Ultra-high performance cement-based thin overlay anti-crack structure

Abstract

The utility model discloses an ultra-high-performance cement-based thin overlay anti-crack structure which comprises a thin overlay additionally laid on an old cement concrete pavement, and the thin overlay is made of ultra-high-performance concrete. The crack isolating layer is paved on the pavement crack in advance and is positioned below the thin overlay; uHPC (Ultra-High Performance Concrete) and crack isolation are adopted as an anti-crack structure of a thin overlay, and the pavement slotting (slotting along the full length or local part of the crack) or / and the crack isolation layer are / is adopted to adapt to the shrinkage and expansion of the concrete, so that the expansion of the reflection crack is prevented, and the anti-crack performance of the thin overlay is improved. And meanwhile, pavement slotting is beneficial to avoiding buckling instability damage of the UHPC thin overlay and bonding failure of an interlayer interface caused by expansion of adjacent plates at the cracking part of the old pavement. By means of the structure, the thin overlay has good stability, crack resistance and durability, and the problems of buckling and disengaging of the thin overlay and early fracture, fatigue failure and the like under the heavy load effect can be effectively solved.

Description

Technical Field

[0001] The utility model relates to a road surface, in particular to an ultra-high performance cement-based thin layer surface anti-cracking structure. Background Art

[0002] After years of operation, cement concrete pavements have suffered from functional defects such as surface wear, polishing, and poor flatness, as well as structural defects and damage such as potholes, misalignment, severe broken boards, and even broken boards before the design service life due to a combination of reasons such as large accumulated traffic volume, heavy loads, and possible problems in design and construction, which seriously affect the service level and driving safety of highways. It is an important and urgent issue currently facing cement concrete pavements to repair or preventively maintain the damaged pavement, restore and improve the pavement structure function and surface service function, ensure the safety and quality of use, and extend the service life of the pavement.

[0003] At present, asphalt-based materials (such as NovaChip, high-toughness ultra-thin wear layer, etc.) are almost always used for thin-layer overlays of old cement concrete pavements at home and abroad. Although they have the advantages of fast construction and good comfort, their construction requires the use of large-scale mixing plants and paving, rolling and other equipment, and some technologies have high construction requirements and are difficult to guarantee quality. At the same time, the asphalt-based overlay layer itself has deficiencies in mechanical properties, especially crack resistance, such as poor anti-reflective cracking ability, weakened bearing capacity (additional paving after milling the old concrete layer), and poor matching with the old cement concrete, which makes it difficult to guarantee the structural performance and durability of the overlay layer. Therefore, it is of great practical significance and practical value to study the anti-cracking structure of cement-based thin-layer overlays that have both functional restoration (wear resistance, anti-skid, flatness) and structural restoration and improvement (anti-heavy load, anti-reflective cracks, good durability).

[0004] When cement-based materials are used as the overlay of old cement concrete pavements, in order to meet the traffic pressure of the extra-heavy traffic grade pavement, the existing specifications stipulate that the thickness of the plain concrete overlay layer is generally not less than 20cm, and the thickness of the ordinary steel fiber concrete overlay is generally controlled at about 12cm. These two schemes not only have high engineering costs, but more importantly, they are not applicable when the old pavement overlay project has strict control requirements on the pavement elevation. If the thickness is reduced to achieve a thin layer overlay, its mechanical properties cannot meet the crack resistance and durability requirements required for structural stress, making it unfeasible. When other modified cement concrete or cement-based materials are used, such as polymer modified concrete, although its material properties are significantly improved compared to ordinary concrete, it is used for thin layers of overlay on old cement concrete pavements, especially when the old pavement has cracks and other diseases, it cannot meet the crack resistance, durability and service quality requirements required for overlay repair.

[0005] In summary, based on the shortcomings or defects of the existing asphalt-based overlay technology and cement-based overlay technology, they are not suitable for thin-layer overlay repair on old cement concrete pavements. Therefore, for the thin-layer overlay repair on old cement concrete pavements (especially when there are cracks and other diseases), effectively solving the problems of crack resistance and durability has been a key technical problem that has not been overcome for a long time. Utility Model Content

[0006] In view of this, the purpose of the utility model is to overcome the defects in the prior art and provide an ultra-high performance cement-based thin layer cover anti-cracking structure to solve the technical problems of easy cracking, breakage, interlayer detachment and poor durability of cement-based material thin layer covers.

