A carbonized γ-C2S modified salt-storing slow-release ceramsite, its preparation method and application

Abstract

The application belongs to the technical field of building materials, and discloses a carbonized gamma-C2S modified salt-storing slow-release ceramsite as well as a preparation method and application thereof. First, a porous ceramsite is treated with an inhibitor and a surfactant to obtain active ceramsite; then the active ceramsite is soaked in a saturated solution of deicing salt to obtain salt-storing ceramsite; then the salt-storing ceramsite is treated with a temperature-sensitive agent to obtain salt-storing slow-release ceramsite; finally, the salt-storing slow-release ceramsite is modified by carbonized gamma-C2S to form a core-shell structure with the salt-storing slow-release ceramsite as the core and the carbonized gamma-C2S as the shell, thereby obtaining the carbonized gamma-C2S modified salt-storing slow-release ceramsite. The ceramsite prepared by the application has the comprehensive performance of lightweight, high strength, strong salt-storing capacity and good slow-release effect, and when applied to asphalt pavement materials, can play a long-acting deicing effect and ensure good road performance, thereby having a wide application prospect in regions with much snow in winter in China.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a carbonized γ-C2S modified salt-storing slow-release ceramsite, its preparation method, and its application. Background Technology

[0002] As the most important transportation infrastructure, highways directly determine the quality and efficiency of a country's economic development. In northern regions, frequent temperature fluctuations and long, harsh winters make roads prone to icing and snow accumulation after rain, snow, or water-soaked brakes. This significantly reduces tire adhesion, leading to vehicle power loss and loss of control, resulting in accidents. Traffic congestion and vehicle delays caused by icy and snow-covered roads are frequent occurrences. Conventional snow removal methods primarily involve manual snow removal, machine snow removal, and the application of de-icing agents. However, manual and machine snow removal are inefficient, and prolonged operations disrupt traffic flow. Applying de-icing agents can easily lead to over-application, causing long-term corrosion and damage to road surfaces and drainage systems, shortening road lifespan, and impacting the surrounding environment.

[0003] In recent years, some scholars at home and abroad have found that adding salt-retaining aggregates to road concrete allows the de-icing salts in the aggregates to precipitate and penetrate the road surface to melt snow and prevent road icing under the influence of vehicle compaction, pore osmotic pressure, and capillary action. Compared with the traditional method of spreading de-icing agents, the snow-melting and de-icing effect of salt-retaining aggregate pavements is more significant, requiring less salt and reducing damage to concrete structures and environmental pollution. Furthermore, compared with other active anti-icing technologies, its process is simpler and less expensive. Therefore, the incorporation of salt-retaining aggregates is considered an effective measure to improve the anti-icing performance of high-performance concrete roads.

[0004] However, existing salt-absorbing aggregates have some performance defects, making it difficult to achieve the expected results in practical use. Some salt-absorbing aggregates suffer from poor release stability due to improper snow-melting salt storage methods. Excessive release of snow-melting salt in the early stages not only makes the snow-melting effect unsustainable but also negatively impacts the environment near highways, causing soil salinization and damaging surrounding greenery. Some salt-absorbing aggregates use porous carriers such as natural zeolite to control the release rate of snow-melting salt, but due to the high closed porosity and low apparent porosity of the internal pores, their salt absorption and storage capacity is limited, and their long-term snow-melting function still needs improvement. Furthermore, with the increasing prevalence of heavy-load and high-volume traffic, higher demands are being placed on the strength of salt-absorbing aggregates.

[0005] In conclusion, it is necessary to develop a salt storage aggregate that simultaneously considers salt storage capacity, slow release effect, and strength, so that it can be used in harsh environments with high altitude, cold, and heavy snow. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the shortcomings of the existing technology by providing a carbonized γ-C2S modified salt-storing slow-release ceramsite, its preparation method and application. The ceramsite has comprehensive properties such as lightweight and high strength, strong salt storage capacity and good slow-release effect. When applied to asphalt pavement materials, it can play a long-term snow melting and de-icing effect and ensure good road performance.

[0007] To address the technical problem proposed in this invention, this invention provides a method for preparing carbonized γ-C2S modified salt-storing slow-release ceramsite, comprising the following steps:

[0008] 1) Add porous ceramsite, corrosion inhibitor, and surfactant to anhydrous ethanol, let it stand and soak, then stir and soak again, remove and dry to obtain activated ceramsite;

[0009] 2) Prepare a saturated salt solution from the snow-melting salt, soak the activated ceramic particles in the saturated salt solution, remove them and dry them to obtain salt-accumulating ceramic particles;

[0010] 3) Dissolve the temperature-sensitive agent in heated anhydrous ethanol, then add salt-accumulating ceramsite, soak under ultraviolet light irradiation, remove and dry to obtain salt-accumulating slow-release ceramsite;

[0011] 4) Mix γ-C2S with water evenly to make γ-C2S slurry; add pore-forming agent, foam stabilizer and thickener to water and stir at high speed to make foam; pour the foam into γ-C2S slurry and stir evenly to obtain porous γ-C2S slurry.

[0012] 5) Soak the salt-storing slow-release ceramsite in water and then remove it to obtain pre-wetted salt-storing slow-release ceramsite; add the pre-wetted salt-storing slow-release ceramsite to porous γ-C2S slurry and stir, then cure, carbonize and dry in sequence to obtain carbonized γ-C2S modified salt-storing slow-release ceramsite.

