HK1069378B - Method for producing concrete or mortar using a vegetal aggregate - Google Patents

Description

Method for producing concrete or mortar by using plant aggregate

The invention relates to a method for producing concrete or mortar based on renewable raw materials.

Prior Art

The production of concrete and mortar based solely on vegetable aggregates is known, such as, for example, wood, hemp stalk or reed stalk. The chopped plant material is pre-mineralized in a first operating step in the production of such a mortar. In pre-mineralization, plant particles are placed in a mineralization bath or wetted or sprayed with a mineralization liquid, where aluminum sulfate or cement is often used as the mineralizer. The plant particles are subsequently dehydrated and dried. The dried, pre-mineralized particles can then be used as aggregate at the site to mix with cement to form a mortar. The pre-mineralization of the vegetable aggregate ensures a stronger bond between the vegetable aggregate and the cured cement slurry to achieve the desired flexural tensile strength and compressive resistance of the concrete or mortar. In this connection, it should be noted that the pre-mineralization of known vegetable aggregates is expensive and not environmentally friendly.

Old methods for producing concrete or mortar are known, in which unpremineralised vegetable aggregates are mixed with mineral aggregates, mixing water and cement. These methods have not been successful in practice.

FR 1018109(1952) describes a material for sound absorbing floors and partitions, preferably consisting of: 10% artificial cement, 10% ground chalk, 25% sand, 40% sawdust and 10% cork flour. The meaning of artificial cement is not explained in the specification of this patent. In addition, it should be noted that this material contains a total of 35% mineral aggregate and a very small percentage of binder. The patent specification also briefly mentions that its mortar may be produced from cement, chalk, sand and cork only or from cement, chalk, sawdust and cork. Patent specification FR 1018109 does not specify in any further detail about the mixing ratio of the last two mortars.

DE 847725 (1952) describes a material which produces nailed stones (von willben Steinen), lightweight building panels and floor coverings which do not contain water soluble magnesium compounds and which are relatively inexpensive to manufacture. The suggested materials are a mixture of wood flour or chips, limestone or marble dust (particle size 0 to 1mm), and cement. It is recommended to produce nailed stones with a mixture of 2 parts by weight of sawdust or wood chips, 4 parts by weight of ground gray marble and 3 parts by weight of cement. It is suggested to produce a lightweight building panel with a mixture of 3 parts by weight of sawdust mixed with wood shavings or wood shavings mixed with sawdust, 10 parts by weight of ground grey marble and 6 to 7 parts by weight of cement. It is suggested to produce the floor covering with a mixture of 4 parts by weight of wood flour, 12 parts by weight of ground gray marble and 20 parts by weight of cement. When such materials cure, the gray marble and cement form a heavier mineral matrix in which the wood fibers set. It is envisaged that such materials with a heavier mineral matrix do not provide particular thermal and acoustic insulation properties.

GB 638,501(1950) describes a material which is said to be weather resistant, for use in the production of sheet material, roof sheathing, roof tiles, pipes and eave gutters. A preferred mixture of materials comprises 30 parts by weight of paper or cellulose, 40 parts by weight of cement, 10 parts by weight of chalk, 10 parts by weight of slaked lime, 10 parts by weight of river mud. It is envisaged that the material does not provide good thermal and acoustic insulation properties.

WO 9429232 describes a "super-cement". It should ensure an extremely short setting time of concrete and mortar using vegetable aggregates, since its hydration reaction is said not to be affected by contents such as sugars, tanning agents, etc. WO 9429232 does not address the mineralization of the surface of the plant aggregate particles.

Objects of the invention

The object of the present invention is to produce concrete and mortar simply and economically on the basis of vegetable aggregates, the cured concrete/mortar of which should have a low specific weight and, in addition, good properties with respect to thermal insulation, sound insulation, flexural tensile strength and compression resistance.

