DD250925A1 - METHOD OF MANUFACTURING WOOD-CEMENT COMPOSITES - Google Patents

Abstract

The invention relates to a method for producing wood-cement composites, in particular for wood concrete, block or plate-shaped components for housing, corporate, industrial and agricultural construction. Using any kind of wood chips, including wood waste chips, wood-cement composite materials are to be produced in a technologically simple way so that wood ingredients with the cement binder do not react while simultaneously improving the adhesion between wood and binder. The produced wood-cement composite materials should have a high bending or pressure resistance and a good fire behavior. According to the invention, the object is achieved in that wood chips or wood pulps or organic fibers are chilled with a 0.2-10% aqueous suspension of silica sol, then with cement in a ratio of wood: cement 0.1-0.5 water: cement 0, 6 mixed and known to be further processed. The inventive building material can be used as light dividing walls, for Beplankungs- and sandwich panels, in the form of blocks u. ae., In the wet process as Daemmschicht find its application.

Description

According to the invention, this object is achieved in that wood chips or wood chips or organic fibers impregnated with a 0.2 to 10% aqueous suspension of silica sol, then with cement in a ratio of

Wood: Cement = 0.1-0.5 Water: Cement <0.6

mixed and known to be further processed.

Surprisingly, the method according to the invention produces a building material with good heat-insulating properties, which achieves high strength despite the low density due to the high proportion of wood. All previously negative influencing factors of the wood with the previous mineralization are eliminated. The silicification of the wood chips also creates a favorable fire behavior.

embodiments

The invention will be described in more detail by the production of wood-concrete and a plate-shaped component on a laboratory scale:

1. Wood Concrete: For the production of 4 test pieces (10 × 10 × 10 cm), 500 g chips (chips, chip residues) are first impregnated with 500 g of 1.5% silica sol suspension, then the spangle is mixed with a further 875 g silica sol suspension to set the cement and mixed, wherein this mixing process with the silica sol suspension proceeds in a continuous process.

Then the wetted chip material is mixed with 2 500g PZ 4/45 and the finished mix is filled into appropriate molds and compacted under load. After one-day solidification, the test specimens are switched off, stored at 2O ⁰ C and 90% relative humidity for seven days and then stored for 28 days under test at standard atmospheric of 20 ⁰ C, 90% relative humidity.

Before testing, the test specimens are subjected to drying at 100 ^° C. to constant mass.

The test specimens thus produced showed a

Bulk density of 0.78 kg / dm ³

Compressive strength of 21.76 N / mm ² .

2. Plate-shaped components: 175 g of waste sawdust are soaked in a 1.5% silica sol suspension by intensive mixing. Then 584g PZ 4/45 are added, creating a homogeneous, pourable or pourable raw material mixture with a water-cement ratio of 0.45 and a wood-cement ratio of 0.3. This mixture is poured on a plate of 25 x 35 cm ² base and evened out in height. Thereafter, the Rostoffgemenge is compacted by means of a suitable mold cover and a press at a pressure of 2.5 N / mm ² and clamped the plate-lid combination under pressure. After solidification for 16 hours, the finished plate is disassembled and stored in the moisture storage at 2O ⁰ C and 90% relative humidity until the seventh day after production. The plate is stored for a further 28 days and then stored under standard conditions (2O ⁰ C, 65% relative humidity). The plate is stored for another 28 days and then under standard conditions (20 ⁰ C, 65% relative humidity) tested.

In the equilibrium moisture condition, the following plate properties can be displayed:

Bulk density: 1.25 kg / dm ³ bending tensile strength: 12.35 N / mm ² compressive strength: 35.4N / mm ²

An accelerated solidification can also be done by a heat treatment of the plate blanks.

Claims (1)

Production method for wood-cement composite materials using any type of wood shavings, including wood chips and organic fiber materials, characterized in that wood chips or wood chips or organic fibers soaked with a 0.2-10% aqueous suspension of silica sol and optionally with other known additives or materials are charged, then with cement in a ratio Wooden cement = 0.1-0.5
Water: Cement <0.6 mixed and known to be further processed. field of use The invention relates to a process for the production of wood-cement composite building materials, in particular of wood-concrete, biock- or plate-shaped components for housing, corporate, industrial and agricultural construction. Characteristic of the known technical solutions In the application of cementitious building materials with organic fibers, the use of wood particles is a very common and very inexpensive fiber, since it is abundant as a waste material. In comparison to asbestos or synthetic substances, however, the wood particles contain harmful substances for the cement matrix, also referred to as cement poisons in DE-AS 1 696395. The damage caused by certain wood constituents is essentially dependent on the type of wood used and its pretreatment. In addition to the elimination of cement-damaging reactions, it is important to prevent the shrinkage and swelling of the wood and to establish a good bond with the cement. In practice, it is customary to subject wood parts, such as wood chips, before their further processing a mineralization process. The elimination of the negative effects of retarding the setting and the better adhesion to the binder, for example, by aluminum sulfate or heavy metal sulfates (DE-PS 915317, DE-AS 1 696395), by magnesium chloride, calcium chloride, sodium carbonate, magnesite or by formic acid, formates of the alkali, Alkaline earth or ammonium (DE-OS 2435105) achieved. These compounds mentioned create a layer on the wood, through which an insufficient connection with the cement is the result and thereby reduced strength in the building material can be generated. If fasteners are likely to be present, there is a risk of corrosion. Often alkalis are introduced into the concrete, which can cause harmful alkali reactions. In DE-OS 2715533 it is proposed to intensively mix the hydraulic binder (cement) with alkaline earth oxides or hydroxides, preferably calcium hydroxide, before adding them to the wood shavings. The addition of chlorides or similar accelerators is eliminated. Although this technology is, as it is shown in the exemplary embodiments, achieved a rapid hardening of the building material, but it requires high-quality wood chips, which must be enclosed on all sides by a very good mixing process of the binder. Errors in technology lead to severe quality losses in the manufactured building material. In addition, there is the risk of efflorescence of the finished building material by the calcium hydroxide. Object of the invention Wood-cement composites, in particular wood-concrete and chipboard, using any kind of wood shavings, of the desired quality and favorable burning behavior, are to be produced in a technologically simple way. Essence of the invention The invention has for its object to exclude in the production of wood-cement composites reactions of wood ingredients with the binder cement while improving the bond between wood and binder, building materials of this kind with high bending or compressive strengths produced under simple technological conditions should be.