CZ34102U1 - Concrete mixture with return filler admixture - Google Patents

Description

Concrete mixture with return filler admixture

Field of technology

The technical solution relates to a concrete mixture with an admixture of a returnable filler obtained as a by-product in the extraction of dust from aggregates in the production of asphalt mixtures.

Prior art

At present, either power plant fly ash that does not comply with ČSN EN 450-1, finely ground limestone or quarry filler is used as a type I admixture in concrete according to ČSN EN 206 + 1. This is created by suctioning fine particles directly during the production of aggregates.

During the process of production of asphalt mixtures in the asphalt mixture packaging plant, the filler fractions from the used aggregate fractions are sucked out. This extraction is carried out in two places of the asphalt mixture packing plant. The primary suction is performed in a drying drum, where the aggregate is dried and heated to the required temperature. Secondary extraction is performed in the area of hot aggregate sorters in batch packing plants. The aspirated return filler is then stored in a separate insulated silo.

The resulting return filer often finds no further use in the packaging center, because its amount is greater than that which can be technically used in the production of asphalt mixtures and is transported back to the quarries as backfill material, or ends up in landfills.

The essence of the technical solution

The task of the technical solution is to obtain a concrete mixture with a returnable filler from asphalt mixture coating plants, the properties of which comply with the ČSN ΕΝ 12620 + A1 standard, according to Table 1, which shows the drop of the returnable filler on the nets.

Table 1 - Grain size requirements for returnable filler as aggregate

Sieve size in mm Drop in percentage by weight Total range for individual results 2 100 0, 125 85 to 100 0, 063 70 to 100

This is achieved by a concrete mixture with a return filler admixture obtained as a by-product in the extraction of dust from aggregates in the production of asphalt mixtures, the essence of which lies in the fact that it consists of aggregates in amounts of 1400 to 2000 kg / m ³ . mixtures of 15 to 135 kg / m ³ , cement 150 to 450 kg / m ³ , plasticizers 0 to 6 kg / m ³ , aerating additives 0 to 2 kg / m ³ and water 120 to 210 kg / m ³ .

It is preferred that for the production of quality concrete, the returnable filler from the asphalt mixing plant as a concrete admixture has a grain size characterized by a 100% drop on 2 mm screens, a 85 to 100% drop on 0.125 mm screens and a 70 to 100% drop on 0.063 mm screens.

It is advantageous if the concrete produced in this way meets the requirements for concretes of strength class C8 / 10 and higher.

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Example of implementing a technical solution

In order to obtain a suitable return filler, it is necessary to set up the production process of asphalt mixtures in such a way that a return filler of the desired properties is generated during production. To do this, it is necessary to set the correct vacuum when extracting filler fractions from individual aggregate fractions and also to adjust the flaps of the coarse separator during the production of asphalt mixtures, which achieves constant quality of returnable filler, especially its grain size according to Table 1. closed steel silo, where it is protected from external weather conditions. Transport on concrete is realized by means of tank trucks.

After performing initial type tests (TT) of the returnable filler according to the standard ČSN ΕΝ 12620 + A1, the product can be declared according to the regulation of the European Parliament and Council (EU) No. 305/2011, Annex V. according to the following systems of assessment and verification of constancy of performance:

1. System 2+ - Declaration of the performance for the essential characteristics of the construction product by the manufacturer on the basis of following items:

The manufacturer performs:

- determination of the product type on the basis of type testing (including sampling), type calculation, tabular values or descriptive documentation of the product

- production management

- testing of samples taken at the plant in accordance with the prescribed test plan

The notified body for production control certificates shall issue a certificate of conformity of production control on the basis of:

- initial factory inspection and factory production control

- the ongoing surveillance, assessment and evaluation of production control

2. System 4 - Declaration of the performance for the essential characteristics of the construction product by the manufacturer on the basis of following items:

The manufacturer performs:

- determination of the product type on the basis of type examination, type calculation, tabular values or descriptive documentation of the product,

- production management

Notified body:

- No tasks are specified for the notified body

The concrete mix formulation that uses this returnable filler to optimize the concrete mix of strength class C 8/10 and higher, especially in relation to the resulting properties: such as the required amount of fines, pumpability, density, etc. The dosage of returnable filler is in the range 15 to 135 kg, which corresponds to 5 to 30% by weight of cement, which is in an amount of 150 to 450 kg / m ³ . It is also necessary to adjust the type and amount of plasticizer, usually increasing the dose of plasticizer by 10 g / kg of returnable filler. A stabilizer can be used to reduce the bleeding of the concrete. The dose of aggregate in the concrete mixture is in the range of 1400 to 2000 kg / m ³ , aerating additives 0 to 2 kg / m ³ and water 120 to 210 kg / m ³ .

A specific example of implementation for the most used type of concrete C 20/25, the degree of environmental influence

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XC1 is shown in Table 2, which gives an example of dosing components using a filler.

Table No.2 Dosing of concrete mixture components using a filler

Component Margin! dosage in kg / m ^{2 3} Specific case of dosage kg / m ³ cement 150 to 450 260 water 120 to 210 169 aggregates 1400 to 2000 1692 returnable filler 15 to 135 78 plasticizer 0 to 6 3.38 aerating additive 0 to 2 0

Industrial applicability

The concrete mix is suitable for all common concrete structures and thus supports the strategy of the circular economy in the construction industry, which aims at the maximum use of by-products.

The increase in the dose of plasticizer and the possible use of a stabilizer is economically balanced by saving small natural aggregates and possibly by saving fees for landfilling the returnable filler, so the final price of concrete using returnable filler according to the technical solution is not higher than the price of comparable reference concrete. big potential.

Claims (2)

CLAIMS FOR PROTECTION 1. Concrete mixture of strength class 8/10 and higher with admixture of returnable filler formed during the production of asphalt mixtures, characterized in that it consists of aggregate in the amount of 1400 to 2000 kg / m ³ , admixture of returnable filler from asphalt mixture coating plants 15 to 135 kg / m ³ , cement 150 to 450 kg / m ³ , plasticizers 0 to 6 kg / m ³ , aerating additives 0 to 2 kg / m ³ , and water 120 to 210 kg / m ³ . Concrete mixture according to Claim 1, characterized in that the reversible filler from the asphalt mixture coating plant as an admixture for the production of concrete has a grain size characterized by a 100% drop in the mesh 2 mm, 85 to 100% drop on 0.125 mm nets, and 70 to 100% drop on 0.063 mm nets.