Marine corrosion-resistant cementing material based on metallurgical solid waste and composite mineralization activator and preparation method of marine corrosion-resistant cementing material

Abstract

The invention belongs to the technical field of building materials, and discloses a marine corrosion-resistant cementing material based on metallurgical solid waste and a composite mineralization activator and a preparation method thereof.The marine corrosion-resistant cementing material is prepared from, by mass, 60-89% of metallurgical solid waste powder, 10-38% of the composite mineralization activator and 0-3% of auxiliary components. The marine corrosion-resistant cementing material provided by the invention takes the metallurgical solid waste powder as a main raw material, so that efficient resource utilization of metallurgical solid wastes is realized, dependence on natural resources is reduced, the problem of environmental pollution caused by solid waste stockpiling is reduced, and the marine corrosion-resistant cementing material has good environmental protection benefits and economic benefits. The marine corrosion-resistant cementing material has the properties of low hydration heat, high strength, excellent chloride ion permeation resistance, freezing and thawing resistance, chemical corrosion resistance and the like, is particularly suitable for severe environments such as marine engineering and the like, and can effectively prolong the service life of an engineering structure and reduce the maintenance cost.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of building materials, and relates to a marine corrosion-resistant cementitious material based on metallurgical solid waste and a composite mineralization activator and a preparation method thereof, in particular to a marine environment corrosion-resistant cementitious material using metallurgical industrial solid waste (manganese steel slag, red mud and nickel-iron slag) as main raw materials and activated by a composite mineralization activator and a preparation method thereof. The material is suitable for concrete structure engineering in seawater erosion environment, including but not limited to seawall revetment, cross-sea bridge pile foundation, offshore wind power foundation, port wharf and deep-sea drilling platform and other harsh corrosion environments. BACKGROUND

[0002] Marine engineering concrete is long-term exposed to high-salt and high-humidity environment, and faces the dual degradation mechanisms of chloride ion penetration and sulfate attack. Studies have shown that Cl - penetrates into the interior of concrete through capillary pores, and when the Cl - concentration exceeds the critical threshold (0.6-0.9 kg / m 3 ), it will cause the rupture of the passivation film to cause corrosion expansion, and SO4 2- reacts with cement hydration products to generate expansive ettringite (3CaO·Al2O3·3CaSO4·32H2O), which aggravates the cracking of the structure. The chloride ion diffusion coefficient of traditional Portland cement is generally higher than 5×10 -12 m 2 / s, and the sulfate attack strength loss rate is more than 30% at 180 days, which is difficult to meet the long-term life design requirements of cross-sea bridges.

[0003] Existing improvement technologies mainly adopt two types of schemes: one is to mix 30-50% of slag powder and add sodium sulfate activator, which reduces the chloride ion diffusion coefficient to 3.2×10 -12 m 2 / s, but still needs more than 40% of cement clinker, and the cost increases by 45% due to the purity requirement of industrial sodium sulfate; the other is to use red mud-based cementitious material, but needs to add 10% of nano-SiO2 to improve the activity, which increases the production cost by 2000 yuan / ton, and also has the problem of volume instability caused by free alkali metal ions.

[0004] In the existing metallurgical solid waste utilization technology, although the compounding scheme can realize a high solid waste content, it is difficult to synergistically activate multiple elements such as iron and magnesium due to the limitation of simple superposition of calcium-silicon-aluminum components, resulting in insufficient compressive strength and limited impermeability of the material. The difference in chemical composition between steel slag and red mud easily causes the structure of the hydration product to be loose, the porosity to be high, and the chloride ion diffusion coefficient to be at a high level. The adaptability of traditional activators to multiple components is insufficient, and a large amount of unreacted active components remain, not only causing resource waste, but also causing post-volume expansion problems, further aggravating pore coarsening and harmful ion penetration. Such materials face durability bottlenecks in the harsh environment of the deep sea, and are difficult to meet long-term service requirements.

[0005] Therefore, it is urgent to develop a new type of cementing material, which can realize high content (≥60%) of metallurgical solid waste, and break through the contradiction between impermeability, volume stability and cost control of existing materials through multi-component synergistic activation technology, to meet the harsh durability requirements of marine engineering. SUMMARY

[0006] The purpose of the present application is to solve the problems of low utilization rate of existing metallurgical solid waste and insufficient marine corrosion resistance, and to provide a marine corrosion-resistant cementing material based on metallurgical solid waste and a composite mineralization activator and a preparation method thereof, to solve the technical defects of poor impermeability, insufficient volume stability and high cost of traditional materials.

