Foamed asphalt concrete based on building solid waste recycled aggregate and preparation method thereof

Abstract

The application discloses a kind of foam asphalt concrete based on building solid waste recycled aggregate and preparation method thereof, including building solid waste recycled aggregate 99-101 parts, cement 1.3~1.8 parts, lime 0.8~1.2 parts, fiber 0.3~0.5 parts, water 10~13 parts, foam asphalt 3.2~3.7 parts.The preparation method of building solid waste recycled aggregate is as follows: first, soak, put silicate-containing wastewater and building solid waste recycled aggregate into airtight mixing device, so that silicate-containing wastewater completely submerges building solid waste recycled aggregate by 1~2 cm, soak for 4~7 h under normal temperature and pressure;second, mix, fill CO2 gas into the airtight mixing device after the first step of soaking, mix for 36~60 h under normal temperature and pressure when the pressure reaches 0.5~1.0 MPa, supplement CO2 gas every 4 h to ensure the pressure in the airtight mixing device is 0.5~1.0 MPa, and the rotation speed of the airtight mixing device is 25~35 r / min;third, clean, discharge silicate-containing wastewater from the airtight mixing device after the second step of mixing, and rinse building solid waste recycled aggregate with clean water;fourth, dry, take out building solid waste recycled aggregate after the third step of cleaning, and dry by baking or natural drying to obtain building solid waste recycled aggregate strengthened by silicate-containing wastewater.

Description

Technical Field

[0001] This invention belongs to the field of road engineering technology, specifically relating to a foamed asphalt concrete based on recycled aggregates from construction solid waste and its preparation method. Background Technology

[0002] In the field of road engineering, both domestically and internationally, the use of construction waste in road base or subbase layers has begun, and significant progress has been made in recent years. Recycling and reusing construction waste in road engineering can effectively address the shortage of natural resources such as sand, stone, and soil, as well as the environmental pollution caused by the large-scale stockpiling of construction waste. Although significant research has been conducted both domestically and internationally on the road performance of construction waste, many shortcomings remain. It faces numerous challenges, including limited application areas, low added value, and low utilization rates. Especially when used as recycled aggregate, it is generally only used in road base layers. While this approach achieves a high utilization rate of recycled aggregate, the added value is very low, failing to fully realize its value. The most significant application of recycled aggregate is in foamed asphalt concrete.

[0003] Foamed asphalt is an asphalt material in a foamed state. High-temperature asphalt is introduced into a foaming device and then exposed to a small amount of cold water, causing the surface area and volume of the asphalt to increase several times or even tens of times, forming foam materials of varying sizes but relatively uniform distribution. Currently, foamed asphalt is mainly used in the recycling field. Recycled asphalt pavement (RAP) is mixed with foamed asphalt to form foamed asphalt recycled mixtures, which are then compacted to form foamed asphalt concrete, primarily used in road base courses. Compared to hot-mix asphalt mixtures, foamed asphalt mixtures reduce CO2 production by 30% and dust emissions by 50%–60% during mixing, with energy consumption only 70% of that of hot-mix asphalt mixtures. However, due to the lower performance of its aggregates, it is generally only used in lower layers of asphalt pavements (lower layers or flexible base courses).

[0004] Recycled aggregates from construction solid waste suffer from defects such as numerous microcracks, high water absorption, and poor quality, making strengthening and modification an important method. Methods for strengthening recycled aggregates include: physical strengthening (mainly mechanical grinding), chemical strengthening (mainly soaking in chemical slurries), and nano-strengthening (mainly filling with nanomaterials). Physical strengthening typically requires specialized machinery, making the operation complex and offering limited performance improvements. Chemical strengthening causes significant environmental pollution and has limited effectiveness. Nano-strengthening offers better application results and overall benefits. It utilizes the micro-aggregate effect of nanomaterials to fill surface and internal cracks in recycled aggregates. Furthermore, nanomaterials are highly reactive and can undergo secondary hydration reactions with the Ca(OH)2 enriched in the pores of the old cement slurry interface, producing CSH gel that effectively fills pores and improves the old cement slurry interface. Nano-SiO2 exhibits the best strengthening effect, but this method is not economical, and there is room for improvement in its modification effect.

[0005] Currently, the use of newly formulated nano-strengthening liquids results in additional material waste and environmental pollution, and single-method strengthening treatments offer very limited performance improvements to recycled aggregates. Finding a technology with practical application value in terms of both economy and performance is key to solving the problem of recycled aggregate strengthening. The chemical industry generates large amounts of high-pH silicate-containing wastewater during production. Commonly used water treatment agents such as polyaluminum chloride (PAC), polyacrylamide (PAM), and polyacrylic acid are ineffective or have very poor effects on removing suspended solids from this wastewater, making treatment difficult. Systematic reports on the treatment of this type of wastewater have not yet been found. This application demonstrates that this silicate-containing wastewater, through certain technical means, has a significant strengthening effect on recycled aggregates from construction solid waste.

