Manufacture of products from high-strength fiber-reinforced concrete. Powder high-strength dispersion-reinforced concrete of a new generation Various types of concrete

The owners of the patent RU 2531981:

A known method for the manufacture of decorative building products and / or decorative coatings by mixing with water a binder containing Portland cement clinker, a modifier, including an organic water-reducing component and a certain amount of a hardening accelerator and gypsum, pigments, fillers, mineral and chemical (functional) additives, and the resulting mixture stand until saturation of bentonite clay (functional additive mixture stabilizer) with propylene glycol (organic water-reducing component), fixation of the resulting complex with hydroxypropyl cellulose gelling agent, styling, molding, compaction and heat treatment. Moreover, the mixing of dry components and the preparation of the mixture is carried out in different mixers (see RF patent No. 2084416, MPK6 SW 7/52, 1997).

The disadvantage of this solution is the need to use different equipment for mixing the components of the mixture and subsequent compaction operations, which complicates and increases the cost of technology. In addition, when using this method, it is impossible to obtain products with thin and openwork elements.

A known method of preparing a mixture for the production of building products, including activation of the binder by joint grinding of Portland cement clinker with dry superplasticizer and subsequent mixing with filler and water, and first the activated filler is mixed with 5-10% mixing water, then the activated binder is introduced and the mixture is stirred, after which 40 - 60% mixing water is introduced and the mixture is stirred, then the remaining water is introduced and final mixing is carried out until a homogeneous mixture is obtained. Stepwise mixing of the components is carried out for 0.5-1 min. Products made from the resulting mixture must be kept at a temperature of 20°C and a humidity of 100% for 14 days (see RF patent No. 2012551, MPK5 C04B 40/00, 1994).

The disadvantage of the known method is the complex and expensive operation for the joint grinding of the binder and superplasticizer, which requires high costs for the organization of the mixing and grinding complex. In addition, when using this method, it is impossible to obtain products with thin and openwork elements.

Known composition for the preparation of self-compacting concrete, containing:

100 wt. parts of cement

50-200 wt. parts of mixtures of sands from calcined bauxites of different granulometric composition, the finest sand of average granulometric composition is less than 1 mm, the largest sand of average granulometric composition is less than 10 mm;

5-25 wt. parts of ultra-fine particles of calcium carbonate and white soot, and the content of white soot is not more than 15 wt. parts;

0.1-10 wt. parts of a defoamer;

0.1-10 wt. parts of the superplasticizer;

15-24 wt. fiber parts;

10-30 wt. parts of water.

The mass ratio between the amount of ultra-fine particles of calcium carbonate in concrete and the amount of white soot can reach 1:99-99:1, preferably 50:50-99:1 (see RF patent No. 111/62 (2006.01), 2009, para. 12).

The disadvantage of this concrete is the use of expensive calcined bauxite sands, usually used in aluminum production, as well as an excess amount of cement, which leads, respectively, to an increase in the consumption of other very expensive concrete components and, accordingly, to an increase in its cost.

The conducted search showed that no solutions have been found that provide the production of reaction-powder self-compacting concrete.

There is known a method of preparing concrete with the addition of fibers, in which all concrete components are mixed until concrete with the required fluidity is obtained, or dry components are first mixed, such as cement, various types of sand, ultra-fine particles of calcium carbonate, white soot and, possibly, superplasticizer and antifoam agent, after which water is added to the mixture, and, if necessary, a superplasticizer, and an antifoam agent, if present in liquid form, and, if necessary, fibers, and mixed until a concrete with the required fluidity is obtained. After mixing, for example, within 4-16 minutes, the resulting concrete can be easily molded due to its very high fluidity (see RF patent No. ., item 12). This decision was taken as a prototype.

The resulting ultra-high performance self-compacting concrete can be used to make precast elements such as poles, crossbeams, beams, ceilings, tiling, artistic structures, prestressed elements or composite materials, material for sealing gaps between structural elements, elements of sewage systems or in architecture.

The disadvantage of this method is the high consumption of cement for the preparation of 1 m 3 mixture, which entails an increase in the cost of the concrete mixture and products from it due to an increase in the consumption of other components. In addition, the method described in the invention for using the resulting concrete does not carry any information on how, for example, artistic openwork and thin-walled concrete products can be produced.

Widely known methods for the manufacture of various products from concrete, when the concrete poured into the mold is subsequently subjected to vibrocompaction.

However, using such known methods, it is impossible to obtain artistic, openwork and thin-walled concrete products.

A known method for the manufacture of concrete products in packaging forms, which consists in the preparation of a concrete mixture, feeding the mixture into molds, hardening. An air and moisture insulating form is used in the form of packaging thin-walled multi-chamber forms, coated after the mixture is supplied to them with an air and moisture insulating coating. Hardening of products is carried out in sealed chambers for 8-12 hours (see the patent for the invention of Ukraine No. UA 39086, MPK7 V28V 7/11; V28V 7/38; S04V 40/02, 2005).

The disadvantage of the known method is the high cost of the molds used for the manufacture of concrete products, as well as the impossibility of manufacturing artistic, openwork and thin-walled concrete products in this way.

The first task is to obtain the composition of a self-compacting extra-high-strength reaction-powder fiber-reinforced concrete mixture with the required workability and the necessary strength characteristics, which will reduce the cost of the resulting self-compacting concrete mixture.

The second task is to increase the strength characteristics at a daily age with optimal mix workability and improve the decorative properties of the front surfaces of concrete products.

The first task is solved due to the fact that a method has been developed for preparing a self-compacting extra high-strength reaction-powder fiber-reinforced concrete mixture, which consists in mixing the components of the concrete mixture until the required fluidity is obtained, in which the mixing of the components of the fiber-reinforced concrete mixture is carried out sequentially, and initially water and a hyperplasticizer are mixed in the mixer, then cement, microsilica, stone flour are poured and the mixture is stirred for 2-3 minutes, after which sand and fiber are introduced and mixed for 2-3 minutes until a fiber-reinforced concrete mixture is obtained containing components, wt.%:

The total preparation time of the concrete mixture is from 12 to 15 minutes.

The technical result from the use of the invention is to obtain a self-compacting extra high-strength reaction-powder fiber-reinforced concrete mixture with very high flow properties, improving the quality and spreadability of the fiber-reinforced concrete mixture, due to a specially selected composition, sequence of introduction and mixing time of the mixture, which leads to a significant increase in fluidity and strength characteristics concrete up to M1000 and above, reducing the required thickness of products.

