DE1018350B - Process for the production of porous masses, especially for construction elements - Google Patents

Description

Process for the production of porous masses, in particular for construction elements The present invention relates to a method for producing hydraulically setting porous masses and moldings made therefrom, which are essentially mineral Fillers and hydraulic binders are made up and produced by gases or gases Substances are driven.

It is already known to obtain such masses or moldings in such a way that that a pourable paste or slurry is produced, in which it can be burned out, Brings vaporizable or gas-evolving substances, pours the mass in molds and then left to the driving process and the subsequent setting. One is however so far always based on the idea of maintaining a liquid consistency to offer as little resistance as possible to the development of gas in the mass, in order to achieve a complete formation of a bubble structure before the binding agent sets to get. In this way you have always had large amounts of water in the masses have to bring in and was dependent on the excess water by lengthy Dry to remove from the finished body after setting. Such high Initial water contents have a very detrimental effect on shrinkage, among other things or the duration of the shrinkage of the porous bodies produced by the known method.

It has now been found that the one with the hitherto indispensable Maintained high water content of the masses associated difficulties and disadvantages can surely overcome and turn off when the amount of water in the deformable and the starting mixtures to be driven is so low that the masses of are not pourable from the outset, but at least the consistency of a very have stiff, non-flowable pulps. The masses are of particular advantage. with regard to the addition of water even delivered in such a way that it only contains a crumbly, have earth-moist consistency. According to the invention, masses prepared in this way are then an intensive work-through, e.g. B. by mixing kneading, kneading or milling, subjected, then driven by gas evolution and depending on the type of binder used Brought to the setting without or with after-treatment.

The masses to be processed by the process according to the invention consist essentially of mineral fillers and binding materials as well those substances that enable gas to be released in the mass. As a mineral Fillers are mainly used for quartz powder and sands of various origins and grain sizes or blast furnace slag and the like. Also the use of fly ash, granular pumice - of natural or artificial origin - and other absorbent materials is possible. The well-known hydraulic binders are used to bind these fillers into consideration, especially cements of various types, lime, mixtures of cement and Lime or gypsum.

The mixtures of filler and binder are according to the invention dressed with amounts of water that are at least 20% less than those for Achieving a pourable mass. According to the preferred embodiment of the invention Procedure, amounts of water are chosen that are only 35 and even only 50% of those amount to achieve a conversion of the mass into a pourable consistency would be necessary.

The use of water in the specified amounts creates from the mixture of binder and filler, at least one that is barely plastic Porridge, generally even a short one; crumbly mass. The consistency of these masses would not enable them to hold the gases developed during the propulsion process and . the creation of a highly porous, stable structure required for lightweight bodies to make impossible. However, according to the invention, these mixtures are subjected to a mechanical processing in mixer kneaders .; Pan mills or compulsory mixers, in this way, despite the small amount of water available, you get a floating water Consistency, d. That is, they can after the addition of gas-evolving substances without further mechanical working through is carried out only by simple mixing stable bubble structure with optimal gas yield 'form and while maintaining this Structure setting. The duration of the mechanical working through, which is essentially consists in a kneading, mixing kneading or milling and expediently in a so-called Compulsory mixer is made, -depends on the type of for this Purpose used device and is for example 2 to 50, preferably 4 to 15 minutes. Although fine-grained in the previously usual way of working Masses required particularly high water surcharges and due to the intensive kneading after the new process some destruction (the structure of the components under further division can occur, it has surprisingly been shown that the masses treated according to the invention despite the small addition of water during driving do not tear off and keep the evolved gases well enclosed.

The drifting can be brought about by substances that are known per se will. For example, metal powders such as zinc or aluminum can be used form hydrogen under the influence of water or alkalis. Also solved Per compounds, which decompose with evolution of oxygen, come into consideration. Hydrogen peroxide is used as a propellant with particular advantage because it is light is to be mixed in homogeneously and is large without disturbing residue Gas quantities decomposed; especially if suitable decomposition accelerators are added will. To regulate the bubble structure and size and to increase the bubble stability The known means, such as soap solutions, glue solutions and the like, can be used will.

A particular advantage of the method according to the invention is that that the control of the bubble size also through the selection of the additives in 'appropriate Granulations can be effected. It has been shown that the bubble structure is so The finer the mineral fillers are, the finer it can be adjusted. For example result with otherwise the same mixture composition from river sand with one grain Mixtures produced from 0 to 0.5 mm after driving and setting moldings with an average pore size of over 1 mm. On the other hand becomes the river sand replaced by quartz powder, 90% of which passes through a sieve with a mesh size of 0.04 mm, the average pore diameter is well below 1 mm. Mixtures of Quartz flour and river sand in a ratio of 1: 1 lead to bodies with average Pore sizes of about 1 mm.