[0007] The ultra-high performance cement-based thin-layer overlay anti-cracking structure of the utility model comprises a thin-layer overlay paved on an old cement concrete pavement, wherein the thin-layer overlay is ultra-high performance concrete;

[0008] Furthermore, it also includes a crack isolation layer pre-laid on the cracks of the road surface, wherein the crack isolation layer is located under the thin layer cover;

[0009] Furthermore, the crack isolation layer is laid with a width of 3 to 6 cm, and the thickness of the thin layer cover is 2 to 4 cm;

[0010] Furthermore, the crack isolation layer is laid at intervals or continuously along the length direction of the crack;

[0011] Further, when the old road panel has transverse cracks, the crack isolation layer is laid corresponding to the cracks at the edge of the cement concrete panel or / and below the wheel track; when the old road panel has longitudinal cracks and there are cracks at the edge of the panel or below the wheel track, the crack isolation layer is laid corresponding to the cracks at the edge or below the wheel track; when the old road panel has longitudinal cracks and there are no cracks at the edge of the panel or below the wheel track, the crack isolation layer is laid / not laid;

[0012] Furthermore, the crack isolation layer is arranged in a groove opened on the surface of the old cement concrete slab along the crack;

[0013] Furthermore, a groove is provided along the entire length of the crack direction of the old road slab, with a width of 2 to 4 cm and a depth of 3 to 6 cm;

[0014] Furthermore, the interface bottom and side surfaces of the groove are paved with a crack isolation layer or isolation material;

[0015] Furthermore, the groove is filled with ultra-high performance concrete to form a filling layer flush with the panel, and an isolation layer is laid on the filling layer, and the width of the isolation layer is 2 to 4 cm wider than the slot opening;

[0016] Furthermore, grooves are partially opened along the crack direction of the old road panel, with a groove width of 2 to 4 cm and a depth of 3 to 6 cm, and the grooves are located at symmetrical positions at both ends and the middle of the crack length;

[0017] Furthermore, the groove cross-section is rectangular, trapezoidal, U-shaped, approximately U-shaped, circular, cylindrical or any of the above approximate shapes, and the crack isolation layer is a plastic film or other materials that can prevent cement slurry from penetrating.

[0018] Beneficial effects of the utility model: The ultra-high performance cement-based thin-layer overlay anti-cracking structure of the utility model adopts UHPC (ultra-high performance concrete) and crack isolation as the anti-cracking structure of the thin-layer overlay, and adopts road surface grooving (grooving along the entire length of the crack or partially) or / and crack isolation layer to adapt to the contraction and expansion of concrete, and prevent the expansion of reflective cracks. At the same time, road surface grooving is beneficial to avoid the UHPC thin-layer overlay buckling and instability damage caused by the expansion of adjacent slabs at the crack of the old road surface and the failure of interlayer interface bonding. The above structure makes the thin-layer overlay have good stability, crack resistance and durability, and can effectively solve the problems of buckling, de-airing, early fracture and fatigue damage of the thin-layer overlay under heavy load. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The utility model is further described below in conjunction with the accompanying drawings and embodiments:

[0020] Figure 1 This is a schematic diagram of the structure in which the isolation layer is laid on the crack at intervals;

[0021] Figure 2 It is a schematic diagram of a thin layer cover structure having a rectangular or U-shaped groove structure;

[0022] Figure 3 It is a schematic diagram of a thin layer cover structure having a trapezoidal or approximately U-shaped groove structure;

[0023] Figure 4 It is a schematic diagram of the structure in which the isolation layer is laid in a local cylindrical groove. DETAILED DESCRIPTION

[0024] Figure 1 This is a schematic diagram of the structure in which the isolation layer is laid on the crack at intervals; Figure 2 It is a schematic diagram of a thin layer cover structure having a rectangular or U-shaped groove structure; Figure 3 It is a schematic diagram of a thin layer cover structure having a trapezoidal or approximately U-shaped groove structure; Figure 4 This is a schematic diagram of the structure where the isolation layer is laid in a local cylindrical groove. As shown in the figure:

[0025] The ultra-high performance cement-based thin-layer overlay crack-resistant structure of the utility model comprises a thin-layer overlay 2 added on the old cement concrete pavement, wherein the thin-layer overlay 2 is ultra-high performance concrete; the thin-layer overlay 2 is directly laid on the old cement concrete pavement, which is suitable for the case where the old road panel has no cracks, and can also be used for the case where the old panel has cracks. When the old panel has no cracks, there is no need to set an isolation layer; when the old panel has cracks, there is no need for an isolation layer, and the excellent crack resistance of the UHPC overlay material itself is relied on to resist reflective cracks and vehicle fatigue.

