Self-adaptable reaction-powder fibrobeton mixture. Powder high-strength dispersed-reinforced concrete new generation reactive powder concrete Holcim

Dry reaction-powder concrete mixes -

New types of binders for creating

Different types of concrete

Penza State University of Architecture and Construction. Russia

The reaction-powder concrete (RPB) of the new generation is the specific concretes of the future that do not have large-grained and lumpy aggregates. This distinguishes them from fine-grained (sandy) and rubble concrete. The grain composition of the fine-grained sand fraction is very narrow and is in the range of 0.1-0.6 mm. The specific surface area of \u200b\u200bsuch sand (P) does not exceed 400 cm2 / g. The average specific surface area of \u200b\u200bthe fine-dispersed fraction consisting of portland cement (C), stone flour (km) and microcillion (MK), and which is a rheological matrix of RPB, is within a CM2 / g. High dispersion is the basis for the flow of adsorption processes of superplasticizers (SP) and a cardinal decrease in viscosity and yield strength at a minimum of water. Concrete mixtures for such concretes are self-spun when water content is 10-11% of the mass of dry components. In cramped conditions, contact interactions are implemented between particles of components through the thinnest layers of water. In thin layers of water, the reactions of hydration, hydrolysis of cement minerals and the interactions of hydrolysis lime (portland) with microsiness and subtlety particles of silica-containing rocks are intensively proceeded.

Due to the fact that in powder concrete, the volume concentration of cement is 22-25%, then particles of cement, in accordance with the formula proposed earlier, are not in contact with each other, but are separated by nanoscale particles of the microshem, micrometric particles of ground sand and fine-grained sand. In such conditions, in contrast to conventional sandy and crushed stone concrete, the topochemical mechanism of hardening is inferior to an internal, ion-diffusion mechanism of hardening. This is convincingly confirmed by us on simple, but original experiments of monitoring the hardening of composite systems consisting of small amounts of coarse cloths and granulated slags and a significant amount of highly dispersed marble at 10-12% water. In the powder concrete concrete, cement particles are separated by particles of the microcillion and stone flour. Due to the finest shells of water on the surfaces of the particles, the hardening process of powder concrete proceeds is very quickly. The daily strength reaches 40-60 MPa.

We estimate the averaged the thickness of the aqueous cuffs on the dispersed particles of the reaction-powder concrete and compare it with cuffs on cement particles. We will take averaged specific surface area of \u200b\u200bcement 3000 cm2 / g, stone flour - 3800 cm2 / g, microcillion - 3000 cm2 / g. The composition of the dispersed part of the RPB: C - 700 kg; Km - 350 kg; MK - 110 kg. Then the estimated specific surface area of \u200b\u200bthe dispersed part of the powder concrete will be 5800 cm2 / g. The reaction-powder concrete mixtures with hyperplasticizers (GP) acquire gravitational glow at B / T \u003d 0.1. Cement suspension with GP spreads under the action of its own weight at a / c \u003d 0.24.

Then, the averaged thickness of the water layer, distributed on the surface of the particles, is:

Thus, the self-degrees of cement suspension is ensured by almost a fivefold increase in the water layer compared to the RPB mixture. High flow fluidity of reaction-powder concrete mixtures is required to strictly selected granulometry with rheological and active fine-dispersed components in suspensions with a superplasticizer. The content of fine-grained sand fraction 0.14-0.63 mm (average size of 0.38 mm) must ensure that the distance between the particles it was within 55-65 microns. According to foreign researchers de LarRard and F. Sedran, the thickness of the rheological layer (for sands with D \u003d 0.125-0.40) varies from 48 to 88 microns. With such layers, the yield strength defined by us is 5-8 pa.

