Cement stabilized macadam base construction method
By optimizing the grading and cement dose of cement stabilized gravel mixture, a compact structure of the skeleton is formed, which solves the problem of temperature stress generated by cement stabilized gravel base under a large temperature difference environment, and achieves the improvement of the stability and service life of the base layer. .
Patent Information
- Application Number
- CN202411901403.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-23
- Publication Date
- 2025-02-11
AI Technical Summary
The existing cement-stable gravel base is prone to temperature stress in a large temperature difference environment, resulting in arches and cracks in the asphalt surface layer, which in turn causes premature damage to the road surface.
By optimizing the grading of cement and adjusting the cement dose, the maximum particle size of the gravel mixture is controlled to be between 35.0mm and 40.0mm, forming a compact structure of the skeleton to reduce the expansion coefficient, thereby preventing the amp swelling mass. Disease.
It effectively reduces the expansion and deformation of cement-stabilized gravel base, improves the stability of the base layer, extends the service life, and improves the anti-shrinkage ability of the road surface.
Smart Images
Figure CN119411437A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of road and bridge construction, and in particular to a cement-stabilized crushed stone base construction method. Background Art
[0002] During the project construction, the common road base material is cement-stabilized gravel. In the process of technological development, cement-stabilized gravel has become a commonly used road base material with the characteristics of large bearing capacity and good economic benefits. According to the distribution state of mineral materials in the mixture, the structural type of cement-stabilized gravel can be two types: suspended dense structure and skeleton dense structure. Among them, the skeleton dense structure absorbs the advantages of other structures and has better road performance, which provides an effective way for cement-stabilized gravel mixture to alleviate the above problems. In the actual use of cement-stabilized gravel base, cement-stabilized gravel has some disadvantages such as easy cracking and easy surface erosion. In addition, the problem of premature damage to the road surface caused by the defects of the cement-stabilized gravel base material itself is becoming more and more prominent.
[0003] The inventors found in their research that the cement stabilized gravel base in the prior art has at least the following disadvantages:
[0004] The existing cement-stabilized crushed stone adopts a four-grade continuous-graded suspended dense structure. The thermal expansion coefficient of the water-stabilized base is relatively large. Under the condition of large temperature difference and high cement dosage, the cement-stabilized crushed stone base produces huge temperature stress. When the temperature stress of the base is greater than the axial compressive strength (critical stress) or the arch displacement of the base is large, inclined cracks will occur. Under the continued action of high temperature weather, the base will expand freely along the cracks due to loss of restraint, arching the asphalt surface layer, thereby causing arching and cracking of the asphalt pavement. Summary of the invention
[0005] The objects of the present invention include, for example, providing a method for constructing a cement-stabilized gravel base, which can reduce the expansion coefficient of the cement-stabilized gravel mixture by optimizing the grading of the cement-stabilized gravel mixture and adjusting the cement dosage, thereby effectively preventing the quality defects of water-stabilized base arching under large temperature difference conditions.
[0006] The embodiments of the present invention can be implemented as follows:
[0007] In a first aspect, the present invention provides a cement-stabilized gravel base construction method, comprising the following steps:
[0008] Step s100, preparing a crushed stone mixture, and controlling the maximum particle size of the crushed stone mixture to be between 35.0 mm and 40.0 mm;
[0009] Step s200, mixing the graded crushed stone mixture and cement according to the designed proportion to form a cement-stabilized crushed stone mixture with a dense skeleton structure;
[0010] Step s300: Spread the cement-stabilized gravel mixture on the road surface and roll the spread layer.
[0011] In an optional embodiment, in the step s100, the maximum particle size of the crushed stone mixture is set to 37.5 mm.
[0012] In an optional embodiment, in the step s100, calculated by mass percentage, the proportion of crushed stones with a particle size between 0.075 mm and 0.6 mm in the crushed stone mixture is (3-6); the proportion of crushed stones with a particle size between 0.6 mm and 2.36 mm in the crushed stone mixture is (8-16); the proportion of crushed stones with a particle size between 2.36 mm and 4.75 mm in the crushed stone mixture is (20-28); the proportion of crushed stones with a particle size between 4.75 mm and 9.5 mm in the crushed stone mixture is (28-36); the proportion of crushed stones with a particle size between 9.5 mm and 19 mm in the crushed stone mixture is (38-46); the proportion of crushed stones with a particle size between 19 mm and 31.5 mm in the crushed stone mixture is (58-70); the proportion of crushed stones with a particle size between 31.5 mm and 37.5 mm in the crushed stone mixture is (88-100).
