Bone-dense micro-pore closed cement stabilized slag material, preparation method and application thereof

Abstract

The application provides a bone dense micro-pore closed cement stabilized construction waste material and a preparation method and application thereof, and the material comprises the following components in parts by mass: 84-88 parts of construction waste recycled aggregate, 2-5 parts of cement, 2-4 parts of water-soluble silane coupling agent and 9-12 parts of water, wherein the construction waste recycled aggregate comprises brick and concrete construction waste or cement concrete construction waste. In the preparation, the construction waste recycled aggregate is first immersed in a silane coupling agent solution, then the cement is added into the construction waste recycled aggregate after sufficient soaking, and the mixture is uniformly mixed and compacted to obtain the bone dense micro-pore closed cement stabilized construction waste material. Compared with the prior art, the prepared granule has stronger performance, better material gradation and higher material strength, can better meet the service requirements of base materials such as airport pavements, and the material is prepared by using the construction waste with poor properties, is green and environmentally friendly, and has considerable social and economic benefits.

Description

Technical Field

[0001] This invention relates to the field of airport runway engineering technology, and in particular to a dense microporous sealed cement-stabilized construction waste material that can be mixed with different types of construction waste, its preparation method and application. Background Technology

[0002] With the rapid development of civil airport and infrastructure construction in my country, the development and use of building materials have accelerated resource consumption and environmental damage, leading to a continuous rise in the price of natural stone for infrastructure construction. Therefore, research on alternatives to natural aggregates is urgently needed.

[0003] During the construction of civil airports, various building and highway reconstruction and expansion projects generate a large amount of solid construction waste, commonly known as construction waste. Among these, brick-concrete and cement concrete construction waste are the most common and largest in the demolition and renovation projects of various low-grade civil buildings in towns and suburbs, but they also have the disadvantages of poor material properties and difficulty in reuse.

[0004] In recent years, the two types of construction waste mentioned above have begun to be used in the subbase of low-grade roads and even expressways. However, for water-stabilized base courses, it is difficult to meet the strength requirements of the base material through simple cement treatment. For airport runways, due to the large dynamic loads from aircraft takeoffs and landings, the pavement's own weight, and the long design life, the requirements for base materials are high, mainly in terms of strength and durability. Precisely because of the high safety requirements for airport runways, there are currently no relevant cases of using construction waste in the design of runway base materials.

[0005] In view of this, it is necessary to design a cement-stabilized construction waste material and its preparation method that can fully reuse construction waste generated during demolition and renovation, distinguish different types of construction waste, and be specifically applied to the base layer of the roadway, in order to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a dense microporous sealed cement-stabilized slag material that can be applied to the base course of civil airports and high-grade highways, as well as its preparation method and application.

[0007] The objective of this invention can be achieved through the following technical solutions:

[0008] One aspect of the present invention is to provide a skeleton-dense (i.e., dense-skeleton) microporous sealed cement-stabilized construction waste material, the material comprising the following components: recycled construction waste aggregate, cement, water-soluble silane coupling agent and water.

[0009] Furthermore, the material comprises the following components in parts by weight: 84-88 parts of recycled construction waste aggregate, 2-5 parts of cement, 2-4 parts of water-soluble silane coupling agent, and 9-12 parts of water.

[0010] Furthermore, the types of recycled construction waste aggregates include recycled aggregates from brick-concrete construction waste or recycled aggregates from cement concrete construction waste.

[0011] Furthermore, for the base materials of high-level airports, recycled aggregates from brick-concrete construction waste can be selected.

[0012] Furthermore, for the base material of high-grade airports, recycled aggregates from cement concrete construction waste can be selected.

[0013] Furthermore, the particle size of the recycled construction waste aggregate can include three ranges: 10-30mm, 5-10mm, and 0-5mm.

[0014] Furthermore, in the recycled aggregate of brick-concrete construction waste, the mass percentage of cement concrete blocks in the 10-30mm size range is greater than 35%, and the mass percentage of cement concrete blocks in the 5-10mm size range is greater than 25%.

[0015] Furthermore, in the recycled aggregate of brick-concrete construction waste, the amounts of 10-30mm, 5-10mm, and 0-5mm are 40.0%-55.0%, 0.0%-10.0%, and 40.0%-50.0% by mass, respectively.

[0016] Furthermore, in the recycled aggregates of cement concrete construction waste, the amounts of 10-30mm, 5-10mm, and 0-5mm are 40.0%-50.0%, 30.0%-40.0%, and 10.0%-20.0% by mass, respectively.

