All-steel slag pavement structure, preparation method and application

Abstract

The application provides a full-steel slag pavement structure, a preparation method and application. The full-steel slag pavement structure comprises a bottom base layer, a lower base layer, an upper base layer, a lower surface layer, a middle surface layer and an upper surface layer, wherein all the aggregates are steel slag; the bottom base layer is a graded steel slag layer and comprises steel slag and water; the lower base layer and the upper base layer are cement stabilized steel slag layers and comprise cement, steel slag and water; the lower surface layer and the middle surface layer are ordinary asphalt mixture layers and comprise base asphalt and steel slag; and the upper surface layer is a high modulus asphalt mixture layer and comprises high modulus asphalt and steel slag. The application is based on unmodified steel slag and can be used for designing a full-steel slag pavement structure, so that steel slag can be used on a large scale to prepare pavement structure materials, and the service performance and service life of the steel slag pavement structure can be effectively improved.

Description

Technical Field

[0001] This invention relates to the field of highway engineering construction, and in particular to an all-steel slag pavement structure, its preparation method, and its application. Background Technology

[0002] On the one hand, highway construction consumes a large amount of sand and gravel aggregate, leading to a shortage of mineral resources, and conventional sand and gravel mining is insufficient to meet the needs of highway construction. On the other hand, the overall resource utilization rate of steel slag is not high. Rationally using steel slag in road engineering construction is one effective way to solve the above problems. However, because steel slag contains free calcium oxide and magnesium oxide, it has a certain degree of expansion, resulting in poor stability. Directly using it in road materials makes it difficult to obtain high-performance products. Existing technologies generally achieve the resource utilization of steel slag in asphalt mixtures by modifying it and combining it with other mineral materials.

[0003] Chinese invention patent application CN118324447A discloses a modified steel slag asphalt mixture and its preparation method. The mixture comprises 100 parts steel slag aggregate, 6-8 parts steel slag modifier, 4-6 parts asphalt, and 4-12 parts mineral powder. The steel slag content in the steel slag aggregate is 75-100 wt%. The steel slag aggregate forms the skeleton of the modified steel slag asphalt mixture. A layer of steel slag modifier is bonded and coated on the surface of the steel slag aggregate, and this modifier bonds with the asphalt to form a cross-linked spatial network structure. The mineral powder adheres to the asphalt. Although this patent application yields an asphalt mixture product based on steel slag, it still requires modification of the steel slag and the combined use of other mineral powders. It does not provide a structural design for an all-steel slag pavement based solely on unmodified steel slag.

[0004] Therefore, it is necessary to provide an all-steel slag pavement structure, its preparation method, and its application to solve the technical problem of how to design an all-steel slag pavement structure based on unmodified steel slag. Summary of the Invention

[0005] The main objective of this invention is to provide an all-steel slag pavement structure, its preparation method, and its application, aiming to solve the aforementioned technical problem of how to design an all-steel slag pavement structure based on unmodified steel slag.

[0006] To achieve the above objectives, the present invention provides an all-steel slag pavement structure, comprising: a subbase, a lower base, an upper base, a lower surface layer, an intermediate surface layer, and an upper surface layer, all composed of steel slag aggregates;

[0007] In the aforementioned subbase, the passing rates of steel slag through sieves with apertures of 37.5mm, 4.75mm, 0.6mm, and 0.075mm are 100%, 50-70%, 15-30%, and 7-15%, respectively.

[0008] In the lower and upper base layers, the sieve passing rates of steel slag with sieve openings of 31.5mm, 26.5mm, 19mm, 9.5mm, 4.75mm, 2.36mm, 0.6mm, and 0.075mm are 100%, 90-100%, 81-90%, 57-77%, 39-59%, 22-34%, 12-26%, and 5-10%, respectively.

[0009] In the lower layer, the sieve passing rates of steel slag with apertures of 31.5mm, 26.5mm, 19mm, 16mm, 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, and 0.075mm are 100%, 90-100%, 75-83%, 65-74%, 57-67%, 45-55%, 24-38%, 16-30%, 12-23%, 8-16%, 5-11%, 4-9%, and 2-5%, respectively.

[0010] In the intermediate layer, the sieve passing rates of steel slag with sieve openings of 26.5mm, 19mm, 16mm, 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, and 0.075mm are 100%, 90-100%, 78-85%, 62-71%, 50-61%, 26-41%, 16-31%, 12-23%, 8-16%, 5-11%, 4-9%, and 2-5%, respectively.

