A METHOD OF PRODUCING CONCRETE ELEMENTS

Abstract: A method of producing slab-like concrete elements having mutually parallel sides (2, 3) and containing one or more filling bodies (4), wherein a part (5) of the element which contains one or more filling bodies (4) is cast in a first manufacturing stage and allowed to harden, and wherein the hardened part is turned upside down and lowered into a mould (6) which contains fresh concrete, in a second manufacturing stage and the fresh concrete is allowed to harden. The invention is characterized in that in the first manufacturing stage the concrete is poured into the mould to a level (13) such that the upwardly facing side (7) of each filling body will be free from concrete; in that the free surface (7) of each filling body has provided therein recesses (9) whose combined volumes correspond to the variation in the amount of concrete used in the second manufacturing stage; and in that in the second manufacturing stage the first part (5) is lowered into the mould (6) containing fresh concrete to a level at which the element has a nominal thickness (t).

Description: A Method of Producing Concrete Elements The present invention relates to a method of producing concrete elements, and more specifically to a method of producing slab-shaped concrete elements which are intended to form or to be a part of a structural member in wall or floor structures. Such concrete elements have long been kncwn. The elements normally comprise a slab-like body having planar sides and being of uniform thickness and provided with filling bodies. The elements are normally manufactured by pouring concrete into a horizontal mould or form, wherein a part of the element which contains one or more filling bodies is cast in a first manufacturing stage. Subsequent to solidi¬ fication of this first part of the concrete element, it is turned upside down and lowered into a mould which contains fresh concrete, whereafter the fresh concrete is caused to harden, ϊhe volume of fresh concrete poured into the mould corresponds to the des.ired thickness of the concrete element. The concrete poured into the mould is vibrated and then allowed to harden. One very serious problem with such manufacturing methods is the difficulty found in achieving uniform qualities with regard to the thickness of the concrete elements produced, ϊhis difficulty is caused by the difficulty of controlling delivery of the concrete to the mould, such that the mould is filled with the same amount of concrete on each occasion. Because of these variations in the thicknes of the cast concrete elements, it is necessay to smooth and level the surface of the wall or floor constructed from said elements with filler, etc. This problem is solved by means of the present invention, which provides a technique in which concrete elements of precisely the same thicknesses are obtained. The present invention thus relates to a method of manufacturing slab¬ like concrete elements having mutually parallel sides and containing one or more filing bodies, wherein the part of the element which contains said one or more filling bodies is cast in a first manufac- turing stage and allowed to harden, and wherein said hardened part is turned upside down and lowered into a mould which contains fresh concrete in a second manufacturing stage and the fresh concrete is allowed to harden. The method is characterized in that in the first manufacturing stage the concrete is poured into the mould to a level such that the upwardly facing side of each filling body will be free from concrete; .in that the free surface of each filling body has provided therein recesses whose ccmbined volumes corresponds to the variation in the amount of concrete poured in the second manufacturing stage; and in that in the second manufacturing stage said first part is lowered into the mould to a level at which the element has a nominal thickness. The invention will now be described in more detail with reference to an exemplifying embodiment thereof and with reference to the accom¬ panying drawing, in which - Figure 1 is a cross-sectional view of a concrete element during its manufacture; and - Figure 2 is a cross-sectional view of a concrete element .shewn by way of example. Figure 1 is a cross-sectional view of part of a concrete element shown in Figure 2. The concrete element 1 has the form of a slab, having two mutually parallel sides 2, 3 and cxantaining one or more filling bodies 4. A part of the element which contains one or more filling bodies is cast in a first stage of the manufacture of the concrete element, this concrete element part be.ing the upper part 5 shown in Figure 1. Dur.ing this casting process, the side 2 forms the lower surface and concrete is poured into the mould to a level corresponded by the chain lines 13, for instance. Subsequent to having hardened, this first part 5 of the concrete element is turned upside down to the position shown in Figure 1 and is lowered into a mould containing fresh concrete, whereafter the fresh concrete is allowed to haiπien. The complete mould 6 is shown in Figure 2. According to the invention, in the first stage of manufacture the concrete is poured into the mould to a level at which the upwardly facing side 7 of each filling body will be free from concrete 8. This upwardly facing side or free surface 7 of each filling body has formed therein recesses 9, in accordance with the invention. The combined volume of the recesses 9 corresponds to the variation in the amount of concrete used when cast.ing in the second stage of element manufacture. According to the invention, the first part 5 is lowered into the ir xLd 6 containing fr-εsh concrete in the second manufacturin stage to a level at which the concrete element has a nominal thickness t- A typical thickness t of the concrete element is. e.g., 26 cm, and the filling body 4 may have a thickness of 16 cm. The concrete element will normally be reinforced, as indicated by the broken lines 10 in Figure 1. .According to one prefered e bodJLment of the invention, the volume of the recesses corresponds to about 10 percent of the ricminal amount of fresh concrete used, under normal conditions, this will ensure that a mould can be filled with a given nominal amount of concrete +/- 5 percent of the nominal amount, with a high degree of reproduceability. Figure l illustrates the case where the mould has been filled with a nominal amount of concrete and where the concrete takes up roughly half the volume of the recesses 9. Because the thickness of the concrete element is adjusted to the nominal thickness t, when the amount of concrete poured .in to the mould is smaller than the nominal amount, the concrete will take up less than half of the volume of the recesses, whereas when the amount of concrete poured into the mould is greater than the nominal amount, the recesses will be filled to more than half their volume. It is therefore obvious that the recesses function to equalize varia¬ tions in the amount of concrete poured into the mould, so that a concrete element of nominal thickness wiil always be obtained. .According to one preferred embodiment, the recesses 9 extend over the full length or width of the filling body 4, such that each recess will open out on at least one side of the filling body. This ensures that the concrete will be readily distributed evenly in the recesses. The recesses 9 preferably have the form of mutually parallel dales or troughs, which preferably have planar sides 11, 12. According to one preferred embodiment of the invention, the bottom angle of the recesses, i.e. the angle defined by the sides 11, 12, is about from 90 to 150 degrees. The depth of the recesses is about 10 to 25 percent of the thickness of the filling body. The filling bodies 4 may be formed from any suitable material, but according to one preferred embodiment of the invention are formed from a cellular plastic material. Such material is both heat and sound insulating and can be readily worked mechanically. It is evident that the invention solves the problem described in the iπtroduc±ion. Although the invention has been described in the aforegoing with reference to only one particular element, it will be understood that the invention can be applied in the manufacture of all slab-like elements having two mutually parallel sides and containing one or more filling bodies. The construction of the element and the form of the filling bodies can therefore be varied. The invention shall not therefore be considered restricted to the described and illustrated embodiment, since variations and modifi¬ cations can be made within the scope of the following claims.

