Uhliarik, Stanislav Peter (Johannes Poststraat 36, PJ Heemskerk, NL-1964, NL)
|1.||Building element comprising cement, waste sludge and fiber ingredients as main constituents, characterized in that the amount of sludge and fiber ingredients which are in the form of coarsecut woodchips, together constitute a substantial main portion of the material in the element, that the proportion of woodchips is approximately equal to or larger than the proportion of sludge, that the proportion of cement has an order of magnitude of 10% and that during the manufacturing of the element the sludge is introduced with a degree of moisture of about 60 to 70%.|
|2.||Building element according to claim 1, characterized in that the amount of sludge and woodchips, together constitute at least 3/4 of the material in the element.|
|3.||Building element according to claim 1 or 2, character¬ ized in that the proportion of cement constitutes 8 to 12% of the material in the element.|
|4.||Building element according to claim 1, 2 or 3, charac¬ terized in that the proportion of sludge constitutes 25 to 45% and the proportion of wood chips constitute 45 to 60%.|
|5.||Building element according to any one of claims 1 to 4, characterized in that during the manufacturing of the element coarsecut wood chips are introduced with a degree of moisture of 20 to 25% and with chip lengths generally within the range 10 to 70 mm.|
|6.||Building element according to claim 5, characterized in that the woodchips are treated beforehand with water glass before introduced during the manufacturing and that the proportion of water glass in the material of the element is up to 10%.|
|7.||Building element according to any one of claims 1 to 6 manufactured in plate form, characterized in that the element is compressed under a pressure of 3.5 to 5 tons per 3 m during up to 48 hours.|
|8.||Building element according to any one of claims 1 to 6 manufactured in block form, characterized in that the element is compressed in a mold under a pressure of about 3 3 to 3.5 tons per m and during a compression time of the order of magnitude 24 hours.|
The invention relates to a building element, in particular in the form of a formwor block for use in the building industri. Builing elements can also be other forms of building blocks and besides plate-shaped elements.
As a formwork block (building block) the element can be heat insulated or not insulated, and it is manufactured with sewage and/or industrial waste as an important main constituent.
On the background of strong trends in the environmental field as regards the consumption and deposition of waste or sludge from various purification and industrial plants, as well as the formidabel expenses involved, it emerges as an ideal solution of the problem to employ the sludge for the production of some form of building element or material.
Previously there are various proposals known for utilizing sludge and waste in building materials.
German patent 3,149,173 is directed to a building material based upon industrial waste in the form of an aluminum composition as a main component (sludge) and besides containing among other things a fiber material, such as waste paper.
German patent application 3,808,187 describes a building material in granular form manuf ctured of household or industrial waste among other things, and with various additives, for example lime. A relatively cumbersome production method is thoroughly described.
German patent application 3,832,771 is closely related to the preceding patent application, and is more particu¬ larly related to the production of a material in the form of small spheres.
As far as building elements are conserned, Norwegian patents 154,267 and 157,213 relate to the manufacture of building plates by means of a specific method with waste fibers as a constituent.
German patent application 3,440,704 shows a building or formwork block incorporating insulation, groove and tongue connections as well as cavities for the casting of concrete.
The above and other known proposals have not resulted
in building elements which to a sufficient degree fulfill the reguirments imposed on one hand to the usefulness of the elements within in the building industry, and on the other hand to an efficient and economically advantageous utili¬ zation of waste material which at the outset represent great environmental problems. In this connection, there is a desire for among other things a product having good mechanical strength properties and a favourable weight, simple and rationalized production which does not require much energy, and consumption of relatively large amounts of waste and/or sludge, whereby variations in the sludge type or composition should not be critical for the resulting product.
According to the invention this has been made possible in a building element comprising cement, waste sludge and fiber additives as main constituents, aiming at among other things an advantageous utilization of sewage and industrial sludge, the novel and specific features of which consist therein that the amount of sludge and fiber ingredients which are in the form of coarse-cut woodchips together constitute a substantial main proportion of the material in the element, that the proportion of woodchips is approxi¬ mately equal to or larger than the proportion of sludge, and that the proportion of cement has the order of magnitude 10% and that during manufacture of the element the sludge is introduced with a degree of moisture of about 60 to 70%.
