A large-particle-size anti-cracking cement stabilized material, a preparation method and an application method

Abstract

The application provides a large-granularity anti-crack cement stabilized material, a preparation method and an application method. The cement stabilized material comprises cement, TBM tunneling material, externally added fine aggregate, externally added coarse aggregate, polypropylene fiber, magnesium anti-crack agent and water; the cement is used in an amount of 50-150 kg / m 3 , the TBM tunneling material is used in an amount of 1250-2500 kg / m 3 , the externally added fine aggregate is 0-1250 kg / m 3 , the externally added coarse aggregate is 0-1250 kg / m 3 , the polypropylene fiber is 0.05-0.10 kg / m 3 , the magnesium anti-crack agent is used in an amount of 1.0-4.5 kg / m 3 , and the water is used in an amount of 30-150 kg / m 3 . The application can solve the treatment problem of the TBM tunneling material and the quality problem of cracks easily generated in the water stabilized layer of the highway base layer or the bottom base layer.

Description

Technical Field

[0001] This invention relates to the field of road construction materials technology, and in particular to a large-particle-size crack-resistant cement stabilizer, its preparation method, and its application method. Background Technology

[0002] TBM construction technology, as the most advanced tunnel construction technology, has been widely used in tunnel engineering construction in industries such as railways, highways, and hydropower. Compared with the drill-and-blast method, which has disadvantages such as difficulty in quality control, low level of mechanization, large labor input, high safety risks, long construction period, and poor working environment, which can easily cause occupational health damage to on-site construction and management personnel and lead to safety accidents, TBM construction technology has shown outstanding advantages in terms of quality, construction period, safety, environmental protection and civilized construction.

[0003] TBM construction generates a large amount of excavated material, which has a large particle size and discontinuous particle size distribution. Currently, in most projects, TBM excavated material is treated as waste, which requires large areas of land for dumping. This not only occupies land resources but also poses safety hazards if not handled properly, and causes environmental pollution and ecological damage. Furthermore, waste disposal increases project costs. If this material can be utilized rationally, it can not only reduce the land area occupied by waste and improve the economic efficiency of the project but also protect the ecological environment.

[0004] Furthermore, cement-stabilized materials are prone to cracking due to raw material and construction factors. Cracks can damage the integrity of the pavement structure, reduce load-bearing capacity, lower road quality, affect the service life of the project, endanger traffic safety, and even render the road unusable. Repairing these cracks can incur significant economic burdens. For large-diameter cement-stabilized materials, the maximum particle size in indoor compaction testing equipment is limited to 40mm. Therefore, the original gradation needs to be technically modified before compaction testing can be conducted. Consequently, the obtained maximum dry density is lower than that at the construction site, resulting in a compaction degree far exceeding the design requirements after on-site filling and rolling, sometimes even exceeding 100%. The actual compaction degree may be substandard, failing to reflect the true compaction quality at the construction site. This can easily induce cracking and leave hidden quality problems in the project. Summary of the Invention

[0005] The purpose of this invention is to provide a large-particle-size crack-resistant cement stabilized material, its preparation method, and its application method, thereby solving the problem of TBM tunnel excavation material processing and the quality problem of easy cracking in the water-stabilized layer of highway base or subbase.

[0006] To achieve the objectives of this invention, the following technical solution is adopted:

[0007] A large-particle-size crack-resistant cement stabilizer, comprising cement, TBM excavation material, fine aggregate, coarse aggregate, polypropylene fiber, magnesium crack-resistant agent, and water; the cement dosage is 50–150 kg / m³. 3 The material consumption for TBM tunnel excavation is 1250-2500 kg / m³. 3 External fine aggregate 0-1250 kg / m³ 3 External coarse aggregate 0-1250 kg / m³ 3 Polypropylene fiber 0.05~0.10kg / m 3 The dosage of magnesium-based crack-resistant agent is 1.0–4.5 kg / m². 3 The water consumption is 30-150 kg / m³. 3 .