[0017] Furthermore, the key influencing sieve apertures for the synthetic gradation of the bone-dense microporous sealed cement-stabilized building slag material include 31.5mm, 19mm, 9.5mm, 4.75mm, 0.6mm, and 0.075mm, with corresponding passing percentage ranges of: 100%–100%, 70%–85%, 45%–60%, 25%–35%, 5%–15%, and 0%–3%.

[0018] Furthermore, the amount of cement used accounts for 2.0% to 6.0% of the mass of the recycled construction waste aggregate; the amount of water used accounts for 11.0% to 14.0% of the mass of the recycled construction waste aggregate.

[0019] Furthermore, the cement is P·O42.5 cement.

[0020] Another aspect of the present invention is to provide a method for preparing the aforementioned bone-dense microporous sealed cement-stabilized building slag material, the method comprising the following steps:

[0021] S1 involves recycling construction waste and then performing pre-treatment processes such as crushing, magnetic separation, air separation, and screening. Based on the type of original construction waste, recycled aggregates of brick-concrete construction waste or cement concrete construction waste are obtained and classified according to particle size.

[0022] S2, mix the recycled construction waste aggregates with particle sizes including 10-30mm, 5-10mm, and 0-5mm evenly according to the design ratio to obtain the basic raw materials;

[0023] S3. Mix water and ethanol solution in a volume ratio of 40:60 to 50:50 and stir evenly. Add water-soluble silane coupling agent and stir thoroughly to obtain a strengthening solution. Then immerse the base raw material in the strengthening solution for wetting and strengthening.

[0024] S4. Take out the impregnated and reinforced base material, dry it, add water to the base material minus 2% of the design water volume relative to the mass of the recycled construction waste aggregate, stir it thoroughly and let it stand for 1 hour.

[0025] S5, after being fully impregnated, adds the designed amount of cement and 2% water relative to the mass percentage of the recycled construction waste aggregate to the base raw materials, and mixes them thoroughly to obtain a dense microporous cement-stabilized construction waste material.

[0026] Furthermore, in step S3, the stirring time is 120-150 seconds and the strengthening time is 12-16 hours.

[0027] Furthermore, in step S4, the drying temperature is 70-80°C, the drying time is 6-9 hours, and the resting time is 6-10 hours.

[0028] Furthermore, in step S5, the mixing time is 90 to 120 seconds.

[0029] Furthermore, a single-shaft concrete mixer is used for mixing in steps S4 and S5; a concrete mixer can be used for mixing during large-scale construction.

[0030] Another aspect of the present invention is to provide an application of the above-mentioned dense microporous sealed cement-stabilized building slag material in the base course of airport runways and highway pavement structures.

[0031] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0032] 1) This invention uses a large amount of low-grade brick-concrete and cement concrete construction waste generated during demolition and renovation projects as basic raw materials, and mixes them evenly with cement, water-soluble silane coupling agent and water. At the same time, the proportion of each raw material is controlled to prepare a bone-dense microporous sealed cement-stabilized construction waste material.

[0033] 2) Specifically, this invention addresses the inherent porosity of recycled construction waste aggregates by strengthening them through immersion in a silane coupling agent solution. This seals the pores and enhances the particle strength. The specific principle is as follows: the silane coupling agent, chemically known as propyltrimethoxysilane, is water-soluble and undergoes a hydrolysis reaction to produce methanol. The ethanol-water solution environment allows the silane coupling agent to be more fully dispersed in the aqueous solution, resulting in a more stable hydrolysate. On one hand, after curing, the silane coupling agent uniformly coats the surface of the recycled construction waste aggregates with a thin film of outward-facing hydrophobic groups, reducing the surface energy and transforming the surface from hydrophilic to hydrophobic. Macroscopically, this results in a decrease in water absorption and apparent density in the recycled particles. On the other hand, the silane coupling agent shrinks during curing, generating additional stress on the aggregate surface and tightening the adhesive material at the interface, forming a restraint layer with decreasing modulus to uniformly transfer stress. Furthermore, it can bond particle cracks and fill open pores. Macroscopically, this results in a decrease in the crushing value of the recycled particles.