Mixing the ingredients in a certain sequence, when initially a measured amount of water and a hyperplasticizer are mixed in the mixer, then cement, microsilica, stone flour are added and mixed for 2-3 minutes, after which sand and fiber are introduced and the resulting concrete mixture is mixed for 2- 3 minutes allows for a significant improvement in the quality and flow characteristics (workability) of the resulting self-compacting extra-high-strength reaction-powder fiber-reinforced concrete mixture.

allows to obtain a self-compacting, extra-high-strength reaction-powder fiber-reinforced concrete mixture with very high flow properties, high strength characteristics and low cost.

The use of the above components, subject to the specified proportion in quantitative ratio, makes it possible to obtain a self-compacting extra high-strength reaction-powder fiber-reinforced concrete mixture with the required fluidity and high strength properties to ensure the low cost of the resulting mixture and thus increase its consumer properties. The use of such components as microsilica, stone flour allows to reduce the percentage of cement, which entails a decrease in the percentage of other expensive components (hyperplasticizer, for example), as well as to abandon the use of expensive sands from calcined bauxites, which also leads to a decrease in the cost of concrete mixture, but does not affect its strength properties.

The second task is solved due to the fact that a method has been developed for manufacturing products in molds from a fiber-reinforced concrete mixture prepared as described above, which consists in feeding the mixture into molds and subsequent holding for curing, and initially a thin layer of water is sprayed onto the inner, working surface of the mold, and after filling the mold with the mixture, a thin layer of water is sprayed on its surface and the mold is covered with a technological pallet.

Moreover, the mixture is fed into the molds sequentially, covering the filled mold from above with a technological pallet, after installing the technological pallet, the process of manufacturing products is repeated many times, placing the next form on the technological pallet above the previous one.

The technical result from the use of the invention is to improve the quality of the front surface of the product, a significant increase in the strength characteristics of the product, due to the use of a self-compacting fiber-reinforced concrete mixture with very high flow properties, special processing of molds and organization of concrete care at a daily age. The organization of concrete care at a daily age consists in ensuring sufficient waterproofing of the molds with concrete poured into them by covering the upper layer of concrete in the mold with a water film and covering the molds with pallets.

The technical result is achieved through the use of a self-compacting fiber-reinforced concrete mixture with very high flow properties, which allows the production of very thin and openwork products of any configuration, repeating any textures and types of surfaces, eliminates the process of vibration compaction when molding products, and also allows the use of any shape (elastic, fiberglass , metal, plastic, etc.) for the production of products.

Pre-wetting the mold with a thin layer of water and the final operation of spraying a thin layer of water on the surface of the poured fiber-reinforced concrete mixture, covering the mold with concrete with the next technological pallet in order to create a sealed chamber for better maturation of the concrete, eliminates the appearance of air pores from trapped air, and achieves high quality of the front surface of the products , reduce the evaporation of water from hardening concrete and increase the strength characteristics of the resulting products.

The number of molds poured simultaneously is selected based on the volume of the obtained self-compacting extra-high-strength reaction-powder fiber-reinforced concrete mixture.

Obtaining a self-compacting fiber-reinforced concrete mixture with very high flow properties and, due to this, with improved workability qualities, makes it possible not to use a vibrating table in the manufacture of artistic products and to simplify the manufacturing technology, while increasing the strength characteristics of artistic concrete products.

The technical result is achieved due to the specially selected composition of the fine-grained self-compacting extra-high-strength reaction-powder fiber-reinforced concrete mixture, the mode of the sequence of introducing the components, the method of processing the molds and organizing the care of concrete at a daily age.

The advantages of this technology and the concrete used:

The use of sand module fineness fr. 0.125-0.63;

The absence of large aggregates in the concrete mix;

The possibility of manufacturing concrete products with thin and openwork elements;

Ideal surface of concrete products;

The possibility of manufacturing products with a given roughness and surface texture;

High grade concrete compressive strength, not less than M1000;

High brand strength of concrete in bending, not less than Ptb100;

The present invention is explained in more detail below with the help of non-restrictive examples.

Fig. 1 (a, b) - scheme for manufacturing products - pouring the resulting fiber-reinforced concrete into molds;

Fig. 2 is a top view of a product obtained using the claimed invention.

The method of obtaining a self-compacting extra high-strength reaction-powder fiber-reinforced concrete mixture with very high flow properties, containing the above components, is carried out as follows.

First, all components of the mixture are weighed. Then, a measured amount of water, a hyperplasticizer, is poured into the mixer. Then the mixer is turned on. In the process of mixing water, hyperplasticizer, the following components of the mixture are sequentially poured: cement, microsilica, stone flour. If necessary, iron oxide pigments can be added to color concrete in mass. After introducing these components into the mixer, the resulting suspension is mixed for 2 to 3 minutes.

At the next stage, sand and fiber are sequentially introduced and the concrete mixture is mixed for 2 to 3 minutes. After that, the concrete mixture is ready for use.

During the preparation of the mixture, an accelerator of curing is introduced.

The resulting self-compacting extra-high-strength reaction-powder fiber-reinforced concrete mixture with very high flow properties is a liquid consistency, one of the indicators of which is the flow of the Hagermann cone on the glass. In order for the mixture to spread well, the spread must be at least 300 mm.

As a result of applying the claimed method, a self-compacting extra-high-strength reaction-powder fiber-reinforced concrete mixture with very high flow properties is obtained, which contains the following components: Portland cement PC500D0, sand fraction from 0.125 to 0.63, hyperplasticizer, fibers, microsilica, stone flour, set accelerator strength and water. When implementing the method for manufacturing a fiber-reinforced concrete mixture, the following ratio of components is observed, wt.%:

Moreover, when implementing the method for manufacturing a fiber-reinforced concrete mix, stone flour is used from various natural materials or wastes, such as, for example, quartz flour, dolomite flour, limestone flour, etc.

The following grades of hyperplasticizer can be used: Sika ViscoCrete, Glenium, etc.

A strength accelerator such as Master X-Seed 100 (X-SEED 100) or similar strength accelerators may be added during the manufacture of the mixture.

The obtained self-compacting extra-high-strength reaction-powder fiber-reinforced concrete mixture with very high flow properties can be used in the production of artistic products with a complex configuration, such as openwork hedges (see Fig. 2). Use the resulting mixture immediately after its manufacture.

A method for manufacturing concrete products from a self-compacting extra-high-strength reaction-powder fiber-reinforced concrete mixture with very high flow properties, obtained by the method described above and having the specified composition, is carried out as follows.

