Auxiliary cementitious material for concrete and preparation method and application thereof

Abstract

The present invention provides an auxiliary cementitious material for concrete, a preparation method, and an application thereof. The auxiliary cementitious material comprises the following components in parts by weight: 25-40 parts of modified converter steel slag, 30-40 parts of high-titanium slag, 15-30 parts of modified waste red brick powder, 10-20 parts of desulfurized gypsum, and 0.05-0.1 parts of a grinding aid. The raw materials for the modified converter steel slag include converter steel slag powder, lithium slag powder, calcium-silicon slag powder, and waste red brick powder in a mass ratio of (5.5-7.5):(2-2.5):(1.8-2.4):1; the raw materials for the modified waste red brick powder include waste red brick powder, mixing station waste water, and Ca(OH)2 in a mass ratio of (8-10):(2.2-3.5):1.5. The auxiliary cementitious material of the present invention has enhanced activity due to the coordination of the various components. When applied to concrete, it can play a synergistic and complementary role, increasing the early strength of concrete, reducing efflorescence, and improving its fluidity.

Description

Technical Field

[0001] The present invention relates to the technical field of industrial solid waste construction resource utilization, and in particular to an auxiliary cementitious material for concrete, a preparation method thereof, and an application thereof. Background Art

[0002] As one of the most widely used engineering materials in the world today, cement has been an indispensable building material since the late 20th century due to its advantages such as easy raw material acquisition, great flexibility in construction, and low price. However, the cement production process consumes a lot of energy and resources, emits a lot of CO2, has a serious environmental load, and has low resource utilization, which are particularly prominent problems. In recent years, the trend of resource utilization of bulk industrial solid waste has become increasingly obvious. The large-scale application of industrial waste residue as an auxiliary cementitious material in cement concrete can not only reduce the amount of cement used, help fill the gap in high-quality admixtures, and reduce the cost of concrete, but also help to reduce the pressure of industrial waste residue on the environment and reduce the atmospheric pollution caused by the production of cement concrete, with good economic and social benefits.

[0003] Currently, widely used industrial solid wastes include granulated blast furnace slag powder, fly ash, slag powder, and silica fume. These solid wastes have formed a complete production chain and are widely used as products in industrial construction due to their excellent performance. With the rapid development of industrialization and urbanization in my country and the further advancement of infrastructure construction, the demand for supplementary cementitious materials has further increased. Slag and fly ash are now often in short supply and have become scarce building materials. Furthermore, the performance requirements for supplementary cementitious materials in construction projects are also increasing, resulting in a gradual decrease in the supply of high-quality supplementary cementitious materials and an increase in the prevalence of low-quality supplementary cementitious materials, which seriously impacts construction projects. Other industrial solid wastes, such as converter slag, high-titanium slag, lithium slag, discarded red bricks, and wastewater from mixing plants, lack performance as supplementary cementitious materials due to their inherent properties. Therefore, the development and utilization of new, high-quality supplementary cementitious materials is a pressing challenge for the cement concrete industry.

[0004] Industrial solid wastes such as converter slag, high-titanium slag, lithium slag, discarded red bricks, and waste slurry from mixing plants all have inherent issues that hinder their widespread use in cement concrete. Converter slag has low activity and poor stability; high-titanium slag has a low glass phase and low activity; lithium slag from the salt-extraction of lepidolite contains sodium salts, which can easily cause efflorescence and corrode rebar; discarded red bricks have low activity, making standard excitation ineffective and requiring high energy consumption; and the addition of waste slurry significantly reduces the fluidity of mortar and concrete, but does not affect strength. In summary, these materials are ineffective as auxiliary cementitious materials. Summary of the Invention

