Classifications

• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
  • C04B18/04—Waste materials; Refuse
  • C04B18/18—Waste materials; Refuse organic
  • C04B18/24—Vegetable refuse, e.g. rice husks, maize-ear refuse; Cellulosic materials, e.g. paper, cork
  • C04B18/28—Mineralising; Compositions therefor
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

• This invention relates to a method for treating wood wastes to be used as filling material for the manufacture of building elements consisting essentially of wood wastes and cement.
• Wood or wood waste consists of more or less carbohydrates, such as sugar and acids. These substances have a decomposition effect upon cement. Consequently, it is quite impossible to manufacture a durable concrete element containing wood or wood waste without first eliminating said decomposition effect. This problem has to be solved.
• the second problem involved in using wood or wood waste in concrete elements is that wood and cement are materials widely separated from each other with regard to properties of materials, such as coefficient of expansion for instance.
• the cement i.e. a common powdered, hydraulically settable material
• plastic with aqueous medium such as water and hardens on drying.
• the purpose is to form a continuous coating of cement slurry upon the surface of the wood wool or like'vegetable material and subsequent moulding the resultant mixture of wood wool and cement slurry.
• the only pre-treatment step is to wet the wood wool or like which is naturally retained on the surface thereof and t the load-bearing system in a concrete element.
• the final mineralized fibres of the fibrous material when considered in transverse section shows a structure which will be subdivided in several zones or layers of different character.
• the outermost zone is formed by pure cement, then follows a layer in which cement is mixed with the hardened gel, further in there is a thin layer of hardened gel, then comes a zone in which the gel is mixed with or has penetrated into mineralized fibre portions, and finally the innermost portion of more or less impregnated fibre material.
• the fibre material is completely protected against decomposition.
• this method has several disadvantages. The method is time-consuming as well as expensive.
• the present invention is based on the idea of achieving a firm film around the woo-d waste pieces with such characteristics that the pieces become encased in such an effective way that the injurious substances can not pierce the film and damage the cement in the concrete. Furthermore, the film is permanently effective to hinder the injurious substances from passing through after some time. Finally, the film is such that the cement in the cement mortar for the manufacturing of the concrete elements effectively binds on the film.
• the method according to the invention for treating wood wastes to be used as filling material for the manufacture of building elements consisting essentially of wood wastes and cement comprises the steps of powdering onto and rubbing into thoroughly moistened pieces of wood waste cement clinker, that is, portland cement without the admixture of gypsum, wh reby the pieces of wood waste are rapidly encased, and drying the surface of the thus treated pieces of wood waste so that a firm film is formed around each of said wood waste pieces.
• the present invention also relates to a method for manufacturing building elements consisting essentially of wood wastes and cement comprising the steps of powdering onto and rubbing into thoroughly moistened pieces of wood waste cement clinker, that is, portland cement without the admixture of gypsum, drying the surface of the thus treated pieces of wood waste so that a firm film is formed around each piece of said wood waste, mixing the dried, treated wood waste pieces with cement and water, whereby the cement in the water binds on the film on each piece of said wood waste, and thereafter molding the resulting mixture into a building element.
• the initial material used e.g. the wood waste pieces
• the powdering and rubbing operation as well as the subsequent drying step affects only the surface
• the interiors of the wood waste pieces have a high moisture content even after the powdering, rubbing and drying operation.
• the building element when the building element is in its ready state and finally dry, it is given a high porosity; that is, the wood waste pieces will then shrink. It is, first and foremost due to this porosity that a building element having filling material pre treated according to the present invention has low density, low swelling and good heat and sound insulation.
• the wood waste pieces lie within the firm film as dried pips in a core. The shrinking continues by time and furthermore a certain decomposition of the wood waste pieces takes place. Thus, the porosity even increases in time.
• a building element manufactured according to the present invention has furthermore the essential advantage over the, up till now, known methods, that only the concrete is load-bearing.
• the wood waste pieces, which at the pretreatment process are thoroughly moistened and they then have their largest volume, lie as mentioned above when the element is in its finished state as dried pips in a core.
• the wood waste pieces are not part of the load-bearing system.
• the problems associated with the different mechanical properties for different materials in the load-bearing system for a building element consisting of said different materials, such as modulus of elasticity are eliminated.
• This also means a comparatively larger compressive strength for a building element manufactured according to the present invention.
• the amount of bark to be used is preferably such, that the final product contains 30-70 percent by weight of dry bark, but it may even contain between and 90 percent by weight.