For the manufacture of openwork products by pouring a self-compacting extra-high-strength reaction-powder fiber-reinforced concrete mixture with very high flow properties, elastic (polyurethane, silicone, mold-plastic) or rigid plastic molds are used 1. Conventionally, a mold with a simple configuration is shown, but this type of mold is not indicative and is circuit simplification. The form is installed on the technological pallet 2. A thin layer of water is sprayed onto the inner, working surface 3 of the form, which further reduces the number of trapped air bubbles on the front surface of the concrete product.

After that, the resulting fiber-reinforced concrete mixture 4 is poured into a mold, where it spreads and self-compacts under its own weight, squeezing out the air in it. After the self-levelling of the concrete mixture in the mold, a thin layer of water is sprayed onto the concrete poured into the mold for a more intensive release of air from the concrete mixture. Then the form filled with fiber-reinforced concrete mixture is covered from above with the next technological pallet 2, which creates a closed chamber for more intensive curing of concrete (see figure 1 (a)).

A new mold is placed on this pallet, and the manufacturing process is repeated. Thus, from one portion of the prepared concrete mixture, several molds can be filled sequentially, installed one above the other, which ensures an increase in the efficiency of using the prepared fiber-reinforced concrete mixture. Forms filled with fiber-reinforced concrete mixture are left to cure the mixture for about 15 hours.

After 15 hours, concrete products are demoulded and sent for grinding the back side, and then into a steaming chamber or into a heat-humidity treatment chamber (HMW), where the products are kept until they are fully cured.

The use of the invention makes it possible to produce highly decorative openwork and thin-walled high-strength concrete products of the M1000 and higher grade using a simplified casting technology without the use of vibration compaction.

The invention can be carried out using the listed known components, while observing the quantitative proportions and the described technological regimes. Known equipment can be used in carrying out the invention.

An example of a method for preparing a self-compacting, extra-high-strength reaction-powder fiber-reinforced concrete mixture with very high flow properties.

First, all components of the mixture are weighed and measured in the given amount (wt.%):

Then a measured amount of water and Sika ViscoCrete 20 Gold hyperplasticizer are poured into the mixer. Then the mixer is turned on and the components are mixed. In the process of mixing water and hyperplasticizer, the following components of the mixture are sequentially poured: Portland cement ПЦ500 D0, silica fume, quartz flour. The mixing process is carried out continuously for 2-3 minutes.

At the next stage, sand FR is sequentially introduced. 0.125-0.63 and steel fiber 0.22 × 13mm. The concrete mixture is mixed for 2-3 minutes.

Reducing the mixing time does not make it possible to obtain a homogeneous mixture, and increasing the mixing time does not further improve the quality of the mixture, but delays the process.

After that, the concrete mixture is ready for use.

The total manufacturing time of the fiber-reinforced concrete mixture is from 12 to 15 minutes, this time includes additional operations for backfilling the components.

The prepared self-compacting, extra-high-strength, reaction-powder fiber-reinforced concrete mixture with very high flow properties is used for the manufacture of openwork products by pouring into molds.

Examples of the composition of the obtained self-compacting extra-high-strength reaction-powder fiber-reinforced concrete mixture with very high flow properties, made by the claimed method, are shown in table 1.

1. A method for preparing a self-compacting extra-high-strength reaction-powder fiber-reinforced concrete mixture with very high flow properties, which consists in mixing the components of the concrete mixture until the required fluidity is obtained, characterized in that the mixing of the components of the fiber-reinforced concrete mixture is carried out sequentially, and initially water and a hyperplasticizer are mixed in the mixer, then cement, microsilica, stone flour are poured and the mixture is stirred for 2-3 minutes, after which sand and fiber are introduced and mixed for 2-3 minutes until a fiber-reinforced concrete mixture is obtained, containing, wt.%:

2. The method according to claim 1, characterized in that the total time for preparing the concrete mixture is from 12 to 15 minutes.

3. A method for manufacturing products in molds from a fiber-reinforced concrete mixture prepared by the method according to claims 1, 2, which consists in feeding the mixture into molds and subsequent heat treatment in a steaming chamber, and initially a thin layer of water is sprayed onto the inner, working surface of the mold, after filling the mold with a mixture a thin layer of water is sprayed on its surface and the form is covered with a technological pallet.

4. The method according to claim 3, characterized in that the mixture is fed into the molds sequentially, covering the filled mold from above with a technological pallet, after installing the technological pallet, the process of manufacturing products is repeated many times, placing the next form on the technological pallet above the previous one and filling it.

Similar patents:

The invention relates to the production of building materials and can be used to produce concrete building products subjected to heat and moisture treatment during hardening, for civil and industrial construction.

The invention relates to structural materials and can be used in various industries, such as road and civil engineering. The technical result consists in increasing the crack resistance, strength, resistance of the micro-reinforcing component to the aggressive alkaline environment of the cement stone.

The object of the present invention is a dry binder pre-mix containing in wt.%: Portland cement clinker with a Blaine specific surface area of 4500 to 9500 cm2/g, preferably from 5500 to 8000 cm2/g, while the minimum amount of the mentioned clinker in mass percent relative to the total weight of the preblend is determined by the following formula (I): [-6.10-3×SSBk]+75, in which SSBk is the Blaine specific surface area expressed in cm2/g; fly ash; at least one alkali metal sulfate, wherein the amount of alkali metal sulfate is determined such that the amount of equivalent Na2O in the premixture is greater than or equal to 5 wt.% with respect to the mass of fly ash; at least one source of SO3 in such an amount that the amount of SO3 in the premix is greater than or equal to 2% by weight, based on the weight of the Portland cement clinker; additional materials having a Dv90 less than or equal to 200 μm, which are selected from limestone powders, while the amount of clinker + the amount of fly ash is greater than or equal to 75 wt.%, preferably 78 wt.% in relation to the total mass of the premix; wherein the total amount of clinker in the premix is strictly less than 60% by weight with respect to the total mass of the premix.

The invention relates to the building materials industry. Raw mixture for obtaining artificial rock includes, wt %: Portland cement 26-30, quartz sand 48.44-56.9, water 16-20, fibrous cermet 1.0-1.5, phenylethoxysiloxane 0.06-0.1 .

