A semi-flexible pavement with heat reflection and high thermal conductivity and its construction method

Abstract

This invention discloses a semi-flexible pavement with heat reflection and high thermal conductivity, and its construction method. The semi-flexible pavement uses a porous composite skeleton and a cement-based grout filling the skeleton. The porous composite skeleton includes silicon carbide aggregate and a heat-reflective binder, wherein the heat-reflective binder is a mixture containing acrylic emulsion, TiO2, and Al2O3. The cement-based grout includes a main grout system composed of magnesium ammonium phosphate cement, silicate cement, fine sand, and silicon carbide, as well as admixtures. During construction, the cement-based grout is injected into the porous composite skeleton. This invention's semi-flexible pavement integrates the three characteristics of "heat reflection, high thermal conductivity, and excellent road performance," achieving high solar radiation reflection, reducing pavement heat absorption, rapidly dissipating surface temperature, solving pavement rutting problems, and mitigating the urban "heat island effect." Simultaneously, it enhances the interface strength between the composite skeleton and the grout, compensating for insufficient crack resistance.

Description

Technical Field

[0001] This invention belongs to the field of semi-flexible pavement construction technology, and particularly relates to a semi-flexible pavement with heat reflection and high thermal conductivity and its construction method. Background Technology

[0003] Currently, technologies to enhance the high-temperature performance of asphalt mixtures or to cool asphalt pavements are commonly used to alleviate high-temperature rutting in asphalt pavements. Technologies for enhancing asphalt mixtures include: modified asphalt (SBS-modified asphalt, SBR-modified asphalt, etc.), adjusting aggregate gradation (changing from suspension to interlocking), or adding modifiers (anti-rutting agents, etc.). However, due to the high heat absorption of asphalt materials, technologies to enhance the high-temperature performance of asphalt mixtures are unlikely to fundamentally solve the problems of high-temperature rutting and the heat island effect. In addition, asphalt pavement cooling technologies include: heat-reflective pavements (increasing the reflectivity of solar radiation), phase-change temperature-regulating pavements (using the material's phase change process to absorb or release heat), heat-insulating pavements (reducing the thermal conductivity of asphalt pavements to prevent heat from being conducted downwards), and high thermal conductivity pavements (increasing the thermal conductivity of the pavement surface to accelerate heat transfer to the subgrade). However, while road surface cooling technology can effectively reduce the surface temperature of asphalt pavement and alleviate the heat island effect, due to the special nature of the admixtures, it can have adverse effects on the long-term durability or road performance of the pavement. In particular, the high-temperature rutting resistance will decrease to varying degrees, making it difficult for this technology to achieve a balance between cooling effect and road performance.

[0004] As a type of pavement composite material, semi-flexible pavement is formed by injecting a highly fluid cement-based grout into a porous asphalt mixture with a porosity of 20-25%, followed by curing. The hardened cement-based material and the asphalt mixture skeleton jointly bear traffic loads, giving it the advantages of asphalt pavement (smoothness, comfort, anti-skid, and waterproof performance) while also possessing the high modulus, strong load-bearing capacity, and excellent durability of cement pavement. Therefore, compared to ordinary pavements, the "rigid-flexible" semi-flexible pavement exhibits excellent high-temperature rutting resistance and water stability. However, due to the weak bond strength between the porous asphalt mixture and the cement-based grout, the stress and strain of the porous asphalt mixture and the cement-based grout are difficult to coordinate during load-bearing, making the semi-flexible pavement prone to cracking. This affects its service life and hinders the full realization of its superior rutting resistance.

[0005] Based on this, a new type of pavement is designed based on flexible pavement technology to improve the pavement's high-temperature rutting resistance while taking into account its cooling characteristics, thereby achieving a dual improvement in pavement cooling effect and road performance. Summary of the Invention

[0006] Purpose of the invention: The technical problem to be solved by the present invention is to provide a semi-flexible pavement that integrates the three characteristics of "heat reflection, high thermal conductivity and excellent road performance". It achieves the goals of high reflection of solar radiation, reducing heat absorption of the pavement, rapid dissipation of pavement surface temperature, solving pavement rutting disease and alleviating the urban "heat island effect", while also enhancing the strength of the interface between the mixture skeleton and the grouting material to make up for its insufficient crack resistance.