[0006] In their study, "Research on the Modification of Recycled Coarse Aggregate Properties by Chemical Fortification," Wei Hongjun et al. clarified the strengthening effects of nano-SiO2 and sodium silicate on recycled coarse aggregate. After treatment with optimal strengthening conditions using nano-SiO2 and sodium silicate, the water absorption rate of the recycled coarse aggregate decreased by 29.9% and 16.4%, respectively, and the crushing index decreased by 29.7% and 16.4%, respectively. The apparent density and bulk density were improved, approaching the levels of natural aggregate. The strengthening effect was in the order of nano-SiO2 > sodium silicate. Chinese Patent (CN202211359790.3) discloses a method for strengthening recycled aggregate, employing a "three-treatment method": first, acid soaking chemical treatment; then, autoclaving treatment; and finally, ball milling mechanical treatment. This "three-treatment method" significantly improves the physical properties and inherent strength of the recycled aggregate. However, "acid soaking" increases environmental and equipment costs, making it impractical. Chinese patent (CN202211422984.3) discloses a method for rapid carbonization of recycled aggregates from construction solid waste based on organic amines, which "uses organic amines to fix CO2 and improve the carbonization rate of recycled aggregates." Organic amines have significant advantages due to their chemical bonding properties, as they can react chemically with both recycled aggregates and CO2 in the environment. However, the application of organic amines increases the processing cost of recycled aggregates and does not have significant economic application value. Chinese patent (CN202211030326.X) discloses a method for strengthening recycled aggregates using a composite of nano-dispersion and chemical solution, which uses nano-SiO2 and calcium hydroxide to strengthen recycled aggregates (nano-dispersion and chemical solution composite strengthening). Although the strengthening effect is relatively obvious, it still uses newly configured strengthening materials and does not have a significant cost advantage.

[0007] The combination of foamed asphalt and recycled aggregates from construction waste can significantly reduce road construction costs and decrease carbon emissions and energy consumption during the construction period. However, the defects of recycled aggregates from construction waste in terms of asphalt adhesion and aggregate performance result in a low performance of foamed asphalt concrete prepared using recycled aggregates from construction waste, which affects its application areas and scope.

[0008] To address the shortcomings in the application performance of recycled aggregates from construction solid waste and the foamed asphalt concrete prepared therefrom, this invention provides a foamed asphalt concrete based on recycled aggregates from construction solid waste and its preparation method, aiming to improve the performance of recycled aggregates from construction solid waste and the foamed asphalt concrete prepared therefrom. Summary of the Invention

[0009] This invention discloses a foamed asphalt concrete based on recycled aggregate from construction solid waste and its preparation method, comprising the following components:

[0010] 99-101 parts recycled aggregate from construction solid waste, 0.5-2.0 parts cement, 0.5-1.5 parts lime, 0.1-0.5 parts fiber, 10-13 parts water, and 2.5-4.5 parts foamed asphalt;

[0011] The preparation of recycled aggregates from construction solid waste includes the following steps:

[0012] The first step is soaking. Silicate-containing wastewater and recycled aggregate from construction solid waste are placed in a closed mixing device, so that the silicate-containing wastewater completely submerges the recycled aggregate from construction solid waste by 1-2 cm. Soaking is carried out for 4-7 hours under normal temperature and pressure.

[0013] The second step is mixing. CO2 gas is introduced into the sealed mixing device after the first soaking treatment. When the pressure reaches 0.5-1.0 MPa, the mixing treatment is carried out at room temperature and pressure for 36-60 hours. During the mixing treatment, CO2 gas is added every 4 hours to ensure that the pressure in the sealed mixing device is 0.5-1.0 MPa. The rotation speed of the sealed mixing device is 25-35 r / min.

[0014] The third step is cleaning. The silicate-containing wastewater in the closed mixing device after the second step of mixing is discharged, and the recycled aggregate from construction solid waste is rinsed with clean water.

[0015] The fourth step is drying. The recycled aggregate from the construction solid waste that has been cleaned in the third step is released and dried by baking or air drying to obtain recycled aggregate from construction solid waste reinforced with silicate wastewater.

[0016] The silicate-containing wastewater is wastewater containing silicates generated during chemical production, with a pH value of 12-14, and the silicate content is 15-20 g / L (calculated as SiO2); the recycled aggregate from construction solid waste is recycled stone material formed after waste concrete blocks are crushed, screened, washed, and dried.

[0017] A method for preparing foamed asphalt concrete based on recycled aggregate from construction solid waste includes the following steps:

[0018] The first step is to mix 99-101 parts of recycled aggregate from construction solid waste, 0.5-2.0 parts of cement, 0.5-1.5 parts of lime, and 0.1-0.5 parts of fiber evenly.

[0019] The second step is to add 10 to 13 parts water to the materials obtained in the first step and continue to mix them evenly.

[0020] The third step is to add 2.5 to 4.5 parts of foamed asphalt to the material obtained in the second step and continue to mix evenly.

[0021] The fourth step is to compact the material obtained in the third step to obtain foamed asphalt concrete based on recycled aggregate from construction solid waste.

[0022] The present invention has the following advantages.

[0023] 1. Economic and environmental protection

[0024] By using silicate-containing wastewater to treat construction solid waste and recycle aggregates, the recycled aggregates are strengthened while the harmfulness of the wastewater is reduced. This saves wastewater generating units the cost of wastewater storage and treatment, and also saves recycled aggregate producing units the cost of purchasing strengthening raw materials. This ingenious combination of the two types of waste allows them to realize their respective values, reduces the pollution of waste to the environment, and creates new value.