[0013] In an optional embodiment, in the step s100, the raw materials are screened using a sieve to obtain a crushed stone mixture of corresponding grade.
[0014] In an optional embodiment, in the step s200, the cement content is controlled to obtain a low-dose cement strong-embedded agent skeleton dense water-stabilized mixture, so that the compaction degree of the low-dose cement strong-embedded agent skeleton dense water-stabilized mixture is not less than 98%, and the crushing value of the coarse aggregate in the low-dose cement strong-embedded agent skeleton dense water-stabilized mixture is not more than 30%.
[0015] In an optional embodiment, in the step s200, the cement content is controlled between 3% and 4% by mass.
[0016] In an optional implementation, in step s200, a mixing plant is used to mix the cement and crushed stone mixture.
[0017] In an optional embodiment, in step s300, the mixed material is transported by a transport vehicle, and the transport vehicle reciprocates relative to the material outlet when containing the material, so as to reduce the probability of segregation of the cement-stabilized gravel mixture.
[0018] In an optional embodiment, in step s300, a paver is used to pave the mixture, and the probability of segregation of large-size water-stabilized mixture during paving is reduced by modifying the equipment, controlling the paving speed and the paving thickness. If the paving process is interrupted for more than 2 hours, a transverse construction joint is set at the edge of the paving layer.
[0019] In an optional embodiment, in step s300, when rolling a paving layer with a thickness greater than 30 cm, layered compaction is adopted, and the compaction thickness of each layer is set at 15-20 cm; for a paving layer with a thickness of 20 cm-25 cm, one-time compaction is adopted.
[0020] The beneficial effects of the embodiments of the present invention include, for example:
[0021] In summary, the cement-stabilized gravel base construction method provided in the present embodiment controls the maximum particle size of the gravel mixture to be between 35.0 mm and 40.0 mm, which increases the size of the maximum particle size compared to the prior art method, so that the gradation of the cement-stabilized gravel mixture is coarser, and the interlocking effect between the aggregates is enhanced, thereby weakening the expansion and deformation of the mixture; at the same time, due to the coarse gradation, the internal porosity of the coarse aggregate in the gravel mixture can be increased, thereby providing space to accommodate the volume expanded due to temperature stress, thereby improving the stability of the base, and the base is not easy to bulge and crack during service, thereby improving the safety of use and extending the service life. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.
[0023] Figure 1 This is a schematic diagram of the process of the cement-stabilized gravel base construction method of the embodiment of the present application. DETAILED DESCRIPTION
[0024] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.
[0025] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0026] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.
[0027] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear to indicate an orientation or position relationship, they are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the product of the invention is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.
[0028] In addition, the terms “first”, “second”, etc., if used, are merely used to distinguish between the descriptions and should not be understood as indicating or implying relative importance.
[0029] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.
[0030] In the prior art, during the actual use of cement-stabilized gravel base, such materials have some disadvantages such as easy cracking and easy surface erosion, and the problem of premature road damage caused by the defects of the cement-stabilized gravel base material itself is becoming increasingly prominent. The arching and cracking mechanism of asphalt pavement is as follows: under high temperature conditions, the cement-stabilized gravel base produces huge temperature stress. When the temperature stress of the base is greater than the axial compressive strength or the arch displacement of the base is large, inclined cracks will be generated. Under the continued action of high temperature weather, the base will expand freely along the cracks due to the loss of constraints, arching the asphalt surface layer, thereby causing arching and cracking of the asphalt pavement.
[0031] In view of this, the designer provides a cement-stabilized gravel base construction method. By optimizing the grading of water-stabilized gravel and adjusting the cement dosage, the expansion coefficient of cement-stabilized gravel is reduced, thereby preventing the quality disease of arching of the water-stabilized base under large temperature difference conditions.
[0032] Please combine Figure 1 In this embodiment, the cement stabilized gravel base construction method includes the following steps:
[0033] Step s100, preparing a crushed stone mixture, and controlling the maximum particle size of the crushed stone mixture to be between 35.0 mm and 40.0 mm.
