FI57225B - FOERFARANDE FOER FRAMSTAELLNING AV LAETTBETONGBYGGNADSENHETER SAERSKILT AV VAEGG- OCH TAKSTORLEK - Google Patents

Description

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Patent »och ragiatarstyralaan AiMMctn utlagd och utUkrtftan publicmd 31.03.80 (32) (33) (31) Privilege claimed — B« gird prloHtet (71) Micro Mineral Holding societe anonyme, l4 Rue Aldringer, Luxembourg, Luxembourg (LU) (72) Charles William Brabazon Urmston, London, England-England (GB) (74) Berggren Oy Ab (54) Method for the manufacture of lightweight concrete units, in particular wall and roof size units - Förfarande for framställning av lättbetongbyggnadsenheter särskilt av vägg- och takstorlek This invention relates to for the manufacture of either reinforced or non-reinforced concrete. In particular, the invention relates to a process for preparing these building units which comprises forming a dry mixture of aluminum powder, alkali, aeration catalyst and soap, introducing the mixture into water at a temperature of 35-75 ° C, forming a mixture of Portland cement and a fine filler and adding the above aqueous mixture. to the cement mixture immediately after the dry aluminum powder mixture is added to water, also using a coarse filler, this is added to the finished mixture after air formation in the mixture has begun, poured into the mold, partially sealed, and allowed to solidify in the mold under air formation pressure.

British Patent Publication 648,280 discloses a typical method for producing porous concrete.

British Patent 1,040,442, the inventor of which is the same as in the present application, describes a particularly advantageous method for producing lightweight concrete by means of aluminum. According to this patent, a dry mixture of aluminum powder, alkali 57225 and preferably an air-forming catalyst, and soap is formed, a mixture is added to water having a temperature in the range of 35-75 ° C, a mixture of Portland cement and fine filler is formed and said aqueous mixture is added to the dry mixture immediately thereafter. after the dry aluminum alloy has been added to the water, the mixture is poured into a mold, the mold is disassembled after the mixture has solidified and the unit obtained is preferably treated in an autoclave. Coarse filler can be advantageously used in this method. The coarse aggregate is added to the mixture of Portland cement and fine aggregate.

In all previously known methods for producing lightweight concrete using aluminum powder, it has been a disadvantage that units higher than a certain height could not be produced without the concrete solidifying unevenly with the result that it is unusable.

The object of the present invention is to enable the casting of units of layer height.

This is done by said previously known method, in which the mold is closed after the mold has been filled with the mixture so that there is room for expansion, and the mixture is allowed to solidify in the mold under the influence of the pressure generated by air formation. To achieve said purpose, the known method is improved in that it is characterized in that the mold is closed by a torn rigid lid which covers the entire surface of the top of the mold and includes a filter device below the lid so as to allow gas and liquid but no solids to escape.

Swedish patent 73924 discloses a method for producing lightweight concrete, in which a lid is placed on the mold after the mixture has been poured into the mold, whereby the gases create a pressure which causes the concrete walls to compress. This is said to provide greater strength after curing. The mold cover may have grooves or channels that allow gases to escape around the edges of the mold.

However, if air is allowed to escape from the edges of the deck, blow holes may occur at the points where the air passes before exiting. If the transfer of solids is not prevented in any way, they will escape to some extent along the channels. Thus, the final density is uncertain and varies throughout the unit. Solids that exit along the channels from the edges of the lid harden and tend to lock the lid to the bottom of the mold or render it unsuitable for re-use.

57225

When the perforated lid according to the present invention covers the entire surface of the top of the mold and there is filter paper below it, these disadvantages are avoided and the following advantages are obtained: a) the concrete hardens under a pressure that can be resisted by an economically structured mold; achieving a homogeneous quality over the entire height, c) this allows the use of significantly higher molds and unit height units, d) gas can escape to reduce the pressure and as it exits the entire surface avoids blowing holes, and e) the mold retains the entire original amount of solids, so the density, strength and other properties of the unit can be determined in advance.