[0013] In the above scheme, the porous ceramsite is made by mixing fly ash and red mud, granulating, and then sintering.

[0014] Furthermore, the mass ratio of the fly ash to the red mud is 100:(50-80).

[0015] Furthermore, the sintering temperature is 1150–1250℃, and the sintering time is 10–15 min.

[0016] In the above scheme, the porous ceramsite has a particle size of 2.36–4.75 mm, a compressive strength ≥ 5.0 MPa, an apparent porosity ≥ 30%, and an apparent density ≤ 1.4 g·cm³. -3 .

[0017] In the above scheme, the corrosion inhibitor is one or more of sodium tetraborate, sodium dihydrogen phosphate, sodium tripolyphosphate, and sodium silicate.

[0018] In the above scheme, the surfactant is one of silane coupling agents, aluminate coupling agents, zirconium aluminate coupling agents, and organochromium coupling agents.

[0019] In the above scheme, in step 1), the mass ratio of the porous ceramic particles, corrosion inhibitor, and surfactant is 100:(8-15):(5-8).

[0020] In the above scheme, in step 1), the soaking time is 1.5 to 2.5 hours.

[0021] In the above scheme, in step 1), the stirring rate of the stirring and soaking is 50-100 r / min, and the stirring and soaking time is 3-5 h.

[0022] In the above scheme, the snow-melting salt is a mixture of chloride salt and sodium acetate.

[0023] Furthermore, the chloride salt is at least one of sodium chloride and calcium chloride.

[0024] Furthermore, the mass ratio of the chloride salt to sodium acetate is 100:(30-60).

[0025] In the above scheme, in step 2), the mass ratio of the active ceramic particles to the snow-melting salt is 100:(30-60).

[0026] In the above scheme, in step 2), the temperature of the saturated salt solution is 65-75℃.

[0027] In the above scheme, in step 2), the soaking time is 24 to 36 hours.

[0028] In the above scheme, the temperature-sensitive agent is prepared by heating poly(N-isopropylacrylamide) (PNIPAM), glycidyl methacrylate, and 2,2-azobis(2-methylpropylimidazolium) and the reaction has a low critical solution temperature (LCST) of 18-22°C.

[0029] Further, the mass ratio of poly(N-isopropylacrylamide), glycidyl methacrylate, and 2,2-azobis(2-methylpropylimidazolium) is 100:(4-6):(0.5-0.8).

[0030] Furthermore, the heating temperature during the preparation of the temperature-sensitive agent is 75–90°C, and the reaction time is 1.5–2.0 h.

[0031] Furthermore, the heating reaction in the preparation process of the temperature-sensitive agent is carried out under stirring conditions, with a stirring rate of 200–300 r / min.

[0032] In the above scheme, in step 3), the mass ratio of the salt storage ceramic particles to the temperature-sensitive agent is 100:(2-8).

[0033] In the above scheme, in step 3), the temperature of the anhydrous ethanol is maintained at 55-65°C.

[0034] In the above scheme, in step 3), the intensity of the ultraviolet light is 7-9 mW / cm². 2 .

[0035] In the above scheme, in step 3), the soaking time is 4 to 6 hours.

[0036] In the above scheme, the γ-C2S is obtained by ball milling steel slag and sandstone at a calcium-silicon molar ratio of 2:1, pressing the mixture into a raw material blank, and then drying and calcining it, with a specific surface area ≥300m². 2 / kg.

[0037] Furthermore, the calcination temperature in the γ-C2S preparation process is 1350–1380℃, and the calcination time is 3–3.5 h.

[0038] In the above scheme, the pore-forming agent is one or two of sodium dodecyl sulfate (K12), sodium fatty alcohol polyoxyethylene ether sulfate (AES), and sodium α-alkenyl sulfonate (AOS).

[0039] In the above scheme, the foam stabilizer is one of trihydroxyolefin polyether (GP) and silicone polyether emulsion (MPS).

[0040] In the above scheme, the thickener is one or more of methylcellulose, methylhydroxyethylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxyethylpropylcellulose, and hydroxypropylmethylcellulose.

[0041] In the above scheme, the density of the foam is 48-52 kg / m³. 3 .

[0042] In the above scheme, in step 4), the mass ratio of γ-C2S, γ-C2S slurry preparation water, pore-forming agent, foam stabilizer, thickener, and foam preparation water is 100:(32~60):(0.8~6):(0.8~4):(4~8):(12~20).

[0043] In the above scheme, in step 4), the stirring rate after the foam is poured into the γ-C2S slurry is 50-100 r / min and the stirring time is 50-70 s.

[0044] In the above scheme, in step 5), the mass ratio of the salt-storing slow-release ceramsite to the porous γ-C2S slurry is 100:(30-50).

[0045] In the above scheme, in step 5), the soaking time is 4 to 6 hours.

[0046] In the above scheme, in step 5), the stirring rate is 50-100 r / min and the stirring time is 70-90 s.

[0047] In the above scheme, in step 5), the curing temperature is 20-25℃ and the curing time is 2-3 days.

[0048] In the above scheme, the carbonization conditions in step 5) are: temperature 50-60℃, CO2 volume concentration 50-80%, relative pressure 0.1-0.12MPa, and carbonization time 4-8h.

[0049] In the above scheme, in steps 1), 2), 3), and 5), the drying temperature is 80-90℃ and the drying time is 1-2 hours.

