A kind of building waste recycled composite subgrade filler and its preparation method

Abstract

The present invention relates to the technical field of mortar and concrete compositions, and particularly relates to a building waste recycled composite subgrade filler and a preparation method thereof. The building waste recycled composite subgrade filler is composed of building waste and mineral admixtures; the mineral admixtures are one or more of fly ash, silica fume, slag powder, limestone powder, phosphorus slag powder, and zeolite powder. Compared with the prior art, the building waste recycled composite subgrade filler of the present invention organically combines two kinds of wastes, namely building waste and mineral admixtures, gives play to their respective advantages, and solves the problems of high-quality recycling of solid waste and shortage of sand and gravel materials in highway construction. It can be applied to the preparation of building waste fully recycled concrete for precast components in highway construction such as conical slopes, arched skeletons, and side ditch paving, and can improve the impermeability and frost resistance performance at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of mortar concrete compositions, and particularly to a building waste recycled composite subgrade filler and a preparation method thereof. Background Art

[0002] CN115716729A discloses an industrial building waste negative carbon subgrade filler and a preparation method thereof, including S1, preparing a negative carbon gel material using industrial waste, and S2, recycling a negative carbon subgrade filler using building waste. This invention uses industrial waste and building waste as the main materials, achieving the resourceful recycling and comprehensive utilization of both. The advantages of both complement each other, which can alleviate problems such as land occupation and environmental pollution caused by the current accumulation of solid waste; using recycled negative carbon reinforced coarse aggregate from building waste can reduce the dependence on natural sand and gravel materials in engineering construction; it provides a new way for the insufficient supply of current subgrade fillers; the preparation process of the negative carbon subgrade filler is simple, which can be prepared on-site or centrally processed in factories around the city, with a short transportation distance and low cost, effectively reducing the disposal pressure of industrial building waste and improving the disposal efficiency.

[0003] CN111393065A discloses a building waste recycled composite subgrade filler and a preparation method thereof. The subgrade filler is composed of the following materials by mass percentage: 5 - 70% of brick and concrete recycled aggregate, 5 - 75% of mud cake filler, 1 - 10% of hydrated lime, 1 - 10% of fly ash, 0.5 - 4% of HEC, and 10 - 20% of water. This invention's building waste recycled composite subgrade filler has high strength and small drying shrinkage, and realizes the resourceful utilization of building waste such as waste clay bricks, waste concrete, and mud cakes, solving the pollution problem of landfill disposal of building waste and the environmental damage caused by the exploitation of natural fillers, and alleviating the current shortage of natural resources.

[0004] The solutions reported in the above patent documents do not simultaneously solve the impermeability and frost resistance performance. Summary of the Invention

[0005] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a building waste fully recycled concrete that can be applied to the preparation of precast components in highway construction such as conical slopes, arched skeletons, and side ditch paving, and can simultaneously improve the impermeability and frost resistance performance.

[0006] To achieve the above object, the present invention provides a building waste recycled composite subgrade filler and a preparation method thereof.

[0007] The building waste recycled composite subgrade filler is composed of building waste and mineral admixtures.

[0008] The building waste and mineral admixtures are mixed in a mass ratio of 6 - 8:2 - 4.

[0009] The mineral admixture is one or more of fly ash, silica fume, slag powder, limestone powder, phosphorus slag powder, and zeolite powder.

[0010] The mineral admixture is a mixture of fly ash and slag powder.

[0011] The mineral admixture is prepared by mixing fly ash and slag powder in a mass ratio of 2 - 4:1 - 2.

[0012] The preparation method of the construction waste is as follows, by weight:

[0013] (1) Feed 80 - 120 parts of waste concrete into a crusher for primary crushing, and then feed it into a screening machine for screening, which is divided into large - sized solid waste and small - sized solid waste;

[0014] (2) Feed the large - sized solid waste and small - sized solid waste into a crusher for secondary crushing respectively, and then feed them into a screening machine for screening respectively. Feed the materials after secondary screening into a water - washing machine for water - washing, and obtain 40 - 110 parts of recycled coarse aggregate and 10 - 40 parts of recycled fine aggregate through air classification;