[0007] The present application adopts the following technical scheme: A marine corrosion-resistant cementing material based on metallurgical solid waste and a composite mineralization activator, the raw materials for preparing the marine corrosion-resistant cementing material are as follows: the sum of the mass percentages of each component is 100%, including metallurgical solid waste powder 60-89%, composite mineralization activator 10-38% and auxiliary components 0-3%; first, the metallurgical solid waste powder is added to a stirring device, an appropriate amount of water is added, then the composite mineralization activator is added, the auxiliary components are added after stirring uniformly, and then an appropriate amount of water is added for the second time, and the mixture is uniformly mixed, the total amount of water added is 40-60% of the sum of the masses of each component.

[0008] Preferably, the metallurgical solid waste powder includes manganese steel slag powder, red mud, and nickel-iron slag, and the mass ratio of the three is (3-5):(2-4):1.

[0009] Preferably, the specific surface area of the metallurgical solid waste powder is ≥500 m² / kg, the CaO content of the manganese steel slag powder is ≥40%, the Fe2O3 content of the red mud is ≥15%, and the MgO content of the nickel-iron slag is 8-12%.

[0010] Preferably, the composite mineralization activator is compounded by calcining calcium mirabilite and calcining alunite at a mass ratio of (1.5-2):1, the calcining temperature is 600-700°C, and the calcining time is 1-2 hours.

[0011] Further, the calcined calcium glauberite is natural calcium glauberite calcined at 650 DEG C, and the effective content of sulfate is greater than or equal to 85%.

[0012] Preferably, the auxiliary component comprises borax and hydroxypropyl methyl cellulose ether, and the mass ratio is (0.5-1.5):(0.3-1.5).

[0013] Further, the mass ratio of the manganese steel slag powder and the red mud is 3:2, and the nickel-iron slag content is 10-15% of the total solid waste mass.

[0014] According to the marine corrosion-resistant cementing material provided by the embodiment of the present application, the composite mineralization activator is added with 1-2% of the total mass of the composite mineralization activator.

[0015] The preparation method of the marine corrosion-resistant cementing material provided by the embodiment of the present application comprises the following steps: 60-89% of the metallurgical solid waste powder, 10-38% of the composite mineralization activator and 0-3% of the auxiliary component are taken by mass percentage, the metallurgical solid waste powder is compounded by the manganese steel slag powder, the red mud and the nickel-iron slag according to the mass ratio of (3-5):(2-4):1, and the composite mineralization activator is compounded by the calcined calcium glauberite and the calcined alunite according to the ratio of (1.5-2):1.

[0016] The specific preparation method comprises: First, the metallurgical solid waste powder is added into a stirring device, and then appropriate amount of water is added, followed by the addition of the composite mineralization activator, the auxiliary component is added after uniform stirring, and the stirring is performed at a speed of 70-100 r / min for 10-20 minutes, then appropriate amount of water is added again, and the mixing is continued until uniform, the stirring is continued at a speed of 70-100 r / min for 5-10 minutes, and the total amount of water added is 40-60% of the sum of the mass of each component.

[0017] Compared with the prior art, the marine corrosion-resistant cementing material provided by the embodiment of the present application has the following beneficial effects: The marine corrosion-resistant cementing material provided by the application takes metallurgical solid waste powder as the main raw material, realizes efficient resource utilization of metallurgical solid waste, reduces the dependence on natural resources, reduces environmental pollution caused by solid waste storage, and has good environmental and economic benefits. By reasonably proportioning manganese slag powder, red mud and nickel-iron slag, and controlling the specific surface area and chemical composition thereof, a synergistic effect is generated between the metallurgical solid waste powders, which provides a good cementing property basis for the cementing material. The composite mineralization activator is prepared by compounding calcined calcium mirabilite and calcined alunite treated under specific proportions and calcination conditions, and adding nano-aluminum oxide, which effectively activates the activity of the metallurgical solid waste powder, improves the hydration reaction speed and degree of the cementing material, and thus enhances the early and late strength of the material. The reasonable matching of borax and hydroxypropyl methyl cellulose ether in the auxiliary component further improves the workability and durability of the cementing material. The marine corrosion-resistant cementing material has low hydration heat, high strength, excellent resistance to chloride ion penetration, freeze-thaw resistance, chemical corrosion resistance and other properties, and is particularly suitable for harsh environments such as marine engineering, can effectively prolong the service life of the engineering structure, and reduce the maintenance cost.