[0007] Technical solution: The present invention realizes a heat-reflective and high thermal conductivity semi-flexible pavement, the material of which includes a porous mixture skeleton and a cement-based grout filling the porous mixture skeleton;

[0008] The porous composite skeleton includes silicon carbide aggregate and heat-reflective binder, wherein the heat-reflective binder is a mixture containing acrylic emulsion, TiO2 and Al2O3;

[0009] The cement-based grouting material consists of a main grouting system composed of magnesium ammonium phosphate cement, silicate cement, fine sand and silicon carbide, as well as admixtures.

[0010] This invention addresses the problem that existing road surface cooling technologies cannot simultaneously achieve both high-temperature rutting resistance and high-temperature rutting resistance. By using semi-flexible pavement materials as the application carrier and combining "heat reflection technology" and "high thermal conductivity technology," it achieves a dual improvement in both high-temperature rutting resistance and cooling effect, while also solving the problem of cracking in semi-flexible pavements and extending their service life.

[0011] Specifically, this invention uses silicon carbide aggregates of different particle sizes with high thermal conductivity to prepare a high thermal conductivity porous composite skeleton. It uses acrylic resin emulsion combined with rutile nano-TiO2 and nano-Al2O3 as a semi-flexible pavement binder with heat-reflective properties. Simultaneously, it utilizes magnesium ammonium phosphate cement, ordinary silicate cement, fine sand, silicon carbide fines, and various additives to prepare a high thermal conductivity cement-based grouting material. The semi-flexible pavement material prepared by this method, characterized by "heat reflection, high thermal conductivity, and excellent road performance," achieves rapid heat flow from top to bottom through the dual thermal conductivity channels of the "high thermal conductivity skeleton" and the "high thermal conductivity grouting material." The mechanism is as follows: Figure 1As shown. Simultaneously, by combining rutile nano-TiO2 and nano-Al2O3 with acrylic resin emulsion, TiO2 and Al2O3 are added to the acrylic emulsion to form a heat-reflective binder. After the reflective binder wets the aggregate, the acrylic emulsion cures into a film, firmly anchoring the nano-TiO2 and Al2O3 to the aggregate surface. On the one hand, this achieves high reflectivity of solar radiation on the road surface, reducing the absorption rate of solar radiation on the road surface. On the other hand, TiO2, as a crystal nucleus, can promote the formation and growth of hydration products (such as CSH gel) in cement-based grouting materials. Simultaneously, Al2O3 can undergo a secondary reaction with the hydration products of the grouting material, consuming Ca(OH)2 in the hydration products and generating calcium aluminate hydrate (CAH), thus making the grouting material-skeleton interface denser and stronger. This is beneficial for the densification of the transition zone between the porous mixture skeleton and the cement-based grouting material interface, improving the bonding strength between interfaces, and ultimately enhancing the overall crack resistance of the grouting composite mixture.

[0012]

[0013] Furthermore, magnesium ammonium phosphate cement, with a higher thermal conductivity (up to 2.5 W / (m·K)), is used as the main base material for high thermal conductivity grouting. The hydration products of magnesium ammonium phosphate cement, including MgNH4PO4·6H2O, other hydration products such as MgHPO4·3H2O, and the amorphous Mg-P gel system, can achieve rapid strength growth within 3 hours. Its hydration process is accompanied by slight volume expansion, which, combined with its early rapid hardening characteristics, helps to achieve a balance between early strength, micro-expansion, and volume stability. The addition of low-cost silicate cement helps reduce the overall cost of high thermal conductivity cement-based grouting, and its later strength increases steadily with good toughness. Moreover, the acidic phosphates in the hydration products of magnesium ammonium phosphate cement can undergo surface chemical reactions with the hydration products of silicate cement, Ca(OH)2 and CSH, to form a Ca-P phase gel, which can further enhance the strength of the grout. Significantly improving the bonding strength between the porous mixture skeleton and the grout interface, as well as its internal interface, is beneficial for enhancing the crack resistance of semi-flexible pavements. Silicon carbide, as a high thermal conductivity filler (up to 490 W / (m·K)), can be used to improve the thermal conductivity of the grout, and silicon carbide powder is beneficial for improving the compressive strength, bonding strength between the porous mixture skeleton and the grout interface, and abrasion resistance of cement-based systems. Adding fine sand to the grout helps improve its density, fluidity, and compressive strength. The admixture system consists of an accelerator (calcium formate and lithium carbonate), a retarder (borax and sodium gluconate), and a water-reducing agent (polycarboxylate superplasticizer and naphthalene superplasticizer). These three admixtures can achieve early strength, retarding, and dispersion in the grout, thus meeting the performance requirements of ultra-early strength, good fluidity, and good anti-dispersion properties.