[0005] In order to solve the problems existing in the background technology, the present invention provides an auxiliary cementitious material for concrete, a preparation method and application thereof, and the auxiliary cementitious material is made by modifying and grinding solid waste, and can be used as a green and low-carbon auxiliary cementitious material for cement concrete.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] In a first aspect, the present invention provides an auxiliary cementitious material for concrete, comprising the following components in parts by weight: 25-40 parts of modified converter steel slag, 30-40 parts of high-titanium slag, 15-30 parts of modified waste red brick powder, 10-20 parts of desulfurized gypsum, and 0.05-0.1 parts of a grinding aid;

[0008] The raw materials of the modified converter steel slag include converter steel slag powder, lithium slag powder, calcium silicon slag powder and waste red brick powder in a mass ratio of (5.5-7.5):(2-2.5):(1.8-2.4):1;

[0009] The raw materials of the modified waste red brick powder include waste red brick powder, mixing station waste slurry water and Ca(OH)2 in a mass ratio of (8-10):(2.2-3.5):1.5, and the mass of the mixing station waste slurry water is calculated based on its solid content.

[0010] According to the above scheme, the modified converter steel slag is obtained by calcining a composite powder composed of various raw materials at 1200-1300° C. and then quenching with water and rapidly cooling.

[0011] According to the above scheme, the modified waste red brick powder is obtained by calcining and activating the waste red brick powder at 700-750° C. and then mixing it with waste slurry water from a mixing station and Ca(OH) 2.

[0012] According to the above scheme, the specific surface area of ​​the converter slag powder is 400-500m 2 / kg, the content of SiO2 and Al2O3 in the lithium slag powder is 75% to 80%, and the specific surface area is 400 to 450m 2 / kg, the alkali content of the calcium silicate slag powder is 1% to 1.5%, and the specific surface area is 430 to 450m 2 / kg, the specific surface area of ​​the waste red brick powder is 300-400m 2 / kg.

[0013] According to the above scheme, the high-titanium slag is water-quenched and rapidly cooled high-titanium slag with a TiO2 content of 10% to 15% produced after smelting pig iron from vanadium-titanium magnetite.

[0014] According to the above scheme, the grinding aid is a mixture of triethanolamine methacrylate, waste glycerol, lignin and sugarcane molasses in a mass ratio of (1.5-2.5):(0.8-1.6):(0.6-1.2):1.

[0015] In a second aspect, the present invention provides a method for preparing the auxiliary cementitious material for concrete, comprising the following steps:

[0016] S1. The weighed modified converter slag, high-titanium slag, modified waste red brick powder and desulfurization gypsum were placed in a planetary ball mill, and a weighed grinding aid was added and evenly sprinkled on the solid material;

[0017] S2. Start grinding and grind the above materials in a ball mill to a specific surface area of ​​500m 2 / kg or more of fine powder, that is, the auxiliary cementitious material for concrete is obtained.

[0018] According to the above scheme, the preparation method of the modified converter steel slag is: converter steel slag powder, lithium slag powder, calcium silicon slag powder and waste red brick powder are weighed and mixed evenly according to the mass ratio to obtain a composite powder, the composite powder is pressed into a cake and placed in a muffle furnace for calcination at 1250-1300°C for 20-30 minutes, then taken out, quenched with water for rapid cooling, dried and crushed to obtain the modified converter steel slag.

[0019] According to the above scheme, the preparation method of the modified waste red brick powder is: the waste red brick powder is placed in a muffle furnace and calcined at 700-750°C for 1.5-2h, after being dispersed, the powder is cooled and mixed with the waste slurry water from the mixing station and Ca(OH)2, and then dispersed after drying to obtain the modified waste red brick powder.

[0020] In a third aspect, the present invention provides a use of the auxiliary cementitious material for concrete, which is used to replace part of the cement in preparing concrete, wherein the replacement ratio of cement in the concrete is not higher than 50%.

[0021] According to the above scheme, the replacement ratio of cement in concrete is 30% to 50%.