[0008] Preferably, the large-particle-size crack-resistant cement stabilizer uses high-magnesium road silicate cement with a strength grade of 32.5, an initial setting time greater than 3 hours, a final setting time greater than 6 hours and less than 10 hours, and a specific surface area not greater than 350 m². 2 / kg, 28-day drying shrinkage not greater than 0.10%, alkali content not greater than 0.6%, magnesium oxide content 3.5%–5.0%. Cement admixture is the ratio of cement mass to aggregate mass, cement admixture 3.0%–6.0%.

[0009] Preferably, the magnesium-based crack-resistant agent is 2% to 3% of the cement content.

[0010] Preferably, the polypropylene fiber is a plastic bag fiber product, with a length not exceeding 3cm, a tensile strength ≥600MPa, and an elastic modulus ≤400MPa. The polypropylene fiber content is 0.05% to 0.07% by volume.

[0011] Preferably, the excavated material from the TBM tunnel is obtained by tunneling with a tunneling machine, and its saturated compressive strength is not less than 80 MPa, particle size is not greater than 150 mm, and moisture content is not greater than 3%. The excavated material from the TBM tunnel is not further processed, but only screened and stored according to particle size groups, which are <5 mm, 5 mm to 20 mm, 20 mm to 40 mm, 40 mm to 80 mm, and 80 mm to 150 mm.

[0012] Preferably, the fine aggregate is made from parent rock with the same properties as TBM, processed by an engineering sand and gravel system, or produced from purchased sand and gravel; it is medium-coarse sand with a moisture content of no more than 5%.

[0013] Preferably, the coarse aggregate is obtained by processing parent rock with the same properties as TBM, processing it through an engineering sand and gravel system, or purchasing finished materials from sand and gravel production plants. Its particle size distribution is 5mm–20mm, 20mm–40mm, 40mm–80mm, or 80mm–150mm, with a moisture content not exceeding 3%.

[0014] The present invention also provides a preparation method for preparing the large-particle-size crack-resistant cement stabilizer, comprising the following steps:

[0015] Determine the proportion of coarse aggregate in the cement stabilizer mix design. To determine the optimal proportions of coarse aggregates of 5mm–20mm, 20mm–40mm, 40mm–80mm, and 80mm–150mm in the cement stabilizer, and to provide a basis for selecting the proportion of coarse aggregate in the cement stabilizer mix design, a vibration compaction density test of the coarse aggregate composite gradation was conducted according to the "Highway Aggregate Test Procedure" JTGE42-2005. The maximum density value is the optimal proportion of coarse aggregate.

[0016] Determine the sand ratio. According to the determined optimal ratio of coarse aggregate, add different proportions of fine aggregate and mix them evenly. Conduct a natural bulk density test, and the maximum density is the optimal sand ratio.

[0017] Determine the maximum dry density and optimum moisture content. Air-dry the test aggregates and, according to the determined coarse aggregate ratio and optimum sand ratio, add different dosages of cement and different amounts of water to process the cement stabilized material in a plant. The required amount of water to be added for different dosages is calculated according to the "Test Procedure for Inorganic Binder Stabilized Materials in Highway Engineering" JTGE51-2009. Then, conduct maximum compaction tests on the plant-mixed cement stabilized materials for each cement dosage and different water additions on selected road sections. The paving thickness is the design thickness of the base or subbase layer, and the number of compaction passes is determined by the absence of change in settlement after the last five passes. Test the density of the cement stabilized material that has reached the maximum compaction state using the water-irrigation method according to the "Field Testing Procedure for Highway Subgrade and Pavement" JTG3430-2020. At least six sets of density tests should be conducted under the same cement dosage and water addition conditions. The maximum and minimum values ​​should be removed, and the average of the remaining four sets should be taken as the maximum dry density under that condition. The maximum dry density measured under the same cement dosage but different water addition is the maximum dry density and optimum moisture content of the cement stabilizer under that cement dosage.

