Water-erodible reinforced recycled asphalt concrete and method of making same
Patent Information
- Application Number
- CN202611117103.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-27
- Publication Date
- 2026-09-25
AI Technical Summary
然而，上述方法仍存在明显不足：抗剥落剂多依赖表面吸附作用，长期水环境下易发生迁移或失效；偶联剂通常仅形成单分子层结构，界面结构稳定性有限；聚合物改性主要作用于沥青相，对集料界面调控能力不足，难以从根本上改善界面结构
（1）本发明通过氢氧化钙与硅酸钠在集料表面原位生成C-S-H凝胶结构或硅酸钙水化产物，构建具有微纳孔隙的矿化骨架层，使界面由传统的物理包裹型结合转变为结构嵌锁型结合，显著提高界面机械咬合能力与稳定性。
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Figure CN122809792A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of road engineering materials technology, specifically to a water-erosion-resistant reinforced recycled asphalt concrete and its preparation method. Background Technology
[0002] As one of the most commonly used pavement materials in road engineering, the long-term service performance of asphalt concrete largely depends on the interfacial adhesion between asphalt and aggregates and its stability in aquatic environments. In actual use, pavement structures are exposed to complex environments such as rainfall, groundwater infiltration, and de-icing agents. Moisture easily penetrates along the asphalt-aggregate interface, leading to a decrease in interfacial adhesion and subsequently causing typical water damage diseases such as stripping, loosening, and potholes, seriously affecting the durability and service life of the pavement structure.
[0003] With the increasing demand for road maintenance and resource recycling, the application ratio of recycled asphalt pavement (RAP) is gradually increasing. However, the old asphalt in RAP usually undergoes long-term oxidative aging, resulting in a reduction in its lightweight components and changes in its polar structure. This reduces the interfacial compatibility between asphalt and new and old aggregates in the recycled asphalt concrete system, making the interfacial structure more fragile and further exacerbating the problem of insufficient water stability.
[0004] To address the water damage problem in asphalt concrete, existing technologies mainly employ anti-stripping agents, coupling agents, or polymer modification. For example, amine-based anti-stripping agents or silane coupling agents are used to chemically treat the aggregate surface to enhance the chemical bonding between asphalt and aggregate; or polymers such as SBS and polyolefins are added to modify the asphalt to improve its mechanical properties and water resistance. However, these methods still have significant shortcomings: anti-stripping agents largely rely on surface adsorption, making them prone to migration or failure in long-term water environments; coupling agents typically form only a monolayer structure, resulting in limited interfacial stability; and polymer modification primarily acts on the asphalt phase, lacking sufficient ability to regulate the aggregate interface and failing to fundamentally improve the interfacial structure.
[0005] Therefore, existing technologies generally struggle to achieve a synergistic balance between enhanced interfacial adhesion, improved structural stability, and guaranteed long-term durability under complex aquatic conditions. How to construct a novel interfacial control system with stable structural characteristics that can effectively block moisture intrusion pathways and significantly enhance the interaction between asphalt and aggregates has become a pressing technical problem to be solved in this field. Summary of the Invention
[0006] The purpose of this invention is to provide a water-resistant reinforced recycled asphalt concrete and its preparation method, thereby improving the water stability of recycled asphalt concrete.
[0007] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a water-resistant polar polyolefin interface-reinforced recycled asphalt concrete, wherein the raw materials for preparing the recycled asphalt concrete are as follows, by weight parts: 55-65 parts new aggregate, 11-26 parts recycled asphalt pavement material RAP, 3.5-5 parts base asphalt, 4-8 parts mineral powder, and 1.25-3.7 parts interface reinforcement component; The interface-enhancing component comprises 0.3–0.8 parts calcium hydroxide, 0.2–0.6 parts sodium silicate, 0.2–0.6 parts polar polyolefin, 0.05–0.2 parts interface modifier, and 0.5–1.5 parts water.
[0008] Preferably, the new aggregate is one of basalt, limestone or diabase, and the particle size of the new aggregate is divided into four grades: 1-3 mm, 3-5 mm, 5-10 mm and 10-16 mm. The recycled asphalt pavement material (RAP) comprises old asphalt and old aggregate, wherein the old asphalt content is 4% to 5%. The old asphalt is one of base asphalt or SBS modified asphalt; The old aggregate is one of basalt crushed stone and limestone crushed stone; The recycled asphalt pavement material RAP is sieved into 1 3mm, 3 5mm, 5 10mm, 10 16mm four-size particle size; The base asphalt is road petroleum asphalt with a penetration grade of 70# or 90#. The mineral powder is limestone mineral powder.
