Steel slag-based cementing material for improving characteristics of stabilized soil by adopting efficient carbonization

Abstract

The invention discloses a steel slag-based cementing material for improving stability and durability of stabilized soil by adopting an efficient carbonization technology. The steel slag-based cementing material comprises a main curing agent, a reinforcing agent and an exciting agent. The main curing agent is steel slag in ferrous metallurgy solid waste, the reinforcing agent is a reinforcing agent A, and the exciting agent is an exciting agent A. The cementing material system shows engineering performance superior to that of traditional cement and lime after being cured, is suitable for road subgrade construction, can realize large-scale resource utilization of the steel slag, and achieves the environment-friendly purpose of treating waste with waste. Meanwhile, the material can significantly improve the stability of the solidified soil and reduce the strength loss of the solidified soil after dry-wet cycle and freeze-thaw cycle, has good durability, and has the dual effects of improving the stability and durability of the solidified soil.

Description

Technical Field

[0001] This invention relates to the field of soft soil solidification treatment and utilization, specifically to a steel slag-based cementitious material that uses efficient carbonization to improve the properties of solidified soil. Background Technology

[0002] With the rapid development of infrastructure construction, the over-reliance on natural resources and high carbon emissions of traditional cementing materials (such as cement and lime) are becoming increasingly prominent. Meanwhile, the steel metallurgical industry generates large amounts of solid waste, such as steel slag, which accumulates into mountains, occupying land and polluting the environment. Using steel slag to replace cement in the preparation of soil stabilization materials can alleviate resource pressure and achieve the resource utilization of solid waste, aligning with the direction of green and low-carbon development.

[0003] Although steel slag has a similar chemical composition to cement and possesses potential cementitious activity, its practical application still faces three major technical bottlenecks: first, its low activity index leads to insufficient cementitious performance; second, its poor volume stability easily causes later cracking; and third, its poor grindability results in excessively high processing energy consumption.

[0004] Steel slag suffers from low activity, poor volume stability, and poor grindability, resulting in low early strength and insufficient durability in practical applications. Although existing technologies such as mechanical grinding, alkali activation, and carbonization enhancement have improved the performance of steel slag to some extent, a systematic solution for high-volume, high-performance steel slag-based cementitious materials is still lacking. Summary of the Invention

[0005] The purpose of this invention is to provide a high-content steel slag-based cementitious material that synergistically enhances its activity, stability, and durability through efficient carbonization technology. This material uses steel slag as the main curing agent, supplemented with reinforcing agent A and activator A, and is prepared through a specific ratio and process. It has advantages such as high curing efficiency, good stability, and strong durability, and is suitable for road base courses, water-stabilized layers, and other engineering projects.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a steel slag-based cementitious material that improves the properties of solidified soil through efficient carbonization, comprising a cementitious material system consisting of the following components by mass percentage: (i) Steel slag: 45%–50%; (ii) Reinforcing agent A: 25%–30%; (iii) Invigorator A: 15%–20%; The dosage of each component is a percentage of its mass relative to the total mass of the cementitious material;

[0007] Furthermore, the particle size of the steel slag is divided into 50–100 mesh (H grade), 100–150 mesh (F grade) and greater than 200 mesh (G grade).

[0008] A method for preparing the steel slag-based cementitious material as described in claim 1, comprising the following steps: (1) Mix steel slag powder and reinforcing agent A in proportion and stir at 300 r / min for 3 minutes; (2) Mix the above mixture with activator A and stir at 300 r / min for 3 minutes to obtain a gelling material.

[0009] Compared with existing technologies, the steel slag-based cementitious material using high-efficiency carbonization technology provided by this invention has the following significant advantages: Resource conservation and environmental protection, turning waste into treasure: using steel slag as the main raw material (accounting for 45%-50%), it greatly consumes industrial solid waste, reduces cement dependence and carbon emissions, and is in line with the goal of green and low-carbon development.

[0010] High strength and good water stability: The unconfined compressive strength of the solidified soil exceeds 3MPa, and the water stability coefficient is higher than 100%. Its performance is superior to traditional materials, and it fully meets the strength and stability requirements of road subgrade.

[0011] Significantly enhanced durability: After multiple wet-dry and freeze-thaw cycles, the strength loss is far less than that of conventional materials, demonstrating excellent resistance to environmental degradation and extending the service life of engineering projects.

[0012] Excellent volume stability: Through composition and control technology, the problem of late-stage expansion and cracking caused by free calcium oxide is effectively suppressed, ensuring the long-term safety and stability of the project.