[0018] 1、The marine corrosion-resistant cementing material of the application has high strength and long-term anti-permeability, and the compressive strength is ≥55MPa after seawater curing for 90 days, the chloride ion diffusion coefficient is ≤1.5×10 -12 m 2 / s, the strength loss rate is <5% after 150 freeze-thaw cycles, significantly improving the durability of marine engineering structures and reducing maintenance costs.

[0019] 2、The composite mineralization activator of the application synergistically activates the Ca, Fe and Al multi-element activity in the manganese slag and red mud, forms a tobermorite and layered double hydroxide (Mg-Al-Cl LDHs) composite structure, and the chloride ion binding rate is ≥70%, effectively inhibiting steel bar corrosion, with an early strength of 50MPa at 28 days and no late shrinkage.

[0020] 3、The application replaces more than 60% of traditional cement raw materials with metallurgical solid waste, reduces limestone consumption by 1.2 tons per ton of material, reduces CO2 emissions by 75%, and reduces production costs by 20-30% compared with ordinary Portland cement, with environmental protection and economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a scanning electron microscope image of the material when the MgO content is 8-12%; Figure 2 is a scanning electron microscope image of the material when the MgO content is >12%. DETAILED DESCRIPTION

[0022] The technical solutions described in the present application are further specifically described below in combination with examples. For the sake of convenience in description, all alternative technical features and embodiments contained in the present application cannot be exhaustively listed, and therefore, any technical feature and embodiment in the examples should be known by those skilled in the art that the protection scope of the present application includes any alternative technical feature and embodiment taken by those skilled in the art without creative labor. Specifically, any technical feature in the present application or any combination of two or more technical features provided by the present application should be within the protection scope of the present application. If the specific techniques and conditions are not mentioned in the examples, the techniques and conditions described in the literature in the art or according to the product manual are used, and if the manufacturers of the reagents or instruments are not mentioned, the reagents or instruments are conventional products that can be commercially available. Manganese steel slag powder refers to a powder material obtained by grinding the waste slag generated in the process of smelting manganese alloy steel or high manganese steel. It is mainly derived from the Electric Arc Furnace (EAF) or Basic Oxygen Furnace (BOF) smelting process of the steel industry. When smelting manganese alloy steel, a certain amount of metallic manganese or manganese-iron alloy is added as an alloying element to achieve the required mechanical properties of the steel grade (such as high strength, high toughness, and wear resistance). The floating slag and molten slag generated during smelting mainly contain calcium silicate, iron-manganese oxide, etc. After cooling, crushing, magnetic separation (to recover scrap iron), and then grinding to a specified fineness, manganese steel slag powder is obtained.

[0023] Compared with traditional steel slag, manganese steel slag has certain particularity in mineral composition and activity due to the presence of a large amount of manganese oxide (MnO, etc.). The present application utilizes the characteristic of being rich in CaO (≥40%) as the main source of calcium and alkaline activation conditions, and the manganese and iron elements in it can also participate in the reaction under the action of the composite activator, which has a positive effect on the formation of a dense microstructure.

[0024] Nickel-iron slag, also known as nickel slag, is an industrial waste slag generated in the process of producing ferronickel using the RKEF (Rotary Kiln-Electric Furnace) process, i.e., the "rotary kiln-mine heat furnace" method. This process is the mainstream technology for the current fire smelting of laterite nickel ore. The specific process is as follows: the laterite nickel ore with high water content is dried and pre-reduced in a rotary kiln, and then sent to a mine heat furnace for high-temperature smelting. The nickel and part of the iron in the ore are reduced and fused into a ferronickel liquid, while the gangue components (such as SiO2, MgO, CaO, Al2O3) in the ore react with flux to form molten slag that floats up and is separated from the metal liquid, and then forms nickel-iron slag after water quenching (granulation) or air cooling.