[0050] The present invention also provides a carbonized γ-C2S modified salt-storage slow-release ceramsite, which is prepared by the above method.

[0051] In the above scheme, the carbonized γ-C2S modified salt-storing slow-release ceramsite has a particle size of 3-5 mm, a compressive strength ≥7.5 MPa, an apparent porosity of 20-30%, and an apparent density ≤1.5 g·cm³. -3 .

[0052] This invention also provides an application of carbonized γ-C2S modified salt-storage slow-release ceramsite in asphalt pavement materials. The application method is as follows: carbonized γ-C2S modified salt-storage slow-release ceramsite is used to replace the fine aggregate with a particle size of 3-5mm in the asphalt mixture by an equal volume to obtain an asphalt mixture with salt-storage slow-release function.

[0053] In the above scheme, the asphalt mixture is one of SMA-13, AC-13, SMA-10, and AC-10.

[0054] In the above scheme, the volume substitution rate of the carbonized γ-C2S modified salt-storing slow-release ceramsite for 3-5mm fine aggregate is ≥40%. Compared with the prior art, the beneficial effects of the present invention are:

[0055] 1) The carbonized γ-C2S modified salt-storage and slow-release ceramsite of this invention possesses comprehensive properties such as lightweight, high strength, strong salt storage capacity, and good slow-release effect. On one hand, this invention mainly achieves salt storage and slow release through the combined action of temperature-sensitive agents, corrosion inhibitors, and carbonized γ-C2S. The temperature-sensitive agent molecule contains hydrophobic isopropyl groups and hydrophilic amide groups, and by embedding hydrophobic monomers in the main chain, the critical dissolution temperature (LCST) is reduced to 18-22℃. When the temperature is below the LCST, the molecular chain of the temperature-sensitive agent is in an extended state, has an affinity for the solvent, absorbs water and swells, and is internally loose, opening the channels for salt ions to enter and exit the ceramsite pores. When the temperature rises and is above the LCST, the affinity between water molecules and amide groups weakens, and the hydrophobic effect of isopropyl groups in the molecular chain strengthens and plays a dominant role, causing the molecular chains to aggregate through common hydrophobic interactions, water is discharged to form a hydrophobic layer, forming dense colloidal particles, and closing the channels for salt ions to enter and exit the ceramsite pores. This aligns perfectly with the climate of low temperatures and heavy snowfall in winter and high temperatures and heavy rainfall in summer: the low temperatures in winter open the channels to accelerate salt release, while the high temperatures in summer close the channels to store salt, making ceramsite a "smart material." The intelligent opening and closing action of the temperature-sensitive agent, the barrier and sealing effect of the CaCO3 gel after γ-C2S carbonization, and the further amplification of the slow-release function of the corrosion inhibitor work synergistically to achieve targeted, slow-release, and sustainable snow-melting performance of ceramsite. This solves the problem of excessive precipitation of unnecessary snow-melting salt and waste caused by existing salt-storing aggregates in my country's hot and rainy summers, greatly extending the service life of road materials. On the other hand, this invention mainly improves the strength of ceramsite by carbonizing γ-C2S. Ceramsite itself is not very strong, but after modification with carbonized γ-C2S, the ceramsite has high strength and high wear resistance due to its core-shell structure, which can further enhance the strength of the road surface. It will not only not be crushed, but can also slowly release salts to extend the snow-melting service life of the road surface under complex terrain, heavy traffic, and harsh weather conditions.

[0056] 2) The carbonized γ-C2S modified salt-storing slow-release ceramsite of this invention, when applied to asphalt pavement materials, can exert a long-lasting snow-melting and de-icing effect, ensuring good road performance. The snow-melting ceramsite prepared from ceramsite and carbonized γ-C2S meets the basic strength requirements for service in pavements. Furthermore, the pore-forming agent can form numerous highly interconnected pores in the shell layer, and the CaCO3 formed by carbonized γ-C2S is more porous than CaSiO3. The synergistic effect of the two is more conducive to the effective release of salts stored in the ceramsite pores under the asphalt film coating of the asphalt mixture, further enhancing the snow-melting effect.

[0057] 3) The production process of the carbonized γ-C2S modified salt-storing slow-release ceramsite of this invention is simple, and the raw materials are readily available, significantly reducing the cost of road de-icing and snow-melting operations. In particular, the main materials for preparing porous ceramsite are red mud and fly ash from industrial solid waste, which greatly promotes environmental quality improvement. The carbon sequestration behavior during the carbonization of γ-C2S is also a new form of environmental protection, promoting green living and production, and achieving green development for the whole society. Detailed Implementation

[0058] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the content of the present invention is not limited to the following embodiments.

[0059] In the following examples, the porous ceramsite used was obtained by uniformly mixing fly ash and red mud at a mass ratio of 100:70, granulating the mixture, and then sintering it at 1220℃ for 15 min. The particle size was 2.36 mm, the compressive strength was 5.6 MPa, the apparent porosity was 34%, and the apparent density was 1.38 g·cm³. -3 .

[0060] In the following examples, the γ-C2S used was obtained by ball milling steel slag and sandstone at a calcium-silicon molar ratio of 2:1, pressing the mixture into a raw material billet, drying it, and then calcining the billet at 1350°C for 3 hours, resulting in a specific surface area of ​​362 m². 2 / kg.