[0011] In the upper layer, the sieve passing rates of steel slag with sieve openings of 16mm, 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, and 0.075mm are 100%, 90-100%, 68-77%, 38-53%, 24-37%, 15-27%, 10-19%, 7-14%, 5-10%, and 2-6%, respectively.

[0012] Furthermore, the mixture of the subbase layer includes steel slag and water; the mixtures of the lower base layer and the upper base layer both include cement, steel slag, and water; the mixtures of the lower layer and the middle layer both include base asphalt and steel slag; and the mixture of the upper layer includes high-modulus asphalt and steel slag.

[0013] Furthermore, in the mixture of the subbase layer, the mass ratio of steel slag to water is 91~94:6~9; in the mixture of the lower base layer and the upper base layer, the mass ratio of cement, steel slag, and water is 1~2:91~92:6~8; in the mixture of the lower layer, the mass ratio of base asphalt to steel slag is 3~5:95~97; in the mixture of the intermediate layer, the mass ratio of base asphalt to steel slag is 3~5:95~97; and in the mixture of the upper layer, the mass ratio of high modulus asphalt to steel slag is 4~5:95~96.

[0014] Furthermore, the performance requirements of the high modulus asphalt in the upper layer mixture include: penetration (25℃, 100g, 0.1mm) of 25~35, softening point (℃) ≥70, ductility (10℃, 5cm / min) ≥20, kinematic viscosity (175℃ Pa·s) ≤1, penetration ratio of residue after RTFOT (25℃, %) ≥70, and ductility of residue after RTFOT (10℃, cm) ≥10.

[0015] Furthermore, the apparent density of the steel slag is ≥2.9 g / cm³. 3 Crushing value ≤20%.

[0016] Furthermore, the thickness of the base layer is 15-20cm, the thickness of the lower base layer is 15-20cm, the thickness of the upper base layer is 15-20cm, the thickness of the lower layer is 8-10cm, the thickness of the middle layer is 6-8cm, and the thickness of the upper layer is 4-6cm.

[0017] Furthermore, the subbase layer, the lower base layer, the upper base layer, the lower surface layer, the middle surface layer, and the upper surface layer are arranged sequentially from bottom to top.

[0018] The present invention also provides a method for preparing an all-steel slag pavement structure as described above, comprising: obtaining the subbase, lower base, upper base, lower surface layer, intermediate surface layer, and upper surface layer, all of which are composed of steel slag aggregates; and laying the subbase, lower base, upper base, lower surface layer, intermediate surface layer, and upper surface layer sequentially from bottom to top.

[0019] Furthermore, a steel slag micro powder bonding layer is provided between the subbase and the lower base; a steel slag micro powder bonding layer is provided between the lower base and the upper base; an emulsified asphalt tack coat is provided between the upper base and the lower layer; an SBS modified emulsified asphalt tack coat is provided between the lower layer and the intermediate layer; and an SBS modified emulsified asphalt tack coat is provided between the intermediate layer and the upper layer.

[0020] The present invention also provides an application of the all-steel slag pavement structure as described above in road construction.

[0021] Compared with the prior art, the present invention has at least the following advantages:

[0022] This invention designs an all-steel slag pavement structure based on unmodified steel slag, resulting in an all-steel slag pavement structure that can utilize steel slag on a large scale to prepare pavement structure materials and effectively improve the performance and service life of steel slag pavement structures. In the pavement structure designed by this invention, no pretreatment of the steel slag is required, and other related materials are conventional raw materials for engineering construction and are readily available; therefore, the all-steel slag pavement structure of this invention is easy to implement and readily applicable in engineering projects.

[0023] In the pavement structure of this invention, steel slag completely replaces traditional stone materials, including the base course and surface course. Since steel slag contains a certain amount of metallic elements, its coefficient of physical linear expansion is greater than that of limestone, granite, and other stones. If different stone design methods are used for the base course and surface course (e.g., steel slag for the base course and limestone for the surface course, or vice versa), the significant difference in deformation between the base course and surface course under large temperature variations can lead to instability in the pavement structure. The design method of this invention ensures the stability of the pavement structure under extreme temperature conditions. Furthermore, steel slag has a density more than 15% higher than traditional stone materials. If steel slag is used to partially replace traditional stone materials, the difference in aggregate density can easily lead to inaccuracies in the mass method for designing the mixture gradation. Therefore, the design method of this invention also ensures the accuracy of the pavement material gradation design.