[0009] Preferably, the amount of the recycled asphalt pavement material RAP is 20%-40% of the mass of the new aggregate.
[0010] Preferably, the polar polyolefin is one of oxidized polyethylene and maleic anhydride-grafted polypropylene; Preferably, the oxidized polyethylene has a melt index of 5–25 g / 10 min and an oxidation degree of 1%–5%. The grafting rate of the maleic anhydride-grafted polypropylene is 0.5% to 2.5%.
[0011] Preferably, the interface modifier is one of fatty acid salts, rosin salts, or light oils.
[0012] Preferably, the interface modifier is sodium stearate or sodium rosinate; the interface modifier is used in the form of an aqueous solution with a mass concentration of 0.5% to 5%.
[0013] Preferably, the raw materials for preparing the recycled asphalt concrete are as follows, based on parts by weight: The mixture consists of 60 parts of new aggregate, 18 parts of recycled asphalt pavement material RAP, 4.2 parts of base asphalt, 5.5 parts of mineral powder, and 2.8 parts of interface reinforcement components. The interface-enhancing component comprises 0.6 parts calcium hydroxide, 0.5 parts sodium silicate, 0.6 parts polar polyolefin, 0.1 parts interface modifier, and 1.0 part water; The new aggregate is basalt, and the particle size of the new aggregate is divided into four grades: 1-3 mm, 3-5 mm, 5-10 mm and 10-16 mm. The polar polyolefin is oxidized polyethylene, which has a melt index of 15 g / 10 min and an oxidation degree of 2.5%. The base asphalt is No. 70 road petroleum asphalt, and the mineral powder is limestone mineral powder; The interface modifier is sodium stearate, which is added in the form of an aqueous solution with a mass concentration of 0.5%.
[0014] Secondly, the present invention provides a method for preparing the above-mentioned water-erosion-resistant polar polyolefin interface-reinforced recycled asphalt concrete, the preparation method comprising the following steps: (1) Dry RAP and new aggregate at 100-120℃ for 2-4 h to obtain mixed aggregate A; (2) Dissolve calcium hydroxide and sodium silicate in water to form a mineralization reaction solution, add polar polyolefin and stir to form a suspension dispersion system; (3) Spray the suspended dispersion system onto the surface of the mixed aggregate, so that the surface moisture content of the aggregate is controlled at 2% to 5%; (4) The mixture was kept at 80-100℃ for 30-90 min to obtain the interface-enhanced aggregate B; (5) Add an interface modifier to the surface of the aggregate after the interface enhancement treatment and spray it a second time to form a hydrophobic control layer on the outer layer of the interface to obtain mixed aggregate C. (6) Heat the base asphalt to 150-165°C and mix it with the aggregate and mineral powder obtained in step (5), wherein dry mixing takes 30-60 seconds and wet mixing takes 90-120 seconds to obtain asphalt mixture; (7) The asphalt mixture is compacted at 165-175°C to obtain water-resistant polar polyolefin interface-reinforced recycled asphalt concrete.
[0015] Preferably, the preparation method includes the following steps: (1) After mixing recycled asphalt pavement material RAP with new aggregate, it is dried at 110℃ for 3 h to obtain mixed aggregate A; (2) Dissolve 0.6 parts of calcium hydroxide and 0.5 parts of sodium silicate in 1.0 parts of water to form a mineralization reaction solution. Then add 0.6 parts of oxidized polyethylene and stir for 15 min at 300 r / min to form a suspension dispersion system and obtain mixture A. (3) Spray the mixture A onto the surface of the aggregate A, so that the surface moisture content of the aggregate is controlled at 3% to 4%, and then keep it at 90℃ for 45 min to obtain the aggregate B; (4) Spray a 0.5% sodium stearate aqueous solution onto the surface of the mixed aggregate B and stir for 10 min to form a hydrophobic control layer on the outer layer of the interface, thus obtaining the mixed aggregate C. (5) Heat the No. 70 road petroleum asphalt to 160°C, add mixed aggregate C and limestone mineral powder and mix, including dry mixing for 45 s and wet mixing for 100 s, to obtain asphalt mixture; (6) The asphalt mixture is compacted at 170°C to obtain water-resistant polar polyolefin interface-reinforced recycled asphalt concrete.
