Solid waste-based cementitious material with high interfacial bonding strength and preparation method thereof

Abstract

This invention provides a solid waste-based cementitious material with high interfacial bonding strength and its preparation method, relating to the field of cementitious material technology. The solid waste-based cementitious material, by weight, comprises the following raw materials: 40-45 parts steel slag, 8-12 parts calcium oxide, 1-2 parts sodium carbonate, 0.5-1 parts ferric p-toluenesulfonate, 6-8 parts modified desulfurization gypsum, 15-18 parts desulfurization ash, and 10-15 parts cement. The modified desulfurization gypsum is prepared by in-situ synthesis of nano-ferric phosphate on the surface of desulfurization gypsum using ammonium ferric phosphate, followed by modification of the nano-ferric phosphate-modified desulfurization gypsum with nano-aluminum carboxylate, resulting in a modified desulfurization gypsum co-modified with nano-ferric phosphate and nano-aluminum carboxylate. The steel slag is subjected to hot quenching, rod milling, magnetic separation, and grinding, and then mixed with calcium oxide, sodium carbonate, and ferric p-toluenesulfonate to form highly active steel slag micropowder. The solid waste-based cementitious material prepared by this invention exhibits high interfacial bonding strength and strong durability.

Description

Technical Field

[0001] This invention relates to the field of cementitious materials technology, specifically to a solid waste-based cementitious material with high interfacial bonding strength and its preparation method. Background Technology

[0002] Organic soft soils exhibit significant liquid limit characteristics due to humus adsorption, with their natural water content often approaching the liquid limit, placing them in a critical state of plastic flow. Their "three highs and three lows" characteristics (high water content, high void ratio, high compressibility; low strength, low permeability, and low consolidation coefficient) pose a severe challenge to engineering construction. Currently, widely used inorganic solidifying agents such as cement and lime exhibit defects in treating organic soft soils, including low solidification efficiency, poor environmental compatibility, and interfacial bonding failure, necessitating the development of new material systems to overcome these bottlenecks.

[0003] Against this backdrop, the resource utilization of industrial solid waste in the field of cementitious materials has become a core direction for the development of green building materials. Large quantities of industrial solid waste such as steel slag, desulfurization ash, and blast furnace slag, rich in silicon-aluminum active components, are widely explored for use as substitutes for cement clinker, achieving both resource recycling and significant reduction in carbon emissions. However, the development of such solid waste-based cementitious materials still faces a key technical bottleneck: insufficient interfacial bonding strength. In traditional processes, the utilization rate of active components in solid wastes such as steel slag and desulfurization ash is low, and the interface with substrates such as concrete and organic soft soil relies solely on physical filling, lacking chemical bonding force, resulting in weak mechanical properties of the solidified soil. Simultaneously, existing materials generally suffer from long setting times and insufficient durability, making it difficult to meet the demands of rapid construction and long-term service in engineering projects.

[0004] The prior art disclosed in CN119551916A is a multi-component solid waste-based auxiliary cementitious material and its preparation method. It utilizes microbial acidification to modify steel slag, carbide slag, and sintered red mud. Through the synergistic effect of solid waste and microbial acidification to modify the steel slag, a new model for the resource utilization of waste has been successfully established, realizing the transformation of waste into resources and significantly improving the carbon sequestration of steel slag. However, the prepared cementitious material exhibits poor interfacial adhesion, and the acidic environment of the steel slag after microbial acidification leads to increased interfacial porosity, resulting in poor stability.

[0005] The prior art disclosed in CN117105543B is a high-performance solid waste-based cementitious material and its preparation method. It uses slag, steel slag, industrial by-product gypsum, and photovoltaic silicon mud as raw materials, and activates the hydration of aluminate cement clinker with diethanolamine to generate ettringite and calcium aluminate gel, thus improving early strength. However, it mainly relies on aluminate cement clinker, resulting in a single interfacial bonding mechanism and low interfacial bond strength. Furthermore, this method has a long initial setting time, leading to low construction efficiency.

[0006] In summary, although the existing technical solutions have improved some properties of solid waste-based cementitious materials to a certain extent, the following technical problems still exist: low interfacial bonding strength, poor durability, and long setting time. Summary of the Invention

[0007] In order to solve the above-mentioned problems in the prior art, the present invention provides a solid waste-based cementitious material with high interfacial bonding strength and its preparation method, and achieves the following objectives: to prepare a solid waste-based cementitious material with high interfacial bonding strength, high durability and short setting time.

[0008] To achieve the above objectives, the following technical solution is adopted:

[0009] A solid waste-based cementitious material with high interfacial bonding strength, comprising the following raw materials by weight: 40-45 parts steel slag, 8-12 parts calcium oxide, 1-2 parts sodium carbonate, 0.5-1 parts ferric p-toluenesulfonate, 6-8 parts modified desulfurization gypsum, 15-18 parts desulfurization ash, and 10-15 parts cement.

