RU2698112C1 - Method for controlling temperature of the upper layer of road pavement - Google Patents

Abstract

FIELD: technological processes.

SUBSTANCE: method consists in placing a layer of heat-insulating cement concrete under an upper layer of rigid pavement. Layer of heat-insulating cement concrete contains hollow microspheres with coefficient of heat conductivity λ=0.03–0.1 W/m*K and is made in the form of prefabricated plates with compression strength of not less than 25 MPa, in which there are slots of semicircular section for heat exchange elements laying.

EFFECT: preventing slipperiness of road surfaces and protecting them from atmospheric effects.

1 cl, 1 dwg

Description

FIELD OF THE INVENTION

The invention relates to methods and devices for preventing slippage of road surfaces and protecting them from weathering.

State of the art

Pavement construction is known from the prior art, where asphalt concrete is used as the upper (front) layer, laid on top of the underlying (bearing) layer of monolithic or precast concrete. A special case of such a design is a roadway on bridge spans (“Coating on bridges and artificial structures” - Part 6: “Technology for the construction of pavement on a reinforced concrete slab”, NP MOD Soyuzdorstroy, 2013).

The disadvantage of this technical solution is the increased coefficient of linear thermal expansion of asphalt concrete α = 3..7 * 10-5 m / (m * ° C) compared with α = 1 * 10-5 m / (m * ° C) in cement concrete, which leads to the appearance of irreversible deformations in asphalt concrete with daily and seasonal fluctuations in air temperature, as well as under the influence of solar radiation. (Leonovich I.I., Melnikova I.S. "Analysis of the causes of cracks in road surfaces and criteria for their crack resistance". Journal of Construction Science and Technology No. 4-2011, p. 37-41, Minsk, Republic of Belarus).

Also known from the prior art is the construction of pavement containing 2 layers of cement concrete, where the upper (front) layer is, for example, made of concrete of a higher strength class than the underlying layer. A special case of this design is the runway with artificial turf (SP 121.13330.2012 “Aerodromes”, part 7 “Aerodrome coatings”, clause 7.3. “Hard coatings”).

The disadvantage of this technical solution is the increased coefficient of thermal conductivity λ = 2.1 W / m * K of cement concrete in comparison with λ = 0.9 W / m * K of asphalt concrete (V. Blazi. “Designer's reference book. Building physics.” - M .: Technosphere, 2004 .-- p.66). The sliding friction coefficients of the combinations “rubber-concrete” and “rubber-asphalt” are comparable (Kragelsky IV, Vinogradova I.E. “Friction coefficients. Reference manual" M.: Mashgiz, 1962, p.148), i.e. . on a cement concrete sheet of similar roughness icing, dangerous for adhesion to the surface, icing when the air temperature goes over 0 ° C occurs faster than asphalt concrete due to faster cooling of the surface, which requires an increase in the speed and cost of deicing.

The prior art method for regulating the temperature of the roadway, which consists in embedding in its design tubes with heat transfer fluid for heating and cooling or electric heaters (hereinafter heat exchange elements). (V.G. Nikolaev, “Heating and cooling of roads”, the magazine “Building materials, equipment, technologies of the 21st century”, No. 11-2007, p. 34). The purpose of thermal regulation is to control the thermal expansion of asphalt concrete to prevent cracking and increase resource characteristics, as well as protection against the formation of ice on the surface. In the particular case, when arranging two hard layers of pavement, the construction of which is described above, heat-exchange elements can be laid on top of the lower (bearing) layer of reinforced concrete, after which the upper (front) layer is laid - asphalt concrete or cement concrete.

The disadvantage of this technical solution is the high thermal conductivity of the lower layer of reinforced concrete (λ = 2.1 W / m * K), the heating or cooling of which is not useful work (since the heat exchange of the roadway with the environment occurs from top to bottom - from the top layer ) and actually refers to heat loss. So, when using cement concrete as the top layer, the heat transfer rate between the bottom layer and the heat exchange element is equal to the same indicator for the top due to similar heat conductivity coefficients, and when using asphalt concrete with λ = 0.9 W / m * K, it is 2.3 times higher , i.e. we are talking about significant heat loss in the design.

