RU2847771C1 - Method for forming the carriageway of a bridge structure with a reinforced deck structure - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: invention relates to the field of bridge construction, namely to methods of forming road surfaces on bridge structures. To improve working conditions and strengthen the road surface of the carriageway and prevent the formation of cracks, it is proposed to install a damper membrane directly on the waterproofing with a geogrid glued to it, both in the lower part of the asphalt concrete pavement and between its structural layers. Temperature effects and the corresponding tensile stresses, as well as tensile stresses near the walls of the main beams from the design loads of motor vehicles, are most pronounced closer to the surface of the pavement. To reduce these stresses, a damper membrane with a bonded geogrid is placed as close to the surface as possible in the asphalt concrete, which significantly reduces the stresses in the upper part of the asphalt concrete pavement. Geogrids, together with damper membranes, are capable of absorbing significantly greater tensile loads. Due to their increased modulus of elasticity compared to asphalt concrete, they work together with the road surface, increasing the overall stiffness of the system and thereby reducing the level of stress throughout the asphalt concrete pavement. Geogrids, together with damper membranes, also lead to a more uniform distribution of stress fields across the lower and upper parts of the pavement, reducing the external force exerted by vehicles, which is dissipated over the load cycle, helping to reduce the possibility of cracking, reduce rutting and increase the fatigue life of the asphalt concrete pavement. The plasticity range of the protective bonding layer and the sub-base bonding layer, as well as the composite binder used in the preparation of asphalt concrete mixtures for the construction of structural layers of asphalt concrete pavement, must be at least 120°C (KiSh above +80°C, Fraas - not higher than -40°C and/or binder grade PG 82(Z)-40 (PG 76(Z)-40) with J_nr10 less than 0.5 kPa^-1 at T_calc=+80°C).

EFFECT: reliable adhesion is achieved between the materials of the riding surface and the waterproofing over an area of at least 75% in the cells between the longitudinal and transverse threads of the geogrid.

2 cl, 7 dwg

Description

The proposed invention relates to a method for constructing (forming) a road surface on bridge structures, in particular, to a method for forming a roadway with a reinforced structure of the driving surface of a bridge structure on an orthotropic slab using a geogrid and a membrane both in the lower part of the asphalt concrete surface and between its structural layers. A method is proposed for forming a reinforced multilayer roadway structure of a road surface of a driving surface on an orthotropic slab of an individual design, which includes at least the following, sequentially arranged by height (thickness) on a covering metal sheet of the deck: waterproofing (9), a composite rubber-polymer-bitumen membrane made of RPBV 40 or RPBV 60 (8) with a geogrid (7) installed on it, a protective-adhesive layer (6), cast asphalt concrete (5), a composite rubber-polymer-bitumen membrane made of RPBV 40 or RPBV 60 (4) with a geogrid (3) installed on it, a sub-priming-adhesive layer (2), stone mastic asphalt concrete (SMA) or another type of asphalt concrete (1) (see file "drawings", Fig. 1).

Moreover, in all the above-mentioned structural layers of asphalt concrete pavement, composite rubber-polymer-bitumen membranes, as well as in the protective-adhesive and sub-primer-adhesive layers, a composite rubber-polymer-bitumen binder with a wide range of plasticity from +80°C to -42°C and/or grade PG82Z-40 (PG76Z-40) with a non-restorable creep compliance J _nr of less than 0.5 kPa ^-1 at a design temperature T _calc equal to 80°C is used as a binder. The numbers in the specified binder grades indicate their maximum and minimum permissible temperatures for the type of grade Z binder at a specific level of transport load (S, H, V, E) capable of maintaining the necessary properties that ensure the required shear resistance according to the parameter of non-restorable creep compliance J _nr [1], [2].

In this case, in order to ensure the above-mentioned wide range of plasticity of the used composite rubber-polymer-bitumen binder, which meets the requirements of the specific natural and climatic conditions of the region of construction, reconstruction and repair of certain bridge structures, it is advisable that petroleum road bitumen grade BND 100/130 and/or BND 70/100 according to GOST 33133-2014 be used as the initial bitumen.

The claimed invention is based on the task of creating a method for forming a roadway of a bridge structure on an orthotropic slab, which ensures a reduction in transverse tensile stresses between the longitudinal stiffeners of the orthotropic slab (11) in the lower part of the lower layer of asphalt concrete pavement (5) and part of the transverse tensile stresses above the main beams of the superstructure (13) in the upper part of the upper layer of asphalt concrete pavement (1) by means of the perception by geogrids (7) and (3) of part of the said tensile stresses and, accordingly, ensures a reduction in the ultimate stresses that cause unacceptable deformations in the asphalt concrete layers, due to which the fatigue life of the asphalt concrete pavement as a whole is increased (see file "drawings", Fig. 1).

