DEVICE FOR MAKING OF POROUS CONCRETE

Abstract: Device for making of porous concrete intended for casting of e.g. elements of buildings, by which mainly cement, water and a frothing agent are mixed at the same time causing air pores in the mixture to be clasted, consisting of a cylindrical mixing-tank (1) in which an impeller (3) is arranged with a rotation axis which coincides with the centre axis of the mixing-tank (1) and by which the impeller (3) includes blades (31) that extend helicoidally along the mixing tank (1) by which the helicoidally of each blade is less than 90<o> over the length of the impeller (3) and by which the blades (31) extend a bit against the centre axis of the impeller (3). Each blade (31) consists of two, in direction to the centre axis of the impeller (3), reciprocally flat strips (32), which incline against the envelope to the mixing tank (1) so that the front edge in the moving direction of the outer strip (32) is located next to the envelope. Wings (33) are arranged between the strips (32) in each blade which incline against the centre axis of the impeller (3).

Description: DEVICE FOR MAKING OF POROUS CONCRETE The present invention relates to a device- for making of porous concrete intended for casting of e.g. elements of buildings such as foundation plate, walls and beams by which principally cement, water and a frothing agent are mixed at the same time in a way that air pores are obtained in the mixture for casting. A known method for making of porous concrete consists in that cement, and eventually sand, and water are mixed in a concrete mixer, after which a separately produced froth is lead into and mixed in the concrete. The concrete mixer is by that constituted by a fix tank provided with a rotating mixing screw or similar. The froth i produced by help of a device in which a frothing agent is mixed with air and eventually water so that a froth with small air bubbles is obtained. A device for producing such a froth is descrebed in the Swedish patent publication no. 156215. In order to abtain an equal quality of the cast porous concrete, i.e. an equal density and strength, it is required that the included raw material is mixed in the right proportions. At continuous producing, this has been found to cause problems as it requires a carefully measuring of the flows of raw material and a watching of the mixing times. Furher an effective mixing of the air is required in order not to get a too long mixing time. The object with the present invention is to bring about a device for making of porous concrete, which is more simple to use than devices known up to now and which ensures that an equal and high quality. is achieved at the cast porous concrete. The object has been achieved by a device in which all raw material is mixed in batches, which means that the raw material can be added in exact quantities. Further the mixing procedure is watched and controlled by a control equipment in the form of a micro-computer by which the mixing time and other mixing parameters can be kept equal for all batches under one and the same casting. The device consists of a cylindrical mixing tank in which an impeller is arranged with an axis of rotation which coincides with the OMPI centre axis of the tank, and characterized in that the impeller includes blades that extend helicoidally along the inner envelope surface of the tank, by which the heli- coidallity of each blade is less than 90 , preferably 40., over the length of the tank and by which the blades extend a bit against the centre axis of the impeller. Each blade preferably consists of two, in direction to the centre axis of the impeller, reciprocally parallel, flat strips which incline against the envelope of the mixing tank, so that the front edge in the moving direction of the outer strip is located next to the envelope. Between the strips, wings are arranged, by which respective wing is located in a plane which inclines against the centre axis of the impeller. Further, propeller blades preferably are arranged along the centre axis, which extend a bit from the centre axis. The blades preferably are supported by arms, which extend from the centre axis of the impeller and which carr ' a propeller blade each. A great advantage with the device in accordance with the present invention is that all raw material can be prepared in the one and the same apparatus. This one need no special device for producing of froth but prepare this at the same time as the porous concrete will be prepared by itself. This circumstance also has raised other demands on the design of the device compared with the known devices for making of porous concrete by putting in a prefabricated froth into concrete mixer. Surprising it has been proved that the characteristics of the invention are deciding in order to carry out the preparation in the one and the same device and obtain an equal quality of the porous concrete besides the advan- tages that are reached by the batch-wise preparation which is described above. The turbulence which is obtained in the mixture by the blades of the impeller and propeller blades makes a good mixing of the air which is in the tank to a porous concrete with uniformly spread pores. The device in accordance with the invention also constitutes a very compact unity which easily can be transported from one place to another arranged on a vehical for example. No training of the persons who are to handle the equipment is needed, why it can be used by everybody and can be rented to users for example. The invention is described below with references to an example of performance in connection to the attached figures. Figure 1 shows a concrete mixer as seen from one side. Figure 2 shows an impeller for the mixer in accordance with figure 1 schematically in a perspective. Figure 3 shows the impeller in accordance with figure 2 as seen in the direction of the rotation axis. Figure 4 shows a blade to the impeller in accordance with figure 2 and 3 schematically as seen from one side. Figure 5 shows the blade in accordance with figure 4 as seen from above. Figure 6 shows a cross-section of the blade in accordance with figure 4 along the line A-A. Figure- 7 shows a view over a blade in accordance with figure 5 along the line B-B. Figure 8 shows a cross-section of an impeller in accor¬ dance with figure 4 along the line C-C, by which the hub of the impeller is put down in the figure. Figure 9 shows the detail in accordance with figure 8 as seen from above. The invention in accordance with the example consists of a cylindrical mixing tank 1 which is arranged with an inclining centre axis on a stand 2. The mixing tank 1 encloses on impeller 3 with an axis of rotation which conin- cides with the centre axis of the tank and which is actuated by a motor 4 which is connected to the impeller 3 at the upper gable of the tank 1. At the top of the upper gable of the tank 1, a water tank 5 is affixed and connected to the mixing tank 1 by a water conduct 6 provided with a cut-off valve 7. In immediate connection to the water tank 5 also two tanks 8,9 for frothing emulsion are arranged and connec¬ ted to the mixing tank 1 by emulsion conduits 10,11 provided with cut-off valves 12,13. A funnel 14 for cement is arran¬ ged at the top of the envelope of the mixing tank 1 and surrounded by a stand 15 on which a transport container, shown dashed at figure 1, is placed at filling up. Down¬ wards at the lower gable of the mixing tank, a pump 16 is arranged for pumping the prepared porous concrete mixture by a flexible hose 17 to the place where the casting is to be carried out. Controlling and watching of the mixing proce¬ dure is done by help of a control equipment arranged in a locker 18 arranged in direct connection to the mixing tank 1. The impeller 3 comprises four blades 31, which extends helicoidally along the inner envelope surface of the mixing tank 1, by which the helicoidallity in accordance with the example is 45 over the length of the impeller 3 and by which the blades 31 extends a bit against the centre axis of the impeller 3. The helicoidallity is arranged against the direction of rotation which is marked with an arrow in figure 2. Further, the left gable of the impeller 3 in accordance with figure 2, is arranged at the upper gable of the mixing tank 1 in accordance with figure 1. Each blade 31 consists of two, in direction to the centre axis of the impeller, reciprocally parallell, flat strips 32 which inclines against the envelope of the mixing thank 1, so that the front edge in the moving direction of the outer strip 32 is located next to the envelope. Each strip 32 inclines 15 against the tangent to the rotation circle through the front edge of each strip 32. Between the strips 32, wings 33 are arranged, by which each wing 33 is placed in a plane inclining at the centre axis of the impeller 3. The plane through each wing 33 inclines 15 against a plane at a right angle to the centre axis of the impeller 3, by which the front edge of each wing 33 is located next to the left gable of the impeller 3 which in its turn is located at the upper gable of the mixing tank 1. The blades 32 are sup¬ ported by arms 34, which extend from the centre axis of the impeller 3. Four arms 34 are arranged on a hub 35 in a plane at a right angle to the centre axis of the impeller and in reciprocally right angles. Further, at the same hub 35,four_ O propeller blades 36 are arranged which each extend parallel to each arm 34. Each propeller blade 36 is inclining 15 at a plane at a right angle to the centre axis of the impeller 3, by which the front edge of each blade 36 in the same way as the corresponding front edge of the wings 33 in the blades 31 as mentioned above. At preparation of a porous concrete mixture for casting, a cement container containing a determined amount of cement is placed on the stand 15 on top of the mixing tank 1. The watertank 5 as well as the emulsion tanks 8,9 is filled up with water respective emulsions in proportions corresponding to the amount of cement. The cement after that is mannually pulled down into the mixing tank 1 by the funnel 14. After that the control equipment is switched on, by which the valve 7 at the water conduit 6 is opened, causing water to flow into the mixing tank 1. The rotation of the impeller 3 is started and is kept running for a determined time after which the control equipment opens the valve 12 at the emulsion conduit 10 from the first emulsion tank 8. The running of the impeller 3 is maintained for a determined time after which the control equipment opens the valve 13 at the emulsion conduit 11 from the second emulsion tank 9. After another determined time of running of the impeller 3, the porous concrete mixture is ready and can be pumped to the location for casting by the pump 16 at the lower end of the mixing tank 1 and by the flexible hose 17, which is con¬ nected to the pump 11>.

