Slag-based cementing material and preparation method thereof

Abstract

The invention relates to the technical field of cementing materials, in particular to a slag-based cementing material and a preparation method thereof.The slag-based cementing material comprises a main material and an alkaline activator, and the main material further comprises granulated blast-furnace slag powder, industrial byproduct gypsum, concrete waste, tailings and carbide slag; the alkaline activator comprises any one or more of kiln dust, plant ash and slaked lime, and further comprises sodium hydroxide and boric acid; the weight ratio of the main material to the alkaline activator is 100: (0.5-5); the alkaline activator can effectively control the setting time, and meanwhile, the alkaline activator and the main materials are subjected to synergistic reaction to form a C-S-H gel and ettringite double-network structure, so that the compressive strength and durability of the gel material are greatly improved, and the expansion rate of colloid is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of cementitious materials, and particularly relates to a slag-based cementitious material and a preparation method thereof. Background Art

[0002] The long-term storage of industrial waste residues requires a large amount of land. Especially the accumulation of mining waste rocks and bulk industrial solid wastes not only occupies land resources but may also damage the original ecological system. However, the utilization of solid wastes has great potential in carbon emission reduction. By using solid waste resources such as industrial waste residues, through chemical reactions, CO2 is converted into stable carbonate minerals to make gel materials, realizing the permanent sequestration of carbon. At the same time, the solid wastes are converted into high-value-added products, which have broad application prospects in fields such as construction engineering, road engineering, water conservancy engineering, underground engineering, and environmental protection engineering.

[0003] However, in the prior art, sodium hydroxide or water glass is often used as the alkaline activator for preparing the cementitious material. However, a single-component alkaline activator is not convenient for effectively controlling the reaction rate and hardening rate. Strong alkalis (such as sodium hydroxide) rapidly destroy the vitreous structure of slag, releasing a large amount of active SiO2 and Al2O3, resulting in a violent polycondensation reaction, producing a large amount of gel in a short time, but at the same time forming more disordered porous structures, reducing the later strength and having poor durability. The fixed modulus of water glass limits the reaction regulation. A single-modulus water glass is difficult to meet the activity requirements of different slags. A single-component sodium hydroxide or water glass will also introduce too many alkali metal ions (such as Na + 、K + ), which may cause alkali-aggregate reaction in the long term, resulting in the expansion or cracking of the gel material.

[0004] Therefore, the present application provides a slag-based cementitious material and a preparation method thereof to solve the problems raised in the above background art. Summary of the Invention

[0005] The purpose of the present invention is to provide a slag-based cementitious material and a preparation method thereof, to solve the problems that the existing alkaline activator has a single component, is difficult to meet the activity requirements of different slags, resulting in reduced strength of the later-stage colloid and poor durability.

[0006] To solve the above technical problems, the present invention provides a slag-based cementitious material, including a main material and an alkaline activator. The main material further includes granulated blast furnace slag powder, industrial by-product gypsum, concrete waste, tailings, and carbide slag. The alkaline activator includes any one or more of kiln dust, plant ash, and slaked lime, and the alkaline activator further includes sodium hydroxide and boric acid. The weight ratio of the main material to the alkaline activator is 100:0.5 - 5.

[0007] A further improvement of the technical solution of the present invention lies in that: the alkaline activator, by weight, consists of 0-30 parts of kiln dust, 0-20 parts of plant ash, 0-50 parts of slaked lime, 30-50 parts of sodium hydroxide, and 0.1-1 part of boric acid, with a moisture content of 2-5% and a specific surface area ≥ 400 m² / kg.

[0008] A further improvement of the technical solution of the present invention lies in that: it includes a main material. By weight, the main material includes the following raw materials: 45-65 parts of granulated blast furnace slag powder, 5-20 parts of industrial by-product gypsum, 10-50 parts of concrete waste, 0-10 parts of tailings, 0-3 parts of carbide slag, with a moisture content of 2-5% and a specific surface area ≥ 400 m² / kg.

[0009] A further improvement of the technical solution of the present invention lies in that: by weight percentage, the kiln dust contains 35-45% CaO, 40-48% SiO2, 7-11% Al2O3, 6-10% K2O + Na2O, 0.5-10% ZnO, 0-1% SrO, with a loss on ignition of 1-3% and a moisture content of 2-5%.