• the wood waste or other wood waste material When being powdered and rubbed the wood waste or other wood waste material should have a moistness of about 35%. This moistness is obtained, for example, by maintaining the bark for a longer period in a water store and subjecting it thereafter to centrifuge treatment. However, wood bark or other wood waste material having a moisture content of between and 70% is also useful in the present invention.
• the film resulting from the powdering and/or rubbing step may be moistened outwardly after drying, thereafter the bark pieces are powdered again with cement clinker, that is, portland cement without the admixture of gypsum, and finally dried outwardly before the said pieces are mixed with the remaining components of the building element.
• the moistening of the film obtained by the first powdering and/or rubbing step is preferably carried out such, that the bark is passed through a shower bath, that is, subjecting the bark to a slight water sprinkling.
• Both the first and the second powdering or rubbing operation is preferably performed in such a manner, that the bark and the said cement without setting time control are rotated together in a slowly rotating drum whereby the cement is partially rubbed into the voids of the bark and thereby closes the same in an effective manner.
• the interior of the bark has even after the glazing operation a very high moisture content.
• the glazing i.e., the powdering and subsequent drying
• the interior of the bark has even after the glazing operation a very high moisture content.
• the building element in ready state is finally dried, it is given a high porosity, as the bark then will shrink.
• the finished building element has low density, low swelling and good heat and sound insulation.
• the advantage of using cement which has no controlled setting time lies in the fact, that this cement is setting rapidly when it is brought into contact with the moist bark surface. This results further in a highly effective encasing of the components comprised in the bark, for example sugar, which otherwise for example would deteriorate the adhesion between the bark and the cement mortar.
• a ready dried slab may have the following composition (irrespective of that it contains even a certain amount of water).
• the composition percentages given below are by weight of the individual constituents in the composition:
• Cementl0-50% preferably 15-30% Bark90-l0%, preferably -30% Sand-0-50%, preferably 15-30% Slag0-50%, preferably 0-30%
• the total percentage of the individual constituents of the composition must, of course, not exceed 100%. In this regard when, for example bark is used, no sand or slag can be added, because there must be a cement content of at least 10%.
• Bark of fir and redwood is taken from a water store (even other bark types may, however, be used).
• the bark is dried, for example by passing it on a belt through a heating and/or ventilating arrangement.
• the glazed bark is sprinkle-d with water, for example by passing the bark on the same belt as in point (6) through a shower arrangement.
• the manufacture of a slab requires, for example, not all of the aforesaid twelve steps in order to satisfy the requirements listed at the beginning of the description and to have a strength which by far exceeds that of usual lightweight concrete, but yet has a density below 1.
• the steps 7-9 may be deleted. It is, furthermore, possible to exchange certain steps against equivalent ones.
• the powdering must not be carried out in a rotary drum, but may, for instance, occur by means of pressure-spraying.
• a method for treating wood waste to be used as filling material for the manufacture of building elements consisting essentially of wood wastes and cement which comprises the steps of powdering onto and rubbing into thoroughly moistened pieces of wood waste cement clinker (portland cement without the admixture of gypsum), whereby the pieces of wood waste are rapidly encased, and drying the surface of the thus treated pieces of wood waste so that a firm film is formed around each piece of said wood waste,
• a process according to claim 1 wherein the firm film formed around the said pieces of wood waste is further moistened after the initial drying step, said moistened pieces of wood waste being subjected to a powdering and rubbing step with cement clinker, and thereafter drying the surfaces of said treated pieces of wood waste prior to being used as a filling material for the manufacture of building elements.
• a method for manufacturing building elements consisting essentially of wood wastes and cement, which comprises the steps of powdering onto and rubbing into thoroughly moistened pieces of wood waste cement clinker (portland cement without the admixture of gypsum), drying the surface of the thus treated pieces of wood waste so that a firm film is formed around each piece of said wood waste, mixing the dried, treated wood waste pieces with cement and water, whereby the cement in the water binds on the film on each piece of said wood waste and thereafter molding the resulting mixture into a building element.
• a process according to claim 3 wherein the firm film formed around each piece of said wood waste is further moistened after the initial drying step and subjected to a powdering and rubbing step with cement clinker, thereafter drying the surfaces of said treated pieces of wood waste prior to their use as a filling material for the manufacture of building elements.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Ceramic Engineering (AREA)
• Environmental & Geological Engineering (AREA)
• Civil Engineering (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=20271103

Family Applications (1)

Country Status (3)

Cited By (23)

Citations (9)

• 1962
  • 1962-07-11 DE DE19621471355 patent/DE1471355A1/de active Pending
  • 1962-07-13 FI FI134962A patent/FI44101B/fi active
• 1966
  • 1966-01-25 US US52284866 patent/US3403205A/en not_active Expired - Lifetime

Patent Citations (9)

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