RU2600580C1 - Erection method of road pavement with anchoring of asphalt concrete pavement layers and cement concrete base - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to construction and can be used in construction of new and reconstruction of existing roads and aerodromes. Erection method of road pavement includes arrangement of base layer of cement concrete mixture with creation on its surface of corrugated profile with mesh structure by pressing into layer of not hardened mixture and removal from it of hard discretely located pressing appliances (dies) in the form of inverted truncated circular straight cones or regular pyramids of set process parameters.

EFFECT: technical result is increase in bearing capacity and durability of road pavement.

3 cl, 1 tbl, 2 dwg

Description

The invention relates to the field of transport and can be used in the construction of new and reconstruction of existing roads and airfields.

A known method of erecting pavement, including the device of the base layer of cement concrete mixture, and the subsequent, after a set of its strength (hardening), the device of the coating layer of the asphalt concrete mixture, in which the contact surface of the contacting layers is made straight (Pinus E.R. and other Construction cement-concrete coatings of highways. - M., Higher School, 1975, p. 20, Fig. 1.10).

The disadvantage of this method is the lack of mutual volumetric anchoring of layers of asphalt concrete and cement concrete mixture, which, with a large heterogeneity of strength, deformation, thermophysical and other properties of asphalt concrete and cement concrete, creates conditions for the separate operation of the layers of pavement, reduces the energy resource of its joint opposition to operational factors, and, as a result, to premature deformation of pavement in the form of rutting, subsidence, t Eshina and other defects.

The closest to the invention in terms of technical nature and the achieved result is a method of erecting pavement with anchoring layers of asphalt concrete and cement concrete mixture, including arranging a layer of cement concrete mixture, creating a corrugated surface after milling the concrete with milling of the depths of grooves and the width of the undulation, respectively : half and one diameter of the maximum grain aggregate of the asphalt mix and the subsequent device layer of asphalt mixtures (Austrian Patent N AT 405849 B. E01C 7/35).

The disadvantages of the method are the low bearing capacity and durability of the pavement, which is due to the low efficiency of the anchoring layers, as well as high energy consumption, material consumption and the cost of implementing the method.

So, when excavating by milling the base layer of hardened concrete, along with an obvious decrease in the potential energy of pavement, high-quality anchoring of the base with a layer of asphalt concrete coating, due to the impossibility of mutual volumetric penetration of the layer material, as well as low contact adhesion strength of the layer of asphalt concrete mixture with a milled surface of the recesses of the cement concrete layer cannot be provided.

In addition, the shape and dimensions of the corrugated profile on the cement concrete layer, which are provided for layer anchoring by partially placing the largest aggregate grains of the asphalt concrete mixture in them, rather than volumetric layer rooting of the asphalt concrete mixture, also cannot ensure the reliability of the layers working together, since In this case, under the influence of the transport load and a change in air temperature, favorable conditions are created for the concentration of high destructive aggregates in the anchored grains tensile and shear stresses, which in the mixture have the greatest brittleness and the lowest tensile strength.

In addition, the device of waviness on the surface of the concrete layer in the form of volumetric profiles of various cross sections, open in the longitudinal direction, due to the lack of anchoring of the layer of asphalt concrete with a layer of cement concrete in the longitudinal direction, cannot ensure its operational stability and durability from temperature impacts and effects of traffic load.

The disadvantages of this method also include the low adhesive strength of the adhesion of the layers, which is achieved mainly due to the mechanical adhesion of the asphalt mixture with the base layer of the hardened cement concrete mixture by developing its contact surface, which without creating an additional integrating layer between the layers at the stage of formation of the anchored structure of materials from asphalt and cement concrete cannot fully provide an increase in the resource of joint work of layers of pavement in ex operational conditions, i.e. its longevity.

Finally, the disadvantages of this method include the need for additional work to take care of the hardening of the concrete mixture in the period from the moment of its laying to the coating device from the asphalt concrete mixture, which requires interruption in traffic and increases the cost of work.