[0015] (3) Mix 5 - 7 parts of tannic acid aqueous solution and 3 - 5 parts of gelatin aqueous solution, stir at a speed of 5000 - 6000 r / min for 20 - 40 minutes, dry, grind and sieve, and then add it to 4 - 6 parts of ethylene glycol aqueous solution for dilution to obtain a composite binder;

[0016] (4) Mix 8 - 12 parts of phase - change wax and 4 - 6 parts of nano - montmorillonite, place it under a vacuum condition of 80 - 90 kPa and stir for 6 - 8 hours until adsorption is complete to obtain doped nano - montmorillonite;

[0017] (5) Add 50 - 70 parts of recycled coarse aggregate, 10 - 20 parts of composite binder, and 10 - 20 parts of doped nano - montmorillonite to 100 - 150 parts of water, stir at a speed of 2000 - 4000 r / min for 1 - 2 hours to make the doped nano - montmorillonite completely adhere to the surface of the recycled coarse aggregate for shaping, dry until the moisture content is lower than 2.0 wt%, and finally mix it with the recycled fine aggregate to obtain the construction waste.

[0018] In step (1), the large particle size is 10 - 50 mm, and the small particle size is 1 - 10 mm.

[0019] In step (1), the particle size of the recycled coarse aggregate is 5 - 30 mm, and the particle size of the recycled fine aggregate is 1 - 5 mm.

[0020] In step (3), the tannic acid aqueous solution is a 5 - 10 wt% tannic acid aqueous solution.

[0021] In step (3), the gelatin aqueous solution is a 4 - 6 wt% gelatin aqueous solution.

[0022] In step (3), the ethylene glycol aqueous solution is a 40-60 wt% ethylene glycol aqueous solution.

[0023] The preparation method of the building waste recycled composite subgrade filler is as follows:

[0024] Mix the building waste and mineral admixture to obtain the building waste recycled composite subgrade filler.

[0025] The building waste recycled composite subgrade filler of the present invention organically combines two kinds of wastes, building waste and mineral admixture, and gives full play to their respective advantages. Among them, the building waste is obtained by crushing, screening, shaping, mixing, etc. with waste concrete as the raw material. The mineral admixture refers to a powder material mainly composed of one or more oxides such as silicon, aluminum, and calcium, with a specified fineness, and can improve the performance of concrete when incorporated into concrete. The composite mineral admixture in the building waste recycled composite subgrade filler of the present invention is one or more of fly ash, silica fume, slag powder, limestone powder, phosphorus slag powder, and zeolite powder. Fly ash, as a mineral admixture, can be widely used in concrete. Fly ash is the powder collected from the flue gas of a pulverized coal boiler; silica fume is the dust discharged through the flue during the smelting of ferrosilicon alloy or industrial silicon, and is a powder material mainly composed of amorphous silica obtained by collection; slag powder refers to a powdery material obtained by drying and finely grinding granulated blast furnace slag to a certain fineness and meeting the corresponding activity index, and its activity is higher than that of fly ash; limestone powder is a powdery material obtained by grinding limestone with a certain purity to the specified fineness; phosphorus slag powder is a powder material obtained by grinding the melt mainly composed of calcium silicate obtained during the production of yellow phosphorus by the electric furnace method after quenching into pellets; zeolite powder is a powder material obtained by grinding natural clinoptilolite rock or mordenite rock.

[0026] The beneficial effects of the present invention:

[0027] Compared with the prior art, the building waste recycled composite subgrade filler of the present invention organically combines two kinds of wastes, building waste and mineral admixture, and gives full play to their respective advantages, solving the problems of high-quality recycling of solid waste and shortage of sand and gravel materials in highway construction. It can be applied to the preparation of building waste fully recycled concrete for precast components in highway construction such as conical slopes, arched skeletons, and side ditch paving, and can improve the impermeability and frost resistance at the same time. Specific embodiments

[0028] The parameters of the specific chemical substances used in the examples are as follows:

[0029] Nano montmorillonite: 50 nm, manufactured by Tuoyi New Materials (Guangzhou) Co., Ltd., model TY-710C.

[0030] Nano silica: 20 nm, manufactured by Qinghe County Chaotai Metal Materials Co., Ltd., brand SF93.

[0031] Nano-calcined kaolin: 50 nm, manufactured by Tuoyi New Materials (Guangzhou) Co., Ltd., model TY-209.