[0010] The steel slag is liquid converter steel slag from the steel production process.

[0011] The modified desulfurized gypsum is prepared by in-situ synthesis of nano-iron phosphate on the surface of desulfurized gypsum using ammonium ferric phosphate, followed by modification of the desulfurized gypsum with nano-aluminum carboxylate, resulting in a modified desulfurized gypsum jointly modified with nano-iron phosphate and nano-aluminum carboxylate.

[0012] The desulfurization ash has the following composition: SiO2 content 50-51%, Al2O3 content 36-38%, CaO content 4-4.5%, and SO3 content 2-2.5%.

[0013] The cement is ordinary Portland cement P.O42.5.

[0014] This invention also provides a method for preparing a solid waste-based cementitious material with high interfacial bonding strength, the steps of which are as follows:

[0015] Step 1: Activation of steel slag

[0016] Pour the steel slag into the slag-curing tank, and then pour hot water at 70-80℃ into the bottom of the tank. The hot water should be poured at a flow rate of 5-8m. 3 The flow rate is continuously circulated at / h to maintain the internal temperature of the slag-curing tank at 150-200℃, and the curing time is 5-6 hours. After hot curing, the steel slag is crushed by a rod mill at a speed of 15-20 rpm for 30-40 minutes. After crushing, impurities are removed by a magnetic separator at a magnetic field strength of 100-150 mT, a drum speed of 10-15 rpm, and a magnetic separation time of 30-40 minutes. After magnetic separation, the slag is ground by a ball mill at a speed of 300-400 rpm for 30-40 minutes.

[0017] Calcium oxide, sodium carbonate, ferric p-toluenesulfonate, and pulverized steel slag are added to a twin-shaft mixer. The speed is set to 200-300 rpm and the mixing time is 10-15 minutes to form highly active steel slag powder.

[0018] Step 2: Nano-ferric phosphate modified desulfurized gypsum

[0019] Desulfurized gypsum was added to deionized water and stirred until homogeneous to prepare a desulfurized gypsum slurry with a mass concentration of 12-15%. Ferric ammonium phosphate solution was added to the desulfurized gypsum slurry at a mass ratio of (8-9):10, and stirred until homogeneous. Phosphoric acid was added to adjust the pH of the solution to 4.5-5.5, and the temperature was raised to 50-60℃. The stirring speed was 300-400 rpm, and the reaction was carried out for 1-1.5 hours. After the reaction, the solution was aged at room temperature for 12-16 hours, and then dried at 100-110℃ for 4-5 hours to obtain nano-ferric phosphate modified desulfurized gypsum. The purity of the desulfurized gypsum was ≥90%, and the particle size was 40-60 μm. The mass concentration of the ferric ammonium phosphate solution was 1-2%.

[0020] Step 3: Preparation of Modified Desulfurized Gypsum

[0021] Nano-alumina sol was uniformly mixed with oxalic acid at a mass ratio of 1:(2-3). The pH of the system was adjusted to 4-6 with ammonia. Then, ultrasonic dispersion was performed at a power of 500-600W for 20-30 minutes. Next, spray drying was carried out at an inlet air temperature of 150-160℃, an outlet air temperature of 80-90℃, and a feed rate of 5-10 mL / min. After drying, nano-aluminum carboxylate particles were obtained. The nano-alumina sol contained 20% alumina and had a particle size of 10-15 nm.

[0022] Nano-aluminum carboxylate particles were dissolved in deionized water to prepare a nano-aluminum carboxylate solution with a mass concentration of 1-1.2%. Sodium polyacrylate was added to the nano-aluminum carboxylate solution at a mass ratio of (0.5-1):100. The ultrasonic power was set to 500-550W and the ultrasonic time was 40-60min to form a suspension. Nano-ferric phosphate modified desulfurized gypsum was added to the suspension at a mass ratio of 1:(1-1.1). The stirring speed was 200-250rpm and the stirring time was 1-1.5h to obtain a mixture. The mixture was spray-dried at an inlet air temperature of 170-180℃, an outlet air temperature of 100-110℃, and a drying time of 40-60min to obtain modified desulfurized gypsum.

[0023] Step 4: Prepare solid waste-based cementitious materials

[0024] High-activity steel slag powder and modified desulfurized gypsum are poured into a forced mixer. The speed is set to 80-100 rpm, and the mixture is dry-mixed for 5-10 minutes. The speed is then adjusted to 50-60 rpm, and desulfurized ash is added to the mixer. The mixture is dry-mixed for another 3-5 minutes to obtain a mixed material. The mixer is then paused, and cement is evenly spread on the surface of the mixed material. The mixer is restarted, and the speed is restored to 80-100 rpm. The mixture is dry-mixed for another 5-10 minutes to obtain a solid waste-based cementitious material.