[0018] Cure of cement-stabilized material in the compaction test section. Immediately after the density test, cover the cement-stabilized material in the compaction test section with two layers of geotextile and water it for curing. The curing period is 7 days, during which the frequency of watering should be maintained, ensuring the geotextile remains constantly moist.

[0019] Strength testing of cement-stabilized material core samples from the compacted test section. After 7 days of curing, core samples were drilled from the cement-stabilized material in the compacted test section. After indoor cutting and processing, the compressive strength of the core samples was tested. At least six sets of core samples were drilled under the same cement dosage and water addition conditions. The maximum and minimum values ​​were removed, and the average of the remaining four sets was taken as the compressive strength value of the core sample under those conditions.

[0020] Determine the cement content of the cement stabilizer. The minimum cement dosage is determined by using the core sample strength of the cement stabilizer in the compaction test section to achieve the design requirement of 7-day unconfined compressive strength.

[0021] Determine the mix proportion of cement stabilizer: The proportion of coarse and fine aggregates, cement content and water content determined in the above steps are the mix proportion of large particle size crack-resistant cement stabilizer.

[0022] According to a determined mix proportion for large-particle-size crack-resistant cement stabilizer, cement, TBM excavation material, fine aggregate admixture, coarse aggregate admixture, polypropylene fiber, magnesium crack-resistant agent, and water are weighed out respectively. The TBM excavation material, fine aggregate admixture, and coarse aggregate admixture are poured into a mixing tank and stirred evenly. Then, cement, polyacrylonitrile fiber, and magnesium crack-resistant agent are poured into the mixing tank and stirred evenly. Finally, water is added during the stirring process and stirring is continued until the mixture is fully stirred and homogeneous to obtain large-particle-size crack-resistant cement stabilizer.

[0023] This invention also provides a method for applying large-particle-size crack-resistant cement stabilized material, which is used in the construction of highway base or subbase. The cement stabilized material is laid according to the designed thickness of the base or subbase. Vibratory compaction is performed using the vibratory compaction equipment selected for the test section, with the number of compaction passes determined to achieve the designed compaction degree. Two layers of geotextile are used to fully cover the compacted cement stabilized material base or subbase, which has passed the compaction degree test, and water is sprayed for curing. During the curing period, the geotextile is kept constantly moist. After 7 days, core samples are drilled for strength testing and deflection testing.

[0024] The beneficial effects of this invention are:

[0025] This invention utilizes TBM excavated material through grading and screening without further processing. Addressing the discontinuous gradation, it employs the external addition of fine and coarse aggregates, effectively and rationally utilizing the excavated material. This avoids the land occupation associated with TBM excavated material stockpiling, improves the economic efficiency of the project, and protects the ecological environment.

[0026] This invention addresses the issue of coarse aggregate gradation and large particle size in TBM excavation materials, as well as the situation where the gradation range of inorganic binders exceeds the standard. By employing indoor combined gradation vibration density test and natural bulk density test to determine the aggregate combination ratio, a dense skeleton-type water-stabilized structure is formed, which can effectively reduce cracks caused by drying shrinkage and thermal shrinkage of water-stabilized materials.

[0027] This invention addresses the issue of coarse gradation and large particle size in TBM tunnel excavation materials, which mismatches the maximum particle size limit of indoor compaction testing instruments, making it impossible to directly obtain the maximum dry density and optimal moisture content through compaction tests. Alternatively, it addresses the problem of using gradation treatment followed by compaction tests, which fails to accurately reflect the actual compaction quality of the fill material. This invention utilizes a comprehensive method, including on-site rolling tests of plant-mixed materials and core drilling to determine the mix proportion of cement stabilized materials. This avoids the need to discard some TBM tunnel excavation materials or perform further processing on them due to maximum particle size limitations, thus saving costs and resulting in significant economic benefits.