[0024] In this invention, the base mixture is basically fine and densely graded. Since steel slag has a certain degree of expansion, it can offset the drying shrinkage of the steel slag mixture. In addition, the mixture contains a large amount of hydration-active micro powder, which can replace cement and continuously undergo hydration reaction, thus reducing the amount of cement in the steel slag mixture.

[0025] In this invention, the asphalt mixture in the surface layer is primarily coarse-grained and densely graded. Steel slag can be used in a balanced manner within the pavement structural materials, achieving full utilization of steel slag with different particle sizes. Due to the rough surface of the steel slag aggregate, the gradation design of the surface layer in this invention increases the interlocking effect between the steel slag aggregates. Furthermore, the surface of the steel slag aggregate contains alkaline-active components, which can chemically react with the acidic groups in the asphalt, generating energy exchange and forming adhesion. Therefore, increasing the amount of steel slag aggregate can enhance the adhesion between the asphalt and the aggregate. In addition, the gradation design of the surface layer in this invention can reduce the amount of asphalt used, and the use of high-modulus asphalt in the surface layer can improve the high-temperature stability of the steel slag asphalt mixture. Since fine steel slag aggregate is more prone to expansion and deformation than coarse steel slag aggregate, reducing the amount of fine steel slag aggregate in the asphalt mixture can also reduce the expansion and deformation of the steel slag asphalt mixture, ensuring its stability.

[0026] Furthermore, the all-steel slag pavement structure design of the present invention can greatly promote the application of steel slag in road engineering, reduce the mining of a large amount of natural stone, reduce the construction cost of road engineering, and reduce environmental damage and water and soil pollution caused by the mining of natural stone, thus having high economic, social and environmental benefits. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0028] Figure 1 This is a schematic diagram of the all-steel slag pavement structure in this invention.

[0029] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

[0032] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in the present invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, may be implemented using any prior art methods, devices, and materials similar to or equivalent to those described, used, or made of materials in the embodiments of this invention.

[0033] See Figure 1To understand this, the present invention provides an all-steel slag pavement structure, which includes: a subbase, a lower base, an upper base, a lower surface layer, an intermediate surface layer, and an upper surface layer, all made of steel slag aggregate; the subbase, the lower base, the upper base, the lower surface layer, the intermediate surface layer, and the upper surface layer are arranged sequentially from bottom to top.

[0034] In this invention, the subbase is a graded steel slag layer; the mixture of the subbase includes steel slag and water; the mass ratio of steel slag to water in the subbase is 91~94:6~9, further 91.8~93.3:6.7~8.2; the passing rates of the steel slag through 37.5mm, 4.75mm, 0.6mm, and 0.075mm sieves in the subbase are 100%, 50~70%, 15~30%, and 7~15%, respectively; the thickness of the subbase is 15~20cm.

[0035] Both the lower and upper base layers are cement-stabilized steel slag layers; the mixture of both the lower and upper base layers includes cement, steel slag, and water; the mass ratio of cement, steel slag, and water in the lower and upper base layers is 1~2:91~92:6~8, further being 1.2~1.8:91.2~91.8:6.4~7.6; the passing rates of the steel slag through 31.5mm, 26.5mm, 19mm, 9.5mm, 4.75mm, 2.36mm, 0.6mm, and 0.075mm sieves in the lower and upper base layers are 100%, 90~100%, 81~90%, 57~77%, 39~59%, 22~34%, 12~26%, and 5~10%, respectively; the thickness of the lower base layer is 15~20cm, and the thickness of the upper base layer is 15~20cm.

[0036] In this invention, the slag gradation particle size range of the subbase, lower base, and upper base is shown in Table 1:

[0037] Table 1. Particle size range of steel slag gradation in subbase, lower base, and upper base layers.

[0038]

[0039] As a further explanation of the particle size range of steel slag in the subbase, lower base, and upper base, in the subbase, the passing rates of steel slag through 37.5mm, 4.75mm, 0.6mm, and 0.075mm sieves are 100%, 52-70%, 18-30%, and 8-15%, respectively; or, 100%, 52-53%, 18-19%, and 8-9%, respectively; or, 100%, 69-70%, 29-30%, and 14-15%, respectively.