Claims: Claims 1. A method of manufacturing slab-like concrete elements having mutually parallel sides (2, 3) and csDnteining one or more filing bodies (4) , wherein a part (5) of the element which contains said one or more filling bodies (4) is cast in a first manufacturing side and allowed to harden, and wherein said hardened part is turned upside down and lowered into a mould (6) whicii contains fresh concrete in a second manufacturing stage and the fresh concrete is allowed to harden, ch a r a c t e r i z e d in that .in the first manufacturing stage the concrete is poured into the mould to a level (13) such that the upwardly facing side (7) of each filling body will be free from concrete; in that the free surface (7) of each filling body has provided there.in recesses (9) whose combined volumes corresponds to the variation in the amount of concrete used in the second manufac¬ turing stage; and in that in the second manufacturing stage said first part (5) is lowered into the mould (6) containing fre^ concrete to a level at which the element has a nominal thickness (t) . 2. A method according to Claim 1, ch a r a c t e r i z e d in that the recesses (9) extend over the full length or width of the filling body (4) , such that each recess will open out on at least one side of the filling body. 3. A method according to Claim l or 2, c h a r a c t e r i z e d .in that the volume of the recesses (9) is caused to correspond to about 10 percent of the nominal amount of said fre^ concrete. 4. A method according to Claim 1, 2 or 3, c h a r a c t er i z e d in that the recesses (9) have the form of mutually parallel dales, which preferably have planar sides (11, 12) . 5. A method acording to Claim 4, c h a r a c t e r i z e d in that the bottom angle of the recesses (9) 12, is alxut from 90 to 150 degrees. 6. A method according to Claim 1, 2, 3, 4, or 5, c h a r a c- t e r i z e d in that the depth of the recesses (9) is about 10 to 25 percent of the thickness of the filling body. 7. A method according to Clam 1, 2, 3, 4, 5, or 6, c h a r a c- t e r i ze d in that the filling bodies (4) are made of a cellular plastic material.

Inventors: RYBERG NILS, RYBERG, NILS
Applicants: CONCRETE BUILDING TECH, CBT, CONCRETE BUILDING TECHNOLOGY AB
Application year: 1991
Main classification: B28B23
IPC codes: B28B23, E04C2