[0028] This invention addresses the quality problem of cracking in water-stabilized layers of highway base or subbase courses. Firstly, it uses road silicate cement with a lower strength grade and limits its specific surface area, alkali content, and 28-day drying shrinkage rate to reduce the probability of cracking. Secondly, by increasing the magnesium oxide content in the cement, it fully utilizes the later-stage expansion of magnesium oxide to compensate for the cracking caused by the superposition of autogenous volume shrinkage and temperature drop in the cement stabilizer. Thirdly, by adding a magnesium-based crack-resistant agent and polypropylene fibers to the cement stabilizer, it further reduces the occurrence of cracks in the base or subbase water-stabilized layer. The magnesium-based crack-resistant agent contains highly active light-burned magnesium oxide, which expands relatively quickly at room temperature, further compensating for the autogenous volume shrinkage of the water stabilizer. The polypropylene fiber material has certain elasticity and tensile properties, which to some extent inhibits the possibility of large drying shrinkage deformation of the water-stabilized crushed stone, effectively enhancing the compressive strength and splitting tensile strength of the cement-stabilized crushed stone. In addition, the maximum dry density of the stabilized material was determined by on-site compaction tests, rather than by compaction tests after gradation treatment. This made the test results closer to reality, ensuring the compaction quality of the cement stabilized material during construction, preventing cracks in the water-stabilized material due to reduced compaction quality standards, and improving the quality of project construction.

[0029] The preparation method of this invention is simple and easy to operate, suitable for large-scale production, has important application value, and greatly improves the social and economic benefits of engineering. Attached Figure Description

[0030] Figure 1 This diagram illustrates the preparation and application of the large-particle-size crack-resistant cement stabilizer of this invention. The steps include: 1-Raw material testing; 2-Indoor aggregate gradation vibration density test and natural bulk density test; 3-Plant mixing and on-site compaction tests of stabilizers with different cement dosages and water additions; 4-Determining the cement stabilizer mix proportion; 5-Cement stabilizer preparation and processing; 6-Cement stabilizer paving and compaction construction; 7-Cement stabilizer construction quality inspection. Detailed Implementation

[0031] To enable those skilled in the art to more clearly understand the purpose, technical solution and advantages of the present invention, the present invention will be further described below in conjunction with the accompanying drawings and embodiments, but the present invention is not limited to the following embodiments.

[0032] In the description of this invention, unless otherwise expressly specified and limited, the terms should be interpreted broadly, and those skilled in the art can understand the specific meaning of each term in this invention according to the specific circumstances.

[0033] This invention provides a large-particle-size, crack-resistant cementitious stabilizer, comprising cement, TBM excavation material, fine aggregate admixture, coarse aggregate admixture, polypropylene fiber, magnesium-based crack-resistant agent, and water. The cement dosage is 50–150 kg / m³. 3 The material consumption for TBM tunnel excavation is 1250-2500 kg / m³. 3 External fine aggregate 0-1250 kg / m³ 3 External coarse aggregate 0-1250 kg / m³ 3 Polypropylene fiber 0.05~0.10kg / m 3 The dosage of magnesium-based crack-resistant agent is 1.0–4.5 kg / m². 3 Water consumption is 30-150 kg / m³ 3 .

[0034] In this invention, the cement used is high-magnesium road silicate cement with a strength grade of 32.5, an initial setting time greater than 3 hours, a final setting time greater than 6 hours and less than 10 hours, and a specific surface area not greater than 350 m². 2 / kg, 28-day shrinkage rate not greater than 0.10%, alkali content not greater than 0.6%, magnesium oxide content 3.5% to 5.0%.

[0035] The performance of the cement was tested according to the relevant test procedures. The test results are shown in Table 1. The cement quality meets the standard requirements of "Road Silicate Cement" (GB13693-2005) and the requirements of this invention for setting time, specific surface area, alkali content and magnesium oxide content.