[0025] 2. Improve the performance of recycled aggregates from construction solid waste

[0026] This method utilizes silicate-containing wastewater treatment to recycle construction solid waste into aggregates. It innovatively combines silicate strengthening with silica strengthening, employing both atmospheric and pressurized strengthening techniques to effectively improve the application performance of the recycled aggregates. The water absorption rate of the recycled aggregates can be increased by up to approximately 65.6%, and the crushing value by up to approximately 30.6%.

[0027] 3. Improve the overall performance of foamed asphalt concrete

[0028] The use of silicate-containing wastewater to treat recycled construction waste aggregates improved the adhesion between the recycled aggregates and asphalt. Using this recycled aggregate to prepare foamed asphalt concrete improved the overall performance of the foamed asphalt concrete. The unfrozen-thaw splitting strength reached approximately 0.56 MPa, a 36.6% increase compared to foamed asphalt concrete prepared with unreinforced recycled construction waste aggregates; the frozen-thaw splitting strength reached approximately 0.51 MPa, a 45.7% increase compared to foamed asphalt concrete prepared with unreinforced recycled construction waste aggregates; and the dynamic stability at 60℃ reached approximately 25,500 cycles, a 19.7% increase compared to foamed asphalt concrete prepared with unreinforced recycled construction waste aggregates. Although it still does not reach the level of natural stone, there are significant improvements. Detailed Implementation

[0029] Example 1

[0030] A foamed asphalt concrete based on recycled aggregate from construction solid waste and its preparation method, comprising the following components:

[0031] 99 parts recycled aggregate from construction solid waste, 1.3 parts cement, 0.8 parts lime, 0.3 parts fiber, 10 parts water, and 3.2 parts foamed asphalt;

[0032] The preparation of recycled aggregates from construction solid waste includes the following steps:

[0033] The first step is soaking. Silicate-containing wastewater and recycled aggregate from construction solid waste are placed in a closed mixing device, and the silicate-containing wastewater completely submerges the recycled aggregate from construction solid waste by 1-2 cm. The soaking treatment is carried out for 4 hours under normal temperature and pressure.

[0034] The second step is mixing. CO2 gas is introduced into the sealed mixing device after the first soaking treatment. When the pressure reaches 0.5 MPa, the device is mixed for 36 hours under normal temperature and pressure. During the mixing treatment, CO2 gas is added every 4 hours to ensure that the pressure in the sealed mixing device is 0.5 MPa. The rotation speed of the sealed mixing device is 25 r / min.

[0035] The third step is cleaning. The silicate-containing wastewater in the closed mixing device after the second step of mixing is discharged, and the recycled aggregate from construction solid waste is rinsed with clean water.

[0036] The fourth step is drying. The recycled aggregate from the construction solid waste that has been cleaned in the third step is released and dried by baking or air drying to obtain recycled aggregate from construction solid waste reinforced with silicate wastewater.

[0037] The silicate-containing wastewater is wastewater containing silicates generated during chemical production, with a pH value of 12, and the silicate content is 15 g / L (calculated as SiO2); the recycled aggregate from construction solid waste is recycled stone material formed after waste concrete blocks are crushed, screened, washed, and dried.

[0038] A method for preparing foamed asphalt concrete based on recycled aggregate from construction solid waste includes the following steps:

[0039] The first step is to mix 99 parts of recycled aggregate from construction solid waste, 1.3 parts of cement, 0.8 parts of lime, and 0.3 parts of fiber evenly.

[0040] The second step is to add 10 parts water to the materials obtained in the first step and continue to mix them evenly.

[0041] The third step is to add 3.2 parts of foamed asphalt to the material obtained in the second step and continue to mix evenly.

[0042] The fourth step is to compact the material obtained in the third step to obtain foamed asphalt concrete based on recycled aggregate from construction solid waste.

[0043] Example 2

[0044] A foamed asphalt concrete based on recycled aggregate from construction solid waste and its preparation method, comprising the following components:

[0045] 100 parts recycled aggregate from construction solid waste, 1.4 parts cement, 0.9 parts lime, 0.4 parts fiber, 11 parts water, and 3.4 parts foamed asphalt;

[0046] The preparation of recycled aggregates from construction solid waste includes the following steps:

[0047] The first step is soaking. Silicate-containing wastewater and recycled aggregate from construction solid waste are placed in a closed mixing device, and the silicate-containing wastewater completely submerges the recycled aggregate from construction solid waste by 1-2 cm. The soaking treatment is carried out for 4 hours under normal temperature and pressure.

[0048] The second step is mixing. CO2 gas is introduced into the sealed mixing device after the first soaking treatment. When the pressure reaches 0.5 MPa, the device is mixed at room temperature and pressure for 38 hours. During the mixing treatment, CO2 gas is added every 4 hours to ensure that the pressure in the sealed mixing device is 0.5 MPa and the rotation speed of the sealed mixing device is 28 r / min.

[0049] The third step is cleaning. The silicate-containing wastewater in the closed mixing device after the second step of mixing is discharged, and the recycled aggregate from construction solid waste is rinsed with clean water.

[0050] The fourth step is drying. The recycled aggregate from the construction solid waste that has been cleaned in the third step is released and dried by baking or air drying to obtain recycled aggregate from construction solid waste reinforced with silicate wastewater.