The invention relates to the building materials industry, in particular to the production of concrete wall blocks. The concrete mixture contains, wt.%: Portland cement 25.0-27.0; characterized by particle size distribution, wt.%: particles larger than 0.63 mm, but smaller than 1 mm - 0.2; larger than 0.315 mm, but smaller than 0.63 mm - 4.8; larger than 0.14 mm, but smaller than 0.315 mm - 62; finer than 0.14 mm - 33 ash and slag filler 15.0-19.0; crushed and sifted through mesh No. 10 slag pumice with a density of 0.4-1.6 g/cm3 30.3-34.3; aluminum powder 0.1-0.2; superplasticizer C-3 0.5-0.6; water 23.0-25.0.

The invention relates to the production of artificial materials imitating natural ones. Raw mixture for the manufacture of a material imitating natural stone, including crushed mica and liquid glass, additionally includes water, white Portland cement, quartz sand, phthalocyanine green pigment or phthalocyanine blue pigment in the following ratio, wt.%: crushed and sifted through mesh No. 5 mica 35.0-40.0, liquid glass 3.0-5.0, water 16.0-18.0, white Portland cement 27.0-31.0, quartz sand 10.7-13.9, phthalocyanine pigment green or phthalocyanine blue pigment 0.1-0.3. // 2530816

The invention relates to the composition of the raw mix for the production of building materials, in particular porous artificial products, and can be used in the manufacture of granular heat-insulating material and extra light aggregate for concrete. Raw mixture for obtaining granulated heat-insulating material contains, wt %: microsilica 33.5-45, ash and slag mixture 3.0-14.5, apatite-nepheline ore enrichment waste 25-30, sodium hydroxide (in terms of Na2O) 22- 27, ammonium bicarbonate 0.5-1.5. The invention is developed in dependent claims. EFFECT: increased strength of granular heat-insulating material while reducing its water absorption, utilization of man-made waste. 3 w.p. f-ly, 1 tab.

The present invention relates to the building materials industry and is used for the manufacture of concrete products: highly artistic openwork fences and gratings, pillars, thin paving slabs and curbstones, thin-walled tiles for internal and external cladding of buildings and structures, decorative products and small architectural forms. The method for preparing a self-compacting extra-high-strength reaction-powder fiber-reinforced concrete mixture consists in sequential mixing of the components until a mixture with the required fluidity is obtained. Initially, water and a hyperplasticizer are mixed in the mixer, then cement, microsilica, stone flour are poured and the mixture is stirred for 2-3 minutes, after which sand and fiber are introduced and mixed for 2-3 minutes. A self-compacting extra-high-strength reaction-powder fiber-reinforced concrete mixture with very high flow properties is obtained, which contains the following components: Portland cement PC500D0, sand fraction from 0.125 to 0.63, hyperplasticizer, fibers, silica fume, stone flour, strength gain accelerator and water. The method for manufacturing concrete products in molds consists in preparing a concrete mixture, feeding the mixture into molds and then holding it in a curing chamber. The inner, working surface of the mold is treated with a thin layer of water, then a self-compacting extra-high-strength reaction-powder fiber-reinforced concrete mixture with very high flow properties is poured into the mold. After filling the mold, a thin layer of water is sprayed onto the surface of the mixture and the mold is covered with a technological pallet. EFFECT: obtaining a self-compacting extra high-strength reaction-powder fiber-reinforced concrete mixture with very high flow properties, high strength characteristics, low cost and making it possible to manufacture openwork products. 2 n. and 2 z.p. f-ly, 1 tab., 3 ill.

CHAPTER 1 MODERN VIEWS AND BASIC

PRINCIPLES OF OBTAINING HIGH-QUALITY POWDER CONCRETE.

1.1 Foreign and domestic experience in the use of high-quality concrete and fiber-reinforced concrete.

1.2 The multicomponent nature of concrete as a factor in ensuring functional properties.

1.3 Motivation for the emergence of high-strength and extra-high-strength reaction-powder concretes and fiber-reinforced concretes.

1.4 High reactivity of dispersed powders is the basis for obtaining high-quality concretes.

CONCLUSIONS ON CHAPTER 1.

CHAPTER 2 INITIAL MATERIALS, RESEARCH METHODS,

INSTRUMENTS AND EQUIPMENT.

2.1 Characteristics of raw materials.

2.2 Research methods, instruments and equipment.

2.2.1 Technology of preparation of raw materials and assessment of their reactive activity.

2.2.2 Technology for the manufacture of powder concrete mixes and me

Tody of their tests.

2.2.3 Research methods. Devices and equipment.

CHAPTER 3 TOPOLOGY OF DISPERSIVE SYSTEMS, DISPERSIVELY

REINFORCED POWDER CONCRETE AND

THE MECHANISM OF THEIR HARDENING.

3.1 Topology of composite binders and mechanism of their hardening.

3.1.1 Structural and topological analysis of composite binders. 59 P 3.1.2 The mechanism of hydration and hardening of composite binders - as a result of the structural topology of the compositions.

3.1.3 Topology of dispersed-reinforced fine-grained concretes.

CONCLUSIONS ON CHAPTER 3.

CHAPTER 4 RHEOLOGICAL STATE OF SUPERPLASTICIZED DISPERSIVE SYSTEMS, POWDER CONCRETE MIXTURES AND THE METHODOLOGY OF ITS EVALUATION.

4.1 Development of a methodology for evaluating the ultimate shear stress and fluidity of dispersed systems and fine-grained powder concrete mixtures.

4.2 Experimental determination of the rheological properties of dispersed systems and fine-grained powder mixtures.

CONCLUSIONS ON CHAPTER 4.

CHAPTER 5 EVALUATION OF REACTIVE ACTIVITY OF ROCKS AND INVESTIGATION OF REACTION POWDER MIXTURES AND CONCRETE.

5.1 Reactivity of rocks mixed with cement.-■.

5.2 Principles for selecting the composition of powder dispersion-reinforced concrete, taking into account the requirements for materials.

5.3 Recipe for fine-grained powder dispersion-reinforced concrete.

5.4 Preparation of concrete mix.

5.5 Influence of compositions of powder concrete mixtures on their properties and axial compressive strength.

5.5.1 Influence of the type of superplasticizers on the spreadability of the concrete mixture and the strength of concrete.

5.5.2 Influence of superplasticizer dosage.

5.5.3 Influence of microsilica dosage.

5.5.4 Influence of the share of basalt and sand on strength.

CONCLUSIONS ON CHAPTER 5.

CHAPTER 6 PHYSICAL AND TECHNICAL PROPERTIES OF CONCRETE AND THEIR

TECHNICAL AND ECONOMIC ASSESSMENT.

