Construction method for expansion joint of cement-stabilized gravel base in cold region

Abstract

The invention belongs to a construction method for an expansion joint of a cement stabilized gravel base in a cold region, which comprises the following steps of: longitudinally cutting the expansion joint of the cement stabilized gravel base by using cutting equipment to form segmented plates, and filling the joint by using flexible asphalt to realize free expansion and contraction of each plate; by means of high tensile strength and low elongation of the concrete plate and the glass fiber geogrid cloth, stability can be kept when the plates are stressed, and excessive deformation is not prone to being caused; and meanwhile, a plurality of temperature equalizing holes are formed in each plate, so that the temperatures of the upper and lower parts in each plate tend to be consistent, and cracks caused by inconsistent tensile stress in the material due to non-uniform temperatures of the upper and lower parts of the cement stabilized gravel base are prevented. The method provided by the invention can effectively reduce the occurrence of cement-stabilized gravel base cracks caused by overlarge shrinkage stress in cold regions.

Description

Technical Field

[0001] The invention belongs to a method for constructing expansion joints in a cement-stabilized gravel base layer in cold regions. Background Art

[0002] The highway pavement is composed of 15cm thick crushed stone as the subbase, and a 34cm thick cement-stabilized gravel base is set on the top of the subbase. Then, a total of 19cm thick asphalt surface layers are laid on the top of the cement-stabilized gravel base. The cement-stabilized gravel base plays a connecting role. The integrity, strength, and compaction of the cement-stabilized gravel base play a key role in the quality of the highway. The cement-stabilized gravel base belongs to a semi-rigid base. On highways in cold northern regions, asphalt pavement cracks caused by shrinkage cracks caused by temperature changes in the semi-rigid cement-gravel stabilized base are particularly common, and seriously affect the quality of highway operations. This is because the semi-rigid cement-gravel stabilized base is sensitive to temperature changes, and thermal expansion and contraction will cause the tensile stress inside the material to exceed its ultimate tensile strength, thereby causing cracks.

[0003] Therefore, how to solve the problem of asphalt pavement cracks caused by shrinkage cracks caused by temperature changes in semi-rigid cement gravel stabilized base in cold northern regions, which affects the operation quality of highways, is an urgent problem that needs to be solved. Summary of the invention

[0004] The purpose of the present invention is to design a construction method for expansion joints in cement-stabilized gravel base in cold regions to solve the above problems.

[0005] To this end, the present invention provides a method for constructing expansion joints in a cement-stabilized gravel base in cold regions, comprising the following steps: (1) After the construction of the cement-stabilized gravel base of the highway is completed, a grooving device shall be used to open a horizontal expansion joint that cuts off the cement-stabilized gravel base every 50 to 60 m in the longitudinal pavement of the cement-stabilized gravel base in the wet area and every 90 to 110 m in the longitudinal pavement of the cement-stabilized gravel base in the dry area; (2) A 4-5 cm deep transverse groove is provided downward on the upper end of the cement-stabilized gravel base 25-30 cm outward on both sides of the expansion joint; (3) Use high-pressure gas from an air compressor to clean the debris in the expansion joint and the lower transverse groove; (4) preparing flexible asphalt, heating the flexible asphalt into a liquid state, and filling the expansion joint with the liquid flexible asphalt until it is parallel to the bottom surface of the lower transverse groove; (5) A concrete slab with a thickness equal to the depth of the lower transverse groove is placed in the middle of the lower transverse groove, and the distance between the two ends of the concrete slab and the inner side of the lower transverse groove on the corresponding side is 2 cm to form an expansion joint in the lower transverse groove; (6) Fill the expansion joint inside the lower transverse groove with liquid flexible asphalt until it is parallel to the upper end surface of the lower transverse groove; (7) In each cement-stabilized gravel base plate divided by expansion joints, a temperature-equalizing hole with a diameter of 3 to 4 cm is drilled every 10 m in the longitudinal direction, and the bottom of the temperature-equalizing hole is 2 to 3 cm away from the lower end surface of the cement-stabilized gravel base; (8) Insert a temperature-averaging tube into the temperature-averaging hole; (9) Lay asphalt surface layer on the cement-stabilized gravel base, concrete slab and upper end of the temperature-equalizing pipe to complete the highway pavement construction; Or lay 1 to 3 layers of fiberglass geogrid cloth on the upper end surface of the lower horizontal groove and the concrete slab, and extend both sides of the fiberglass geogrid cloth to 30 to 35 cm outside the expansion joint in the lower horizontal groove, and lay asphalt surface layer on the cement stabilized gravel base, concrete slab and the upper end surface of the temperature equalizing pipe to complete the highway pavement construction.