[0032] Fly ash: manufactured by Wuhan Jiyesheng Chemical Co., Ltd., product number A01085.

[0033] Ground granulated blast-furnace slag: S95 grade ground granulated blast-furnace slag.

[0034] Tannic acid: purity 81%, molecular weight 1701.2, extracted from Chinese gallnut, 95% passes through 80 mesh, manufactured by Shaanxi Haochen Biotechnology Co., Ltd.

[0035] Phase change wax: heat point 21 ± 2 °C, melting heat ≥ 190 J / g, manufactured by Nanyang Energy Chemical Co., Ltd. , model NYXC-21.

[0036] Water reducing agent: manufactured by Jiangsu Sobute New Materials Co., Ltd., model SBTJM®-Ⅷ.

[0037] Example 1

[0038] A kind of building waste recycled composite subgrade filler is composed of 7 parts by weight of building waste and 3 parts by weight of fly ash.

[0039] The preparation method of the building waste is as follows:

[0040] (1) Feed 1000 g of waste concrete into a crusher for primary crushing, and then into a screening machine for screening, which is divided into large-size waste with a particle size of 10 - 50 mm and small-size waste with a particle size of 1 - 10 mm;

[0041] (2) Feed the large-size waste and small-size waste into a crusher for secondary crushing respectively, and then into a screening machine for screening respectively. Feed the materials after secondary screening into a water washing machine for water washing, and obtain 700 g of recycled coarse aggregate with a particle size of 5 - 30 mm and 300 g of recycled fine aggregate with a particle size of 1 - 5 mm through air classification; Mix the recycled coarse aggregate and the recycled fine aggregate to obtain the building waste.

[0042] The preparation method of the building waste recycled composite subgrade filler is as follows:

[0043] Mix 7 parts by weight of building waste and 3 parts by weight of fly ash to obtain the building waste recycled composite subgrade filler.

[0044] Example 2

[0045] A kind of building waste recycled composite subgrade filler is composed of 7 parts by weight of building waste and 3 parts by weight of ground granulated blast-furnace slag.

[0046] The preparation method of the construction waste is as follows:

[0047] (1) Feed 1000 g of waste concrete into a crusher for primary crushing, and then feed it into a screening machine for screening, which is divided into large-sized waste with a particle size of 10 - 50 mm and small-sized waste with a particle size of 1 - 10 mm;

[0048] (2) Feed the large-sized waste and small-sized waste into a crusher for secondary crushing respectively, and then feed them into a screening machine for screening respectively. Feed the materials after secondary screening into a water washing machine for water washing, and obtain 700 g of recycled coarse aggregate with a particle size of 5 - 30 mm and 300 g of recycled fine aggregate with a particle size of 1 - 5 mm through air classification; Mix the recycled coarse aggregate and the recycled fine aggregate to obtain the construction waste.

[0049] The preparation method of the construction waste recycled composite subgrade filler is as follows:

[0050] Mix 7 parts by weight of construction waste and 3 parts by weight of slag powder to obtain the construction waste recycled composite subgrade filler.

[0051] Example 3

[0052] A construction waste recycled composite subgrade filler is composed of 7 parts by weight of construction waste, 2 parts by weight of fly ash, and 1 part by weight of slag powder.

[0053] The preparation method of the construction waste is as follows:

[0054] (1) Feed 1000 g of waste concrete into a crusher for primary crushing, and then feed it into a screening machine for screening, which is divided into large-sized waste with a particle size of 10 - 50 mm and small-sized waste with a particle size of 1 - 10 mm;

[0055] (2) Feed the large-sized waste and small-sized waste into a crusher for secondary crushing respectively, and then feed them into a screening machine for screening respectively. Feed the materials after secondary screening into a water washing machine for water washing, and obtain 700 g of recycled coarse aggregate with a particle size of 5 - 30 mm and 300 g of recycled fine aggregate with a particle size of 1 - 5 mm through air classification; Mix the recycled coarse aggregate and the recycled fine aggregate to obtain the construction waste.

[0056] The preparation method of the construction waste recycled composite subgrade filler is as follows:

[0057] Mix 7 parts by weight of construction waste, 2 parts by weight of fly ash, and 1 part by weight of slag powder to obtain the construction waste recycled composite subgrade filler.