[0036] Table 1 Test results of physical and mechanical properties of cement

[0037]

[0038] In this invention, the quality of the TBM excavation material, the fine aggregate admixture, and the coarse aggregate admixture are tested according to the "Specifications for Testing Aggregates in Highway Engineering" (JTGE42-2005). The test results are shown in Tables 2 to 5. Their quality meets the standard requirements in the "Technical Specifications for Construction of Highway Pavement Base Course" (JTG / TF20-2015) and the requirements of this invention for saturated compressive strength.

[0039] Table 2. Quality Inspection Results of Coarse Aggregate from TBM Excavation Material

[0040]

[0041] Table 3: Quality Inspection Results of Fine Aggregate from TBM Excavation Material

[0042]

[0043] Table 4 Quality Inspection Results of Coarse Aggregates Added Externally

[0044]

[0045] Table 5 Quality Inspection Results of Externally Added Fine Aggregates

[0046]

[0047]

[0048] The method for preparing the large-particle-size crack-resistant cement stabilizer of the present invention includes the following steps:

[0049] The proportion of coarse aggregate in the cement stabilizer mix design was determined. To determine the optimal proportions of coarse aggregates in the cement stabilizer at sizes of 5mm–20mm, 20mm–40mm, 40mm–80mm, and 80mm–150mm, and to provide a basis for selecting the coarse aggregate proportion in the cement stabilizer mix design, vibration-damped density tests of the coarse aggregate gradation were conducted according to the "Specifications for Highway Aggregate Testing" JTGE42-2005. The maximum density value was taken as the optimal proportion of coarse aggregate. The vibration-damped density tests of the aggregate gradation are shown in Table 6. The optimal proportions of coarse aggregates at sizes of 5mm–20mm, 20mm–40mm, 40mm–80mm, and 80mm–150mm were found to be 25:30:25:20.

[0050] Table 6 Results of compacted density test for aggregate gradation

[0051]

[0052] Determine the sand ratio. Based on the determined optimal proportion of coarse aggregate, add different proportions of fine aggregate and mix thoroughly. Conduct natural bulk density tests; the maximum density value is the optimal sand ratio. The optimal sand ratio natural bulk density tests are shown in Table 7. The optimal sand ratio was found to be 34%.

[0053] Table 7 Results of the test on the optimal sand ratio and natural bulk density

[0054]

[0055] Determine the maximum dry density and optimum moisture content. Air-dry the test aggregates and, according to the determined coarse aggregate ratio and optimum sand ratio, add different dosages of cement and different amounts of water to process the cement stabilized material in a plant. The required water mass for different water additions is calculated according to the "Test Procedure for Inorganic Binder Stabilized Materials in Highway Engineering" JTGE51-2009. Then, on selected road sections, conduct maximum compaction tests on the plant-mixed cement stabilized materials for each cement dosage and different water additions. The paving thickness is the design thickness of the base or subbase layer. The number of compaction passes is determined by the absence of change in settlement after the last five passes. The density of the cement stabilized material reaching the maximum compaction state is tested according to the water-filling density test in the "Field Testing Procedure for Highway Subgrade and Pavement" JTG3430-2020. At least six sets of density tests are conducted under the same cement dosage and water addition conditions. The maximum and minimum values ​​are removed, and the average of the remaining four sets is taken as the maximum dry density under that condition. The maximum dry density measured under the same cement dosage but different water addition is the maximum dry density and optimum moisture content of the cement stabilizer under that cement dosage.

[0056] Cure of cement-stabilized material in the compaction test section. After the density test is completed, immediately cover the cement-stabilized material in the test section with two layers of geotextile and water it for curing. The curing period is 7 days, and the frequency of watering should be maintained to keep the geotextile constantly moist.