Claims: PATENT CLAIMS 1. Device for making of porous " concrete intended for casting of e.g. elements of buildings, by which mainly r-!f?ment, water and a frothing agent are mixed at the same time causing air pores in the mixture to be casted, con¬ sisting of a cylindrical mixing tank (1) in which an im¬ peller (3) is arranged with a rotation axis which coin¬ cides with the centre axis of the mixing tank (1) , by which the impeller (3) includes blades (31) that extend helicoi¬ dally along the inner envelope surface of the mixing tank (1) , by which the blades (31) extend a bit against the centre axis of the impeller (3) , c h a r a c t e r i s e d in that each blade (31) consists of two, in direction to the centre axis of the impeller (3) , reciprocally parallel, strips (32) which incline against the envelope of the mixing tank (1) so that the front edge in the moving direction of the outer strip (32) is located next to the envelope. 2. Device in accordance with claim 1, c h a r a c t e r i s e d in that wings (33) are arranged between the strips (32) in each blade, by which each wing (33) is located in a plane which inclines against the centre axis of the impeller (3) . 3. Device in accordance with claim 1- , c h a r a c t e r i s e d in that propeller blades (36) are arranged along the centre axis of the impeller (3) which ex¬ tend a bit from the centre axis. 4. Device in accordance with claim 3, c h a r a c t e r i s e d in that the blades (31) are supported by arms (34), which extend from the centre axis of the impeller (3) and which carry a propeller blade (36) each. OMPΓ

Inventors: DAHLIN PER OTTO, DAHLIN, PER, OTTO
Applicants: CELLEXFABRIKERNA AB
Application year: 1984
Main classification: B28C5
IPC codes: B01F7, B01F15, B28C5