[0025] Mechanism of action of the present invention:

[0026] The activation process of steel slag enhances its activity through a synergistic effect of thermal activation, mechanical crushing, and chemical activation. Thermal quenching induces thermal expansion within the steel slag, disrupting the crystal structure of the mineral phases and increasing reactive sites. Rod milling, magnetic separation, and ball milling further increase the specific surface area of ​​the steel slag, improving its contact efficiency with other components. Calcium oxide, sodium carbonate, ferric p-toluenesulfonate, and the milled steel slag are mixed to form highly active steel slag micropowder. Calcium oxide provides calcium ions, while sodium carbonate, as an alkaline activator, reacts to activate the dissolution of active silica and alumina in the steel slag, generating hydrated calcium silicate, hydrated calcium aluminate, and other gelling substances. Ferric p-toluenesulfonate acts as a catalyst, accelerating the coordination reaction.

[0027] The surface of desulfurized gypsum is smooth, resulting in weak interfacial mechanical bonding with other cementing components. Ferric ammonium phosphate is used to synthesize nano-ferric phosphate in situ on the surface of desulfurized gypsum. Nano-ferric phosphate modification enhances its adhesion through surface modification and interfacial bridging, regulates crystal morphology, inhibits needle-like growth, and forms a finer, more uniform crystal structure. Nano-aluminum carboxylate further optimizes the surface properties of desulfurized gypsum based on ferric phosphate modification, utilizing the carboxyl groups of nano-aluminum carboxylate to chelate Ca on the gypsum surface. 2+ In conjunction with sodium polyacrylate, uniform dispersion is achieved; after mixing with the cementitious materials, the ferric phosphate on the surface of the modified gypsum can accelerate the nucleation of ettringite, and the nano-aluminum carboxylate complexes the hydrated Ca. 2+ It forms a dense interface layer, which has a dual effect of improving bonding strength and freeze-thaw resistance, and eliminating the weak layer of the interface transition zone that is common in traditional solid waste cementitious materials.

[0028] The beneficial effects of this invention are as follows:

[0029] (1) The solid waste-based cementitious material of the present invention has excellent interfacial bonding strength, with a 7-day compressive strength of 45.37-47.22 MPa and a 28-day compressive strength of 57.25-59.86 MPa; a 7-day flexural strength of 8.74-9.19 MPa and a 28-day flexural strength of 12.24-13.35 MPa.

[0030] (2) The solid waste-based cementitious material prepared in this invention is mixed with organic soft soil to form a solidified soil mixture. The unconfined compressive strength reaches 0.94-0.97 MPa in 7 days and 1.47-1.53 ​​MPa in 28 days.

[0031] (3) The solid waste-based cementitious material with high interfacial bonding strength of the present invention has the excellent characteristic of short setting time, with an initial setting time of 78-85 min and a final setting time of 137-149 min.

[0032] (4) The solid waste-based cementitious material of the present invention with high interfacial bonding strength has excellent durability and can withstand 291-302 freeze-thaw cycles; under 250 freeze-thaw cycles, the mass loss rate is 3.7-4.1%. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the present invention clearer, the embodiments of the present invention will be described in further detail below. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0034] Example 1: A solid waste-based cementitious material with high interfacial bonding strength and its preparation method

[0035] A solid waste-based cementitious material with high interfacial bonding strength, by weight, comprises the following raw materials: 40 parts steel slag, 8 parts calcium oxide, 1 part sodium carbonate, 1 part ferric p-toluenesulfonate, 6 parts modified desulfurization gypsum, 18 parts desulfurization ash, and 15 parts cement.

[0036] The steel slag is liquid converter steel slag from the steel production process.

[0037] The desulfurization ash has the following composition: SiO2 content 50-51%, Al2O3 content 36-38%, CaO content 4-4.5%, and SO3 content 2-2.5%.

[0038] The cement is ordinary Portland cement P.O42.5.

[0039] A method for preparing a solid waste-based cementitious material with high interfacial bonding strength, comprising the following steps:

[0040] Step 1: Activation of steel slag

[0041] The steel slag was poured into the slag-curing tank, and hot water at 70°C was injected into the bottom of the tank at a flow rate of 8m. 3The flow rate is continuously circulated at / h to maintain the internal temperature of the slag-curing tank at 150℃ for 6 hours. After hot curing, the steel slag is crushed by a rod mill at 15 rpm for 40 minutes. After crushing, impurities are removed by a magnetic separator at a magnetic field strength of 100 mT, a drum speed of 10 rpm, and a magnetic separation time of 40 minutes. After magnetic separation, the slag is ground by a ball mill at 300 rpm for 40 minutes.