[0034] Step s200: Mix the graded crushed stone mixture and cement according to the designed ratio to form a cement-stabilized crushed stone mixture with a dense skeleton structure.
[0035] Step s300: Spread the cement-stabilized gravel mixture on the road surface and roll the spread layer.
[0036] As described above, the cement stabilized gravel base construction method provided in this embodiment has at least the following advantages:
[0037] By controlling the maximum particle size of the crushed stone mixture between 35.0 mm and 40.0 mm, the maximum particle size is increased compared to the prior art method, so that the gradation of the cement-stabilized crushed stone mixture is coarser, and the interlocking effect between the aggregates is enhanced, thereby weakening the expansion and deformation of the mixture; at the same time, due to the coarse gradation, the internal porosity of the coarse aggregate in the crushed stone mixture can be increased, thereby providing space to accommodate the volume expanded due to temperature stress, thereby improving the stability of the base layer, making it less likely to bulge and crack during service, thereby improving safety in use and extending service life.
[0038] The following embodiments illustrate the details of the cement-stabilized gravel base construction method of the present application by way of examples.
[0039] In this embodiment, optionally, in step s100, the maximum particle size of the crushed stone mixture is set to 37.5 mm. That is, compared with the prior art, the maximum particle size of the crushed stone mixture is increased from the original 26.5 mm to 37.5 mm, the gradation of the mixture is coarser, and the interlocking effect between the coarse aggregate and the fine aggregate is stronger, thereby weakening the collision deformation.
[0040] It should be understood that in other embodiments, the maximum particle size of the crushed stone mixture can also be set to 35.0 mm or 40.0 mm, etc., which can be selected as needed and are not listed one by one in this embodiment.
[0041] In an optional embodiment, in step s100, calculated by mass percentage, the proportion of crushed stones with a particle size between 0.075 mm and 0.6 mm in the crushed stone mixture is (3-6); the proportion of crushed stones with a particle size between 0.6 mm and 2.36 mm in the crushed stone mixture is (8-16); the proportion of crushed stones with a particle size between 2.36 mm and 4.75 mm in the crushed stone mixture is (20-28); the proportion of crushed stones with a particle size between 4.75 mm and 9.5 mm in the crushed stone mixture is (15-28); The proportion of crushed stone in the crushed stone mixture is (28-36); the proportion of crushed stone with a particle size between 9.5mm-19mm in the crushed stone mixture is (38-46); the proportion of crushed stone with a particle size between 19mm-31.5mm in the crushed stone mixture is (58-70); the proportion of crushed stone with a particle size between 31.5mm-37.5mm in the crushed stone mixture is (88-100). In this way, the particle size of the crushed stone mixture is controlled below 37.5mm, and the maximum particle size does not exceed 37.5mm.
[0042] It should be noted that in step s100, the raw materials are screened using a screen to obtain a crushed stone mixture of corresponding grade. It should be understood that the screen can be set to a multi-layer structure, and the mesh diameter of each screen gradually decreases from top to bottom. For example, during operation, the crushed gravel is placed on the topmost screen, and the crushed stones less than or equal to 37.5 mm can fall from the topmost screen and fall onto the second screen. Under the screening effect of the second screen, the crushed stones with a particle size between 31.5 mm and 37.5 mm stay on the second screen. The crushed stones less than or equal to 31.5 mm fall from the second screen to the third screen, and so on. Each screen can obtain the corresponding particle size of the crushed stones, and the multi-level crushed stones are matched in proportion to obtain the crushed stone mixture of corresponding grade.
[0043] It should be understood that when carrying out multi-grade proportioning, the crushed stone mixture is mixed by discontinuous grading.
[0044] In this embodiment, optionally, in step s200, the cement content is controlled to obtain a low-dose cement strong embedding agent skeleton dense water-stabilized mixture, so that the compaction degree of the low-dose cement strong embedding agent skeleton dense water-stabilized mixture is not less than 98%, and the crushing value of the coarse aggregate in the low-dose cement strong embedding agent skeleton dense water-stabilized mixture is not more than 30%. For example, according to the mass percentage, the cement content is controlled between 3%-4%, and optionally, the cement content can be controlled at 3%, 3.5% or 4%, etc. It is known from the test data that in the same temperature range, the deformation of the crushed stone mixture increases with the increase of the cement dosage, and the expansion coefficient also increases accordingly. The cement cements the aggregates together to form a stable structure so that the aggregates cannot move freely. When the temperature rises, the aggregates will move in one direction uniformly, thereby causing displacement. The larger the cement dosage, the greater the overall displacement of the aggregates at the same temperature difference, and thus the greater the expansion coefficient. Cement-stabilized gravel mixture is a temperature-sensitive material, and its expansion property changes with temperature. Its expansion property is strongest and its expansion coefficient is largest in the temperature range of 40°C to 50°C. Therefore, in this embodiment, the amount of expansion deformation can be effectively improved by controlling the cement content between 3% and 4%.