[0061] Example 1

[0062] A method for preparing carbonized γ-C2S modified salt-storing slow-release ceramsite includes the following steps:

[0063] 1) Add porous ceramsite, sodium tetraborate, and silane coupling agent to anhydrous ethanol at a mass ratio of 100:8:5. Let it stand and soak for 1.5 hours, then stir and soak for 3 hours at a stirring rate of 50 r / min. After taking it out, dry it at 85℃ for 1 hour to obtain active ceramsite.

[0064] 2) Sodium chloride and sodium acetate are mixed at a mass ratio of 100:30 to make snow-melting salt, and then a saturated salt solution is prepared. The active ceramic particles are soaked in the saturated salt solution at 65℃ for 24 hours. The mass ratio of active ceramic particles to snow-melting salt is 100:30. After taking them out, they are dried at 85℃ for 1 hour to obtain salt-storing ceramic particles.

[0065] 3) Dissolve the temperature-sensitive agent in anhydrous ethanol at 55℃, then add salt-accumulating ceramic particles. The mass ratio of salt-accumulating ceramic particles to temperature-sensitive agent is 100:2. The solution is then applied at a light intensity of 7 mW / cm². 2 Soaked under ultraviolet light for 4 hours, then dried at 85℃ for 1 hour to obtain salt-storage slow-release ceramsite;

[0066] The temperature-sensitive agent is obtained by reacting poly(N-isopropylacrylamide), glycidyl methacrylate, and 2,2-azobis(2-methylpropylimidazolium) in a mass ratio of 100:4:0.5 at a stirring rate of 300 r / min and a temperature of 90 °C for 1.5 h, and its low critical solution temperature (LCST) is 21 °C.

[0067] 4) Mix γ-C2S with water until homogeneous to form a γ-C2S slurry; add pore-forming agent (K12), foam stabilizer (GP), and thickener (methylcellulose) to water and stir at high speed to form a slurry with a density of 49 kg / m³. 3 The foam was poured into γ-C2S slurry and stirred at a stirring rate of 100 r / min for 50 s to obtain porous γ-C2S slurry; wherein the mass ratio of γ-C2S, water for γ-C2S slurry preparation, pore-forming agent, foam stabilizer, thickener and water for foam preparation was 100:32:0.8:2:4:12.

[0068] 5) Soak the salt-storing slow-release ceramsite in water for 4 hours and then remove it to obtain pre-wetted salt-storing slow-release ceramsite. Add the pre-wetted salt-storing slow-release ceramsite to the porous γ-C2S slurry at a mass ratio of 100:30. Stir at 100 r / min for 70 s, then cure at 20℃ for 2 days, then carbonize at 50℃, CO2 volume concentration of 80%, and relative pressure of 0.1 MPa for 4 hours. Finally, dry at 85℃ for 1 hour to obtain carbonized γ-C2S modified salt-storing slow-release ceramsite.

[0069] Example 2

[0070] A method for preparing carbonized γ-C2S modified salt-storing slow-release ceramsite includes the following steps:

[0071] 1) Add porous ceramsite, sodium dihydrogen phosphate, and zirconium aluminate coupling agent to anhydrous ethanol at a mass ratio of 100:10:5. First, let it stand and soak for 2 hours, then stir and soak for 5 hours at a stirring rate of 100 r / min. After taking it out, dry it at 90℃ for 1.5 hours to obtain active ceramsite.

[0072] 2) Sodium chloride and sodium acetate are mixed at a mass ratio of 100:45 to make snow-melting salt, and then a saturated salt solution is prepared. The activated ceramic particles are soaked in the saturated salt solution at 70℃ for 30h. The mass ratio of activated ceramic particles to snow-melting salt is 100:30. After being taken out, they are dried at 90℃ for 1.5h to obtain salt-accumulating ceramic particles.

[0073] 3) Dissolve the temperature-sensitive agent in anhydrous ethanol at 60℃, then add salt-accumulating ceramic particles. The mass ratio of salt-accumulating ceramic particles to temperature-sensitive agent is 100:8. The solution is then applied at a light intensity of 7 mW / cm². 2Soaking under ultraviolet light for 5 hours, then drying at 90℃ for 1.5 hours, yields salt-storing slow-release ceramsite.

[0074] The temperature-sensitive agent is obtained by reacting poly(N-isopropylacrylamide), glycidyl methacrylate, and 2,2-azobis(2-methylpropylimidazolium) in a mass ratio of 100:4:0.8 at a stirring rate of 300 r / min and a temperature of 80 °C for 1.8 h, and its lower critical solution temperature (LCST) is 22 °C.

[0075] 4) Mix γ-C2S with water until homogeneous to form a γ-C2S slurry; add pore-forming agent (AES), foam stabilizer (GP), and thickener (methyl hydroxyethyl cellulose) to water and stir at high speed to form a slurry with a density of 51 kg / m³. 3 The foam was poured into γ-C2S slurry and stirred at a stirring rate of 75 r / min for 50 s to obtain porous γ-C2S slurry; wherein the mass ratio of γ-C2S, water for γ-C2S slurry preparation, pore-forming agent, foam stabilizer, thickener and water for foam preparation was 100:45:3:1.5:6:16.