[0010] A further improvement of the technical solution of the present invention lies in that: by weight percentage, the chemical composition of the granulated blast furnace slag powder is: 45-48% CaO, 23-26% SiO2, 9-12% Al2O3, 5-7% MgO, 2-3% SO3, 0.5-1.5% K2O + Na2O, 1-2.5% Fe2O3, with a loss on ignition of 1-3%.

[0011] A further improvement of the technical solution of the present invention lies in that: by weight percentage, the chemical composition of the industrial by-product gypsum is 29-31% CaO, 1-4% SiO2, 2-4% Al2O3, 0.5-2% MgO, 50-54% SO3, 1.5-3% Fe2O3, with a loss on ignition of 4.5-6%.

[0012] A further improvement of the technical solution of the present invention lies in that: by weight percentage, the chemical composition of the concrete waste is: 39-41% CaO, 45-52% SiO2, 1-2% Al2O3, 1-2.5% MgO, 1.5-3% SO3, 0.1-0.4% Fe2O3, with a loss on ignition of 1.0-3.5%.

[0013] A further improvement of the technical solution of the present invention lies in that: by weight percentage, the chemical composition of the tailings is: 4-6% CaO, 53-56% SiO2, 9-12% Al2O3, 1.5-3.8% MgO, 2-3% SO3, 2-4% K2O + Na2O, 4-7% Fe2O3, with a loss on ignition of 8-14%.

[0014] A further improvement of the technical solution of the present invention lies in that: by weight percentage, the chemical composition of carbide slag is: 60-65% CaO, 1-3% SiO2, 1.5-3.5% Al2O3, 0.5-2% SO3, and the loss on ignition is 24-30%.

[0015] A preparation method of a slag-based cementitious material includes the following steps: Step 1: Weigh kiln ash, plant ash, slaked lime, sodium hydroxide, and boric acid in a determined proportion, and mix them in a mixer for 5-10 minutes to obtain an alkaline activator.

[0016] Step 2: Weigh granulated blast furnace slag powder, industrial by-product gypsum, concrete waste, tailings, carbide slag, and alkaline activator in a determined proportion. After mixing evenly, enter a vertical mill and grind for 2-10 minutes.

[0017] Step 3: Separate with a powder separator to screen out particles with a specific surface area ≥ 400 m² / kg.

[0018] Step 3: Collect and bag. If the fineness requirement is not met, return it to the mill for grinding again; the qualified finished product is carried into a bag filter by gas, and the gas and material are separated through the bag.

[0019] Adopting the above technical solution, the present invention has the following beneficial effects: 1. The slag-based cementitious material and its preparation method provided by the present invention. The alkaline activator is prepared by compounding kiln ash, quicklime, slaked lime, sodium hydroxide, and boric acid, which can meet the activity requirements of different slags (such as high-calcium carbide slag and low-calcium tailings). At the same time, an appropriate amount of boric acid adsorbs on the surface of the slag to inhibit OH⁻ erosion, delay the gel formation time reaction, and enable the gel to be produced slowly and orderly, thereby improving the strength.

[0020] 2. The slag-based cementitious material and its preparation method provided by the present invention. The alkaline activator contains 20-25% kiln ash and a certain amount of alkaline oxides (K2O + Na2O). By replacing the traditional alkaline activator, the reuse of industrial solid wastes is realized simultaneously, so as to achieve the purposes of cost reduction, environmental protection, energy conservation, and emission reduction.

[0021] 3. The slag-based cementitious material and its preparation method provided by the present invention. The main material is composed of several kinds of industrial waste residues. The main component of industrial by-product gypsum is CaSO4·2H2O. Gypsum dihydrate (CaSO4·2H2O) dissolves in water, releasing Ca²⁺ and SO4 2- , steel slag and carbide slag mainly provide calcium sources, granulated blast furnace slag powder and tailings mainly provide silicon-aluminum sources. Under the action of the alkaline activator, industrial by-product gypsum can further stimulate the activity of the slag to form a double-network structure of "C-S-H gel + ettringite", thereby improving the mechanical properties.