[0022] The beneficial effects of the present invention are:

[0023] The converter steel slag powder in the present invention is modified by adding lithium slag powder, calcium silicon slag powder and waste red brick powder to high temperature. On the one hand, more active aluminum silicon minerals are introduced, and the mineral composition inside the steel slag is changed at high temperature, and more active minerals such as C3S and C2S are generated, thereby improving the activity of the steel slag powder. On the other hand, the lithium slag powder, calcium silicon slag powder and waste red brick powder contain more silicon aluminum calcium iron oxide minerals. At high temperature, the RO phase in the steel slag is separated into solid and liquid, and f-CaO and f-MgO are dispersed, and thermochemical reaction occurs with the minerals in the composite material, wherein f-CaO reacts with C2S to generate C 3S, f-MgO and Fe2O3 in the mixture system generate MgFe2O4 phase. Most importantly, the lithium slag contains trace amounts of Na, K, Ti and Mg, which can promote the formation of C3S and further greatly reduce the content of f-CaO. The reduction of the two free oxides greatly improves the stability of the steel slag. Finally, the modified steel slag is cooled by water quenching, which can increase the glass content in the steel slag and ensure that the MgFe2O4 phase will not be transformed into f-MgO again due to too slow temperature reduction. While improving the activity of the steel slag, its stability is guaranteed.

[0024] The modified waste red brick powder has gone through three stages: high-temperature calcination, alkali activation and grinding. Under high-temperature calcination, the aluminosilicate mineral structure in the waste red brick powder is destroyed and reorganized, and the overall structure changes from "inert" to "metastable", and the activity is further increased; the waste slurry water from the mixing station is an alkaline solution, which cooperates with Ca(OH)2 to further activate the calcined waste red brick powder, further improving the activation of the red brick powder; the waste slurry water used has a short aging time, which usually contains hydrated calcium aluminate and other unhydrated C2S and C3S and other active minerals, which react with Ca(OH)2, The waste red brick powder begins to hydrate after being mixed together. It is in a partially hydrated state before drying, becoming an "intermediate state" active mineral that is beneficial to promoting the hydration reaction of the cementitious system. The entire component can be hydrated quickly, thereby accelerating the hydration of the entire cementitious system and contributing to the increase in concrete strength. The modified waste red bricks are added to the ball mill together with the other components for joint grinding, and the fineness is reduced and is smaller than that before modification. The smaller the particle size of the waste red brick powder, the more conducive it is to forming a denser microstructure, which is beneficial to the activation of its potential volcanic ash activity and further enhances its activity.

[0025] Both steel slag and high-titanium slag are industrial wastes with poor grindability, and the energy consumption required for grinding is relatively high. The grinding aid is a mixture of triethanolamine methacrylate, waste glycerol, lignin and sugarcane molasses. Among them, triethanolamine methacrylate has a strong grinding effect and can eliminate the inhibitory effect of triethanolamine on cement hydration. The four chemical agents are compounded in a suitable proportion, which can not only improve the grinding effect, but also improve the particle grading and enhance the early strength effect of the agent. At the same time, it can promote the hydration of C3A and C3S, improve the early strength of the mixed material, and improve the density and uniformity of the product structure.

[0026] The auxiliary cementitious materials for concrete of the present invention are all derived from solid wastes and are prepared by modification and co-grinding. The activity of modified converter steel slag and modified red brick powder is improved. Under the alkali excitation of desulfurized gypsum and high-titanium slag, the activity is further improved. After being applied to cement concrete, they play a synergistic and complementary role. The selected several different industrial solid wastes contain aluminate (amorphous C 12 A7), silicate (β-C2S), sulfate, and active SiO2, among other mineral phase characteristics, can achieve an alkali-activated effect. By adjusting the component ratios and adding a performance modifier, the auxiliary cementitious material of the present invention can be adjusted and controlled to meet or match the requirements of different cement concrete materials, greatly improving its adaptability and application range. This can reduce the amount of cement used, overcoming the shortcomings of using industrial waste such as steel slag, high-titanium slag, and discarded red bricks as auxiliary cementitious materials, which result in slow strength development and low early strength due to low activity.