6.1 Kinetic features of the formation of the strength of RPB and fibro-RPB.

6.2 Deformative properties of fiber-RPB.

6.3 Volumetric changes in powdered concrete.

6.4 Water absorption of dispersion-reinforced powder concretes.

6.5 Feasibility study and production implementation of the RPM.

Recommended list of dissertations

Composition, topological structure and rheotechnological properties of rheological matrices for the production of new generation concretes 2011, candidate of technical sciences Ananyev, Sergey Viktorovich
Steamed sandy concrete of a new generation on a reaction-powder binder 2013, candidate of technical sciences Valiev, Damir Maratovich
High-strength fine-grained basalt fiber-reinforced concrete 2009, candidate of technical sciences Borovskikh, Igor Viktorovich
Powder-activated high-strength sand concrete and fiber-reinforced concrete with low specific consumption of cement per unit of strength 2012, Candidate of Technical Sciences Volodin, Vladimir Mikhailovich
Powder-activated high-strength concrete and fiber-reinforced concrete with low specific consumption of cement per unit of strength 2011, Ph.D. Khvastunov, Alexey Viktorovich

Introduction to the thesis (part of the abstract) on the topic "Fine-grained reaction-powder dispersed-reinforced concrete using rocks"

Relevance of the topic. Every year in the world practice of concrete and reinforced concrete production, the production of high-quality, high- and extra-high-strength concretes is rapidly increasing, and this progress has become an objective reality, due to significant savings in material and energy resources.

With a significant increase in the compressive strength of concrete, crack resistance inevitably decreases and the risk of brittle fracture of structures increases. Dispersed reinforcement of concrete with fiber eliminates these negative properties, which makes it possible to produce concrete of classes above 80-100 with a strength of 150-200 MPa, which has a new quality - the viscous nature of destruction.

The analysis of scientific works in the field of dispersion-reinforced concretes and their production in domestic practice shows that the main orientation does not pursue the goals of using high-strength matrices in such concretes. The class of dispersion-reinforced concrete in terms of compressive strength remains extremely low and is limited to B30-B50. This does not allow to ensure good adhesion of the fiber to the matrix, to fully use the steel fiber even with low tensile strength. Moreover, in theory, concrete products with freely laid fibers with a degree of volumetric reinforcement of 5-9% are being developed, and in practice, concrete products are produced; they are shed under the influence of vibration with unplasticized "fat" highly shrinkable cement-sand mortars of the composition: cement-sand -1: 0.4 + 1: 2.0 at W / C = 0.4, which is extremely wasteful and repeats the level of work in 1974 Significant scientific achievements in the field of creating superplasticized VNV, microdispersed mixtures with microsilica, with reactive powders from high-strength rocks, made it possible to increase the water-reducing effect to 60% using superplasticizers of oligomeric composition and hyperplasticizers of polymeric composition. These achievements did not become the basis for the creation of high-strength reinforced concrete or fine-grained powder concretes from cast self-compacting mixtures. Meanwhile, advanced countries are actively developing new generations of reaction-powder concretes reinforced with dispersed fibers, woven shed volumetric fine-mesh frames, their combination with rod or rod with dispersed reinforcement.

All this determines the relevance of creating high-strength fine-grained reaction-powder, dispersed-reinforced concrete grades 1000-1500, which are highly economical not only in the construction of responsible unique buildings and structures, but also for general-purpose products and structures.

The dissertation work was carried out in accordance with the programs of the Institute of Building Materials and Structures of the Technical University of Munich (Germany) and the initiative work of the Department of TBKiV PGUAS and the scientific and technical program of the Ministry of Education of Russia "Scientific research of higher education in priority areas of science and technology" under the subprogram "Architecture and construction" 2000-2004

Purpose and objectives of the study. The purpose of the dissertation work is to develop compositions of high-strength fine-grained reaction-powder concretes, including dispersed-reinforced concretes, using crushed rocks.

To achieve this goal, it was necessary to solve a set of the following tasks:

To reveal the theoretical prerequisites and motivations for the creation of multicomponent fine-grained powder concretes with a very dense, high-strength matrix obtained by casting at an ultra-low water content, providing the production of concretes with a ductile character during destruction and high tensile strength in bending;

To reveal the structural topology of composite binders and dispersed-reinforced fine-grained compositions, to obtain mathematical models of their structure for estimating the distances between coarse filler particles and between the geometric centers of reinforcing fibers;

Develop a methodology for assessing the rheological properties of water-dispersed systems, fine-grained powder dispersion-reinforced compositions; to investigate their rheological properties;

To reveal the mechanism of hardening of mixed binders, to study the processes of structure formation;

Establish the necessary fluidity of multicomponent fine-grained powder concrete mixtures, which ensures the filling of molds with a mixture with low viscosity and ultra-low yield strength;

To optimize the compositions of fine-grained dispersed-reinforced concrete mixes with fiber d = 0.1 mm and / = 6 mm with a minimum content sufficient to increase the extensibility of concrete, the preparation technology and establish the effect of the recipe on their fluidity, density, air content, strength and others physical and technical properties of concretes.

Scientific novelty of the work.

1. Scientifically substantiated and experimentally confirmed the possibility of obtaining high-strength fine-grained cement powder concretes, including dispersed-reinforced, made from concrete mixtures without crushed stone with fine fractions of quartz sand, with reactive rock powders and microsilica, with a significant increase the effectiveness of superplasticizers to the water content in the cast self-compacting mixture up to 10-11% (corresponding to semi-dry mixture for pressing without joint venture) of the mass of dry components.

2. Theoretical foundations of methods for determining the yield strength of superplasticized liquid-like disperse systems have been developed and methods for assessing the spreadability of powder concrete mixtures with free spreading and blocked with a mesh fence have been proposed.

3. The topological structure of composite binders and powder concretes, including dispersed reinforced ones, was revealed. Mathematical models of their structure are obtained, which determine the distances between coarse particles and between the geometric centers of fibers in the body of concrete.

4. Theoretically predicted and experimentally proven mainly through the solution diffusion-ion mechanism of hardening of composite cement binders, which increases with the increase in the content of the filler or a significant increase in its dispersion in comparison with the dispersion of cement.

5. The processes of structure formation of fine-grained powder concretes have been studied. It has been shown that powder concretes made from superplasticized cast self-compacting concrete mixtures are much denser, their strength growth kinetics are more intense, and the normative strength is significantly higher than that of concretes without SP, pressed at the same water content under a pressure of 40-50 MPa. Criteria for evaluating the reactive-chemical activity of powders have been developed.