The reduction of the said stresses will also be facilitated by buffer layers formed in the form of damper membranes (4) and (8) based on composite modified bitumen binders, arranged, respectively, on the surface of the waterproofing (7) and between the structural layers of the asphalt concrete pavement (see file “drawings”, Fig. 1).

The installation of a reinforcing geogrid between the structural layers of the asphalt concrete pavement and in the lower portion of the asphalt concrete pavement increases the overall rigidity of the entire road surface. In this case, in addition to increasing the overall rigidity of the road surface, it acts as a "flexible grillage" (the bottom layer of the asphalt concrete pavement, fully encased), resting, together with the metal cover sheet, on the longitudinal stiffeners of the orthotropic slab, cross beams, and main beams.

A buffer layer together with a sub-primer-bonding layer (2), formed in the same form as the damper membrane (8) based on composite modified bitumen binders, arranged on the surface of the structural layer made of cast asphalt concrete (5) (see file "drawings", Fig. 1), will contribute to the reduction of stresses, including those associated with temperature effects. This will reduce tensile stresses in the upper part of the asphalt concrete pavement above the walls of the main beams, which, in turn, will prevent the formation of cracks above the main beams (see file "drawings", Fig. 1, Fig. 3).

As already noted [1], the nature of the performance of the pavement on artificial structures differs significantly from that on highways, where the pavement (1) and (3), like the entire road surface (1), (3), (14) and (15) rests on a homogeneous and continuous medium of the subgrade (16), and its deformation characteristics (modulus of elasticity) vary significantly less throughout the entire area taken into account in the calculation (see file "drawings", Fig. 2). An orthotropic slab, however, is distinguished by a significantly more flexible base (8) compared to the subgrade and is not constant from the point of view of the rigidity of the structure (see file "drawings", Fig. 3), since the decking sheet is connected to longitudinal stiffening ribs (stringers) (9), the walls of the main (11) and transverse (10) beams, which actually act as elastically deformable supports of varying rigidity (see file “drawings”, Fig. 3, Fig. 6).

This is due to the fact that, when exposed to a transport load (12), the upper part of the asphalt concrete pavement (1) above the wall of the main beam (11) (see the file "drawings", Fig. 3) will be in the tension zone, and not the compression zone, as in the road pavement constructed on the roadbed of the highway (1) (see the file "drawings", Fig. 2). The road pavement constructed on artificial structures experiences significantly greater tensile stresses than on a highway, especially above the walls of the main beams.

According to research, cracks appear in the asphalt concrete pavements of 30% of large and medium-sized bridges after just one year of operation, and the frequency of replacing the upper structural layer of the asphalt concrete road surface often does not exceed 5 years [3]. Therefore, the issue of constructing a roadway with a reinforced road surface on orthotropic bridge slabs is becoming increasingly important, particularly if the distance between the longitudinal stiffeners on orthotropic slabs of older bridges exceeds 300 mm, and the thickness of the covering metal sheet is less than 14 mm.

The very fact that cracks (13) appear after some time indicates that the probable cause of their occurrence is the insufficient durability of asphalt concrete (1) and (3) (see the "drawings" file, Fig. 3, Fig. 4, Fig. 5) according to the fatigue failure criterion due to the road surface's exposure to repeated cyclic loads under variable natural and climatic conditions. The organic binders used play a particularly important role in withstanding the challenging natural and climatic operating conditions at specific construction, reconstruction, and repair sites of bridge structures. They must ensure the shear resistance, fatigue life, and low-temperature crack resistance of the asphalt concrete used, as required for these conditions.

It should also be taken into account that the asphalt concrete pavement, installed on an elastically deformable base in the form of an orthotropic slab, bends with significant amplitudes under the influence of a moving traffic load (12), which causes alternating stresses in the asphalt concrete pavement of the roadway. As a result, microcracks (13) form in the asphalt concrete pavement (see the "drawings" file, Fig. 3, Fig. 5, Fig. 6).

Microdamage in the form of microcracks gradually accumulates in asphalt concrete and can develop into macro-defects with a violation of the continuity (integrity) of the structural layer with the formation of deep cracks (13) (see file "drawings", Fig. 3, Fig. 4, Fig. 6), chipping of their edges and destruction of the coating, especially above the main beams, and with a small thickness of the covering sheet less than 14 mm, and above the longitudinal stiffening ribs (see file "drawings", Fig. 7).