The problem to which the invention is directed, is to increase the bearing capacity and durability of pavement. Energy consumption, material consumption and the cost of its construction are also reduced.

The essence of the claimed invention lies in the fact that the method of erecting pavement with anchoring layers of cement concrete and asphalt concrete mixtures, including the device of the base layer of cement concrete mixture, creating on its surface after hardening the mixture by milling a wavy profile from longitudinal recesses with a width and depth equal respectively: the diameter of the maximum grain aggregate of the asphalt mix and its half and the subsequent arrangement of the coating layer of the asphalt mix differs it that the creation of corrugated honeycomb structure operate in unsolidified cement concrete mixture by pressing the bed, and extraction therefrom rigid discretely spaced pinch devices (dies) in the form of inverted truncated straight circular cones or pyramids correct, the process parameters are set under the following conditions:

;

;

;

,

;

;

;

,

where h _z - the height of the pressing device (stamp) - the depth of the anchoring of the asphalt mixture, cm;

h ₀ - the thickness of the base layer of cement concrete mixture, cm;

d ₁ - diameter of the maximum grain aggregate of the asphalt mix, cm;

d ₂ - the diameter of the maximum grain aggregate cement concrete mixture, cm;

a is the size of the base of the anchoring element of the pavement, cm, at at = 2.15d ₁ and α = 60 °;

c - the size of the truncated part of the base of the anchoring element of the pavement, cm;

C is the distance between adjacent anchoring elements in the transverse and longitudinal directions of the pavement, cm;

D is the diameter of the circle, the same area of the fingerprint of the car’s wheels as part of the road traffic provided by the project, cm

V _З - specific volume of anchoring of asphalt concrete pavement in cement concrete base, cm ³ / m ² ;

N - specific volume of the intergranular voids in the mixture of cement concrete pavement base, cm ³ / m ² _h for M ≥0,5, where M _s - surface of the module cover anchoring in the ground.

Moreover, the angle of inclination of the side surface of the anchoring element to its base is 60 °.

In this case, before the installation of asphalt concrete pavement, water is distributed on the wavy surface of the cement concrete base, the amount of which is determined from the expression:

,

,

where B is the amount of water for distribution on the surface of the cement concrete base before laying the asphalt mixture, kg / m ² ;

₁ Q - amount of heat contained in the layer of asphalt concrete mix prior to its laying on the layer of cement concrete mixture, kJ / kg;

while Q ₁ = m ₁ c ₁ (t ₁ -t ₂ ),

where m ₁ is the mass of the layer of asphalt concrete mixture of a given coating thickness, taking into account its anchoring in the base, kg / m ² ;

c ₁ - specific heat of the asphalt mix, kJ / kg ° C;

t ₁ - temperature of the asphalt mix before laying, ° C;

t ₂ is the ambient temperature, ° C;

Q ₂ - the amount of heat contained in the cement-concrete mixture layer, kJ / kg;

wherein Q ₂ = m ₂ c ₂ t ₃ , where m ₂ is the mass of the cement-concrete mixture layer of a given base thickness, kg / m ² ;

c ₂ - specific heat of the cement-concrete mixture, kJ / kg ° C;

t ₃ - temperature of the cement-concrete mixture, ° C;

L is the specific heat of water vaporization, kJ / kg.

Moreover, the device layer of asphalt concrete coating on the moistened surface of the cement concrete base is produced until the cement sets.

The combination of the above characteristics, which are significant, allows us to solve the problem.

The proposed method of construction of pavement in special cases can be additionally characterized by the following features.

As a cement-concrete mixture at the base of the pavement, a slowly hardening mineral mixture is used with the ability to gain strength in the process of compaction, for example, belite sludge.

Creation of a wavy profile in the base layer from the cement concrete mixture is carried out by pressing and removing rigid devices (dies) in the form of inverted truncated round straight cones or regular pyramids located, for example, on a cam roller drum.