As already mentioned such a building element can with advantage be designed as a formwork block, and in actual practice each such block has a suitable cavity giving room for sanitary and electrical installations (so-called hidden insulation) , at the same time as supporting structures (reinforced concrete) can be provided internally in the blocks. Moreover, there is space for a desired choice of installation layer (isopor, polyurethane, etc.). In order to simplify the joining of the formwork blocks, i.e. the stacking thereof, the blocks can be provided with grooves and tongues, as well as spaces for reinforcement iron horisontally and vertically. When the stacking of the
formwork blocks has been done, the cavities of the blocks are filled with concrete (after having mounted the desired installations). Thereby the supporting, static properties are obtained for any kind of building and load. A concrete- filled formwork block based on the solution given here, excludes the possibility of thermal bridges, and an additional advantage is represented by the fact that the insulation layer can be located in the interior of the block, but outside the concrete mass and not vice versa, as is the case with other building or foundation blocks.
As a consequence of the composition of the building elements or formwork blocks, it is possible to saw, screw or nail directly into the blocks. Moreover, the formwork blocks will have a high safety against fire. Such a formwork block is free of bacteriae, in spite of the type of main constituents being involved in the manufacture. In order to avoid direct contact, however, the blocks should normally be plastered at the inside and outside.
This building element, either in block form or in a plate shape, is manufactured mainly of sewage and/or industrial sludge to which there is added an equally large or larger proportion of fiber in the form of coarse-cut woodchips and cement. As mentioned, the resulting product will among other things have relatively good elasticity and strength properties.
Both when the product is in the form of a building or framework block and in the form of a plate element, it is intended in regular applications in building structures to combine such elements with other load-carrying structural elements or materials in the building, such as by casting reinforced concrete in the cavities of the formwork blocks. This means that the requirements to mechanical strength in these building elements are relatively moderate. In view of this favourable combination of materials and elements in a building structure, this invention makes it possible to manufacture building elements based on cement, waste sludge and fiber ingredients as main constituents, involving advantages as mentioned above.
When waste sludge is referred to here, this can be sludge of various types, mainly sewage or household sludge, for example from public purification plants, and various types of industrial sludge. In the case of clearly toxic industrial sludge, for example containing dangerous heavy metals or radioactive substances, this may be a reason for being careful with utilization in the present building elements. In the present-day society and industry there is, however, generated so large amounts of ordinary sludge of various kinds and without any particular constituents representing problems, that a production of building elements as described here will be a substantial aid in having such waste sludge disposed of.
In the patent claims it is stated more closely how the proportion of the various constituents in the building element shall be in order to obtain the desired results and properties in a substantially complete or optimal manner. In practice there will be certain tolerances in the compo¬ sition of the material in the building elements, depending among other things upon available waste sludge and the properties of use required from the building elements. In the following description and in the claims percentages of weight are quoted when proportions by percent of the constitutents in the building element are referred to.
After elaborate experiments and tests based upon the idea forming the bases of the invention, it has been found that a production having a good result is obtained with a material composition having typical values as stated in the following table, in which the material consumption refers to a cubic meter of compact mass for blocks or plates:
Cement, white, quality PC 400 250-350 kg 8-12%
Sludge L Loooossee 'weight : 710-720 kg/m 3 290-465 kg 25-45 Moisture : 60-70%
Coarse cut woodchips:
Loose weight 120-130 kg/m .3 J , 1,3--,1, -7 _πT3 45-60g.
Length 10-70 mm
Weight : 100 kg/m /woodchips 7-10 J
(Specific weight 1366 kg/m )
The percentage figures in the rightmost column in the above table are based upon the percentage of weights of the respective material constitutents.
