FI103523B - Road construction - Google Patents

Description

1 103523

Road structure - Vägkonstruktion

The invention relates to a road or similar structure according to the preamble of claim 1.

For decades, there have been attempts to find ways to prevent the fracture of road structures and to prevent damage to the structures of the road. To achieve this goal, different types of heat-insulating building materials have been introduced alongside traditional road building materials, sand, gravel and gravel. These include blast furnace slag, polyurethane, rock wool, light gravel and various peat-based thermal insulators. However, the thermal insulation materials used did not fully meet the expectations originally set for them to prevent frost damage.

15 The reasons why the desired result of thermal insulation of road structures has not been achieved have varied widely. Initially, the thermal insulation and wear resistance of the thermal insulation material used may have been insufficient. The thermal insulators are also compressed into time, whereby their thermal insulating capacity is substantially reduced. In many cases, the thermal insulation is incorrectly positioned in the road structure. However, the biggest reason for the inability of heat insulators to prevent the frosting of the road structure has been the proven wetting of the heat insulation.

25 Studies have shown that the thermal conductivity of the building materials used for the construction of the road and the ground under the road increases sharply in the autumn -: in September, October and November. At the same time, the moisture content of the building materials increases. With road construction and ground temperature in the autumn being higher than the ambient air starting materials and the ground beneath the road structure, the building materials release heat. At the same time, the water bound to the subsoil and road building materials is transported as steam towards the colder outdoor air, ie temperature and humidity tend to stabilize. The sealed surface layers of the road prevent water vapor from escaping from the structures of the road into the open air, thereby condensing it into water on the underside of the surface layer. Thus, frost most often occurs on the underside of the dense surface layer.

It is understandable that during this process, the road insulation will also get wet. In other words, water vapor that travels from the land to the structure of the road, especially in the autumn, dampens the structures and, at the same time, the thermal insulation used in the structures. Naturally, wet insulation cannot function as a sufficiently effective frost insulation.

In many cases, the water 15 which has entered the thermal insulation layer has even frozen as the frost has advanced deep enough.

It is an object of the invention to provide a structure of a road or the like in which the above-mentioned wetting of thermal insulation and other structures cannot occur. This object is achieved by a road or a similar structure according to the invention. More particularly, the invention is characterized by what is disclosed in the characterizing part of the appended claim 1.

The invention will now be described in more detail with reference to the accompanying drawing, which shows a 25 road structure according to the invention.

The structural parts of the road are the area structure 1 and the superstructure 2. The substructure 1 refers to the load-bearing road frame located beneath the superstructure 2, i.e., the embankment, the intersection base or the shaped subsoil, with possible drainage or bottom reinforcements. The substructure 1 thus comprises clearing work, bottom reinforcement, and cutting and embankment work. The surface of the substructure 1 is shaped in accordance with building standards 3 103523 with the aim of deflecting water from below the superstructure 2.

By superstructure 2, in road and street building technology, is meant the structure made on the substructure 1.

The superstructure 2 generally has both an upper portion 2a and a lower portion 2b. The support layer of the lower part 2b serves to level the area structure 1 and to form a bearing, correct shape and uniform quality on the upper part 2a. The function of the upper part 2a is to form a bearing surface 10 suitable for traffic. The structure and thickness of the upper portion 2a is generally kept constant over a particular passage, while the structure and thickness of the lower portion 2b may vary depending on the quality of the substructure 1 and the building materials used. The upper part 2a of the superstructure 2 is dimensioned on the basis of the road load-15 aspects. Routing considerations and the expected quality level of the road form the basis for dimensioning the lower part 2b of the superstructure 2. The overall thickness of the superstructure 2 and thus also the thickness of the lower part of the superstructure 2b is determined by the road flatness requirements.

By using thermal insulation 2c, it is possible to reduce the thickness of the superstructure 2 and avoid so-called. transition wedges. use. The superstructures 2 can also be thinned by the use of efficient open ditch or drainage drying and by strengthening the substrate surface, for example by stabilizing. In particular, the thickness of the superstructure 2 of heavily loaded roads to be built on frosty ground is preferably reduced by the use of thermal insulation 2c.