[0025] Red soil nickel ore is rich in magnesium itself, so a significant feature of nickel-iron slag is that it contains a relatively high content of MgO (usually 8%-20%). In the present application, nickel-iron slag with a MgO content of 8-12% is specifically selected, aiming to utilize its MgO component. In the presence of sulfate and aluminate provided by the composite activator, MgO can participate in the formation of, for example, magnesium aluminate spinel (MgAl2O4) or more importantly layered double hydroxides (LDHs, such as Mg-Al-Cl LDH). The LDH structure can effectively "capture" and solidify the chloride ions in the environment, which is one of the key mechanisms for obtaining extremely low chloride ion diffusion coefficients in the present application, thereby solving the stability problems that MgO may cause in traditional materials and turning harm into benefit.

[0026] The manganese steel slag powder of the present application needs to meet the specific surface area ≥500 m² / kg, and the content of CaO ≥40%. A high specific surface area can increase the contact area with the activator, accelerate the reaction, optimize the pore structure, and synergistically improve the impermeability with nano-Al2O3. A high CaO content can provide an alkaline environment and help the formation of ettringite to support the early strength of ≥50 MPa at 28 days, and can also avoid the late strength reduction. The content of Fe2O3 in red mud is ≥15%, which can be converted into iron cementing phase under the action of the composite activator to improve the compactness (frozen-thaw loss rate <5%), Fe 3+ can complex with chloride ions (binding rate ≥70%) and react with nickel-iron slag MgO to form Mg-Fe-Al LDHs to resist seawater corrosion (strength > 58 MPa); the MgO content of nickel-iron slag needs to be controlled at 8-12%, which is a necessary condition for the formation of Mg-Al-Cl LDHs, and can prevent swelling or insufficient formation. The LDHs nanosheet layer can also penetrate the ettringite network to block cracks, so that the strength of the cementitious material reaches 65 MPa at 10 months. Traditional cement has no such structure, and the chloride ion diffusion coefficient is much higher.

[0027] The mixing sequence of the present application cannot be reversed. In related processes, the sequence of "first adding metallurgical solid waste powder, then adding composite mineralization activator, and finally adding auxiliary components" needs to be followed, and each step has a clear scientific purpose. First, adding metallurgical solid waste powder is to establish an alkaline environment with pH > 12.5, dissolve Ca 2+ , SiO4 4- ions, and lay the foundation for subsequent activation reactions. If the sequence is reversed, the activator will directly contact the liquid phase, which will cause local over-reaction and generate amorphous products to block active sites. For example, when the sequence of Example 2 is reversed, the 28-day strength decreases by 9.8%. 2- The composite mineralization activator added next can make the calcined glauberite (providing SO4 3+ ) and calcined alunite (providing Al 2+ ) gradually release ions in the alkaline medium, and react with the dissolved Ca 2+The activator needs to contain 1-2% of premixed nano-alumina in its mass to ensure that the nanoparticles are preferentially dispersed in the system and avoid being wrapped by solid waste; among the auxiliary components added at the end, borax can form [B4O5(OH)4] in a high alkaline environment 2- The complex prolongs the initial setting time of C3A in the manganese slag from 5 minutes to 45 minutes, and the HPMC needs to be added at the later stage of ion release to prevent the chain from curling and causing a 50% loss of viscosity when the temperature is greater than 40 DEG C.

[0028] As shown in Figure 1 The application controls the MgO content of the nickel-iron slag to be 8-12%, and in the sulfate and aluminate environment provided by the composite activator, the MgO and Ca 2+ , Al 3+ cooperate to generate Mg-Al-Cl LDHs layered double hydroxide, which has a typical sheet morphology and can effectively capture and solidify chloride ions, with a chloride ion combination rate of greater than or equal to 70%; as shown in Figure 2 When the MgO content of the nickel-iron slag exceeds 12% (such as the MgO content of 15% in Comparative Example 3-3), a stable LDHs sheet structure cannot be formed, the micro-porosity significantly increases, resulting in a loss of 18% in compressive strength and a decrease in impermeability. At the same time, the 1-2% nano-alumina added in the composite mineralization activator can act as a crystal nucleus to promote the crystallization and growth of LDHs and improve the structural stability. If the nano-alumina is not added (Comparative Example 4-1), the chloride ion diffusion coefficient increases to 2.7 x 10 -12 m² / s.