[0076] 5) Soak the salt-storing slow-release ceramsite in water for 4.5 hours and then remove it to obtain pre-wetted salt-storing slow-release ceramsite. Add the pre-wetted salt-storing slow-release ceramsite to the porous γ-C2S slurry at a mass ratio of 100:40. Stir at a stirring rate of 70 r / min for 90 s, then cure at 20℃ for 2 days, then carbonize at 55℃, CO2 volume concentration of 80%, and relative pressure of 0.1 MPa for 5 hours. Finally, dry at 90℃ for 1.5 hours to obtain carbonized γ-C2S modified salt-storing slow-release ceramsite.

[0077] Example 3

[0078] A method for preparing carbonized γ-C2S modified salt-storing slow-release ceramsite includes the following steps:

[0079] 1) Add porous ceramsite, sodium tripolyphosphate, and aluminate coupling agent to anhydrous ethanol at a mass ratio of 100:15:8. Let it stand and soak for 2.5 hours, then stir and soak for 3 hours at a stirring rate of 80 r / min. After taking it out, dry it at 80℃ for 1.5 hours to obtain active ceramsite.

[0080] 2) Calcium chloride and sodium acetate are mixed at a mass ratio of 100:60 to make snow-melting salt, and then a saturated salt solution is prepared. The active ceramic particles are soaked in the saturated salt solution at 75°C for 36 hours. The mass ratio of active ceramic particles to snow-melting salt is 100:45. After being taken out, they are dried at 80°C for 1.5 hours to obtain salt-accumulating ceramic particles.

[0081] 3) Dissolve the temperature-sensitive agent in anhydrous ethanol at 65℃, then add salt-accumulating ceramic particles. The mass ratio of salt-accumulating ceramic particles to temperature-sensitive agent is 100:4. The solution is then applied at a light intensity of 8 mW / cm². 2 Soaking under ultraviolet light for 5 hours, then drying at 80℃ for 1.5 hours, yields salt-storing slow-release ceramsite.

[0082] The temperature-sensitive agent is obtained by reacting poly(N-isopropylacrylamide), glycidyl methacrylate, and 2,2-azobis(2-methylpropylimidazolium) in a mass ratio of 100:6:0.5 at a stirring rate of 300 r / min and a temperature of 85 °C for 1.5 h, and its low critical solution temperature (LCST) is 18 °C.

[0083] 4) Mix γ-C2S with water until homogeneous to form a γ-C2S slurry; add pore-forming agent (AOS), foam stabilizer (GP), and thickeners (carboxymethyl cellulose and ethyl cellulose) to water and stir at high speed to form a slurry with a density of 48 kg / m³. 3 The foam was poured into γ-C2S slurry and stirred at a stirring rate of 50 r / min for 60 s to obtain porous γ-C2S slurry; wherein the mass ratio of γ-C2S, water for γ-C2S slurry preparation, pore-forming agent, foam stabilizer, thickener and water for foam preparation was 100:60:4:4:4:20.

[0084] 5) Soak the salt-storing slow-release ceramsite in water for 6 hours and then remove it to obtain pre-wetted salt-storing slow-release ceramsite. Add the pre-wetted salt-storing slow-release ceramsite to the porous γ-C2S slurry at a mass ratio of 100:50. Stir at 100 r / min for 80 s, then cure at 20℃ for 2.5 days, then carbonize at 55℃, CO2 volume concentration of 75%, and relative pressure of 0.12 MPa for 6 hours. Finally, dry at 80℃ for 1.5 hours to obtain carbonized γ-C2S modified salt-storing slow-release ceramsite.

[0085] Example 4

[0086] A method for preparing carbonized γ-C2S modified salt-storing slow-release ceramsite includes the following steps:

[0087] 1) Add porous ceramsite, corrosion inhibitor (sodium dihydrogen phosphate and sodium silicate), and organic chromium coupling agent to anhydrous ethanol at a mass ratio of 100:15:5. Let it stand and soak for 1.5 hours, then stir and soak for 4 hours at a stirring rate of 70 r / min. After taking it out, dry it at 90℃ for 2 hours to obtain active ceramsite.

[0088] 2) Mix calcium chloride and sodium acetate at a mass ratio of 100:50 to make snow-melting salt, and then prepare a saturated salt solution. Soak the activated ceramic particles in the saturated salt solution at 70℃ for 28 hours. The mass ratio of activated ceramic particles to snow-melting salt is 100:60. After taking them out, dry them at 90℃ for 2 hours to obtain salt-storing ceramic particles.

[0089] 3) Dissolve the temperature-sensitive agent in anhydrous ethanol at 55℃, then add salt-accumulating ceramic particles. The mass ratio of salt-accumulating ceramic particles to temperature-sensitive agent is 100:6. The solution is then applied at a light intensity of 8 mW / cm². 2 Soaked under ultraviolet light for 6 hours, then dried at 90℃ for 2 hours to obtain salt-storing slow-release ceramsite;

[0090] The temperature-sensitive agent is obtained by reacting poly(N-isopropylacrylamide), glycidyl methacrylate, and 2,2-azobis(2-methylpropylimidazolium) in a mass ratio of 100:6:0.7 at a stirring rate of 250 r / min and a temperature of 80 °C for 2 h, and its low critical solution temperature (LCST) is 19 °C.

[0091] 4) Mix γ-C2S with water until homogeneous to form a γ-C2S slurry; add pore-forming agent (K12 and AES), foam stabilizer (MPS), and thickener (methylcellulose and ethylcellulose) to water and stir at high speed to form a slurry with a density of 50 kg / m³. 3 The foam was poured into γ-C2S slurry and stirred at a stirring rate of 60 r / min for 60 s to obtain porous γ-C2S slurry; wherein the mass ratio of γ-C2S, water for γ-C2S slurry preparation, pore-forming agent, foam stabilizer, thickener and water for foam preparation was 100:40:6:0.8:8:12.