The disperse part of the reaction-powder concrete consisting of portland cement, stone flour and MK, responsible for the high gravitational fluidity, has extremely high water consumption without adding a joint venture. The composition with the ratio of PC: KM: MK as 1: 0.5: 0.1 The gravitational flow is implemented with a waterway of the attitude equal to 0.72-0.76, depending on the type of MK. The largest water consumption of three studied microcilles - Chelyabinsk, Novokuznetsky and Bratsk has the latter. Its suspension with water begins to spread when the water content is 110% to the mass of MK. Therefore, the presence of only 10% of the brotherly MK increases the water complex of the mixture of cement and ground sand from 34 to 76%. The introduction of the MELFLUX 1641 F Superplasticizer reduces the water content of the dispersed system C + km + MK from 76 to 20% while maintaining the yield. Thus, the water-based effect is 3.8 and reaches a practically four-time reduction in water consumption. It should be noted that none of the studied microcillisms is dispersed in water, and the suspensions are not diluted with any oligomeric first-generation superplasticizers (C-3, Melment, Wiskoment, etc.), no polymeric hyperplasticizers of the second and third generation (Sika Viso Crete , MELFLUX 1641 F, MELFLUX 2641 F). Only in the presence of cement MK becomes a realogically active component. The mechanism of such a transformation associated with the reloading of the negative-charged surfaces of mineral particles cation with calcium hydrolysis lime was revealed by us in 1980. It is the presence of a PC in the presence of the joint venture transforms a water-cement-sandy suspension from the MC to a small-grade and aggregative-stable system.

Dry reaction-powder concrete mixes (SRPSBS) designed to obtain subtleless self-adhesive concrete for monolithic and prefabricated construction, can become a new, main type of composite binder for the production of many types of concrete (drawing). High flow fluidity of reaction-powder concrete mixtures allows you to additionally fill them with rubble while maintaining the yield and use them for self-adjusted high-strength concrete; When filling with sand and rubble - for vibrating technologies of molding, vibropressing and calendering. At the same time, concrete obtained by vibration and vibrous seal technologies may have higher strength than cast concrete. With a higher degree, the 200-B40-B40 classes are obtained.

Fig. 1 main spheres of dry

reaction-powder concrete mixtures

It is safe to assert that in the future, cement binder will be replaced with dry reaction-powder binder (SRPV) based on the following positive factors:

1. Extremely high strength of RPV, reaching 120-160 MPa., Significantly higher than the strength of superplasticized portland cement due to the transformation of "ballast" lime into cementing hydrosilicates.

2. Multifunctionality of the physico-technical properties of concrete when the short dispersed steel fibers is introduced: low water absorption (less than 1%), high frost resistance (more than 1000 cycles), high-strength on axial stretching (10-15 MPa) and bending tensile ( 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 in cement factories, which have a complex of equipment: drying, gross, homogenization, etc.;

4. Wide quartz sand prevalence in many regions of the globe, as well as stone flour from the process of enrichment of ferrous and non-ferrous metals by the methods of magnetic separation and flotation;

5. The huge stocks of sevens of the stone during complex processing of them in fine-grained crushed stone and stone flour;

6. The possibilities of using the co-grinding technology of the reaction filler, cement and superplasticizer;

7. Opportunities for the use of SRPB for the manufacture of high-strength, high-strength crushed stone and sandy concrete new generation, as well as general construction concrete, by varying the ratio of aggregate and binder;

8. Opportunities for obtaining high-strength lightweight concrete on the indissibly micro-deposit - and microelectrics with the implementation of the high strength of the reaction-powder ligament;

9. The possibilities of manufacturing high-strength glue and ligaments for repair work.

The team of the Department "Technology of concrete, ceramics and binders" is not able to develop all the directions indicated in the figure, due to the absence of the necessary conditions, the lack of modern equipment and instruments, financing the most important works, including promising. Judging by publications in Russia, practically not engaged in the development of high-solid reaction-powder concrete concrete classes in 120, in 140. A large number of publications are devoted to the improvement of general binding concrete in order to save cement by 10-20% with the preservation of the same strength.

Over the past five years, publications have been published on the development of classes of classes in 60-B 100 using organ-mineral additives without the use of significant amounts of rheological and reactionary stone flour (dispersed fillers) to increase the volume of the rheological matrix and to enhance the action of superplasticizers and hyperplasticizers new generation. And without it, it is impossible to make self-adverse concrete mixtures with a breaking of a standard cone 70-80 cm. As for the use of nanotechnology, it is not able to radically change the imperfect, the extremely defective structure of concrete classes in 30-B40. Therefore, to achieve high strength equal to 150-200 MPa at the expense of nanotechnology, it is unlikely to succeed in the next 10-15 years. It is necessary to use what lies on the "surface", the fact that the three revolutionary stages is achieved in the chemistry and mechanics of concrete on the evolutionary path of development of its technology. Nanotechnology will be necessary to improve the small-flowered structure of high-strength concrete concrete with an increase in strength of over 200-250 MPa.