[0058] Example 4

[0059] A construction waste recycled composite subgrade filler is composed of 7 parts by weight of construction waste, 2 parts by weight of fly ash, and 1 part by weight of slag powder.

[0060] The preparation method of the construction waste is as follows:

[0061] (1) Feed 1000 g of waste concrete into a crusher for primary crushing, and then feed it into a screening machine for screening, which is divided into large-size waste with a particle size of 10 - 50 mm and small-size waste with a particle size of 1 - 10 mm;

[0062] (2) Feed the large-size waste and small-size waste into a crusher for secondary crushing respectively, and then feed them into a screening machine for screening respectively. Feed the materials after secondary screening into a water washing machine for water washing, and obtain 700 g of recycled coarse aggregate with a particle size of 5 - 30 mm and 300 g of recycled fine aggregate with a particle size of 1 - 5 mm through air classification;

[0063] (3) Mix 60 g of 8 wt% tannic acid aqueous solution and 40 g of 5 wt% gelatin aqueous solution, stir at a speed of 5500 r / min for 30 minutes, dry, grind and sieve, and then add it to 50 g of 50 wt% ethylene glycol aqueous solution for dilution to obtain a composite binder;

[0064] (4) Mix 100 g of phase change wax and 50 g of nano-montmorillonite, place it under a vacuum condition of 85 kPa and stir for 7 hours until adsorption is complete to obtain doped nano-montmorillonite;

[0065] (5) Add 700 g of recycled coarse aggregate, 150 g of composite binder, and 150 g of doped nano-montmorillonite to 1600 g of water, stir at a speed of 3000 r / min for 1.5 hours to make the doped nano-montmorillonite completely adhere to the surface of the recycled coarse aggregate for shaping, dry until the moisture content is lower than 2.0 wt%, and finally mix it with 300 g of recycled fine aggregate to obtain the construction waste.

[0066] The preparation method of the construction waste recycled composite subgrade filler is as follows:

[0067] Mix 7 parts by weight of construction waste, 2 parts by weight of fly ash, and 1 part by weight of slag powder to obtain the construction waste recycled composite subgrade filler.

[0068] Example 5

[0069] A construction waste recycled composite subgrade filler is composed of 7 parts by weight of construction waste, 2 parts by weight of fly ash, and 1 part by weight of slag powder.

[0070] The preparation method of the construction waste is as follows:

[0071] (1) Feed 1000 g of waste concrete into a crusher for primary crushing, and then feed it into a screening machine for screening, which is divided into large-size waste with a particle size of 10 - 50 mm and small-size waste with a particle size of 1 - 10 mm;

[0072] (2) Feed the large - sized solid waste and small - sized solid waste into a crusher for secondary crushing respectively, then feed them into a screening machine for screening respectively. Feed the materials after secondary screening into a water - washing machine for water - washing, and obtain 700 g of recycled coarse aggregate with a particle size of 5 - 30 mm and 300 g of recycled fine aggregate with a particle size of 1 - 5 mm through air classification;

[0073] (3) Mix 60 g of 8 wt% tannic acid aqueous solution and 40 g of 5 wt% gelatin aqueous solution, stir at a speed of 5500 r / min for 30 minutes, dry, grind and sieve, and then add it to 50 g of 50 wt% ethylene glycol aqueous solution for dilution to obtain a composite binder;

[0074] (4) Mix 100 g of phase - change wax and 50 g of nano - silica, place it under a vacuum condition of 85 kPa and stir for 7 hours until adsorption is complete to obtain doped nano - montmorillonite;

[0075] (5) Add 700 g of recycled coarse aggregate, 150 g of composite binder, and 150 g of doped nano - montmorillonite to 1600 g of water, stir at a speed of 3000 r / min for 1.5 hours to make the doped nano - montmorillonite completely adhere to the surface of the recycled coarse aggregate for shaping, dry until the moisture content is lower than 2.0 wt%, and finally mix it with 300 g of recycled fine aggregate to obtain the said construction solid waste.

[0076] The preparation method of the recycled composite subgrade filler from construction solid waste is as follows:

[0077] Mix 7 parts by weight of construction solid waste, 2 parts by weight of fly ash, and 1 part by weight of slag powder to obtain the recycled composite subgrade filler from construction solid waste.