In the part concerning the nature of deformation of asphalt concrete pavement as part of the superstructure, the appearance of longitudinal cracks in the pavement (see file "drawings", Fig. 7) occurs, as a rule, due to excessive flexibility of the orthotropic slab and especially the covering metal sheet of the orthotropic slab (10) (see file "drawings", Fig. 3, Fig. 4), designed in the 1960-1970s, the thickness of which did not exceed 12-14 mm. Due to local deformations from the moving load, transverse tensile stresses arise above the walls of the longitudinal ribs of the closed section, formed from the transverse bending of the pavement itself and the vertical displacement of one rib relative to another (see file "drawings", Fig. 4, Fig. 5, Fig. 6). The first component is more pronounced near the cross beams (10) (see file “drawings”, Fig. 4), the second - near the wall of the main beam (11) (see file “drawings”, Fig. 6), and approximately equal ratios are observed in the span of the longitudinal rib (9) (see file “drawings”, Fig. 5).

Geogrids reinforce asphalt concrete by increasing the strength of the reinforced asphalt concrete pavement as a system (asphalt concrete pavement plus geogrid) by absorbing and redistributing tensile stresses from vehicle impact and/or thermal deformations. The choice of the reinforcing layer's location within the pavement thickness depends on its primary purpose—to absorb vehicle wheel impacts corresponding to the transverse stresses in the lower portion of the asphalt concrete from the design load on the roadway, both with strip and trapezoidal ribs (stringers)—closer to the base of the asphalt concrete pavement (see the "Drawings" file, Fig. 1, Fig. 3, Fig. 4). Thermal effects and the corresponding tensile stresses, as well as tensile stresses near the main beam walls from the calculated vehicle loads, are most pronounced closer to the pavement surface. We plan to take this into account by placing the membrane with the bonded geogrid as close to the surface as possible (see the "Drawings" file, Fig. 1, Fig. 6), significantly reducing stresses in the upper portion of the asphalt concrete pavement. In any of the presented exposure cases, the asphalt concrete must operate in the elastic state without plastic deformation. This is greatly facilitated by both the installed geogrids and the damper membranes made of a composite rubber-polymer-bitumen binder, which absorb part of the work of the external force (vehicle wheels), dissipated (dissipated) during the load cycle, which is spent on the elastic recovery of the asphalt concrete pavement after its deformation.

When strengthening the structures of the driving surface of bridge structures by reinforcing the asphalt concrete structural layers of the road surface of the driving surface, it is necessary that the geogrids (3) and (7) used have a low relative elongation at break and a high tensile modulus, which allows for the almost immediate activation of the work of the geogrid material in the asphalt concrete pavement and the effective redistribution of local stresses over a sufficient volume of asphalt concrete (which is what we provide for when installing geogrids both in the lower part of the asphalt concrete pavement and between its structural layers), significantly slowing down the formation of reflected cracks caused by dynamic traffic loads and seasonal temperature fluctuations in the road surface of the driving surface [1], [3].

The primary cause of the formation of a region of significant transverse tensile stresses in the lower portion of the asphalt concrete between the longitudinal stiffeners under the action of a moving load is the higher compliance of the protective-adhesive layer compared to the pavement material. As a result, during deformation, the lower structural layer slips along the waterproofing relative to the covering sheet of the deck. To improve the performance of the road surface, it is proposed to use a geogrid such as HaTelit XP100 (polyvinyl alcohol fiber material, relative elongation no more than 6%, and a load at 3% elongation of 44 kN/m) or AGM-DOR(P) (manufactured by JSC VATI, Volzhsky, Stavropol Krai), adhering it to a rubber-polymer-bitumen membrane installed directly on the waterproofing layer. Geogrids are capable of withstanding significantly greater tensile loads, and due to their increased modulus of elasticity and tensile strength in the asphalt concrete layer, compared to asphalt concrete, they interact with the road surface, increasing the overall rigidity of the system by absorbing a significant portion of the horizontal tensile stresses and thereby reducing the stress level along the lower portion of the asphalt concrete pavement [1]. Furthermore, the geogrids installed should result in a more uniform distribution of stress fields over a larger area, both in the lower portion of the asphalt concrete pavement (its bottom layer) and between its structural layers, preventing the occurrence and propagation of reflected cracks by absorbing shear forces, which is important since asphalt concrete is a heterogeneous material.