[0057] Strength testing of cement-stabilized material core samples in the compaction test section. After curing the cement-stabilized material in the test section for 7 days, core samples were drilled and processed indoors for compressive strength testing. At least six sets of core samples were drilled under the same cement dosage and water addition conditions. The maximum and minimum values ​​were removed, and the average value of the remaining four sets was taken as the compressive strength value of the core sample under that condition.

[0058] Determine the cement content of the cement stabilizer. The minimum cement dosage is determined by using the core sample strength of the cement stabilizer in the compaction test section to achieve the design requirement of 7-day unconfined compressive strength.

[0059] Determine the mix proportion of cement stabilizer: The proportion of coarse and fine aggregates, cement content and water content determined in the above steps are the mix proportion of large particle size crack-resistant cement stabilizer.

[0060] The results of the maximum compaction test of the rolling test section are shown in Table 8.

[0061] Table 8. Results of Field Compaction Tests on Cement Stabilized Asphalt

[0062]

[0063]

[0064] Based on the analysis of the test results of the compaction section, in order to meet the design requirement that the 7-day unconfined compressive strength should be ≥3.5MPa, the optimal mix proportion of cement stabilizer was selected with a cement content of 3.5% and a water content of 5.5%. The mix proportion of cement stabilizer is shown in Table 9 below.

[0065] The cement stabilizer mix proportions determined in Table 9

[0066]

[0067] According to a determined mix proportion for large-particle-size crack-resistant cement stabilizer, cement, TBM excavation material, fine aggregate admixture, coarse aggregate admixture, polypropylene fiber, magnesium crack-resistant agent, and water are weighed out respectively. The TBM excavation material, fine aggregate admixture, and coarse aggregate admixture are poured into a mixing tank and stirred for 30 seconds. Then, cement, polyacrylonitrile fiber, and magnesium crack-resistant agent are poured into the mixing tank and stirred for 30 seconds. Finally, water is added during the stirring process and stirring is continued for 60 seconds. After thorough mixing, large-particle-size crack-resistant cement stabilizer is prepared.

[0068] Example and comparative examples of paving construction quality testing and inspection:

[0069] Example: Water-stabilized material was prepared according to the mix proportion and preparation method of large particle size crack-resistant cement stabilizer determined in Table 9 and then used for paving construction; Comparative example: Water-stabilized material produced using current conventional technology was used for on-site paving construction.

[0070] By testing and inspecting the 7-day unconfined compressive strength and crack condition of the examples and comparative examples, it was found that the 7-day unconfined compressive strength of the examples was higher than that of the comparative examples, but the examples had significantly fewer cracks than the comparative examples, and the examples had no transverse through cracks. The specific test and inspection results are shown in Table 10.

[0071]

[0072]

[0073] The application method of the large-particle-size crack-resistant cement stabilized material of the present invention is as follows: The large-particle-size crack-resistant cement stabilized material is used for the construction of highway base or subbase. The cement stabilized material is laid according to the thickness of the base or subbase as required by the design. Vibratory compaction is carried out using the vibratory compaction equipment selected according to the compaction test. The number of compaction passes is based on achieving the compaction degree required by the design. The cement stabilized material base or subbase that has been compacted and passed the compaction degree test is fully covered with two layers of geotextile and watered for curing. During the curing period, the geotextile is kept moist at all times. Core samples are drilled after 7 days for strength testing.