As a result of the small amounts of water to be used according to the invention when using inherently porous aggregates such. B. from fly ash or granular pumice, inasmuch as a substantial simplification, as such substances can be used immediately in the moist state, optionally without or mixing more water must be added, as the required water through the damp porous fillers is introduced into the mixture.

As already mentioned, the gas blowing takes place after the mixture kneading performed. The time at which the gas-evolving substances are added depends on theirs Decomposition rate dependent: So can gas-evolving substances that very react slowly, the mixture already before the start of the mechanical work-through can be added. This procedure is particularly suitable for aluminum powder. The powder is then distributed largely evenly during the kneading of the mixture, so that additional measures for mixing in are not required is. Substances that react a little more quickly can be used in the course of or towards the end of the work-through can be added. In these cases, too, the kneading process takes over the incorporation and the even mixing in of the gas-evolving substance. But for fabrics in which the development of gas begins particularly rapidly, the mixing must be carried out an additional work step following the intensive mechanical kneading be carried out, and in this case a careful stirring in takes place of the substance into the mixture, with an additional kneading completely or largely is avoided.

A particularly advantageous way of carrying out the method of the application with regard to the properties of the porous masses produced when the mixture is kneaded and after the addition of the blowing agent at least during the driving process, possibly also after it, Exposed to vibrations of any kind that cause the during of the blowing process forming gas bubbles periodically and as suddenly as possible be compressed and expanded.

There are many ways to achieve this goal, e.g. B. by one is the mass or the form containing it of the action of any mechanical or subject to acoustic vibrations. It is particularly advantageous to work by vibrating movements are exerted on the form or the mass, with the direction of movement expediently coincide approximately with the direction of the developing gas bubbles should, .d. i.e., it is appropriate. .to direct the shaking movement so that the vibrations are substantially perpendicular to the bottom of the container, since the gas bubbles the Have a tendency to rise in bulk while drifting. As very suitable for carrying out the advantageous embodiment of the method according to the invention has proven to be a so-called upsetting movement, which consists in that the mass or the form is suddenly lifted from below and then after Withdrawal of support falls back on the mat under their own weight.

Incidentally, the shaking movement of the mass does not need during: the the entire duration of the driving process to take place, but can also be more or less experience large temporal interruptions. Although one should assume that it is for the achievement of a uniform and stable bubble or pore structure is crucial It should be important to keep the mass as calm and vibration-free as possible during the drift Left to its own devices, it has surprisingly been shown that the exercise the vibrations or shocks according to the invention without collapse of the bubbles to a possibly very substantial improvement of the structure and the properties the driven body can lead.

Above all, there is one against a mass floating at rest desirable retardation of setting so that the mass will be driven off with certainty before it begins to set to a significant extent. So the propellant can can be fully used to achieve maximum effect without - which is particularly important in the case of the masses processed according to the invention in an earth-moist state is - a premature decline in plasticity occurs. This will continue the tearing off of the: mass under your influence of the propellant effectively avoided. aside from that the periodic vibration of the floating mass apparently also leads to a Compaction and reinforcement of the cell walls, which, without reducing the overall porosity, have fewer capillaries, so that an undesirable high water absorption cannot take place. After all, there is a greater one with the shaken masses Elasticity in the selection of the type and grain size of the mineral aggregates.

Since the masses to be subjected to the driving process as a result of the invention small amounts of water to be used even after mechanical processing Circumstances are relatively dry and brittle: are, it has proven to be useful, a small part of the water, e.g. B. 2%, only after mixing in the propellant immediately before transferring the mixture into the mold and onto it Way to lubricate the mass, so to speak. This also increases the sliding ability the mass along the mold wall improved.

Apart from the already mentioned regulation of the bubble size and -structure through .the surface tension influencing additives, such as soap ,, can in the case of the mixtures prepared according to the invention all for hydraulically setting Mass customary measures apply. For example, plasticity the mass by using resin soaps in small amounts or by adding less Proportions of lime to cement binder are changed in a desirable manner. as well the setting time can also be reduced in the present mixtures by adding Abbreviate chlorides such as calcium chloride or aluminum chloride if necessary.

The setting or hardening of the masses or the; finished moldings can, depending on the choice of binder, in air or with steam, preferably under high tension Steam.