6. The compositions of fine-grained dispersed-reinforced concrete mixes with fine steel fiber 0.15 in diameter and 6 mm long, the technology of their preparation, the sequence of introduction of components and the duration of mixing have been optimized; the influence of the composition on the fluidity, density, air content of concrete mixtures, and compressive strength of concrete has been established.

7. Some physical and technical properties of dispersed-reinforced powder concretes and the main regularities of the influence of various prescription factors on them have been studied.

The practical significance of the work lies in the development of new cast fine-grained powder concrete mixtures with fiber for pouring molds for products and structures, both without and with combined rod reinforcement or without fiber for pouring molds with ready-made volumetric woven fine-mesh frames. With the use of high-density concrete mixtures, it is possible to produce highly crack-resistant bent or compressed reinforced concrete structures with a ductile fracture pattern under the action of ultimate loads.

A high-density, high-strength composite matrix with a compressive strength of 120-150 MPa was obtained to increase adhesion to metal in order to use a thin and short high-strength fiber 0 0.040.15 mm and a length of 6-9 mm, which makes it possible to reduce its consumption and resistance to flow of concrete mixtures for casting technologies for the manufacture of thin-walled filigree products with high tensile strength in bending.

New types of fine-grained powder dispersion-reinforced concretes expand the range of high-strength products and structures for various types of construction.

The raw material base of natural fillers from screenings of stone crushing, dry and wet magnetic separation during the extraction and enrichment of ore and non-metallic minerals has been expanded.

The economic efficiency of the developed concretes consists in a significant reduction in material consumption by reducing the cost of concrete mixtures for the manufacture of high-strength products and structures.

Implementation of research results. The developed compositions have been tested in production at LLC "Penza Concrete Concrete Plant" and at the production base of precast concrete CJSC "Energoservice" and are used in Munich in the manufacture of balcony supports, slabs and other products in housing construction.

Approbation of work. The main provisions and results of the dissertation work were presented and reported at the International and All-Russian scientific and technical conferences: "Young science - the new millennium" (Naberezhnye Chelny, 1996), "Issues of planning and urban development" (Penza, 1996, 1997, 1999 d), “Modern problems of building materials science” (Penza, 1998), “Modern construction” (1998), International scientific and technical conferences “Composite building materials. Theory and practice "(Penza, 2002,

2003, 2004, 2005), “Resource and energy saving as a motivation for creativity in the architectural construction process” (Moscow-Kazan, 2003), “Actual issues of construction” (Saransk, 2004), “New energy and resource-saving high-tech technologies in the production of building materials "(Penza, 2005), the All-Russian scientific and practical conference "Urban planning, reconstruction and engineering support for the sustainable development of cities in the Volga region" (Tolyatti, 2004), Academic readings of the RAASN "Achievements, problems and promising directions development of the theory and practice of building materials science” (Kazan, 2006).

Publications. Based on the results of the research, 27 papers were published (2 papers in journals according to the HAC list).

Structure and scope of work. The dissertation work consists of an introduction, 6 chapters, main conclusions, applications and a list of used literature of 160 titles, presented on 175 pages of typewritten text, contains 64 figures, 33 tables.

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Dissertation conclusion on the topic "Building materials and products", Kalashnikov, Sergey Vladimirovich

1. Analysis of the composition and properties of dispersed reinforced concrete produced in Russia indicates that they do not fully meet the technical and economic requirements due to the low compressive strength of concrete (M 400-600). In such three-, four- and rarely five-component concretes, not only dispersed reinforcement of high strength, but also of ordinary strength, is underused.

2. Based on theoretical ideas about the possibility of achieving maximum water-reducing effects of superplasticizers in dispersed systems that do not contain coarse-grained aggregates, high reactivity of silica fume and rock powders, which jointly enhance the rheological effect of the joint venture, the creation of a seven-component high-strength fine-grained reaction-powder concrete matrix for thin and relatively short dispersed reinforcement d = 0.15-0.20 μm and / = 6 mm, which does not form "hedgehogs" in the manufacture of concrete and slightly reduces the fluidity of PBS.

3. It is shown that the main criterion for obtaining high-density PBS is the high fluidity of a very dense cementing mixture of cement, MK, rock powder and water, provided by the addition of SP. In this regard, a methodology has been developed for assessing the rheological properties of disperse systems and PBS. It has been established that high fluidity of PBS is ensured at a limiting shear stress of 5-10 Pa and a water content of 10-11% of the mass of dry components.

4. The structural topology of composite binders and dispersed-reinforced concretes is revealed and their mathematical models of the structure are given. An ion-diffusion through-mortar mechanism of hardening of composite filled binders has been established. Methods for calculating the average distances between sand particles in PBS, the geometric centers of the fiber in powder concrete are systematized according to various formulas and for various parameters //, /, d. The objectivity of the author's formula is shown in contrast to the traditionally used ones. The optimal distance and thickness of the cementing slurry layer in PBS should be within 37-44 + 43-55 microns at a sand consumption of 950-1000 kg and its fractions of 0.1-0.5 and 0.14-0.63 mm, respectively.

5. The rheotechnological properties of dispersed-reinforced and non-reinforced PBS were established according to the developed methods. Optimal spread of PBS from a cone with dimensions D = 100; d=70; h = 60 mm should be 25-30 cm. The coefficients of decrease in spreading depending on the geometrical parameters of the fiber and the decrease in the flow of PBS when blocking it with a mesh fence were revealed. It is shown that for pouring PBS into molds with volume mesh woven frames, the spread should be at least 28-30 cm.

6. A technique has been developed for assessing the reactive-chemical activity of rock powders in low-cement mixtures (C:P - 1:10) in samples pressed under extrusion molding pressure. It has been established that with the same activity, estimated by strength after 28 days and during long hardening jumps (1-1.5 years), preference when used in RPBS should be given to powders from high-strength rocks: basalt, diabase, dacite, quartz.

7. The processes of structure formation of powder concretes have been studied. It has been established that cast mixtures in the first 10-20 minutes after pouring release up to 40-50% of the entrained air and require coating with a film that prevents the formation of a dense crust. Mixtures begin to actively set 7-10 hours after pouring and gain strength after 1 day 30-40 MPa, after 2 days - 50-60 MPa.

