RU2783962C1 - Method for manufacturing two-layer bendable elements with an upper layer of high-strength concrete - Google Patents

Abstract

FIELD: construction industry.

SUBSTANCE: invention relates to construction. The method for manufacturing two-layer bendable elements with an upper layer of high-strength concrete includes the alternate formation of individual layers in a horizontal position. At the same time, initially without vibration at a temperature of no more than 20°C, the top layer of the structure is formed from high-strength self-sealing concrete with a setting time of at least 100 minutes. At the second stage, before the first layer begins to set without vibration and pressure, the lower layer of the structure of self-compacting concrete of ordinary strength is laid at a temperature of 25-30°C from the beginning of the formation of the second layer to the moment of demolding.

EFFECT: reduction in the complexity of manufacturing two-layer bendable elements with an upper layer of high-strength concrete and an increase in the strength of the connection of individual layers.

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Description

The invention relates to construction, namely to a method for manufacturing two-layer reinforced concrete bending elements with a top layer of high-strength concrete, and can be used in the construction of residential, industrial buildings and structures for various purposes.

Known methods of manufacturing multilayer reinforced concrete panels No. 2307903 and No. 2154135. A method for manufacturing a three-layer panel No. 2154135 includes the manufacture of extreme and intermediate layers using porous large aggregates and vibration, the formation of the layers is carried out in two stages in a horizontal position, the lower - extreme and heat-insulating layers are made simultaneously from a lightweight concrete mixture delaminated during vibration to form, respectively, a dense and large-porous layers, and the second extreme - upper layer is formed by filling the voids in the upper part of the heat-insulating large-pore concrete under pressure with a mortar with a mobility index of 1-2 cm.

The disadvantages of this method are:

The use of a stratified concrete mixture leads to its stratification into separate elements. Thus, its heaviest components (coarse gravel aggregate) remain at the bottom of the formwork, and the excess water rises to the surface of the layer. Excess water on the contact surface of two layers reduces the physical and mechanical properties of concrete at the place of their conjugation, which in turn reduces the strength of the connection of the layers.

The use of aggregates and devices that create vibration and pressure during compaction of the concrete mixture lowers the level of manufacturability of the method, due to the introduction of additional technological processes, an increase in the mass of the formwork and the involvement of additional personnel.

Lack of regulations for temperature conditions and for the setting time of the mixture. The beginning of the setting of the mixture before the formation of the overlying layer also negatively affects the strength of the connection of the two layers. In view of the fact that an increase in ambient temperature can accelerate the design time for setting the mixture, its value should not go beyond the limit.

The problem to be solved by the invention is to reduce the complexity of manufacturing two-layer bending elements with a top layer of high-strength concrete and to increase the strength of the connection of individual layers.

The problem is solved by the fact that in the method of manufacturing two-layer bending elements with a top layer of high-strength concrete by alternately forming individual layers in a horizontal position, characterized in that initially without vibration at a temperature of not more than 20 ° C, the top layer of the structure is formed from high-strength self-compacting concrete with time setting for at least 100 minutes, at the second stage, before the first layer begins to set, without vibration and pressure, the lower layer of the structure is laid from self-compacting concrete of normal strength, at a temperature of 25-30 ° C from the beginning of the formation of the second layer until the moment of stripping.

The method of manufacturing a two-layer bendable element with a top layer of high-strength concrete is as follows. The formation of the structure occurs in the reverse order, starting from the top layer of high-strength concrete. Freshly prepared, self-compacting high-strength concrete with a setting time of at least 100 minutes is placed without vibration at a temperature not exceeding 20°C. The self-compacting of a high-strength concrete mixture is achieved by introducing fine silica fume aggregate and a superplasticizer with an increased percentage of water reduction into the mixture. The setting time is controlled by introducing hardening retarders into the mixture. At the second stage, before the beginning of the setting of the previous layer, without vibration and pressure application, a freshly prepared, self-compacting concrete mixture of concrete of normal strength is laid at a temperature of 25-30 ° C from the beginning of the formation of the second layer until the moment of stripping. The self-compacting of a mixture of concrete of normal strength is achieved by introducing fine aggregates and superplasticizer into the mixture.

Example. Prepare a concrete mixture of high-strength concrete of the following composition (in wt.%):

Portland cement M 500 - 25%

Quartz sand particle size modulus 2.5-25%

Granite crushed stone fr. 5-10 - 40.88%

Microsilica - 3.6%

Superplasticizer with 40% water reduction 0.72%

Hardening retardant 0.048%

Water 4.752%

The freshly prepared mixture is filled without vibrating into the form. The temperature regime is maintained by air conditioning systems. Prior to the setting of the first layer, a pre-prepared mixture of the second layer of self-compacting concrete is laid.

The formation of the mixture occurs without vibration and pressure. The temperature regime of the second stage is 25-30°C.

Claims (1)

A method for manufacturing two-layer bending elements with a top layer of high-strength concrete by alternately forming individual layers in a horizontal position, characterized in that initially without vibration at a temperature of not more than 20 ° C, the top layer of the structure is formed from high-strength self-compacting concrete with a setting time of at least 100 minutes, at the second stage, before the first layer begins to set, without vibration and pressure, the lower layer of the structure is laid from self-compacting concrete of normal strength at a temperature of 25-30°C from the beginning of the formation of the second layer until the moment of stripping.