[0042] Calcium oxide, sodium carbonate, ferric p-toluenesulfonate, and pulverized steel slag were added to a twin-shaft mixer, and the speed was set to 200 rpm for 15 minutes to form highly active steel slag powder.

[0043] Step 2: Nano-ferric phosphate modified desulfurized gypsum

[0044] Desulfurized gypsum was added to deionized water and stirred until homogeneous to prepare a 12% (w / w) desulfurized gypsum slurry. Ferric ammonium phosphate solution was added to the desulfurized gypsum slurry at a mass ratio of 8:10, and stirred until homogeneous. Phosphoric acid was added to adjust the pH to 4.5, and the solution was heated to 50°C with a stirring speed of 400 rpm for 1.5 hours. After the reaction, the solution was aged at room temperature for 12 hours, and then dried at 100°C for 5 hours to obtain nano-ferric phosphate modified desulfurized gypsum. The purity of the desulfurized gypsum was ≥90%, and the particle size was 40-60 μm. The mass concentration of the ferric ammonium phosphate solution was 1%.

[0045] Step 3: Preparation of Modified Desulfurized Gypsum

[0046] Nano-alumina sol was uniformly mixed with oxalic acid at a mass ratio of 1:2, and the pH of the system was adjusted to 4 with ammonia. Then, it was ultrasonically dispersed at 500W for 30 minutes. Following this, it was spray-dried at an inlet air temperature of 150℃, an outlet air temperature of 80℃, and a feed rate of 5mL / min. After drying, nano-aluminum carboxylate particles were obtained. The nano-alumina sol contained 20% alumina and had a particle size of 10-15nm.

[0047] Nano-aluminum carboxylate particles were dissolved in deionized water to prepare a 1% (w / w) nano-aluminum carboxylate solution. Sodium polyacrylate was added to the nano-aluminum carboxylate solution at a mass ratio of 0.5:100. The ultrasonic power was set to 500W and the ultrasonic time was 60min to form a suspension. Nano-ferric phosphate modified desulfurized gypsum was added to the suspension at a mass ratio of 1:1. The stirring speed was 200rpm and the stirring time was 1.5h to obtain a mixture. The mixture was then spray-dried at an inlet air temperature of 170℃ and an outlet air temperature of 100℃ for 60min to obtain modified desulfurized gypsum.

[0048] Step 4: Prepare solid waste-based cementitious materials

[0049] High-activity steel slag powder and modified desulfurized gypsum were poured into a forced mixer and dry-mixed for 10 minutes at a speed of 80 rpm. The speed was then adjusted to 50 rpm, and desulfurized ash was added to the mixer. The mixture was dry-mixed for another 5 minutes to obtain a final mixture. The mixer was then paused, and cement was evenly spread on the surface of the final mixture. The mixer was then restarted, and the speed was restored to 80 rpm. The mixture was dry-mixed for another 5 minutes to obtain a solid waste-based cementitious material.

[0050] Example 2: A solid waste-based cementitious material with high interfacial bonding strength and its preparation method

[0051] A solid waste-based cementitious material with high interfacial bonding strength, by weight, comprises the following raw materials: 40 parts steel slag, 10 parts calcium oxide, 1 part sodium carbonate, 1 part ferric p-toluenesulfonate, 8 parts modified desulfurization gypsum, 15 parts desulfurization ash, and 15 parts cement.

[0052] The steel slag is liquid converter steel slag from the steel production process.

[0053] The desulfurization ash has the following composition: SiO2 content 50-51%, Al2O3 content 36-38%, CaO content 4-4.5%, and SO3 content 2-2.5%.

[0054] The cement is ordinary Portland cement P.O42.5.

[0055] A method for preparing a solid waste-based cementitious material with high interfacial bonding strength, comprising the following steps:

[0056] Step 1: Activation of steel slag

[0057] The steel slag was poured into the slag-curing tank, and hot water at 70°C was injected into the bottom of the tank at a flow rate of 8m. 3 The flow rate is continuously circulated at / h to maintain the internal temperature of the slag-curing tank at 180℃ for 5 hours. After hot curing, the steel slag is crushed by a rod mill at 20 rpm for 40 minutes. After crushing, impurities are removed by a magnetic separator at a magnetic field strength of 150 mT, a drum speed of 15 rpm, and a magnetic separation time of 40 minutes. After magnetic separation, the slag is ground by a ball mill at 300 rpm for 40 minutes.

[0058] Calcium oxide, sodium carbonate, ferric p-toluenesulfonate, and pulverized steel slag were added to a twin-shaft mixer, and the speed was set to 300 rpm for 15 minutes to form highly active steel slag powder.

