Super sulfate cement stabilized steel slag macadam base material as well as preparation method and application thereof

Abstract

The invention discloses a super sulfate cement stabilized steel slag macadam base material and a preparation method and application thereof.The base material is composed of aggregate, super sulfate cement and water, the aggregate is composed of limestone aggregate and steel slag aggregate, and the super sulfate cement is desulfurized gypsum-based super sulfate cement; the super sulfate cement stabilized steel slag macadam base material disclosed by the invention is good in mechanical property, high in bearing capacity and deformation resistance and excellent in crack resistance; the preparation method is simple in construction process and easy to operate, the engineering construction efficiency is improved, the construction cost is reduced compared with that of similar high-performance materials, good economic benefits are achieved, economical efficiency and practicability are high, and carbon emission is remarkably reduced compared with that of traditional Portland cement; meanwhile, industrial solid waste pollution is reduced through utilization of the steel slag aggregate, dependence of road base material production on natural resources is greatly reduced, the low-carbon and environment-friendly development trend is met, and large-scale application and popularization in the field of road engineering are facilitated.

Description

Technical Field

[0001] The present invention relates to a base material, and in particular to a supersulphated cement stabilized steel slag and gravel base material, and also relates to a preparation method of the above base material and its application in the field of road engineering materials. Background Art

[0002] Cement stabilized gravel is a commonly used semi-rigid base material in current road engineering. It is mainly composed of cement, gravel and water mixed in a certain proportion, and relies on the hydration of cement to make the mixture coagulate and harden, so as to have high strength and good bearing capacity, and can effectively resist the stress generated by road traffic loads.

[0003] However, the existing cement stabilized gravel semi-rigid base materials face the following problems: (1) Carbon emission problem: A large amount of carbon dioxide will be emitted during the production process of cement due to the high-temperature calcination of raw materials such as limestone, which causes serious pollution to the environment and does not meet the requirements of low-carbon environmental protection for road engineering materials; (2) Easy cracking characteristics: During service, dry shrinkage and thermal shrinkage cracks are likely to occur in the cement stabilized gravel base. This is because the loss of internal moisture in cement stabilized gravel will cause dry shrinkage, and temperature changes will cause the volume of the material to change, thus generating thermal shrinkage. These cracks will reduce the durability of the road base, shorten the service life of the road, and increase the frequency and cost of road maintenance; Therefore, there is an urgent need to develop a road base material with good economy and practicability, which can be produced and constructed by existing equipment, reduce construction costs and improve engineering efficiency. Summary of the Invention

[0004] Object of the Invention: The object of the present invention is to provide a supersulphated cement stabilized steel slag and gravel base material with high bearing capacity, crack resistance and durability, and also provide a preparation method of the above base material with the advantage of low carbon emission and its application in the field of road engineering materials.

[0005] Technical Solution: The present invention discloses a supersulphated cement stabilized steel slag and gravel base material, and the base material is composed of the following materials in parts by weight: 100 parts of aggregate, 3.5 - 6.0 parts of supersulphated cement, and 4.0 - 5.5 parts of water; wherein, the aggregate is composed of the following materials in weight percentage: 45 - 60% of limestone aggregate and 40 - 55% of steel slag aggregate; the supersulphated cement is a desulfurized gypsum-based supersulphated cement, and is composed of the following materials in parts by weight: 70 - 80 parts of granulated blast furnace slag powder, 10 - 20 parts of dihydrate desulfurized gypsum, and 3 - 8 parts of Portland cement clinker.

[0006] Wherein, the granulated blast furnace slag powder is granulated blast furnace slag powder with a specific surface area ≥ 400m 2 / kg; the content of SO3 in the dihydrate desulfurized gypsum ≥ 35%; the content of C3S in the Portland cement clinker ≥ 50%.

[0007] Among them, the limestone aggregate has a particle size of 20 - 30 mm, 3 - 5 mm or less than 3 mm, and the steel slag aggregate has a particle size of 5 - 10 mm or 10 - 20 mm.

[0008] Among them, the aggregate is composed of the following materials by weight percentage: 21 - 28% of limestone aggregate with a particle size of 20 - 30 mm, 24 - 36% of steel slag aggregate with a particle size of 10 - 20 mm, 15 - 22% of steel slag aggregate with a particle size of 5 - 10 mm, 3 - 7% of limestone aggregate with a particle size of 3 - 5 mm, and 18 - 27% of limestone aggregate with a particle size less than 3 mm.