Summary of the invention

According to the invention, this object is achieved by a process for producing concrete or mortar based solely on vegetable aggregates, mineral binders and mixing water, the vegetable aggregates having a specific gravity, measured at a residual moisture of about 15%, of 80-160kg/m³. The plant aggregate is not pre-mineralized. Instead, 4 to 14kg (typically 6 to 12kg) of non-hydratable, finely ground concrete or mortar are mixedThe mineralizer is added to each cubic meter of the plant aggregate. By "non-hydratable mineralizer" is understood finely ground minerals, and in contrast to binders, which are formed with water for mixing and are not hydrates. It has been demonstrated that the mineralizer added when mixing the concrete/mortar settles on the surface of the vegetable aggregate particles, while at the same time ensuring a stronger bond between the vegetable aggregate particles and the mineral binder matrix when curing it, to achieve the desired flexural tensile strength and compressive resistance of the concrete or mortar. In other words, the plant aggregate surface is said to be pre-mineralized from the beginning of concrete mixing to the end of binder hydration. The finer the mineralizer is ground, the faster and better it settles on the surface of the plant aggregate. It should also be noted that the mineralizer only deposits on the surface of the plant aggregate and therefore does not affect the basic structure of the plant aggregate particles. In addition, the dosage of the mineralizer added should be determined by the type of the plant aggregate, so that it just mineralizes the surface of the plant aggregate particles completely, or only slightly remains. This avoids a greater amount of mineraliser being set between the plant aggregate particles in the binder matrix as the concrete or mortar cures. It was finally verified that the process according to the invention allows a drastic reduction in the production costs of the vegetal aggregates, since it is superfluous to carry out an expensive pre-mineralization in a separate operating step. In addition, the elimination of the pre-mineralization in a separate operation eliminates environmental concerns about the production of concrete and mortar based on vegetable aggregates. The non-vegetable components of the concrete/mortar according to the invention are limited by the mineral binder and the small amount of mineralizer added. Most surprisingly, the cured concrete/mortar nevertheless exhibits superior flexural tensile strength and compressive resistance. The cured concrete/mortar also has a low specific gravity and good properties with respect to thermal and acoustic insulation, due to the high proportions of low specific gravity vegetable aggregates and the mineral binder matrix without other mineral fillers.

Advantageous mineralizers are finely ground stone dust, at least 80% by weight of which have a particle size of less than 0.09 mm. Basically, preferred mineralizers include the raw calcium carbonates that are generally commercially available. The raw calcium carbonate has the advantages of very low cost, high grinding fineness,Can be well suspended in water, and is only 1.18t/m³Low specific gravity of (2). The mixing ratio of mineralizer to mixing water is advantageously from 25 to 50kg mineralizer per 1000kg water.

An advantageous binder is Portland cement, especially PZ 42.5 grade Portland cement. If a plastering mortar is produced, it is advantageous to add hydratable lime, such as hydrated lime, to the portland cement. Depending on the type of mineral binder and the use of the concrete/mortar, between 180 and 400kg of mineral binder are added per cubic meter of vegetable aggregate.

The vegetable aggregate is preferably composed of fibrous particles in the diameter range from 0 to 5.0 mm. If lightweight concrete and lightweight seamless concrete floors are to be produced, it is advantageous if the vegetable aggregate consists for the most part of fibrous particles having a length of 5mm to 40 mm. It is advantageous if lightweight plasters and insulation plasters are to be produced, for example vegetable aggregates consisting for the most part of fibrous particles with a length of less than 5 mm.

The plant aggregate is preferably produced from fibrous, rapidly regrowing plants, for example by shredding. Also considered here are: coniferous trees, hemp stalks, and reed stalks. Broadleaf trees are unsuitable due to their high sugar content. Is mainly C₄Plants of the genus are preferred, which are characterized by a high level of photosynthetic performance. Rapidly growing plants of the genus Miscanthus (Miscanthus) are particularly useful. The preferred Miscanthus type is reed chinese (misanthus giganteus), which has an extremely high silicon content. Which mortar and lightweight concrete produced by the method according to the invention provide, after curing, products with high volume stability.

However, a mixture of different plants may be used as a raw material for the aggregate.

Description of the test

The mortar consisting of the following parts was mixed in a disc mixer:

aggregate：

1m³Comprising 1/3 softwood +13, cutting hemp and 1/3 awn into pieces with the particle diameter of 0-5mm, the particle length of 5-40mm and the residual humidity of less than 18 percent.

Adhesive agent：

280kg of Portland cement (PZ 42.5 grade) and 100kg of hydrated lime.

Mineralizing agent：

9kg of commercially available calcium carbonate, from 95% (raw) CaCO according to the manufacturer₃And 5% other materials, wherein 85% by weight of the particles have a size range between 0mm and 0.09mm, with a maximum super-particle size of 2 mm.

Water for mixing：

250 liters and a temperature of approximately 18 ℃ to reach a consistency of K1 (slightly moist).

