Interlayer binder for new and old concrete interface of airport pavement and treatment method thereof

Abstract

The invention relates to an interlayer binder for new and old concrete interfaces of airport pavements and a treatment method of the interlayer binder, the interlayer binder is cement mortar modified by a powdery polymer and comprises early strength cement, silica fume, water, the powdery polymer, basalt machine-made sand, a polycarboxylic acid superplasticizer and an organic silicon defoaming agent, and the early strength cement, the silica fume, the water, the powdery polymer, the basalt machine-made sand, the polycarboxylic acid superplasticizer and the organic silicon defoaming agent are mixed. The mass of the powdery polymer is 1.4%-2.2% of the mass of the early strength cement; the mass ratio of the solid content of the polycarboxylate superplasticizer to the cement is 0.3%-1.0%; the mass of the silica fume is 8-13% of the mass of the cement. The interlayer binder and the treatment method thereof are suitable for surface layer additional paving after functional damage of the airport cement concrete pavement, the problem that the bonding performance of new and old concrete interfaces of the airport pavement is insufficient is solved, the interlayer performance and structural toughness of the repaired airport pavement are improved, and the service life of the repaired airport pavement is prolonged.

Description

Technical Field

[0001] The invention relates to the treatment of airport pavement concrete structure, in particular to an interlayer adhesive used for the interface between new and old concrete of the airport pavement and a treatment method thereof. Background Art

[0002] Under the extremely heavy loads of aircraft takeoff and landing, turning, and braking, the surface of the airport's cement concrete pavement generates strong impact and lateral forces. At the same time, under the long-term coupling of environmental factors, it causes functional defects such as friction and particle loss, surface cracking, and texture wear, which seriously endanger the safety and efficiency of airfield operations and pose a safety hazard to aircraft takeoff and landing.

[0003] When the functional disease area of ​​the airport cement concrete pavement is large and the degree is high, the old pavement needs to be milled and cut, and then a new structural layer is laid for functional repair. Compared with the asphalt overlay, the cement concrete overlay is consistent with the old cement pavement material and has a longer functional service life. However, due to the insufficient bonding performance of the interface between the functional repair layer of the airport cement pavement and the old surface layer (that is, the interface between the new and old concrete of the airport pavement), the stress concentration effect at the interface is significant, which can easily cause structural damage and destruction at this location, resulting in a serious shortage of structural service life. Therefore, a technology for interlayer treatment of the interface between the new and old concrete of the airport pavement is needed to effectively treat and enhance the interlayer bonding performance and ensure its coordinated deformation and facility life. Summary of the invention

[0004] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art and to provide an interlayer adhesive and a treatment method for the interface between new and old concrete on airport pavements. The interlayer adhesive and the treatment method are suitable for surface paving after functional damage to airport cement concrete pavements, which solves the problem of insufficient bonding performance at the interface between new and old concrete on airport pavements, and improves the interlayer performance, structural toughness and service life of airport pavements after repair.

[0005] The object of the present invention is to overcome the deficiencies of the above-mentioned prior art and provide an interlayer adhesive for the interface between new and old concrete of airport pavements. The interlayer adhesive is a powdered polymer-modified cement mortar, comprising early-strength cement, silica fume, water, powdered polymer, basalt machine-made sand, polycarboxylic acid high-efficiency water-reducing agent and silicone defoaming agent. The mass of the powdered polymer is 1.4% to 2.2% of the mass of the early-strength cement; the solid content of the polycarboxylic acid high-efficiency water-reducing agent is 0.3% to 1.0% of the mass of the early-strength cement; the mass of the silica fume is 8-13% of the mass of the early-strength cement.

[0006] In the above technical solution, the powdered polymer is one or more of vinyl acetate-versatate vinyl ester, ethylene-vinyl acetate, and ethylene-acrylate.

[0007] In the above technical solution, the high-efficiency water reducing agent is a polycarboxylic acid powder water reducing agent, and the water reduction rate is not less than 35%; the organic defoaming agent is an organic silicon powder defoaming agent.