[0009] Among them, the steel slag aggregate is secondary - aged steel slag. The manufacturing method is as follows: After loading the steel slag into a closed mold, saturated steam and CO₂ are introduced to obtain primary - aged steel slag, where the pressure in the closed container is not less than 0.5 MPa; then the primary - aged steel slag is naturally stacked at normal temperature and pressure for more than 6 months to obtain secondary - aged steel slag.

[0010] Among them, the steel slag is converter steel slag, and its chemical composition is 40 - 50% CaO, 10 - 15% SiO₂, 15 - 25% FeO, and the free calcium oxide content ≤ 3%.

[0011] The preparation method of the above - mentioned supersulphate - cement - stabilized steel - slag gravel base material includes the following steps:

[0012] (1) Raw material preparation: Prepare steel slag aggregate, screen and classify the steel slag aggregate and limestone aggregate according to the particle - size requirements, and prepare the aggregate, supersulphate cement and water in proportion;

[0013] (2) Mixing and stirring: First, mix the steel slag aggregate and limestone aggregate evenly, add water and stir, then add supersulphate cement and continue to stir until evenly mixed to obtain the product.

[0014] Among them, in step (1), the manufacturing method of supersulphate cement is to mix granulated blast - furnace slag powder, gypsum dihydrate and Portland cement clinker in proportion and then grind to a specific surface area ≥ 380 m 2 / kg to obtain it.

[0015] The above - mentioned supersulphate - cement - stabilized steel - slag gravel base material can also be applied in the field of road engineering.

[0016] Among them, the application is as follows: Spread and roll the mixture into shape, use a combination of double - steel - wheel rollers and rubber - tired rollers for rolling. After forming, carry out wet curing for 7 - 10 days under the conditions of 20 - 25 °C and humidity ≥ 93%; further preferably, carry out wet curing for 7 - 10 days under the conditions of 20 - 25 °C and humidity ≥ 95%.

[0017] Principle of the invention: Traditional cement-stabilized macadam often uses aggregates with a single particle size or an unreasonable gradation, resulting in a loose skeleton, a large void ratio, and easy stress concentration. The supersulfate cement-stabilized steel slag macadam base course material of the present invention forms a "skeleton-dense" composite structure through the combination of steel slag aggregates and limestone aggregates and a reasonable multi-stage gradation design. After the converter steel slag is subjected to secondary aging treatment, the free calcium oxide content is ≤3%, and it has high hardness and surface roughness. As coarse and medium aggregates, it forms a skeleton support, significantly improving the compressive strength. Limestone has good toughness and low water absorption. As fine aggregates, it fills the gaps between the steel slag skeletons, reducing the void ratio to 8% - 12%, and at the same time reducing the shrinkage stress. At the same time, the hydration shrinkage rate of traditional portland cement is as high as 0.03% - 0.05%, which is prone to drying shrinkage cracks. The base course material of the present invention has excellent crack resistance. Supersulfate cement has a micro-expansion characteristic. The slag powder and gypsum dihydrate react to form ettringite under alkaline conditions, with an early expansion rate of 0.05% - 0.08%, effectively offsetting the drying shrinkage stress. The portland cement clinker accelerates the secondary hydration of the slag powder, generating C-S-H gel to fill the pores, further improving the compactness of the base course material. During the early hydration process, the active components on the surface of the steel slag aggregates undergo ion exchange with the supersulfate cement paste, forming a dense interfacial transition zone, and the interfacial bonding strength is increased by 20% - 30%, inhibiting the crack propagation path. At the same time, the microporous structure of the steel slag adsorbs the free water in the cement paste, reducing the internal humidity gradient and further reducing the thermal shrinkage strain. Through experimental verification, the drying shrinkage strain and thermal shrinkage strain of the materials of the present invention are significantly lower than those of the comparative materials using only limestone aggregates or only portland cement, significantly improving the durability of the road base course.