In the mixing process, the aggregate material, the mixing water, the binder and the mineralizer are mixed with each other in a forced mixer (e.g., a disk mixer) for 2 minutes. The order of addition is essentially unimportant. However, to avoid blocking and caking of the mixture in the pan mixer, it is advantageous to add the vegetable aggregate and mixing water to the pan mixer before adding the mineralizer and binder.

Mortar mixed according to the above formulation, through the North Rhein-Weist Valley technology university of Gem (Aachen) Germany [ Rheinisch-Westfalische Technischel (RWHH)]Teachers (hereinafter: detection institute) of mechanical engineering and building structures test and pour into steel molds of 40mm x 100mm, slightly tamp and strip. The molded test pieces were set in an air-conditioned room of a detection institute at a temperature of 18 to 20 ℃ for 28 days. The testing college subsequently tested 11 test blocks for their flexural tensile strength and compressive strength according to DIN EN 19604. The arithmetic mean of the 11 test blocks is as follows: bending tensile strength of 3.64N/mm²Compressive property of 9.43N/mm². According to German standard, only 1N/mm is required for plastering mortar²Bending tensile strength and 5N/mm²The compressive property of (2).

Use of concrete or mortar

The concrete or mortar produced by the process according to the invention is outstandingly suitable for producing ecological, heat-insulating lightweight concrete, mortar for internal and external coating, seamless concrete floors or floating seamless concrete floors, and ecological and heat-insulating finished walls, building bricks and insulating panels. These products are not only useful in new ecological buildings, such as single and multi-family homes, but also in repairing existing buildings, such as renovated planking to isolate footfalls, but also have a role in the relatively small self-weight of the finished product (350 kg/m 550kg/m, depending on its composition)³)。

Claims (15)

1. Method for producing concrete or mortar based solely on vegetable aggregates, mineral binders and mixing water, the vegetable aggregates having a specific weight, measured at a residual moisture of 15%, of between 80 and 160kg/m³Characterised in that 4 to 14kg of non-hydrated, finely ground mineralising agent is added per cubic metre of vegetable aggregate when mixing the concrete or mortar, at least 80% by weight of the finely ground mineralising agent having a particle size of less than 0.09 mm.

2. A method of producing concrete or mortar as defined in claim 1, characterised in that the mineralising agent is finely ground stone dust.

3. A method of producing concrete or mortar as defined in claim 1, characterised in that the mineralising agent comprises mainly raw calcium carbonate.

4. A method of producing concrete or mortar as defined in claim 1, wherein the mineral binder comprises portland cement.

5. A method of producing concrete or mortar as defined in claim 1 wherein the portland cement is PZ 42.5 grade portland cement.

6. A method of producing concrete or mortar as defined in claim 1, wherein the mineral binder is a mixture of portland cement and hydrated lime.

7. A method of producing concrete or mortar as defined in claim 1, wherein between 180 and 400kg of mineral binder are added per cubic metre of vegetable aggregate.

8. The method for producing concrete or mortar as defined in claim 1, wherein the mixing ratio of the mineralizer to the mixing water is 25 to 50kg of mineralizer to 1000kg of water.

9. A method of producing concrete or mortar as defined in claim 1, characterized in that the vegetable aggregate consists of fibrous particles having a diameter of less than 5.0 mm.

10. A method for producing concrete or mortar as defined in claim 9, characterized in that lightweight concrete and lightweight seamless concrete floors are produced, the vegetable aggregate of which consists of fibrous particles ranging from 5 to 40mm in length.

11. A method of producing concrete or mortar as defined in claim 9, characterized in that a lightweight mortar and a heat insulating mortar are produced, the vegetable aggregate of which consists of fibrous particles having a length of less than 5 mm.

12. A method of producing concrete or mortar as defined in claim 1, characterized in that coniferous trees, hemp and reeds are used in the production of the vegetable aggregate.

13. A method of producing concrete or mortar as defined in claim 1, wherein miscanthus is used for the production of the plant aggregate.

14. A method of producing concrete or mortar as defined in claim 13, wherein the plant reed chinese is used for the production of the plant aggregate.

15. A method of producing concrete or mortar as defined in any one of claims 1 to 14, characterized in that the method is used for producing lightweight concrete, lightweight mortar, seamless concrete floors and lightweight mortar and heat insulating mortar.