[0014]

[0015] .

[0016] Furthermore, the mass ratio of silicon carbide aggregate to heat-reflective binder in the porous composite skeleton used in this semi-flexible pavement is 100:(15-20).

[0017] Furthermore, the mass ratio of acrylic emulsion, TiO2 and Al2O3 in the heat-reflective binder used in this semi-flexible pavement is (7-8):(2-3):(3-4).

[0018] Furthermore, the mass ratio of magnesium ammonium phosphate cement, silicate cement, fine sand and silicon carbide in the main grouting system used in this semi-flexible pavement is (6-7):(2-3):(2-3):(2-2.5).

[0019] Furthermore, the admixtures used in this semi-flexible pavement include calcium formate (0.5%-1.2% by mass), lithium carbonate (0.1-0.2%), sodium gluconate (0.05-0.1%), borax (0.1-0.2%), polycarboxylate superplasticizer (0.3-0.5%), and naphthalene-based superplasticizer (0.5-1.5%), respectively.

[0020] Furthermore, the gradation of the silicon carbide aggregate used in this semi-flexible pavement is m (10~15mm):m (5~10mm):m (3~5mm):m (0~3mm) = (45-55):(35-40):(2-8):(3-12).

[0021] Furthermore, the fine sand in the cement-based grout used in this semi-flexible pavement has a fineness of 80-120 mesh, and the silicon carbide has a fineness of 80-220 mesh.

[0022] The construction method for the semi-flexible pavement of the present invention includes the following steps:

[0023] (1) Preparation of porous composite skeleton: TiO2 and Al2O3 are added to acrylic emulsion and stirred to obtain heat reflective binder; silicon carbide aggregate is heated to 50-60℃ and heat reflective binder is added under this temperature condition, stirred for 60-90s, and after curing, porous composite skeleton is obtained.

[0024] (2) Preparation of cement-based grouting material: Mix magnesium ammonium phosphate cement, silicate cement, fine sand, silicon carbide and admixtures for 2-3 minutes, add water according to the water-cement ratio, mix for 4-6 minutes to obtain grouting material;

[0025] (3) Inject cement-based grout into the interconnected gaps of the porous mixture skeleton until no air bubbles seep out from the top, and scrape off the excess grout from the top. After curing, it is ready.

[0026] Beneficial effects: Compared with the prior art, the significant advantages of this invention are as follows: By combining heat-reflective binders, high thermal conductivity aggregate skeletons, and high thermal conductivity grouting materials to prepare semi-flexible pavement materials, the goal of "heat reflection, high thermal conductivity, and excellent road performance" is achieved. This allows heat on the road surface to flow rapidly from top to bottom and reduces the absorption rate of solar radiation on the road surface, effectively reducing the road surface temperature and alleviating the urban heat island effect. At the same time, thanks to the interfacial physicochemical effect between the heat-reflective binders and the high thermal conductivity grouting materials, and the secondary reaction occurring inside the high thermal conductivity grouting materials, the density and bonding strength of the porous mixture-grouting material interface are improved, alleviating the shortcomings of insufficient crack resistance in semi-flexible pavement materials. This allows the semi-flexible pavement to achieve both significant cooling effects and excellent road performance (high-temperature rutting resistance, low-temperature crack resistance, fatigue resistance, and water damage resistance, etc.), greatly extending the service life of the semi-flexible pavement. Attached Figure Description