[0078] Example 6

[0079] A recycled composite subgrade filler from construction solid waste is composed of 7 parts by weight of construction solid waste, 2 parts by weight of fly ash, and 1 part by weight of slag powder.

[0080] The preparation method of the said construction solid waste is as follows:

[0081] (1) Feed 1000 g of waste concrete into a crusher for primary crushing, and then feed it into a screening machine for screening, which is divided into large - sized solid waste with a particle size of 10 - 50 mm and small - sized solid waste with a particle size of 1 - 10 mm;

[0082] (2) Feed the large - sized solid waste and small - sized solid waste into a crusher for secondary crushing respectively, then feed them into a screening machine for screening respectively. Feed the materials after secondary screening into a water - washing machine for water - washing, and obtain 700 g of recycled coarse aggregate with a particle size of 5 - 30 mm and 300 g of recycled fine aggregate with a particle size of 1 - 5 mm through air classification;

[0083] (3) Mix 60 g of 8 wt% tannic acid aqueous solution and 40 g of 5 wt% gelatin aqueous solution, stir at 5500 r / min for 30 minutes, dry, grind and sieve, and add it to 50 g of 50 wt% ethylene glycol aqueous solution for dilution to obtain a composite binder;

[0084] (4) Mix 100 g of phase change wax and 50 g of nano-calcined kaolin, place it under a vacuum condition of 85 kPa and stir for 7 hours until adsorption is complete to obtain doped nano-montmorillonite;

[0085] (5) Add 700 g of recycled coarse aggregate, 150 g of composite binder, and 150 g of doped nano-montmorillonite to 1600 g of water, stir at 3000 r / min for 1.5 hours to make the doped nano-montmorillonite completely adhere to the surface of the recycled coarse aggregate for shaping, dry until the moisture content is lower than 2.0 wt%, and finally mix with 300 g of recycled fine aggregate to obtain the building solid waste.

[0086] The preparation method of the recycled composite subgrade filler of the building solid waste is as follows:

[0087] Mix 7 parts by weight of building solid waste, 2 parts by weight of fly ash, and 1 part by weight of slag powder to obtain the recycled composite subgrade filler of the building solid waste.

[0088] Application Examples 1-6

[0089] Recycled concrete from building solid waste, the specific preparation method is as follows:

[0090] Add 400 g of cement, 1000 g of the recycled composite subgrade filler of building solid waste in Examples 1-6, and 5 g of water reducing agent to 300 g of water, stir at room temperature for 1 hour to obtain recycled concrete from building solid waste.

[0091] Test Example 1

[0092] Conduct an impermeability performance test on the recycled concrete from building solid waste in Application Examples 1-4. The impermeability performance test refers to the relative permeability test in the industry standard SL / T 352-2020 "Test Code for Hydraulic Concrete". Use the standard test mold specified in the specification to prepare specimens. After the specimens are formed and demolded, use a wire brush to brush off the cement slurry film on both ends of the test block, and then cure in the curing room. After curing to the age, take out the specimens and wipe them clean. Add the water pressure of the impermeability tester to 0.8 MPa at one time, keep it constant at this pressure for 24 h, and then reduce the pressure and stop the machine; when the concrete is relatively dense, change the water pressure to 1.2 MPa, and start the test after keeping it constant at this pressure for 24 h. Set 6 specimens for each example, calculate their relative permeability coefficients and take the average value and summarize as shown in Table 1.

[0093] The formula for the relative permeability coefficient is as follows: K r =aD 2m / 2tH = 7.66×10 -8 ×D 2 m

[0094] Where:

[0095] K r ——Coefficient of relative permeability of concrete, cm / h;

[0096] D m ——Seepage height of the specimen, cm;

[0097] H——Water pressure, expressed as the height of a water column, cm, 1 MPa water pressure is expressed as 10200 cm in terms of the height of a water column;

[0098] t——Constant pressure time, h;

[0099] a——Water absorption rate of concrete, which can be taken as 0.03.

[0100] Take the average value of the measured values of 6 specimens as the test result (rounding interval 0.1×10 -8 cm / h).