[0016] The beneficial effects of this invention are as follows: (1) The present invention generates CSH gel structure or calcium silicate hydration products in situ on the surface of aggregates by calcium hydroxide and sodium silicate, and constructs a mineralized skeleton layer with micro-nano pores, so that the interface changes from the traditional physical encapsulation type bonding to the structural interlocking type bonding, which significantly improves the mechanical interlocking ability and stability of the interface.
[0017] (2) By introducing polar polyolefins and embedding them into the pore structure of mineralized products or adsorbing them on their surface, the synergistic reinforcement effect of inorganic mineralized phase and organic polymer is achieved, so that the interface layer has both rigid support and flexible bridging characteristics, thereby improving the adhesion strength and anti-peeling ability between asphalt and aggregate.
[0018] (3) By introducing sodium stearate into the outer layer of the composite interface to form a hydrophobic control layer, the interface forms a gradient wetting structure, effectively blocking the water intrusion path along the interface, significantly reducing the risk of water-induced damage, and improving the structural stability of the material under immersion and freeze-thaw cycle conditions.
[0019] (4) The present invention adopts an integrated process of spraying-in-situ mineralization-asphalt mixing. The process is simple and highly operable. It is compatible with existing asphalt mixture production equipment and is suitable for high RAP content recycled asphalt systems. It has good engineering application prospects.
[0020] (5) Performance test results show that the freeze-thaw splitting tensile strength ratio (TSR) of the recycled asphalt concrete prepared by the present invention is not less than 89%, and the residual stability (RMS) after immersion is not less than 92%, which is significantly better than conventional anti-stripping agents or single polymer modification systems, indicating that it has a significant improvement effect in water stability and durability.
[0021] In summary, this invention achieves simultaneous improvement in the water erosion resistance and interface stability of recycled asphalt concrete through multi-scale interface structure synergistic regulation, demonstrating significant technological advancement and engineering application value. Attached Figure Description
[0022] Figure 1 This is a schematic diagram of a method for preparing water-resistant polar polyolefin interface-reinforced recycled asphalt concrete. Figure 2 This is a bar chart showing the splitting tensile strength ratio of concrete in different embodiments and comparative examples; Figure 3 This is a bar chart showing the residual stability of concrete after immersion in water in different embodiments and comparative examples. Detailed Implementation
[0023] To make the objectives, technical solutions, and beneficial effects of this invention clearer, the invention will be further described below with reference to specific embodiments, but the scope of protection of this invention is not limited thereto.
[0024] The relevant properties of the matrix asphalt involved in this invention are shown in Table 1.
[0025] Table 1 Basic performance indicators of base asphalt
[0026] Example 1 A method for preparing a water-erosion-resistant polar polyolefin interface-reinforced recycled asphalt concrete a includes the following steps: (1) Raw material ratio By weight: 60 parts new aggregate, 18 parts recycled asphalt pavement material RAP (accounting for 30% of the weight of new aggregate), 4.2 parts base asphalt, 5.5 parts mineral powder, and 2.4 parts interface reinforcement component; The interface-enhancing components include: 0.5 parts calcium hydroxide, 0.4 parts sodium silicate, 0.4 parts polar polyolefin, 0.1 parts interface modifier, and 1.0 part water; The new aggregate is basalt, with particle sizes of 1–3 mm, 3–5 mm, 5–10 mm and 10–16 mm. The recycled asphalt pavement material is composed of old asphalt and old aggregate, wherein the old asphalt content is 4%, the old asphalt is the base asphalt, and the old aggregate is basalt crushed stone. The base asphalt is No. 70 road petroleum asphalt; The mineral powder is limestone mineral powder (particle size less than 0.075 mm); The polar polyolefin is oxidized polyethylene, with a melt index of 15 g / 10 min and an oxidation degree of 2.5%. The interface modifier is sodium stearate.
[0027] (2) Aggregate pretreatment After mixing RAP with new aggregate, the mixture was dried at 110°C for 3 hours to obtain mixed aggregate A.
