in that the Büttel- or Vibrationfreijuenz is chosen so that natural vibrations in the body formed from the mass are avoided «; 5. The method according to any one of the preceding claims »M, that the shaking or vibration frequency is continuously or stepwise changed in the extent that the mass expands. The patent attorney OAO ORIGINAL