RU2593400C2 - Method of making double-layer kauton-concrete girders - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to production of double-layer kauton-concrete girders. Method comprises making concrete of upper layer with frame. After 28 days, after development of concrete strength, kauton bottom layer is made. Contact between layers is strengthened with lugs and cuts. After laying layer of kauton, double-layer element is placed in dry warm-up chamber, where curing process occurs at a temperature of 120±5 °C.

EFFECT: high reliability, durability and strength of beams.

1 cl, 2 tbl, 3 dwg

Description

The modern construction industry and industries that are highly aggressive to traditionally used concrete and steel environments, experience an acute shortage of corrosion-resistant materials that combine high physical, mechanical and chemical properties. One of the ways to ensure the required performance indicators is the use of various types of polymer concrete as the base material of building structures. In Voronezh GASU under the leadership of Professor Potapov Yu.B. a new type of polymer concrete was created - rubber concrete (or kauton reduced), which has favorable physical and mechanical properties, as well as high chemical resistance.

If concrete works well only in compression, then kauton has high compressive and tensile strengths. In two-layer structures, the most valuable properties and advantages of each material are effectively used.

The invention relates to the manufacturing technology of two-layer cut-concrete beams and can be used in industrial and civil engineering.

The aim of the invention is to improve the manufacturing method of two-layer cutout-concrete beams, contributing to increased reliability and increase the service life of buildings and structures operating in conditions of aggressive environmental influences.

The prior art method for the manufacture of building structures containing 2 layers of concrete and polystyrene concrete (No. 2004120950). In addition, there are multilayer elements of beam-slabs, in which the outer layers are made of dense concrete, and the inner layer is made of light concrete (copyright certificate AS No. 80317). In patents RU 2011122840 A and No. 2286249, a method for erecting multi-layer walls of a building is presented, in which the wall panels of the indoor modules and self-supporting external insulated panels are made of two-layer plates with a concrete layer having stiffeners, the cavities between which are filled with a layer of insulation, while the inner surface of the module and the outer surface of the outer panel is made of concrete.

In the manufacture of these beams, the following materials are used:

The composition of the kauton is taken according to the copyright certificate No. SU 1724623 A1:

- low molecular weight cis-butadiene rubber of the SKDN-N brand [TU 38.103515-82] is a liquid product of butadiene polymerization under the action of a catalytic system based on nickel salts and organoaluminum compounds;

- technical sulfur [GOST 127-76] - bright yellow powder with a density of 2070 kg / m ³ , with a melting point 114 ° C;

- vulcanization accelerator - tetramethylthiuramdisulfide (Tiuram-D) [GOST 740-76]. It is a powder of gray-white color, density 1300 ... 1400 kg / m ³ , melting point 140 ... 154 ° С;

- vulcanization activator - zinc oxide ZnO (zinc whitewash grade M-1) [GOST 10262-73]. It is a white powder with a density of 5600 ... 5700 kg / m ³ ;

- calcium oxide CaO - a fine white powder with a density of 2500 ... 2900 kg / m ³ , is used as calcium containing component;

- finely ground mineral filler - fly ash of the Voronezh TPP with a specific surface of 2500 ... 2700 cm ² / g, having the following composition by weight in%: SiO ₂ - 48 ... 52; Al ₂ O ₃ - 18.5 ... 21.5; Fe ₂ O ₃ - 12.5 ... 14.5; CaO - 5.5 ... 5.5; MgO - 2 ... 3; K ₂ O - 1 ... 2; Na ₂ O - 1; S ₂ O ₃ - 0.4 ... 0.3; others - 6 ... 15. The composition of fly ash is constant within the specified limits and meets the requirements of GOST 25818-83;

The composition of the couton is carried out in table 1.

- bar reinforcement of class A500C with a diameter of 12 mm and reinforcing wire of class Bp-I with a diameter of 5 mm;

- Portland cement grade 500 3AO EUROCEMENT group.

- sand and granite crushed stone meeting the requirements of GOST 8267-93.

Concrete adopted class B30. This class is selected from the point of view of the most currently used for load-bearing structures. The composition of concrete of class B30 is presented in table 3. In the selected composition, the ratio B / C = 0.5, which provides sufficient adhesion between the layers in multilayer structures.

The composition of concrete is carried out in table 2.

The manufacture of two-layer elements from concrete and kauton was concluded in two stages. At the first stage, concrete of the upper layer was made, after 28 days, after the concrete had gained strength, the kauton of the lower layer was made by molding it in the formwork on hardened concrete.

Before preparing the concrete mixture, sand and gravel were washed, a mold was prepared (mold preparation consisted in cleaning the working surfaces of material residues and lubricating them with a special compound).

Dosing of sand, gravel, cement and water was carried out on an electronic scale with an accuracy of 0.5 g. Beams were reinforced with welded frames. The longitudinal rods of the frames are made of reinforcement of class A500C, the transverse - of BP-I (Figure 1). To connect the rods used resistance welding. Concrete was prepared in a forced-action concrete mixer for 5 minutes.