[0028] (3) Preparation of mineralization reaction solution Calcium hydroxide and sodium silicate are dissolved in water to form a mineralization reaction solution. Then, a polar polyolefin is added, and a uniform suspension dispersion system is formed under stirring conditions (300 r / min, 15 min) to obtain mixture A.
[0029] (4) Interface spraying and reaction Mixture A is sprayed onto the surface of the mixed aggregate and kept at 90°C for 45 min to allow calcium hydroxide and sodium silicate to undergo a mineralization reaction, generating calcium silicate hydration products on the surface of the aggregate. At the same time, polar polyolefin particles are deposited and embedded in the pores of the mineralized structure to form a composite interface layer, resulting in mixed aggregate B. (5) Interface adjustment processing Add an interface modifier (0.5% sodium stearate solution), spray twice and stir for 10 min to form a hydrophobic control layer on the outer layer of the interface, and obtain mixed aggregate C; (6) Asphalt mixing The base asphalt is heated to 160°C, and the treated mixed aggregate C and mineral powder are added and mixed. The mixture is dry-mixed for 45 seconds and wet-mixed for 100 seconds to ensure that the asphalt evenly coats the mixed aggregate C, thus obtaining the mixture. (7) Molding The mixture was compacted at 170°C to obtain reinforced recycled asphalt concrete a.
[0030] A schematic diagram of the preparation method is shown below. Figure 1 As shown.
[0031] Example 2 A water-erosion-resistant polar polyolefin interface-reinforced recycled asphalt concrete b The difference from Example 1 is that: The interface enhancement component consists of 2.8 parts, of which: 0.6 parts calcium hydroxide, 0.5 parts sodium silicate, 0.6 parts polar polyolefin (oxidized polyethylene), 0.1 parts interface modifier (0.5% sodium stearate solution), and 1.0 part water.
[0032] Example 3 A water-erosion-resistant polar polyolefin interface-reinforced recycled asphalt concrete c The difference from Example 1 is that: The interface enhancement component consists of 1.65 parts, of which: 0.4 parts calcium hydroxide, 0.3 parts sodium silicate, 0.3 parts polar polyolefin (oxidized polyethylene), 0.05 parts interface modifier (1% sodium stearate solution), and 0.6 parts water.
[0033] Example 4 A water-erosion-resistant polar polyolefin interface-reinforced recycled asphalt concrete The difference from Example 1 is that: By weight: 55 parts new aggregate, 11 parts RAP, 3.5 parts base bitumen, 4 parts mineral powder, and 1.25 parts interface reinforcement component; RAP accounts for 20% of the mass of new aggregates.
[0034] The interface-enhancing component includes: 0.3 parts calcium hydroxide, 0.2 parts sodium silicate, 0.2 parts polar polyolefin, 0.05 parts interface modifier, and 0.5 parts water.
[0035] The polar polyolefin is oxidized polyethylene with a melt index of 5 g / 10 min and an oxidation degree of 1%; the interface modifier is sodium stearate.
[0036] In the preparation method: RAP and new aggregates were dried at 100℃ for 2 hours; mineralization reaction liquid was sprayed onto the surface of aggregates to control the surface moisture content at 2%; then the reaction was kept at 80℃ for 30 min; the base asphalt was heated to 150℃ and mixed, including dry mixing for 30 s and wet mixing for 90 s; finally, it was compacted at 165℃ to obtain recycled asphalt concrete d.
[0037] Example 5 A water-erosion-resistant polar polyolefin interface-reinforced recycled asphalt concrete The difference from Example 1 is that: By weight: 65 parts new aggregate, 26 parts RAP, 5 parts matrix bitumen, 8 parts mineral powder, and 3.7 parts interface reinforcement component; Of these, RAP accounts for 40% of the new aggregate mass.
[0038] The interface-enhancing component includes: 0.8 parts calcium hydroxide, 0.6 parts sodium silicate, 0.6 parts polar polyolefin, 0.2 parts interface modifier, and 1.5 parts water.
[0039] The polar polyolefin is oxidized polyethylene with a melt index of 25 g / 10 min and an oxidation degree of 5%; the interface modifier is an aqueous solution of sodium stearate.