In FIG. 1 shows a cross-section of pavement and a plan for placing anchoring elements on the surface of a cement concrete base, FIG. 2 is a transverse section along the axis of the anchoring element of pavement and a section plan of the anchoring element at the level of its truncated part:

1 - asphalt concrete pavement;

2 - cement concrete base;

3 - diffusion composite layer;

4 - the underlying layer of the base;

5 - a car wheel;

a is the size of the base of the anchoring element of the pavement, cm, at at = 2.15d ₁ and α = 60 °;

c - the size of the truncated part of the base of the anchoring element of the pavement, cm;

C is the distance between adjacent anchoring elements in the transverse and longitudinal directions of the pavement, cm;

D is the diameter of the circle, the same area of the fingerprint of the car’s wheels as part of the road traffic provided by the project, cm;

h _p - the thickness of the asphalt coating, cm;

h ₀ is the thickness of the cement concrete base, cm;

h _h - the depth of the anchoring of the layer of asphalt concrete pavement in the cement concrete base, see

A distinctive feature of the proposed method of erecting pavement of increased durability is an increase in the potential energy of the base as a result of the dislocation formation of cells (anchoring elements) in the unhardened cement-concrete mixture of the base in the volume of its voidness and subsequent filling of the cells with asphalt-concrete mixture in the process of coating, as well as due to the volumetric connection mutual anchoring of the coating and the base by creating additional adhesive organics on the contact layers omineralnoy composite interlayer diffusion of hydrothermal synthesis, and simultaneous redistribution of the kinetic energy of the wheel load by its concentration in the locations of the elements anchoring the pavement.

The creation of a wavy surface of the base of the cellular structure by pressing it, namely, into the unhardened cement-concrete mixture and extracting pressing devices (dies) from it, is due to the ability of the mixture in this state to exhibit plastic and isotropic properties and, when exposed to the load, due to the dislocation filling of the intergranular voids with the mixture, to ensure an increase in the density of the mixture without reducing the mass of the mixture and the destruction of the base layer, and, consequently, an increase in the places of indentation - the places of formation of the bearing elect cops anchoring, the potential energy of the structural relationships and, ultimately, improve the bearing capacity of the pavement.

In this case, the increase in the potential energy of pavement is also achieved by increasing its mass as a result of filling the cells formed by pressing and removing the dies with an additional volume of asphalt concrete mixture during the coating device.

The use of pressing devices in the form of truncated round straight cones or truncated regular pyramids is caused by the possibility of forming, by pressing them into the cement concrete mixture and extracting, discretely located in the surface layer of the base of the cells, the sizes of which are taken into account the maximum aggregate diameter of the asphalt concrete mixture (conditions 1 and 2 ), provide, when filling the cells with the mixture, the coating is anchored at the base of the pavement, due to the formation of a spatial lattice with the largest Lee homogeneous distribution of the structural and dense packing of the grains (IA Rybev Building Materials based binders (artificial construction conglomerates)): Proc. Manual for universities. - M.: Higher School, 1978 (p. 61-62).

The diameter of the truncated part of the base of the cone with a value of = 2.15d _{1 is} taken from the calculation of the most dense packing of the 3 largest grains of aggregate of the asphalt concrete mixture, which ensures, due to their mutual wedging, the increased stability of the base of the anchoring element of the pavement. In this case, the angle of inclination of the lateral surface of the rigid device (anchoring element) to its base of 60 ° creates conditions under which the size of the base, as the depth of anchoring (h _h ) changes by a multiple of 0.9d ₁ , accordingly changes by a multiple of diameter size (1.0d ₁ ).

Thus, the anchoring element of pavement with a side surface made at an angle of 60 ° to its base allows taking into account the revealed proportions, regardless of the value of d _b , not only the given shape of the element, but also its dimensions, at which the maximum packing of aggregate grains is achieved at compaction of asphalt mix.

The accepted ratio of the dimensions of the minimum diameter of the fingerprint of the car wheel to the parameters of the bearing elements for anchoring the pavement (condition 3) ensures the reduction of stresses arising from the impact of the automobile load due to the decomposition of kinetic energy by placing at least 3 load-bearing elements in the area of the fingerprint at M _h ≥0.5 (where M _s is the module of the surface for anchoring the coating at the base), which contributes to an increase in operational stability and durability of pavement.