[0092] 5) Soak the salt-storing slow-release ceramsite in water for 5.5 hours and then remove it to obtain pre-wetted salt-storing slow-release ceramsite. Add the pre-wetted salt-storing slow-release ceramsite to the porous γ-C2S slurry at a mass ratio of 100:50. Stir at 80 r / min for 80 seconds, then cure at 25℃ for 2.5 days, then carbonize at 60℃, CO2 volume concentration of 60%, and relative pressure of 0.11 MPa for 7 hours. Finally, dry at 90℃ for 2 hours to obtain carbonized γ-C2S modified salt-storing slow-release ceramsite.

[0093] Example 5

[0094] A method for preparing carbonized γ-C2S modified salt-storing slow-release ceramsite includes the following steps:

[0095] 1) Add porous ceramsite, corrosion inhibitor (sodium tetraborate, sodium tripolyphosphate and sodium silicate), and silane coupling agent to anhydrous ethanol at a mass ratio of 100:8:8. First, let it stand and soak for 2 hours, then stir and soak for 5 hours at a stirring rate of 90 r / min. After taking it out, dry it at 90℃ for 2 hours to obtain active ceramsite.

[0096] 2) Mix calcium chloride and sodium acetate at a mass ratio of 100:40 to make snow-melting salt, and then prepare a saturated salt solution. Soak the activated ceramic particles in the saturated salt solution at 65℃ for 30 hours. The mass ratio of activated ceramic particles to snow-melting salt is 100:35. After taking them out, dry them at 90℃ for 2 hours to obtain salt-accumulating ceramic particles.

[0097] 3) Dissolve the temperature-sensitive agent in anhydrous ethanol at 60℃, then add salt-accumulating ceramic particles. The mass ratio of salt-accumulating ceramic particles to temperature-sensitive agent is 100:3. The solution is then applied at a light intensity of 9 mW / cm². 2 Soaked under ultraviolet light for 6 hours, then dried at 90℃ for 2 hours to obtain salt-storing slow-release ceramsite;

[0098] The temperature-sensitive agent is obtained by reacting poly(N-isopropylacrylamide), glycidyl methacrylate, and 2,2-azobis(2-methylpropylimidazolium) in a mass ratio of 100:5:0.6 at a stirring rate of 200 r / min and a temperature of 75°C for 2 h, and its low critical solution temperature (LCST) is 20°C.

[0099] 4) Mix γ-C2S with water until homogeneous to form a γ-C2S slurry; add pore-forming agents (AES and AOS), foam stabilizers (MPS), and thickeners (hydroxyethyl cellulose, hydroxyethyl propyl cellulose, and hydroxypropyl methyl cellulose) to water and stir at high speed to form a slurry with a density of 52 kg / m³. 3 The foam was poured into γ-C2S slurry and stirred at a stirring rate of 80 r / min for 70 s to obtain porous γ-C2S slurry; wherein the mass ratio of γ-C2S, water for γ-C2S slurry preparation, pore-forming agent, foam stabilizer, thickener and water for foam preparation was 100:50:1.2:4:4:20.

[0100] 5) Soak the salt-storing slow-release ceramsite in water for 5 hours and then remove it to obtain pre-wetted salt-storing slow-release ceramsite. Add the pre-wetted salt-storing slow-release ceramsite to the porous γ-C2S slurry with a mass ratio of 100:30. Stir at a stirring rate of 90 r / min for 90 s, then cure at 25℃ for 3 days, then carbonize at 60℃, CO2 volume concentration of 50%, and relative pressure of 0.12 MPa for 8 hours, and finally dry at 90℃ for 2 hours to obtain carbonized γ-C2S modified salt-storing slow-release ceramsite.

[0101] Comparative Example 1

[0102] The only difference between Comparative Example 1 and Example 1 is that no temperature-sensitive agent is added.

[0103] Comparative Example 2

[0104] The only difference between Comparative Example 2 and Example 1 is that: no carbonization γ-C2S modification is performed, and the salt storage slow-release ceramic particles obtained in step 3) are used as the final product.

[0105] The basic performance of the finished products obtained in each embodiment and comparative example was tested, and the results are shown in Table 1.

[0106] Table 1

[0107]

[0108]

[0109] As can be seen from Table 1, the temperature-sensitive agent is dispersed on the inner surface of the ceramsite. Therefore, the absence of a temperature-sensitive agent in Comparative Example 1 has little effect on the particle size, strength, porosity, and density of the ceramsite, and the test results are close to those of the Examples. The compressive strength of the ceramsite in Comparative Example 2 without carbonized γ-C2S modification is significantly lower than that of the salt-storage slow-release ceramsite modified with carbonized γ-C2S in the Examples, indicating that γ-C2S carbonization modification enhances the strength of the ceramsite. In addition, the porosity of the ceramsite in Comparative Example 2 is higher than that in the Examples, indicating that γ-C2S slurry can seal the pores in the ceramsite and has a moderate effect in delaying the release of snow.