[0040] In the preparation method: RAP and new aggregates were dried at 120℃ for 4 hours; mineralization reaction liquid was sprayed onto the surface of the aggregates to control the surface moisture content at 5%; then the reaction was kept at 100℃ for 90 min; the base asphalt was heated to 165℃ and mixed, including 60 s of dry mixing and 120 s of wet mixing; finally, it was compacted at 175℃ to obtain recycled asphalt concrete e.
[0041] Example 6 A water-erosion-resistant polar polyolefin interface-reinforced recycled asphalt concrete The difference from Example 1 is that: The polar polyolefin was replaced with maleic anhydride-grafted polypropylene, with a grafting rate of 0.5%.
[0042] The proportions of the remaining raw materials and the preparation process are the same as in Example 1, resulting in recycled asphalt concrete f.
[0043] Example 7 A water-erosion-resistant polar polyolefin interface-reinforced recycled asphalt concrete g The difference from Example 1 is that: The polar polyolefin is maleic anhydride-grafted polypropylene with a grafting rate of 2.5%.
[0044] The proportions of the remaining raw materials and the preparation process are the same as in Example 1, resulting in g of recycled asphalt concrete.
[0045] Example 8 A water-erosion-resistant polar polyolefin interface-reinforced recycled asphalt concrete h The difference from Example 1 is that: The base asphalt was replaced with No. 90 road petroleum asphalt, and the amount of base asphalt used was 4.5 parts.
[0046] The remaining raw materials and preparation process are the same as in Example 1, resulting in recycled asphalt concrete h.
[0047] Example 9 A water-erosion-resistant polar polyolefin interface-reinforced recycled asphalt concrete The difference from Example 1 is that: The new aggregate is diabase, and the particle size is still divided into four grades: 1–3 mm, 3–5 mm, 5–10 mm and 10–16 mm. The proportions of the remaining raw materials and the preparation process are the same as in Example 1, resulting in recycled asphalt concrete i.
[0048] Comparative Example 1 The difference from Example 1 is that: No interface-enhancing components are added; all other materials and preparation processes are exactly the same.
[0049] Comparative Example 2 The difference from Example 1 is that no polar polyolefin is added to the interface reinforcement component; it only contains calcium hydroxide, sodium silicate, and water, while the other conditions are the same as in Example 1.
[0050] Comparative Example 3 The difference from Example 1 is that calcium hydroxide and sodium silicate are not added; only polar polyolefins are added to the asphalt for conventional modification treatment, and the other conditions are the same as in Example 1.
[0051] Comparative Example 4 The difference from Example 1 is that 0.4 parts of an amine anti-stripping agent were used to replace the interface reinforcement component, while the other conditions were the same as in Example 1.
[0052] Comparative Example 5 The difference from Example 1 is that the aggregate surface spraying and mineralization reaction steps are not performed; asphalt mixing is carried out directly, and the other conditions are the same as in Example 1.
[0053] Experiment 1 According to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG 3410-2025), the residual stability (RMS) and splitting tensile strength ratio (TSR) of Examples 1-3 and Comparative Examples 1-5 were determined by immersion Marshall test and freeze-thaw splitting test. The results are as follows: Figure 2 and Figure 3 As shown.
[0054] Figure 2 The results showed significant differences in the freeze-thaw splitting tensile strength ratio (TSR) among the different embodiments and comparative examples. The TSRs of Examples 1, 2, and 3 were 86.3%, 89.7%, and 84.1%, respectively, all higher than those of Comparative Examples 1-5. This indicates that the present invention, through the treatment with interface reinforcing components, can effectively improve the water stability and resistance to freeze-thaw water damage of recycled asphalt concrete.
[0055] Among them, Example 2 showed the highest TSR at 89.7%, indicating that under higher dosage of the interface reinforcement component, the synergistic effect between calcium hydroxide, sodium silicate, and polar polyolefin was more complete, forming a more stable mineralized-polyolefin composite interface layer on the aggregate surface, thereby enhancing the adhesion between asphalt and aggregate. Example 1 had a TSR of 86.3%, also exhibiting good resistance to water damage; Example 3 had a TSR of 84.1%, which, although lower than Examples 1 and 2, was still significantly better than the comparative examples, indicating that the present invention can still exert an interface reinforcement effect under lower dosage conditions.