[0022] 4. A slag-based cementitious material provided by the present invention and its preparation method. The preparation method is simple, with few equipment and processes, energy-saving and consumption-reducing, in line with the low-carbon environmental protection policy. It mainly uses industrial slag as the main raw material, has a low cost, and the obtained slag-based cementitious material has a high added value, which can create good social benefits. Specific embodiments

[0023] The technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work fall within the protection scope of the present invention.

[0024] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0025] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", "connection" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0026] The present invention will be further explained and described below in conjunction with specific embodiments.

[0027] A slag-based cementitious material provided by this embodiment includes a main material and an alkaline activator. The main material consists of granulated blast furnace slag powder, industrial by-product gypsum, concrete waste, tailings, and carbide slag; the alkaline activator consists of kiln dust, plant ash, slaked lime, sodium hydroxide, and boric acid. The weight ratio of the main material to the alkaline activator is 100:0.5 - 5; by weight, the alkaline activator consists of 0 - 30 parts of kiln dust, 0 - 20 parts of plant ash, 0 - 50 parts of slaked lime, 30 - 50 parts of sodium hydroxide, and 0.1 - 1 part of boric acid, with a moisture content of 2 - 5% and a specific surface area of ≥400 m² / kg; among them, the composition of the alkaline activator is different, and its ratio with the main material is different. Preferably, the alkaline activator consists of 22 parts of kiln dust, 16 parts of plant ash, 30 parts of slaked lime, 31.5 parts of sodium hydroxide, and 0.5 part of boric acid, with a moisture content of 2.5% and a specific surface area of 400 ± 20 m² / kg. Preferably, the weight ratio of the main material to the alkaline activator is 100:3 - 4. According to the above ratio, weigh kiln dust, plant ash, slaked lime, sodium hydroxide, and boric acid, and ball mill and mix them evenly to prepare the alkaline activator for standby.

[0028] Further, by weight, the main material includes the following raw materials: 45 - 65 parts of granulated blast furnace slag powder, 5 - 20 parts of industrial by-product gypsum, 35 - 55 parts of concrete waste, 0 - 10 parts of tailings, and 0 - 3 parts of carbide slag; preferably, the specific mineral compositions are as follows: the chemical composition of the granulated blast furnace slag powder is: 47.2% CaO, 25.7% SiO2, 11.6% Al2O3, 6.8% MgO, 2.5% SO3, 1.1% K2O + Na2O, 2.8% Fe2O3, loss on ignition 2.3%, moisture content 12%, specific surface area 400 ± 20 m² / kg; the chemical composition of the industrial by-product gypsum is: 31.6% CaO, 3.6% SiO2, 3.1% Al2O3, 1.5% MgO, 51.9% SO3, 2.6% Fe2O3, loss on ignition 5.7%, moisture content 0.5 - 2%, specific surface area 400 ± 20 m² / kg; the chemical composition of the concrete waste is: 41% CaO, 51.5% SiO2, 1.5% Al2O3, 2.2% MgO, 1.8% SO3, 0.2% Fe2O3, loss on ignition 1.8%, moisture content 1 - 3%, specific surface area 400 ± 20 m² / kg; the chemical composition of the tailings is: 5.6% CaO, 55.6% SiO2, 11.5% Al2O3, 3.4% MgO, 2.2% SO3, 3.3% K2O + Na2O, 5.2% Fe2O3, loss on ignition 13.5%, moisture content 6 - 8%, specific surface area 400 ± 20 m² / kg; the chemical composition of the carbide slag is: 64.6% CaO, 2.8% SiO2, 2.7% Al2O3, 1.5% SO3, loss on ignition 24 - 30%, moisture content 12 - 15%, specific surface area 400 ± 20 m² / kg. Example 1:

[0029] In this example, the alkaline activator consists of 22 parts of kiln dust, 16 parts of plant ash, 30 parts of slaked lime, 31.5 parts of sodium hydroxide, and 0.5 part of boric acid, with a moisture content of 2.5% and a specific surface area of 400 ± 20 m² / kg; the main materials consist of 54 parts of granulated blast furnace slag powder, 15 parts of industrial by-product gypsum, 23 parts of concrete waste, 6 parts of tailings, and 2 parts of carbide slag. The main materials and the alkaline activator are made into 1# slag-based cementitious material according to the weight ratio of 100:3 by the following steps.