[0040] In the lower and upper base layers, the passing rates of the steel slag through sieves with apertures of 31.5mm, 26.5mm, 19mm, 9.5mm, 4.75mm, 2.36mm, 0.6mm, and 0.075mm are 100%, 91-100%, 83-90%, 59-77%, 41-59%, 24-34%, 15-26%, and 5-10%, respectively; or, 100%, 91-92%, 83-84%, 59-60%, 41-42%, 24-25%, 15-16%, and 5-6%, respectively; or, 100%, 99-100%, 89-90%, 76-77%, 58-59%, 33-34%, 25-26%, and 9-10%, respectively.

[0041] In this invention, the lower layer is a common asphalt mixture layer; the mixture of the lower layer includes base asphalt and steel slag; in the lower layer, the mass ratio of base asphalt to steel slag is 3~5:95~97, further 3.6~3.8:96.2~96.4; in the lower layer, the passing rates of the steel slag through sieves with apertures of 31.5mm, 26.5mm, 19mm, 16mm, 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, and 0.075mm are 100%, 90~100%, 75~83%, 65~74%, 57~67%, 45~55%, 24~38%, 16~30%, 12~23%, 8~16%, 5~11%, 4~9%, and 2~5%, respectively; the thickness of the lower layer is 8~10cm.

[0042] The intermediate layer is a common asphalt mixture layer; the mixture of the intermediate layer includes base asphalt and steel slag; in the intermediate layer, the mass ratio of base asphalt to steel slag is 3~5:95~97, further 3.8~4.0:96.0~96.2; in the intermediate layer, the passing rates of steel slag through sieves of 26.5mm, 19mm, 16mm, 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, and 0.075mm are 100%, 90~100%, 78~85%, 62~71%, 50~61%, 26~41%, 16~31%, 12~23%, 8~16%, 5~11%, 4~9%, and 2~5%, respectively; the thickness of the intermediate layer is 6~8cm.

[0043] The upper layer is a high-modulus asphalt mixture layer; the mixture of the upper layer includes high-modulus asphalt and steel slag; in the upper layer, the mass ratio of high-modulus asphalt to steel slag is 4~5:95~96, further 4.5~4.6:95.4~95.5; in the upper layer, the passing rates of steel slag through sieves with apertures of 16mm, 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, and 0.075mm are 100%, 90~100%, 68~77%, 38~53%, 24~37%, 15~27%, 10~19%, 7~14%, 5~10%, and 2~6%, respectively; the thickness of the upper layer is 4~6cm.

[0044] In this invention, the performance requirements of the high modulus asphalt include: penetration (25℃, 100g, 0.1mm) of 25~35, softening point (℃) ≥70, ductility (10℃, 5cm / min) ≥20, kinematic viscosity (175℃ Pa·s) ≤1, penetration ratio of residue after RTFOT (25℃, %) ≥70, and ductility of residue after RTFOT (10℃, cm) ≥10; as shown in Table 2.

[0045] Table 2 Performance Requirements for High Modulus Asphalt

[0046]

[0047] In this invention, the slag gradation particle size ranges of the upper layer, the middle layer, and the lower layer are shown in Table 3.

[0048] Table 3. Particle size range of steel slag gradation in the lower, middle, and upper layers.

[0049]

[0050] As a further explanation of the particle size range of steel slag in the lower layer, the middle layer, and the upper layer, in the lower layer, the sieve passing rates of steel slag with sieve openings of 31.5mm, 26.5mm, 19mm, 16mm, 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, and 0.075mm are 100%, 91~100%, 76~83%, 67~74%, 59~67%, 46~55%, 26~38%, 18~30%, 14~23%, and 9... respectively. ~16%, 6~11%, 5~9%, 2~5%; or, respectively 100%, 91~92%, 76~77%, 67~68%, 59~60%, 46~47%, 26~27%, 18~19%, 14~15%, 9~10%, 6~7%, 5~6%, 2~3%; or, respectively 100%, 99~100%, 82~83%, 73~74%, 66~67%, 54~55%, 37~38%, 29~30%, 22~23%, 15~16%, 10~11%, 8~9%, 4~5%.