[0101] Table 1 Test results of impermeability performance

[0102] Application Example 1 Application Example 2 Application Example 3 Application Example 4 Relative Permeability Coefficient (cm / h) <![CDATA[0.50×10 -8 > <![CDATA[0.47×10 -8 > <![CDATA[0.43×10 -8 > <![CDATA[0.29×10 -8 >

[0103] In Application Example 1 and Application Example 2, in the preparation of the construction waste recycled composite subgrade filler, construction waste is mixed with fly ash or slag powder. In Application Example 3 and Application Example 4, construction waste is mixed with fly ash and slag powder. It can be seen from the table that the impermeability performance of Application Example 3 - 4 is better than that of Application Example 1 - 2. One of the reasons is that the synergistic effect of fly ash and slag powder improves the impermeability performance of concrete. The two can undergo a secondary reaction with substances such as calcium hydroxide generated by cement hydration to form more gel substances, filling the pores inside the concrete, making the structure more dense, and being able to better improve the microscopic structure of the concrete, thereby enhancing its impermeability performance. The second reason is that the particle sizes of fly ash and slag powder form a particle size gradient with cement and construction waste, and the particles fill each other, further reducing the voids between fine aggregate particles, making it more dense, reducing the number and size of connected pores, and thus reducing the channels for water penetration. And in Application Example 4, on the basis of Application Example 3, a composite binder and doped nano - montmorillonite are added during the preparation of construction waste to conduct special treatment on the surface of recycled coarse aggregate. Different components and treatment methods will affect the pore structure and density inside the concrete, etc., resulting in different coefficients of relative permeability. The coefficient of relative permeability of Application Example 4 is the smallest, and its water impermeability performance is the best.

[0104] Test Example 2

[0105] The chloride ion penetration resistance test of the construction waste recycled concrete of Application Examples 1-4 was carried out by the dry-wet cycling method. 3 groups of specimens were set for each application example. The specimens with the length, width and height of 100mm×100mm×200mm were placed with the top surface facing up into a 3.0wt% sodium chloride solution (weigh 30g of sodium chloride and dissolve it in 970g of deionized water), and the immersion depth was 5cm. After soaking for 24h, they were taken out and air-dried. After 1h, they were put into an oven and baked at 60℃ for 45h. After drying, they were taken out and cooled for 2h, and then put into the sodium chloride solution for soaking again, and the immersion depth was 5cm. The total time from the start of soaking to baking was 720h; then, concrete powder specimens were drilled longitudinally along the central axis on both side surfaces of the specimens at a depth of 15cm, and the soluble chloride ion content in the specimens was analyzed by chemical titration method. The summary is shown in Table 2.

[0106] Table 2 Test results of chloride ion resistance performance

[0107] Application Example 1 Application Example 2 Application Example 3 Application Example 4 Chloride Ion % 0.018 0.016 0.013 0.010

[0108] The construction waste recycled composite subgrade filler added to the construction waste recycled concrete of Application Examples 1-4 uses construction waste as the basic material, which provides the basic skeleton structure and certain mechanical properties for the recycled concrete. Among them, there may be some factors that are not conducive to impermeability in the pore structure and surface characteristics, etc., which will provide channels for the penetration of chloride ions. In Application Examples 1 and 2, fly ash and slag powder are added respectively to act together with construction waste. In Application Example 3, fly ash and slag powder act together with construction waste. In Application Example 4, the construction waste is specially treated on the basis of Application Example 3. Chloride ions can diffuse through non-pore paths such as microcracks and capillary pores inside the concrete. Among them, fly ash makes it more dense and reduces pores; the active silica and alumina in fly ash can react with calcium hydroxide generated by cement hydration to form stable calcium silicate hydrate, thereby filling the microcracks and pores in the concrete and enhancing the compactness of the concrete; the slag powder and fly ash act together to make the internal structure of the concrete more dense, and the synergistic effect of the two makes the chloride ion penetration resistance performance better than that of Application Examples 1-2 with only one of fly ash or slag powder added.

[0109] Test Example 3

[0110] The frost resistance test of the construction waste recycled concrete of Application Examples 3-6 was carried out. 5 groups of specimens were set for each application example. The specimen size was 100mm×100mm×20mm, and the specimen age was 30d. The salt frost test was carried out on the surface of the specimens through a freeze-thaw device, and the surface spalling amount of the specimens after freeze-thaw was measured to measure the surface frost resistance of the specimens. The test was carried out according to the national standard GB / T 35723-2017 "Rapid Test Method for Surface Salt Frost Resistance of Concrete Pavement Bricks", and the spalling quantity per unit area was calculated and the average value was summarized as shown in Table 3.