[0027] The addition of lithium slag powder to the auxiliary cementitious material for concrete of the present invention has a promoting effect on strength, can significantly improve the appearance of cement hydration products, form a network structure, and is more compact, thereby improving the problem of low strength of converter steel slag, high-titanium slag, and waste red brick powder systems; the waste red brick powder has a fluffy structure and can absorb sodium ions easily leached from lithium slag when applied to cement concrete, thereby reducing the alkali efflorescence phenomenon of concrete specimens; the high-titanium slag powder can significantly improve the problem of low flowability of concrete mixed with waste slurry water, waste red brick powder, and lithium slag powder; the desulfurized gypsum is used to optimize the amorphous C in steel slag. 12 The generation of hydration products of A7 minerals can also regulate the C 12 The hydration hardening rate of A7 mineral phase prevents C 12 A7 hydrates too quickly and covers the surface of the unhydrated β-C2S mineral, affecting its later hydration.

[0028] The auxiliary cementitious material for concrete of the present invention is prepared from industrial solid waste, so that the industrial solid waste can be efficiently used in concrete materials, promoting the green, low-carbon and sustainable development of cement concrete materials, and having broad application value. DETAILED DESCRIPTION

[0029] The principles and features of the present invention are described below in conjunction with specific embodiments. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0030] The technical solution of the present invention to solve the above technical problems is as follows:

[0031] In the first aspect, the present invention provides an auxiliary cementitious material for concrete, comprising the following components in parts by mass: 25 to 40 parts of modified converter steel slag, 30 to 40 parts of high-titanium slag, 15 to 30 parts of modified waste red brick powder, 10 to 20 parts of desulfurized gypsum and 0.05 to 0.1 parts of grinding aid; the raw materials of the modified converter steel slag include converter steel slag powder, lithium slag powder, calcium silicon slag powder and waste red brick powder in a mass ratio of (5.5 to 7.5): (2 to 2.5): (1.8 to 2.4): 1; the raw materials of the modified waste red brick powder include waste red brick powder, mixing station waste slurry water and Ca(OH)2 in a mass ratio of (8 to 10): (2.2 to 3.5): 1.5, and the mass of the mixing station waste slurry water is calculated based on its solid content.

[0032] Converter slag powder is a high-temperature solid solution waste slag formed by mixing slag-making materials, smelting materials, furnace lining and various metal impurities in the steel production process. It is cooled at room temperature or by water spraying and aged, and then crushed, magnetically separated for iron removal, ground and sieved. In some specific embodiments, the specific surface area of ​​the converter slag powder is 400-500m 2 / kg.

[0033] Lithium slag powder is a solid waste generated during the production of lithium salts from lepidolite ore. In some specific embodiments, the lithium slag powder contains 75% to 80% SiO2 and Al2O3, and has a specific surface area of ​​400 to 450 m2 after grinding. 2 / kg, density 2.5g / cm 3 porous structure powder.

[0034] The calcium silicate slag powder is obtained by dealkalization and grinding of the waste generated after fly ash is sintered with limestone to extract aluminum. Its main mineral components are quartz, calcite, mullite and C2S. In some specific embodiments, the alkali content of the calcium silicate slag powder after dealkalization and grinding is 1% to 1.5%, and the specific surface area is 430 to 450 m 2 / kg.

[0035] Waste red brick powder comes from building red bricks that have become urban solid waste due to modernization construction. It is a fine powder obtained by crushing and grinding waste red bricks with a specific surface area of ​​300-400m 2 / kg.

[0036] High-titanium slag is a water-quenched, rapidly cooled high-titanium slag with a TiO2 content of 10% to 15% produced after smelting pig iron from vanadium-titanium magnetite. Its main components are CaO, SiO2, TiO2, and Al2O3. In some specific embodiments, the particle size is less than 2 cm.