[0026] Another solution of this embodiment is to pre-lay an isolation layer 1 on the cracks of the pavement, and then lay a thin layer of cover 2 to cover the entire old cement concrete pavement after the isolation layer 1 is constructed; first lay a crack isolation layer 1 along the cracks 5 of the old cement concrete pavement 4 to cover the cracks 5, and then lay a UHPC thin layer of cover 2, and the formed thin layer of cover 2 has good crack resistance and fatigue durability. The so-called crack isolation layer 1 is to isolate the thin layer of cover 2 from the cracks 5 to prevent the thin layer of cover 2 from directly bonding with the old pavement at the cracks. Therefore, the shrinkage and deformation of the old road panel under temperature changes in the cracks 5 will not cause the thin layer of cover 2 on the cracks 5 to crack due to excessive local tensile stress or tensile strain. It can also effectively solve the problem of reflective cracks caused by tensile stress concentration at the bottom of the cover layer 2 under vehicle load, greatly improve the heavy-load crack resistance and fatigue life of the ultra-thin UHPC cover, and achieve the goal of long-life cover design and use. Because if the isolation layer 1 is not provided, reflective cracks will appear at the bottom of the overlay layer due to the shrinkage and deformation of the old road panel and the action of vehicle loads, and with the repeated action of vehicle loads, the cracks will expand upwards, and may form macroscopic reflective cracks visible on the road surface, that is, the plate breaking phenomenon will occur. In addition, if ultra-high performance concrete is directly laid on the thin overlay 2 of the old cement road surface, since the thickness of the thin overlay 2 is very small and thin (preferably the thickness of the thin overlay is 2 to 4 cm), when the temperature expands, the cement concrete on both sides of the crack 5 squeezes inward along the crack 5. If the thin overlay 2 is bonded to the crack 5, then the thin overlay 2 on the crack 5 will buckle and become unstable under extrusion, which directly leads to the cracking of the thin overlay 2 and the failure of its interface bonding with the old concrete road surface, further affecting the crack resistance, durability and service quality of the overlay layer. After the isolation layer 1 is set, the thin layer cover 2 on the crack 5 can be prevented from being affected by the extrusion of cement concrete. The thin layer cover 2 is not bonded to the old road surface at the crack 5. The deformation of the crack 5 will not produce tensile stress on the thin layer cover 2, and will not affect the thin layer cover 2.

[0027] The scheme of laying an isolation layer on cracks is suitable for old road panels with through cracks, and the crack width is small, and the width of the isolation layer is 3 to 6 cm. Compared with the scheme without laying an isolation layer, this scheme of laying an isolation layer is more conducive to resisting the cracking and crack propagation of the ultra-thin cover layer 2 caused by temperature changes and heavy-loaded vehicles and vehicle load fatigue. The cracking load is significantly increased and the crack propagation rate is greatly reduced.

[0028] In the present embodiment, the crack isolation layer 1 is laid at intervals or continuously along the length direction of the crack; for example, the crack isolation layer 1 is arranged at intervals on a transverse crack 5 instead of full isolation. This not only ensures that the thin layer cover 2 and the old road panel are effectively bonded in the local area where the isolation layer is not set, but also the slurry during the construction of the UHPC cover can penetrate into the cracks (cracks with a width of more than 2 to 3 mm), filling and closing the cracks while preventing the old panels on both sides from squeezing inward and causing the thin layer cover 2 to buckle and the interlayer interface to lose adhesion and de-airing. In the local area where the crack isolation layer 1 is set, the problem of cracking of the cover layer caused by shrinkage and stress concentration under vehicle load can be effectively solved, thereby enhancing the deformation resistance and crack resistance of the thin layer cover 2.

[0029] In this embodiment, when the old road panel has transverse cracks, the crack isolation layer 1 is laid corresponding to the cracks at the edge of the cement concrete panel 4 and / or below the wheel track belt; when the old road panel has longitudinal cracks and there are cracks at the edge of the panel or below the wheel track belt, the crack isolation layer is laid corresponding to the cracks at the edge or below the wheel track belt; when the old road panel 4 has longitudinal cracks and there are no cracks at the edge of the panel or below the wheel track belt, it is optional to lay or not lay the crack isolation layer 1.