The future of concrete is associated with the use of stone flour, for, only the high fluidity of a mixed cement-dispersed matrix, having a 2-3-fold water-based effect, allows to achieve (with the optimal structure of concrete) "high" rheology, and through it the high density and strength of concrete . It is, through a rational rehellion of concrete mixtures, it is necessary to follow the future of concrete, through the creation of rheological matrices of the first and second kind, due to the cardinal change in the formulation and structure of a plasticized concrete mixture. The basic principles of the creation of such concrete and the calculation of their composition are fundamentally different from traditional dense packaging concrete and self-adhesive plasticized concrete concrete with organo-mineral additives.

Literature

1., Kalashnikov high-strength concrete new generation // Popular concrete science. St. Petersburg, №2 (16), 2007. P. 44-49.

2. Kalashnikov Rheological matrices and powder concretes of a new generation. Collection of articles of the International Scientific and Practical Conference "Composite building materials. Theory and practice". Penza. Volga House of Knowledge, 2007. P. 9-18.

3., To the theory of hardening of composite cement binders. Materials of the International Scientific and Technical Conference "Actual Construction Issues". Saransk, Moscow State University, 2004. P. 119-124.

4. DE LARRARD, F. SEDRAN. Optimization of Ultrahight-Performance Concrete by The Use of A Packing Model. Cem Concrete Res. - Vol., 1994. - S.

5 kalashnikov rational rheology into the future of concrete. Part 1. Types of rheological matrices in a concrete mixture, a strategy for increasing concrete strength and saving it in structures // Technology of concrete, No. 5, 2007. S.8-10.

6 Kalashnikov rational rheology into the future of concrete. Part 2. Fine rheological matrices and powder concretes of a new generation // Technology of concrete, No. 6, 2007. P.8-11.

7 Kalashnikov rational rheology into the future of concrete. Part 3. From high-strength and high-strength concrete concretes of the future to superplastic concrete concrete of the present // Technology of concrete, No. 1, 2008. p.22-26

8 Kalashnikov Principles for creating high-strength and high-strength concrete products // Popular concrete science. St. Petersburg. №3, 2008. C.20-22.

9 Kalashnikov compositions of high-strength self-adhesive concrete // Construction materials, No. 10, 2008. C.4-6.

Scientists do not cease to surprise the developments of revolutionary technologies. The mixture with improved properties was obtained not so long ago - in the early 90s of the 20th century. In Russia, its use in the construction of buildings occurs not so often, the main use is the manufacture of bulk floors and decorative products: tabletops, openwork arches and partitions.

Determine the advantages of better quality RPB material will allow the parameters to consider:

Structure.
Properties.
Sphere of use.
Economic substantiation of benefits.

Structure

Concrete - building materials, molded from a compacted mixture of various composition:

1. The basis is a binder, "bonding" filler substance. The property is secure, in a single integer to combine the components ensures the main requirements of the scope of application. Kinds:

Cement.
Gypsum.
Lime.
Polymers.
Bitumen.

2. The aggregate is a component that determines the density, weight, strength. Types and grain size:

Sand - up to 5 mm.
Ceramzit - up to 40.
Slag - up to 15.
Crushed stone - up to 40.

3. Additives - modifiers that improve properties that change the process of setting the resulting mixture. Views:

Plasticizing.
Reinforcing.
Pictory.
Regulatory frost resistance and / or setting speed.

4. Water is a component that reaches the binders (not used in bitumen concrete). The percentage of fluid to the mass of the base determines the plasticity and time of setting, frost resistance and the strength of the product.

The use of various combinations of the foundation, aggregate, additives, their ratios, proportions makes it possible to get concrete with a variety of characteristics.

The difference between the RPB from other types of materials is a small fraction of the aggregate. Reducing the percentage of cement, its replacement of stone flour, microcarcemium made it possible to create mixtures with high fluidity, self-adventure compounds.