[0051] In the intermediate layer, the sieve passing rates of steel slag with apertures of 26.5mm, 19mm, 16mm, 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, and 0.075mm are 100%, 91-100%, 78-85%, 63-71%, 51-61%, 28-41%, 17-31%, 13-23%, 9-16%, 6-11%, 4-9%, and 2-35%, respectively. 5%; or, respectively 100%, 91~92%, 78~79%, 63~64%, 51~52%, 28~29%, 17~18%, 13~14%, 9~10%, 6~7%, 4~5%, 2~3%; or, respectively 100%, 99~100%, 84~85%, 70~71%, 60~61%, 40~41%, 30~31%, 22~23%, 15~16%, 10~11%, 8~9%, 4~5%.

[0052] In the upper layer, the sieve passing rates of the steel slag with sieve openings of 16mm, 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, and 0.075mm are 100%, 91-100%, 69-77%, 39-53%, 26-37%, 16-27%, 11-19%, 8-14%, 5-10%, and 2-6%, respectively; or, 100%, 91-92%, 69-70%, 39-40%, 26-27%, 16-17%, 11-12%, 8-9%, 5-6%, and 2-3%, respectively; or, 100%, 99-100%, 76-77%, 52-53%, 36-37%, 26-27%, 18-19%, 13-14%, 9-10%, and 5-6%, respectively.

[0053] In this invention, the apparent density of the steel slag is ≥2.9 g / cm³. 3 The crushing value is ≤20%. In the gradation design of steel slag in this invention, the steel slag passing rate decreases or remains unchanged as the sieve aperture size decreases in each structural layer. In this invention, the cement is 32.5 grade or 42.5 general-purpose Portland cement; the cement used in this example is 42.5 general-purpose Portland cement.

[0054] The present invention also provides a method for preparing an all-steel slag pavement structure as described above, comprising: obtaining the subbase, lower base, upper base, lower surface layer, intermediate surface layer, and upper surface layer, all of which are composed of steel slag aggregates; and laying the subbase, lower base, upper base, lower surface layer, intermediate surface layer, and upper surface layer sequentially from bottom to top.

[0055] As an extension of the description of the all-steel slag pavement structure, in actual construction, a steel slag micro-powder bonding layer is set between the subbase and the lower base; a steel slag micro-powder bonding layer is set between the lower base and the upper base; an emulsified asphalt tack coat is set between the upper base and the lower layer; an SBS-modified emulsified asphalt tack coat is set between the lower layer and the intermediate layer; and an SBS-modified emulsified asphalt tack coat is set between the intermediate layer and the upper layer. Further, the steel slag used in the steel slag micro-powder bonding layer has a particle size of less than 0.075 mm, and its usage is 1~2 kg / m². 2 The emulsified asphalt usage for the prime coat is 0.7~1.3 L / m³. 2 In SBS-modified emulsified asphalt tack coats, the SBS modifier content is 3-5%, and the SBS-modified emulsified asphalt dosage is 0.3-0.6 L / m³. 2 .

[0056] This invention also provides an application of the all-steel slag pavement structure described above in road construction. It should be noted that existing technologies using steel slag in pavement materials for road construction generally involve modifying or subjecting the steel slag to specific processing. Furthermore, steel slag cannot completely replace natural aggregates, thus limiting its application in large quantities in asphalt pavement layers and hindering technology promotion. In contrast, the all-steel slag pavement structure of this invention uses only unmodified steel slag as aggregate, which can rapidly improve the resource utilization rate of steel slag and significantly reduce road construction costs, resulting in significant economic and social benefits.

[0057] The following are specific examples of the present invention:

[0058] Example 1

[0059] A full steel slag pavement structure includes, from bottom to top, a subbase, a lower base, an upper base, a lower surface layer, an intermediate surface layer, and an upper surface layer; the aggregates of the subbase, lower base, upper base, lower surface layer, intermediate surface layer, and upper surface layer are all made of steel slag.

[0060] The thickness of the subbase mixture is 16cm; the thickness of the upper and lower base mixtures is 18cm; the asphalt used in the intermediate and lower layers is ordinary asphalt (base asphalt), sourced from Foshan Gaofu 70# Grade A road petroleum asphalt, with a mixture thickness of 8cm for the lower layer and 6cm for the intermediate layer; the asphalt used in the upper layer is high-modulus asphalt, sourced from Jiangsu Baoli Asphalt Co., Ltd., with performance indicators shown in Table 4, and a mixture thickness of 4cm for the upper layer.