[0037] The waste slurry from the mixing station comes from a concrete mixing station. In some specific embodiments, the waste slurry is aged before use, with an aging time of 4 to 6 hours, a solid content of 10 to 12%, and a pH value of 9 to 11.

[0038] In some specific embodiments, the Ca(OH)2 is an analytically pure chemical reagent with a content of ≥95%.

[0039] Desulfurized gypsum is obtained from the flue gas desulfurization device of the steel plant. The desulfurized gypsum is dried, ground, sieved, and calcined by boiling. In some specific embodiments, the specific surface area of ​​the desulfurized gypsum (CaSO4·2H2O) is 300m 2 / kg~400m 2 / kg, density is 2.3g / cm 3 .

[0040] In some specific embodiments, the modified converter slag is obtained by calcining a composite powder composed of various raw materials at 1200-1300° C. and then quenching with water and rapidly cooling.

[0041] In some specific embodiments, the modified waste red brick powder is obtained by calcining and activating waste red brick powder at 700-750° C. and then mixing it with waste slurry water from a mixing station and Ca(OH) 2 .

[0042] In some specific embodiments, the grinding aid is a mixture of triethanolamine methacrylate, waste glycerol, lignin and sugarcane molasses in a mass ratio of (1.5-2.5):(0.8-1.6):(0.6-1.2):1.

[0043] The present invention provides a method for preparing the auxiliary cementitious material for concrete, comprising the following steps:

[0044] S1. The weighed modified converter slag, high-titanium slag, modified waste red brick powder and desulfurization gypsum were placed in a planetary ball mill, and a weighed grinding aid was added and evenly sprinkled on the solid material;

[0045] S2. Start grinding and grind the above materials in a ball mill to a specific surface area of ​​500m 2 / kg or more of fine powder, that is, the auxiliary cementitious material for concrete is obtained.

[0046] In some specific embodiments, the preparation method of the modified converter steel slag is: converter steel slag powder, lithium slag powder, calcium silicon slag powder and waste red brick powder are weighed and mixed evenly according to a mass ratio to obtain a composite powder, the composite powder is pressed into a cake and placed in a muffle furnace and calcined at 1250-1300°C for 20-30 minutes, then taken out, quenched with water and cooled, dried and crushed to obtain the modified converter steel slag.

[0047] Specifically, the composite powder is mixed with an appropriate amount of water, placed under a mold, and pressed into a cylindrical cake with a diameter of 4 cm and a height of 3 cm under a press of ≤30 MPa. The cake is then evenly placed in a corundum crucible, and the corundum crucible containing the composite cake is placed in a muffle furnace for heating. The temperature is designed to be 1250-1300°C, and the heating rate is set to 10°C / min. After keeping warm for 20-30 minutes, the crucible is taken out, and the high-temperature clinker taken out is cooled by water quenching and extremely cold. After the clinker temperature drops to room temperature, it is taken out and dried, and then the cooled clinker is crushed to a size of less than 2 cm for standby use.

[0048] In some specific embodiments, the holding temperature is 1250°C, the holding time is 30 min, the heating rate is 10°C / min, and the drying temperature is 60±5°C.

[0049] According to the above scheme, the preparation method of the modified waste red brick powder is: the waste red brick powder is placed in a muffle furnace and calcined at 700-750°C for 1.5-2h, after being dispersed, the powder is cooled and mixed with the waste slurry water from the mixing station and Ca(OH)2, and then dispersed after drying to obtain the modified waste red brick powder.

[0050] Specifically, a corundum crucible containing waste red brick powder is placed in a muffle furnace for heating. The temperature is designed to be 700-750°C, and the heating rate is set to 10°C / min. After the temperature is reached, the crucible is taken out and kept warm for 1.5-2 hours, and the waste red brick powder is broken up. After it drops to a constant temperature, it is set aside. After the cooled burned waste red brick powder, the waste slurry water from the mixing station and Ca(OH)2 are evenly mixed, and allowed to stand for 4-6 hours. It is then placed in a 60±5°C oven for drying and broken up for later use.