[0027] Figure 1 This is a schematic diagram illustrating the principle of road surface heat reflection and high thermal conductivity of the present invention;

[0028] Figure 2 This is a schematic diagram of the irradiation test of the present invention. Detailed Implementation

[0029] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0030] The raw materials used in the high thermal conductivity grouting material of this invention are: magnesium ammonium phosphate cement (powder, phosphorus-magnesium ratio 1 / 5); silicate cement (powder, grade 42.5); calcium formate (powder, industrial grade); lithium carbonate (powder, industrial grade); borax (powder, industrial grade); sodium gluconate (powder, industrial grade); polycarboxylate superplasticizer (powder, industrial grade, water reduction rate 35%); naphthalene superplasticizer (powder, industrial grade, water reduction rate 20%); fine sand (quartz sand, fineness 80-120 mesh); and silicon carbide (fineness 80 mesh).

[0031] The silicon carbide aggregate used in the porous composite skeleton of this invention has a gradation of m(10~15mm):m(5~10mm):m(3~5mm):m(0~3mm) = (45-55):(35-40):(2-8):(3-12). The acrylic emulsion is water-based and has a solid content of 50%. Nano TiO2 (rutile type, fineness: 50nm); nano Al2O3 (fineness: 50nm).

[0032] Black silicon carbide aggregates have high thermal conductivity (up to 130 W / (m·K)) and their mechanical properties (elastic modulus ≥450 GPa) are higher than those of common road aggregates (elastic modulus ≈55 GPa). Acrylic resins have relatively high refractive indices (1.41~1.47). Rutile nano-TiO2 has a high refractive index (up to 2.9); Al2O3 has a refractive index of 1.8.

[0033] Example 1

[0034] The semi-flexible pavement of this embodiment 1 comprises the following materials:

[0035] (1) Porous mixed material skeleton: black silicon carbide aggregate and heat reflective binder in a mass ratio of 100:18; wherein, the heat reflective binder includes acrylic emulsion, TiO2 and Al2O3 in a mass ratio of 7:2:3.

[0036] (2) Cement-based grouting material: The main system consists of magnesium ammonium phosphate cement, silicate cement, fine sand and silicon carbide in a mass ratio of 6:2:2:2, and calcium formate, lithium carbonate, sodium gluconate, borax, polycarboxylate superplasticizer and naphthalene superplasticizer, accounting for 1% of the mass of the main system, respectively.

[0037] The construction method for the semi-flexible pavement in Example 1 includes the following steps:

[0038] a. According to the proportion in (1) above, heat the black silicon carbide aggregate to 50°C and set the temperature of the mixing pot to 50°C. First, put the black silicon carbide aggregate in the mixing pot and stir for 60s. Use a high-speed shearing machine to stir the acrylic emulsion at a speed of 300r / min for 5min. After adding nano TiO2 and Al2O3, shear at a speed of 500r / min for 15min. After adding the sheared acrylic emulsion of nano TiO2 and Al2O3 into the mixing pot, stir for 60s. Prepare a porous mixture skeleton according to the requirements of the "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTGE20-2025).

[0039] b. According to the proportions in (2) above, place magnesium ammonium phosphate cement, ordinary silicate cement, fine sand, silicon carbide and various additives in a cement paste mixer and mix for 2 minutes (slow speed, rotation: 140±5 r / min; revolution: 62±5 r / min); keep the mixer in working condition, and then slowly add water to the already mixed dry material according to the ratio (water-to-solid ratio 0.30-0.40), and mix for 4 minutes (fast speed, rotation: 285±10 r / min; revolution: 125±5 r / min). After mixing, according to the requirements of the "Test Procedures for Cement and Cement Concrete in Highway Engineering" (JTG 3420—2020) and the "Specifications for Road Grouting Semi-Flexible Pavement Technology" (T / CECSG:D51-01-2019), immediately take samples for flowability testing to ensure that the grouting material has sufficient fluidity.