[0013] Low cost and easy to promote: The main raw material is industrial waste residue, which is widely available and low in cost. The production process is simple, and it has good economic benefits and large-scale application prospects. Attached Figure Description

[0014] Figure 1 Unconfined compressive strength of solidified soil prepared from H-grade steel slag; Figure 2 Unconfined compressive strength of solidified soil prepared from Grade F steel slag; Figure 3 Unconfined compressive strength of solidified soil prepared from G-grade steel slag; Figure 4 The effect of wet-dry cycles on the strength of solidified soil; Figure 5 The effect of freeze-thaw cycles on the strength of solidified soil; Figure 6 : Water swelling rate of solidified soil; Figure 7 The effect of carbonization time on unconfined compressive strength; Figure 8 The effect of carbonization treatment on freeze-thaw performance. Detailed Implementation

[0015] In the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0016] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0017] The present invention will now be described in detail with reference to specific embodiments, including: Example 1

[0018] In this embodiment, the mixing ratio of the steel slag-based solidification modifier is: 50% steel slag, 30% reinforcing agent A, and 20% activator A. The three materials are mixed evenly and set aside. The original soil and solidifier are placed in a mixing pot and mixed evenly for 5 minutes. The mixture is then discharged, and the solidified material is pressed into cylindrical specimens with dimensions of Φ50*50mm using a testing machine. Standard curing is performed, and the engineering performance test results are shown in Table 1. The specimens are cured by soaking in water for 6 days and 1 day, with the water level 2cm above the specimen and spaced 2cm apart. After soaking for 1 day, the specimens are removed and the surface moisture is wiped clean. Then, the two sets of specimens are tested for unconfined compressive strength. The physicochemical performance test results are shown in Table 1. Example 2

[0019] In this embodiment, the mixing ratio of the steel slag-based solidification and modification material is: steel slag 50%, reinforcing agent A 30%, and activator A 20%. The three materials are mixed evenly and set aside. The original soil and solidifying agent are placed in a mixing pot and mixed evenly for 5 minutes. The mixture is then discharged, and the solidified material is pressed into cylindrical specimens with a diameter of Φ50*50mm using a testing machine. Standard curing is performed, and the engineering performance test results of the solidified soil specimens prepared based on three different particle sizes of steel slag are shown in [the table below]. Figure 1 , Figure 2 , Figure 3 . Example 3

[0020] In this embodiment, the mixing ratio of the steel slag-based solidification and modification material is: 50% steel slag, 30% reinforcing agent A, and 20% activator A. The three materials are mixed evenly and set aside. The original soil and solidifying agent are placed in a mixing pot and mixed evenly for 5 minutes. The mixture is then discharged, and the solidified material is pressed into cylindrical specimens with a diameter of Φ50*50mm using a testing machine. Standard curing is performed, and specimens cured for 28 days are dried at 70℃ for 12 hours, then immersed in a constant temperature water bath at approximately 22℃ for 12 hours. This constitutes one cycle. The unconfined compressive strength is recorded after 3, 5, 7, 9, 11, and 13 cycles. The changes in the unconfined compressive strength of the solidified soil are also recorded. The physicochemical performance test results are shown below. Figure 4 . Example 4

[0021] In this embodiment, the mixing ratio of the steel slag-based solidification modifier is: 50% steel slag, 30% reinforcing agent A, and 20% activator A. These three materials are mixed evenly and set aside. The original soil and solidifier are placed in a mixing pot and mixed evenly for 5 minutes. The mixture is then discharged, and the solidified material is pressed into cylindrical specimens (Φ50*50mm) using a testing machine. Standard curing is performed, with specimens spaced approximately 2cm apart in sealed bags. After 27 days of curing, the specimens are removed and soaked in water for 1 day, with the water level approximately 2.5cm above the top of the specimen. After soaking, the specimens are removed and wiped dry. The mass of the specimen at this point is m0. A freeze-thaw cycle is then placed in a -18℃ low-temperature chamber, with a 2cm gap between each specimen to allow for airflow. After freezing for 16 hours, the specimens are removed, weighed, and immediately placed in a 20℃ water bath for thawing, with the water level 2cm above the specimen. The thawing time is 8 hours. After thawing, the specimens are removed and dried. The mass of the specimen at this point is mn, thus completing one freeze-thaw cycle. The physicochemical performance test results are shown below. Figure 5 . Example 5