The treatment of lightweight concrete units in an autoclave is not new per se, it is known, for example, from Finnish patent 21219. American patent 2 770 864 proposes the use of torn lids, but according to this patent the solids were to penetrate the holes. This would not be suitable for the manufacture of building units, as the density of the unit could then not be determined in advance. None of the prior art discloses the fabrication of floor-height units.

Preferably, the mixture is prepared by first introducing into the mixture water having a predetermined temperature, which may be in the range of 35-75 ° C and most preferably about 65 ° C, an "activating agent" consisting of the type of aluminum powder known as "atomized", together with alkali and catalyst and soap in predetermined amounts. The atomized aluminum powder is preferably of the order of magnitude known as "120 dust" and is sold by Alcan Industries Limited. The reaction between aluminum and alkali begins as soon as the activator comes into contact with water. The water is then immediately introduced into the fine aggregate and cement in a mixer. If no coarse aggregate is required, then the mixture is placed in a mold when the reaction is sufficiently advanced.

57225 Μ

If a coarse aggregate is required, it is placed in the mixture in a mixer about one or one and a half minutes after the addition of water, after the mixture has been brought into a state sufficient to support the coarse aggregate with respect to air formation. Stirring is continued only until homogeneity is obtained and the mixture is immediately placed in a mold. The size of the coarse aggregate can be 19.05 mm to 6.35 mm and the bulk density can be 960 kg / m 2, although higher bulk weights can also be used if the size is reduced.

With the preferred method according to the invention, the molds can be filled to a considerable height, e.g. 2.45 m or more, without any significant disturbance in homogeneity being observed. The full height of the piece can be used. A suitable type of coarse aggregate can be used without separation. Reinforcement can be used without forming a “shadow”.

A surprising advantage of the method is that good results can be obtained by using pumice as a aggregate, either as a fine or coarse aggregate or both. Pumice is a low-density material that occurs in nature in enormous and readily available quantities. Pumice has so far not been used in high quality aerated concrete, and this is largely due to its relatively high water absorption and variable composition. In the process of the present invention, these properties have not been found to have any significant detrimental effects on the product.

The volume volume of the pumice mill used in the application of the invention may vary in the range from 160 kg / nr to 560 kg / m 2. Pumice can form part of a mixture of fine aggregate or all of the fine aggregate and also part of the coarse aggregate or all of the coarse aggregate, if used.

The part which is made in the mold according to the invention can be used as it is or it can be cut into e.g. sheets. Previous methods of making aerated concrete have included making a head piece that is cut into sheets with multiple yarns after the material has expanded and cured in an autoclave treatment. Previously known methods (with the exception of the method of British Patent Publication 1,040,442) could not use a coarse filler and the shearing effect was comparable to that of cheese. This method of cutting would not work with coarse aggregate because the yarns would tend to take 5,572,225 larger particles through the material. For this reason, the body is sawn after autoclaving, when coarse aggregate is used in the method according to the invention and the body has to be divided. Since in the method according to the invention the body can be manufactured to a much higher height than before, it will often be possible to form the body for use as such instead of dividing it into parts as has hitherto been customary.

The following are various examples of mixtures for use in the practice of the invention. The activation agent mentioned in the examples is in all cases a dry powder mixture formed as follows: atomized aluminum powder (commercially available under the name "120 dust", sold by Alcan Industrie Limited) sodium carbonate sodium stearate ferric oxide

In all examples, the coarse aggregate screening curve is essentially as follows:

Screen size% throughput 19.05 100 15.88 90 12.70 20 9.55 10 6.35 5 No. 7 traces "Leea" and "Aglite" are trademarks of commercially available sintered clay aggregates, the former weighing approximately 400 kg / m 2 and the latter has a bulk density of 544 kg / m 2 The pumice stone, when used as a coarse aggregate, is crushed to a nominal size of 9 to 55 mm, leaving about 80% on a 12.70 mm screen, and has a bulk density of 384 448 kg / m 2.

"Ash" is fly ash formed from the remnants of ground coal after combustion, e.g. to generate electricity.

The cement is ordinary fast-curing Portland cement, (although the cement, cut proposed in British Patent Publication No. 1,090, may be "mieron sized" by a reduction in the amount mentioned in said patent publication).