During manufacture of blocks there is preferably employed a compression of 3 to 3.5 tons per square meter during a compression or treatment time in suitable molds, of typically 24 hours. Uncompressed or loose mass can before compression be filled to a hight of 30 to 35 cm for producing blocks having a final or compressed height of 25 cm as a result of the compression force employed.
The coarse cut chip constituents in the material in many cases may take the form of a waste product or it can be. specifically produced from waste timber, for example from birch or fir, and the fiber ingredient is washed or impregnated with water glass before being mixed with the remaining constituents for filling into the molds mentioned and subsequent compression as described above. During compression in the molds heat may be added, for example heating to temperatures of about 60°C or higher throughout the first couple of hours of the treatment time in the molds. Such heating, however, is not necessary and as a
rule not desirable, so as to keep the energy consumption low in the production. The moisture relationships and how quick curing and drying of the blocks are desired, are important factors here. A major condition is that the waste sludge employed has a degree of moisture of 60 to 70 or 75%. A somewhat higher degree of moisture of the waste sludge seems to be possible for the production of plates.
When producing plate elements the compression may be in the range from 3.5 to 5 tons per square meter and with a compression time of up to 48 hours. The thickness of the plate element in non-compressed form can be 80 to 90 mm with a compression down to for example 35 mm or other alternative thicknesses which may be desired in the finished plates.
The materiale composition in the plate elements can be somewhat modified in relation to what is referred to above specifically relating to blocks. Thus, for the production of plates there can be employed cement of quality PC 440 and a somewhat smaller amount of water glass, typically
3 about 30 kg/m mass or material for plates, and adding water in the amount of about 100 liter.
As a building block and particularly as a formwork block the outside dimensions can suitably have a lenght of 1 meter and width 30 cm and a height of 25 cm as already mentioned above. The height can be directly de ermined by the compression into the molds, or it can be adjusted by sawing at a height of 25 cm after curing and drying, so that crimping of the block is avoided, at the same time as securing that this important outer dimension is exactly maintained.
In the drawing there is illustrated an exemplary embodiment of formwork block according to the invention, in this case including heat insulation.
More particularly the formwork block in the drawing has a sidewall 1A which is preferably intended to be an inner wall, and another wall IB which correspondingly can be an outside wall in a finished wall structure. An insulation layer 2 is provided at the inside of the outer wall IB. At
3A and 3B there are shown a groove and a tongue respec¬ tively, for the best possible mutual aligning and joining of adjacent blocks in a wall. Moreover there is shown a recess 4 in the end wall of the block intended for arranging reinforcement rods and for extending electrical installation wires and the like. The inner cavity 5 can also serve to accomodate sanitary and electrical installations and then to be filled with concrete, so that a sufficient mechanical or load carrying strenght is obtained in the finished wall structure. At 6 there are indicated possible subdivision points in the event that it should be desired to cut a comparatively long formwork block into shorter pieces.
A building block or formwork block is described here and having a material composition within the ranges quoted, will for example have a breaking strength at compression of 3.5 MPa. it should also be mentioned that for the purpose of manual work with the blocks, for example by self builders, the weight should not be too high. To a large degree the weight will be determined by the sludge quality and the amount of cement as well as the final moisture content after the manufacturing process. As regards the contents of cement it will be understood that the low percentages mentioned, are favourable both with respect to weight and economy.
Advantages and use properties as described above with respect to the block element, substantially and quite correspondingly will be present in the embodiment of the present building element as a plate. Employed as outside wall plates these can be plastered or be provided with wooden panels. Interior wall plates can be used without any treatment or can possibly be painted, provided with wood panels, wall paper, coated with tiles or the like. The dimensions of a wall plate of this type can be a height of 50 cm, length 200 cm and thickness 3.5 to 5 cm. In a wall structure being advantageous in practice, the plate elements according to the invention can be employed as an outside wall part, whereas the cooperating inside wall part can be formed of plaster board or the like. It is an advantage to
have an insulation layer integrated with or located at the inside of the exterior wall element. As in the block embodiment such a wall structure can obtain its mechanical or supporting strength mainly by casting preferably rein¬ forced concrete between both wall parts.