RU2585769C1 - Method of forming layers of road pavement of roads and city streets - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to construction of roads and city streets, in particular to system of layers of road pavement and methods of their formation in it. Method of forming layers of road pavement of roads and city streets involves formation of base layer and additional layer with support on underlying ground, top and bottom layers of road surface and layer of wear. Between lower layer of road surface and base of road pavement is transition bearing layer made from elastic waterproof material made from plates made by pressing from fibrous part of plant stems, with their antiseptic properties and impregnated with binding composition to form solid composition.

EFFECT: technical result is upgraded reliability of roads with asphalt coating by avoiding fluidisation of base of road pavement and exclusion of formation of defects on road surface with depth of more than its thickness, due to application of transition of base layer made from elastic waterproof material in system of layers of road pavement.

1 cl, 1 dwg

Description

The invention relates to the field of construction of roads and city streets, in particular to a system of layers of pavement and methods for their formation in it.

It is known that in the General case, the system of layers of pavement may include layers of wear, the upper layer of the road surface, the lower layer of the road surface, the base and an additional layer supported by the underlying soil [1], which can conditionally be taken as an analogue of the proposed technical solution. At the same time, it is customary to subdivide all layer systems as pavement structures according to bending resistance into rigid (cement concrete) and non-rigid, and each of them has a layer serving as a system-forming layer. By type of execution, the layers of pavement come from loose materials, compacted by rollers and the movement of vehicles, gaining strength as a result of compaction and the development of friction forces (splinters) that hold individual particles in the layer; asphalt-concrete and cement-concrete mixtures forming a monolith after laying, compaction and hardening; prefabricated cement concrete slab coatings [1].

Types of road surfaces are regulated in accordance with SNiP 3.06.03-85 “Roads” according to four categories of roads (ie I, II, III and IV), which are arranged taking into account the procedure for reducing operational requirements for them in terms of traffic intensity and vehicle load. Road surfaces, as a rule, belong to the first (I) and (II) categories, i.e. so, for example, with the type of execution for the 1st category of roads: monolithic concrete and precast; asphalt concrete of their hot and warm mixtures; paving of paving stones, mosaics on a stone or concrete base.

During the operation of roads and city streets, defects in the road surface inevitably appear, arising both under the influence of the movement of cars, and under the influence of natural and climatic factors and the initial quality of the materials used and the technology of the road surface.

Practice shows that the greatest number of manifested various types of defects during the operation of roads is observed on roads with non-rigid clothes of their layers, i.e. on roads with asphalt concrete pavement, the number of which in the country is predominant in length.

So the main types of deformation and destruction of pavement of asphalt concrete roads are:

- deformations and destruction caused by reasons that occur in the spring during thawing of the subgrade soil in areas with unfavorable drainage conditions and protection of the subgrade from temperature influences, as well as the use of poor-quality materials and their heterogeneity, poor compaction of the subgrade and road pavement and waterlogging of the subgrade canvases;

- subsidence of non-rigid road pavements in the form of depressions resulting from local subsidence of unconsolidated soil or layers of pavement;

- breach - destruction of pavement in the form of long slots along the wheels;

- chipping - the destruction of the road surface due to the loss of individual grains of gravel and crushed stone material;

- cracks - deformations, usually caused by sharp temperature changes due to insufficient strength of the base or coating;

- potholes - depressions with relatively steep edges resulting from local destruction of the road surface material.

All types of deformations and destruction of the roadway to one extent or another are associated with the manifestation of various kinds of effects, each of which has its own physical nature and mechanism of action on the layers of pavement.

Since in spring, when thawing the soil of the subgrade in areas with unfavorable drainage conditions, stagnant water is retained, which, due to the capillary effect, impregnates the porous structure of the pavement base completely, turning it into a “pseudo-fluid” [2] with a number of negative consequences, t. e. a sharp decrease in the bearing capacity of the roadway; the formation of voids in the base structure due to the arbitrary migration of granules (grains) contained in it; detachment of the road surface from the base under the action of the capillary effect in the zone of their contact.

This, in turn, when the temperature of the air changes from positive to negative, the available water in the voids of the base of the pavement freezes, which leads to an increase in pressure in them and, as a result, cracking in the road surface with the appearance of further related defects, such as depressions, breaks, spalling and potholes.

In addition, periodic impulse effects from the load of the wheels of vehicles on the road surface within the elasticity range create the necessary prerequisites for the appearance of turbulence in the fluidized bed of the pavement, i.e. displacement of its filler.

In this case, increasing the bearing capacity of the asphalt concrete coating by introducing only reinforcing elements in it in the form of asbestos fibers [3] or peat and flax straw [4] does not give the desired result, because the bitumen included in it in a narrow temperature range (from plus to minus) air sharply changes its rheological properties from viscous to fragile state. Therefore, for the system of layers of pavement with an asphalt concrete coating and a base of bulk materials, these drawbacks are, in fact, organically inherent in it, and their elimination requires other systemic technical solutions.

The objective of the invention is to improve the operational properties of roads and streets with asphalt coating by structurally changing layers in the pavement system and the methods of their formation in it.