[0030] In this embodiment, the entire length or part of the groove is made along the crack direction of the old road panel, with a groove width of 2 to 4 cm and a depth of 3 to 6 cm. The bottom and sides of the groove interface (the sides can be laid without paving, which is not necessary, but can also be laid) are paved with an isolation layer or coated with isolation materials such as engine oil, so that the UHPC covering material filled later does not adhere to the bottom. After the groove is opened and filled with UHPC covering material, the filling layer is smoothed, and then an isolation layer is laid on it. The width of the isolation layer is 2 to 4 cm wider than the groove opening, and finally a thin layer of UHPC covering is paved on the isolation layer;

[0031] If the grooves are localized, the grooves are located at the two ends and the middle symmetrical positions along the length of the cracks. This solution is suitable for the cracks of the old road panels are relatively wide, generally 0.1 to 2 mm, and the UHPC mixture slurry cannot penetrate and partially fill the cracks due to its fluidity. If the grooves are not artificially opened and filled, the UHPC thin layer of the cover will be squeezed and buckled and unstable when the cover structure is heated and expanded and deformed in the later stage, and the interlayer interface bonding fails, degassing and other damages will occur.

[0032] The groove cross-section is one of rectangular, trapezoidal, U-shaped, approximately U-shaped, circular, cylindrical and the above approximate shapes. The crack isolation layer is a film or other material that can prevent cement slurry from penetrating. When the slot structure is circular, it also includes a local slot drilled by a cylindrical drilling machine. In construction, rectangular, trapezoidal or approximately rectangular slot structures are generally used. Figure 3 As shown, the groove is a trapezoidal structure, which refers to the cross-sectional structure from the groove mouth to the groove bottom.

[0033] It should be noted that when circular holes are used for local grooving, drilling is adopted with a diameter of 3 to 8 cm. On the one hand, the construction is more convenient. On the other hand, the circle has complete axial symmetry and there are no right angles left by the cutting of rectangular grooves. This can avoid cracking caused by stress concentration at the right angles, which is more beneficial in terms of the stress of the old board itself and the stress of the cover layer.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model rather than to limit it. Although the utility model has been described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. An ultra-high performance cement-based thin layer overlay anti-cracking structure, characterized by: It includes a thin layer of overlay paved on an old cement concrete pavement, wherein the thin layer of overlay is ultra-high performance concrete.

2. The ultra-high performance cement-based thin layer overlay anti-cracking structure according to claim 1 is characterized in that: It also includes a crack isolation layer pre-laid on the cracks of the road surface, and the crack isolation layer is located under the thin layer cover.

3. The ultra-high performance cement-based thin layer overlay anti-cracking structure according to claim 2 is characterized by: The crack isolation layer is laid with a width of 3-6 cm; the thickness of the thin layer cover is 2-4 cm; the crack isolation layer is laid at intervals or continuously along the length direction of the crack.

4. The ultra-high performance cement-based thin layer overlay anti-cracking structure according to claim 3 is characterized by: When the old road panel has transverse cracks, the crack isolation layer is laid corresponding to the cracks at the edge of the cement concrete panel and / or below the wheel track; when the old road panel has longitudinal cracks and there are cracks at the edge of the panel or below the wheel track, the crack isolation layer is laid corresponding to the cracks at the edge or below the wheel track; when the old road panel has longitudinal cracks and there are no cracks at the edge of the panel or below the wheel track, the crack isolation layer is laid / not laid.

5. The ultra-high performance cement-based thin layer overlay anti-cracking structure according to claim 2 is characterized in that: The crack isolation layer is arranged in a groove opened on the surface of the old cement concrete slab along the crack.

6. The ultra-high performance cement-based thin layer overlay anti-cracking structure according to claim 5 is characterized by: A groove is opened along the entire length of the crack direction of the old road panel, with a width of 2-4 cm and a depth of 3-6 cm.

7. The ultra-high performance cement-based thin layer overlay anti-cracking structure according to claim 6 is characterized by: The interface bottom and side surfaces of the groove are paved with a crack isolation layer or isolation material.

8. The ultra-high performance cement-based thin layer overlay anti-cracking structure according to claim 6 is characterized by: The groove is filled with ultra-high performance concrete to form a filling layer flush with the panel, and an isolation layer is laid on the filling layer. The width of the isolation layer is 2-4 cm wider than the groove opening.

9. The ultra-high performance cement-based thin layer overlay anti-cracking structure according to claim 5, characterized in that: Grooves are partially opened along the crack direction of the old road panel, with a width of 2-4 cm and a depth of 3-6 cm. The grooves are located at symmetrical positions at both ends and the middle along the length of the crack.

10. The ultra-high performance cement-based thin layer overlay anti-cracking structure according to any one of claims 5 to 9, characterized in that: The cross section of the groove is one of a rectangle, a trapezoid, a U shape and a circle, and the crack isolation layer is a plastic film or other materials that can prevent cement slurry from penetrating.

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