[0008] In the above technical solution, the basalt machine-made sand is blended according to particle sizes of 10-20 mesh and 40-70 mesh, and the blending percentages are 35%-45% and 55%-65% respectively.

[0009] In the above technical solution, the water-cement ratio is 0.27-0.31, and the sand-cement ratio is 1.0-1.4.

[0010] In the above technical solution, the silica fume is grade I silica fume.

[0011] In addition, the present invention also provides a method for interlayer treatment of the interface between new and old concrete of an airport pavement, the method comprising:

[0012] Calculate the influence of aircraft dynamic characteristics on the shear stress and tensile stress at the interface of the new and old pavement structures during takeoff, taxiing, turning and landing, and determine the limit value and position of interlayer failure stress;

[0013] Adjust the binder composition so that its strength is not lower than that of the new and old cement concrete, and at the same time can effectively increase the tensile stress and shear stress at the interface between the repair layer and the old layer to be higher than the most unfavorable range determined in step S1;

[0014] Milling, cutting and clearing the functional damaged area of ​​the airport cement concrete pavement, roughening the excavation interface of the damaged cement concrete pavement, and using a sweeper to treat the roughening residue on the interface, then sprinkling water on the excavation interface, and using a blower to treat the interface until there is no visible water on the surface;

[0015] Mix the interlayer adhesive powder bag with water, stir at high speed and then quickly place the adhesive in the cement mortar sprayer. Use a cement mortar sprayer to evenly spray the interlayer adhesive at the interface. When the surface of the interface agent is semi-dry, use early-strength and fast-hardening concrete for backfilling, rolling and paving, and cover and maintain the early-strength and fast-hardening concrete after initial setting.

[0016] In the above method, finite element analysis software is used to simulate the structural movement of the landing gear during aircraft landing, taxiing and turning through the beam stiffness unit and the fluid cavity model, and the influence range of the aircraft dynamic characteristics on the shear stress and tensile stress at the interface of the new and old pavement structures during takeoff, taxiing, turning and landing is calculated to determine the most unfavorable interface stress state.

[0017] The present invention has the following advantages:

[0018] (1) The present invention provides an interlayer treatment technology for the interface between new and old concrete of an airport pavement, which is suitable for enhancing the bonding performance of the interface between new and old concrete of an airport pavement, so that the new and old surface layers can serve as a whole under the influence of external loads and environmental factors, and further improve the structural toughness and service life of the airport surface structure after repair.

[0019] (2) Based on the mechanical analysis of the interface between the new and old concrete of the airport cement pavement, the present invention proposes treatment requirements and technical indicators applicable to the interface, guides the research and development of interlayer adhesive formulas, and effectively meets the demand for enhanced bonding performance between the new concrete overlay layer and the old cement concrete surface layer.

[0020] (3) The interlayer adhesive formula proposed in the present invention is composed of solids with stable chemical properties, which only needs to be mixed with water before construction, which is convenient for production and construction, and the construction effect is stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a flow chart of the interlayer treatment method for the interface between new and old concrete on airport pavement. DETAILED DESCRIPTION

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] The interlayer adhesive for the interface between new and old concrete of the airport pavement of the present invention is a powdered polymer modified cement mortar, which includes early strength cement, silica fume, water, powdered polymer, basalt machine-made sand, polycarboxylic acid high-efficiency water reducing agent and silicone defoaming agent, wherein the mass of the powdered polymer is 1.4% to 2.2% of the mass of the early strength cement, the solid content of the polycarboxylic acid high-efficiency water reducing agent is 0.3% to 1.0% of the mass of the early strength cement, the mass of the silica fume is 8-13% of the mass of the early strength cement, the water-binder ratio is 0.27 to 0.31 (binder is a cementitious material, and in this embodiment it is the sum of the masses of the early strength cement and the silica fume), and the sand-binder ratio is 1.0 to 1.4.

