DE202023103900U1 - Fiber concrete product reinforced with chopped basalt fibers coated with underlayer graphene - Google Patents

Abstract

Fiber-reinforced concrete product formed from a mixture of filler, a cement binder, a mineral reinforcing additive with predominantly basalt composition and water, characterized in that the reinforcing additive consists of chopped basalt fibers pre-coated with low-layer graphene.

Description

This utility model relates to the production of building materials, in particular to the production of thin-walled and high-strength concrete products.

The proposed technical solution allows the production of thin-walled high-strength products from fiber concrete, the service life of which does not depend on the ambient humidity. In addition, a fiber-reinforced concrete product reinforced with graphene-coated chopped basalt fibers (carbobasalt) is not subject to chemical corrosion and has hydrophobic properties. Chopped basalt fibers coated with low-layer graphene have high anti-corrosion properties and are resistant to alkalis and acids.

Concrete is known to be a strong but rather brittle material. It is also known that adding a reinforcing component to building materials such as cement products, bricks, asphalt and the like improves the structural integrity of the material and reduces the likelihood of crack formation and opening. The introduction of a discrete reinforcing component into concrete products reduces the effects of two major structural disadvantages: low tensile strength and low elongation at break. This concrete, reinforced with fibers from different origins, was later called fiber concrete.

The appearance of non-structural shrinkage cracks in cement concretes is due to the fact that numerous microcracks form in them during the manufacture of products from cement mortar. Later, when a single or constant load is applied to a product on (from or and on?) a cement binder or under the action of its own mass of such a product, microcracks begin to propagate. Their number and size increases, and they become shrinkage cracks converted into larger non-structural cracks, which lead to a decrease in strength and destruction of the product. Freezing water entering cracks increases the destruction of concrete products.

By preventing the propagation of microcracks, it is possible to increase the effective strength of the product on the cement binder, which leads to an increase in its durability.

The addition of carbobasalt fibers leads to a reduction in cement consumption and therefore a reduction in carbon dioxide emissions into the atmosphere during cement production.

Numerous options for producing high-strength concrete products are known in the prior art.

In particular, numerous studies have been carried out on the modification of concrete with graphene, for example in the work of Al-Shiblawi Karam Ali Hadi “Obtaining graphene-tained suspensions by shear exfoliation of graphite for the modification of construction materials”, Tomsk, 2019. In this work demonstrated that the introduction of graphene suspensions into concrete reduced the water permeability of concrete products by 2.9 times and increased the compressive strength by 1.7-2.5 times.

A number of such products are made from fiber-reinforced concrete with metal fibers, such as in patents: EA201300703, EP 851957 , EP 1282751 , WO84/02732 , US 3942955 , JP 6-294017 .

Products made from such concrete have high mechanical properties, but have one significant disadvantage. Metal fibers corrode over time and no longer fulfill their primary function. In addition, the thinner the metal fiber, the faster it will fail.

To provide additional physical and mechanical strength to a concrete product on a cement binder, various reinforcing components such as metal reinforcement, mineral elements and synthetic fibers are used. At the same time, it is known that synthetic fibers can most effectively prevent the emergence of non-structural shrinkage cracks from microcracks, since they are the thinnest of the listed types of reinforcing components and their dimensions are comparable to those of microcracks.

Technical solutions with synthetic fibers, as in the patents US 6753081 , RU 2074153 , DE202022104639U1 and others described do not allow increasing the strength of fiber-reinforced concrete products to obtain thin-walled products. Synthetic organic fibers do not have good adhesion to cement and have an elastic modulus that is significantly worse than that of mineral fibers and especially basalt fibers.

Concrete products containing basalt fibers have a number of advantages over products containing other types of reinforcing fibers, such as increased abrasion resistance, high splinter and impact resistance, improved sound insulation properties and the ability to shield radiation.

Due to the fact that basalt fibers have practically the same coefficient of thermal expansion as concrete, this circumstance prevents the appearance of cracks during the operation of both large-sized and lumpy products. This increases the tensile strength of products by almost five times and the compressive strength by up to 50%.

The advantages of basalt fiber concrete products are demonstrated in a number of the following patents: WO2022242862A1 , CH709929A1 , EP2336437A1 , DE102010018348A1 and RU123016U1 .

Almost the only disadvantage of fiber-reinforced concrete products based on basalt fibers is their low resistance to alkaline environments. When Portland cement is used as a binder, fiber concrete products are subject to chemical corrosion because strong alkalis are formed when cement is mixed with water, which can destroy basalt fibers.

Protection of basalt fiber reinforcing agent in high-strength fiber-reinforced concrete products is the main task in the technological process of producing such products.

The closest technical solution is the patent DE202023100215U1 , in which the protection of basalt fiber from the effects of an alkaline environment is solved by creating a film structure of organosilicon polymers on the surface of the basalt fiber.

The disadvantages of this technical solution are the adjustment of the technological mode in the production of fiber-reinforced concrete products in comparison with traditional technological operations, as well as insufficient resistance of the concrete product to an alkaline environment during long-term operation in conditions of high humidity.

The aim of the present invention is therefore to create conditions for long-term chemical protection of basalt fibers and to eliminate the shortcomings of the prior art, thereby improving the mechanical properties of fiber concrete. This makes it possible to produce thin-walled concrete products that function in high humidity conditions.