[0018] Beneficial effects: Compared with the prior art, the present invention has the following remarkable advantages:

[0019] (1) The supersulfate cement-stabilized steel slag macadam base course material of the present invention has good mechanical properties, strong load-bearing and anti-deformation capabilities, and excellent crack resistance. The 7-day compressive strength of Example 1 reaches 5.4 MPa, which is 28.6% higher than that of Comparative Example 1 and 42.1% higher than that of Comparative Example 2; the 28-day compressive strength reaches 7.9 MPa, which is 29.5% higher than that of Comparative Example 1 and 43.6% higher than that of Comparative Example 2. The dry shrinkage coefficient is reduced to 0.015%, which is 34.8% lower than that of Comparative Example 1, and the thermal shrinkage coefficient is 0.012% / °C, which is 33.3% lower than that of Comparative Example 1. Through the micro-expansion characteristic of supersulfate cement and the interfacial strengthening effect of steel slag aggregates, the crack resistance is improved by more than 1.5 times; the "skeleton-dense" structure formed by the aggregate gradation improves the anti-deformation ability of the material by 1.8 times, and the fatigue life in the cyclic load test is extended to 2.3 times that of the traditional material;

[0020] (2) In the supersulphate cement stabilized steel slag gravel base material of the present invention, the supersulphate cement uses industrial by-product slag and desulphurization gypsum as the main raw materials, and its carbon emissions during the production process are significantly reduced compared with traditional portland cement. At the same time, the utilization of steel slag aggregate reduces industrial solid waste pollution and greatly reduces the dependence of road base material production on natural resources, meeting the development trend of low-carbon environmental protection. (3) The preparation method of the base material of the present invention has simple construction technology, is easy to operate, improves the engineering construction efficiency, the construction cost is reduced compared with similar high-performance materials, has good economic benefits, strong economy and practicability, and is conducive to large-scale popularization and application in the field of road engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 is the limestone-steel slag composite gradation curve adopted by the present invention;

[0022] Figure 2 The SEM image of shows the C-S-H and ettringite composite structure formed at the interface between the steel slag surface and the cement paste. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The technical solution of the present invention will be further described below in conjunction with the embodiments. The test materials used in the embodiments can be obtained through conventional channels.

[0024] Embodiment 1

[0025] For the supersulphate cement stabilized steel slag gravel base material of the present invention, 25 kg of 1# limestone aggregate with a particle size of 20-30 mm, 30 kg of 2# steel slag aggregate with a particle size of 10-20 mm, 18 kg of 3# steel slag aggregate with a particle size of 5-10 mm, 5 kg of 4# limestone aggregate with a particle size of 3-5 mm, and 22 kg of 5# limestone aggregate with a particle size of 0-3 mm are selected. 4.5 kg of supersulphate cement (80 parts of slag powder, 15 parts of dihydrate desulphurization gypsum, and 5 parts of portland cement clinker) and 4.7 kg of water are prepared.

[0026] The preparation method of the supersulphate cement stabilized steel slag gravel base material of the present invention includes the following steps:

[0027] (1) Raw material preparation: Prepare steel slag aggregate, screen and classify the steel slag aggregate and limestone aggregate according to the particle size requirements, and prepare the aggregate, supersulphate cement and water in proportion;

[0028] (2) Mixing and stirring: Place the steel slag and limestone gravel in a mixer, first dry mix for 3-5 minutes to make the aggregate evenly mixed. Then add water and stir for 2-3 minutes to make the water evenly distributed in the aggregate. Finally, add supersulphate cement and continue to stir for 3-5 minutes until the color of the mixture is uniform.

[0029] The application of the supersulphate cement stabilized steel slag gravel base course material of the present invention is as follows: forming and curing. Pour the well-stirred mixture into a mold and vibrate it into shape with a vibrating compactor. Control the vibration time within 5 - 10 minutes to ensure the compactness of the specimen. After forming, place the specimen in a standard curing room (20 - 25°C, humidity 95%) for 7 days, and keep the surface of the specimen moist during the curing period.

[0030] Example 2

[0031] For the supersulphate cement stabilized steel slag gravel base course material of the present invention, select 25 kg of 1# limestone aggregate with a particle size of 20 - 30 mm, 30 kg of 2# steel slag aggregate with a particle size of 10 - 20 mm, 18 kg of 3# steel slag aggregate with a particle size of 5 - 10 mm, 5 kg of 4# limestone aggregate with a particle size of 3 - 5 mm, and 22 kg of 5# limestone aggregate with a particle size of 0 - 3 mm. 4.5 kg of supersulphate cement (75 parts of slag powder, 20 parts of dihydrate desulphurization gypsum, 5 parts of Portland cement clinker), and 4.7 kg of water.