Heavy-duty RPB are obtained by mixing water (7-11%) and reactionary active powder. Proportions (%):

Portland cement M500 M500 or white - 30 ~ 34.
Microcardar or stone flour - 12-17%.
Microcarete - 3.2 ~ 6.8.
Thin-grained quartz sand (fraction 0.1 ~ 0.63 mm).
Superplasticizer based on polycarboxylate ether - 0.2 ~ 0.5.
Strength dial accelerator - 0.2.

Technology for receipt:

Components are prepared in accordance with the percentage content.
The mixer serves water and plasticizer. The process of mixing begins.
Cement, stone flour, microsiness are added.
To give color, additive of dyes (iron oxide) is allowed.
Stirring 3 minutes.
Complemented by sand and (for reinforced concrete).
The mixing process is 2-3 minutes. In this time interval, a grapplation accelerator in a percentage ratio of 0.2 of the total mass is introduced.
The surface of the shape is wetted with water.
Plug the mixture.
Sprinkle the surface of the solution distributed in the form.
Cover the injection container.

All operations will be required up to 15 minutes.

Properties of reaction-powder concrete

Positive traits:

1. The use of the microcirem and stone flour led to a decrease in the proportion of cement content and expensive superplasticizers in the RPB, which led to the fall in value.

2. The composition of the self-adhesive powder heavy-duty concrete with a high degree of flow is obtained:

Not necessarily use of vibrationtol.
The facial surface of the products obtained practically does not require mechanical refinement.
The possibility of making elements with different texture and surface roughness.

3. Reinforcement of steel, cellulose fiber, the use of openwork and tissue frames increases the brand to M2000, compressive strength - up to 200 MPa.

4. High resistance to carbonate and sulfate corrosion.

5. The use of the powder reaction mixture helps to create heavy-duty (˃40-50 MPa), lightweight structures (density 1400 ~ 1650 kg / m3). The weight loss reduces the burden on the foundation of structures. Strength allows you to perform carrier elements of the system of a smaller thickness building - reduced consumption.

Characteristics

Engineers at the design stage carry out calculations and make up a number of recommendations and requirements for building materials and parameters. Main factors:

The concrete brand is the number after the letter "M" (M100) in the marking, indicates the range of static load on compression (kg / cm2) after which the destruction occurs.
Strength: compression - fixed with the experimental path the pressure of the press on the sample before its deformation, the unit of measurement: MPa. The bend is the pressure of the press on the center of the sample installed on two supports.
The density is the mass of the volume of 1 cubic meter, a unit of measure: kg / m3.
Frost resistance - the number of freezing cycles and the reverse process with the sample destruction of less than 5%.
Shrinkage ratio is a percentage of volume, linear dimensions of the design by readiness.
Water absorption is the ratio of mass or volume absorbed by a sample of water when immersed in a vessel with liquid. It characterizes the open porosity of concrete.

Scope of application

The new technology based on the reaction-powder mixture allows you to create concrete with improved characteristics and a wide area of \u200b\u200buse:

1. Bulk floors with high abrasion resistance with the minimum thickness of the applied layer.
2. Production of border stone with a long service life.
3. Various supplements in the desired proportion are capable of significantly reduced the water absorption process, which makes it possible to apply the material when erecting marine oil platforms.
4. In civil and industrial construction.
5. Erecting bridges and tunnels.
6. For tabletops with high strength, surface of various structures and roughness.
7. Decorative panels.
8. Creating partitions, artistic products from transparent concrete. With the gradual fill in the form laid photosensitive fibers.
9. Production of architectural thin-walled parts with tissue reinforcement.
10. Use for durable adhesive compositions and repair mixtures.
11. Heat insulating solution using a glass.
12. High strength concrete on granite rubble.
13. Bas-reliefs, monuments.
14. Colored concrete.

Cost

The high price is misleading developers regarding the feasibility of use. Reducing transportation costs, an increase in the life of structures and bulk floors, other positive properties of the material pay off financial investments. Find and buy RPB is quite difficult. The problem is reduced in demand.

Prices for which can be purchased by RPB in Russia:

Unfortunately, it is difficult to bring examples of civil or industrial facilities, erected in Russia with the use of RPB. The main use of powder concrete obtained in the manufacture of artificial stone, countertops, and as well as bulk floors and repair makers.

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