[0029] In the following examples, the amount of water is not strictly required, and can be adjusted according to the actual situation during implementation. The total amount of water is 40-60% of the sum of the mass of each component of the cementitious material. Example 1

[0030] (1) Raw material preparation Metallurgical solid waste powder: 50% (mass percentage) of manganese slag powder (CaO content 42%, specific surface area 520 m² / kg), 20% (mass percentage) of red mud (Fe2O3 content 16%, specific surface area 510 m² / kg), and 10% (mass percentage) of nickel-iron slag (MgO content 10%, specific surface area 530 m² / kg) are mixed uniformly. The total mass of the metallurgical solid waste powder accounts for 80%.

[0031] Composite mineralization activator: natural glauber salt is calcined at 650 DEG C for 1.5 hours to obtain calcined glauber salt with a sulfate effective content of 86%, which is then compounded with calcined alunite calcined at 650 DEG C for 1.5 hours at a mass ratio of 1.8:1, and 1.5% of nano-alumina is added. The mass of the composite mineralization activator accounts for 18.7%.

[0032] Auxiliary components: borax 0.8% (mass percentage) and hydroxypropyl methylcellulose ether 0.5% (mass percentage) were weighed, the mass ratio was 1.6:1, and the mass percentage of auxiliary components was 1.3%. (2) The preparation process is as follows: The above prepared 80% metallurgical solid waste powder was added to a stirring device, an appropriate amount of water was added, and stirring was carried out at a speed of 80 r / min for 5 minutes; then 18.7% of the composite mineralization activator was added, and stirring was continued at a speed of 80 r / min for 5 minutes; finally, 1.3% of the auxiliary component was added, and stirring was carried out at a speed of 80 r / min for 15 minutes; then an appropriate amount of water was added, and stirring was continued at a speed of 80 r / min for 8 minutes, and the mixture was uniformly mixed to obtain the marine corrosion-resistant cementitious material.

[0033] (3) Performance test: ① The hydration heat of the marine corrosion-resistant cementitious material was tested according to the dissolution heat method in GB / T 12959-2008 "Cement Hydration Heat Determination Method".

[0034] ② The flexural strength and compressive strength of the marine corrosion-resistant cementitious material after 3 days and 28 days of curing in seawater were tested according to GB / T17671-1999 "Cement Mortar Strength Test Method (ISO Method)" (now GB / T17671-2021), and the compressive strength after 3 months and 10 months of curing in seawater was recorded; ③ The freeze-thaw test of the marine corrosion-resistant cementitious material was carried out according to the method in GB / T50082-2009 "Standard for Long-term Performance and Durability Test Methods of Ordinary Concrete", and the compressive strength loss rate after 150 freeze-thaw cycles was determined.

[0035] ④ The chloride ion diffusion coefficient of the marine corrosion-resistant cementitious material was tested according to the rapid chloride ion migration coefficient method (RCM method) in GB / T50082-2009 "Standard for Long-term Performance and Durability Test Methods of Ordinary Concrete".

[0036] ⑤ According to GB / T17671-1999 "Cement Mortar Strength Test Method (ISO Method)" (now GB / T17671-2021), test blocks were prepared, and alkali corrosion resistance test was carried out in a 5% sodium hydroxide solution, and the compressive strength was tested after 3 months; ⑥ According to GB / T17671-1999 "Cement Mortar Strength Test Method (ISO Method)" (now GB / T17671-2021), test blocks were prepared, and sulfate corrosion resistance test was carried out in a 5% sodium sulfate solution, and the compressive strength was tested after 3 months.

[0037] (4) The test results are as follows: 3-day hydration heat <180 kJ / kg; 7-day hydration heat < 210 kJ / kg; Seawater 3-day flexural strength: 5.8 MPa; Seawater 28-day flexural strength: 8.1 MPa; Seawater 3-day compressive strength: 29.4 MPa; Seawater 28-day compressive strength: 53.0 MPa; Seawater 3-month compressive strength: 59.5 MPa; Seawater 10-month compressive strength: 65.0 MPa; Chloride ion diffusion coefficient: 1.3 x 10 -12 m² / s; 150-cycle freeze-thaw compressive strength loss rate: 4.6%; 3-month alkali corrosion resistance compressive strength: 58.5 MPa; 3-month sulfate corrosion resistance compressive strength: 59.8 MPa. Example 2

[0038] (1) Raw material preparation Metallurgical solid waste powder: manganese slag powder 30% (mass percentage) (CaO content 43%, specific surface area 500 m² / kg), red mud 20% (mass percentage) (Fe2O3 content 18%, specific surface area 520 m² / kg), nickel-iron slag 10% (mass percentage) (MgO content 9%, specific surface area 550 m² / kg), total proportion 60%.