A: The use of thermal insulation 2c is generally intended to improve the thermal insulation performance of a road by about 30% to 35% compared to the thermal insulation performance of a non-isolated 30 road. The thickness of the uninsulated road superstructure 2 in Finland is defined by the so-called frost limit. The frost limit in Finland is approximately 200 cm below the leveling line, below the leveling line 4 103523. Naturally, the altitude of the frost border varies throughout the country. The location of the insulation 2c is determined by the frost limit. The upper surface of the thermal insulation 2c must be above the frost limit at a distance of 5 30% to 35% of the distance between the frost limit and the leveling line. The thickness of the road superstructure 2 can thus be reduced by 30% to 35% compared to the thickness of the uninsulated road superstructure 2. For example, if the frost limit is - 200 cm, the top surface of the insulation is 35% higher than 10, ie - 130 cm. For example, if the thickness of the thermal insulation is 30 cm, the position of the vapor barrier 3 is - 160 cm.

As can be seen from the accompanying drawing, the road structure according to the invention comprises a vapor barrier 3 between the above-mentioned substructure 1 and the superstructure 2. The vapor barrier 3 is directly above the substructure 1, below the thermal insulation layer 2c. In the exemplary case, the surface of the substructure 1 has a drainage layer la on top of the shaped subsoil Ib. In this case, the vapor barrier 3 is mounted on the drainage layer.

20 The vapor barrier 3 is air and waterproof. The structure of the vapor barrier must be impermeable to air and water, so that water vapor from the substructure 1 cannot pass through it. As a vapor barrier 3, a metal plate, a strong plastic film, a filter cloth, or an injectable or moldable elastic mass having excellent wear resistance and resistance to heat fluctuations can be used. The seams of plastic films and filter fabrics should be air and water tight. The metal plates must also be sealed with air and water tightness.

Polyurethane sheets, hard rock wool sheets, maw slag, light gravel, peat peat or hydrophobic peat having a grain size of about 10 mm to 25 mm may be used as heat insulation 2c in connection with the vapor barrier 3. The thermal insulation material 10c23 2c should be made of a material which is highly resistant to compression. The thickness of the thermal insulation layer depends on the ability of the thermal insulation to isolate heat, i.e. the so-called. k value, which varies greatly with different thermal insulation materials.

A protective film 4 made of plastic or filter cloth can be used on the surface of the thermal insulation 2c to prevent mixing of the building materials with no vapor tightness requirements for the protective film 4.

As mentioned above, the surface of the substructure 1 is shaped in accordance with construction standards such that it is possible to drain water from under the superstructure 2. In the invention, the design of the substructure 1 has another meaning. The vapor barrier 3 on top of the ship structure 1 is then in the nominal-15 inclined position. This position allows any water that may have leaked from the road structures above to be drained off the surface of the vapor barrier 3.

The invention is not limited to road structures only, but can also be used in street structures and other building structures that are required .. for non-frosting. The structure of the road or the like may be any thermally insulated structure.

Claims (4)

A road or similar structure, comprising a substructure (1) and a superstructure (2), wherein a thermal insulation (2c) is located in the lower part of the superstructure (2) and a meadow barrier (3) is arranged during the thermal insulation (2c). between the substructure (1) and the superstructure (2), characterized in that the thermal insulation (2c) is essentially composed of hydrophobic peat particles. Road or similar construction according to claim 1, characterized in that the meadow barrier (3) is formed by an air and waterproof metal plate. 15 A road or similar construction according to claim 1, characterized in that the meadow barrier (3) is formed of an air and waterproof film or an air and waterproof fabric, made for example of plastic, or of sprayable or castable, air and waterproof elastic mass. Road or similar construction according to any preceding claim, characterized in that a protective film (4) is arranged above the thermal insulation (2c) to prevent building materials from being mixed.