METHOD AND MEANS FOR THE MANUFACTURING OF LIGHTWEIGHT-CONCRETE

Abstract: By the known methods for the manufacturing of lightweight-concrete great mixing units are used together with autoclaves in which the deposited concrete elements are hardening. This does not make it possible to deposit the concrete on the building site, and the size of the autoclave limits the size of the elements. This need is supplied by means of a method, where the individual mixing tanks are independent mixing units with agitator mixing by means of a pump which through circulation to the tank is circulating and thus mixing the materials. By letting the last but one tank (4, 5) be a measuring tank and the last tank (6, 7) a plant-mixing container, where the gas generating means are added, a continuous concrete manufacturing is achieved, which can be adjusted according to the requirement. Furthermore the cleaning of the plant is very simple, as the water is allowed to pump through the plant and rinse this. By using partly reaction means and partly gas generating means a lightweight-concrete may be manufactured which hardens at a normal temperature and pressure in atmospheric air, and by which the autoclaving can be totally avoided.

Description: METHOD AND MEANS FOR THE MANUFACTURING OF LIGHTWEIGHT-CONCRETE. The invention relates to a method and means for the manufacturing of light-weight concrete with innumerable small closed cavities on basis of usual ingredients, namely concrete, sand, water and gas generating means. Lightweight-concrete, which is concrete with a specific gravity of between 600 and 1200 kg/cubic metre is manu¬ factured on basis of concrete with admixed gas genera¬ ting chemicals, where gas blows occur by gas generation in the fresh concrete. After placing this concrete in forms, the concrete will swell on account of the gas generation. After the swelling in the form the surface can be scraped off, so that smooth lateral faces will occur all over the castings. Then the castings may be cut into suitable pieces, f.ex. by means of wires which are drawn through the castings, and the pieces are lead into an autoclave in order to harden in the steam cham¬ ber. After the treatment in the autoclave the light¬ weight-concrete elements are ready for use. For this manufacturing of lightweight-concrete elements permanent plants are used, as the requirements of ope¬ ration and equipment are of such a size that the most profitable manufacturing Is achieved in this way. The size of the elements is limited by the chamber size of the autoclave, and the usual manufacturing is there¬ fore restricted to building blocks and rather small elements. Further it is only possible to deposit the lightweight-concrete in a form in a way which requires a succeeding adjustment after the depositing in order to make the surface even and in order to fill the form totally. This means that the depositing must take place with a surplus of concrete which is later on scraped off, and it is not possible to use the scraped off ma¬ terial again. Furthermore the concrete is manufactured in such plants where the manufacturing cannot be regu¬ lated in dependence of the consumption and consequently it cannot be adjusted to the consumption in a suitable way. It is the object of the present invention to supply these wants of the known methods, and this is achieved when water and concrete are supplied to the first mix¬ ing tank with a connected pump which mixes by the cir¬ culation to the tank,, whereupon the mixture is lead to the second mixing tank, where sand is supplied and where the mixing also takes place by means of a connec¬ ted pump with circulation to the tank, whereupon the mixture is lead to an intermediate tank, where the con¬ sistency of the mixture is adjusted and where the mix-' ing also takes place by means of a connected pump with circulation to the tank, whereupon the mixture is lead to one or more measuring tanks from where a measured/ weighed quantity is lead to one or more plant-mixing containers where the measured/weighed means necessary for the gas generation are supplied and admixed by means of a connected pump with circulation to the tank and from where the plant-mixed concrete can be drained off. Thus a simple and very economic concrete manufacturing is achieved, as it is firstly possible to manufacture the concrete in the necessary quantity, i.e. according to requirement, and further it is sufficient to pour the necessary and sufficient quantity plant-mixed con¬ crete in the form as the concrete after the gas genera¬ tion will fill up the form totally. Thus the scraping off is saved as well as loss of concrete