[0051] In a third aspect, the present invention provides a use of the auxiliary cementitious material for concrete, which is used to replace part of the cement in preparing concrete, wherein the replacement ratio of cement in the concrete is not higher than 50%.

[0052] In some specific embodiments, the replacement ratio of cement in concrete is 30% to 50%.

[0053] The following are specific examples and comparative examples. The cement used is P·O42.5R cement produced by Sichuan Esheng Cement Company, with a 3d compressive strength of 31.5 MPa and a 28d compressive strength of 54.1 MPa.

[0054] Example 1

[0055] First, 30 parts of modified converter steel slag (the ratio of converter steel slag powder, lithium slag powder, calcium silicon slag powder and waste red brick powder is 5.5:2.2:2:1), 35 parts of high titanium slag, 20 parts of modified waste red brick powder (the ratio of waste red brick powder, mixing station waste slurry water and Ca(OH)2 is 8.2:2.5:1.5), and 15 parts of desulfurization gypsum are uniformly mixed according to mass ratio or number; secondly, 18 parts of triethanolamine methacrylate, 10 parts of waste glycerol, 8 parts of lignin and 10 parts of sugarcane molasses are uniformly mixed according to mass ratio or number to prepare a composite grinding aid; then, before entering the planetary ball mill for grinding, 0.06 parts of the grinding aid are uniformly sprayed on the above solid materials according to mass ratio or number; finally, the above materials are ground in the planetary ball mill to 500±15m 2 / kg of fine powder to obtain the green low-carbon auxiliary cementitious material for cement concrete.

[0056] Example 2

[0057] First, 25 parts of modified converter steel slag (converter steel slag powder, lithium slag powder, calcium silicon slag powder and waste red brick powder in a ratio of 6:2.4:1.9:1), 40 parts of high titanium slag, 25 parts of modified waste red brick powder (waste red brick powder, mixing station waste slurry water and Ca(OH)2 in a ratio of 8.5:3.1:1.5), and 10 parts of desulfurization gypsum are uniformly mixed according to mass ratio or number; secondly, 20 parts of triethanolamine methacrylate, 12 parts of waste glycerol, 10 parts of lignin and 10 parts of sugarcane molasses are uniformly mixed according to mass ratio or number to prepare a composite grinding aid; then, before entering the planetary ball mill for grinding, 0.08 parts of the grinding aid is evenly sprayed on the above solid materials according to mass ratio or number; finally, the above materials are ground in the planetary ball mill to 500±15m 2 / kg of fine powder to obtain the green low-carbon auxiliary cementitious material for cement concrete.

[0058] Example 3

[0059] First, 35 parts of modified converter steel slag (the ratio of converter steel slag powder, lithium slag powder, calcium silicon slag powder and waste red brick powder is 6.8:2.5:2.3:1), 35 parts of high titanium slag, 15 parts of modified waste red brick powder (the ratio of waste red brick powder, mixing station waste slurry water and Ca(OH)2 is 9.2:2.8:1.5), and 15 parts of desulfurization gypsum are uniformly mixed according to mass ratio or number; secondly, 18 parts of triethanolamine methacrylate, 14 parts of waste glycerol, 11 parts of lignin and 10 parts of sugarcane molasses are uniformly mixed according to mass ratio or number to prepare a composite grinding aid; then, before entering the planetary ball mill for grinding, 0.06 parts of the grinding aid are uniformly sprayed on the above solid materials according to mass ratio or number; finally, the above materials are ground in the planetary ball mill to 500±15m 2 / kg of fine powder to obtain the green low-carbon auxiliary cementitious material for cement concrete.

[0060] Comparative Example 1

[0061] Taking Example 3 as an example, the ratio of converter steel slag powder, lithium slag powder, calcium silicon slag powder and waste red brick powder in the modified converter steel slag is 8.5:3:2.5:1, and the other components and preparation process remain unchanged.