[0061] In this embodiment, the apparent density of the steel slag is 3.126 g / cm³. 3 The crushing value is 15%. In this embodiment, the steel slag aggregate gradation of each structural layer is shown in Table 5, and the mixture ratio of each structural layer is shown in Table 6; in this invention, the mixture ratio is a mass ratio.

[0062] Table 4 Performance test results of high modulus asphalt used in the upper layer

[0063]

[0064] Table 5 Aggregate gradation of each structural layer

[0065]

[0066] Table 6 Mix proportions of each structural layer

[0067]

[0068] Example 2

[0069] A full steel slag pavement structure includes, from bottom to top, a subbase, a lower base, an upper base, a lower surface layer, an intermediate surface layer, and an upper surface layer; the aggregates of the subbase, lower base, upper base, lower surface layer, intermediate surface layer, and upper surface layer are all made of steel slag.

[0070] The thickness of the mixture in the subbase is 16cm; the thickness of the mixture in both the upper and lower base layers is 18cm; the asphalt used in the intermediate and lower layers is ordinary asphalt (base asphalt), sourced from Foshan Gaofu 70# Grade A road petroleum asphalt, with a mixture thickness of 8cm in the lower layer and 6cm in the intermediate layer; the asphalt used in the upper layer is high-modulus asphalt, sourced from Jiangsu Baoli Asphalt Co., Ltd., with performance indicators the same as in Example 1, and a mixture thickness of 4cm in the upper layer.

[0071] In this embodiment, the apparent density of the steel slag is 3.126 g / cm³. 3 The crushing value is 15%. In this embodiment, the steel slag aggregate gradation of each structural layer is shown in Table 7, and the mixture composition of each structural layer is shown in Table 8.

[0072] Table 7 Aggregate gradation of each structural layer

[0073]

[0074] Table 8 Mix proportions of each structural layer

[0075]

[0076] Comparative Example 1

[0077] Compared to Example 1, this comparative example changes the aggregate gradation of the subbase, lower base, and upper base layers, while keeping other conditions unchanged. The specific aggregate gradation of the subbase, lower base, and upper base layers is shown in Table 9.

[0078] Table 9 Aggregate gradation of subbase, lower base, and upper base courses

[0079]

[0080] Comparative Example 2

[0081] Compared to Example 2, this comparative example changes the types of aggregates and the mix proportions in the subbase, lower base, and upper base layers, while keeping other conditions unchanged.

[0082] In this comparative example, the aggregates for the subbase, lower base, and upper base are steel slag and limestone crushed stone, with a mass ratio of 1:1. The gradation of the aggregates is the same as in Example 2. Specifically, the steel slag and limestone crushed stone are first screened separately, and then the steel slag and limestone crushed stone are controlled to meet the above gradation. Finally, the two are mixed.

[0083] Based on mass percentage, the mix proportion of the mixture in the subbase is steel slag: limestone crushed stone: water = 46.6: 46.6: 6.8; the mix proportion of the mixture in the lower and upper base courses is steel slag: limestone crushed stone: cement: water = 46.3: 46.3: 1.2: 6.2. The performance indicators of the limestone crushed stone meet the requirements of the "Technical Specifications for Construction of Highway Pavement Base Course" (JTG / T F20-2015).

[0084] Comparative Example 3

[0085] Compared to Example 2, this comparative example changes the aggregate gradation and mix proportion in the bottom layer, middle layer, and top layer, while keeping other conditions unchanged.

[0086] The specific aggregate gradations of the lower, middle, and upper layers are shown in Table 10, and the mixture proportions of the lower, middle, and upper layers are shown in Table 11.

[0087] Table 10 Aggregate gradation of lower, middle and upper layers

[0088]

[0089] Table 11 Mix proportions for the bottom layer, middle layer, and top layer

[0090]

[0091] Comparative Example 4

[0092] Compared to Example 1, this comparative example changes the types of aggregates and the mix proportions in the bottom layer, middle layer, and top layer, while keeping other conditions unchanged.