The smallest value of the depth of the volume anchoring of the asphalt concrete mixture is taken to be the minimum thickness of the compacted layer of the asphalt concrete coating (at least 2 diameters of the largest aggregate grain), taking into account a decrease in the thickness of the anchoring layer by 0.5d _1, which ensures its combination with the coating layer, i.e. h _s = 1.87d ₁ -0.5d ₁ = 1.37d ₁ (SP 34.13330.2012. Code of practice. Roads. Updated version of SNiP 2.05.02-85, paragraph 8.33). The value of the greatest depth of anchoring of the coating layer is taken on the basis of the obvious feasibility of the maximum dislocation formation of the structure of the cement concrete base, provided that its minimum thickness at the locations of the anchoring elements of the pavement is 1.87 d ₂ under condition 4.

An increase in the durability of pavement is achieved by implementing expression (5), obtained from the condition of thermodynamic equilibrium of the specific heat content of the paved layers of the pavement and the specific heat of vaporization of water, in which the amount of water to moisten the surface of the base from the cement-concrete mixture when laying on it hot asphalt mix in pairs (Balva, O.P. Physics. - M.: EKSMO, 2014, pp. 96-97). As a result, at the contact of the layers of asphalt concrete and cement concrete mixtures, hydrothermal conditions are created that provide:

- accelerated hardening of the cement-concrete mixture due to its peak regime of high-temperature heat and moisture treatment, which allows to minimize the interruption of traffic on the road section under construction and, accordingly, reduce the costs associated with the need for long-term maintenance of concrete hardening (Bazhenov P.I., Suvorova G.F. Processing of building materials with high pressure steam. - L-d .: Gosstroyizdat, 1961, p. 53, table 22);

- the formation at the contact of the coating layers and the base of dispersed bitumen and products of hydrosilicate cementitious neoplasms capable of synthesizing organomineral compounds, which, as a result of diffusion into the layers of cement-concrete and asphalt-concrete mixtures, form an additional diffusion composite layer at the contact of the layers, which increases the bearing capacity of pavement due to bulk gluing layers to resist operational loads (RU 2441961 C2. Bahrakh GS Method of cold regeneration layers of asphalt pavement. 10.02.2012).

The use of belitic sludge as a material for foundation construction is due to the combination of technical and economic advantages of sludge compared to conventional cement concrete: the absence of setting time during the construction period, the ability to acquire strength in excess of 1.0 MPa during compaction, and the ability to self-harden during operation of the base, significantly low cost, etc. (Belousov B.V., Vysotsky Yu.N. To solving the problems of off-road. Highways. 2013, No. 9, pp. 79-80).

The practical implementation of the method of construction of pavement with anchoring layers of asphalt concrete pavement and cement concrete base is as follows.

1. The device of the base layer of cement concrete mixture is produced according to the known technology, which provides for sequential operations to prepare the mixture, transport it to the place of laying on the prepared in advance base layer of the pavement foundation or subgrade, distributing the mixture to a given thickness and its compaction (Methodological recommendations for the device of the bases of pavements of "lean" concrete). - M., Rosavtodor, 2003, from 11-17, paragraphs. 6.1 - 6.2.13).

2. The creation of a wavy surface of the cellular structure of the base by pressing into unhardened cement-concrete mixture and removing from it pressing devices (dies) in the form of truncated round straight cones or regular truncated pyramids discretely (apart), for example, located on a cam roller drum, is carried out in accordance with with the calculated parameters established in the proposed method.

An example of determining the technological parameters of the implementation of the proposed method using pressing devices in the form of truncated cones.

To establish the parameters, conditions 1-5 are used using the list of source data given in the table.

The establishment of the parameters is carried out by the calculation-experimental method by sequentially performing the following operations.