8. The main experimental and theoretical principles for selecting the composition of concrete with a strength of 130-150 MPa are formulated. Quartz sand to ensure high fluidity of PBS should be fine-grained fraction

0.14-0.63 or 0.1-0.5 mm with a bulk density of 1400-1500 kg/m3 at a flow rate of 950-1000 kg/m. The thickness of the interlayer of suspension of cement-stone flour and MF between sand grains should be in the range of 43-55 and 37-44 microns, respectively, with the content of water and SP, providing the spread of mixtures of 2530 cm. The dispersion of PC and stone flour should be approximately the same, the content MK 15-20%, the content of stone flour is 40-55% by weight of cement. When varying the content of these factors, the optimal composition is selected according to the required flow of the mixture and the maximum compressive strength after 2.7 and 28 days.

9. The compositions of fine-grained dispersed-reinforced concretes with a compressive strength of 130-150 MPa were optimized using steel fibers with a reinforcement coefficient // = 1%. Optimal technological parameters have been identified: mixing should be carried out in high-speed mixers of a special design, preferably vacuum-operated; the sequence of loading the components and the modes of mixing, "rest", are strictly regulated.

10. The influence of the composition on the fluidity, density, air content of dispersed-reinforced PBS, on the compressive strength of concrete was studied. It was revealed that the spreadability of mixtures, as well as the strength of concrete, depend on a number of prescription and technological factors. During optimization, mathematical dependences of fluidity, strength on individual, most significant factors were established.

11. Some physical and technical properties of dispersed reinforced concretes have been studied. It is shown that concretes with a compressive strength of 120l

150 MPa have a modulus of elasticity (44-47) -10 MPa, Poisson's ratio -0.31-0.34 (0.17-0.19 - for unreinforced). Air shrinkage of dispersion-reinforced concrete is 1.3-1.5 times lower than that of unreinforced concrete. High frost resistance, low water absorption and air shrinkage testify to the high performance properties of such concretes.

12. Production approbation and feasibility study indicate the need to organize production and widespread introduction of fine-grained reaction-powder dispersed-reinforced concrete into construction.

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Reaction powder concreteREACTION POWDER CONCRETE
New generation reaction-powder concretes (RPCs) are specific concretes of the future, not
having in its composition coarse-grained and lumpy aggregates. This distinguishes them from
fine-grained (sandy) and crushed stone concretes. Dry reaction-powder concrete mixes
(SRPBS), designed to obtain crushed-stone self-compacting concrete for
monolithic and prefabricated construction, can become a new, main type of composite binder
for the production of many types of concrete. High fluidity of reaction-powder concrete mixes
allows you to additionally fill them with crushed stone while maintaining fluidity and use them for
self-compacting high-strength concretes; when filling with sand and gravel - for vibrating
molding, vibropressing and calendering technologies. At the same time, concretes obtained by
vibration and vibro-force compaction technologies, may have higher strength than
cast concrete. At a higher degree, concretes for general construction purposes of classes are obtained
B20-B40.

Reactive powder concrete

REACTION POWDER CONCRETE
Due to the fact that in powder concrete the volume concentration of cement is 22-25%, the particles
cement, in accordance with the previously proposed formula, do not contact each other, but are separated
water nanosized particles of microsilica, micrometric particles of ground sand and
fine grained sand. In such conditions, unlike conventional sandy and crushed stone concrete,
the topochemical mechanism of solidification is inferior to the through-solution, ion-diffusion
hardening mechanism. This is confirmed by simple but original control experiments.
hardening of composite systems consisting of small amounts of coarsely ground clinkers and
granular slag and a significant amount of fine marble at 10-12% water. AT
powdered concrete cement particles are separated by microsilica particles and stone flour.
Due to the thinnest shells of water on the surfaces of particles, the processes of hardening of powder
concrete flows very quickly. Their daily strength reaches 40-60 MPa and more.
The dispersed part of reaction-powder concrete, consisting of Portland cement, stone flour and
MK, responsible for high gravitational fluidity, has a significant water demand
without the addition of SP. With a composition with a ratio of C: KM: MK: Fri as 1: 0.5: 0.1: 1.5, the gravitational current
is implemented at a water-solid ratio equal to 0.095-0.11, depending on the type of MC. the largest
MK has water demand. Its suspension with water begins to spread at a water content of 110-120% by weight of the MC. Only in the presence of cement and SP does MK become a reactive component in an aqueous medium.

binder (SRPV)

ADVANTAGES OF DRY REACTION POWDER
BINDER (SRPV)
1. Extremely high strength RPV, reaching 120-160 MPa., Significantly exceeding
strength of superplasticized Portland cement due to the transformation of "ballast" lime into
cementing hydrosilicates.
2. The multifunctionality of the physical and technical properties of concrete with the introduction of short
dispersed steel fibers: low water absorption (less than 1%), high frost resistance (more
1000 cycles), high axial tensile strength (10-15 MPa) and bending tensile strength (40-50
MPa), high impact strength, high resistance to carbonate and sulfate corrosion, etc.;
3. High technical and economic indicators of the production of SRPB at cement plants,
having a complex of equipment: drying, grinding, homogenization, etc.;
4. The widespread occurrence of quartz sand in many regions of the world, as well as stone
flour from ferrous and non-ferrous metals beneficiation technology by magnetic separation and flotation;

ADVANTAGES OF DRY REACTION POWDER
BINDER (SRPV)
5. Huge reserves of screenings of stone crushing during their complex processing into fine-grained
crushed stone and stone flour;
6. Possibilities of using the technology of joint grinding of the reaction filler, cement and
superplasticizer;
7. Possibilities of using SRPB for the manufacture of high-strength, extra-high-strength
crushed stone and sandy concrete of a new generation, as well as concrete for general construction purposes
by varying the ratio of aggregate and binder;
8. Possibilities of obtaining high-strength lightweight concretes on non-absorbent microglass and
microsolspheres with the implementation of high strength of the reaction-powder binder;
9. Possibilities of manufacturing high-strength adhesive and ligaments for repair work.