and much work. Further the method makes it possible to use smaller mix¬ ing plants which can f.ex. be made mobile. Therefore OM WIP the manufacturing of concrete can take place directly on the building site, which means a great economic ad¬ vantage and also a considerable rationalization of the building construction. Finally the agitator mixing by means of the pump mixers means a simple and efficient mixing, and the pumps are at the same time used for leading the mixture from tank to tank and to the place of working. This means that the plant may be simplified and further it is easy to clean after use, as the plant has only to work with clean water which is drained off after having passed through all units. By using the method according to claim 2 an especially favourable concrete mixture is achieved partly because the ingredients are efficiently mixed with adjusted water content, and partly because the final mixture with the gas generation means is facilitated by the smaller admixed ' quantity. The finished concrete will then be fully homogeneous. Finally the means for the performance of the method according to claim 3 are particularly advantageous, as they make it possible to harden the poured concrete at a normal temperature and pressure in atmospheric air, and thus it is possible to manufacture concrete ele¬ ments without needing time in the autoclave for the hardening. This is another advantage by mobile plants which are to be as light and simple as possible. Fur¬ ther the highly energy requiring autoclaving is avoided, In the following the invention will be further descri¬ bed with reference to the drawing which shows the me¬ thod in a schematic view. As illustrated on the drawing the performance of the method is initiated by supplying to the first mixing OMPI_ tank 1 suitable quantities of concrete and water which will be explained later on. The reaction means, i.e. the parts of the gas generating means which do not by themselves generate gas, may be added together with concrete in the first mixing tank, whereby the mixture will be an optimum, as the concrete and the reaction means are mixed through the whole plant. The mixing of the concrete parts in the tank takes pla¬ ce by means of a pump 10 which has to be a pump for strongly grinding mediums. A preferred pump has a pump body with rotor bladewheels as well as centrally placed inlets and a pressure socket placed along the circumfer¬ ence. From the bottom of the tank the mixture slides in¬ to the pump 10 and from the pressure socket of this further on into a closed pipe 11 to a valve 30. From here the material can either be pumped through a cir- culation back to the tank 1 or, through blockading of this circulation and opening of the valve 30 for further transportation, it may be pumped to the next mixing tank 2. This agitator mixing of the materials in the tank is particularly efficient, as everything passes through the pump in which the dispersing takes place. At the same time the pump is utilized as the materials are either mixed or transported by means of the pump during the operation. In the next mixing tank 2 a suitable quantity of sand is added. Then it is mixed by means of the pump 12 and the circulation via the pipe 13 and the valve 31. When the mixing is finished, the circulation is blockaded at the valve 31, and a pipe is opened to an intermedia- te tank 3- In this tank the moisture content of the mixture is controlled by means of a meter 15 and ad- - fEA OMPI 1 ' justment is made, f.ex. by means of a water adding de¬ vice 14. By this the proper consistency of the mixture is ensured. Also in this tank an agitator mixing takes place by means of a pump 16 with circulation through a • 5 valve 32. From the intermediate tank 3 the mixture is pumped via the pipe 17 and a valve lδ to one or more measuring tanks' 4 and 5. When a certain quantity of concrete has 0 been pumped f.ex. into the tank 4, which is registered in the shown example by a weighing device 19, the sup¬ ply of concrete is interrupted by the valve 18. Then the agitator mixing 6 is opened for draining off. 5 In this container 6 the gad generating means, f.ex. aluminium powder, is finally supplied to the concrete, for instance via a weighing device 21. The whole mate¬ rial is agitator mixed by means of a pump 23 which agi¬ tator circulates the concrete via a circulation 25 and 0 blocking valve 33- When the mixture is ready the pumping 11 to the place of concreting can take place through .blockading the valve 33 and through opening of the valve 8 to the outlet pipe 9 . 