[0032] The preparation method and application of the above supersulphate cement stabilized steel slag gravel base course material are the same as those in Example 1.

[0033] Example 3

[0034] For the supersulphate cement stabilized steel slag gravel base course material of the present invention, select 23 kg of 1# limestone aggregate with a particle size of 20 - 30 mm, 33 kg of 2# steel slag aggregate with a particle size of 10 - 20 mm, 16 kg of 3# steel slag aggregate with a particle size of 5 - 10 mm, 6 kg of 4# limestone aggregate with a particle size of 3 - 5 mm, and 22 kg of 5# limestone aggregate with a particle size of 0 - 3 mm. Prepare 4.5 kg of supersulphate cement (75 parts of slag powder, 20 parts of dihydrate desulphurization gypsum, 5 parts of Portland cement clinker) and 4.7 kg of water.

[0035] The preparation method and application of the above supersulphate cement stabilized steel slag gravel base course material are the same as those in Example 1.

[0036] Comparative Example 1

[0037] A mixed base course material. Compared with Example 1, only limestone aggregate is used: select 25 kg of 1# limestone aggregate with a particle size of 20 - 30 mm, 30 kg of 2# limestone aggregate with a particle size of 10 - 20 mm, 18 kg of 3# limestone aggregate with a particle size of 5 - 10 mm, 5 kg of 4# limestone aggregate with a particle size of 3 - 5 mm, and 22 kg of 5# limestone aggregate with a particle size of 0 - 3 mm. Prepare 4.5 kg of supersulphate cement (80 parts of slag powder, 15 parts of dihydrate desulphurization gypsum, 5 parts of Portland cement clinker) and 4.7 kg of water.

[0038] The preparation method and application of the above mixed base course material are the same as those in Example 1.

[0039] Comparative Example 2

[0040] A mixed base material. Compared with Example 1, only Portland cement is used: Select 25 kg of 1# limestone aggregate with a particle size of 20 - 30 mm, 30 kg of 2# steel slag aggregate with a particle size of 10 - 20 mm, 18 kg of 3# steel slag aggregate with a particle size of 5 - 10 mm, 5 kg of 4# limestone aggregate with a particle size of 3 - 5 mm, and 22 kg of 5# limestone aggregate with a particle size of 0 - 3 mm. Prepare 4.5 kg of Portland cement and 4.7 kg of water.

[0041] (1) Raw material preparation: Prepare steel slag aggregate, screen and classify the steel slag aggregate and limestone aggregate according to the particle size requirements, and prepare the aggregate, supersulfate cement and water in proportion;

[0042] (2) Mixing and stirring: Place the steel slag and limestone crushed stones in a mixer, dry mix for 3 - 5 minutes first to make the aggregate evenly mixed. Then add water and stir for 2 - 3 minutes to make the water evenly distributed in the aggregate. Finally, add Portland cement and continue to stir for 3 - 5 minutes until the color of the mixture is uniform.

[0043] The application of the above mixed base material is the same as that in Example 1.

[0044] Examples 1, 2, and 3 adopt the composite gradation as shown in the appendix Figure 1 to achieve a skeleton-dense structure through multi-gradation design. The coarse aggregate forms a mechanical skeleton, and the fine aggregate fills the voids to reduce shrinkage stress;

[0045] By mixing steel slag (5 - 20 mm) and limestone (0 - 30 mm) with different particle sizes in proportion, the coarse-grained steel slag forms a skeleton support, and the medium and fine-grained limestone fills the voids, reducing the void ratio of the mixture to 8% - 12%. This "skeleton-dense" structure significantly improves the compressive strength and anti-deformation ability of the material, while reducing shrinkage stress, thereby enhancing durability.

[0046] Perform performance tests on the base materials of the above examples and comparative examples:

[0047] Anti-cracking performance test:

[0048] Apply T0854 - 2024 "Test Method for Dry Shrinkage of Inorganic Binder Stabilized Materials" and use a shrinkage meter to measure the dry shrinkage coefficient of the material in a dry shrinkage chamber; Apply T0855 - 2024 "Test Method for Thermal Shrinkage of Inorganic Binder Stabilized Materials" and use the sensor method to measure the thermal shrinkage coefficient of the material.