[0022] In this embodiment, the mixing ratio of the steel slag-based solidification modifier is: 50% steel slag, 30% reinforcing agent A, and 20% activator A. The three materials are mixed evenly and set aside. The original soil and solidifier are placed in a mixing pot and mixed evenly for 5 minutes. The mixture is then discharged, and the solidified material is pressed into cylindrical specimens with dimensions of Φ50*50mm using a testing machine. The prepared soil sample is pushed out from the ring cutter and placed on a porous plate. The measuring plate is placed above the specimen, the dial gauge is adjusted, and the initial reading is recorded. Based on the indoor temperature and expansion rate, T represents the dial gauge reading at 0h, 1h, 3h, 5h, 7h, 15h, 24h, 36h, 48h, and 72h. The physicochemical performance test results are shown below. Figure 6 . Example 6

[0023] In this embodiment, the mixing ratio of the steel slag-based solidification modifier is: 50% steel slag, 30% reinforcing agent A, and 20% activator A. The three materials are mixed evenly and set aside. The mixed solidified material is then pressed into cylindrical specimens (Φ50*50mm) using a testing machine. The prepared solidified soil is then cured for 7 days under standard conditions, followed by different carbonization times: 2h, 24h, and 72h. The solidified soil cured for 7 days and 2h carbonization is then cured to 166h under standard conditions, followed by 2h carbonization in a carbonization chamber. The solidified soil cured for 7 days and 24h carbonization is cured to 144h under standard conditions, followed by 24h carbonization in a carbonization chamber. After carbonization, the unconfined compressive strength of the solidified soil specimens is tested. The physicochemical performance test results are shown below. Figure 7 . Example 7

[0024] In this embodiment, the mixing ratio of the steel slag-based solidification modifier is: 50% steel slag, 30% reinforcing agent A, and 20% activator A. The three materials are mixed evenly and set aside. The mixed solidified material is then pressed into cylindrical specimens with dimensions of Φ50*50mm using a testing machine. The prepared solidified soil is then cured for 7 days under standard conditions, followed by different carbonization times: 2h, 24h, and 72h. The solidified soil cured for 7 days and 2h carbonization is then cured to 166h under standard conditions, followed by 2h carbonization in a carbonization chamber. The solidified soil cured for 7 days and 24h carbonization is then cured to 144h under standard conditions, followed by 24h carbonization in a carbonization chamber. After carbonization, freeze-thaw cycle tests are performed on the 28-day-old solidified soil and the standard solidified soil, referencing the unconfined compressive strength of the solidified soil specimens. The physicochemical performance test results are shown below. Figure 8 .

[0025]

[0026] The present invention discloses a steel slag-based cementitious material system for solidification prepared from steel slag powder treated with carbonization technology. The proportions of various components are strictly designed, and each plays an important role, resulting in the following advantages and effects.

[0027] The solidification material used in this invention undergoes a chemical reaction when mixed with soil. By controlling the free calcium oxide content to be less than 2%, volume stability can be guaranteed.

[0028] In this invention, steel slag-based cementitious materials are mixed with soil. The hydrated calcium silicate produced by the hydration of the reinforcing material and the reaction of steel slag pozzolanic fills the pores and binds the soil particles, thereby enhancing the compressive strength of the soil skeleton and improving the overall compressive strength of the solidified soil.

[0029] The steel slag-based cementitious material provided in this invention improves the stability and durability of solidified soil. It has high strength and stability, which can meet the requirements of roadbed soil for material strength and stability in road construction. At the same time, the leachate has low soluble salt content, which meets the requirements of greening soil for physical and chemical properties. Furthermore, the harmless utilization of waste resources such as steel slag in iron and steel metallurgy solid waste is a low-cost, green, and sustainable economic development approach that uses waste to treat waste.

[0030] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of the present invention, and the present invention is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also considered to be within the scope of protection of the present invention.

Claims

1. A steel slag-based cementitious material that improves the properties of solidified soil through efficient carbonization, characterized in that, The cementitious material system consists of the following components by mass percentage: (i) Steel slag: 45%–50%; (ii) Reinforcing agent A: 25%–30%; (iii) Invigorator A: 15%–20%; The dosage of each component is a percentage of its mass relative to the total mass of the cementitious material; 2. The steel slag-based cementitious material for improving the properties of solidified soil by high-efficiency carbonization according to claim 1, characterized in that: The steel slag is classified into three particle sizes: 50–100 mesh (H grade), 100–150 mesh (F grade), and greater than 200 mesh (G grade).

3. A method for preparing the steel slag-based cementitious material as described in claim 1, comprising the following steps: (1) Mix steel slag powder and reinforcing agent A in proportion and stir at 300 r / min for 3 minutes; (2) Mix the above mixture with activator A and stir at 300 r / min for 3 minutes to obtain a gelling material.

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