[0111] The calculation formula is as follows: N = m / A × 10 -6

[0112] Where:

[0113] N—the spalling amount per unit area of the specimen, in grams per square meter (g / m 2 );

[0114] m—the total mass of the spalled material on the test surface after 25 freeze-thaw cycles, in grams (g);

[0115] A—the area of the test surface, in square millimeters (mm).

[0116] The test results are expressed as the arithmetic mean and the maximum value of 5 specimens.

[0117] Table 3 Test results of frost resistance performance

[0118] Application Example 3 Application Example 4 Application 5 Application 6 Spalling Amount per Unit Area <![CDATA[1.49 g / m 2 > <![CDATA[1.40 g / m 2 > <![CDATA[1.43 g / m 2 > <![CDATA[1.44 g / m 2 >

[0119] In Application Example 3-4, the spalling amount per unit area of concrete was effectively reduced through the combined action of slag powder and fly ash. By reducing the porosity of concrete, deicing salts are less likely to enter and remain in the concrete, thereby improving the salt frost resistance of concrete and reducing the spalling amount per unit area of concrete. On the basis of Application Example 3, Application Example 4 carried out special treatment on the surface of recycled coarse aggregate during the preparation of construction waste. In Application Example 4, when preparing construction waste, composite binder was used to adhere doped nano-montmorillonite to the surface of recycled coarse aggregate, making its shape smoother and flatter, and distributing more evenly and tightly in the application of concrete. The composite binder is prepared from tannic acid aqueous solution and gelatin aqueous solution. The composite binder has low-temperature weather resistance and still maintains adhesiveness in low-temperature environment, avoiding the problem of easy freezing and loss of viscosity in practical applications. Ethylene glycol can effectively dilute and disperse the active components in the binder, and helps to improve the fluidity and adhesion performance of the binder; gelatin is a protein polymer containing a large number of polar amino acid residues such as serine and aspartic acid, and these residues endow gelatin with good film-forming property and gel property; tannic acid is a natural organic compound with various biological activities, and forms hydrogen bonds with polar amino acid residues in fibroin through its abundant hydroxyl groups to achieve adhesiveness, making the combination of doped nano-montmorillonite and recycled coarse aggregate more stable; at the same time, it better resists the damage of external stress, reduces the spalling of the concrete surface, reduces the spalling amount per unit area, and improves the frost resistance.

[0120] The nano-montmorillonite in Application Example 4 has a large specific surface area and good adsorption properties. After being treated with recycled coarse aggregates and applied to concrete, the adsorption property of the nano-montmorillonite can adsorb and combine the phase change material, phase change wax, under pressure conditions. When the phase change wax undergoes a phase change, it can buffer the stress concentration areas generated inside the concrete due to temperature changes to a certain extent, making the internal stress distribution of the concrete more uniform, thereby reducing the occurrence of cracks or peeling caused by the destruction of the structure due to stress concentration, and improving its frost resistance. From the perspective of the filling effect, doping nano-montmorillonite enables it to come into fuller contact with the recycled coarse aggregates. After the two are combined, they can fill the pores of various sizes originally existing inside the concrete, making the concrete structure more compact. The compact structure effectively blocks the channels for water penetration and reduces the possibility of water entering the interior of the concrete during the freeze-thaw process. In terms of optimizing the pore structure, the combination of nano-montmorillonite and recycled coarse aggregates refines the spatial structure compared with the unshaped recycled coarse aggregates. The more uniform distribution can effectively reduce the migration speed of water inside the concrete, further reducing the damage caused by the freezing and expansion of water to the concrete. The optimization of the pore structure synergistically works with the functions of preventing water penetration and enhancing densification, making the concrete in this embodiment have better frost resistance in a low-temperature environment. In Application Examples 5 and 6, nano-silica and nano-calcined kaolin are respectively used to replace nano-montmorillonite on the basis of Application Example 4. Although they also have high activity and a certain filling effect, their particle morphologies and surface properties are not completely the same. Although they can fill the internal pores of the concrete to a certain extent and improve the microstructure of the concrete, compared with nano-montmorillonite, their adsorption properties are relatively weak. When combined with the phase change wax, they cannot effectively adsorb the phase change wax and disperse it evenly in the concrete system like nano-montmorillonite, resulting in a worse effect in resisting the stress concentration generated by temperature changes than nano-montmorillonite, and making the uniformity of the internal stress distribution of the concrete slightly worse. Therefore, the spalling amount per unit area in Test Example 3 of Application Examples 5 - 6 is slightly higher than that of Application Example 4.