[0045] It should be understood that cement and gravel mixture can be mixed in a mixing plant. In actual operation, computer control can be used to realize automatic control of the mixing plant, and the mixing materials can be batched in different hoppers. The control room of the mixing plant can use a controller to control the loading, mixing and unloading of the entire mixing plant. When the first bucket of materials is loaded after the mixing plant is opened, its appearance quality is checked. If uneven mixing is found, the unqualified mixture will be discarded, and the second bucket of mixture will be checked again until the mixing is uniform and the quality is stable and reliable. The mixer is used to directly load the dump truck. The vehicle moves forward and backward during loading, that is, the vehicle reciprocates relative to the discharge port during loading. The material can be loaded in multiple times to avoid segregation of the mixture.
[0046] In this embodiment, optionally, in step s300, after the cement-stabilized gravel mixture is obtained by mixing, the cement-stabilized mixture can be transported to the site for paving operations by vehicles. During transportation, the vehicle type can be selected according to demand, and the materials need to be mixed during the transportation process. During on-site construction, the mixture is spread by a paver, and if the paving process is interrupted for more than 2 hours, a transverse construction joint is set at the edge of the paving layer. The transverse construction joint facilities meet the requirements of the specifications, and before resuming paving the mixture, remove the debris and clean it up.
[0047] In this embodiment, optionally, in step s300, when rolling a paving layer with a thickness greater than 30 cm, layered compaction is adopted, and the compaction thickness of each layer is set at 15-20 cm; for a paving layer with a thickness set at 20 cm-25 cm, one-time compaction is adopted.
[0048] After paving and shaping, the base mixture of low-cement-dosage water-stable crushed stone mixture is rolled over the entire width. The rolling follows the principle of low first and high later, light first and heavy later. The base is rolled from both sides to the middle, and each rolling overlaps the previous rolling by 1 / 3 of the wheel width. First, use a tire roller to statically press once, then use a vibrating roller to perform low vibration once, high vibration 4 times, low vibration 1 time, and finally use a rubber-wheeled roller to statically press the surface. Rolling is carried out according to the rolling sequence and number of times summarized in the test section. During the rolling process, the compaction degree is tracked and tested to determine the reasonable number of rolling times. If necessary, the number of rolling times is increased. After rolling, the wheel marks on the surface of the water-stable base are removed, and the uneven surface is repaired. If there is a "nest aggregate belt" phenomenon of coarse and fine aggregates, it must be dug and refilled. After inspection, after 2 low vibrations and 4-5 high vibrations, the compaction degree can meet the requirements.
[0049] It should be understood that after paving is completed, the road surface is maintained. Before the rolling operation is completed, if there is water loss due to excessive temperature and strong wind that affects compaction, timely water replenishment measures should be taken to carry out curing and traffic management; after rolling is completed and the cement-stabilized gravel has finally set, the geotextile is covered and water is sprayed from the side by a water truck for curing. The geotextile is pressed with a snakeskin bag filled with sand and soil blocks. The curing period is about 7 days. After the strength meets the design requirements, the second layer of paving and the next process are carried out.