[0039] Composite mineralization activator: calcined glauberite (calcined at 650°C for 2 hours, sulfate content 85%) and calcined alunite compounded at 1.5:1, with 1% nano-alumina added, total proportion 37%.

[0040] Auxiliary component: borax 1.5% (mass percentage) + hydroxypropyl methylcellulose ether 1.5% (mass percentage) (ratio 1.5:1), total proportion 3%.

[0041] (2) According to the modified preparation method of Example 1, first add metallurgical solid waste powder and stir for 5 minutes, then add appropriate amount of water, then add composite mineralization activator and stir for 5 minutes, finally add auxiliary component and stir for 15 minutes, then add appropriate amount of water and continue stirring for 8 minutes, to prepare the marine corrosion-resistant cementitious material.

[0042] According to the above raw material composition, change the mixing order to "first add composite mineralization activator, then add metallurgical solid waste powder, and finally add auxiliary component", and the rest of the preparation conditions are the same as Example 1, and the 28-day compressive strength is 47.8 MPa, which is 9.8% lower than 53 MPa of Example 1, verifying the technical effect that the mixing order cannot be reversed.

[0043] Performance test was carried out based on the performance test method of Example 1.

[0044] The test results are as follows: 3-day hydration heat < 180 kJ / kg; 7-day hydration heat < 210 kJ / kg; Seawater 3-day flexural strength: 7.1 MPa; Seawater 28-day flexural strength: 11.5 MPa; Seawater 3-day compressive strength: 28.9 MPa; Seawater 28-day compressive strength: 47.8 MPa; Seawater 3-month compressive strength: 55.9 MPa; Seawater 10-month compressive strength: 61.4 MPa; Chloride ion diffusion coefficient: 1.4 x 10 -12 m² / s; After 10 months of maintenance in seawater, the steel bar had no rust and no weight loss; 150-cycle freeze-thaw compressive strength loss rate: 4.7%; 3-month alkali corrosion-resistant compressive strength: 55.7 MPa; 3-month sulfate corrosion-resistant compressive strength: 56.2 MPa. Example 3

[0045] This example provides a marine corrosion-resistant cementitious material composed of the following mass fractions of raw materials: (1) Raw material preparation Metallurgical solid waste powder: manganese slag powder 45% (mass percentage) (CaO content 41%, specific surface area 540 m² / kg), red mud 30% (mass percentage) (Fe2O3 content 17%, specific surface area 500 m² / kg), nickel-iron slag 14% (mass percentage) (MgO content 11%, specific surface area 510 m² / kg), total ratio 89%.

[0046] Composite mineralization activator: calcined glauber's salt (calcined at 700°C for 1 hour) and calcined alunite are compounded at a ratio of 2:1, and 2% nano alumina is added, with a total ratio of 10%.

[0047] Auxiliary components: borax 0.5% (mass percentage) + hydroxypropyl methylcellulose ether 0.5% (mass percentage) (ratio 1:1), total ratio 1%.

[0048] (2) The marine corrosion-resistant cementitious material is prepared according to the preparation method of Example 1.

[0049] Performance test was carried out based on the performance test method of Example 1.

[0050] 3-day hydration heat < 180 kJ / kg; 7-day hydration heat < 210 kJ / kg; Seawater 3-day flexural strength: 5.6 MPa; Seawater 28-day flexural strength: 8.9 MPa; Seawater 3-day compressive strength: 27.3 MPa; Seawater 28-day compressive strength: 51.5 MPa; Seawater 3-month compressive strength: 58.0 MPa; Seawater 10-month compressive strength: 63.4 MPa; Chloride ion diffusion coefficient: 1.4 x 10 -12 m² / s; After 10 months of maintenance in seawater, the steel bar is free of rust and the weight is not lost; 150-cycle freeze-thaw compressive strength loss rate: 4.9%; 3-month alkali corrosion resistance compressive strength: 57.8 MPa; 3-month seawater corrosion resistance compressive strength: 58.2 MPa.