[0049] Table 1. Anti-cracking performance test results of examples and comparative examples

[0050] Drying shrinkage coefficient (%) Thermal shrinkage coefficient (% / °C) Example 1 0.015 0.012 Example 2 0.018 0.012 Example 3 0.016 0.014 Comparative Example 1 0.023 0.018 Comparative Example 2 0.028 0.020

[0051] The results show that the dry shrinkage strain and thermal shrinkage strain of Example 1, Example 2 and Example 3 are significantly lower than those of the comparative examples. The dry shrinkage coefficients of Example 1, Example 2 and Example 3 are 34 - 51% lower than those of Comparative Example 1 and Comparative Example 2. It shows that the micro-expansion property of the material of the present invention effectively offsets the shrinkage effect and significantly improves the crack resistance. Due to the micro-expansion property of supersulphate cement, expansion stress is generated during the early hydration process, which offsets the shrinkage stress generated by the drying and temperature reduction of the material, thus avoiding the generation of cracks. At the same time, the properties of the steel slag aggregate itself also contribute to improving the toughness of the material, further enhancing the crack resistance ability.

[0052] Mechanical property test:

[0053] The specimens prepared in Example 1, Example 2, Example 3 and Comparative Example 1, Comparative Example 2 were respectively tested for unconfined compressive strength at 7 days and 28 days according to T0805 - 2024 "Test Method for Unconfined Compressive Strength of Inorganic Binder Stabilized Materials".

[0054] Table 2. Test results of mechanical properties of examples and comparative examples

[0055] 7-day compressive strength (MPa) 28-day compressive strength (MPa) Fatigue life (10,000 times) Example 1 5.4 7.9 23.5 Example 2 5.1 7.1 — Example 3 4.8 6.3 — Comparative Example 1 4.2 6.1 10.2 Comparative Example 2 3.8 5.5 8.7

[0056] The test results show that the 7-day compressive strengths of Example 1, Example 2 and Example 3 reach 5.4 MPa, 5.1 MPa and 4.8 MPa respectively, and the 28-day compressive strengths reach 7.9 MPa, 7.1 MPa and 6.3 MPa, and are all higher than those of the comparative examples. This shows that the supersulphate cement stabilized steel slag crushed stone base material of the present invention has high mechanical properties, and the strength continues to increase over time. Due to the reaction between the hydration products of supersulphate cement and the active components in the steel slag, more cementitious substances are generated, filling the voids between the aggregates and making the structure more dense, thus improving the compressive and flexural strengths. The reasonable aggregate gradation also provides strong support for the improvement of strength, and the aggregates with different particle sizes interlock with each other to form a stable skeleton structure.

[0057] Example 1 exhibits a fatigue life of 235,000 cycles, showing significant advantages compared to 102,000 cycles of Comparative Example 1 and 87,000 cycles of Comparative Example 2. This gap is attributed to the following points: Firstly, supersulphate cement has the property of micro-expansion. The ettringite generated in the early stage can effectively offset the shrinkage stress, thereby reducing the initiation of internal microcracks. Secondly, steel slag aggregate has an interface strengthening effect. The active components on the surface of steel slag react with the cement paste to form a dense interfacial transition zone, increasing the bond strength by 20%-30%, thus inhibiting the crack propagation. Thirdly, thanks to the skeleton-dense structure formed by the reasonable multi-level aggregate gradation, it constructs a stable skeleton support, reduces the stress concentration phenomenon, and delays the accumulation of fatigue damage. Fourthly, there is a microporous adsorption effect in steel slag, which can adsorb free water, reduce the humidity gradient, and decrease the thermal shrinkage strain, further enhancing the anti-fatigue performance of the material.

[0058] SEM scanning was carried out on Example 1, and the results are as shown in the appendix Figure 2 It shows that the surface of the steel slag aggregate is in a tightly combined state with the supersulphate cement paste. At the interface between the two, dense C-S-H gels and needle-like ettringite crystals are distributed. The formation of this composite structure can be attributed to the following aspects: Firstly, steel slag has chemical activity. Components such as CaO and FeO contained in converter steel slag will react with slag powder and desulphurized gypsum in an alkaline environment to generate ettringite (AFt) and C-S-H gels. Secondly, there is a synergistic effect among the hydration products. Among them, ettringite can produce a micro-expansion effect to compensate for shrinkage, while C-S-H gels play a role in filling pores, enhancing the density of the overall structure. Finally, the interfacial transition zone is strengthened. Through active ion exchange, chemical bonding is formed between the surface of steel slag and the paste, significantly increasing the interfacial bond strength and effectively inhibiting the crack propagation path. This structure is generated by the reaction of the active components of steel slag with the hydration products of supersulphate cement, significantly enhancing the interfacial bond strength and crack resistance.