[0050] The cement stabilized gravel base construction method provided in this embodiment uses a low-dose cement strong embedded skeleton dense water-stabilized construction, and then tests the compaction degree, deflection and other aspects of the base top surface to meet the relevant requirements of the Technical Specifications for Highway Pavement Base Construction (JTGTF20-2015) and the Highway Engineering Quality Inspection and Assessment Standard (JTGF80 / 1-2017). In addition, the low-dose cement strong embedded skeleton dense water-stabilized crushed gravel base mixture should be tested with the 14d unconfined compressive strength after 13d of moisture curing at the specified temperature and 1d of immersion in water as the test value, which should meet the standard value of unconfined compressive strength at 7d age in the "Technical Specifications for Highway Pavement Base Construction" (JTG / TF20-2015). After the curing period of the upper base of the dense skeleton cement stabilized gravel was completed, the road was opened to traffic. After a period of time, a large number of heavy-loaded construction vehicles passed through. It was observed that there were no loose particles on the surface, with good anti-scouring ability. The gravel distribution on the surface of the base was relatively uniform, densely embedded, without large gaps, and the strength was good after testing. No cracks appeared on the road surface after observation. Under the condition of large temperature difference, during the high temperature period in the summer of the second year after the construction of the asphalt concrete pavement, the asphalt concrete pavement did not suffer from the quality disease of lateral arching of the pavement caused by the arching of the water-stabilized base.
[0051] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.
Claims
1. A cement stabilized gravel base construction method, characterized in that: The steps include: Step s100, preparing a crushed stone mixture, and controlling the maximum particle size of the crushed stone mixture to be between 35.0 mm and 40.0 mm; Step s200, mixing the graded crushed stone mixture and cement according to the designed proportion to form a cement-stabilized crushed stone mixture with a dense skeleton structure; Step s300: Spread the cement-stabilized gravel mixture on the road surface and roll the spread layer.
2. The cement-stabilized crushed stone base construction method according to claim 1 is characterized in that: In the step s100, the maximum particle size of the crushed stone mixture is set to 37.5 mm.
3. The cement-stabilized macadam base construction method according to claim 1 is characterized in that: In the step s100, calculated by mass percentage, the proportion of crushed stones with a particle size between 0.075 mm and 0.6 mm in the crushed stone mixture is (3-6); the proportion of crushed stones with a particle size between 0.6 mm and 2.36 mm in the crushed stone mixture is (8-16); the proportion of crushed stones with a particle size between 2.36 mm and 4.75 mm in the crushed stone mixture is (20-28); the proportion of crushed stones with a particle size between 4.75 mm and 9.5 mm in the crushed stone mixture is (28-36); the proportion of crushed stones with a particle size between 9.5 mm and 19 mm in the crushed stone mixture is (38-46); the proportion of crushed stones with a particle size between 19 mm and 31.5 mm in the crushed stone mixture is (58-70); and the proportion of crushed stones with a particle size between 31.5 mm and 37.5 mm in the crushed stone mixture is (88-100).
4. The cement-stabilized crushed stone base construction method according to claim 1 is characterized in that: In the step s100, the raw materials are screened by using a screen to obtain a crushed stone mixture of corresponding grade.
5. The cement-stabilized crushed stone base construction method according to claim 1 is characterized in that: In the step s200, the cement content is controlled to obtain a low-dose cement strong-embedded agent skeleton dense water-stabilized mixture, so that the compaction degree of the low-dose cement strong-embedded agent skeleton dense water-stabilized mixture is not less than 98%, and the crushing value of the coarse aggregate in the low-dose cement strong-embedded agent skeleton dense water-stabilized mixture is not more than 30%.
6. The cement-stabilized macadam base construction method according to claim 5 is characterized in that: In the step s200, the cement content is controlled between 3% and 4% by mass.
7. The cement-stabilized crushed stone base construction method according to claim 1 is characterized in that: In step s200, a mixing plant is used to mix the cement and crushed stone mixture.
8. The cement-stabilized crushed stone base construction method according to claim 1 is characterized by: In the step s300, the mixed material is transported by a transport vehicle, and the transport vehicle reciprocates relative to the material outlet when containing the material, so as to reduce the probability of segregation of the cement-stabilized crushed stone mixture.
9. The cement-stabilized crushed stone base construction method according to claim 1, characterized in that: In step s300, a paver is used to spread the mixture. During the paving process, the probability of segregation of large-size water-stabilized mixture during paving is reduced by modifying the equipment, controlling the paving speed and the paving thickness. If the paving process is interrupted for more than 2 hours, a transverse construction joint is set at the edge of the paving layer.
10. The cement stabilized macadam base construction method according to claim 1, characterized in that: In the step s300, when rolling a paving layer with a thickness greater than 30 cm, layered compaction is adopted, and the compaction thickness of each layer is set at 15-20 cm; for a paving layer with a thickness of 20 cm-25 cm, one-time compaction is adopted.