[0006] As a further description of the above technical solution: the width of the expansion joint is 2 to 2.5 cm, and the depth penetrates the upper and lower end surfaces of the cement stabilized gravel base.

[0007] As a further description of the above technical solution: the flexible asphalt is a mixed material of asphalt and waste rubber particles, the weight ratio of asphalt to waste rubber particles is 100:20-25, and the particle size of the waste rubber particles is 1-4 mm.

[0008] As a further description of the above technical solution: the grid holes of the glass fiber geogrid cloth are 2×2 cm.

[0009] As a further description of the above technical solution: the cement-stabilized gravel base layer in the wet zone is a cement-stabilized gravel base layer near a swamp, a water surface and a riverside road section.

[0010] As a further description of the above technical solution: the grooving equipment includes a rock saw cutting machine.

[0011] As a further description of the above technical solution: the concrete slab can be a plurality of concrete slabs connected end to end.

[0012] As a further description of the above technical solution: the temperature-averaging pipe is a steel pipe or a glass fiber cement pipe with an outer diameter that matches the inner diameter of the temperature-averaging hole. The pipe wall is densely covered with through holes at intervals, and at least the upper end of the pipe is closed.

[0013] As a further description of the above technical solution: adjacent temperature-averaging holes are staggered in the longitudinal direction.

[0014] The present invention has the following beneficial effects: 1. The method of the present invention can effectively prevent the problem of broken boards caused by excessive shrinkage stress in cement-stabilized gravel base in cold regions, avoid the irregular cracks of cement-stabilized gravel base reflecting to the asphalt surface layer and affecting the road surface structure layer, and improve the durability and safety of the road surface. The present invention uses cutting equipment to cut expansion joints in cement-stabilized gravel base to form divided boards, which can ensure the thickness and width of the cut joints. At the same time, flexible asphalt is used for filling the joints to achieve free expansion and contraction of each board, and the high tensile strength and low elongation of concrete boards and glass fiber geogrid cloths are used to enable each board to maintain stability when subjected to stress and not easily cause excessive deformation; and at the same time, a number of temperature-equalizing holes are set in each board to make the upper and lower temperatures of each board tend to be consistent, so as to prevent the upper and lower parts of the cement-stabilized gravel base from causing inconsistent tensile stress inside the material due to uneven temperatures, thereby causing cracks.

[0015] Practical road sections have proved that the method of the present invention can effectively reduce the occurrence of cracks in cement-stabilized gravel base layers caused by excessive shrinkage stress in cold regions, and eliminate the occurrence of vertical cracks within 100 meters on the surface of cement-stabilized gravel base layers caused by traditional methods, achieving no cracks within 1,000 meters, and enabling cement-stabilized gravel base layers to meet high quality standards.

[0016] 2. The invention is simple to operate, highly practical, has obvious effect, fast construction speed, saves time and effort, and has stable and safe construction, excellent quality, good use effect and good economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of the longitudinal cross-sectional structure of the present invention; Figure 2 It is another schematic diagram of the longitudinal cross-sectional structure of the present invention; Figure 3 for Figure 2 AA section diagram; Figure 4 It is a schematic diagram of the temperature equalizing tube structure of the present invention. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described in conjunction with specific embodiments below, but the following embodiments are only preferred embodiments of the present invention, not all. Based on the embodiments in the implementation mode, other embodiments obtained by those skilled in the art without creative work all belong to the protection scope of the present invention. The construction methods in the following embodiments, unless otherwise specified, are all conventional methods. The materials, devices, equipment, etc. used in the following embodiments, unless otherwise specified, can all be obtained from commercial channels.