[0034] 3) In particular, this invention addresses the inherent poor properties of recycled construction waste aggregates by employing aggregate screening and grading, along with optimized design for a dense skeleton gradation. This allows large-diameter aggregates to fully utilize their skeleton interlocking effect, while small-diameter aggregates fully utilize their skeleton void-filling effect, resulting in a cement-stabilized construction waste material with low porosity and high density. This material exhibits advantages such as low permeability and good water stability. Because the interlocking of particles within the skeleton provides a certain strength, the overall material strength is higher than that of general gradation materials, while its performance is less affected by the strength of the cement mortar. Furthermore, the mixture gradation meets the recommended gradation range for water-stabilized crushed stone base courses in the current airport standard "Technical Specification for Construction of Earthwork and Pavement Subbase (Subbase) Layers in Civil Airport Flight Areas" (MH / T 5014-2022), satisfying engineering application requirements.

[0035] 4) The 7-day unconfined immersion compressive strength of the bone-dense microporous closed cement-stabilized brick-concrete building slag material obtained by the present invention reaches 3.0 to 3.5 MPa, which meets the requirements of the "Design Specification for Cement Concrete Pavement of Civil Airports" (MH / T 5004-2010) for the base course material of high-grade airport pavement, and is close to the performance index of cement-stabilized crushed stone base course materials commonly used in airfield engineering.

[0036] 5) The 7-day unconfined compressive strength of the bone-dense microporous closed cement-stabilized cement concrete-like building slag material obtained by this invention reaches 5.0-9.0 MPa, and the 7-day compressive resilient modulus reaches 750.0 MPa-920.0 MPa, which meets the requirements of the "Design Specification for Cement Concrete Pavement of Civil Airports" (MH / T5004-2010) for base course materials of high-grade airport pavement, and exceeds the performance indicators of cement-stabilized crushed stone base course materials commonly used in airfield engineering.

[0037] 6) The material involved in this invention utilizes the synergistic effect between various raw materials to prepare high-strength roadbed base material while effectively improving the recycling rate of construction waste. This not only effectively reduces the material cost of roadbed base material, but also facilitates the recycling of resources, conforms to the principle of resource utilization and harmless use of construction waste, and has good economic and environmental benefits.

[0038] 7) The base material of the runway provided by the present invention has a simple composition, a clear mixing ratio, and a simple preparation process. Moreover, the amount of each component can be adjusted according to the actual performance of the raw materials, which is easy to control and can meet the needs of large-scale on-site production and construction, and has high application value. Detailed Implementation

[0039] To make the objectives, features, and beneficial effects of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described below are merely illustrative of the present invention and not intended to limit the scope of the invention.

[0040] Example 1:

[0041] This embodiment provides a dense, microporous, sealed cement-stabilized building slag material and its preparation method. This dense, microporous, sealed cement-stabilized building slag material can be applied to the subbase of high-grade civil airports and the base course of high-grade highways.

[0042] This dense microporous sealed cement-stabilized building waste material comprises the following components by weight: 84 parts recycled aggregate from brick-concrete construction waste, 2 parts cement, 4 parts water-soluble silane coupling agent, and 9 parts water.

[0043] The mass ratio of the three grades of recycled aggregates from brick-concrete construction waste is as follows: 10-30mm, 5-10mm, 0-5mm = 52.7% : 1.9% : 45.4%.

[0044] The preparation method of this dense, microporous, sealed cement-stabilized building slag material is as follows:

[0045] S1 involves recycling construction waste and then performing pre-treatment processes such as crushing, magnetic separation, air separation, and screening. Based on the type of original construction waste, recycled aggregates of brick-concrete construction waste are obtained and classified into three grades according to particle size.

[0046] S2, mix the pre-treated three grades of recycled aggregate from brick-concrete construction waste evenly in proportion to obtain the basic raw materials;

[0047] S3, mix water and ethanol solution in a volume ratio of 40:60 and stir evenly, add the specified mass of silane coupling agent and stir thoroughly for 120 seconds to obtain the strengthening solution, and then immerse the base raw material in the strengthening solution for 12 hours.

[0048] S4. Take out the impregnated and strengthened base material, dry it at 70℃ for 6 hours, add water to the base material with the designed water volume minus 2% of the mass fraction of the recycled aggregate of brick and concrete construction waste, stir it thoroughly and let it stand for 8 hours.

[0049] S5, after being fully soaked, adds the designed amount of cement and 2% water (by mass fraction relative to the recycled aggregate of brick-concrete construction waste) to the base raw materials, mixes thoroughly for 90 seconds, and obtains the aggregate-dense microporous closed cement-stabilized construction waste material.

[0050] Example 2:

[0051] This embodiment provides a dense, microporous, sealed cement-stabilized building slag material and its preparation method. This dense, microporous, sealed cement-stabilized building slag material can be applied to the subbase of high-grade civil airports and the base course of high-grade highways.