[0056] The TSRs of Comparative Examples 1-5 were 75.6%, 81.2%, 79.8%, 82.6%, and 73.9%, respectively. Comparative Example 5 had the lowest TSR at 73.9%, indicating that without effective interface treatment, the asphalt-aggregate interface is easily eroded by moisture and delaminates. Comparative Examples 2 and 3 had TSRs of 81.2% and 79.8%, respectively, showing that neither the mineralization system alone nor the polar polyolefin modification alone could achieve the effect of the composite interface reinforcement system of this invention. The TSR of Comparative Example 4 was 82.6%, higher than some of the comparative examples, but still lower than Examples 1-3, indicating that conventional anti-stripping agents have limited effect on improving water stability.
[0057] In summary, the TSR of Examples 1 to 3 of the present invention remained above 84%, which was significantly better than that of the comparative examples that did not use the interface reinforcement system of the present invention. This proves that the present invention can significantly improve the interface stability and water erosion resistance of recycled asphalt concrete under freeze-thaw damage conditions.
[0058] Figure 3 The results showed that the residual stability (RMS) of immersion water in Examples 1, 2 and 3 were 89.6%, 92.8% and 87.4% respectively, which were significantly higher than those in Comparative Examples 1 to 5. This indicates that the polar polyolefin interface-reinforced recycled asphalt concrete prepared by the present invention has better resistance to water damage and water stability.
[0059] Among them, Example 2 showed the highest RMS at 92.8%, indicating that under higher interfacial reinforcement component dosage, the mineralization products formed by calcium hydroxide and sodium silicate were more complete, and the polar polyolefin could be more effectively embedded in the mineralized pores to form a composite interfacial layer, thereby significantly enhancing the adhesion between asphalt and aggregate. Example 1 had an RMS of 89.6%, also exhibiting good water stability; Example 3 had an RMS of 87.4%, which, although lower than Example 1 and Example 2, was still higher than all comparative examples, indicating that the present invention can still play an effective interfacial reinforcement role under lower dosage conditions.
[0060] The RMS values of Comparative Examples 1-5 were 78.2%, 84.5%, 82.7%, 85.3%, and 76.8%, respectively. Comparative Example 5 had the lowest RMS value at only 76.8%, indicating that without effective interfacial reinforcement treatment, recycled asphalt concrete is prone to decreased interfacial adhesion and water damage under immersion conditions. Comparative Examples 2 and 3 had RMS values of 84.5% and 82.7%, respectively, showing that using a mineralization system alone or modifying with polar polyolefins alone can improve water stability to some extent, but the improvement is limited and cannot achieve the synergistic effect of the mineralization reaction and polar polyolefins of this invention. The RMS value of Comparative Example 4 was 85.3%, indicating that although conventional anti-stripping agents can improve the water damage resistance of asphalt concrete, it is still lower than that of Examples 1-3 of this invention.
[0061] In summary, the RMS of Examples 1-3 all remained above 87%, which was significantly better than that of the comparative examples. This proves that the present invention can effectively enhance the adhesion between asphalt and aggregate, inhibit water intrusion and interface delamination, and thus significantly improve the water immersion stability of recycled asphalt concrete by constructing a composite interface layer on the aggregate surface with the synergistic effect of mineralized products and polar polyolefins.
[0062] In summary, the present invention provides a mineralization and polyolefin synergistic interface-reinforced recycled asphalt concrete and its preparation method. This system constructs a mineralization reaction layer on the aggregate surface and introduces polar polyolefins to form a flexible transition interface, transforming the asphalt-aggregate interface from a traditional single physical adhesion to a composite interface structure. Specifically, the mineralization reaction generates a dense, rough inorganic structural layer on the aggregate surface, improving the interfacial mechanical interlocking ability, while the polar polyolefins enhance the compatibility with asphalt and the mineralization layer through their polar groups, forming a stable transition layer. The synergistic effect of both effectively blocks water intrusion pathways and improves the interfacial anti-peeling ability, thereby significantly enhancing the water stability of asphalt concrete and demonstrating promising engineering application prospects.
[0063] Experiment 2 To further evaluate the interfacial adhesion between asphalt and aggregate under water action, a boiling water stripping test was conducted. The treated aggregates (Example 2 and Comparative Examples 1-5) were mixed with asphalt to prepare coated aggregate samples, which were then placed in boiling water for 30 min. After cooling, the asphalt film stripping was observed, and the stripping area ratio was calculated. The results are shown in Table 2.