[0074] The above description is merely a preferred embodiment of the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A large-particle-size, crack-resistant cement stabilizer, characterized in that: The cement stabilizer is used in the base or subbase of highways. The cement stabilizer includes cement, TBM excavation material, fine aggregate, coarse aggregate, polypropylene fiber, magnesium-based crack-resistant agent, and water; the cement dosage is 50–150 kg / m³. 3 The material consumption for TBM tunnel excavation is 1250–2500 kg / m³. 3 External fine aggregate 0-1250 kg / m³, external coarse aggregate 0-1250 kg / m³ 3 The water consumption is 30–150 kg / m³. 3 ; The cement used is high-magnesium road silicate cement with a strength grade of 32.5, an initial setting time greater than 3 hours, a final setting time greater than 6 hours and less than 10 hours, and a specific surface area not exceeding 350 m². 2 / kg, 28-day drying shrinkage not greater than 0.10%, alkali content not greater than 0.6%, magnesium oxide content 3.5%–5.0%; cement admixture is the ratio of cement mass to aggregate mass, cement admixture 3.0%–6.0%; The magnesium-based crack-resistant agent is 2% to 3% of the cement content; In the cement stabilizer used in the base or subbase of highways, the polypropylene fiber is made of plastic bag fiber, with a length not exceeding 3cm, tensile strength ≥600MPa, elastic modulus ≤400MPa, and polypropylene fiber content of 0.05% to 0.07% by volume. The excavated material from the TBM tunnel is obtained by tunneling, and its saturated compressive strength is not less than 80MPa, the particle size is not greater than 150mm, and the moisture content is not greater than 3%. The excavated material from the TBM tunnel is not further processed, but only screened and stored according to particle size groups, which are <5mm, 5mm~20mm, 20mm~40mm, 40mm~80mm, and 80mm~150mm. When determining the proportion of coarse aggregate in the mix design of cement stabilizer, in order to determine the optimal proportion of coarse aggregates of 5mm-20mm, 20mm-40mm, 40mm-80mm, and 80mm-150mm in the cement stabilizer, and to provide a basis for the selection of the coarse aggregate proportion in the mix design of cement stabilizer, the compacted density test of the coarse aggregate combination gradation is carried out according to the "Highway Aggregate Test Procedure" JTGE42-2005. The maximum density is the optimal proportion of coarse aggregate. Under the determined coarse aggregate proportion, different proportions of fine aggregate are added and mixed evenly, and the natural bulk density test is carried out. The maximum density is the optimal sand ratio. To determine the maximum dry density and optimum moisture content, the test aggregates were air-dried. Based on the determined coarse aggregate ratio and optimum sand ratio, different dosages of cement and different amounts of water were added to produce cement stabilized aggregates. Then, on selected road sections, maximum compaction tests were conducted on the cement stabilized aggregates produced by the plant mixing process for each cement dosage and with different amounts of water. The paving thickness was the design thickness of the base or subbase layer. The number of compaction passes was determined by ensuring no change in settlement after the last five passes. The density of the cement stabilized aggregates reaching the maximum compaction state was tested using the water-irrigation density test method in the "Highway Subgrade and Pavement Field Testing Specifications" JTG3430-2020. At least six sets of density tests were conducted under the same cement dosage and water content conditions. The maximum and minimum values ​​were removed, and the average of the remaining four sets was taken as the maximum dry density value under that condition. The maximum dry density measured under the same cement dosage and different amounts of water is the maximum dry density and optimum moisture content of the cement stabilized aggregate at that cement dosage.

2. The large-particle-size crack-resistant cement stabilizer as described in claim 1, characterized in that: The fine aggregates are made from parent rock with the same properties as TBM, or from engineering sand and gravel systems, or from finished products purchased from sand and gravel plants; they are medium-coarse sand with a moisture content of no more than 5%.

3. The large-particle-size crack-resistant cement stabilizer as described in claim 1, characterized in that: The coarse aggregate is made from parent rock with the same properties as TBM, or from engineering sand and gravel systems, or from finished products purchased from sand and gravel production plants; its particle size is 5mm~20mm, 20mm~40mm, 40mm~80mm, 80mm~150mm, and its moisture content is not greater than 3%.