[0051] The silicate-containing wastewater is wastewater containing silicates generated during chemical production, with a pH value of 13 and a silicate content of 18 g / L (calculated as SiO2); the recycled aggregate from construction solid waste is recycled stone material formed after waste concrete blocks are crushed, screened, washed, and dried.

[0052] A method for preparing foamed asphalt concrete based on recycled aggregate from construction solid waste includes the following steps:

[0053] The first step is to mix 100 parts of recycled aggregate from construction solid waste, 1.4 parts of cement, 0.9 parts of lime, and 0.4 parts of fiber evenly.

[0054] The second step is to add 11 parts water to the materials obtained in the first step and continue to mix them evenly.

[0055] The third step is to add 3.4 parts of foamed asphalt to the material obtained in the second step and continue to mix evenly.

[0056] The fourth step is to compact the material obtained in the third step to obtain foamed asphalt concrete based on recycled aggregate from construction solid waste.

[0057] Example 3

[0058] A foamed asphalt concrete based on recycled aggregate from construction solid waste and its preparation method, comprising the following components:

[0059] 100 parts recycled aggregate from construction solid waste, 1.6 parts cement, 1.1 parts lime, 0.5 parts fiber, 12 parts water, and 3.6 parts foamed asphalt;

[0060] The preparation of recycled aggregates from construction solid waste includes the following steps:

[0061] The first step is soaking. Silicate-containing wastewater and recycled aggregate from construction solid waste are placed in a closed mixing device, and the silicate-containing wastewater completely submerges the recycled aggregate from construction solid waste by 1-2 cm. The soaking treatment is carried out at normal temperature and pressure for 4.5 hours.

[0062] The second step is mixing. CO2 gas is introduced into the sealed mixing device after the first soaking treatment. When the pressure reaches 0.6 MPa, the mixing treatment is carried out at room temperature and pressure for 40 hours. During the mixing treatment, CO2 gas is added every 4 hours to ensure that the pressure in the sealed mixing device is 0.6 MPa. The rotation speed of the sealed mixing device is 30 r / min.

[0063] The third step is cleaning. The silicate-containing wastewater in the closed mixing device after the second step of mixing is discharged, and the recycled aggregate from construction solid waste is rinsed with clean water.

[0064] The fourth step is drying. The recycled aggregate from the construction solid waste that has been cleaned in the third step is released and dried by baking or air drying to obtain recycled aggregate from construction solid waste reinforced with silicate wastewater.

[0065] The silicate-containing wastewater is wastewater containing silicates generated during chemical production, with a pH value of 12, and the silicate content is 17 g / L as SiO2; the recycled aggregate from construction solid waste is recycled stone material formed after waste concrete blocks are crushed, screened, washed, and dried.

[0066] A method for preparing foamed asphalt concrete based on recycled aggregate from construction solid waste includes the following steps:

[0067] The first step is to mix 100 parts of recycled aggregate from construction solid waste, 1.6 parts of cement, 1.1 parts of lime, and 0.5 parts of fiber evenly.

[0068] The second step is to add 12 parts water to the materials obtained in the first step and continue to mix them evenly.

[0069] The third step is to add 3.6 parts of foamed asphalt to the material obtained in the second step and continue to mix evenly.

[0070] The fourth step is to compact the material obtained in the third step to obtain foamed asphalt concrete based on recycled aggregate from construction solid waste.

[0071] Example 4

[0072] A foamed asphalt concrete based on recycled aggregate from construction solid waste and its preparation method, comprising the following components:

[0073] 99 parts recycled aggregate from construction solid waste, 1.3 parts cement, 0.8 parts lime, 0.3 parts fiber, 10 parts water, and 3.3 parts foamed asphalt;

[0074] The preparation of recycled aggregates from construction solid waste includes the following steps:

[0075] The first step is soaking. Silicate-containing wastewater and recycled aggregate from construction solid waste are placed in a closed mixing device, and the silicate-containing wastewater completely submerges the recycled aggregate from construction solid waste by 1-2 cm. The soaking treatment is carried out for 5 hours under normal temperature and pressure.

[0076] The second step is mixing. CO2 gas is introduced into the sealed mixing device after the first soaking treatment. When the pressure reaches 0.6 MPa, the device is mixed at room temperature and pressure for 42 hours. During the mixing treatment, CO2 gas is added every 4 hours to ensure that the pressure in the sealed mixing device is 0.6 MPa. The rotation speed of the sealed mixing device is 35 r / min.

[0077] The third step is cleaning. The silicate-containing wastewater in the closed mixing device after the second step of mixing is discharged, and the recycled aggregate from construction solid waste is rinsed with clean water.

[0078] The fourth step is drying. The recycled aggregate from the construction solid waste that has been cleaned in the third step is released and dried by baking or air drying to obtain recycled aggregate from construction solid waste reinforced with silicate wastewater.

[0079] The silicate-containing wastewater is wastewater containing silicates generated during chemical production, with a pH value of 14 and a silicate content of 16 g / L (calculated as SiO2). The recycled aggregate from construction solid waste is recycled stone material formed after waste concrete blocks are crushed, screened, washed, and dried.