[0030] Step 1: Weigh kiln dust, plant ash, slaked lime, sodium hydroxide, and boric acid according to the above proportions and mix them in a mixer for 5 minutes to obtain the alkaline activator.

[0031] Step 2: Weigh blast furnace slag powder, industrial by-product gypsum, concrete waste, tailings, carbide slag, and the alkaline activator according to the above proportions, mix them evenly and then enter a vertical mill for grinding for 2 minutes.

[0032] Step 3: Separate through a separator to screen out particles with a specific surface area ≥ 400 m² / kg.

[0033] Step 3: Collect and bag them. If the fineness requirement is not met, return them to the mill for re-grinding; the qualified finished products are carried by gas into a bag filter, and the gas and materials are separated through the bag. Example 2:

[0034] The difference between this Example 2 and Example 1 is that: The alkaline activator consists of 22 parts of kiln dust, 16 parts of plant ash, 30 parts of slaked lime, 31.5 parts of sodium hydroxide, and 0.5 part of boric acid, with a moisture content of 2.5% and a specific surface area of 400 ± 20 m² / kg; the main materials consist of 56 parts of granulated blast furnace slag powder, 20 parts of industrial by-product gypsum, 16 parts of concrete waste, 5 parts of tailings, and 3 parts of carbide slag. The main materials and the alkaline activator are made into slag-based cementitious material according to the weight ratio of 100:4.

[0035] In this example, mix in the mixer for 8 minutes and grind in the vertical mill for 5 minutes. All other production steps are the same as those in Example 1 to obtain 2# slag-based gel material. Example 3:

[0036] The difference between this Example 3 and Example 1 is that: The alkaline activator consists of 30 parts of kiln dust, 19.2 parts of slaked lime, 50 parts of sodium hydroxide, and 0.8 part of boric acid, with a moisture content of 2.5% and a specific surface area of 400 ± 20 m² / kg; the main materials consist of 45 parts of granulated blast furnace slag powder, 5 parts of industrial by-product gypsum, and 50 parts of concrete waste. The main materials and the alkaline activator are made into slag-based cementitious material according to the weight ratio of 100:2.

[0037] In this embodiment, the mixture is mixed in the mixer for 6 minutes and ground in the vertical mill for 6 minutes. All other manufacturing steps are the same as those in Embodiment 1, and the 3# slag-based gel material is prepared. Embodiment 4:

[0038] The difference between this Embodiment 4 and Embodiment 1 lies in: The alkaline activator consists of 50 parts of slaked lime, 50 parts of sodium hydroxide, and 0.8 part of boric acid, with a moisture content of 2.5% and a specific surface area of 400 ± 20 m² / kg; the main material consists of 65 parts of granulated blast furnace slag powder, 14 parts of industrial by-product gypsum, 10 parts of concrete waste, 10 parts of tailings, and 1 part of carbide slag. The main material and the alkaline activator are used to prepare the slag-based cementitious material in a weight ratio of 100:5.

[0039] In this embodiment, the mixture is mixed in the mixer for 9 minutes and ground in the vertical mill for 8 minutes. All other manufacturing steps are the same as those in Embodiment 1, and the 4# slag-based gel material is prepared. Embodiment 5:

[0040] The difference between this Embodiment 5 and Embodiment 1 lies in: The alkaline activator consists of 15 parts of kiln dust, 14 parts of plant ash, 40 parts of slaked lime, 30 parts of sodium hydroxide, and 1 part of boric acid, with a moisture content of 2.5% and a specific surface area of 400 ± 20 m² / kg; the main material consists of 54 parts of granulated blast furnace slag powder, 15 parts of industrial by-product gypsum, 23 parts of concrete waste, 6 parts of tailings, and 2 parts of carbide slag. The main material and the alkaline activator are used to prepare the slag-based cementitious material in a weight ratio of 100:3.

[0041] In this embodiment, the mixture is mixed in the mixer for 5 minutes and ground in the vertical mill for 10 minutes. All other manufacturing steps are the same as those in Embodiment 1, and the 5# slag-based gel material is prepared.