The geogrid intended for use is impregnated with a dispersion adhesive binder during its production on weaving equipment under tension. After being rolled into a roll, it shrinks by 1-3% and acquires the properties of a prestressed reinforcing element [4]. It is also important to note that the geogrid is installed in the roadway structure within a range of 1-2% of its relative elongation to support the load, which allows it to withstand loads without play in the prestressed state. In addition to possessing the property of being free of play, the above-mentioned geogrids easily assume a flat shape or the desired shape of the reinforced surface when distributed, and can bend under tension, conforming to uneven surfaces with alternating curvature. The composite material AGM-Composite or Kevlar (Kevlar is a para-aramid fiber (polyparaphenylene terephthalamide) that is 5 times stronger than steel) has special capabilities. Its operating principles are identical to the features of shaping and repairing volumetric and load-bearing elements of an aircraft (volumetric covering, flat bending with stretching) [4]. The use of geogrids also makes it possible to effectively solve the problem of equalizing hydrostatic pressure in the road surface of bridge structures.

As already noted in [1], for the high-quality inclusion of a geogrid in joint work, it is necessary to ensure its adhesion to other contacting materials. This is achieved through the formation of chemisorption bonds - the absorption of a substance by the surface of the geogrid (chemisorbent) as a result of the formation of a chemical bond between the molecules of the chemisorbent and the materials of the asphalt concrete road surface and membrane (protective-adhesive and sub-primer-adhesive layers). In addition, the plasticity range of the material of the sub-primer layer and the protective-adhesive layer must be at least 120 ° C (KiSh above + 80 ° C, Fraas - not higher than - 40 ° C and / or binder grade PG 82 (Z) - 40 (PG 76 (Z) - 40) with J _nr10 less than 0.5 kPa ^-1 at T _calc = + 80 ° C) [2], [5], [6]. This ensures reliable adhesion between the materials of the road surface and the waterproofing over an area of at least 75% in the cells between the longitudinal and transverse threads of the geogrid.

The formation of a damper membrane (8) (see file "drawings", Fig. 1) is carried out by means of a step-by-step distribution of the composite bitumen binder using a bitumen distributor, distributing the binder at each stage in the amount of 1 l/m2 until a total thickness of 3...4 mm is achieved with subsequent distributions of the binder. As a rule, 3...4 passes of the bitumen distributor are sufficient to obtain the required thickness of the damper membrane. In this case, after the final distribution of the said binder at its temperature of 120...140°C, the geogrid is tightly glued and, together with the geogrid, it is sprinkled with hot (from 130°C to 145°C) pre-blackened crushed stone material of a fraction over 4 mm to 8 mm or over 2 mm to 4 mm with an average consumption of 3 to 5 kg/m2 and, if necessary, it is compacted with a light roller in 1...2 passes in one track. In this way, a protective-adhesive layer (6) is formed, on which the lower layer of asphalt concrete pavement made of cast asphalt concrete (5) is subsequently installed (see file “drawings”, Figs. 1, 3, 4, 5).

The damper membrane (4) is formed on the constructed structural layer of cast asphalt concrete (5) in the same way as the damper membrane (8) (see the file "drawings", Fig. 1). In this case, after the final distribution of the specified binder for forming the membrane, at its temperature of 120...140°C, the geogrid is tightly glued and, together with the geogrid, it is sprinkled with hot (from 130°C to 145°C) pre-blackened crushed stone of a narrow fraction over 4 mm to 8 mm or over 8 mm to 12 mm at a rate of 5...7 kg/m2 and, if necessary, it is compacted with a light roller in 1...2 passes in one track. In this way, a sub-primer-bonding layer (2) is formed on a constructed membrane (4) with a geogrid (3) tightly glued to it on a structural layer of cast asphalt concrete.

The structural pavement layer made of stone mastic asphalt (SMA) or another type of asphalt concrete is installed immediately after the formation of the sub-base-bonding layer (2) within the first 1...2 days (See the file "drawings", Fig. 1). In order to prevent contamination of the formed surface of the layer, no vehicles are allowed to pass over it. If it is impossible to ensure the specified conditions, the sub-base-bonding layer is installed using standard technology after cleaning the surface of the cast asphalt concrete from dust and dirt with the distribution of a composite binder in the amount of 0.7...0.9 l/ ^m2 and subsequent distribution of hot blackened crushed stone of a fraction over 8 to 12 mm using a crushed stone distributor in the amount of 5...7 kg/ ^m2 .

ANALOGUES

There are no analogues of this method of forming the roadway of a bridge structure on an orthotropic slab with a multi-layer design of the road surface structure using a geogrid and a membrane in the lower part and between the structural layers of asphalt concrete pavement.