[0080] A method for preparing foamed asphalt concrete based on recycled aggregate from construction solid waste includes the following steps:

[0081] The first step is to mix 99 parts of recycled aggregate from construction solid waste, 1.3 parts of cement, 0.8 parts of lime, and 0.3 parts of fiber evenly.

[0082] The second step is to add 10 parts water to the materials obtained in the first step and continue to mix them evenly.

[0083] The third step is to add 3.3 parts of foamed asphalt to the material obtained in the second step and continue to mix evenly.

[0084] The fourth step is to compact the material obtained in the third step to obtain foamed asphalt concrete based on recycled aggregate from construction solid waste.

[0085] Example 5

[0086] A foamed asphalt concrete based on recycled aggregate from construction solid waste and its preparation method, comprising the following components:

[0087] 100 parts recycled aggregate from construction solid waste, 1.5 parts cement, 1.0 part lime, 0.4 parts fiber, 12 parts water, and 3.5 parts foamed asphalt;

[0088] The preparation of recycled aggregates from construction solid waste includes the following steps:

[0089] The first step is soaking. Silicate-containing wastewater and recycled aggregate from construction solid waste are placed in a closed mixing device, and the silicate-containing wastewater completely submerges the recycled aggregate from construction solid waste by 1-2 cm. The soaking treatment is carried out for 5 hours under normal temperature and pressure.

[0090] The second step is mixing. CO2 gas is introduced into the sealed mixing device after the first soaking treatment. When the pressure reaches 0.7 MPa, the device is mixed at room temperature and pressure for 45 hours. During the mixing treatment, CO2 gas is added every 4 hours to ensure that the pressure in the sealed mixing device is 0.7 MPa. The rotation speed of the sealed mixing device is 26 r / min.

[0091] The third step is cleaning. The silicate-containing wastewater in the closed mixing device after the second step of mixing is discharged, and the recycled aggregate from construction solid waste is rinsed with clean water.

[0092] The fourth step is drying. The recycled aggregate from the construction solid waste that has been cleaned in the third step is released and dried by baking or air drying to obtain recycled aggregate from construction solid waste reinforced with silicate wastewater.

[0093] The silicate-containing wastewater is wastewater containing silicates generated during chemical production, with a pH value of 13 and a silicate content of 15 g / L (calculated as SiO2); the recycled aggregate from construction solid waste is recycled stone material formed after waste concrete blocks are crushed, screened, washed, and dried.

[0094] A method for preparing foamed asphalt concrete based on recycled aggregate from construction solid waste includes the following steps:

[0095] The first step is to mix 100 parts of recycled aggregate from construction solid waste, 1.5 parts of cement, 1.0 part of lime, and 0.4 parts of fiber evenly.

[0096] The second step is to add 12 parts water to the materials obtained in the first step and continue to mix them evenly.

[0097] The third step is to add 3.5 parts of foamed asphalt to the material obtained in the second step and continue to mix evenly.

[0098] The fourth step is to compact the material obtained in the third step to obtain foamed asphalt concrete based on recycled aggregate from construction solid waste.

[0099] Example 6

[0100] A foamed asphalt concrete based on recycled aggregate from construction solid waste and its preparation method, comprising the following components:

[0101] 101 parts recycled aggregate from construction solid waste, 1.6 parts cement, 1.1 parts lime, 0.5 parts fiber, 13 parts water, and 3.6 parts foamed asphalt;

[0102] The preparation of recycled aggregates from construction solid waste includes the following steps:

[0103] The first step is soaking. Silicate-containing wastewater and recycled aggregate from construction solid waste are placed in a closed mixing device, so that the silicate-containing wastewater completely submerges the recycled aggregate from construction solid waste by 1-2 cm. The soaking treatment is carried out at normal temperature and pressure for 5.5 hours.

[0104] The second step is mixing. CO2 gas is introduced into the sealed mixing device after the first soaking treatment. When the pressure reaches 0.7 MPa, the device is mixed at room temperature and pressure for 48 hours. During the mixing treatment, CO2 gas is added every 4 hours to ensure that the pressure in the sealed mixing device is 0.7 MPa. The rotation speed of the sealed mixing device is 29 r / min.

[0105] The third step is cleaning. The silicate-containing wastewater in the closed mixing device after the second step of mixing is discharged, and the recycled aggregate from construction solid waste is rinsed with clean water.

[0106] The fourth step is drying. The recycled aggregate from the construction solid waste that has been cleaned in the third step is released and dried by baking or air drying to obtain recycled aggregate from construction solid waste reinforced with silicate wastewater.

[0107] The silicate-containing wastewater is wastewater containing silicates generated during chemical production, with a pH value of 13 and a silicate content of 17 g / L (calculated as SiO2); the recycled aggregate from construction solid waste is recycled stone material formed after waste concrete blocks are crushed, screened, washed, and dried.

[0108] A method for preparing foamed asphalt concrete based on recycled aggregate from construction solid waste includes the following steps:

[0109] The first step is to mix 101 parts of recycled aggregate from construction solid waste, 1.6 parts of cement, 1.1 parts of lime, and 0.5 parts of fiber evenly.

[0110] The second step is to add 13 parts water to the materials obtained in the first step and continue to mix them evenly.

[0111] The third step is to add 3.6 parts of foamed asphalt to the material obtained in the second step and continue to mix evenly.