The prior art method for accelerating heat transfer between a heat exchange element and a heated (cooled) medium by placing a heat-insulating material between the heat exchange element (or the medium in which it is located) and the medium that does not require heat transfer. A special case is the “warm floor” technology, where the lower (supporting) layer from the heat exchange element or the medium whose temperature it regulates separates the foam material with λ = 0.03-0.1 W / m * K (XPS, EPP, EPS , PPE ...).

The disadvantage of this technical solution is the low compressive strength of such materials, i.e. they cannot be used to transfer loads between layers in the pavement described above. For example, the compressive strength of one of the most durable Penoplex heat insulators used in construction is 0.5 MPa (TU 5767-006-56925804-2007), while for asphalt concrete this indicator is from 0.8 to 13 , 0 MPa (GOST 9128-2013), and cement concrete - from 25 MPa (GOST 33148-2014).

SUMMARY OF THE INVENTION

The problem to which the claimed method is directed is to increase the heating and cooling efficiency of the upper layer of rigid pavement when using heat-exchange elements.

The technical result of the claimed method is to increase the heat transfer rate between the heat exchange element and the upper layer of rigid pavement in comparison with methods known from the prior art.

The technical result of the claimed method is achieved by placing under the top layer of rigid pavement, inside of which there are heat exchanging elements, a layer of insulating cement concrete with a compressive strength of at least 25 MPa based on hollow microspheres made in the form of prefabricated plates containing semicircular grooves for laying heat exchange elements.

Brief Description of the Drawings

Details, features, as well as advantages of the present method follow from the following description of embodiments of the claimed technical solution using the drawings, which show:

Figure 1 - section of the pavement in which the claimed method is applied.

1 - top layer; 2 - the bottom layer; 3 - a layer of heat-insulating cement concrete; 4 - heat exchange element in a groove of a semicircular section

SUMMARY OF THE INVENTION

The claimed method consists in placing between the upper (1) and lower (2) layers of the pavement a heat-insulating layer (3) of cement concrete based on hollow microspheres, made in the form of pre-made plates with a compressive strength of at least 25 MPa, and containing grooves of a semicircular section for subsequent laying of heat exchange elements (4).

The heat-insulating properties of cement concrete (3) are achieved due to the use of hollow microspheres (aluminum or borosilicate, glass, etc.) as filler, with a low coefficient of thermal conductivity λ = 0.03-0.1 W / m * K, whose influence on the decrease in thermal conductivity of cement concrete while maintaining the strength characteristics, it is proved, for example, in patents RU 2515450, RU 2154619, RU 2355656, as well as in patent RU 176727.

In the claimed method, the minimum sufficient condition is the conformity of the cement concrete used in the insulating (3) layer to the compressive strength class equivalent to that used in the lower (2) layer of the roadway reinforced concrete, B25, or 25 MPa, which follows from paragraph 5.2.5. GOST 33148-2014 “General automobile roads. Reinforced concrete road slabs. Technical requirements".

In the inventive method, slabs of heat-insulating (3) cement concrete are laid on the lower (2) layer using a highly adhesive binder.

The technical result of the claimed invention, which consists in increasing the heat transfer rate between the heat exchange element (4) and the upper (1) layer, is considered achieved, since the thermal conductivity of the heat-insulating layer (3) containing hollow microspheres is in any case lower than that of the lower (2) cement concrete layer. The effective thickness of the heat-insulating layer (3) is determined by calculating the thermal resistances for a particular object, depending on the type and thickness of the upper (1) layer, the power of the heat exchange system (4), climate conditions, etc.

Claims (1)

A method of heating or cooling the upper layer of rigid pavement, comprising placing a layer of heat-insulating cement concrete under it based on hollow microspheres with a thermal conductivity coefficient λ = 0.03-0.1 W / m * K, while the layer of heat-insulating cement concrete is used in the form of plates with strength at compression not less than 25 MPa with grooves of a semicircular section in which heat-exchange elements are laid.

Images