TECHNICAL INNOVATION

In this invention application, the following solutions are applied for the first time in practice (included in the working design for the bridge reconstruction):

- technology and design of a damper membrane, installed both in the lower part of the asphalt concrete pavement and between its structural layers with a geogrid attached to it.

SCOPE OF APPLICATION

The design and method for forming the roadway of a bridge structure on an orthotropic slab with a reinforced multilayer structure of the road surface of the driving surface with the installation of a damper membrane, arranged both in the lower part of the asphalt concrete surface and between its structural layers with a geogrid secured to it, were designed during the construction of a bridge on the A-114 Vologda - Novaya Ladoga highway to the KOLA highway in the Vologda region, part of which was the bridge across the Sheksna River PK 56+23 [5].

References:

1. Patent. 2828718 (RU), Method for forming the roadway of a bridge structure [Text] / JSC for the design of bridge construction "Institute Giprostroymost"; applicant and patent holder JSC for the design of bridge construction "Institute Giprostroymost" - No. 2023132051; declared December 6, 2023; published October 16, 2024.

2. Patent 2752619 (RU), IPC C08L 95/00 (2021.05); C08J 3/20 (2021.05); C08K 9/00 (2021.05); C08K 5/00 (2021.05); C08J 11/00 (2021.05). Rubber-polymer-bitumen binder and method for producing it [Text] / Stepanov V.F., Dubina S.I.; applicant and patent holder Stepanov V.F., Dubina S.I. - No. 2020130918; declared 21.09.2020; published 29.07.2021, Bulletin No. 22.

3. S. Yu. Polyakov, "Improving the Method for Calculating the Durability of Asphalt Concrete Pavements on Orthotropic Bridge Slabs Based on the Fatigue Failure Criterion." Dissertation for the degree of Candidate of Engineering Sciences. Novosibirsk, 2022, 165 p.

4. Kochetkov A.V., Sotnikov A.V. "Application of aircraft manufacturing technologies for the calculation and installation of polymer road meshes." Article in the journal "Roads. Innovations in Construction. Special Issue", February. 2021. - Pp. 12-19.

5. S. Yu. Polyakov, A. M. Panichev, "Use of Geogrids for Reinforcing Asphalt Concrete on Orthotropic Slabs." Article in the journal "Roads. Innovations in Construction" No. 91, February 2021, pp. 46–48.

6. S.I. Dubina, "Ensuring the Reliability of Asphalt Concrete Pavements Using Composite Rubber-Polymer-Bitumen Binders." Joint Ceremonial Meeting of the Academic Council of the Federal Research Center of Chemical Physics of the Russian Academy of Sciences, the Presidium of the Russian Academy of Sciences, and the Department of Chemical Science of the Russian Academy of Sciences, Moscow, April 15-16, 2021.

Claims (3)

1. A method for forming a reinforced roadway of a bridge structure on an orthotropic slab, characterized by the following: that at least one metal mounting block is mounted from orthogonally intersecting longitudinal ribs and transverse beams, which are reinforced at one level and rigidly connected with a covering sheet of the orthotropic slab decking, on which waterproofing is performed sequentially located along the height, a buffer layer in the form of a damper membrane based on composite modified bitumen binders, which are used as rubber-polymer-bitumen binder RPBV-40 or RPBV-60 with a wide range of plasticity at a temperature of at least 130 ° C or 120 ° C, respectively, a geogrid is tightly glued to the membrane layer and sprinkled with hot crushed stone of a fraction over 4 mm to 8 mm or over 2 mm to 4 mm with an average consumption of 3 to 5 kg / m ² with the formation of a protective-adhesive layer, then an asphalt concrete pavement is formed from the lower and upper layers, while the lower finally leveling the layer is made of cast asphalt concrete, on which a buffer layer is arranged in the form of a damper membrane based on composite modified bitumen binders, which are rubber-polymer-bitumen binders RPBV-40 or RPBV-60 with a wide range of plasticity of at least 130 ° C or 120 ° C, respectively, a geogrid is tightly glued to the membrane layer, on which a sub-primer-adhesive layer is arranged from hot blackened crushed stone with a temperature from 130 ° C to 145 ° C with a fraction of over 4 mm to 8 mm, or over 8 mm to 12 mm with an average consumption of 5 to 7 kg / m ² , then the top layer of crushed stone mastic or another type of asphalt concrete. 2. The method according to paragraph 1, characterized in that the buffer layer in the form of a damper membrane with a geogrid fixed to it is arranged both in the lower part of the asphalt concrete pavement and between the structural layers of the pavement.