[0112] The fourth step is to compact the material obtained in the third step to obtain foamed asphalt concrete based on recycled aggregate from construction solid waste.

[0113] Example 7

[0114] A foamed asphalt concrete based on recycled aggregate from construction solid waste and its preparation method, comprising the following components:

[0115] 99 parts recycled aggregate from construction solid waste, 1.4 parts cement, 0.9 parts lime, 0.3 parts fiber, 11 parts water, and 3.4 parts foamed asphalt;

[0116] The preparation of recycled aggregates from construction solid waste includes the following steps:

[0117] The first step is soaking. Silicate-containing wastewater and recycled aggregate from construction solid waste are placed in a closed mixing device, and the silicate-containing wastewater completely submerges the recycled aggregate from construction solid waste by 1-2 cm. The soaking treatment is carried out for 6 hours under normal temperature and pressure.

[0118] The second step is mixing. CO2 gas is introduced into the sealed mixing device after the first soaking treatment. When the pressure reaches 0.8 MPa, the device is mixed at room temperature and pressure for 50 hours. During the mixing treatment, CO2 gas is added every 4 hours to ensure that the pressure in the sealed mixing device is 0.8 MPa. The rotation speed of the sealed mixing device is 32 r / min.

[0119] The third step is cleaning. The silicate-containing wastewater in the closed mixing device after the second step of mixing is discharged, and the recycled aggregate from construction solid waste is rinsed with clean water.

[0120] The fourth step is drying. The recycled aggregate from the construction solid waste that has been cleaned in the third step is released and dried by baking or air drying to obtain recycled aggregate from construction solid waste reinforced with silicate wastewater.

[0121] The silicate-containing wastewater is wastewater containing silicates generated during chemical production, with a pH value of 14, and the silicate content is 18 g / L as SiO2; the recycled aggregate from construction solid waste is recycled stone material formed after waste concrete blocks are crushed, screened, washed, and dried.

[0122] A method for preparing foamed asphalt concrete based on recycled aggregate from construction solid waste includes the following steps:

[0123] The first step is to mix 99 parts of recycled aggregate from construction solid waste, 1.4 parts of cement, 0.9 parts of lime, and 0.3 parts of fiber evenly.

[0124] The second step is to add 11 parts water to the materials obtained in the first step and continue to mix them evenly.

[0125] The third step is to add 3.4 parts of foamed asphalt to the material obtained in the second step and continue to mix evenly.

[0126] The fourth step is to compact the material obtained in the third step to obtain foamed asphalt concrete based on recycled aggregate from construction solid waste.

[0127] Example 8

[0128] A foamed asphalt concrete based on recycled aggregate from construction solid waste and its preparation method, comprising the following components:

[0129] 100 parts recycled aggregate from construction solid waste, 1.5 parts cement, 1.0 part lime, 0.4 parts fiber, 12 parts water, and 3.5 parts foamed asphalt;

[0130] The preparation of recycled aggregates from construction solid waste includes the following steps:

[0131] The first step is soaking. Silicate-containing wastewater and recycled aggregate from construction solid waste are placed in a closed mixing device, and the silicate-containing wastewater completely submerges the recycled aggregate from construction solid waste by 1-2 cm. The soaking treatment is carried out for 6 hours under normal temperature and pressure.

[0132] The second step is mixing. CO2 gas is introduced into the sealed mixing device after the first soaking treatment. When the pressure reaches 0.8 MPa, the device is mixed at room temperature and pressure for 53 hours. During the mixing treatment, CO2 gas is added every 4 hours to ensure that the pressure in the sealed mixing device is 0.8 MPa. The rotation speed of the sealed mixing device is 28 r / min.

[0133] The third step is cleaning. The silicate-containing wastewater in the closed mixing device after the second step of mixing is discharged, and the recycled aggregate from construction solid waste is rinsed with clean water.

[0134] The fourth step is drying. The recycled aggregate from the construction solid waste that has been cleaned in the third step is released and dried by baking or air drying to obtain recycled aggregate from construction solid waste reinforced with silicate wastewater.

[0135] The silicate-containing wastewater is wastewater containing silicates generated during chemical production, with a pH value of 13 and a silicate content of 20 g / L (calculated as SiO2). The recycled aggregate from construction solid waste is recycled stone material formed after waste concrete blocks are crushed, screened, washed, and dried.

[0136] A method for preparing foamed asphalt concrete based on recycled aggregate from construction solid waste includes the following steps:

[0137] The first step is to mix 100 parts of recycled aggregate from construction solid waste, 1.5 parts of cement, 1.0 part of lime, and 0.4 parts of fiber evenly.

[0138] The second step is to add 12 parts water to the materials obtained in the first step and continue to mix them evenly.

[0139] The third step is to add 3.5 parts of foamed asphalt to the material obtained in the second step and continue to mix evenly.

[0140] The fourth step is to compact the material obtained in the third step to obtain foamed asphalt concrete based on recycled aggregate from construction solid waste.