[0042] Comparative Example 1 The main material composition is the same as that in Embodiment 1. Single water glass is added as the alkaline activator, and the ratio of the main material to water glass is 100:3 by weight. The 6# slag-based gel material is prepared according to the steps of Embodiment 1.

[0043] Comparative Example 2 The main material composition is the same as that in Embodiment 4. Single sodium hydroxide is added as the alkaline activator, and the ratio of the main material to water glass is 100:5 by weight. The 7# slag-based gel material is prepared according to the steps of Embodiment 4.

[0044] According to GB / T1346 "Test Methods for Water Requirement of Normal Consistency, Setting Time and Soundness of Cement", the setting times of the 1# - 7# slag-based gel materials prepared in Embodiments 1 - 5 and Comparative Examples 1 - 2 are measured, and the results are shown in Table 1 below.

[0045] Table 1 Setting time results Setting time / min 1# 2# 3# 4# 5# 6# 7# Initial setting 102 89 90 99 92 156 70 Final setting 242 216 210 228 206 389 185 Comparing No. 1# and No. 6#, it can be seen that using single sodium silicate as the alkaline activator results in a longer setting time, indicating a slower reaction. Comparing No. 4# and No. 7#, it can be seen that using single sodium hydroxide as the alkaline activator shortens the setting time, indicating a faster reaction. The setting times of No. 2#, No. 3# and No. 5# are close to that of No. 4#, all of which are faster than using single sodium silicate as the alkaline activator and slower than using single sodium hydroxide as the alkaline activator. This shows that the alkaline activator provided by this invention makes the reaction rate milder, neither too fast nor too slow, and the generated colloid is more orderly and compact, avoiding the adverse effects caused by too fast or too slow reactions.

[0046] According to GB / T 17671 "Test Method for Strength of Cement Mortar (ISO Method)", the 3-day and 28-day compressive strength tests were carried out on the slag-based gel materials No. 1# to No. 7# prepared in Examples 1 to 5 and Comparative Examples 1 to 2. The results are shown in Table 2 below.

[0047] Table 2 Compressive strength results Compressive strength / MPa 1# 2# 3# 4# 5# 6# 7# 3d 28.6 29.4 30.6 29.0 28.7 25.6 28.9 28d 59.8 62.3 66.7 58.4 62.6 53.9 56.7 Comparing No. 1# and No. 6#, No. 4# and No. 7#, it can be seen that using single sodium silicate or sodium hydroxide as the alkaline activator results in relatively small compressive strengths, indicating that too fast or too slow reactions are not conducive to the formation of strength. The compressive strengths of No. 2#, No. 3# and No. 5# are close and are also higher than those of No. 6# and No. 7#. In short, after the alkaline activator provided by this invention acts synergistically with the main material, the strength stability is high. This is mainly because a small amount of boric acid is added to the alkaline activator provided by this invention. During the reaction process, boric acid can adsorb on the surface of the slag to inhibit the erosion of OH⁻, delay the reaction time of gel formation, and make the gel form slowly and orderly, thereby improving the strength of the colloid.

[0048] According to GB / T 749 "Test Method for Resistance of Cement to Sulfate Attack", the strength loss rate and expansion rate of the slag-based gel materials No. 1# to No. 7# prepared in Examples 1 to 5 and Comparative Examples 1 to 2 were evaluated in a sulfate environment. The results are shown in Table 3 below.

[0049] Table 3 Strength loss rate and expansion rate in sulfate environment Sulfate environment 1# 2# 3# 4# 5# 6# 7# Strength loss rate <5% <5% <5% <5% <5% >5% >5% Expansion rate <0.2% <0.2% <0.2% <0.2% <0.2% >0.5% >0.5% In a sulfate environment, the strength loss rate and expansion rate of Comparative Examples 1 to 2 are significantly larger than those of Examples 1 to 5, indicating that after the alkaline activator provided by this invention acts synergistically with the main material, the strength stability is high and the durability is better. The kiln dust contains some trace elements such as Sr and La, which can effectively reduce the expansion coefficient and resist sulfate attack at the same time. Each slag in the main material forms a "C-S-H gel + ettringite" double network structure through synergistic reaction with the alkaline activator, thereby greatly improving the chemical stability of the gel material.