[0121] The preferred specific embodiments of the present invention have been described in detail above. It should be understood that those of ordinary skill in the art can make many modifications and variations based on the concept of the present invention without creative efforts. Therefore, all technical solutions that can be obtained by those skilled in the art in the technical field of the present invention based on the concept of the present invention through logical analysis, reasoning, or limited experiments on the basis of the prior art should fall within the protection scope determined by the claims.

Claims

1. A composite roadbed filler made of recycled construction solid waste, characterized by: The construction solid waste recycled composite roadbed filler is composed of construction solid waste and mineral admixtures; The construction solid waste and the mineral admixture are mixed in a mass ratio of 6-8:2-4; The mineral admixture is one or more of fly ash, silica ash, slag powder, limestone powder, phosphorus slag powder and zeolite powder; The preparation method of the construction solid waste is as follows, in parts by weight: (1) 80-120 parts of waste concrete are sent to a crusher for primary crushing, and then sent to a screening machine for screening to separate solid waste with large particle size and solid waste with small particle size; (2) The large-size solid waste and the small-size solid waste are respectively sent to a crusher for secondary crushing, and are respectively sent to a screening machine for screening. The secondary screened materials are sent to a washing machine for washing, and 40-110 parts of recycled coarse aggregate and 10-40 parts of recycled fine aggregate are obtained by wind classification; (3) Mix 5-7 parts of tannic acid aqueous solution and 3-5 parts of gelatin aqueous solution, stir at 5000-6000 r / min for 20-40 minutes, dry, grind and sieve, and add to 4-6 parts of ethylene glycol aqueous solution for dilution to obtain a composite adhesive; (4) Mix 8-12 parts of phase change wax and 4-6 parts of nano-montmorillonite, place under 80-90 kPa vacuum conditions and stir for 6-8 hours until adsorption is complete to obtain doped nano-montmorillonite; (5) Add 50-70 parts of recycled coarse aggregate, 10-20 parts of composite adhesive, and 10-20 parts of doped nano-montmorillonite to 100-150 parts of water, stir at a speed of 2000-4000 r / min for 1-2 hours to allow the doped nano-montmorillonite to completely adhere to the surface of the recycled coarse aggregate for shaping, dry until the moisture content is less than 2.0wt%, and finally mix with recycled fine aggregate to obtain the construction solid waste.

2. The construction solid waste recycled composite roadbed filler according to claim 1, characterized in that: The mineral admixture is a mixture of fly ash and slag powder.

3. The construction solid waste recycled composite roadbed filler as claimed in claim 2, characterized in that: The mineral admixture is a mixture of fly ash and slag powder in a mass ratio of 2-4:1-2.

4. The construction solid waste recycled composite roadbed filler according to claim 1, characterized in that: In the step (1), the large particle size is 10-50 mm, and the small particle size is 1-10 mm.

5. The construction solid waste recycled composite roadbed filler according to claim 1, characterized in that: In the step (2), the particle size of the recycled coarse aggregate is 5-30 mm, and the particle size of the recycled fine aggregate is 1-5 mm.

6. The construction solid waste recycled composite roadbed filler according to claim 1, characterized in that: The tannic acid aqueous solution in step (3) is a 5-10 wt % tannic acid aqueous solution.

7. The construction solid waste recycled composite roadbed filler as claimed in claim 1, characterized in that: The gelatin aqueous solution in step (3) is a 4-6 wt % gelatin aqueous solution.

8. The construction solid waste recycled composite roadbed filler as claimed in claim 1, characterized in that: The ethylene glycol aqueous solution in step (3) is a 40-60wt% ethylene glycol aqueous solution.

9. The method for preparing the composite roadbed filler from construction solid waste as claimed in any one of claims 1 to 8, characterized in that: The preparation method is as follows: The construction solid waste and mineral admixture are mixed to obtain the construction solid waste recycled composite roadbed filler.