The technical result achieved through the use of the claimed utility model is that the basalt fiber is covered with a layer of low-layer graphene in the process of producing basalt roving by treating the fiber with graphene dispersion. The concentration of graphene dispersion is calculated from the state of formation of graphene particles on the surface of the basalt fiber, mainly in three to five layers, and is about 0.05 - 0.07% of the weight of the basalt fiber.

The number of graphene layers in a low-layer graphene particle is less than 3%. This significantly reduces the opacity of the coating because elemental graphene is converted into nanotubes in less than 2 layers and loses the ability to wrap basalt fibers.

When the number of graphene layers in a multilayer graphene is more than 5, the coating thickness increases and gives the graphene particles excessive rigidity. This does not allow these particles to tightly cover the basalt fiber.

The graphene layer thus formed on the surface of the basalt fiber lies firmly and firmly on the surface of the fibers and is held on the fiber by van der Waals forces.

Due to the layered structure formed on the surface of the basalt fiber, the packing density of all components of the concrete product increases, which gives the product improved performance properties.

The chemical inertness of graphene makes it possible to increase the chemical resistance of the reinforcing component in fiber concrete, which allows the use of fiber concrete products in aggressive environments.

The content of chopped basalt fibers in a fiber-reinforced concrete product in the amount of 0.15 - 0.5% is determined by economic indicators.

In order to compare the mechanical properties of fiber-reinforced concrete products manufactured according to the claimed technical solution and according to the prototype, product samples were prepared and their compressive strength and flexural strength were determined 28 days after the products were formed. The samples were exposed to light at a relative humidity of 75%.

Likewise, the strength properties of the product according to the proposed technical solution and the product manufactured according to the prototype were determined after 28 days at a relative humidity of 100%.

• - Biege- und Druckfestigkeit des erfindungsgemäßen Produkts bei einer relativen Luftfeuchtigkeit von 75 % nach 28 Tagen ist um durchschnittlich 28 % höher als die des Prototyps.
• - Biege- und Druckfestigkeit des erfindungsgemäßen Produkts bei einer relativen Luftfeuchtigkeit von 100 % nach 28 Tagen ist um 50 % höher als die des Prototyps.

The results of the comparison tests showed the following regularity:

• - Flexural and compressive strength of the product according to the invention at a relative humidity of 75% after 28 days is on average 28% higher than that of the prototype.
• - Flexural and compressive strength of the product according to the invention at a relative humidity of 100% after 28 days is 50% higher than that of the prototype.

Based on the data obtained, it can be concluded that the fiber-reinforced concrete product reinforced with chopped basalt fibers (carbobasalt), coated with a layer of graphene according to the proposed technical solution, significantly exceeds the operational characteristics of the product manufactured according to the proposed technical solution prototype.

• 1 den Aufbau eines Faserbetonprodukts mit Basaltfaserverstärkung, wobei:

  1

  Füllkörner,

  2

  Zementbindemittel,

  3

  Basaltfaser mit Graphenbeschichtung sind,

• 2 und 3 eine einzelne Basaltfaser, die mit niedrigschichtigem Graphen beschichtet ist, wobei:

  4

  Basaltfaser mit Graphenbeschichtung,

  5

  Beschichtung von Partikeln aus niedrigschichtigem Graphen auf der Oberfläche der Basaltfaser sind.

The invention will now be explained in more detail with reference to the accompanying drawings. Show it:

• 1 the construction of a fiber concrete product with basalt fiber reinforcement, where:

  1

  filling grains,

  2

  cement binder,

  3

  basalt fiber with graphene coating are,

• 2 and 3 a single basalt fiber coated with low-layer graphene, where:

  4

  basalt fiber with graphene coating,

  5

  Coating of particles of low-layer graphene on the surface of the basalt fiber.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 851957 [0009]
• EP 1282751 [0009]
• WO 8402732 [0009]
• US 3942955 [0009]
• JP 6294017 [0009]
• US 6753081 [0012]
• RU 2074153 [0012]
• DE 202022104639 U1 [0012]
• WO 2022242862 A1 [0015]
• CH 709929 A1 [0015]
• EP 2336437 A1 [0015]
• DE 102010018348 A1 [0015]
• RU 123016 U1 [0015]
• DE 202023100215 U1 [0018]

Claims (6)

Fiber-reinforced concrete product formed from a mixture of filler, a cement binder, a mineral reinforcing additive with predominantly basalt composition and water, characterized in that the reinforcing additive consists of chopped basalt fibers pre-coated with low-layer graphene. Fiber-reinforced concrete product Claim 1 , characterized in that chopped basalt fibers are covered with a multilayer graphene of nanoscale thickness, whose particles consist mainly of 3 - 5 layers of elemental graphene. Fiber concrete product according to the Claims 1 and 2 , characterized in that the chopped basalt fibers are coated with a multilayer graphene layer during the production of the basalt roving. Fiber concrete product according to the Claims 1 and 2 , characterized in that the proportion of chopped basalt fibers coated with low-layer graphene in the fiber concrete is 0.15 - 0.5% by weight. Fiber concrete product Claim 1 , characterized in that it can work under conditions of high humidity and changing temperatures. Fiber concrete product according to the Claims 1 - 4 , characterized in that the process of manufacturing concrete products does not require changes in technological regimes due to the introduction of basalt fibers.

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