[0141] Example 9

[0142] A foamed asphalt concrete based on recycled aggregate from construction solid waste and its preparation method, comprising the following components:

[0143] 101 parts recycled aggregate from construction solid waste, 1.7 parts cement, 1.2 parts lime, 0.5 parts fiber, 13 parts water, and 3.7 parts foamed asphalt;

[0144] The preparation of recycled aggregates from construction solid waste includes the following steps:

[0145] The first step is soaking. Silicate-containing wastewater and recycled aggregate from construction solid waste are placed in a closed mixing device, and the silicate-containing wastewater completely submerges the recycled aggregate from construction solid waste by 1-2 cm. The soaking treatment is carried out for 6.5 hours under normal temperature and pressure.

[0146] The second step is mixing. CO2 gas is introduced into the sealed mixing device after the first soaking treatment. When the pressure reaches 0.9 MPa, the mixing treatment is carried out at room temperature and pressure for 55 hours. During the mixing treatment, CO2 gas is added every 4 hours to ensure that the pressure in the sealed mixing device is 0.9 MPa. The rotation speed of the sealed mixing device is 33 r / min.

[0147] The third step is cleaning. The silicate-containing wastewater in the closed mixing device after the second step of mixing is discharged, and the recycled aggregate from construction solid waste is rinsed with clean water.

[0148] The fourth step is drying. The recycled aggregate from the construction solid waste that has been cleaned in the third step is released and dried by baking or air drying to obtain recycled aggregate from construction solid waste reinforced with silicate wastewater.

[0149] The silicate-containing wastewater is wastewater containing silicates generated during chemical production, with a pH value of 12, and the silicate content is 16 g / L as SiO2; the recycled aggregate from construction solid waste is recycled stone material formed after waste concrete blocks are crushed, screened, washed, and dried.

[0150] A method for preparing foamed asphalt concrete based on recycled aggregate from construction solid waste includes the following steps:

[0151] The first step is to mix 101 parts of recycled aggregate from construction solid waste, 1.7 parts of cement, 1.2 parts of lime, and 0.5 parts of fiber evenly.

[0152] The second step is to add 13 parts water to the materials obtained in the first step and continue to mix them evenly.

[0153] The third step is to add 3.7 parts of foamed asphalt to the material obtained in the second step and continue to mix evenly.

[0154] The fourth step is to compact the material obtained in the third step to obtain foamed asphalt concrete based on recycled aggregate from construction solid waste.

[0155] Example 10

[0156] A foamed asphalt concrete based on recycled aggregate from construction solid waste and its preparation method, comprising the following components:

[0157] 101 parts recycled aggregate from construction solid waste, 1.8 parts cement, 1.2 parts lime, 0.5 parts fiber, 13 parts water, and 3.7 parts foamed asphalt;

[0158] The preparation of recycled aggregates from construction solid waste includes the following steps:

[0159] The first step is soaking. Silicate-containing wastewater and recycled aggregate from construction solid waste are placed in a closed mixing device, and the silicate-containing wastewater completely submerges the recycled aggregate from construction solid waste by 1-2 cm. The soaking treatment is carried out for 7 hours under normal temperature and pressure.

[0160] The second step is mixing. CO2 gas is introduced into the sealed mixing device after the first soaking treatment. When the pressure reaches 1.0 MPa, the mixing treatment is carried out at room temperature and pressure for 60 hours. During the mixing treatment, CO2 gas is added every 4 hours to ensure that the pressure in the sealed mixing device is 1.0 MPa. The rotation speed of the sealed mixing device is 35 r / min.

[0161] The third step is cleaning. The silicate-containing wastewater in the closed mixing device after the second step of mixing is discharged, and the recycled aggregate from construction solid waste is rinsed with clean water.

[0162] The fourth step is drying. The recycled aggregate from the construction solid waste that has been cleaned in the third step is released and dried by baking or air drying to obtain recycled aggregate from construction solid waste reinforced with silicate wastewater.

[0163] The silicate-containing wastewater is wastewater containing silicates generated during chemical production, with a pH value of 14, and the silicate content is 15 g / L (calculated as SiO2); the recycled aggregate from construction solid waste is recycled stone material formed after waste concrete blocks are crushed, screened, washed, and dried.

[0164] A method for preparing foamed asphalt concrete based on recycled aggregate from construction solid waste includes the following steps:

[0165] The first step is to mix 101 parts of recycled aggregate from construction solid waste, 1.8 parts of cement, 1.2 parts of lime, and 0.5 parts of fiber evenly.

[0166] The second step is to add 13 parts water to the materials obtained in the first step and continue to mix them evenly.

[0167] The third step is to add 3.7 parts of foamed asphalt to the material obtained in the second step and continue to mix evenly.

[0168] The fourth step is to compact the material obtained in the third step to obtain foamed asphalt concrete based on recycled aggregate from construction solid waste.

[0169] Application effects of the examples

[0170] In accordance with the relevant provisions of the "Technical Specification for Highway Recycling" (JTGT 5521-2019) and the "Technical Specification for Highway Asphalt Pavement Construction" (JTGF40-2004), the performance of the silicate waste-recycled aggregates reinforced with silicate wastewater and the foamed asphalt concrete prepared therefrom, the unreinforced recycled aggregates of construction solid waste and the foamed asphalt concrete prepared therefrom, and the natural stone and the foamed asphalt concrete prepared therefrom were tested. The performance is shown in the table below.