[0019] Example 1: Figures 1 to 4 As shown, a method for constructing expansion joints of cement-stabilized gravel base in cold regions comprises the following steps: (1) The highway pavement is composed of a 15 cm thick crushed stone subbase 3, a 34 cm thick cement stabilized gravel base 2 is set on the top of the subbase 3, and then a 19 cm thick asphalt surface layer 1 is laid on the top of the cement stabilized gravel base. After the construction of the highway cement stabilized gravel base 2 is completed, a grooving device is used to open a horizontal expansion joint 4 that cuts off the cement stabilized gravel base every 50 to 60 m in the longitudinal pavement of the cement stabilized gravel base in the wet area and every 90 to 110 m in the longitudinal pavement of the cement stabilized gravel base in the dry area. The width of the expansion joint is 2 to 2.5 cm, and the depth runs through the upper and lower end surfaces of the cement stabilized gravel base. The function of the expansion joint 4 is to leave expansion space for the thermal expansion and contraction of the cement stabilized gravel base in cold areas.

[0020] The cement stabilized gravel base in the wet area is the cement stabilized gravel base near the swamp, water surface and riverside road section, and the cement stabilized gravel base in the dry area is the cement stabilized gravel base. Grooving equipment includes rock saw cutting machine.

[0021] (2) A 4-5 cm deep transverse lower groove 6 is provided downwardly on the upper end surface of the cement stabilized gravel base 25-30 cm outwardly from both sides of the expansion joint 4, and the expansion joint 4 is located in the middle of the lower bottom surface of the transverse lower groove 6.

[0022] (3) Use the high-pressure gas from the air compressor to clean the debris in the expansion joint and the lower horizontal groove.

[0023] (4) Prepare flexible asphalt 5 as the filler of the expansion joint, heat the flexible asphalt into a liquid state, and fill the expansion joint with the liquid flexible asphalt until it is parallel to the bottom surface of the lower transverse groove. Flexible asphalt 5 is a mixed material of asphalt and waste rubber particles, the weight ratio of asphalt to waste rubber particles is 100:20-25, and the particle size of the waste rubber particles is 1-4 mm; when used, take 100 kg of asphalt and place it in a heating container with a stirring device, heat it to 150°C-180°C to form a liquid state, and then add 20-25 kg of waste rubber particles with a particle size of 1-4 mm to the hot liquid asphalt, stir evenly, and form liquid flexible asphalt.

[0024] (5) A concrete slab 7 having the same thickness as the depth of the lower transverse groove is placed in the middle of the lower transverse groove 6, and the length of the inner side of the lower transverse groove on the corresponding side of the two ends of the concrete slab 7 is 2 cm, forming an expansion joint 4 in the lower transverse groove. The function of the concrete slab 7 is to balance the pressure at the upper end of the expansion joint. The concrete slab 7 can be a plurality of concrete slabs connected end to end, and each concrete slab 7 has a length of 1.2 m and a width less than the width of the lower transverse groove of 4 cm.

[0025] (6) Fill the expansion joint 4 in the lower transverse groove with liquid flexible asphalt 5 until it is parallel to the upper end surface of the lower transverse groove.

[0026] (7) In each cement-stabilized gravel base block divided by an expansion joint, a temperature-equalizing hole 9 with a diameter of 3 to 4 cm is drilled every 10 m in the longitudinal direction of the road. The depth of the temperature-equalizing hole 9 is 31 to 32 cm, and the bottom surface of the temperature-equalizing hole 9 is 2 to 3 cm away from the lower end surface of the cement-stabilized gravel base. The function of the temperature-equalizing hole 9 is to make the upper and lower parts of each block of the cement-stabilized gravel base plate tend to be consistent, so as to prevent the upper and lower parts of the cement-stabilized gravel base from having inconsistent tensile stress inside the material due to uneven temperature, thereby generating cracks. Adjacent temperature-equalizing holes are staggered in the longitudinal direction, that is, adjacent temperature-equalizing holes are located on both sides of the road center line 10, so as to facilitate the temperature equalization of the upper and lower ends of the cement-stabilized gravel base.

[0027] (8) A temperature-equalizing pipe is placed in the temperature-equalizing hole. The temperature-equalizing pipe 11 is a steel pipe or a glass fiber cement pipe whose outer diameter matches the inner diameter of the temperature-equalizing hole. Through holes 12 are densely distributed on the pipe wall at intervals, and at least the upper end of the pipe mouth is closed. The function of the temperature-equalizing pipe is to make the upper and lower temperatures of each block of the cement-stabilized gravel base tend to be consistent.

[0028] (9) Lay asphalt surface layer on the cement-stabilized gravel base, concrete slab and upper end surface of the temperature-equalizing pipe to complete the highway pavement construction.