4. A preparation method for preparing the cement stabilizer as described in any one of claims 1 to 3, applicable to the base or subbase of a highway, characterized in that, Includes the following steps: To determine the optimal proportion of coarse aggregate in the cement stabilizer mix design, and to provide a basis for selecting the proportion of coarse aggregate in cement stabilizer mix design, the compacted density test of coarse aggregate composite gradation was conducted according to the "Highway Aggregate Test Procedure" JTGE42-2005. The maximum density value is the optimal proportion of coarse aggregate. Determine the sand ratio; according to the determined optimal ratio of coarse aggregate, add different proportions of fine aggregate and mix evenly, conduct a natural bulk density test, and the maximum density is the optimal sand ratio. Determine the maximum dry density and optimum moisture content; air-dry the test aggregates, and mix different dosages of cement and different amounts of water according to the determined coarse aggregate ratio and optimum sand ratio to produce cement stabilized materials; then conduct maximum compaction tests on the cement stabilized materials of each cement dosage and different amounts of water in selected road sections, with the paving thickness being the design thickness of the base or subbase, and the number of compaction passes being until the settlement remains unchanged after the last five passes to reach the densest state; test the density of the cement stabilized materials that have reached the densest state using the water-irrigation density test method in the "Specifications for Field Testing of Highway Subgrade and Pavement" JTG3430-2020; conduct at least six sets of density tests under the same cement dosage and water content conditions, remove the maximum and minimum values, and take the average of the other four sets as the maximum dry density value under that condition; the maximum dry density measured under the same cement dosage and different amounts of water is the maximum dry density and optimum moisture content of the cement stabilized material under that cement dosage. Cure of cement stabilized material in the compaction test section: After the density test is completed, immediately cover the cement stabilized material in the compaction test section with two layers of geotextile and water it for curing; the curing period is 7 days, and the frequency of watering should be ensured during this period, so that the geotextile is always kept moist. Strength testing of cement stabilized material core samples in the compaction test section; After 7 days of curing of cement stabilized material in the compaction test section, core samples were drilled and processed indoors, and the compressive strength of the core samples was tested; Under the same cement dosage and water addition conditions, at least six sets of core samples were drilled, the maximum and minimum values ​​were removed, and the average value of the other four sets was taken as the compressive strength value of the core sample under the conditions. Determine the cement content of the cement stabilizer; the minimum cement dosage is the cement content of the cement stabilizer, which is the minimum cement dosage required for the 7-day unconfined compressive strength of the cement stabilizer core sample in the compaction test section to reach the design requirement. Determine the mix proportion of cement stabilizer: The proportion of coarse and fine aggregates, cement content and water content determined in the above steps are the mix proportion of large particle size crack-resistant cement stabilizer.

5. A preparation method for preparing the cement-stabilized material for highway base or subbase as described in claim 4, characterized in that, Includes the following steps: According to the determined mix proportion of large-particle-size crack-resistant cement stabilizer, weigh out cement, TBM excavation material, fine aggregate, coarse aggregate, polypropylene fiber, magnesium crack-resistant agent and water respectively. Pour the TBM excavation material, fine aggregate and coarse aggregate into the mixing tank and stir evenly. Then pour the cement, polypropylene fiber and magnesium crack-resistant agent into the mixing tank and stir evenly. Finally, add water during the stirring process and continue stirring evenly. After thorough mixing, the large-particle-size crack-resistant cement stabilizer is made.

6. A method for applying the large-particle-size crack-resistant cement stabilizer as described in any one of claims 1 to 3, characterized in that: The large-particle-size crack-resistant cement stabilized material is used for the construction of highway base or subbase. The cement stabilized material is laid according to the thickness of the base or subbase as required by the design. Vibratory compaction is carried out according to the vibratory compaction equipment selected in the compaction test section. The number of compaction passes is based on achieving the compaction degree required by the design. The cement stabilized material base or subbase that has been compacted and passed the compaction degree test is fully covered with two layers of geotextile and watered for curing. During the curing period, the geotextile is kept moist. After 7 days, core samples are drilled for strength testing and deflection testing.

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