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A slag-based cementitious material, characterized in that, It includes main materials and an alkaline activator. The main materials further include granulated blast furnace slag powder, industrial by-product gypsum, concrete waste, tailings, and carbide slag. The alkaline activator includes any one or more of kiln dust, plant ash, and slaked lime, and the alkaline activator further includes sodium hydroxide and boric acid. The weight ratio of the main materials to the alkaline activator is 100:0.5 - 5.

2. The slag-based cementitious material according to claim 1, wherein The alkaline activator, by weight, is composed of 0 - 30 parts of kiln dust, 0 - 20 parts of plant ash, 0 - 50 parts of slaked lime, 30 - 50 parts of sodium hydroxide, and 0.1 - 1 part of boric acid, with a moisture content of 2 - 5% and a specific surface area ≥ 400 m² / kg.

3. The slag-based cementitious material according to claim 1, characterized in that The main materials, by weight, include: 45 - 65 parts of granulated blast furnace slag powder, 5 - 20 parts of industrial by-product gypsum, 10 - 50 parts of concrete waste, 0 - 10 parts of tailings, 0 - 3 parts of carbide slag, with a moisture content of 2 - 5% and a specific surface area ≥ 400 m² / kg.

4. The slag-based cementitious material according to claim 2, characterized in that, The alkaline activator, by weight percentage, includes kiln dust containing 35 - 45% CaO, 40 - 48% SiO2, 7 - 11% Al2O3, 6 - 10% K2O + Na2O, 0.5 - 10% ZnO, 0 - 1% SrO, and a loss on ignition of 1 - 3%.

5. The slag-based cementitious material according to claim 3, wherein The granulated blast furnace slag powder, by weight percentage, has the following chemical composition: 45 - 48% CaO, 23 - 26% SiO2, 9 - 12% Al2O3, 5 - 7% MgO, 2 - 3% SO3, 0.5 - 1.5% K2O + Na2O, 1 - 2.5% Fe2O3, and a loss on ignition of 1 - 3%.

6. The slag-based cementitious material according to claim 3, characterized in that, The industrial by-product gypsum, by weight percentage, has the following chemical composition: 29 - 31% CaO, 1 - 4% SiO2, 2 - 4% Al2O3, 0.5 - 2% MgO, 50 - 54% SO3, 1.5 - 3% Fe2O3, and a loss on ignition of 4.5 - 6%.

7. The slag-based cementitious material according to claim 3, characterized in that, The concrete waste, by weight percentage, has the following chemical composition: 39 - 41% CaO, 45 - 52% SiO2, 1 - 2% Al2O3, 1 - 2.5% MgO, 1.5 - 3% SO3, 0.1 - 0.4% Fe2O3, and a loss on ignition of 1.0 - 3.5%.

8. The slag-based cementitious material according to claim 3, characterized in that, The tailings, by weight percentage, have the following chemical composition: 4 - 6% CaO, 53 - 56% SiO2, 9 - 12% Al2O3, 1.5 - 3.8% MgO, 2 - 3% SO3, 2 - 4% K2O + Na2O, 4 - 7% Fe2O3, and a loss on ignition of 8 - 14%.

9. The slag-based cementitious material according to claim 3, wherein The carbide slag, by weight percentage, has the following chemical composition: 60 - 65% CaO, 1 - 3% SiO2, 1.5 - 3.5% Al2O3, 0.5 - 2% SO3, and a loss on ignition of 24 - 30%.

10. A preparation method of a slag-based cementitious material, characterized in that, It includes the following steps: Step 1: Weigh kiln dust, plant ash, slaked lime, sodium hydroxide, and boric acid in a determined proportion, and mix them in a mixer for 5 - 10 minutes to obtain the alkaline activator; Step 2: Weigh granulated blast furnace slag powder, industrial by-product gypsum, concrete waste, tailings, carbide slag and alkaline activator according to a certain ratio, mix them evenly and then feed them into a vertical mill for grinding for 2 - 10 minutes; Step 3: Separate with a classifier to screen out particles with a specific surface area ≥ 400 m² / kg; Step 4: Collect and bag them. Those that do not meet the fineness requirements are returned to the mill for grinding again; the qualified finished products are carried by gas into a bag filter, and the gas and materials are separated through the bags.