In the examples, the cured volume and density belong to the full mold. There will be no waste.

Example 1

Ingredients Quantities

Cement 98.96 kg 57225

Ash 163.30 kg

Aglite 170.10 kg

Activating agent 960 g

Water, 65 ° C 131.83 L

The mixing time was 4.3 minutes and the cured volume was 0.3 g <: 7 3 nr. The density of the product was 1120 kg / m 2.

Example 2

Ingredients Quantities

Cement 98.96 kg

Ash 163.30 kg

Aglite 158.76 kg

Activating agent 1450 g

Water, 60 ° C 186.38 1

The mixing time was 4.3 minutes and the cured volume was 0.538 m 2. The density of the product was 800 kg / m 2.

Example 3

Ingredients Quantities

Cement 98.96 kg

Ash 86.99 kg

Sand 75.30 kg

Aglite 158.76 kg

Activating agent 960 g

Water, 60 ° C 131.83 L

The mixing time was 4.0 minutes and the cured volume was 0.382 3 3 irr. The density of the product was 1120 kg / nr.

Example 4

Ingredients Quantities

Cement 76.20 kg

Ash 152.41 kg

Leea 191.42 kg

Activating agent 900 g

Water, 65 ° C 186.38 1

The mixing time was 4 minutes and the cured volume was 0.536 m 2. The density of the product was 800 kg / m 2.

Example 5

Ingredients Quantities

Cement 98.96 kg

Ash 163.30 kg 7 57225

Leea 127.01 kg

Activating agent 1000 g

Water, 68 ° C 177.29 1

The mixing time was 4 minutes and the cured volume was 0.498 nr5. The density of the product was 800 kg / m 2.

Example 6

Ingredients Quantities

Cement 98.96 kg

Ash 86.99 kg

Sand 75.30 kg

Leea 99.79 kg

Activating agent 700 g

Water, 62 ° 131.83 1

The mixing time was 4.5 minutes and the cured volume was 0.331 m 2. The density of the product was 1120 kg / m 2.

Example 7

Ingredients Quantities

Cement 76.20 kg

Sand 152.41 kg

Leea 127.01 kg

Activating agent 900 g

Water, 65 ° C 135.92 L

The mixing time was 3.5 minutes and the cured volume was 0.495 m 2. The density of the product was 848 kg / m 2.

Example 8

Ingredients Quantities

Cement 76.20 kg

Ash 152.41 kg

Pumice stone (coarse aggregate) 127.01 kg

Activating agent 900 g

Water, 65 ° C 186.38 1

The mixing time was 4 minutes and the cured volume was 0.536 m 2. The density of the product was 800 kg / m 2.

Example 9

Ingredients Quantities

Cement 98.96 kg

Ash 163.30 kg

Pumice stone (coarse aggregate) 127.01 kg

Activating agent 1000 g

Water, 69 ° C 177.29 1 8 57225

The mixing time was 4 minutes and the cured volume was 0.498 m 2. The density of the product was 800 kg / m 2.

Example 10

Ingredients Quantities

Cement 98.96 kg

Pumice dust 136.08 kg

Pumice stone (coarse aggregate) 127.01 kg

Activating agent 1000 g

Water, 68 ° C 190.93 L

The mixing time was 4 minutes and the cured volume was 0.467 m 2. The density of the product was 784 kg / m 2.

Example 11

Ingredients Quantities

Cement 98.96 kg

Pumice dust 152.41 kg

Pumice stone (coarse aggregate) 99> 79 kg

Activating agent 150 g

Water, 67 ° C 136.38 1

The mixing time was 4 minutes and the cured volume was 0.322 m 2. The density of the product was 1120 kg / m 2.

Example 12

Ingredients Quantities

Cement 98.96 kg

Sand 163.30 kg

Pumice stone 99.79 kg

Activating agent 1000 g

Water, 66 ° C 218.21 1

The mixing time was 4.1 minutes and the cured volume was 0.453 m '*. The density of the product was 816 kg / m 2.