2.1. In accordance with conditions 1 and 2, the maximum values of the calculated parameters “h _s ” and “a” are determined:

h _s = h _o -1.87 d ₂ = 22-3.7 = 18.3 cm;

a = b + 2h _s ctgα = 2.15 + 2 × 18.3 × 0.58 = 23.3 cm

The obtained value of the parameter “a” requires adjustment, because does not meet conditions 3 and 4. Thus, the calculated value of the parameter “c”, characterizing the discreteness of the cellular structure of the base surface, determined from condition 3 at a = 23.3 cm, turns out to be negative, i.e. loses its physical meaning (30-46.3 = -16.3 cm).

As the calculations show, the specific volume of anchoring of asphalt concrete pavement in a cement concrete base at a = 23.3 cm is 20.8% / m ^{2 of the} base, which is more than 3 times higher than the voidness of the cement concrete mix (6.3%), determined in accordance with Instructions for the installation of cement concrete pavements for roads. BCH 139-68. Publishing House "Transport", 1968, p. 73, i.e. also does not comply with condition 4, according to which the volume of anchoring should not exceed the voidness of the cement concrete mixture.

2.2. The obtained value of parameter “a” is adjusted by iteration (selection) - a phased decrease in the maximum value of the anchoring depth (h _h ) with the corresponding calculation of the value of parameter “a” until its optimal value is established, at which conditions 3 and 4 are satisfied.

The correction of the obtained data allowed us to establish the following values of the calculated parameters for the implementation of the proposed method:

- depth of anchoring of the asphalt mix (h _h ) - the same height of the pressing device (stamp), cm, - 6.5;

- the size of the base (diameter of the cone) of the anchoring element of the pavement (a) - the same size of the base of the pressing device (stamp), cm, - 9.6;

- the distance between adjacent anchoring elements in the transverse and longitudinal directions of the pavement (s) - the same distance between adjacent pressing devices (dies), cm, - 10.8;

- the size of the truncated part of the base of the pressing device and the anchoring element of the pavement, cm, - 2.15;

- the angle of inclination of the side surface of the anchoring element to its base (α), deg, - 60.

2.3. The cellular surface of the cement concrete foundation is formed by pressing the dies using a cam roller, the parameters of the pressing devices (cams - dies) and their location on the drum of the roller are made in accordance with the original (c, α) and corrected (h _z , a, c) calculated values given in the table and clause 2.2.

Before the application of the results of the indentation test set working pressure roller, wherein, by stepwise changing the weight of the roller by a corresponding change in the ballast mass, if necessary provide the calculated depth of indentation punches (h _h) without deforming the surface of the base in the form of a mixture of cement concrete uplift.

Creating a cellular surface of the base is carried out in one pass of the roller along one track by successive reciprocating movement of the roller from one edge of the base to the other. Moreover, each subsequent pass of the roller is made without overlapping the previous pass at such a distance that the size between adjacent elements of anchoring (s) is 10.8 cm

3. Humidification of the wavy surface of the base of the cellular structure is performed by distributing the estimated amount of water using known equipment used, for example, for fine irrigation.

To calculate the amount of water (B) use the expression 5:

,

,

Where

- Q ₁ = m ₁ s ₁ (t ₁ -t ₂ ) is the amount of heat contained in the asphalt mix before laying it on the cement concrete base, kJ / kg · ° C / m ² ;

- Q ₂ = m ₂ c ₂ t ₃ - the amount of heat in the layer of cement concrete base, kJ / kg · ° C / m ² ;

- L is the specific heat of water vaporization, kJ / kg.

Substituting the values of the indicators in the formula, we get:

- Q ₁ = 90 kg / m ² × K × 1.03 kJ / kg · ° C × (160-25) ° C = 13766.0 kJ / m ² ,

where K is a coefficient taking into account the increase in the mass of the asphalt concrete mixture in the volume of anchoring (1.10);

- Q ₂ = 440 kg / m ² × 1,1 kJ / kg · ° C × 25 ° C = 12100,0 kJ / m ^2.

.Then

.

4. The device of asphalt concrete pavement is produced according to the known technology, which provides for the preparation and laying of asphalt concrete mix (SNiP 3.06.03-85 “Roads.” - M .: GUP TsPP, 2003, p. 57-65).