[0062] Comparative Example 2

[0063] Taking Example 3 as an example, the ratio of waste red brick powder, mixing station waste slurry water and Ca(OH)2 in the modified waste red brick powder is 11.5:4.1:1.5, and the other components and preparation process remain unchanged.

[0064] Comparative Example 3

[0065] Taking Example 3 as an example, the modified converter slag is heated in a muffle furnace at a temperature designed to be 1450-1500° C., and other components and preparation processes remain unchanged.

[0066] Comparative Example 4

[0067] Taking Example 3 as an example, the modified waste red brick powder is heated in a muffle furnace at a temperature designed to be 550-600° C., while other components and preparation processes remain unchanged.

[0068] Comparative Example 5

[0069] The industrial waste converter slag (specific surface area of ​​505m2) produced by the steelmaking process of a steel plant in Sichuan was selected. 2 / kg) as comparative example 5.

[0070] Comparative Example 6

[0071] The high-titanium slag (specific surface area of ​​488m2) produced by the steelmaking process of a steel plant in Sichuan was selected as the industrial waste. 2 / kg) as comparative example 6.

[0072] Comparative Example 7

[0073] Waste red bricks removed from a construction site in Sichuan were selected and ground and sieved to obtain waste red brick powder (specific surface area of ​​520m 2 / kg) as comparative example 7.

[0074] Application Examples

[0075] Cement concrete was prepared by replacing 50% of the P·O42.5 cement with the auxiliary cementitious materials for concrete prepared in Examples 1-3 and Comparative Examples 1-4, and the converter steel slag, high-titanium slag, and waste red brick powder of Comparative Examples 5-7, respectively. The mortar activity index, mortar fluidity, and volume stability tests were performed according to the methods in the standards GB / T1596-2017 "Fly ash used in cement and concrete", GB / T2419-2005 "Determination of fluidity of cement mortar", and GB / T 1346-2011 "Test method for water content, setting time, and stability of cement at standard consistency". The volume stability test method used the Leclerc clamp method. The results are shown in Table 1.

[0076] Table 1 Comparison of experimental parameters between the embodiment and the control group

[0077]

[0078] From the comparison of the data of the comparative examples in Table 1, it can be seen that: the converter steel slag powder has little effect on the fluidity of the mortar, but the expansion value increases significantly and the volume stability is unqualified; the high-titanium slag promotes the fluidity of the mortar, and the discarded red brick powder greatly reduces the fluidity of the mortar, and after the three are replaced by cement, the mortar activity index decreases significantly, that is, the mortar strength decreases significantly, indicating that the addition of the three solid wastes has a reducing effect on the strength of the system; comparing the results of Example 3 and Comparative Examples 1-4 in the table, when the composition of the modified steel slag and the modified red brick powder is changed, the expansion value of the mortar increases and the activity index decreases relatively; after increasing the high-temperature reconstruction temperature of the modified steel slag, the expansion value of the mortar increases significantly; after lowering the reconstruction temperature of the modified red brick powder, the activity index of the mortar decreases. The number is reduced, and changing the range conditions of different components will affect the composition of the auxiliary cementitious material, and the stability and activity of the auxiliary cementitious material will change accordingly; when the composite admixture obtained by grinding modified steel slag, modified red brick and high titanium slag together is used, compared with the comparative example 5 in which only converter steel slag is added, the expansion value of the mortar is reduced, and its stability is significantly improved. Compared with the comparative example 7 in which only waste red bricks are added, the fluidity of the mortar is improved. Compared with comparative examples 5-7, the mortar activity index is significantly increased, the mortar strength is significantly improved, and the 3d activity index is above 75%. In particular, the activity index of Example 3 is the highest, and it shows high activity as an auxiliary cementitious material, indicating that it can be used as a green and low-carbon auxiliary cementitious material for cement concrete.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An auxiliary cementitious material for concrete, characterized in that: The invention comprises the following components in parts by weight: 25 to 40 parts of modified converter steel slag, 30 to 40 parts of high-titanium slag, 15 to 30 parts of modified waste red brick powder, 10 to 20 parts of desulfurized gypsum and 0.05 to 0.1 parts of grinding aid; The raw materials of the modified converter steel slag include converter steel slag powder, lithium slag powder, calcium silicon slag powder and waste red brick powder in a mass ratio of (5.5-7.5):(2-2.5):(1.8-2.4):1; The raw materials of the modified waste red brick powder include waste red brick powder, mixing station waste slurry water and Ca(OH)2 in a mass ratio of (8-10):(2.2-3.5):1.5, and the mass of the mixing station waste slurry water is calculated based on its solid content.