[0024] The powdered polymer used in this embodiment is one or more of vinyl acetate-versatate vinyl ester, ethylene-vinyl acetate, and ethylene-acrylate; the polycarboxylic acid high-efficiency water-reducing agent is a polycarboxylic acid powder water-reducing agent, and the water reduction rate is not less than 35%; the organic defoaming agent is an organic silicon powder defoaming agent, which is used to ensure the density of the layers; the basalt machine-made sand is blended according to the particle size of 10 mesh to 20 mesh and 40 to 70 mesh, and the blending percentages are 35% to 45% and 55% to 65% respectively.

[0025] like Figure 1 As shown, the method for treating the interface between new and old concrete on the airport pavement using the above-mentioned interlayer adhesive comprises the following steps:

[0026] S1. Mechanical analysis of the interface between new and old concrete based on airport cement pavement

[0027] This embodiment takes B777 and A380 large passenger aircraft as examples, and adopts finite element analysis software (such as Ls-dyna or Abaqus / Explicit) to simulate the structural motion form of the landing gear during aircraft landing, taxiing and turning through beam-rod stiffness units and fluid cavity models, calculates the influence range of the aircraft dynamic characteristics on the shear stress and tensile stress at the interface of the new and old pavement structures during takeoff, taxiing, turning and landing of B777 and A380 large passenger aircraft, and determines the limit value and position of the interlayer failure stress, that is, determines the most unfavorable interface stress state.

[0028] S2. Adjustment of interlayer adhesive configuration and performance testing

[0029] S2.1. Take the interlayer adhesive of the present invention and adjust the interlayer adhesive components so that the strength is not lower than the strength of the new and old concrete of the pavement. For example, the interlayer tensile strength and interlayer shear strength requirements of this embodiment are 3.5 MPa and 8 MPa.

[0030] S2.2. Select a test location and spray the interlayer adhesive adjusted in S2.1. Then use the core pull-out test and the interface shear test to respectively measure the interlayer tensile strength and interlayer shear strength of the new and old concrete after spraying the interlayer adhesive. If the requirements are met, that is, the interlayer tensile strength reaches more than 3.5MPa and the interlayer shear strength reaches more than 8MPa, then the interlayer adhesive component adjusted this time is selected; if the requirements are not met, then the interlayer adhesive component is readjusted until the measured strength meets the requirements.

[0031] The binder composition of this embodiment is regulated, specifically refers to regulating the polymer dosage, the type of single-mixed polymer, the water reducer dosage, and the defoamer dosage to meet the fluidity requirements, strength requirements, and bonding capacity requirements (interlayer tensile strength and interlayer shear resistance) required for spraying.

[0032] S3. Treatment of functional defects on the surface of airport cement concrete pavement

[0033] First, use a scanner to detect the runway surface, find cracks, wear and tear and other defects to determine the type of cement concrete pavement defects, the degree of damage and the specific damaged area. Secondly, the pavement with larger damaged areas and more serious damage is milled, and the pavement with smaller damaged areas and more serious damage is cut. Finally, the waste is removed after completing the above processes.

[0034] S4. Roughening and watering between the repair layer and the old surface layer

[0035] Use a roughening machine to roughen the old cement concrete pavement. After removing the waste generated by roughening, sprinkle water on the pavement. After treatment, use a blower to treat the surface until there is no visible water.

[0036] S5. Preparation and construction of interlayer adhesive

[0037] Select the interlayer adhesive configuration that meets the requirements in S2, use a light mortar mixer to mix the interlayer adhesive powder bag with water near the damaged area, stir at high speed for 3min to 4min, then quickly place the adhesive in a wheeled cement mortar sprayer, spray 2mm to 4mm of interlayer adhesive at the interface, and use a small roller to re-press the sprayed interface agent to ensure that the thickness of the interface agent is uniform.

[0038] In this embodiment, the main technical performance indicators of the powder polymer modified cement mortar interlayer binder after mixing are as follows:

[0039] ①Flowability: 185±10mm

[0040] ② Compressive strength: 7d and 28d compressive strengths are not less than 30MPa and 43MPa respectively.