[0059] Step 2: Nano-ferric phosphate modified desulfurized gypsum

[0060] Desulfurized gypsum was added to deionized water and stirred until homogeneous to prepare a desulfurized gypsum slurry with a mass concentration of 14%. Ferric ammonium phosphate solution was added to the desulfurized gypsum slurry at a mass ratio of 8:10, and stirred until homogeneous. Phosphoric acid was added to adjust the pH of the solution to 5, and the temperature was raised to 55℃. The stirring speed was 350 rpm, and the reaction was carried out for 1.5 hours. After the reaction, the solution was aged at room temperature for 14 hours, and then dried at 110℃ for 4.5 hours to obtain nano-ferric phosphate modified desulfurized gypsum. The purity of the desulfurized gypsum was ≥90%, and the particle size was 40-60 μm. The mass concentration of the ferric ammonium phosphate solution was 1.5%.

[0061] Step 3: Preparation of Modified Desulfurized Gypsum

[0062] Nano-alumina sol was uniformly mixed with oxalic acid at a mass ratio of 1:3, and the pH of the system was adjusted to 5 with ammonia. Then, it was ultrasonically dispersed at 600W for 30 minutes. Following this, it was spray-dried at an inlet air temperature of 150℃, an outlet air temperature of 90℃, and a feed rate of 8mL / min. After drying, nano-aluminum carboxylate particles were obtained. The nano-alumina sol contained 20% alumina and had a particle size of 10-15nm.

[0063] Nano-aluminum carboxylate particles were dissolved in deionized water to prepare a 1.2% (w / w) nano-aluminum carboxylate solution. Sodium polyacrylate was added to the nano-aluminum carboxylate solution at a mass ratio of 1:100. The ultrasonic power was set to 500W and the ultrasonic time was 60min to form a suspension. Nano-ferric phosphate modified desulfurized gypsum was added to the suspension at a mass ratio of 1:1.1. The stirring speed was 250rpm and the stirring time was 1.5h to obtain a mixture. The mixture was then spray-dried at an inlet air temperature of 170℃ and an outlet air temperature of 100℃ for 60min to obtain modified desulfurized gypsum.

[0064] Step 4: Prepare solid waste-based cementitious materials

[0065] High-activity steel slag powder and modified desulfurized gypsum were poured into a forced mixer, and the speed was set to 80 rpm for dry mixing for 10 minutes. The speed was then adjusted to 60 rpm, and desulfurized ash was added to the mixer. The mixture was then dry mixed for another 3 minutes to obtain a mixture. The mixer was paused, and cement was evenly spread on the surface of the mixture. The mixer was restarted, and the speed was restored to 80 rpm for dry mixing for 10 minutes to obtain a solid waste-based cementitious material.

[0066] Example 3: A solid waste-based cementitious material with high interfacial bonding strength and its preparation method

[0067] A solid waste-based cementitious material with high interfacial bonding strength, by weight, comprises the following raw materials: 45 parts steel slag, 12 parts calcium oxide, 2 parts sodium carbonate, 0.5 parts ferric p-toluenesulfonate, 8 parts modified desulfurization gypsum, 15 parts desulfurization ash, and 10 parts cement.

[0068] The steel slag is liquid converter steel slag from the steel production process.

[0069] The desulfurization ash has the following composition: SiO2 content 50-51%, Al2O3 content 36-38%, CaO content 4-4.5%, and SO3 content 2-2.5%.

[0070] The cement is ordinary Portland cement P.O42.5.

[0071] A method for preparing a solid waste-based cementitious material with high interfacial bonding strength, comprising the following steps:

[0072] Step 1: Activation of steel slag

[0073] The steel slag was poured into the slag-curing tank, and hot water at 80°C was injected into the bottom of the tank at a flow rate of 5m. 3 The flow rate is continuously circulated at / h to maintain the internal temperature of the slag-curing tank at 200℃ for 5 hours. After hot curing, the steel slag is crushed by a rod mill at 20 rpm for 30 minutes. After crushing, impurities are removed by a magnetic separator at a magnetic field strength of 150 mT, a drum speed of 15 rpm, and a magnetic separation time of 30 minutes. After magnetic separation, the slag is ground by a ball mill at 400 rpm for 30 minutes.

[0074] Calcium oxide, sodium carbonate, ferric p-toluenesulfonate, and pulverized steel slag were added to a twin-shaft mixer, and the speed was set to 300 rpm for 10 minutes to form highly active steel slag powder.

[0075] Step 2: Nano-ferric phosphate modified desulfurized gypsum

[0076] Desulfurized gypsum was added to deionized water and stirred until homogeneous to prepare a 15% (w / w) desulfurized gypsum slurry. Ferric ammonium phosphate solution was added to the desulfurized gypsum slurry at a mass ratio of 9:10, and stirred until homogeneous. Phosphoric acid was added to adjust the pH to 5.5, and the solution was heated to 60°C with a stirring speed of 300 rpm for 1 hour. After the reaction, the solution was aged at room temperature for 16 hours, and then dried at 110°C for 4 hours to obtain nano-ferric phosphate modified desulfurized gypsum. The purity of the desulfurized gypsum was ≥90%, and the particle size was 40-60 μm. The mass concentration of the ferric ammonium phosphate solution was 2%.