[0110] Salt release performance tests were conducted on the finished products obtained in each embodiment and comparative example. The test method was as follows: 30g of the finished product was soaked in 100mL of distilled water at 10℃ or 30℃, and the chloride ion concentration in the aqueous solution was tested at 6h and 24h respectively. The chloride ion concentration was used to characterize the rate of salt release from the ceramsite. The results are shown in Table 2.

[0111] Table 2

[0112]

[0113] As shown in Table 2, the chloride ion leaching amounts at 6h and 24h in the examples were significantly lower than those in the comparative examples, indicating that the carbonized γ-C2S modified salt-storing slow-release ceramsite of the present invention has a slow and stable salt release effect. In addition, the chloride ion concentration at 30℃ in each example was lower than that at 10℃, while the chloride ion concentration at 10℃ and 30℃ in comparative example 1 was basically the same, indicating that the temperature-sensitive agent can prevent salt loss at 30℃, while allowing salt to be effectively released at 10℃. Comparative example 2, which was not modified with carbonized γ-C2S, had a significantly higher chloride ion release rate than the examples, indicating that without carbonized γ-C2S modification, the effective snow-melting components would be released and lost more quickly, making it difficult to guarantee a long-term snow-melting effect.

[0114] Application examples

[0115] The ceramsite prepared in Examples 1-5 and Comparative Examples 1-2 was used to prepare SMA-13 ​​high-viscosity, high-elasticity asphalt mixture, replacing fine aggregates with a particle size of 3-5 mm in the asphalt mixture by an equal volume. Simultaneously, two comparative examples were introduced: Comparative Example 3 did not add ceramsite or de-icing salt; Comparative Example 4 did not add ceramsite but added calcium chloride de-icing salt at a rate of 10% of the asphalt mass, added during the mixing of the asphalt mixture.

[0116] The high-viscosity, high-elasticity asphalt mixture is prepared from coarse aggregate (basalt aggregate, crushing value 8.3%), fine aggregate (basalt aggregate), filler (limestone mineral powder), fiber (polyester fiber), and high-viscosity, high-elasticity asphalt as raw materials. The specific preparation steps are as follows: the coarse aggregate and fine aggregate are weighed according to the requirements of the synthetic gradation table 3 and heated in an oven at 195℃ for 5 hours, the mold is heated at 100℃ for 1 hour, and the high-viscosity, high-elasticity asphalt is heated at 175℃ for later use; the coarse aggregate, fine aggregate, and high-viscosity, high-elasticity asphalt are added to the mixing pot in the order of coarse aggregate, fine aggregate, and high-viscosity, high-elasticity asphalt and stirred for 90 seconds, the hot filler and fiber are added and stirred for another 90 seconds until uniform; the mixture is taken out and then compacted and shaped by compaction and roller rolling at a preheated temperature of 100℃ to obtain the high-viscosity, high-elasticity asphalt mixture.

[0117] Table 3

[0118] Sieve aperture size (mm) 16 13.2 9.5 4.75 2.36 1.18 0.6 0.3 0.15 0.075 Standard gradation range (%) 100 100-90 75-50 34-20 26-15 24-14 20-12 16-10 15-9 12-8 Example 1 (%) 100.0 97.0 69.0 29.4 22.7 18.4 16.7 14.7 12.5 10.5 Example 2 (%) 100.0 96.0 69.1 29.7 22.3 19.4 16.4 14.2 12.1 10.3 Example 3 (%) 100.0 96.3 69.2 29.4 226 19.8 16.2 13.2 12.3 10.1 Example 4 (%) 100.0 96.3 69.2 29.5 22.4 19.7 16.2 14.1 12.1 10.4 Example 5 (%) 100.0 96.2 69.5 28.7 21.3 19.3 16.1 15.2 13.4 10.6 Comparative Example 1 (%) 100.0 96.3 69.4 29.4 22.0 19.4 16.1 15.0 13.2 10.5 Comparative Example 2 (%) 100.0 96.2 69.2 29.1 21.9 19.5 16.1 15.0 13.3 10.5 Comparative Example 3 (%) 100.0 96.1 69.3 29.2 22.4 19.3 16.2 15.1 13.4 10.4 Comparative Example 4 (%) 100.0 96.2 69.5 29.3 21.5 19.4 16.2 15.0 13.3 10.6

[0119] The performance indicators of the high-viscosity and high-elasticity asphalt mixtures obtained in each embodiment and comparative example are shown in Table 4.

[0120] Table 4

[0121]

[0122] Snow melting performance tests were conducted on the high-viscosity and high-elasticity asphalt mixtures obtained in each embodiment and comparative example. The test method was as follows: three rutted slab specimens with dimensions of 300mm×300mm×50mm were taken from each group, placed in a freezer at -5℃, and a layer of water was sprinkled on the surface. After freezing in the freezer for 5 hours, they were taken out and placed at 10℃ for 30 minutes. The ratio of the area of ​​the unmelted ice layer on the surface of the rutted slab to the total area of ​​the rutted slab specimen was calculated to obtain the ice coverage rate. Then, the mixture was completely thawed at 30℃. After complete thawing, water was sprinkled again and the mixture was placed in the freezer to repeat this step.