Normally, when the mixture is poured into open molds, the pouring of the mixture into the mold is stopped to adjust the pressure that develops at the appropriate pressure for the mold height given to the mold when the mixture is at a special distance from the top of the mold. The lid is then immediately placed on top of the mold tightly enough to prevent the concrete from coming out but so that the enclosed air can escape as the concrete expands.

It may be sufficient to simply screw the lid onto the mold without fitting a gas or water seal, but most preferably the lid consists of perforated plates of wood, metal or plastic and is provided with holes of the order of 6.35 mm x 19> 05 mm 9 57225 , in which case filter paper or some other semi-porous material is placed on the lid. These measures make it possible to allow the escaping gas or water to escape from the mixture so that (a) the mold does not break and (b) the maximum amount of water comes out through the filter means through holes in the supporting mold cover, which greatly degrades the product properties. If desired, other parts of the mold in addition to the lid may be torn.

Removing excess water is very important for the following reason. It is known that the water-cement ratio is critical in all concrete work. In order for the mixture to flow properly, a given amount of water must be used both in concretes of normal density and especially in blown concrete, including blown concrete containing lightweight aggregate according to the present invention. The minimum amount of water for suitable fluidity of the mixture is greater than the absolute amount of water required for hydrogenation. It is known in the industry that, especially in the production of solid concrete slabs (e.g. paving stones), it is possible to remove this excess water by using a very high pressure in the press, which increases the density of the concrete. In this preferred embodiment of the invention, a portion of the excess water is removed from the concrete at a pressure that develops when air is blown into it without increasing the density.

The concrete expands in the mold based on the effect of the reaction of the aluminum powder until the mold is full. This happens much earlier in time than the expansion would have stopped if the mold had been open. This final expansion stops due to the strength of the mold so that the entire mass is pressurized. The magnitude of the pressure is determined taking into account the desired final density of the material and the height to which the material is cast. The time of pouring or pouring of the mixture (i.e., the amount of air that is continuously remaining), the depth to which the concrete is poured, and the arrangement used to remove gas and air are determined experimentally.

The choice of aluminum powder and other chemicals as well as the temperature used in the process is such as to allow very rapid expansion in the mixer to allow support of the aggregate and also to allow a proportion of the total expansion to be filled before the mixture can be filled. to a greater extent than hitherto has been possible in known lightweight concrete production methods. The final expansion then develops pressure in the mold and this continues for longer than usual with prior art open molds so that the pressure remains in the mold until the material has hardened, and this improves bonding or adhesion between the material and any reinforcing steels as well as fine material and coarse aggregate. Without this final expansion, the material would tend to detach from the lid.

If this happens to some extent, the product will be considered unusable.

In a preferred embodiment of the invention described above, concrete is poured from above into molds which are then sealed.

If desired, the concrete can be pumped into a closed mold, e.g. from the bottom, in a manner similar to how plastic is injected into the spray mold.

An example of a mold used in applying the method is shown in the accompanying schematic drawing, in which Figure 1 shows a perspective view of the top of the mold, Figure 2 shows a section of a part of the mold cover and shows certain parts from below, and Figure 3 shows a plan view of the cover part.

For reference now, the mold assembled in the drawing comprises vertical sides 1, 2 and ends 3 »4 and removed vertical partitions 5 ·

The mold also has a base part not shown. All these parts are perforated.

The mold has a lid, generally indicated by reference numeral 6, comprising a row of parallel strip-like portions 7 with turned-up edges 8 fixed side by side by bolts 9 and reinforced by two strip-like portions 10 transversely over the top, which portions 10 are fixed by bolts 11. The strip-like parts 7, 10 in the example shown are standard type cable plates, but if desired, a specially made unit cover can be used. The parts 7 have holes of varying sizes from slots 14 measuring 6.35 x 19.05 mm and ends oval to round holes 15 with a diameter of 6.35 mm, which holes are arranged as shown in Fig. 3. The size and placement of the holes can vary widely.