[0040] c. Seal the sides and bottom of the porous mixture skeleton with plastic film to prevent leakage during grouting. After thoroughly mixing the grout, slowly pour it from the middle to the sides of the top of the porous mixture, allowing it to fill the interconnected voids of the porous mixture by its own weight until no air bubbles seep out from the top. Use a scraper to remove the excess grout from the top and cure it under standard curing conditions (temperature 20±1℃) for 3 days. Use a steel brush to grind off the excess grout on the top to expose the heat-reflective binder on the surface of the aggregate.

[0041] Example 2

[0042] The semi-flexible pavement of this embodiment 2 comprises the following materials:

[0043] (1) Porous mixed material skeleton: black silicon carbide aggregate and heat reflective binder in a mass ratio of 100:15; wherein, the heat reflective binder includes acrylic emulsion, TiO2 and Al2O3 in a mass ratio of 8:3:4.

[0044] (2) Cement-based grouting material: The main system consists of magnesium ammonium phosphate cement, silicate cement, fine sand and silicon carbide in a mass ratio of 7:3:3:2.5, and calcium formate, lithium carbonate, sodium gluconate, borax, polycarboxylate superplasticizer and naphthalene superplasticizer, accounting for 0.5% of the mass of the main system, respectively.

[0045] The construction method for the semi-flexible pavement in Example 2 includes the following steps:

[0046] a. According to the proportion in (1) above, heat the black silicon carbide aggregate to 50°C and set the temperature of the mixing pot to 50°C. First, put the black silicon carbide aggregate in the mixing pot and stir for 60s. Use a high-speed shearing machine to stir the acrylic emulsion at a speed of 300r / min for 5min. After adding nano TiO2 and Al2O3, shear at a speed of 500r / min for 15min. After shearing the acrylic emulsion of nano TiO2 and Al2O3, put it into the mixing pot and stir for 60s. Prepare a porous mixture skeleton according to the requirements of the "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTGE20-2025).

[0047] b. According to the proportions in (2) above, place magnesium ammonium phosphate cement, ordinary silicate cement, fine sand, silicon carbide and various additives in a cement paste mixer and mix for 2 minutes (slow speed, rotation: 140±5 r / min; revolution: 62±5 r / min); keep the mixer in working condition, and then slowly add water to the already mixed dry material according to the ratio (water-to-solid ratio 0.30-0.40), and mix for 4 minutes (fast speed, rotation: 285±10 r / min; revolution: 125±5 r / min). After mixing, according to the requirements of the "Test Procedures for Cement and Cement Concrete in Highway Engineering" (JTG 3420—2020) and the "Specifications for Road Grouting Semi-Flexible Pavement Technology" (T / CECSG:D51-01-2019), immediately take samples for flowability testing to ensure that the grouting material has sufficient fluidity.

[0048] c. Seal the sides and bottom of the porous mixture skeleton with plastic film to prevent leakage during grouting. After thoroughly mixing the grout, slowly pour it from the middle to the sides of the top of the porous mixture, allowing it to fill the interconnected voids of the porous mixture by its own weight until no air bubbles seep out from the top. Use a scraper to remove the excess grout from the top and cure it under standard curing conditions (temperature 20±1℃) for 3 days. Use a steel brush to grind off the excess grout on the top to expose the heat-reflective binder on the surface of the aggregate.

[0049] Example 3

[0050] The semi-flexible pavement of this embodiment 3 comprises the following materials:

[0051] (1) Porous mixed material skeleton: black silicon carbide aggregate and heat reflective binder in a mass ratio of 100:20; wherein, the heat reflective binder includes acrylic emulsion, TiO2 and Al2O3 in a mass ratio of 8:3:4.

[0052] (2) Cement-based grouting material: The main system consists of magnesium ammonium phosphate cement, silicate cement, fine sand and silicon carbide in a mass ratio of 7:3:3:2.5, and calcium formate, lithium carbonate, sodium gluconate, borax, polycarboxylate superplasticizer and naphthalene superplasticizer, respectively, accounting for 1.2% of the main system mass.