[0123] Table 5

[0124]

[0125] As can be seen from Table 5, the snow melting effect of Comparative Examples 1 and 2 decreased significantly faster than that of the Examples with increasing freeze-thaw cycles. This is because of the lack of temperature-sensitive agent and the slow-release effect of carbonized γ-C2S modification, resulting in faster loss of effective snow melting after multiple snow melting cycles. Comparative Example 3 did not add any snow melting components and had virtually no snow melting effect compared to the Examples. In Comparative Example 4, the snow melting agent was added directly to the asphalt using the traditional method without any slow-release measures, and it basically lost its snow melting effect after 30 freeze-thaw cycles. In contrast, compared to Comparative Example 4, which directly added snow melting agents using the traditional method, the Examples still maintained good snow melting capacity after multiple snow melting cycles, achieving the technical effect of long-term snow melting on the road surface.

[0126] The above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations, and any obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing carbonized γ-C2S modified salt-storing slow-release ceramsite, characterized in that, Includes the following steps: 1) Add porous ceramsite, corrosion inhibitor, and surfactant to anhydrous ethanol, let it stand and soak, then stir and soak again, remove and dry to obtain activated ceramsite; 2) Prepare a saturated salt solution from the snow-melting salt, soak the activated ceramic particles in the saturated salt solution, remove them and dry them to obtain salt-accumulating ceramic particles; 3) The temperature-sensitive agent is dissolved in heated anhydrous ethanol, and then salt-accumulating ceramic particles are added. The mixture is soaked under ultraviolet light irradiation, removed and dried to obtain salt-accumulating slow-release ceramic particles. The temperature-sensitive agent is prepared by heating poly(N-isopropylacrylamide), glycidyl methacrylate and 2,2-azobis(2-methylpropylimidazolium) to obtain the low critical dissolution temperature of 18~22℃. 4) Mix γ-C2S with water evenly to make γ-C2S slurry; add pore-forming agent, foam stabilizer and thickener to water and stir at high speed to make foam; pour the foam into γ-C2S slurry and stir evenly to obtain porous γ-C2S slurry. 5) Soak the salt-storing slow-release ceramsite in water and then remove it to obtain pre-wetted salt-storing slow-release ceramsite; add the pre-wetted salt-storing slow-release ceramsite to porous γ-C2S slurry and stir, then cure, carbonize and dry in sequence to obtain carbonized γ-C2S modified salt-storing slow-release ceramsite.

2. The preparation method of carbonized γ-C2S modified salt-storing slow-release ceramsite according to claim 1, characterized in that, The porous ceramsite is formed by granulation and sintering of fly ash and red mud; the porous ceramsite has a particle size of 2.36~4.75mm, a compressive strength ≥5.0MPa, an apparent porosity ≥30%, and an apparent density ≤1.4g·cm³. -3 .

3. The preparation method of carbonized γ-C2S modified salt-storing slow-release ceramsite according to claim 1, characterized in that, The corrosion inhibitor is one or more of sodium tetraborate, sodium dihydrogen phosphate, sodium tripolyphosphate, and sodium silicate; the surfactant is one of silane coupling agent, aluminate coupling agent, zirconate aluminate coupling agent, and organochromium coupling agent; the mass ratio of porous ceramic particles, corrosion inhibitor, and surfactant is 100:(8~15):(5~8).

4. The preparation method of carbonized γ-C2S modified salt-storing slow-release ceramsite according to claim 1, characterized in that, The snow-melting salt is a mixture of chloride salt and sodium acetate; the mass ratio of the active ceramsite to the snow-melting salt is 100:(30~60).

5. The preparation method of carbonized γ-C2S modified salt-storing slow-release ceramsite according to claim 1, characterized in that, The mass ratio of the salt-storing ceramic particles to the temperature-sensitive agent is 100:(2~8).

6. The preparation method of carbonized γ-C2S modified salt-storing slow-release ceramsite according to claim 1, characterized in that, The γ-C2S is obtained by ball milling steel slag and sandstone at a calcium-silicon molar ratio of 2:1, pressing the mixture into a raw material blank, and then drying and calcining it, with a specific surface area ≥300 m². 2 / kg.

7. The method for preparing carbonized γ-C2S modified salt-storing slow-release ceramsite according to claim 1, characterized in that, The pore-forming agent is one or two of sodium dodecyl sulfate, sodium fatty alcohol polyoxyethylene ether sulfate, and sodium α-alkenyl sulfonate; the foam stabilizer is one of trihydroxyoxyolefin polyether and silicone resin polyether emulsion; and the thickener is one or more of methylcellulose, methyl hydroxyethylcellulose, carboxymethylcellulose, ethylcellulose, hydroxyethylcellulose, hydroxyethylpropylcellulose, and hydroxypropyl methylcellulose.

8. The method for preparing carbonized γ-C2S modified salt-storing slow-release ceramsite according to claim 1, characterized in that, The mass ratio of the salt-storing slow-release ceramsite to the porous γ-C2S slurry is 100:(30~50); the curing temperature is 20~25℃, and the curing time is 2~3 days; the carbonization conditions are: temperature 50~60℃, CO2 volume concentration 50~80%, relative pressure 0.1~0.12MPa, and carbonization time 4~8h.

9. A carbonized γ-C2S modified salt-storing slow-release ceramsite prepared by the method according to any one of claims 1 to 8, characterized in that, The carbonized γ-C2S modified salt-storing slow-release ceramsite has a particle size of 3-5 mm, a compressive strength ≥7.5 MPa, an apparent porosity of 20-30%, and an apparent density ≤1.5 g·cm³. -3 .

10. The application of carbonized γ-C2S modified salt-storing slow-release ceramsite prepared by any one of claims 1 to 8 in asphalt pavement materials.

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