[0052] This dense microporous sealed cement-stabilized building waste material comprises the following components by weight: 88 parts recycled aggregate from brick-concrete construction waste, 5 parts cement, 2 parts water-soluble silane coupling agent, and 12 parts water.

[0053] The mass ratio of the three grades of recycled aggregate in brick-concrete construction waste is as follows: 10-30mm, 5-10mm, 0-5mm = 50.6% : 3.5% : 45.9%.

[0054] The preparation method of this dense, microporous, sealed cement-stabilized building waste material is similar to that of Example 1. The difference lies in the following: In step S3, the volume ratio of water to ethanol solution is 50:50; the stirring time between the recycled aggregate from brick-concrete construction waste and the silane coupling agent is 150 seconds; and the immersion time of the base material in the strengthening solution is 16 hours. In step S4, the drying temperature of the base material is 80°C, and the drying time is 9 hours. In step S5, the thorough stirring time of the base material with cement and water is 120 seconds.

[0055] Example 3:

[0056] This embodiment provides a dense, microporous, sealed cement-stabilized building slag material and its preparation method. This dense, microporous, sealed cement-stabilized brick-concrete building slag material can be applied to the subbase of high-grade civil airports and the base course of high-grade highways.

[0057] This dense microporous sealed cement-stabilized building waste material comprises the following components by weight: 86 parts recycled aggregate from brick-concrete construction waste, 3 parts cement, 3 parts water-soluble silane coupling agent, and 10 parts water.

[0058] The mass ratio of the three grades of recycled aggregate in brick-concrete construction waste is as follows: 10-30mm, 5-10mm, 0-5mm = 49.8% : 5.5% : 44.7%.

[0059] The preparation method of this dense, microporous, sealed cement-stabilized building waste material is similar to that of Example 1. The difference lies in the following: In step S3, the ratio of water to ethanol solution is 45:45; the stirring time between the recycled aggregate from brick-concrete construction waste and the silane coupling agent is 130 seconds; and the immersion time of the base materials in the strengthening solution is 14 hours. In step S4, the drying temperature of the base materials is 75°C, and the drying time is 8 hours. In step S5, the thorough stirring time of the base materials with cement and water is 100 seconds.

[0060] Example 4:

[0061] This embodiment provides a dense, microporous, sealed cement-stabilized building slag material and its preparation method. This dense, microporous, sealed cement-stabilized building slag material can be applied to the subbase of high-grade civil airports and the base course of high-grade highways.

[0062] This dense microporous sealed cement-stabilized building waste material comprises the following components by weight: 84 parts recycled aggregate from brick-concrete construction waste, 3 parts cement, 4 parts water-soluble silane coupling agent, and 9 parts water.

[0063] The mass ratio of the three grades of recycled aggregates from brick-concrete construction waste is as follows: 10-30mm, 5-10mm, 0-5mm = 52.7% : 1.9% : 45.4%.

[0064] The preparation method of this bone-dense microporous sealed cement-stabilized slag material is the same as that of Example 1.

[0065] Example 5:

[0066] This embodiment provides a dense, microporous, sealed cement-stabilized building slag material and its preparation method. This dense, microporous, sealed cement-stabilized cement concrete-like building slag material can be applied to the upper base course of high-grade civil airports and the base course of high-grade highways.

[0067] This dense microporous sealed cement-stabilized construction waste material comprises the following components by weight: 84 parts recycled aggregate from cement concrete construction waste, 2 parts cement, 4 parts water-soluble silane coupling agent, and 9 parts water.

[0068] The mass ratio of the three grades of recycled aggregates from cement concrete construction waste is as follows: 10-30mm, 5-10mm, 0-5mm = 47.1% : 35.3% : 17.6%.

[0069] The preparation method of this bone-dense microporous sealed cement-stabilized slag material is the same as that of Example 1.

[0070] Example 6:

[0071] This embodiment provides a dense, microporous, sealed cement-stabilized building slag material and its preparation method. This dense, microporous, sealed cement-stabilized cement concrete-like building slag material can be applied to the upper base course of high-grade civil airports and the base course of high-grade highways.

[0072] This dense microporous sealed cement-stabilized construction waste material comprises the following components by weight: 88 parts recycled aggregate from cement concrete construction waste, 5 parts cement, 2 parts water-soluble silane coupling agent, and 12 parts water.

[0073] The mass ratio of the three grades of recycled aggregates from cement concrete construction waste is as follows: 10-30mm, 5-10mm, 0-5mm = 45.2% : 34.3% : 20.5%.