The beam reinforcement scheme is shown in figure 1, where 1 is a concrete layer B30; 2 - layer of couton; 3 - longitudinal reinforcement in a compressed zone ϕ12 mm class A500C; 4 - longitudinal reinforcement in the stretched zone ϕ12 mm class A500C; 5 - transverse reinforcement ϕ5 mm class BP-I pitch 50 mm; 6 - the height of the concrete layer; 7 - the height of the cauton layer.

First, the dry components of the concrete mixture were mixed, then mixing was carried out together with water. Next, the concrete mixture was placed in a steel mold, the concrete mixture was compacted on a vibrating platform for 100 ± 30 s. Concrete hardened under normal conditions at a temperature of 20 ... 25 ° C at a humidity of 75 ... 85% with moisture for the first seven days, then in air-dry conditions. After 28 days, after the concrete had set its design strength, we started to manufacture a layer of couton. Formwork for the manufacture of beams is shown in figure 2.

The preparation of the kauton mixture included the following operations: washing the filler, drying the filler and filler, preparing the components of the curing group, dosing the components. Dosing of sand, crushed stone, rubber and components of the curing group and the filler was carried out on an electronic balance with an accuracy of 0.5 g. The components were mixed in a high-speed propeller-type mixer. A polymer binder was prepared by combining liquid rubber of the SKDN-N brand with components of the curing group and dispersed mineral filler with fly ash from the thermal power station. The binder mixing time was 80 s at 1000 rpm. Then, fine and coarse aggregate was introduced into the prepared binder.

A polymer concrete mixture was prepared in the same mixer at a speed of 180 rpm for 200 s. Before laying the kauton mixture in the mold, they cleaned the water film from the surface of the concrete layer, cleaned it with a metal brush to increase the adhesion forces between concrete and kauton. For reliable adhesion between concrete and kauton, two rows of shorts with a diameter of 8 mm and a depth of 15 mm in each layer along the entire length of the element are necessary.

In order to remove moisture, the concrete layers were kept at a temperature of 60 ° C for 8 hours. The prepared mixture was laid in molds and compacted on a standard laboratory vibratory platform. Vibration duration 100 ± 30 s. A sign of sufficient compaction of the kauton mixture is the release of a binder on the surface and the cessation of intense formation of air bubbles. After performing all these operations, the mold with the mixture was placed in a dry heating chamber, where couton solidified at a temperature of 120 ± 5 ° C. The dry heating chamber is shown in figure 3. Given approximately the same coefficients of linear thermal expansion of concrete and kauton, significant internal stresses in the element during heating does not occur.

Demagnetization was carried out after complete polymerization and cooling of the samples.

Information sources

1. Borisov Yu.M. Effective composite materials based on low molecular weight polybutadiene oligomer of mixed microstructure PBN [Text]: Diss. ... cand. tech. Sciences: 05.23.05 / Borisov Yuriy Mihaylovich. - Voronezh, 1998 - 230 s.

2. Nguyen F.Z. Two-layer cutout-concrete flexible elements of building structures [Text]: dis. ... cand. tech. Sciences: 05.23.01 / Nguyen Fan Zui. - Voronezh, 2010 .-- 185 p.

3. Pinaev S.A. Short compressed elements of building structures from an effective composite based on butadiene polymer. [Text]: Diss. ... cand. tech. Sciences: 05.23.01 / Pinaev Sergey Aleksandrovich. - Voronezh, 2001 .-- 191 p.

4. Polikutin A.E. Strength and crack resistance of inclined sections of bent elements of building structures from armocauton [Text]: dis. ... cand. tech. Sciences: 05.23.01 / Polikutin Aleksey Eduardovich. - Voronezh, 2002 .-- 235 p.

5. Potapov Yu.B. Highly effective composites based on liquid rubbers [Text] / B.Yu. Potapov [et al.] // Materials of the international scientific and technical conference (IV Academic readings of the RAASN) “Actual problems of building materials science”: Sat. scientific article. - Penza, 1998 .-- S. 16-17.

6. Potapov Yu.B. Kautons - a new class of corrosion-resistant building materials [Text] / B.Yu. Potapov [et al.] // Building materials of the XXI century. - 2000. - No. 9. - S. 9-10.

7. Chmykhov V. A. Resistance of rubber concrete to the action of aggressive environments [Text]: diss .... Cand. tech. Sciences: 05.23.05 / Chmyhov Vitaliy Aleksandrovich. - Voronezh, 2002 .-- 224 p.

Claims (1)

A method of manufacturing two-layer cutout-concrete beams, in which the upper layer (compressed zone) is made of concrete of class B30, and the lower layer (extended zone) of kauton on rubber of the SKDN-N brand, the reliability of contact between the two layers is ensured by shorts, characterized in that first, the concrete of the upper layer with the frame is made, after 28 days, after the concrete has set strength, the kauton of the lower layer is made by molding it in the formwork on hardened concrete; after laying the kauton layer, the two-layer element is placed in a dry heating chamber, where the vulcanization process occurs at a temperature of 120 ± 5 ° С; in order for the two layers of material to work together, the contact between them is reinforced by shorts and notches.

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