[0064] Table 2. Percentage of Asphalt Film Stripping Area in Different Groups
[0065] As shown in Table 2, the asphalt film peeling area ratio of Example 2 is only 4.6%, significantly lower than that of Comparative Examples 1-5. Although Comparative Example 2 forms certain mineralized products, it lacks the flexible bridging and interfacial compatibility of polar polyolefins, and its peeling area still reaches 14.8%. Although Comparative Example 3 uses polar polyolefin modification, it does not form a mineralized interlocking structure on the aggregate surface, and its peeling area is 16.2%. The peeling area of Example 2 is significantly lower than the other two, indicating that the mineralized-polyolefin composite interface layer formed by the present invention can significantly improve the asphalt film's retention capacity in an aqueous environment.
[0066] Experimental Test 3 Long-term immersion and acid / alkali / salt corrosion test To simulate the complex water environment in actual road service, the specimens prepared in Example 2, Comparative Example 2, Comparative Example 3 and Comparative Example 4 were immersed in deionized water, 3% sodium chloride solution, pH=4 acidic solution and pH=10 alkaline solution for 7 days, respectively. The residual stability after immersion was then measured, and the results are shown in Table 3.
[0067] Table 3 Residual stability under different water environments
[0068] As shown in Table 3, Example 2 maintained high residual stability under water, salt, acid, and alkaline environments, significantly higher than Comparative Examples 2-4. This indicates that conventional anti-stripping agents or single mineralization / single polyolefin systems are prone to interfacial degradation in complex aquatic environments, while the composite interfacial layer constructed in this invention exhibits better environmental stability and erosion resistance.
[0069] Experiment 4 Stability test of multiple freeze-thaw cycles To evaluate the durability of the present invention under repeated freeze-thaw conditions, Example 2, Comparative Example 1, Comparative Example 2, Comparative Example 3 and Comparative Example 4 were subjected to three freeze-thaw cycles, and the splitting tensile strength ratio after the cycles was measured. The results are shown in Table 4.
[0070] Table 4. TSR results after multiple freeze-thaw cycles
[0071] As shown in Table 4, after three freeze-thaw cycles, the TSR of Example 2 remained at 84.6%, with a retention rate of 94.3%, which is significantly higher than that of the other comparative examples. This result indicates that the present invention not only improves the interfacial adhesion performance in the initial state, but also maintains the stability of the interfacial structure under repeated water-ice phase transitions, demonstrating excellent long-term resistance to freeze-thaw water damage.
[0072] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. A water-erosion-resistant polar polyolefin interface-reinforced recycled asphalt concrete, characterized in that, The raw materials for preparing the recycled asphalt concrete, by weight, are as follows: 55-65 parts new aggregate, 11-26 parts recycled asphalt pavement material RAP, 3.5-5 parts base asphalt, 4-8 parts mineral powder, and 1.25-3.7 parts interface reinforcement component; The interface-enhancing component comprises 0.3–0.8 parts calcium hydroxide, 0.2–0.6 parts sodium silicate, 0.2–0.6 parts polar polyolefin, 0.05–0.2 parts interface modifier, and 0.5–1.5 parts water.
2. The recycled asphalt concrete according to claim 1, characterized in that, The new aggregate is one of basalt, limestone or diabase, and the particle size of the new aggregate is divided into four grades: 1-3 mm, 3-5 mm, 5-10 mm and 10-16 mm. The recycled asphalt pavement material (RAP) comprises old asphalt and old aggregate, wherein the old asphalt content is 4% to 5%. The old asphalt is one of base asphalt or SBS modified asphalt; The old aggregate is one of basalt crushed stone and limestone crushed stone; The recycled asphalt pavement material RAP is sieved into 1 3mm, 3 5mm, 5 10mm, 10 16mm four-size particle size; The base asphalt is road petroleum asphalt with a penetration grade of 70# or 90#. The mineral powder is limestone mineral powder.
3. The recycled asphalt concrete according to claim 2, characterized in that, The amount of the recycled asphalt pavement material RAP is 20%-40% of the mass of the new aggregate.
4. The recycled asphalt concrete according to claim 3, characterized in that, The polar polyolefin is one of oxidized polyethylene and maleic anhydride-grafted polypropylene.