[0093] In this comparative example, the aggregates for the lower, middle, and upper layers are steel slag and limestone crushed stone, with a mass ratio of 1:1. The gradation of the aggregates is the same as in Example 1. Specifically, the steel slag and limestone crushed stone are first screened separately, and then the steel slag and limestone crushed stone are controlled to meet the above gradation. Finally, the two are mixed.

[0094] In this comparative example, the mix proportions of the lower, middle, and upper layers are shown in Table 12. The performance indicators of the limestone crushed stone meet the requirements of the "Technical Specification for Construction of Asphalt Pavement on Highways" (JTG / T F40-2004).

[0095] Table 12 Mix proportions for the bottom layer, middle layer, and top layer

[0096]

[0097] Analysis example 1

[0098] The mixtures of subbase, lower base, and upper base courses in Examples 1-2 and Comparative Examples 1-2 were subjected to 7-day unconfined compressive strength, 28-day compressive scouring resistance, and 90-day drying shrinkage strain tests. The specific test procedures were in accordance with the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" (JTG / T 3441-2024). The specific test results are shown in Table 13.

[0099] Table 13 Comparison of the performance of mixtures from subbase, lower base, and upper base courses

[0100]

[0101] Compared with Comparative Example 1, Examples 1-2 show improved strength, better erosion resistance, and reduced drying shrinkage, indicating that the all-steel slag mixture of the subbase, lower base, and upper base layers, using the gradation design of this invention, has better performance than other gradations.

[0102] Compared with Comparative Example 2, Examples 1-2 show improved strength, better erosion resistance, and reduced shrinkage, indicating that under the design gradation of this invention, the mixture of all-steel slag subbase, lower base, and upper base layers has better performance than the mixture containing some steel slag.

[0103] Analysis example 2

[0104] The mixtures of the top, middle, and bottom layers in Examples 1-2 and Comparative Examples 3-4 were tested for optimal asphalt-aggregate ratio, expansibility, rutting resistance, low-temperature crack resistance, and freeze-thaw splitting. The specific test procedures were in accordance with the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG / T E20-2011). The specific test results are shown in Table 14.

[0105] Table 14 Comparison of the performance of the mixture in the top, middle, and bottom layers

[0106]

[0107] Compared with Comparative Example 3, Examples 1-2 show an overall reduction in the optimal asphalt-aggregate ratio, a decrease in volume expansion rate, and improvements in dynamic stability, low-temperature flexural failure strain, and freeze-thaw splitting strength ratio. This indicates that the all-steel slag asphalt mixtures in the top, middle, and bottom layers, using the gradation design of this invention, reduce asphalt usage, lower costs, improve volume stability, and enhance high-temperature performance, low-temperature performance, and water stability.

[0108] Compared with Comparative Example 4, Examples 1-2 show an overall reduction in the optimal asphalt-aggregate ratio, a decrease in volume expansion rate, and improvements in dynamic stability, low-temperature flexural failure strain, and freeze-thaw splitting strength ratio. This indicates that under the design gradation of the present invention, compared with asphalt mixtures containing some steel slag in the top, middle, and bottom layers, the asphalt mixtures with all steel slag in the top, middle, and bottom layers have reduced asphalt usage, lower costs, better volume stability, and improved high-temperature performance, low-temperature performance, and water stability.

[0109] Analysis example 3

[0110] The thermal shrinkage coefficients of the mixtures in Examples 1-2 and Comparative Examples 1-4 were tested, with the specific test procedures referring to the "Test Procedures for Inorganic Binder Stabilized Materials in Highway Engineering" (JTG / T 3441-2024). The linear shrinkage coefficients of the mixtures in the top layer, middle layer, and bottom layer were tested, with the specific test procedures referring to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG / T E20-2011). The specific test results are shown in Table 15.

[0111] Table 15 Comparison of shrinkage coefficients of mixtures in each structural layer

[0112]

[0113] Compared with Comparative Examples 1-4, the thermal shrinkage coefficients of the upper base course, lower base course, and subbase course mixtures in Examples 1-2 are more similar to the linear shrinkage coefficients of the upper, middle, and lower asphalt course mixtures. This indicates that under temperature change conditions, the deformation of the upper base course, lower base course, and subbase course mixtures in Examples 1-2 is similar to that of the upper, middle, and lower asphalt course mixtures, thus effectively reducing pavement cracks caused by temperature changes.