This is achieved by the fact that in the system of layers of road pavement of roads and city streets, which generally contains a wear layer, an upper pavement layer, a lower pavement layer, a base of bulk materials and an additional layer supported by underlying soil, contains a transition bearing layer as a backbone layer, located between the bottom layer of the road surface and the base of the road pavement of an elastic waterproof material with a given level of operational properties of its elements with structures to the perception of variable power loads and environmental factors acting upon operation and damping, taking into account the relaxation of stresses arising in them. As an elastic waterproof material can be sheets of technical rubber with reinforcement cord as a product of tire recycling; sheets (strips) of polymeric materials reinforced with fibers of mineral materials; multilayer compositions with various fillers, possessing synergism of desired properties. In addition, to solve the problem, it is still necessary to implement a number of technical solutions related to the formation of individual layers of pavement.

So, in this case, the transitional carrier layer of elastic waterproof material in the pavement layer system is formed from plates made by pressing from the fibrous part of plant stems, for example rye and wheat straw, impregnated with an antiseptic and an astringent, for example polyurethane sealant or bitumen mastic, to the formation of a monolithic composition. This method of forming a transitional bearing layer allows directly on the ground to obtain an inexpensive renewable material (resource), year-round in simple production conditions, with low energy costs, with low skilled workers, to conduct, in practice, the mass production of cheap waterproof plates.

Moreover, in order to avoid the negative manifestation of the action of the capillary effect at the base of the pavement, i.e. the possibility of its fluidization, the base layer of the pavement is formed from loose rocky materials with a hydrophobic surface along the width of the carriageway, but not less than half of it on both sides of the curbs in the directions of car traffic.

In fact, the described technical solutions form a system group of inventions aimed at ensuring the operational reliability of the system of layers of pavement.

The implementation of the invention at the systemic level of the formation of the structure of the pavement to achieve a technical result consists in endowing the base of the pavement with hydrophobic properties and placing a separately transitional carrier layer of elastic waterproof material between the pavement layer and the base of the pavement (Fig. 1). For this, the upper layer of the subgrade 1 is carefully compacted and pavement is arranged on it. First, if necessary, an additional layer of base 2 is laid on it, which can be draining, anti-flood, frost-protective. And then base 3 is arranged as the bearing part of the pavement of loose rocky materials with a hydrophobic surface obtained by treating them with, for example, asidol or oleic acid. Then, on the base surface of the pavement, a transitional carrier layer 4 of elastic waterproof material with characteristics depending on the category of roads is laid. The final link in the formation of pavement is that a layer of asphalt mix is laid on the transitional carrier layer 4 to form a pavement 5, followed by compaction with rollers.

In this case, the feasibility and effectiveness of the proposed technical solution is simply and clearly confirmed by physical modeling by the analogy method, consisting in the fact that a plastic sponge was placed on a flat vessel with water h = 10 mm (dimensions: l × b × h = 40 × 40 × 30 mm ) with preliminary impregnation of its upper layer with vegetable oil to a thickness l = 3 mm, and from above it was covered with a sheet of paper with a layer of sodium chloride placed on it. Then, with periodic pressure from above on the sponge through a layer of salt, water from a flat vessel filled the entire volume of the sponge through the capillaries of the sponge to the surface of the oil layer in it, and the salt on it remained dry. It should be noted that when modeling the embodiment of the technical solution by analogy, there was a structural replacement of one layer of pavement with another in the following order: wet soil of the subgrade on a flat vessel with water; the porous structure of the base of the pavement on the sponge with a porous structure; a hydrophobic surface of the base of loose rocky material on the surface of the oil layer of the sponge; a transition layer of pavement of elastic material on a sheet of paper; asphalt concrete pavement on a layer of table salt.

The advantage of the invention is to increase the operational reliability of roads and streets with asphalt concrete coating, achieved, in particular, by: avoiding fluidization of the base of the pavement and, as a result, maintaining its bearing capacity; elimination of the formation of defects on the pavement with a depth greater than its thickness due to the use of a transition carrier layer of an elastic waterproof material, which, if necessary, greatly simplifies road repair.

Information sources

1. Silyanov V.V. Transport and operational qualities of roads and city streets: a textbook for students. higher textbook. institutions / V.V. Silyanov, E.R. Domke. - 3rd ed., Erased. - M.: Publishing Center "Academy", 2009, - 352 p.

2. Polytechnical Dictionary, Ch. ed. I.I. Artobolevsky. - M .: Soviet Encyclopedia, 1976.

3. RF patent for the invention No. 2351561 C2, IPC С04В 26/26, C08L 95/00. - Publ. 04/10/2009. Bull. No. 10.

4. RF patent for the invention No. 2479524 C2, IPC C04B 26/26, C08L 95/00. - Publ. 04/20/2013. Bull. No. 11.

Claims (2)

1. The method of forming layers of pavement of roads and city streets, including the formation of a base layer and an additional layer based on the underlying soil, the upper and lower layers of the road surface and the wear layer, characterized in that between the lower layer of the road surface and the base of the pavement transitional carrier layer of an elastic waterproof material formed from plates made by pressing from the fibrous part of plant stems, endowing them with antiseptic properties and impregnated with an astringent to form a monolithic composition. 2. The method of forming layers of pavement of roads and city streets according to claim 1, characterized in that the base layer in the system of layers of pavement is formed from loose rocky materials with a hydrophobic surface along the width of the carriageway, but not less than half of it on both sides from roadsides in the directions of movement of cars.

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