2. The auxiliary cementitious material for concrete according to claim 1, characterized in that: The modified converter steel slag is obtained by calcining a composite powder composed of various raw materials at 1200-1300° C. and then quenching and rapidly cooling the composite powder.

3. The auxiliary cementitious material for concrete according to claim 1, characterized in that: The modified waste red brick powder is obtained by calcining and activating waste red brick powder at 700-750° C. and then mixing it with waste slurry water from a mixing station and Ca(OH)2.

4. The auxiliary cementitious material for concrete according to claim 1, characterized in that: The specific surface area of ​​the converter slag powder is 400 to 500 m 2 / kg, the content of SiO2 and Al2O3 in the lithium slag powder is 75% to 80%, and the specific surface area is 400 to 450m 2 / kg, the alkali content of the calcium silicate slag powder is 1% to 1.5%, and the specific surface area is 430 to 450m 2 / kg, the specific surface area of ​​the waste red brick powder is 300-400m 2 / kg.

5. The auxiliary cementitious material for concrete according to claim 1, characterized in that: The high-titanium slag is water-quenched and rapidly cooled high-titanium slag with a TiO2 content of 10% to 15% and produced after smelting pig iron from vanadium-titanium magnetite.

6. The auxiliary cementitious material for concrete according to claim 1, characterized in that: The grinding aid is a mixture of triethanolamine methacrylate, waste glycerin, lignin and sugarcane molasses in a mass ratio of (1.5-2.5):(0.8-1.6):(0.6-1.2):

1.

7. The method for preparing the auxiliary cementitious material for concrete according to any one of claims 1 to 6, characterized in that: The steps include: S1. The weighed modified converter slag, high-titanium slag, modified waste red brick powder and desulfurization gypsum were placed in a planetary ball mill, and a weighed grinding aid was added and evenly sprinkled on the solid material; S2. Grind the above materials in a ball mill to a specific surface area of ​​500m 2 / kg or more of fine powder, that is, the auxiliary cementitious material for concrete is obtained.

8. The method for preparing the auxiliary cementitious material for concrete according to claim 7, characterized in that: The modified converter steel slag is prepared by weighing converter steel slag powder, lithium slag powder, calcium silicon slag powder and waste red brick powder according to a mass ratio and uniformly mixing them to obtain a composite powder; pressing the composite powder into a cake and then placing it in a muffle furnace for calcining at 1250-1300° C. for 20-30 minutes; then taking it out, quenching it with water, rapidly cooling it, drying it and then crushing it to obtain the modified converter steel slag.

9. The method for preparing the auxiliary cementitious material for concrete according to claim 7, characterized in that: The preparation method of the modified waste red brick powder is as follows: the waste red brick powder is placed in a muffle furnace and calcined at 700-750° C. for 1.5-2 hours, the powder is dispersed, the powder is cooled, and the powder is mixed with waste slurry water from a mixing station and Ca(OH)2, and the powder is dispersed after drying to obtain the modified waste red brick powder.

10. The use of the auxiliary cementitious material for concrete according to any one of claims 1 to 6, characterized in that: Used to replace part of cement in the preparation of concrete, and the replacement ratio of cement in concrete shall not exceed 50%.

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