[0114] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made under the technical concept of the present invention using the contents of the present invention specification and drawings, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A full steel slag pavement structure, characterized in that, include: The aggregate consists of steel slag in the subbase, lower base, upper base, lower surface, middle surface, and upper surface layers. In the aforementioned subbase, the passing rates of steel slag through sieves with apertures of 37.5mm, 4.75mm, 0.6mm, and 0.075mm are 100%, 52-70%, 18-30%, and 8-15%, respectively. In the lower and upper base layers, the sieve passing rates of steel slag with sieve openings of 31.5mm, 26.5mm, 19mm, 9.5mm, 4.75mm, 2.36mm, 0.6mm, and 0.075mm are 100%, 91-100%, 83-90%, 59-77%, 41-59%, 24-34%, 15-26%, and 5-10%, respectively. In the lower layer, the sieve passing rates of steel slag with apertures of 31.5mm, 26.5mm, 19mm, 16mm, 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, and 0.075mm are 100%, 91-100%, 76-83%, 67-74%, 59-67%, 46-55%, 26-38%, 18-30%, 14-23%, 9-16%, 6-11%, 5-9%, and 2-5%, respectively. In the intermediate layer, the sieve passing rates of steel slag with sieve openings of 26.5mm, 19mm, 16mm, 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, and 0.075mm are 100%, 91-100%, 78-85%, 63-71%, 51-61%, 28-41%, 17-31%, 13-23%, 9-16%, 6-11%, 4-9%, and 2-5%, respectively. In the upper layer, the sieve passing rates of steel slag with sieve openings of 16mm, 13.2mm, 9.5mm, 4.75mm, 2.36mm, 1.18mm, 0.6mm, 0.3mm, 0.15mm, and 0.075mm are 100%, 91-100%, 69-77%, 39-53%, 26-37%, 16-27%, 11-19%, 8-14%, 5-10%, and 2-6%, respectively. The subbase layer consists of steel slag and water in a mass ratio of 91-94:6-9; the lower and upper base layers consist of cement, steel slag, and water in a mass ratio of 1-2:91-92:6-8; the lower and middle layers consist of base asphalt and steel slag in a mass ratio of 3-5:95-97; and the upper layer consists of high-modulus asphalt and steel slag in a mass ratio of 4-5:95-96.

2. The all-steel slag pavement structure according to claim 1, characterized in that, The performance requirements for high modulus asphalt in the upper layer mixture include: penetration (25℃, 100g, 0.1mm) of 25~35, softening point (℃) ≥70, ductility (10℃, 5cm / min) ≥20, kinematic viscosity (175℃ Pa·s) ≤1, penetration ratio of residue after RTFOT (25℃, %) ≥70, and ductility of residue after RTFOT (10℃, cm) ≥10.

3. The all-steel slag pavement structure according to claim 1, characterized in that, The apparent density of steel slag is ≥2.9 g / cm³. 3 Crushing value ≤20%.

4. The all-steel slag pavement structure according to claim 1, characterized in that, The thickness of the base layer is 15-20cm, the thickness of the lower base layer is 15-20cm, the thickness of the upper base layer is 15-20cm, the thickness of the lower layer is 8-10cm, the thickness of the middle layer is 6-8cm, and the thickness of the upper layer is 4-6cm.

5. The all-steel slag pavement structure according to claim 1, characterized in that, The subbase, lower base, upper base, lower layer, middle layer, and upper layer are arranged sequentially from bottom to top.

6. A method for preparing an all-steel slag pavement structure as described in any one of claims 1-5, characterized in that, include: Obtain the subbase, lower base, upper base, lower bottom layer, middle layer, and upper top layer, all of which are composed of steel slag aggregate; and lay the subbase, lower base, upper base, lower bottom layer, middle layer, and upper top layer sequentially from bottom to top.

7. The method for preparing an all-steel slag pavement structure according to claim 6, characterized in that, A steel slag micro-powder bonding layer is provided between the subbase and the lower base; a steel slag micro-powder bonding layer is provided between the lower base and the upper base; an emulsified asphalt tack coat is provided between the upper base and the lower layer; an SBS modified emulsified asphalt tack coat is provided between the lower layer and the intermediate layer; and an SBS modified emulsified asphalt tack coat is provided between the intermediate layer and the upper layer.

8. The application of an all-steel slag pavement structure as described in any one of claims 1-5 in road construction.

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