[0053] The construction method for the semi-flexible pavement in Example 3 includes the following steps:

[0054] a. According to the proportion in (1) above, heat the black silicon carbide aggregate to 50°C and set the temperature of the mixing pot to 50°C. First, put the black silicon carbide aggregate in the mixing pot and stir for 60s. Use a high-speed shearing machine to stir the acrylic emulsion at a speed of 300r / min for 5min. After adding nano TiO2 and Al2O3, shear at a speed of 500r / min for 15min. After shearing the acrylic emulsion of nano TiO2 and Al2O3, put it into the mixing pot and stir for 60s. Prepare a porous mixture skeleton according to the requirements of the "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTGE20-2025).

[0055] b. According to the proportions in (2) above, place magnesium ammonium phosphate cement, ordinary silicate cement, fine sand, silicon carbide and various additives in a cement paste mixer and mix for 2 minutes (slow speed, rotation: 140±5 r / min; revolution: 62±5 r / min); keep the mixer in working condition, and then slowly add water to the already mixed dry material according to the ratio (water-to-solid ratio 0.30-0.40), and mix for 4 minutes (fast speed, rotation: 285±10 r / min; revolution: 125±5 r / min). After mixing, according to the requirements of the "Test Procedures for Cement and Cement Concrete in Highway Engineering" (JTG 3420—2020) and the "Specifications for Road Grouting Semi-Flexible Pavement Technology" (T / CECSG:D51-01-2019), immediately take samples for flowability testing to ensure that the grouting material has sufficient fluidity.

[0056] c. Seal the sides and bottom of the porous mixture skeleton with plastic film to prevent leakage during grouting. After thoroughly mixing the grout, slowly pour it from the middle to the sides of the top of the porous mixture, allowing it to fill the interconnected voids of the porous mixture by its own weight until no air bubbles seep out from the top. Use a scraper to remove the excess grout from the top and cure it under standard curing conditions (temperature 20±1℃) for 3 days. Use a steel brush to grind off the excess grout on the top to expose the heat-reflective binder on the surface of the aggregate.

[0057] Performance testing

[0058] According to the semi-flexible pavement of the present invention, comparative example 1 was prepared with a binder without reflective filler (i.e., acrylic emulsion only). Comparative example 2 was prepared with a binder composed of acrylic emulsion and nano-silica SiO2 reflective filler (the mass ratio of acrylic emulsion to nano-silica SiO2 was 7:5). Semi-flexible pavement material specimens of the heat-reflective binder of the present invention were also prepared. The specimen size was referenced to a standard rutted slab specimen of 300 mm × 300 mm × 50 mm. Indoor irradiation tests were conducted on the rutted slab specimens, such as... Figure 2 As shown, to reduce heat loss, the rutted slab specimen was wrapped with insulating foam around its sides and bottom, and the gaps between the specimen and the insulating material were filled with thermally conductive silicone grease. A 500 W tungsten iodine lamp was used as the irradiation source, with the irradiation source 60 cm away from the top of the specimen. A multi-channel temperature monitoring instrument was used to record temperature changes (monitored once every 2 hours). Temperature sensors were placed at 0 cm, 2.5 cm, and 5 cm away from the top of the specimen. To simulate actual sunlight exposure time, the irradiation process lasted for 6 hours.

[0059] A rutted slab specimen (300 mm × 300 mm × 50 mm) containing non-reflective filler, nano-silica SiO2 reflective filler, and the semi-flexible pavement material of this invention was prepared. Referring to the specification "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG 3410-2025), the rutted slab specimen was cut into small beams of 250 mm × 30 mm × 35 mm. A low-temperature bending test (-10℃) was conducted using a UTM-250 instrument. The loading position was located at the top center of the small beam specimen, with the support points located on both sides of the bottom of the small beam specimen. The span was 200 mm, and the top loading speed was set to 50 mm / min. The load-displacement curves were recorded, and the failure strain was calculated according to the specification.

[0060] Table 1. Comparison of cooling performance and crack resistance of different types of semi-flexible pavement materials

[0061]

[0062] In addition, based on the test method of Example 1, the road surface materials of Examples 2 and 3 were also used for performance testing, and the results are shown in Table 2 below.