Using the proposed method for the construction of pavement with anchoring layers of asphalt concrete pavement and cement concrete base allows to increase the durability of pavement by increasing its potential energy, the energy of the structural bonds of cement concrete and composite volumetric combination of layers, as well as reduce stresses arising in pavement from the effects of a moving load, by directed decomposition of kinetic energy.

Claims (3)

1. A method of erecting pavement with anchoring layers of asphalt concrete pavement and cement concrete base, including arranging a base layer of cement concrete mixture, creating on its surface after hardening the mixture by milling, a wavy profile from longitudinal recesses of width and depth equal to the diameter of the maximum grain size of the aggregate of asphalt concrete mixture and its half, and the subsequent device of the coating layer of the asphalt mixture, characterized in that the creation of a wavy profile lnyayut cellular structure in the unsolidified cement concrete mixture by pressing the bed, and extraction therefrom rigid discretely spaced pinch devices (dies) in the form of inverted truncated straight circular cones or pyramids correct, the process parameters are set under the following conditions:

;

;

;

,
where h _z - the height of the pressing device (stamp) - the depth of the anchoring of the asphalt mixture, cm;
h ₀ - the thickness of the base layer of cement concrete mixture, cm;
d ₁ - diameter of the maximum grain aggregate of the asphalt mix, cm;
d ₂ - the diameter of the maximum grain aggregate cement concrete mixture, cm;
a is the size of the base of the anchoring element of the pavement, cm, at b = 2.15d ₁ and α = 60 °;
c - the size of the truncated part of the base of the anchoring element of the pavement, cm;
C is the distance between adjacent anchoring elements in the transverse and longitudinal directions of the pavement, cm;
D is the diameter of the circle, the same area of the fingerprint of the car’s wheels as part of the road traffic provided by the project, cm;
V _s - specific volume of anchoring of asphalt concrete pavement in cement concrete base, cm ³ / m ² ;
P is the specific volume of intergranular voids in the cement-concrete mixture of the base of the pavement, cm ³ / m ² , at M _s ≥0.5, where M _s is the module of the surface for anchoring the coating at the base, and the angle of inclination of the side surface of the element for anchoring to its base is 60 °
in this case, before the device of the asphalt concrete coating, water is distributed on the wavy surface of the cement concrete base, the amount of which is determined from the expression:

,
where B is the amount of water for distribution on the surface of the cement concrete base before laying the asphalt mixture, kg / m ² ;
Q ₁ - the amount of heat contained in the layer of asphalt concrete mixture before laying it on a layer of cement concrete mixture, kJ / kg;
while Q ₁ = m ₁ c ₁ (t ₁ -t ₂ ),
where m ₁ is the mass of the layer of asphalt concrete mixture of a given coating thickness, taking into account its anchoring in the base, kg / m ² ;
with ₁ - specific heat of the asphalt mixture, kJ / kg ° C;
t ₁ - temperature of the asphalt mixture before laying, ° C;
t ₂ - ambient temperature, ° C;
Q ₂ - the amount of heat contained in the layer of cement concrete mixture, kJ / kg,
wherein Q ₂ = m ₂ c ₂ t ₃ ,
where m ₂ is the mass of the cement-concrete mixture layer of a given base thickness, kg / m ² ;
with ₂ - specific heat of the concrete mixture, kJ / kg ° C;
t ₃ - temperature of the cement-concrete mixture, ° C;
L is the specific heat of vaporization of water, kJ / kg,
moreover, the device of the layer of asphalt concrete coating on the moistened surface of the cement concrete base is produced until the cement sets. 2. The method of construction of pavement according to claim 1, characterized in that as the cement-concrete mixture at the base of the pavement, a mineral slowly hardening mixture is used with the ability to gain strength in the process of compaction, for example, white mud. 3. The method of construction of pavement according to paragraphs. 1, 2, characterized in that the creation of a wavy profile of the cellular structure in an unhardened cement-concrete mixture of the base is performed by pressing and removing rigid devices (dies) located, for example, on a drum of a cam roller.

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