Once the mold has been assembled except for the lid 6, the mixture is poured into different spaces 16 between the partition walls 5 until the mixture comes close to the top. The distance below the upper edge, i.e. the point at which pouring is stopped, is determined for the conditions given by the experiments. For example, in a mold 2.74 m high, pouring can be stopped 57225 15.2 cm from the top. In a very flat mold with a height of about 15.2 crt, pouring can be stopped 2.5 cm from the top. The top of the void should be larger for deeper molds but this need not be relative. The distance will also depend on the density that is to be given to the concrete, with lighter concrete releasing more gas.

The filter paper 20 is placed above the mold, on which the lid 6 is firmly tensioned, for example by means of lugs 21 located in the end walls 5, **, and by means of closing hooks 22 located in the reinforcing parts 10. Different types of filter papers can be used. The required strength depends on the magnitude of the pressure developed, p which can rise to 0.7 kg / cm, and the size of the holes in the lid.

If the holes in the lid are small enough, e.g. about 1 mm in diameter, then very little solid material will pass through, even if no filter paper is used.

Once the concrete has stiffened, the cover is removed, after which the piece is lifted out or otherwise removed. Each partition wall between adjacent pieces can be lifted off separately after the pressure has been removed from the end walls and side walls.

The method described has the following advantages: (a) since concrete can be homogeneous up to heights of 3,05 m, large unit panels can be produced which, if they have generally been possible to date, have had to be made from a number of individual "planks" which are: had to be joined together.

(b) normal blown concrete has considerable technical difficulties and high skill is required to obtain a constant density so that a homogeneous material can be produced even in molds up to a depth of 0.6 l. It is necessary to remove several cm from the top of the cast material after has stiffened. The method just described also improves homogeneity to a very large depth and avoids the need to cut off the top of the cast material.

c) the known weight of material is placed in the mold, no loss is made and the final density of the material can be completely determined in advance.

(d) vibration is unnecessary: the pressure in the mass seals the material tightly around any reinforcing steels that may be used, gives a good bond to the steel reinforcement as opposed to ordinary lightweight concrete with added air when expansion around the steel causes it to have a shadow effect, i.e. release between the top of the reinforcing steel and the material, which severely reduces the strength of the adhesion of the material to any reinforcing steel. Condensation of the material around the reinforcing bars also helps prevent corrosion of the steel.

(e) pressurizing the concrete as it stiffens not only increases the adhesive strength between the material and any steel reinforcement, but has the same effect in sealing the material in and around the lightweight aggregate, which * seeks to improve the physical properties of the concrete. If it is still desirable to profile or mold the model into the unit for decorative or other purposes, the expansion will help to achieve a clean-edged and accurate result due to the pressure.

Claims (4)

57225 13 1. A process for the production of lightweight concrete, especially wall and ceiling size building units, which comprises forming a dry mixture of aluminum powder, alkali, aeration catalyst and soap, introducing the mixture into water at a temperature of 35-75 ° C, forming a mixture of Portland cement and fine aggregate and the above-mentioned aqueous mixture, wherein the aqueous mixture is added to the cement mixture immediately after the dry aluminum powder mixture is added to water, also when a coarse filler is added to the finished mixture after air formation in the mixture in the mold at the pressure of air formation, characterized in that a) the mold is as high as the building layer, b) that the mixture is introduced into the mold when air formation has started, c) that the mold is closed by placing a perforated rigid cover on the entire surface of the mold and bestow tin material under the lid, allowing the removal of gas and liquid but not solids, and d) that the mold is disassembled when the mixture has solidified and the unit obtained is treated in an autoclave to cure it. A mold for carrying out the method according to claim 1, characterized in that the mold is an assembled mold with removable vertical partitions to form a plurality of units. 1. For use in the manufacture of carbon monoxide, for example, for the bleaching of aluminum powders, alkali, catalysts for the treatment of porous circuits, such as bleaching at 35 ° C, ° C, pictures and blends of portland cement and finishing materials as well as of these woolen blanks, colors of woolen blanks for concrete blasting after the application of aluminum powders to the wools, for example, for the manufacture of woolen fills the porous ring in the form of a blister, the shape of the formulation in the form, the shape of the shape and the shape of the form in the form of a porous ring,