The process of the invention is explained in detail by the following examples: Examples 1 to 4 each comprise comparative tests with mixtures of the same type, which were probably processed according to the present process as in the hitherto customary manner using pourable slips. The dimensions given for the properties of the porous bodies obtained are in each case density and compressive strength. If hydrogen peroxide was used as a propellant, the information relates to 35 percent weight goods, while the added chlorinated lime contained 35 to 371 / o active chlorine. Example 1 The starting mixture consisted in each case of 550 g of quartz flour (10% residue on a 0.04 mm sieve) and 250 g of Portland cement.

a) 400 cc of water were added to the above mixture. After adding of 0.3 cc of 1% soap solution, 9 g of chlorinated lime and 2 cc of hydrogen peroxide the slip is poured into a shape with a square cross-section and the driving process left. After hardening in steam for about 6 hours. 12 atm resulted in a body with a density of 0.743 kg / l and a compressive strength of 85.5 kg / cm2.

b) 230 cc of water were added to the mixture of quartz powder and Portland cement and the resulting crumbly mass is intensively kneaded by hand for about 20 minutes. Then -the mixture with 0.3 ccm 1%, soap solution, 7.5 g chlorinated lime and 3 cc of hydrogen peroxide were added. As a result of the 42.5% lower compared to 1, a) Water content. the initial volume was only 650 cc, so that during driving to achieve approximately the same density as in 1, a) at least 230 ccm of gas more had to be developed. The molding was as under 1, a) in high pressure steam cured and had a density of 0.753 kg / 1 with a compressive strength of 127.8 kg / cm2.

The comparison between the previously customary slip process [1, a)] and the body produced according to the invention [1, b)] shows that the amount of water in the latter case was 42% less than for the production of a pourable slip is required. In spite of this, the compressive strength was about 50% higher with roughly the same volume weight. According to 1, a), 2 cc of hydrogen peroxide and 9 g of chlorinated lime were used to develop gas, while with mixture 1, b) a comparatively much larger volume of gas can be used for the propellant process from a smaller amount of chlorinated lime and only 50% more hydrogen peroxide . could. It can be seen from this that the process of the invention leads to a noticeable saving in propellants due to considerably better gas yield, without the properties or the propelled body being adversely affected in terms of density and strength. On the contrary, in many cases a substantial increase in compressive strength can be determined, which is possibly due to the fact that the pore walls are made more compact as a result of the low water content from the start than is the case with pourable masses with high water addition. Example 2 A mixture of lime and cement was used as a binder. The composition of the starting mixture was: 500: g quartz mill, 150 g white lime, 50 g cement.

a) The mixture given above became with the addition of 475 ccm Water, 15.7 g of chlorinated lime and 3.5 ccm of hydrogen peroxide, a pourable slipper manufactured. The initial volume was 830 cc. The driven body proved curing in high pressure steam has a density of 0.608 kg / l and a compressive strength of 72.1 lcg / cm2.

b) The processing of the starting mixture according to the method of the invention took place with the addition of 240 ccm of water followed by an intensive 20-minute session Kneading. Addition of 10 g of chlorinated lime and 4 cc of hydrogen peroxide resulted an initial volume of 620 ccm. To compensate for the initial volumes, in in this case. Additional effort of 210 cm3 gas required. After high pressure steam curing The result was a density of 0.630 l <g / l with a compressive strength of 97.5 kg / cm2.

The comparison of the amounts of hydrogen peroxide and chlorinated lime used also shows a considerably higher gas yield with almost the same amounts of hydrogen peroxide and lower addition of chlorinated lime for the method according to the invention. The amount of water was only about 50% compared to that in 1, a). Here, too, results from comparable Volume weights .an increased compressive strength in the case of the method according to the invention obtained moldings.

Example 3 In this case, the binding took place exclusively through Lime in a starting mixture of; 500 g of quartz flour and 100 g of white lime while 0.6 g of aluminum powder was used as the propellant. a) The slip was produced after adding 400 ccm of water and 2.5 g of chlorinated lime and after high pressure steam curing as in the previous examples gave one Moldings with a density of 0.576 kg / l and a compressive strength of 42.4 kg / em2.

b) With only 230 ccm of water and 2.5 g of chlorinated lime it was kneaded 15 minutes duration a molded body of 0.601 kg / l density and 59.4 kg / cm2 compressive strength obtain. The amount of water was 42.5% less than in Example 3, a).

EXAMPLE 4 From a mixture of 550 g of quartz flour, 250 g of Portland cement, 400 cc of water, 0.3 cc of resin soap (in 40% solution), 2.6 cc of hydrogen peroxide, 6.4 g of chlorinated lime, a molded body was produced which, after air-hardening, had compressive strength of about 28 kg / cm2.