[0063] Table 2. Cooling performance and crack resistance of the semi-flexible pavement materials in Examples 2 and 3

[0064]

[0065] As shown in Table 1, compared with other types of semi-flexible pavement materials, the semi-flexible pavement material of this invention exhibits superior cooling and crack resistance. Compared with the non-reflective filler group and the nano-silica filler group, its failure strain increase rate is 25.0% and 21.1%, respectively, and the temperature drop at 0 cm for 6 hours is 4.7℃ and 2.8℃, respectively. This demonstrates that the heat-reflective binder designed in this invention is beneficial to achieving the goal of "heat reflection, high thermal conductivity, and excellent road performance" of semi-flexible pavement. Furthermore, the data in Table 2 verify the stability of the experimental results, fully demonstrating that the material system of this invention can achieve the aforementioned claimed technical effects in semi-flexible pavement.

[0066] In addition to the above embodiments, the technical effects claimed by the present invention can be achieved by using the raw material components and process parameters defined by the present invention, and therefore no further experimental verification is required.

Claims

1. A semi-flexible pavement that achieves high thermal reflectance-high thermal conductivity, characterized by, The materials used in this semi-flexible pavement include a porous mixture skeleton and a cement-based grout filling the porous mixture skeleton; The porous composite skeleton includes silicon carbide aggregate and heat-reflective binder, wherein the heat-reflective binder is a mixture containing acrylic emulsion, TiO2 and Al2O3; The cement-based grouting material includes a main grouting material system composed of magnesium ammonium phosphate cement, silicate cement, fine sand and silicon carbide, as well as admixtures.

2. The semi-flexible pavement achieving heat reflection-high thermal conductivity according to claim 1, wherein, The mass ratio of silicon carbide aggregate to heat-reflective binder in the porous composite skeleton is 100:(15-20).

3. The semi-flexible pavement achieving heat reflection-high thermal conductivity according to claim 1, wherein, The mass ratio of acrylic emulsion, TiO2 and Al2O3 in the heat reflective binder is (7-8):(2-3):(3-4).

4. The semi-flexible pavement achieving heat reflection-high thermal conductivity according to claim 1, wherein, The mass ratio of magnesium ammonium phosphate cement, silicate cement, fine sand and silicon carbide in the main grouting system is (6-7):(2-3):(2-3):(2-2.5).

5. The semi-flexible pavement achieving heat reflection-high thermal conductivity according to claim 1, wherein, The admixtures include calcium formate (0.5%-1.2% by mass), lithium carbonate (0.1%-0.2%), sodium gluconate (0.05%-0.1%), borax (0.1%-0.2%), polycarboxylate superplasticizer (0.3%-0.5%), and naphthalene-based superplasticizer (0.5%-1.5%), each accounting for 0.5%-1.5% of the main grout system mass.

6. The semi-flexible pavement achieving heat reflection-high thermal conductivity according to claim 1, wherein, The gradation of the silicon carbide aggregate is m (10~15mm):m (5~10mm):m (3~5mm):m (0~3mm) = (45-55):(35-40):(2-8):(3-12).

7. The semi-flexible pavement achieving heat reflection-high thermal conductivity according to claim 1, wherein, The fine sand in the cement-based grout has a fineness of 80-120 mesh, and the silicon carbide has a fineness of 80-220 mesh.

8. The method of claim 1, wherein the semi-flexible pavement is constructed by the steps of: Includes the following steps: (1) Preparation of porous composite skeleton: TiO2 and Al2O3 are added to acrylic emulsion and stirred to obtain heat reflective binder; silicon carbide aggregate is heated to 50-60℃ and heat reflective binder is added under this temperature condition, stirred for 60-90s, and after curing, porous composite skeleton is obtained. (2) Preparation of cement-based grouting material: Mix magnesium ammonium phosphate cement, silicate cement, fine sand, silicon carbide and admixtures for 2-3 minutes, add water according to the water-cement ratio, mix for 4-6 minutes to obtain grouting material; (3) Inject cement-based grout into the interconnected gaps of the porous mixture skeleton until no air bubbles seep out from the top, scrape off the excess grout from the top, and then cure.

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