[0077] Step 3: Preparation of Modified Desulfurized Gypsum

[0078] Nano-alumina sol was uniformly mixed with oxalic acid at a mass ratio of 1:3, and the pH of the system was adjusted to 6 with ammonia. Then, it was ultrasonically dispersed at 600W for 20 minutes. Following this, it was spray-dried at an inlet air temperature of 160℃, an outlet air temperature of 90℃, and a feed rate of 10mL / min. After drying, nano-aluminum carboxylate particles were obtained. The nano-alumina sol contained 20% alumina and had a particle size of 10-15nm.

[0079] Nano-aluminum carboxylate particles were dissolved in deionized water to prepare a 1.2% (w / w) nano-aluminum carboxylate solution. Sodium polyacrylate was added to the nano-aluminum carboxylate solution at a mass ratio of 1:100. The ultrasonic power was set to 550W and the ultrasonic time was 40min to form a suspension. Nano-ferric phosphate modified desulfurized gypsum was added to the suspension at a mass ratio of 1:1.1. The stirring speed was 250rpm and the stirring time was 1h to obtain a mixture. The mixture was then spray-dried at an inlet air temperature of 180℃ and an outlet air temperature of 110℃ for 40min to obtain modified desulfurized gypsum.

[0080] Step 4: Prepare solid waste-based cementitious materials

[0081] High-activity steel slag powder and modified desulfurized gypsum were poured into a forced mixer, and the speed was set to 100 rpm for 5 minutes of dry mixing. The speed was then adjusted to 60 rpm, and desulfurized ash was added to the mixer. The mixture was then dry mixed for another 3 minutes to obtain a mixture. The mixer was paused, and cement was evenly spread on the surface of the mixture. The mixer was restarted, and the speed was restored to 100 rpm for 5 minutes of dry mixing to obtain a solid waste-based cementitious material.

[0082] Comparative Example 1

[0083] A solid waste-based cementitious material, by weight, comprises the following raw materials: 40 parts steel slag, 8 parts modified desulfurization gypsum, 15 parts desulfurization ash, and 15 parts cement.

[0084] The steel slag is liquid converter steel slag from the steel production process.

[0085] The desulfurization ash has the following composition: SiO2 content 50-51%, Al2O3 content 36-38%, CaO content 4-4.5%, and SO3 content 2-2.5%.

[0086] The cement is ordinary Portland cement P.O42.5.

[0087] A method for preparing a solid waste-based cementitious material, comprising the following steps:

[0088] Step 1: Steel Slag Pretreatment

[0089] The steel slag is poured into a water tank to cool it down, with the water temperature controlled at 20-40℃. After cooling, the cooled steel slag blocks are fed into a crusher for simple crushing. After crushing, the blocks are fed into a ball mill for grinding at 300 rpm for 40 minutes to obtain raw steel slag powder.

[0090] Step 2: Nano-ferric phosphate modified desulfurized gypsum

[0091] This step is the same as the "nano-ferric phosphate modified desulfurized gypsum" step in Example 2.

[0092] Step 3: Preparation of Modified Desulfurized Gypsum

[0093] This step is the same as the "Preparation of Modified Desulfurized Gypsum" step in Example 2.

[0094] Step 4: Prepare solid waste-based cementitious materials

[0095] The high-activity steel slag powder was replaced with virgin steel slag powder, and the remaining operations were the same as the "Preparation of solid waste-based cementitious material" steps in Example 2.

[0096] Comparative Example 2

[0097] A solid waste-based cementitious material, by weight, comprises the following raw materials: 40 parts steel slag, 10 parts calcium oxide, 1 part sodium carbonate, 1 part ferric p-toluenesulfonate, 8 parts desulfurized gypsum, 15 parts desulfurized ash, and 15 parts cement.

[0098] The steel slag is liquid converter steel slag from the steel production process.

[0099] The desulfurization ash has the following composition: SiO2 content 50-51%, Al2O3 content 36-38%, CaO content 4-4.5%, and SO3 content 2-2.5%.

[0100] The desulfurized gypsum has a purity of ≥90% and a particle size of 40-60μm.

[0101] The cement is ordinary Portland cement P.O42.5.

[0102] A method for preparing a solid waste-based cementitious material, comprising the following steps:

[0103] Step 1: Activation of steel slag

[0104] This step is the same as the "Steel Slag Activation" step in Example 2.

[0105] Step 2: Prepare solid waste-based cementitious materials

[0106] The modified desulfurized gypsum was replaced with desulfurized gypsum, and the remaining operations were the same as the "Preparation of solid waste-based cementitious material" steps in Example 2.