[0074] The preparation method of this dense microporous sealed cement-stabilized slag material is the same as that of Example 2.

[0075] Example 7:

[0076] This embodiment provides a dense, microporous, sealed cement-stabilized building slag material and its preparation method. This dense, microporous, sealed cement-stabilized cement concrete-like building slag material can be applied to the upper base course of high-grade civil airports and the base course of high-grade highways.

[0077] This dense microporous sealed cement-stabilized construction waste material comprises the following components by weight: 86 parts recycled aggregate from cement concrete construction waste, 3 parts cement, 3 parts water-soluble silane coupling agent, and 10 parts water.

[0078] The mass ratio of the three grades of recycled aggregates from cement concrete construction waste is as follows: 10-30mm, 5-10mm, 0-5mm = 44.5% : 36.1% : 19.4%.

[0079] The preparation method of this dense microporous sealed cement-stabilized slag material is the same as that in Example 3.

[0080] Example 8:

[0081] This embodiment provides a dense, microporous, sealed cement-stabilized building slag material and its preparation method. This dense, microporous, sealed cement-stabilized cement concrete-like building slag material can be applied to the upper base course of high-grade civil airports and the base course of high-grade highways.

[0082] This dense microporous sealed cement-stabilized construction waste material comprises the following components by weight: 84 parts recycled aggregate from cement concrete construction waste, 3 parts cement, 4 parts water-soluble silane coupling agent, and 9 parts water.

[0083] The mass ratio of the three grades of recycled aggregates from cement concrete construction waste is as follows: 10-30mm, 5-10mm, 0-5mm = 47.1% : 35.3% : 17.6%.

[0084] The preparation method of this bone-dense microporous sealed cement-stabilized slag material is the same as that of Example 1.

[0085] Comparative Example 1:

[0086] This comparative example provides a dense cement-stabilized building slag material.

[0087] This aggregate-dense cement-stabilized building waste material comprises the following components by weight: 84 parts recycled aggregate from brick-concrete construction waste, 2 parts cement, and 9 parts water.

[0088] The mass ratio of the three grades of recycled aggregates from brick-concrete construction waste is as follows: 10-30mm, 5-10mm, 0-5mm = 52.7% : 1.9% : 45.4%.

[0089] The preparation method of this dense cement-stabilized building slag material is as follows:

[0090] S1 involves recycling construction waste and then performing pre-treatment processes such as crushing, magnetic separation, air separation, and screening. Based on the type of original construction waste, recycled aggregates of brick-concrete construction waste are obtained and classified into three grades according to particle size.

[0091] S2, mix the pre-treated three-grade brick-concrete construction waste recycled aggregate evenly to obtain the basic raw material;

[0092] S3, add water that is 2% of the mass percentage of the recycled aggregate relative to the designed water volume, mix for 40 seconds, and let stand for 1 hour.

[0093] S4, add water at a mass fraction of 2% relative to the recycled aggregate of brick-concrete construction waste and the designed amount of cement, mix for 90 seconds to obtain the skeleton-dense cement-stabilized construction waste material.

[0094] Comparative Example 2:

[0095] This comparative example provides a dense cement-stabilized building slag material.

[0096] This aggregate-dense cement-stabilized building waste material comprises the following components by weight: 84 parts recycled aggregate from cement concrete construction waste, 2 parts cement, and 9 parts water.

[0097] The mass ratio of the three grades of recycled aggregates from cement concrete construction waste is as follows: 10-30mm, 5-10mm, 0-5mm = 47.1% : 35.3% : 17.6%.

[0098] The preparation method of this dense cement-stabilized slag material is the same as that of Comparative Example 1.

[0099] Comparative Example 3:

[0100] This comparative example provides a standard-graded cement-stabilized building slag material.

[0101] The standard graded cement-stabilized brick-concrete construction waste material includes the following components by weight: 84 parts recycled aggregate of brick-concrete construction waste, 3 parts cement, 4 parts water-soluble silane coupling agent, and 9 parts water.

[0102] The mass ratio of the three grades of recycled aggregate in brick-concrete construction waste is as follows: 10-30mm, 5-10mm, 0-5mm = 35.5%: 16.8%: 47.7%.

[0103] The preparation method of the graded cement stabilized slag material in this specification is the same as that in Comparative Example 1.

[0104] Comparative Example 4:

[0105] This comparative example provides a standard-graded cement-stabilized building slag material.

