LV14257B - Technological process and device for production of fibroconcrete non-homogeneous structural elements - Google Patents

Abstract

The invention relates to processes for manufacturing monolith and precast fiberconcrete structure elements. The process for manufacturing non-homogeneous fiberconcrete structure elements comprises: preparation of mixture of concrete components - mineral components, water, additives (without fibers), placing it in a mould and its compaction. After that the precise amount of fibers is being uniformly strewn on the upper surface of the concrete and after that the fibers are being pressed into the concrete till the necessary depth. This operation is being carried out by lattice type device having vertical cells, which larger crossection size is being smaller than the length of fiber, and smaller crossection size is being bigger than the largest linear size of the concrete aggregate. Vibration can be applied to the device during the pressing process. According to another embodiment, the device may have parallel strips connected to plane plates or cylindrical shells. In this case fiber pressing into the concrete is being carried out in two mutually perpendicular directions.?

Description

Description of the Invention

The present invention relates to the construction of prefabricated concrete monolithic structures and the manufacture of prefabricated structures. Its use is mainly in building structures that accept both positive and negative bending moment, or where it can be variable, such as floor and foundation slabs.

Fiberglass concrete structures are known in which the fibers are mixed in order to obtain homogeneous distribution and also to obtain the same probability of orientation along all three orthogonal concrete volume coordinates of the building structure / 1, 2 /. Such an even distribution is not rational as it does not correspond to the nature of the main tensile stress distributions, which are never uniform in structure but are highly variable. For curved elements, it changes from zero at the neutral axis to maximum stresses at the cross-sectional edge areas. This means that the fibers near the neutral axis are redundant and their cost to the construction company is a net loss; the amount of these excess fibers can reach 5/6 of all the fibers in the blend.

Fibrobeton SIFCON (Slurry Infiltrated Concrete), which is obtained by filtration of a mixture of fine-grained concrete or cement-sand mortar (3) into a monolithic structure when hardened, is known. This method of producing fibrous concrete can only provide material with a predominantly horizontal plane oriented orientation, but does not allow the distribution of these to be consistent with the tensile stresses in the concrete volume.

There is known a fiber-reinforced concrete building element / 4 / in which the fiber concentration is variable and it is divided by the cross-section of the element depending on the distribution of tensile or compressive stresses. The present invention provides for the concreting of an inhomogeneous fibrobeton concrete element in several layers with different and increasing fiber concentrations in the direction of increasing tensile and / or compressive stresses. Creating such layers in concrete concreting is technologically complex and labor-intensive because it requires each layer to be prepared with a different concrete mixture with a different fiber content, and it is difficult to protect the individual layers from mixing by technological action.

It is therefore an object of the present invention to provide a method of forming an inhomogeneous fibrobeton, which allows the fiber to be placed in curved structural structures at any level that is as close as possible to the principal tensile stress location, without having to separate individual layers of different mixture.

To achieve this goal, a technological process is proposed that includes the following operations:

1. the concrete mixture is laid in a mold or on a subsoil (floors, foundation slabs), sealed by known methods and leveled;

2. Spray the amount of fiber specified in the project on the concrete surface; this operation shall be performed in accordance with the distribution of fibers specified in the design by the surface area of the structure;

3. with the help of a pre-prepared device - horizontal grid - the fibers are pressed from the top into the concrete mixture layer to the level indicated in the project;

4. the grid may vibrate during technological pressings to reduce technological effort;

5. The grid shall be raised, the concrete surface shall be leveled and, if necessary, polished.

The horizontal grid mentioned above is a technological device used to press the fibers into concrete and can be formed in the following ways:

1. In the form of a square cell grid with a diagonal measurement of the pane less than the length of the fibrous material and greater than the maximum dimension of the grain size of the pane;

2. Parallel vertical strips less than the length of the fins; such a grid is simpler to make and easier to clean, and the fibrils are pressed into the concrete by means of two perpendicular directions in each area;

The gratings of technological process and device of claims 5 and 6 may be formed on parallelepiped strips of the cylindrical roller working surface of claim 4, and the strips forming the edge of the grid may be secured parallel to the cylindrical roller bodies and / or guides;

4. each of the technological devices for the construction of fiberglass concrete mentioned in the description of the invention may be equipped with a vibrator.

Comparison of the technological process of the present invention with the construction of inhomogeneous fibrobet concrete structures in today's construction practice is impossible because the authors have failed to find examples of industrial use of inhomogeneous fibrobeton in the publicly available information field. 2 /. The proposed technology allows a fundamental change in the use of fiber concrete, as well as a significant reduction in the cost of expensive fiber. The positive result obtained can also be defined in the opposite way - at the same consumption of fibrils, the invention, compared with the known technologies for the production of fiber concrete, allows to significantly increase the load bearing capacity of the created structures and reduce their volume, mass and construction costs.

Used information sources:

1. Joost C., Walraven, "High Performance Concrete: Developing Remarkable Material." Delft University of Technology, The Netherlands, 2000, GA Delft, Stevinweg 1, 2628 CN.

2. Joost C., Walraven, "High Performance Fiber Reinforced Concrete: Progress in Knowledge and Design Codes." Material and Structures (2009) 42: 1247-1260

3. Adel Mohamed Gilani, "Various Durability Aspects of Slurry Infiltrated Concrete." Thesis Submitted to Graduate School of Natural and Applied Sciences, September 2007.

4. A.Krasnikov, V.A.Lapsa, A.Pupurs Fiberglass Concrete Elements Latvia Patent N ~ 13765.

Claims (8)

Claims 1. A process for forming inhomogeneous fibrous concrete structures, which comprises preparing a concrete mix and incorporating the fibers therein, which comprises mixing the concrete mineral components, water and additives, laying the mixture in a structural mold and sealing it, dosing and uniform application of the fibers. on the upper surface of the concrete and the subsequent penetration of the fibers into the concrete mixture layer perpendicular to the concrete surface with the help of a grid to a certain depth. The process of forming a non-homogeneous fibrous concrete structure according to claim 1, characterized in that the grid vibrates during the application of the fibers in the concrete. A technological device for carrying out the process of forming an inhomogeneous fibrobeton concrete structure according to claim 1 or 2, characterized in that it comprises a cellular lattice with vertical cells, the largest cross-sectional dimension of which is less than the length of the fibers. concrete filler grain size. Technological device for carrying out the process of forming a non-homogeneous fibrobeton concrete structure according to claim 1 or 2, characterized in that it comprises a grid, the grid being formed of and perpendicular to the concrete surface perpendicular and parallel to each other. on bulk grain size. The process of forming an inhomogeneous fibrous concrete structure according to claim 1 or 2, characterized in that the cellular grid is attached to the surface of the cylindrical roller. The technological device according to claim 4 for carrying out the process of forming an inhomogeneous fibrobeton concrete according to claim 5, characterized in that the grid-forming strips are fixed parallel to the cylindrical roller blocks and / or its guide rails. A technological device according to claim 3, 4 or 6 for carrying out the process of forming an inhomogeneous fibrobeton concrete structure according to claim 1 or 2, characterized in that a vibrator is attached thereto. Technological process for forming inhomogeneous fibrobeton concrete structures according to claim 1 or 2, carried out by technological devices according to claim 4 or 6, characterized in that the fibrils are pressed into the concrete mixture in two mutually perpendicular directions.