5. The recycled asphalt concrete according to claim 4, characterized in that, The oxidized polyethylene has a melt index of 5–25 g / 10 min and an oxidation degree of 1%–5%. The grafting rate of the maleic anhydride-grafted polypropylene is 0.5% to 2.5%.
6. The recycled asphalt concrete according to claim 5, characterized in that, The interface modifier is one of fatty acid salts, rosin salts, or light oils.
7. The recycled asphalt concrete according to claim 6, characterized in that, The interface modifier is sodium stearate or sodium rosinate; the interface modifier is used in the form of an aqueous solution with a mass concentration of 0.5% to 5%.
8. The recycled asphalt concrete according to claim 7, characterized in that, The raw materials for preparing the recycled asphalt concrete, by weight, are as follows: The mixture consists of 60 parts of new aggregate, 18 parts of recycled asphalt pavement material RAP, 4.2 parts of base asphalt, 5.5 parts of mineral powder, and 2.8 parts of interface reinforcement components. The interface-enhancing component comprises 0.6 parts calcium hydroxide, 0.5 parts sodium silicate, 0.6 parts polar polyolefin, 0.1 parts interface modifier, and 1.0 part water; The new aggregate is basalt, and the particle size of the new aggregate is divided into four grades: 1-3 mm, 3-5 mm, 5-10 mm and 10-16 mm. The polar polyolefin is oxidized polyethylene, which has a melt index of 15 g / 10 min and an oxidation degree of 2.5%. The base asphalt is No. 70 road petroleum asphalt, and the mineral powder is limestone mineral powder; The interface modifier is sodium stearate, which is added in the form of an aqueous solution with a mass concentration of 0.5%.
9. A method for preparing water-erosion-resistant polar polyolefin interface-reinforced recycled asphalt concrete according to any one of claims 1 to 8, characterized in that, The preparation method includes the following steps: (1) Dry RAP and new aggregate at 100-120℃ for 2-4 h to obtain mixed aggregate A; (2) Dissolve calcium hydroxide and sodium silicate in water to form a mineralization reaction solution, add polar polyolefin and stir to form a suspension dispersion system; (3) Spray the suspended dispersion system onto the surface of the mixed aggregate, so that the surface moisture content of the aggregate is controlled at 2% to 5%; (4) The mixture was kept at 80-100℃ for 30-90 min to obtain the interface-enhanced aggregate B; (5) Add an interface modifier to the surface of the aggregate after the interface enhancement treatment and spray it a second time to form a hydrophobic control layer on the outer layer of the interface to obtain mixed aggregate C. (6) Heat the base asphalt to 150-165°C and mix it with the aggregate and mineral powder obtained in step (5), wherein dry mixing takes 30-60 seconds and wet mixing takes 90-120 seconds to obtain asphalt mixture; (7) The asphalt mixture is compacted at 165-175°C to obtain water-resistant polar polyolefin interface-reinforced recycled asphalt concrete.
10. The preparation method according to claim 9, characterized in that, The preparation method includes the following steps: (1) After mixing recycled asphalt pavement material RAP with new aggregate, it is dried at 110℃ for 3 h to obtain mixed aggregate A; (2) Dissolve 0.6 parts of calcium hydroxide and 0.5 parts of sodium silicate in 1.0 parts of water to form a mineralization reaction solution. Then add 0.6 parts of oxidized polyethylene and stir for 15 min at 300 r / min to form a suspension dispersion system and obtain mixture A. (3) Spray the mixture A onto the surface of the aggregate A, so that the surface moisture content of the aggregate is controlled at 3% to 4%, and then keep it at 90℃ for 45 min to obtain the aggregate B; (4) Spray a 0.5% sodium stearate aqueous solution onto the surface of the mixed aggregate B and stir for 10 min to form a hydrophobic control layer on the outer layer of the interface, thus obtaining the mixed aggregate C. (5) Heat the No. 70 road petroleum asphalt to 160°C, add mixed aggregate C and limestone mineral powder and mix, including dry mixing for 45 s and wet mixing for 100 s, to obtain asphalt mixture; (6) The asphalt mixture is compacted at 170°C to obtain water-resistant polar polyolefin interface-reinforced recycled asphalt concrete.