[0106] The graded cement stabilized cement concrete construction waste material of this specification includes the following components by weight: 84 parts recycled aggregate of cement concrete construction waste, 3 parts cement, 4 parts water-soluble silane coupling agent, and 9 parts water.

[0107] The mass ratio of the three grades of recycled aggregates from cement concrete construction waste is as follows: 10-30mm, 5-10mm, 0-5mm = 37.1%: 17.3%: 45.6%.

[0108] The preparation method of the graded cement stabilized slag material in this specification is the same as that in Comparative Example 1.

[0109] Comparative Example 5:

[0110] This comparative example provides a cement-stabilized natural crushed stone material commonly used in track systems.

[0111] The cement-stabilized natural crushed stone base material comprises the following components by weight: 84 parts natural crushed stone aggregate, 2 parts cement, and 9 parts water.

[0112] The natural crushed stone aggregate includes limestone crushed stone aggregate, and the mass ratio of the three grades of natural crushed stone aggregate is: 10~30mm, 5~10mm, 0~5mm = 37.5%: 16.7%: 45.8%, which meets the gradation requirements of the roadbed base material.

[0113] The preparation method of this cement-stabilized crushed stone base course material is as follows:

[0114] S1, mix the three grades of natural crushed stone aggregate evenly;

[0115] S2, add water that is 2% of the mass fraction of the natural crushed stone aggregate minus the designed water volume, mix for 40 seconds, and let stand for 4 hours;

[0116] S3, add water at a mass fraction of 2% relative to the natural crushed stone aggregate and the designed amount of cement, mix for 60 seconds to obtain the cement-stabilized crushed stone base material.

[0117] Comparative Example 6:

[0118] This comparative example provides a cement-stabilized natural crushed stone material commonly used in track systems.

[0119] The cement-stabilized natural crushed stone base material comprises the following components by weight: 84 parts natural crushed stone aggregate, 3 parts cement, and 9 parts water.

[0120] The natural crushed stone aggregate includes limestone crushed stone aggregate, and the mass ratio of the three grades of natural crushed stone aggregate is: 10~30mm, 5~10mm, 0~5mm = 37.5%: 16.7%: 45.8%, which meets the gradation requirements of the roadbed base material.

[0121] The preparation method of this cement-stabilized crushed stone base material is the same as that of Comparative Example 5.

[0122] In this invention, the performance tests of each embodiment and comparative example are as follows:

[0123] 7-day unconfined compressive strength:

[0124] Refer to the "Test Procedures for Inorganic Binder Stabilized Materials in Highway Engineering" JTG E51-2009 T0805

[0125] 7-day compressive resilience modulus:

[0126] Refer to the "Test Procedures for Inorganic Binder Stabilized Materials in Highway Engineering" JTG E51-2009 T0808

[0127] 7-day splitting strength:

[0128] Refer to the "Test Procedures for Inorganic Binder Stabilized Materials in Highway Engineering" JTG E51-2009 T0806

[0129] Performance comparison:

[0130] Table 1. Material Proportioning for Runway Base Layer

[0131]

[0132] Table 2. Comprehensive Performance Test Results of Roadbed Materials

[0133]

[0134] As shown in Table 2, the addition of cement and silane coupling agent in Examples 1, 2, and 3 significantly improves the strength indicators of the dense-skeletal brick-concrete construction waste, and meets the 3MPa compressive strength requirement for airport pavement subbase materials in the "Design Code for Cement Concrete Pavement of Civil Airports" (MH / T5004-2010). Therefore, the dense-skeletal cement-stabilized brick-concrete construction waste recycled aggregate provided by this invention meets the application requirements for high-grade airport pavement subbase materials.

[0135] Analysis of Examples 5, 6, and 7 in Table 2 shows that the addition of cement and silane coupling agent significantly improves the strength indicators of the skeleton-dense cement concrete-type construction waste, and meets the 4MPa compressive strength requirement for base course materials on airport pavements as stipulated in the "Design Code for Cement Concrete Pavements of Civil Airports" (MH / T 5004-2010). Therefore, the skeleton-dense cement-stabilized cement concrete-type recycled aggregate from construction waste provided by this invention meets the application requirements for base course materials on high-grade airport pavements.