[0171] Table 1 Technical performance of silicate-containing wastewater-reinforced recycled aggregates from building solid waste applied to foamed asphalt concrete

[0172]

[0173]

[0174] Note: 1. The "Technical Specification for Construction of Asphalt Pavement of Highway" specifies that the asphalt adhesion of aggregates in each layer of highways of other grades (excluding expressways and Class I highways) is Level 4 in humid areas and Level 3 in arid and semi-arid areas.

[0175] 2. The "Technical Specification for Construction of Asphalt Pavement of Highways" stipulates that the water absorption rate of aggregates in each layer of highways of other grades (excluding expressways and Class I highways) shall be ≤3%.

[0176] 3. The "Technical Specification for Construction of Asphalt Pavement of Highways" stipulates that the crushing value of aggregates in each layer of highways of other grades (excluding expressways and Class I highways) shall be ≤30%.

[0177] As shown in the table, regarding the asphalt adhesion of aggregates, the asphalt adhesion of unreinforced recycled construction waste aggregates is only level 2 or 1, far below the level 3 or 4 required by relevant specifications, and even further below the level 4 or 5 of natural stone. Reinforced recycled construction waste aggregates can reach level 3, 4, or 5, showing a significant overall improvement, and previously non-compliant recycled stone now meets the specifications. Regarding the water absorption rate of aggregates, the water absorption rate of unreinforced recycled construction waste aggregates is 6.4%, significantly higher than that of natural stone and failing to meet the specifications. However, the water absorption rate of reinforced recycled construction waste aggregates shows a significant improvement; the water absorption rate of reinforced recycled construction waste aggregates in Examples 6-10 can reach 2.2-2.8%, meeting the specifications. Regarding the crushing value of aggregates, the crushing value of unreinforced recycled building waste aggregates is 17.3%, which meets the specification requirements, but there is still a certain gap compared with natural stone. The crushing value of recycled building waste aggregates after reinforcement has been significantly improved. The crushing value of reinforced recycled building waste aggregates in Examples 6 to 10 can reach 12 to 12.6%, which is close to the crushing value of natural stone.

[0178] After preparing foamed asphalt concrete from various aggregates and conducting performance tests, it can be seen that the various properties of foamed asphalt concrete have been significantly improved, although they still cannot reach the level of natural stone. In Examples 6-10, the unfrozen splitting strength remained stable at approximately 0.56 MPa, an increase of 36.6%; the freeze-thaw splitting strength remained stable at approximately 0.51 MPa, an increase of 45.7%; the freeze-thaw splitting strength ratio remained stable at approximately 91%, an increase of 6.6%; and the dynamic stability remained stable at approximately 25,500 cycles, an increase of 19.7%.

Claims

1. A foamed asphalt concrete based on recycled aggregate from construction solid waste reinforced with silicate wastewater, characterized in that: It contains the following components: The mixture comprises 99-101 parts of recycled aggregate from construction solid waste enhanced with silicate wastewater, 1.3-1.8 parts of cement, 0.8-1.2 parts of lime, 0.3-0.5 parts of fiber, 10-13 parts of water, and 3.2-3.7 parts of foamed asphalt; the preparation of the recycled aggregate from construction solid waste enhanced with silicate wastewater includes the following steps: The first step is soaking. Silicate-containing wastewater and recycled aggregate from construction solid waste are placed in a closed mixing device, so that the silicate-containing wastewater completely submerges the recycled aggregate from construction solid waste by 1-2 cm. Soaking is carried out for 4-7 hours under normal temperature and pressure. The second step is mixing. CO2 gas is introduced into the sealed mixing device after the first soaking treatment. When the pressure reaches 0.5-1.0 MPa, the mixing treatment is carried out at room temperature and pressure for 36-60 hours. During the mixing treatment, CO2 gas is added every 4 hours to ensure that the pressure in the sealed mixing device is 0.5-1.0 MPa. The rotation speed of the sealed mixing device is 25-35 r / min. The third step is cleaning. The silicate-containing wastewater in the closed mixing device after the second step of mixing is discharged, and the recycled aggregate from construction solid waste is rinsed with clean water. The fourth step is drying. The recycled aggregate from the construction solid waste after the third step of cleaning is released and dried by baking or air drying to obtain recycled aggregate from construction solid waste reinforced with silicate wastewater. The silicate-containing wastewater is wastewater containing silicates generated during chemical production, with a pH value of 12-14, and the silicate content is 15-20 g / L as SiO2; the recycled aggregate from construction solid waste is recycled stone material formed after waste concrete blocks are crushed, screened, washed, and dried.

2. A method for preparing foamed asphalt concrete based on silicate-containing wastewater-reinforced recycled aggregate from construction solid waste as described in claim 1, characterized in that, It includes the following steps: The first step is to mix 99-101 parts of recycled aggregate from construction solid waste reinforced with silicate wastewater, 1.3-1.8 parts of cement, 0.8-1.2 parts of lime, and 0.3-0.5 parts of fiber evenly. The second step is to add 10 to 13 parts water to the materials obtained in the first step and continue to mix them evenly. The third step is to add 3.2 to 3.7 parts of foamed asphalt to the material obtained in the second step and continue to mix evenly. The fourth step is to compact the material obtained in the third step to obtain foamed asphalt concrete based on recycled aggregate from construction solid waste reinforced with silicate wastewater.

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