[0051] Comparative Example 1 This comparative example provides an ordinary portland cement, which is purchased from the ordinary portland cement P.O. 52.5 produced by Dalian Tianrui Cement Co., Ltd.

[0052] Performance tests are carried out based on the performance test method of Example 1.

[0053] Test results: 3-day hydration heat > 250 kJ / kg; 7-day hydration heat > 300 kJ / kg; Seawater 3-day flexural strength: 5.2 MPa; Seawater 28-day flexural strength: 8.7 MPa; Seawater 3-day compressive strength: 25.0 MPa; Seawater 28-day compressive strength: 47.3 MPa; Seawater 3-month compressive strength: 44.3 MPa; Seawater 10-month compressive strength: 40.4 MPa; Chloride ion diffusion coefficient: 8.3 x 10 -12 m² / s.

[0054] Compared with Comparative Example 1 (ordinary portland cement), the marine corrosion-resistant cementitious material of Example 1 has the following advantages: 1. Lower hydration heat: The 3-day hydration heat of Example 1 is <180 kJ / kg, and the 7-day hydration heat is <210 kJ / kg; while the 3-day hydration heat of Comparative Example 1 is >250 kJ / kg, and the 7-day hydration heat is >300 kJ / kg. Lower hydration heat helps to reduce the risk of cracking in mass concrete due to temperature stress, and improves the durability of concrete.

[0055] 2. Improved early compressive strength: The 3-day seawater compressive strength of Example 1 is 29.4 MPa, higher than the 25.0 MPa of Comparative Example 1, indicating that the material of Example 1 can form strength faster in the early stage, which is beneficial to shorten the construction period and improve engineering efficiency.

[0056] 3. Continuous growth and higher later compressive strength: The 28-day seawater compressive strength of Example 1 is 53.0 MPa, the 90-day compressive strength is 59.5 MPa, and the 10-month compressive strength is 65.0 MPa; the 28-day seawater compressive strength of Comparative Example 1 is 47.3 MPa, the 90-day compressive strength is 44.3 MPa, and the 10-month compressive strength is 40.4 MPa. The material of Example 1 has a significant growth in later strength, and is much higher than that of Comparative Example 1, indicating that it has better long-term mechanical properties and durability.

[0057] 4. Good flexural strength performance: Although the 28-day flexural strength of Comparative Example 1 (8.7 MPa) is slightly higher than that of Example 1 (8.1 MPa), the 3-day flexural strength of Example 1 (5.8 MPa) is higher than that of Comparative Example 1 (5.2 MPa), and in the overall strength growth trend, the strength of Example 1 is more balanced and stable.

[0058] 5. Lower chloride ion diffusion coefficient: The chloride ion diffusion coefficient of Example 1 is 1.3 x 10 -12 m 2 / s, which is much lower than the 8.3 x 10 -12 m 2 / s of Comparative Example 1. A lower chloride ion diffusion coefficient means that the material of Example 1 has better resistance to the penetration of chloride ions, which can effectively prevent steel corrosion and improve the durability of concrete structures in marine environments.

[0059] 6. Better frost resistance: The compressive strength loss rate of Example 1 after 150 cycles of freeze-thaw is 4.6%, while Comparative Example 1 does not mention this data, but generally, ordinary Portland cement has relatively poor frost resistance. The lower compressive strength loss rate of Example 1 indicates that it has better freeze-thaw resistance and is suitable for marine engineering in cold regions.

[0060] 7. Good chemical corrosion resistance: the compressive strength of Example 1 was 58.5 MPa after 3 months of alkali corrosion test in a 5% sodium hydroxide solution, and 59.8 MPa after 3 months of sulfate corrosion test in a 5% sodium sulfate solution, indicating that the material has good resistance to chemicals such as alkali and sulfate, and can maintain stable performance in complex marine chemical environment.

[0061] Comparative Example 2: Single solid waste component test (verify the necessity of compounding) Table 1 Raw material composition and key index detection data table of Example 1 and Comparative Example 2

[0062] Conclusion: Single solid waste cannot balance strength formation (CaO), impermeability (Fe2O3) and ion solidification (MgO).