[0136] As shown in Table 1, the difference between Example 1 and Comparative Example 1, and between Example 5 and Comparative Example 2, lies in whether a water-soluble silane coupling agent is incorporated into the cement-stabilized construction waste material. After incorporating the silane coupling agent, the 7-day unconfined compressive strength of Examples 1 and 5 reached 3.25 MPa and 5.36 MPa, respectively, while the 7-day unconfined compressive strength of Comparative Examples 1 and 2 was only 2.41 MPa and 2.59 MPa. This indicates that the addition of the water-soluble silane coupling agent significantly improves the various strength and mechanical properties of the cement-stabilized construction waste material, demonstrating a good strengthening effect on material performance. Furthermore, materials without the water-soluble silane coupling agent cannot meet the material requirements for the subbase of airport runways. This difference is related to the strengthening effect of the silane coupling agent on the recycled construction waste aggregate. On one hand, after curing, the silane coupling agent can uniformly cover the surface of the recycled construction waste aggregate with a thin film of outward-facing hydrophobic groups, reducing the surface energy of the recycled aggregate and thus changing the surface from hydrophilic to hydrophobic. The macroscopic manifestations of recycled aggregates are a decrease in water absorption and apparent density. On the other hand, the silane coupling agent shrinks during curing, generating additional stress on the aggregate surface and tightening the adhesive material at the interface, forming a restraint layer with decreasing modulus to uniformly transfer stress. Furthermore, it can bond aggregate cracks and fill open pores. Therefore, the macroscopic manifestation of recycled aggregates shows a certain degree of decrease in crushing value.

[0137] As shown in Table 1, the difference between Example 4 and Comparative Example 3, and between Example 8 and Comparative Example 4, lies in whether the cement-stabilized construction waste material uses a dense-skeletal gradation. With the dense-skeletal gradation, the 7-day unconfined compressive strength of Examples 4 and 8 reached 3.71 MPa and 6.48 MPa, respectively, while the 7-day unconfined compressive strength of Comparative Examples 3 and 4 were only 2.12 MPa and 2.39 MPa. This indicates that a dense-skeletal gradation is beneficial for achieving higher strength in cement-stabilized construction waste material. This is mainly because the recycled aggregates from construction waste have poor inherent properties. Through aggregate screening and grading, and optimized design with a dense-skeletal gradation, large-diameter aggregates fully utilize the skeleton interlocking effect, while small-diameter aggregates fully utilize the skeleton void-filling effect, resulting in a cement-stabilized construction waste material with low porosity and high density, exhibiting advantages such as low permeability and good water stability. Because the interlocking of particles between the skeleton provides a certain strength, the overall material strength is higher than that of general gradation materials, and its performance is less affected by the strength of the cement mortar.

[0138] As shown in Table 1, the main difference between Example 1 and Example 4, Example 5 and Example 8, and Comparative Example 5 and Comparative Example 6 is that the cement content is 2 or 3 parts. For aggregate-dense microporous cement-stabilized brick-concrete slag, increasing the cement content by 1 part increases the 7-day unconfined compressive strength of the mixture from 3.25 MPa to 3.71 MPa, an increase of 14%. For aggregate-dense microporous cement-stabilized cement concrete slag, increasing the cement content by 1 part increases the 7-day unconfined compressive strength of the mixture from 5.36 MPa to 6.48 MPa, an increase of 21%. For cement-stabilized natural crushed stone, increasing the cement content by 1 part increases the 7-day unconfined compressive strength of the mixture from 4.92 MPa to 6.15 MPa, an increase of 25%. Therefore, aggregate-dense microporous cement-stabilized slag is more sensitive to the cement content than cement-stabilized natural crushed stone. Specifically, dense-textured microporous cement-stabilized brick-concrete slag is less sensitive to cement content than dense-textured microporous cement-stabilized cement concrete slag. This is mainly because the surface of brick-concrete slag is rougher and has more open pores than that of cement concrete slag. Although the micropores on the slag surface are sealed with silane coupling agents, the specific surface area of ​​brick-concrete slag is still larger than that of cement concrete slag. Under the same degree of cement coating, the former requires more cement than the latter, and there is less cement paste left to provide the strength of the mixture. Therefore, brick-concrete slag is slightly less sensitive to cement content.

[0139] As shown in Table 1, the main difference between Examples 4 and 8 and Comparative Example 6 is whether the mixture material is a dense, microporous, closed-cell cement-stabilized building slag. Under the same mix proportion, for the dense, microporous, closed-cell cement-stabilized building slag, the 7-day unconfined compressive strength of Examples 4 and 8 reached 3.71 MPa and 6.48 MPa, respectively; for the cement-stabilized natural crushed stone base material, it was 6.15 MPa. Therefore, the workability of dense, microporous, closed-cell cement-stabilized brick-concrete building slag is worse than that of ordinary cement-stabilized crushed stone, while the workability of dense, microporous, closed-cell cement-stabilized cement concrete building slag is even better than that of ordinary cement-stabilized crushed stone.