[0041] ③ Flexural strength: 7d and 28d flexural strengths shall not be less than 7MPa and 9MPa respectively.

[0042] S6. Repair layer construction

[0043] When the interface agent reaches the surface half dry, pour the early strength and fast hardening concrete as the repair layer. After pouring and vibration, cover the concrete surface with film and maintain for 24 hours.

Claims

1. An interlayer adhesive for the interface between new and old concrete on airport pavements, characterized in that: The interlayer adhesive is a powdered polymer-modified cement mortar, which includes early-strength cement, silica fume, water, powdered polymer, basalt machine-made sand, polycarboxylic acid high-efficiency water-reducing agent and silicone defoaming agent. The mass of the powdered polymer is 1.4% to 2.2% of the mass of the early-strength cement; the solid content of the polycarboxylic acid high-efficiency water-reducing agent is 0.3% to 1.0% of the mass of the early-strength cement; and the mass of the silica fume is 8-13% of the mass of the early-strength cement.

2. The interlayer adhesive for the interface between new and old concrete of airport pavement according to claim 1, characterized in that: The powdered polymer is one or more of vinyl acetate-versatate vinyl ester, ethylene-vinyl acetate, and ethylene-acrylate.

3. The interlayer adhesive for the interface between new and old concrete of airport pavement according to claim 1, characterized in that: The polycarboxylic acid high-efficiency water reducing agent is a polycarboxylic acid series powder water reducing agent, and the water reduction rate is not less than 35%; the organic defoaming agent is an organic silicon powder defoaming agent.

4. The interlayer adhesive for the interface between new and old concrete of airport pavement according to claim 1, characterized in that: The basalt machine-made sand is blended according to particle sizes of 10-20 meshes and 40-70 meshes, and the blending percentages are 35%-45% and 55%-65% respectively.

5. The interlayer adhesive for the interface between new and old concrete of airport pavement according to claim 1, characterized in that: The water-cement ratio is 0.27-0.31, and the sand-cement ratio is 1.0-1.

4.

6. The interlayer adhesive for the interface between new and old concrete of airport pavement according to claim 5, characterized in that: The silica fume is grade I silica fume.

7. A method for interlayer treatment of the interface between new and old concrete on an airport pavement, characterized in that: include: Calculate the influence of aircraft dynamic characteristics on the shear stress and tensile stress at the interface of the new and old pavement structures during takeoff, taxiing, turning and landing, and determine the limit value and position of interlayer failure stress; Adjust the binder composition so that its strength is not lower than that of the new and old cement concrete, and at the same time can effectively increase the tensile stress and shear stress at the interface between the repair layer and the old layer to be higher than the most unfavorable range determined in step S1; Milling, cutting and clearing the functional damaged area of ​​the airport cement concrete pavement, roughening the excavation interface of the damaged cement concrete pavement, and using a sweeper to treat the roughening residue on the interface, then sprinkling water on the excavation interface, and using a blower to treat the interface until there is no visible water on the surface; Mix the interlayer adhesive powder bag with water, stir at high speed and then quickly place the adhesive in the cement mortar sprayer. Use a cement mortar sprayer to evenly spray the interlayer adhesive at the interface. When the surface of the interface agent is semi-dry, use early-strength and fast-hardening concrete for backfilling, rolling and paving, and cover and maintain the early-strength and fast-hardening concrete after initial setting.

8. The interlayer treatment method for the interface between new and old concrete of an airport pavement according to claim 7 is characterized in that: Finite element analysis software is used to simulate the structural movement of the landing gear during aircraft landing, taxiing and turning through the beam stiffness unit and the fluid cavity model. The influence of the aircraft dynamic characteristics on the shear stress and tensile stress at the interface between the new and old pavement structures during takeoff, taxiing, turning and landing is calculated to determine the most unfavorable interface stress state.

Images