[0059] Therefore, the present invention has developed a road base material with good economy and practicability, which can be produced and constructed using existing equipment, reducing the construction cost, improving the engineering efficiency, reducing the carbon emissions during the production of road base materials, reducing the negative impact on the environment, and achieving the goal of low-carbon environmental protection. It improves the crack resistance of road base materials, reduces the generation of dry shrinkage and thermal shrinkage cracks, enhances the durability of road bases, and extends the service life of roads. It improves the mechanical properties of road base materials, enhances their load-bearing and deformation resistance capabilities to better adapt to road traffic loads.

Claims

1. A supersulfate cement stabilized steel slag gravel base course material, characterized in that, The base material consists of the following materials by weight: 100 parts of aggregate, 3.5 - 6.0 parts of supersulphate cement, and 4.0 - 5.5 parts of water; among them, the aggregate consists of the following materials by weight percentage: 45 - 60% of limestone aggregate and 40 - 55% of steel slag aggregate; the supersulphate cement is desulphurized gypsum-based supersulphate cement, which consists of the following materials by weight: 70 - 80 parts of slag powder, 10 - 20 parts of dihydrate desulphurized gypsum, and 3 - 8 parts of Portland cement clinker.

2. The base material according to claim 1, characterized in that, The limestone aggregate has a particle size of 20 - 30 mm, 3 - 5 mm, or less than 3 mm, and the steel slag aggregate has a particle size of 5 - 10 mm or 10 - 20 mm.

3. The base material according to claim 1, characterized in that, The aggregate consists of the following materials by weight percentage : 21 - 28% of limestone aggregate with a particle size of 20 - 30 mm, 24 - 36% of steel slag aggregate with a particle size of 10 - 20 mm, 15 - 22% of steel slag aggregate with a particle size of 5 - 10 mm, 3 - 7% of limestone aggregate with a particle size of 3 - 5 mm, and 18 - 27% of limestone aggregate with a particle size of less than 3 mm.

4. The base material according to claim 1, characterized in that The steel slag aggregate is secondary-aged steel slag. The preparation method is to load the steel slag into a closed mold and introduce saturated steam and CO2 to obtain primary-aged steel slag, where the pressure in the closed container is not less than 0.5 MPa; then the primary-aged steel slag is naturally stacked at normal temperature and pressure for more than 6 months to obtain secondary-aged steel slag.

5. The base material according to claim 1, characterized in that, The slag powder is granulated blast furnace slag powder with a specific surface area of ≥ 400 m 2 / kg; the SO3 content in the gypsum dihydrate is ≥ 35%; the C3S content in the Portland cement clinker is ≥ 50%.

6. The base material according to claim 1, characterized in that, The steel slag is converter steel slag, and its chemical composition is 40 - 50% CaO, 10 - 15% SiO2, 15 - 25% FeO, and the free calcium oxide content is ≤ 3%.

7. A preparation method of the supersulphate cement stabilized steel slag and crushed stone base material according to claim 1, characterized in that, It includes the following steps: (1) Raw material preparation: Prepare the steel slag aggregate, screen and classify the steel slag aggregate and limestone aggregate according to the particle size requirements, and prepare the aggregate, supersulphate cement, and water in proportion. (2) Mixing and stirring: First, mix the steel slag aggregate and limestone aggregate evenly, add water and stir, and then add the supersulphate cement and continue to stir until evenly mixed.

8. The preparation method according to claim 7, characterized in that, In step (1), the preparation method of the supersulfate cement is as follows: mix slag powder, gypsum dihydrate, and Portland cement clinker in proportion, and then grind them to a specific surface area of ≥ 380 m 2 / kg to obtain the supersulfate cement.

9. Application of the supersulphate cement stabilized steel slag gravel base material described in claim 1 in the field of road engineering.

10. According to the application described in claim 9, the application is to spread and roll the mixture into shape, use a combination of double steel-wheel rollers and rubber-tyred rollers for rolling, and perform wet curing for 7 - 10 days under the conditions of 20 - 25 °C and humidity ≥ 93%.

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