[0107] Example 4 Performance Testing

[0108] (a) The solid waste-based cementitious materials prepared in Examples 1-3 and Comparative Examples 1-2 were mixed, stirred, molded, and cured according to the test methods provided in GB / T 17671-2021. The specimens were prisms of 40mm×40mm×160mm. The flexural strength and compressive strength properties of the specimens were tested after curing for 7 days and 28 days. The specific test results are shown in Table 1.

[0109] Table 1

[0110]

[0111] As shown in Table 1, the solid waste-based cementitious materials prepared in Examples 1-3 exhibit a 7-day compressive strength of 45.37-47.22 MPa and a 28-day compressive strength of 57.25-59.86 MPa; a 7-day flexural strength of 8.74-9.19 MPa and a 28-day flexural strength of 12.24-13.35 MPa. These high compressive and flexural strengths demonstrate that the solid waste-based cementitious materials prepared in this invention possess excellent interfacial bonding strength.

[0112] (ii) The initial setting time and final setting time of the solid waste-based cementitious materials prepared in Examples 1-3 and Comparative Examples 1-2 were tested according to the test methods provided in GB / T 1346-2024. The specific test results are shown in Table 2.

[0113] Table 2

[0114]

[0115] As shown in Table 2, the solid waste-based cementitious materials prepared in Examples 1-3 have shorter initial and final setting times, with an initial setting time of 78-85 min and a final setting time of 137-149 min. Therefore, the solid waste-based cementitious materials prepared in this invention have the excellent characteristic of short setting time.

[0116] (III) The solid waste-based cementitious materials prepared in Examples 1-3 and Comparative Examples 1-2 were subjected to durability tests according to the test methods provided in GB / T 50082-2024; the mass loss rate was detected under the condition of 250 freeze-thaw cycles. The specific test results are shown in Table 3.

[0117] Table 3

[0118]

[0119] As shown in Table 3, the solid waste-based cementitious materials prepared in Examples 1-3 have a freeze-thaw cycle resistance of 291-302 cycles, which is significantly improved compared to the comparative example. The solid waste-based cementitious materials prepared in Examples 1-3 exhibit a mass loss rate of 3.7-4.1% after 250 freeze-thaw cycles. The high freeze-thaw cycle resistance and low mass loss rate demonstrate that the solid waste-based cementitious materials prepared in this invention possess excellent durability.

[0120] (iv) The solid waste-based cementitious materials prepared in Examples 1-3 and Comparative Examples 1-2 were mixed with organic soft soil to prepare a solidified soil mixture. Unconfined compressive strength tests were conducted according to the test methods provided in JGJ / T 233-2011. Specific test results are shown in Table 4. Sample preparation: The solid waste-based cementitious material and organic soft soil were added to a mixer at a mass ratio of 1:8, with a stirring speed of 200 rpm and a stirring time of 20 min; then water was added and stirred at a water-to-solid waste-based cementitious material ratio of 1:1.25, with a stirring speed of 600 rpm and a stirring time of 5 min to obtain the solidified soil mixture. A 70.7mm×70.7mm×70.7mm cubic mold was used. The solidified soil mixture was added to the mold, compacted by tamping and vibrating on a vibrating table, and then covered with a plastic film. The specimen and mold were placed in a standard constant temperature and humidity curing chamber at a curing temperature of 20±1℃ and a curing humidity of ≥95% for 48 hours. After curing, the specimen was demolded, wrapped and sealed with plastic film, and then placed in the curing chamber to cure for the specified age. The organic matter content of the soft soil was 8-10%, and the natural moisture content was 52-55%.

[0121] Table 4

[0122]

[0123] As shown in Table 4, the 7-day unconfined compressive strength of the solidified soil mixtures prepared in Examples 1-3 and Comparative Examples 1-2 reached 0.94-0.97 MPa; the 28-day unconfined compressive strength reached 1.47-1.53 ​​MPa. This indicates that the solid waste-based cementitious material prepared in this invention significantly improves the mechanical properties of solidified organic soft soil, providing an efficient and environmentally friendly solution for engineering construction in organic soft soil areas; it further demonstrates that the solid waste-based cementitious material prepared in this invention possesses excellent interfacial bond strength.

[0124] Obviously, there are many other possible implementation methods under the concept of this invention. It should be stated here that any changes made under the inventive concept of this invention will fall within the protection scope of this invention.