The same mixture of quartz flour and portland cement was taken under Using only 215 cc of water (about 46% water saving) worked through for 20 minutes and then, after adding the other ingredients, driven into the shape as above. Of the The moldings formed had a density of 0.789 kg / l after air-curing a compressive strength of 48.4 kg / cm2 and thus achieved one for the present Conditions surprisingly high value.

By high-steam curing for 3 hours, the same mixture according to the method according to the invention for a density of 0.88 kg / 1 resulted in a compressive strength of 103.3 kg / cm2, which, even in view of the somewhat higher density of this sample, resulted in an extraordinary increase in the Represents compressive strength. Example 5 With a mixture of 100 kg of sand, 33 kg of cement, 181 water and appropriate additions of hydrogen peroxide, chlorinated lime milk and resin soap, after kneading. Molds of 20 X 20 X 20 cm are filled to a filling height of 10 cm and the filling is smoothed out. In each case one form was compressed on an upsetting table for 25 minutes, while the mass in a comparative form was left to the driving process without vibration. At the end of the test period, the compressed mass had been driven in to a height of 16.5, i.e. had experienced an increase in volume of 65%. At the same time the mass in the still standing form had swelled irregularly to a height of 13 cm; the increase in volume was therefore only 30%. When standing for a longer period of time, it was found that the non-compressed mass tended to collapse with a decrease in volume, while the force of displacement remained unchanged in the compressed form.

The examples show that the procedure according to the invention brings a number of significant advantages. Particularly noteworthy is that Saving of mixing water, depending on the grain size of the aggregate up to 50% and can optionally also be more. Needless to say, Working with less watery masses with regard to the weights to be enforced in the curing and drying of the moldings with a considerable technical and economic progress. Also the lower expenditure on propellants or the higher usable gas yield is an essential feature of the new one. Procedure, this also allows higher strengths to be achieved with the same amounts of binders to reach or, with the same strengths, to one of the known processes can lead to lower consumption of binders. The lower water content of the Mixtures according to the invention have an accelerating effect on the shrinkage process off, so that air-cured components made from these mixtures up to It only takes half to two thirds of the time to be ready for construction than those that are after the known slip process are made. Also for the susceptibility to corrosion any iron reinforcement in such construction elements is the low water content of the Masses an advantage. It has also been shown that the driving process en masse with the low water content according to the invention, preferably to a structure with open Pores leads. This promotes the release of water and continues drying accelerated. Such a pore structure is also suitable for components in which .ein good wall breathing is required, particularly cheap.

Slabs or stones made by the method of the invention and components made from it are particularly characterized by their good properties as a plaster base and have excellent adhesion for mortar layers. they are therefore very suitable for the construction of moldings in which the individual elements through thin mortar layers can be stably connected.

Claims (7)

PATEN TA NSPRÜCFIE 1. Process for the production of moldable, hydraulically setting porous masses, e.g. B. for the production of components consisting of mixtures of mineral substances, binders and water, using a gas propellant, characterized in that the mixtures are converted into a non-pourable mass of preferably crumbly, earth-moist consistency by appropriate measurement of the amount of water, an intensive kneading , e.g. B. a mixing kneading or milling, subjected and then driven by gases. 2. Procedure according to claim 1, characterized in that the gas propellant of the mixture only after mechanical kneading by carefully stirring in completely or largely avoiding additional kneading. 3. Procedure according to claims 1 and 2, characterized in that a small part of the amount of water, z. B. 2% of the mass to be subjected to the driving process after mechanical processing the mass and your mixing in of the propellant and immediately before molding is incorporated. 4. The method according to claims 1 to 3, characterized in that that the gas bubbles formed in the mixtures at least during the propellant process be subjected to periodically changing compression and expansion. 5. Procedure according to claim 4, characterized in that the mass of the action of mechanical and acoustic vibrations. 6. The method according to claims 4 and 5, characterized in that the mass is vibrated during driving and the shaking movement preferably in the direction of movement -the at; To drive resulting gas bubbles is caused. 7. The method according to claims 4 to 6, characterized characterized that the mass or that they, containing form of a Upsetting movement is subjected. B. The method according to claims 1 to 7, characterized characterized in that the size of the gas bubbles in the driven masses by: the Grain size of the mineral substances used is regulated and influenced Achieving fine-pored masses fine-grained aggregates, e.g. B. quartz powder can be used. 9. The method according to claims 1 to 8, characterized in that d: ate porous aggregates; such as fly ash or granular pumice, used when wet and the mixtures: can be produced without further addition of water. Considered publications: German patent specification No. 572 259.