(SRPW)

The use of dry reaction-powder binder (RPB)

APPLICATION OF DRY REACTION POWDER BINDER
(SRPW)
Dry reaction-powder concrete mixes (SRPBS) intended for obtaining crushed-stone-free
self-compacting concrete for monolithic and prefabricated construction, can become a new, basic
type of composite binder for the production of many types of concrete. High fluidity
reaction-powder concrete mixes allows you to additionally fill them with crushed stone while maintaining
fluidity and use them for self-compacting high-strength concretes; when filled with sand
crushed stone - for vibration technologies of molding, vibropressing and calendering. Wherein
concretes obtained using vibration and vibro-force compaction technologies may have more
higher strength than cast concrete. At a higher degree, concretes are obtained
general construction purposes of classes B20-B40.
Compressive strength, MPa
Compound
reaction powder
concrete with 0.9% Melflux 2641 F
V/T
0,1
V/C
Consistency
cone blur
0,31
Higermann
290 mm
Raft
Water absorption
o-shchenie
ness
by weight
,
%
kg/m3
2260
0,96
after
steaming
under normal
conditions
hardening
through
1 day
through
28 days
through
1 day
through
28 days
119
149
49,2
132

Efficient use of reaction-powder concrete mix

EFFICIENT USE OF REACTION POWDER
CONCRETE MIXTURE
When filling the reaction-powder concrete mix with sand and high-strength crushed stone,
concrete with a strength of 120-130 MPa with cement costs in terms of heavy concrete equal to 300-350
kg/m3. These are just a few examples of the rational and efficient use of SRPBS. Promising
the possibility of using SRPBS for the manufacture of foam concrete and aerated concrete. They use
portland cement, the strength of which is lower than that of RPB, and the structural processes of self-hardening during
time flows more fully with the latter.
An increase in the operational reliability of products and structures made of such concretes is achieved
dispersed reinforcement with thin short steel fibers, glass and basalt fibers.
This allows you to increase the axial tensile strength by 4-5 times, the tensile strength in bending
6-8 times, impact strength 15-20 times compared to concrete grades 400-500.

This is the advanced concept of the limiting concentration of cement systems with finely dispersed powders from rocks of sedimentary, magmatic and metamorphic origin, selective in terms of high levels of water reduction to SP. The most important results obtained in these works are the possibility of a 5-15-fold reduction in water consumption in dispersions while maintaining gravitational spreadability. It was shown that by combining rheologically active powders with cement, it is possible to enhance the effect of SP and obtain high-density castings.

It is these principles that are implemented in reaction-powder concretes with an increase in their density and strength (Reaktionspulver beton - RPB or Reactive Powder Concrete - RPC [see Dolgopolov N. N., Sukhanov M. A., Efimov S. N. A new type of cement: structure of cement stone. // Building materials. - 1994. - No. 115]). Another result is an increase in the reducing action of the joint venture with an increase in the dispersion of the powders [see. Kalashnikov VI Fundamentals of plasticization of mineral disperse systems for the production of building materials: Dissertation in the form of a scientific report for the degree of Doctor of Science. tech. Sciences. - Voronezh, 1996].

It is also used in powdered fine-grained concretes by increasing the proportion of finely dispersed constituents by adding microsilica to the cement. A novelty in the theory and practice of powdered concrete was the use of fine sand with a fraction of 0.1-0.5 mm, which made the concrete fine-grained, in contrast to ordinary sandy sand with a fraction of 0-5 mm. Our calculation of the average specific surface of the dispersed part of powder concrete (composition: cement - 700 kg; fine sand fr. 0.125-0.63 mm - 950 kg, basalt flour Ssp \u003d 380 m 2 / kg - 350 kg, microsilica Svd \u003d 3200 m 2 /kg - 140kg) with its content of 49% of the total mixture with fine-grained sand of a fraction of 0.125-0.5 mm shows that with a fineness of MK Smk = 3000m 2 /kg, the average surface of the powder part is Svd = 1060m 2 /kg, and with Smk \u003d 2000 m 2 / kg - Svd \u003d 785 m 2 / kg. It is on such finely dispersed components that fine-grained reaction-powder concretes are made, in which the volume concentration of the solid phase without sand reaches 58-64%, and together with sand - 76-77% and is slightly inferior to the concentration of the solid phase in superplasticized heavy concrete (Cv = 0, 80-0.85). However, in crushed concrete, the volume concentration of the solid phase minus crushed stone and sand is much lower, which determines the high density of the dispersed matrix.

High strength is ensured by the presence of not only microsilica or dehydrated kaolin, but also a reactive powder from ground rock. According to the literature, fly ash, baltic, limestone or quartz flour are mainly introduced. Wide opportunities in the production of reactive powder concretes opened up in the USSR and Russia in connection with the development and research of composite binders of low water demand by Yu. M. Bazhenov, Sh. T. Babaev, and A. Komarom. A., Batrakov V. G., Dolgopolov N. N. It was proved that the replacement of cement in the process of grinding VNV with carbonate, granite, quartz flour up to 50% significantly increases the water-reducing effect. The W / T ratio, which ensures the gravitational spreading of crushed stone concrete, is reduced to 13-15% compared to the usual introduction of joint venture, the strength of concrete on such VNV-50 reaches 90-100 MPa. In essence, on the basis of VNV, microsilica, fine sand and dispersed reinforcement, modern powder concretes can be obtained.

Dispersion-reinforced powder concretes are very effective not only for load-bearing structures with combined reinforcement with prestressed reinforcement, but also for the production of very thin-walled, including spatial, architectural details.

According to the latest data, textile reinforcement of structures is possible. It was the development of textile-fiber production of (fabric) three-dimensional frames made of high-strength polymer and alkali-resistant threads in developed foreign countries that was the motivation for the development more than 10 years ago in France and Canada of reaction-powder concretes with joint venture without large aggregates with extra fine quartz aggregate filled with stone powders and microsilica. Concrete mixtures from such fine-grained mixtures spread under the influence of their own weight, filling the completely dense mesh structure of the woven frame and all filigree-shaped interfaces.

"High" rheology of powder concrete mixes (PBS) provides with a water content of 10-12% by weight of dry components the yield strength?0 = 5-15 Pa, i.e. only 5-10 times higher than in oil paints. With this value of ?0, it can be determined using the miniareometric method developed by us in 1995. The low yield point is ensured by the optimal thickness of the rheological matrix interlayer. From the consideration of the topological structure of the PBS, the average thickness of the interlayer X is determined by the formula:

where is the average diameter of sand particles; - volumetric concentration.

For the composition below, with W/T = 0.103, the thickness of the interlayer will be 0.056 mm. De Larrard and Sedran found that for finer sands (d = 0.125-0.4 mm) the thickness varies from 48 to 88 µm.

An increase in the interlayer of particles reduces the viscosity and ultimate shear stress and increases fluidity. Fluidity can be increased by adding water and introducing SP. In general, the effect of water and SP on the change in viscosity, ultimate shear stress, and yield strength is ambiguous (Fig. 1).

Manufacture of products from high-strength fiber-reinforced concrete. Powder high-strength dispersion-reinforced concrete of a new generation Various types of concrete

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