[0063] Comparative Example 3: Threshold test of key components (verify the critical point of content) Table 2 Raw material composition and key index detection data table of Example 1 and Comparative Example 3

[0064] Comparative Example 4: Modifier modification comparison test (verify the effect of nano aluminum oxide) Table 3 Raw material composition and key index detection data table of Example 1 and Comparative Example 4

[0065] Comparative Example 5: Auxiliary component function verification test Table 4 Raw material composition and key index detection data table of Example 1 and Comparative Example 5

[0066] The above only describes the preferred embodiments of the present application, and does not limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A marine corrosion resistant cementitious material based on metallurgical solid waste and complex mineralization activator, characterized in that, The raw material for preparing the marine corrosion-resistant cementitious material comprises, in percentage by mass, 60-89% of metallurgical solid waste powder, 0-38% of composite mineralization activator, and 0-3% of auxiliary component, with the sum of the percentages of the components being 100%; the metallurgical solid waste powder is first added into a stirring device, an appropriate amount of water is added, the composite mineralization activator is then added, the auxiliary component is added after uniform stirring, and an appropriate amount of water is added for the second time, followed by uniform mixing, with the total amount of water being 40-60% of the sum of the masses of the components.

2. The metallurgical solid waste and complex mineralization activator based marine corrosion resistant cementitious material as claimed in claim 1, wherein, The metallurgical solid waste powder comprises manganese steel slag powder, red mud, and nickel-iron slag, with the mass ratio of the three being (3-5):(2-4):

1.

3. The metallurgical solid waste and complex mineralization activator based marine corrosion resistant cementitious material as claimed in claim 2, wherein, The specific surface area of the metallurgical solid waste powder is greater than or equal to 500 m² / kg, the CaO content of the manganese steel slag powder is greater than or equal to 40%, the Fe2O3 content of the red mud is greater than or equal to 15%, and the MgO content of the nickel-iron slag is 8-12%.

4. The metallurgical solid waste and complex mineralization activator based marine corrosion resistant cementitious material as claimed in claim 1, wherein, The composite mineralization activator is prepared by compounding calcined glauber's salt and calcined alunite at a mass ratio of (1.5-2):1, with the calcining temperature being 600-700°C and the calcining time being 1-2 hours.

5. The metallurgical solid waste and complex mineralization activator based marine corrosion resistant cementitious material as claimed in claim 4, wherein, The calcined glauber's salt is natural glauber's salt calcined at a temperature of 600-750°C, with the effective content of sulfate being greater than or equal to 85%.

6. The metallurgical solid waste and complex mineralization activator based marine corrosion resistant cementitious material as claimed in claim 1, wherein, The auxiliary component comprises borax and hydroxypropyl methyl cellulose ether, with the mass ratio being (0.5-1.5):(0.3-1.5).

7. The metallurgical solid waste and complex mineralization activator based marine corrosion resistant cementitious material as claimed in claim 2, wherein, The mass ratio of the manganese steel slag powder to the red mud is 3:2, and the nickel-iron slag accounts for 10-15% of the total solid waste.

8. The metallurgical solid waste and complex mineralization activator based marine corrosion resistant cementitious material as claimed in claim 4, wherein, 1-2% of nano-aluminum oxide is added to the composite mineralization activator, with the amount of the nano-aluminum oxide being 1-2% of the total mass of the composite mineralization activator.

9. A method of producing a marine corrosion resistant cementitious material as claimed in any one of claims 1 to 8, characterised in that, The method comprises the following steps: 60-89% of metallurgical solid waste powder, 10-38% of composite mineralization activator, and 0-3% of auxiliary component are mixed in the following order: the metallurgical solid waste powder is first added into a stirring device, an appropriate amount of water is added, the composite mineralization activator is then added, the auxiliary component is added after uniform stirring, and the stirring is continued at a speed of 70-100 r / min for 10-20 minutes, and then an appropriate amount of water is added for the second time, followed by uniform mixing, to obtain the cementitious material.

10. The method for preparing the marine corrosion-resistant cementitious material according to claim 9, characterized in that, The uniform mixing after the second addition of water refers to stirring at a speed of 70-100 r / min for 5-10 minutes.

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