SU1236081A1 - Method of producing the heating board of forms - Google Patents

Description

The invention relates to construction, namely; heating boards of formwork used in the construction of monolithic reinforced concrete structures in dismountable or slidable formwork.

The purpose of the invention is to increase the service life of the shield due to increased wear resistance.

The essence of the invention lies in the fact that in the manufacture of the heating shield opa., 1kubki roll to the skeleton of the deck with electrodes, on the surface of the deck put conductor nkhiy layer of the following composition, May. including:

Isociapate Psexdo-Fornolimer43-46

A mixture of (p) oligoethy. Penbutylene glycol adipate mol. by weight

2000, (p) 1,4-butadiol and (m) trifunctional oligoethylene glycol with coo m: n: p 1; 2.57: 20 54--57

Soot or carbon black8-10

Graphite90-92

then a protective coating is made of a polymer composition comprising an isocyanate pseudoforpolymer and a mixture of (p) oligo ethylene butylene glycol adapinate with MO,: I. mass 2000, (p) 1,4-butanediol and (m) trifunctional oligoethylene glycol with ratios l; l; p 1: 2.57: 20 in the ratio respectively from 75: 100 to 85: 100.

. In order to control the uniform temperature of the floor, the thickness of the current conductor of the 1st layer in the near-electrode zones is 1.2-1.3 and its thickness in the interelectrode areas.

The drawing shows the shield of the heating formwork and the detail of the coating in the electrode zone, general view.

The formwork heating panel contains a frame 1, a deck 2 made of a dielectric material, for example, wood, electrodes 3 made of copper or brass foil, and a conductive layer 4 made of a composite of r of polyurethane of the specified type filled with soot and graphite. A protective coating 5 of polyurethane of the same nature is located above the conductor of the bed 4, located directly on the deck. The thickness of the conductive layer in the near-electrode zones is 0.26-0.6 mm, in the interelectrode - respectively 0.2-0.5 mm. The thickness of the protective coating 5 depends on the field of application of the shield and may be 1-5 mm.

The technology for making gray formwork boards is as follows.

The deck attached to the frame 1 is cleaned and polished with an electric grinder, then with a heat-resistant

The adhesive is attached to the deck electrodes 3. The spacing of the electrodes 3 is 20-40 cm and depends on the electrical resistivity of the conductive layer, which at a specified ratio of constituent components can be 0.5-1 ohm-cm. Electrical resistivity is determined for each batch of a newly prepared composite.

The conductive layer composition is applied to deck 2 of a spray gun in several layers, depending on the rowed crowboard. The thickening of the conductive layer in the near-electrode zones is carried out by applying additional layers. After pre-exposure in normal mustache. The film is polymerized at 120 ° C for 2 hours during 4 hours. The viscosity of the composition is 12-15 with 10 VZ-4 viscometer and depends on the amount of apeton introduced into it. which can range from 500-560 May. hours at 100 May. including polymer. On top of the conductive layer 4, a protective coating 5 of polyurethane of the same nature is applied, which, when mixed with its components, is a viscous liquid and is able to spread on the surface of Depth 2 with conductive layer 4 and form a coating. After prepolymerization under normal conditions for 24 hours, the coating is heat treated at

within 2 hours

The sheeting and the conductive layer have good adhesion between themselves and from the deck of the shield; moreover, due to the elasticity of polyurethane, these elements are highly resistant to impact, vibration, and other loads, which, in addition to high abrasive wear resistance and lack of adhesion to concrete mixes makes such shields reliable in operation and having an increased service life. The turnover of the proposed heating formwork panels is up to 80 cycles when used in collapsible formwork, and when using such boards in slippings of the first forms, their durability is not less than metal

formwork

The work of the proposed formwork is as follows.

The space between installed in

the working position of the formwork is filled with concrete. The heating elements of the panels are connected to a current source for a voltage of 24-36V and heat treatment of the concrete begins due to the conductive transfer of heat from the surface of the panels. At the indicated voltage, the temperature on the surface of the boards is 60-80 ° C. When using the proposed shields in gliding formwork, the rate of concreting is supported by the heat treatment temperature and the time it takes to build strength with concrete. Preliminary calculations show that with a shield height of 1.1-1.2 m and a temperature on their surface of 70 ° C, the rate of vertical penetration is up to 4.8 m / day.

The polymer composition of the conductive layer is prepared as follows.

The isocyanate pseudoforopolymer (component B) is mixed with the previously prepared mixture (component A) (P) of oligo ethylene butylene glycol adipate with mol. mass 2000, (p) 1,4 butanediol and (m) three-functional oligoethylene glycol with a ratio of 7i; l. –p 1: 2.57: 20. The resulting mixture is dissolved in acetone (500-560 May. Parts), then electrically conductive fillers — carbon black and graphite — are added and mixed.

Examples of the proposed compositions are given in the table.

Component. L 4. Component B 57

46

one

(

3

Technical carbon

Graphite

90

0 5

0

The resistivity of the current conductor of the center layer is respectively 0.5; 0.7; 0.73 ohm cm

The polymeric composition of the protective coating is prepared by analogical transformation of components .4 and B and dissolving the mixture in an acetone solvent to the required viscosity, while the ratio of components A and B when applied to an intermediate coating is, respectively, Examples 1--3 the compositions of the current layer are 75: 100, 85: 100 and 85: 100.

When testing a heating shield, wear resistance is 5. 0.00375 g / cm - wear resistance by change o6iieMa 3.12 mm / cm, tensile strength 26.6 MPa, tear resistance 32 kN; m, hardness but Shore 85.

G1 |) and concreting with the use of heating I1ita formwork made by the proposed method after the first 40 cycles, there is no need to clean igite. The first noticeable damage ob-. The writing layer of the green shield is detected after 120 cycles of concreting, which is caused by the development of microdefects, which are made by ionizing P1tyk and the surface of H1ita during compaction of the concrete mix.

Claims (2)

1. METHOD OF MANUFACTURE THE FORMING SHIELD OF FORMWORK, including attaching to the frame of the deck with electrodes, applying a conductive layer and a protective coating to the deck and curing them, characterized in that, in order to increase the service life of the shield due to increased wear resistance, the conductive layer is applied in the following composition, May. hours: Isocyanate pseudophore gender and measures 43-16 A mixture of (l) oligoet and lenb v t and le ι g l and to about l adaptin with mol. weighing 2 () 00. (/ 7) 1,4 butanediol and (.h) trifunctional oligoethylene glycol at a ratio of .h:, h.-p = 1: 2.57: 20 54-57 Soot or carbon black 8-10 Graphite 90–92a is a protective coating made of a polymer composition comprising an isocyanate pseudo-prepolymer and a mixture of (p} oligoethylene bhylene glycol adapinate with a molar mass of 2000, (π) 1,4-butanediol and (. ") Trifunctional oligoethylene glycol in a ratio of h: p: p— 1: 2.57: 20 in the ratio, respectively, from 75: 100 to 85: 100. 2. The method according to π. 1, characterized in that. that, in order to increase the uniformity of the temperature field, the thickness of the conductive layer in the near-electrode zones is 1.2 - 1.3 of its thickness in the interelectrode zones. a: m