Claims

1. A solid waste-based cementitious material with high interfacial bonding strength, characterized in that: The solid waste-based cementitious material, by weight, comprises the following raw materials: 40-45 parts steel slag, 8-12 parts calcium oxide, 1-2 parts sodium carbonate, 0.5-1 parts ferric p-toluenesulfonate, 6-8 parts modified desulfurization gypsum, 15-18 parts desulfurization ash, and 10-15 parts cement. The modified desulfurized gypsum is prepared by in-situ synthesis of nano-iron phosphate on the surface of desulfurized gypsum using ammonium iron phosphate, followed by modification of the nano-iron phosphate-modified desulfurized gypsum with nano-aluminum carboxylate, resulting in a modified desulfurized gypsum jointly modified with nano-iron phosphate and nano-aluminum carboxylate. The steel slag is heated, rod-milled, magnetically separated, and ground before being mixed with calcium oxide, sodium carbonate, and ferric p-toluenesulfonate to form highly active steel slag micro powder.

2. The method for preparing a solid waste-based cementitious material with high interfacial bonding strength according to claim 1, characterized in that: The process includes the following steps: steel slag activation, preparation of nano-ferric phosphate modified desulfurized gypsum, preparation of modified desulfurized gypsum, and preparation of solid waste-based cementitious materials. The steel slag activation involves pouring steel slag into a slag-curing tank, with the internal temperature of the slag-curing tank being 150-200℃ and the curing time being 5-6 hours. After hot curing, the steel slag is successively subjected to rod milling, magnetic separation, and grinding. Calcium oxide, sodium carbonate, ferric p-toluenesulfonate, and the ground steel slag are mixed and stirred to form highly active steel slag micro powder.

3. The method for preparing a solid waste-based cementitious material with high interfacial bonding strength according to claim 2, characterized in that: In the steel slag activation step, the following steps are involved: rod mill: control the rod mill speed to 15-20 rpm, and the crushing time to 30-40 min; magnetic separation: control the magnetic field strength of the magnetic separator to 100-150 mT, the drum speed to 10-15 rpm, and the magnetic separation time to 30-40 min; grinding: control the ball mill speed to 300-400 rpm, and the grinding time to 30-40 min.

4. The method for preparing a solid waste-based cementitious material with high interfacial bonding strength according to claim 2, characterized in that: The nano-ferric phosphate modified desulfurized gypsum is prepared by adding ferric ammonium phosphate solution to desulfurized gypsum slurry and stirring until homogeneous; adding phosphoric acid to adjust the pH of the solution to 4.5-5.5 and reacting; after the reaction is completed, aging at room temperature for 12-16 hours and then drying to obtain nano-ferric phosphate modified desulfurized gypsum.

5. The method for preparing a solid waste-based cementitious material with high interfacial bonding strength according to claim 4, characterized in that: The reaction is carried out at a temperature of 50-60℃ for 1-1.5 hours; the mass concentration of the ferric ammonium phosphate solution is 1-2%; and the mass concentration of the desulfurized gypsum slurry is 12-15%.

6. The method for preparing a solid waste-based cementitious material with high interfacial bonding strength according to claim 4, characterized in that: In the step of modifying desulfurized gypsum with nano-ferric phosphate, the mass ratio of ammonium ferric phosphate solution to desulfurized gypsum slurry is (8-9):

10.

7. The method for preparing a solid waste-based cementitious material with high interfacial bonding strength according to claim 4, characterized in that: Preparation of the modified desulfurized gypsum: Sodium polyacrylate is added to a nano-aluminum carboxylate solution and ultrasonically dispersed to form a suspension; desulfurized gypsum modified with nano-ferric phosphate is poured into the suspension and stirred to obtain a mixture; the mixture is spray-dried to obtain the modified desulfurized gypsum.

8. The method for preparing a solid waste-based cementitious material with high interfacial bonding strength according to claim 7, characterized in that: The ultrasonic dispersion is set to an ultrasonic power of 500-550W and an ultrasonic time of 40-60min; the mass concentration of the nano-aluminum carboxylate solution is 1-1.2%; the spray drying is set to an inlet air temperature of 170-180℃, an outlet air temperature of 100-110℃, and a drying time of 40-60min.

9. The method for preparing a solid waste-based cementitious material with high interfacial bonding strength according to claim 7, characterized in that: In the preparation steps of the modified desulfurized gypsum, the mass ratio of sodium polyacrylate to nano-aluminum carboxylate is (0.5-1):100; the mass ratio of the nano-ferric phosphate modified desulfurized gypsum to the suspension is 1:(1-1.1).

10. The method for preparing a solid waste-based cementitious material with high interfacial bonding strength according to claim 2, characterized in that: The solid waste-based cementitious material is prepared by: pouring high-activity steel slag powder and modified desulfurization gypsum into a forced mixer, setting the speed to 80-100 rpm, and dry mixing for 5-10 minutes; adjusting the speed to 50-60 rpm, adding desulfurization ash to the mixer, and continuing to dry mix for 3-5 minutes to obtain a mixture; adding cement, setting the speed to 80-100 rpm, and dry mixing for 5-10 minutes to obtain the solid waste-based cementitious material.

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