[0140] Therefore, the aggregate-dense microporous sealed cement-stabilized slag material provided by this invention can be used in the base course of airport runways. The performance of this aggregate-dense microporous sealed cement-stabilized cement concrete slag material is even superior to that of ordinary cement-stabilized crushed stone base course materials, meeting the application requirements for base course materials in high-grade airport runways.

[0141] The results show that the cementitious materials, void-sealing materials, and dense-graded aggregate design used in this invention effectively improve the strength of water-stabilized construction waste materials, meeting the strength requirements of airport pavement base materials. Furthermore, the type of construction waste, the amount of sealant, and the amount of cement can be adjusted according to the application scenario of different pavement base layers, allowing for targeted control. Simultaneously, the raw materials used in this invention are cheaper and easier to obtain than conventional materials, thus saving on raw material costs for engineering projects. More importantly, the application of this invention will solve the problem of reusing low-grade construction waste materials, resulting in environmental benefits far exceeding its economic benefits.

[0142] Although specific embodiments have been described above, these embodiments are not intended to limit the scope of the invention, even when only a single embodiment is described with respect to a particular feature. The feature examples provided in this disclosure are intended to be illustrative and not limiting, unless otherwise stated. In practice, one or more technical features of the dependent claims may be combined with the technical features of the independent claims as needed and where technically feasible, and the technical features from the respective independent claims may be combined in any suitable manner rather than solely by the specific combinations listed in the claims.

[0143] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A bone-dense, microporous, sealed cement-stabilized building slag material, characterized in that, The composition includes the following components by weight: 84-88 parts of recycled construction waste aggregate, 2-5 parts of cement, 2-4 parts of water-soluble silane coupling agent, and 9-12 parts of water; The water-soluble silane coupling agent is propyltrimethoxysilane; The recycled aggregate from construction waste includes recycled aggregate from brick-concrete construction waste or recycled aggregate from cement-concrete construction waste; The recycled aggregate from the brick-concrete construction waste includes three particle sizes: 10-30mm, 5-10mm, and 0-5mm. The percentages of these three particle sizes, expressed as mass percentages, are 40.0%-55.0%, 0.0%-10.0%, and 40.0%-50.0%, respectively. The recycled aggregate of cement concrete construction waste includes three particle sizes: 10-30mm, 5-10mm, and 0-5mm. The usage of these three sizes, by mass percentage, is 40.0%-50.0%, 30.0%-40.0%, and 10.0%-20.0%, respectively.

2. The bone-dense microporous sealed cement-stabilized building slag material according to claim 1, characterized in that, In the recycled aggregate of brick-concrete construction waste, the mass percentage of cement concrete blocks in the 10-30mm range is greater than 35%, and the mass percentage in the 5-10mm range is greater than 25%.

3. The bone-dense microporous sealed cement-stabilized building slag material according to claim 1, characterized in that, The sieve apertures for the synthetic gradation include 31.5mm, 19mm, 9.5mm, 4.75mm, 0.6mm, and 0.075mm, with corresponding passing percentage ranges of 100%~100%, 70%~85%, 45%~60%, 25%~35%, 5%~15%, and 0%~3%.

4. A method for preparing a bone-dense microporous sealed cement-stabilized building slag material as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1 involves recycling construction waste and then performing pre-treatment processes such as crushing, magnetic separation, air separation, and screening. Based on the type of original construction waste, recycled aggregates of brick-concrete construction waste or cement concrete construction waste are obtained and classified according to particle size. S2, mix the recycled aggregates of construction waste of different particle sizes evenly according to the design ratio to obtain the basic raw materials; S3, mix water and ethanol solution in the mass ratio and stir evenly, add water-soluble silane coupling agent and stir thoroughly to obtain strengthening solution, then immerse the base raw material in strengthening solution for wetting and strengthening. S4. Take out the impregnated and reinforced base material, dry it, add water to the base material minus 2% of the design water volume relative to the mass of the recycled construction waste aggregate, stir it thoroughly and let it stand. S5. After full impregnation, add the designed amount of cement and 2% of water relative to the mass percentage of recycled construction waste aggregate to the base raw materials, mix thoroughly and evenly to obtain the bone-dense microporous closed cement-stabilized construction waste material.

5. The application of a bone-dense microporous sealed cement-stabilized slag material as described in any one of claims 1 to 3 in the base course of airport runways and highway pavement structures.

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