5 The form 27 is shown to the right in a reduced scale and in vacant condition. In the middle the form is shown in filled condition and with a meter 28 placed in the form, so that exactly the quantity of concrete can be filled in which is necessary to fill the form totally 0 after the swelling of the concrete. To the left the form is shown with swelled concrete, the surface of which centres exactly with the upper edge of the form. In the shown example of a mixing and dosing device there 5 are two measuring tanks 4 and 5 and corresponding agita¬ tor mixing containers 6 and 7. However, It may also be possible to use a greater number of chambers, as this depends on capacity and need of variation of this. The best economy is achieved when the mixing is exactly suf¬ ficient to cover the concreting demand as mixed concre- te cannot be storaged for a long period. In the following is mentioned an example of ingredients per cubic metre ready concrete. ■ Concrete 400,- kg Sand 380,- - Aluminium powder 0,6 - Reaction means 8,25 - Water corresponding to a water/concrete proportion of 0,60. As reaction means can be used a mixture of f.ex. ferro- silicon, condensate of melamine and formaldehyde and sodium flouride. The reaction means are without oxygen and other ingredients which give damage to concrete. Any generally existing kind of sand with a particle size of up to 1,5 mm can be used. The mixture hardens chemically in air. The ready mixture is easy flowing and distributes in the form like a fluid contrary to usual concrete which is to be vibrated. Within one hour the volume is increased by about $5% and after 24 hours the form may be emptied. The specific weight is now about 800 kg/cubic metre and the surface is even all over. The lightweight-concrete can be concreted together with general concrete elements, and can furthermore be reinforced in the usual way. The specific weight may further be regulated within wide limits depending on the mixing proportion, and other materials can be added according to requirements such as perlite, vermiculite, dying means etc. If an extra coating on one lateral face of an element is required, It is further possible to pour out a thin flowing surface coating layer after the concreting in the form. It is implicit that this method can also be used for manufacturing elements which are concreted in situ, f. ex. by concreting around reinforcing iron in f.ex. buildings, and the plant may also advantageously be used for manufacturing usual known mortar and concrete. The method is economic in use as it mixes the ingre¬ dients efficiently together, which means that these are utilized to an optimum, and the finished product will be of an even quality. The plant is simple and non- expensive as well concerning the manufacturing as the operation, adn it has a high efficiency. OMPI .

Claims: C L A I M S 1. Method for the manufacturing of lightweight-concrete with innumerable small closed cavities on basis of usu¬ al ingredients, namely concrete, sand, water and gas generating means, c h a r a c t e r i z e d i n that water and concrete are supplied to the first mixing tank (1) with a connected pump (10) which mixes by the circulation to the tank, whereupon the mixture is lead to the second mixing tank (2), where sand is supplied and where the mixing also takes place by means of a connected pump (12) with circulation to the tank, where¬ upon the mixture is lead to an intermediate tank (3), where the consistency of the mixture is adjusted and where the mixing also takes place by means of a connec¬ ted pump (16) with circulation to the tank, whereupon the mixture is lead to one or more measuring tanks ( 3 5) from where a measured/weighed quantity is lead to one or more plant-mixing containers (6,7), where the meas¬ ured/weighed means necessary for the gas generation are supplied and admixed by means of a connected pump (23, 24) with circulation to the tank and from where the plant-mixed concrete can be drained off. 2. Method according to calim 1, c h a r a c t e¬ i z e d i n that the ingredients of the gas gene- ration means, which do not by themselves generate gas, are added together with the concrete in the first mix¬ ing tank (1), while the ingredients able to generate gas are first added to the plant-mixing container (6,7). 3. Means for the performance of the method according to claim 1 and 2, c h a r a c t e r i z e d i n that the ingredients of the gas generation means which do not by themselves generate gas, are made out of reaction WIPO means, while the gas generating ingredients comprises f.ex. aluminium powder. OMPI ltZn

Inventors: MORTENSEN S
Applicants: MORTENSEN S, SAAMOCONSULT APS
Application year: 1979
Main classification: B28C5
IPC codes: B28C5