[0029] Embodiment 2: The difference from Embodiment 1 is that in step (9) of Embodiment 1: 1 to 3 layers of glass fiber geogrid cloth 8 are laid on the upper end surface of the lower transverse groove and the concrete slab, and the two sides of the glass fiber geogrid cloth are extended to 30 to 35 cm outside the expansion joint in the lower transverse groove, and an asphalt surface layer is laid on the cement stabilized gravel base, the concrete slab and the upper end surface of the temperature equalizing pipe to complete the highway pavement construction. The grid holes of the glass fiber geogrid cloth 8 are 2×2 cm. The function of the glass fiber geogrid cloth 8 is to enable each plate to maintain stability when subjected to force and not easily cause excessive deformation. The rest is the same as Embodiment 1, so it will not be repeated.

[0030] What is described above is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for constructing expansion joints on cement-stabilized gravel base in cold regions, characterized in that: The steps include: (1) After the construction of the cement-stabilized gravel base of the highway is completed, a grooving device shall be used to open a horizontal expansion joint that cuts off the cement-stabilized gravel base every 50 to 60 m in the longitudinal pavement of the cement-stabilized gravel base in the wet area and every 90 to 110 m in the longitudinal pavement of the cement-stabilized gravel base in the dry area; (2) A 4-5 cm deep transverse groove is provided downward on the upper end of the cement-stabilized gravel base 25-30 cm outward on both sides of the expansion joint; (3) Use high-pressure gas from an air compressor to clean the debris in the expansion joint and the lower transverse groove; (4) preparing flexible asphalt, heating the flexible asphalt into a liquid state, and filling the expansion joint with the liquid flexible asphalt until it is parallel to the bottom surface of the lower transverse groove; (5) A concrete slab with a thickness equal to the depth of the lower transverse groove is placed in the middle of the lower transverse groove, and the distance between the two ends of the concrete slab and the inner side of the lower transverse groove on the corresponding side is 2 cm to form an expansion joint in the lower transverse groove; (6) Fill the expansion joint inside the lower transverse groove with liquid flexible asphalt until it is parallel to the upper end surface of the lower transverse groove; (7) In each cement-stabilized gravel base plate divided by expansion joints, a temperature-equalizing hole with a diameter of 3 to 4 cm is drilled every 10 m in the longitudinal direction, and the bottom of the temperature-equalizing hole is 2 to 3 cm away from the lower end surface of the cement-stabilized gravel base; (8) Insert a temperature-averaging tube into the temperature-averaging hole; (9) Lay asphalt surface layer on the cement-stabilized gravel base, concrete slab and upper end of the temperature-equalizing pipe to complete the highway pavement construction; Or lay 1 to 3 layers of fiberglass geogrid cloth on the upper end surface of the lower horizontal groove and the concrete slab, and extend both sides of the fiberglass geogrid cloth to 30 to 35 cm outside the expansion joint in the lower horizontal groove, and lay asphalt surface layer on the cement stabilized gravel base, concrete slab and the upper end surface of the temperature equalizing pipe to complete the highway pavement construction.

2. The method according to claim 1, characterized in that: The width of the expansion joint is 2-2.5 cm, and the depth penetrates the upper and lower end surfaces of the cement stabilized gravel base.

3. The method according to claim 1, characterized in that: The flexible asphalt is a mixed material of asphalt and waste rubber particles, the weight ratio of asphalt to waste rubber particles is 100:20-25, and the particle size of the waste rubber particles is 1-4 mm.

4. The method according to claim 1, characterized in that: The grid holes of the glass fiber geogrid cloth are 2×2 cm.

5. The method according to claim 1, characterized in that: The cement-stabilized gravel base layer in the wet zone is a cement-stabilized gravel base layer near a swamp, a water surface and a riverside road section.

6. The method according to claim 1, characterized in that: The slotting equipment includes a rock saw cutting machine.

7. The method according to claim 1, characterized in that: The concrete slab can be a plurality of concrete slabs connected end to end.

8. The method according to claim 1, characterized in that: The temperature-averaging pipe is a steel pipe or a glass fiber cement pipe whose outer diameter matches the inner diameter of the temperature-averaging hole. Through holes are densely distributed on the pipe wall at intervals, and at least the upper end of the pipe opening is closed.

9. The method according to claim 1, characterized in that: Adjacent temperature-averaging holes are staggered in the longitudinal direction.

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