Green low-carbon cementitious material and preparation method thereof

Abstract

The application provides a kind of green low carbon cementitious material and its preparation method, belong to building material technical field.The application first carries out pretreatment to converter slag to obtain superfine converter slag, so as to improve the activity and fluidity of converter slag;By compounding sodium hydroxide, liquid water glass and sodium chloride as alkali activator as alkali activator, so as to improve the early and late compressive strength of concrete obtained by replacing cement with green low carbon cementitious material;The application can further improve the green low carbon cementitious material by adding emulsified asphalt and PE fiber in the raw material, so as to realize the increase of the amount of green low carbon cementitious material that can replace cement.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, and particularly relates to a green low-carbon cementitious material and a preparation method thereof. BACKGROUND

[0002] Converter slag, i.e., converter steel slag, is a waste slag generated in the converter steelmaking process, mainly derived from oxides formed after oxidation of elements contained in molten iron and scrap steel, impurities brought by metal charges, added slagging agents (such as limestone, fluorite, silica), oxidizing agents, desulfurization products and eroded furnace lining materials, and belongs to an industrial waste.

[0003] Traditional cement production generates a large amount of carbon dioxide and has high energy consumption. In the prior art, converter steelmaking and other industrial wastes are usually compounded, and a cementitious material is obtained by using an activator to replace cement in the preparation of concrete admixture. Since converter steelmaking has the characteristics of low cost and high activity, it is used to replace high-energy-consumption and high-pollution cement, which conforms to the green development concept.

[0004] However, when the converter slag-based cementitious material obtained by the preparation method provided in the prior art is used to replace cement, the replacement amount is limited. Therefore, there is an urgent need to provide a preparation method of a green low-carbon cementitious material which can replace cement in a large proportion. SUMMARY

[0005] The present application provides a green low-carbon cementitious material and a preparation method thereof. The green low-carbon cementitious material obtained by the preparation method provided in the present application can replace up to 70wt% of the required amount of cement in concrete.

[0006] In order to achieve the above-mentioned application purposes, the present application provides the following technical solutions:

[0007] The present application provides a preparation method of a green low-carbon cementitious material, comprising the following steps:

[0008] (1) grinding and removing iron from the converter slag to obtain superfine converter slag;

[0009] (2) mixing emulsified asphalt, sodium hydroxide, liquid water glass, sodium chloride and a surfactant to obtain a mixture;

[0010] (3) adding the mixture obtained in step (2) to the superfine converter slag obtained in step (1), and then adding PE fibers to obtain a green low-carbon cementitious material;

[0011] The preparation of steps (1) and (2) is not in a specific order.

[0012] Preferably, the raw material in the green low-carbon cementitious material has a weight composition of 50-90 parts of superfine converter slag, 5-10 parts of emulsified asphalt, 2-5 parts of sodium hydroxide, 5-8 parts of liquid water glass, 1-3 parts of sodium chloride, 1-5 parts of PE fiber, and 0.1-0.5 parts of surfactant sodium.

[0013] Preferably, the Fe2O3 content in the superfine converter slag is ≤1 wt%.

[0014] Preferably, the superfine converter slag has a specific surface area >400 m 2 / kg, an average particle size <20 μm, a D50 <20 μm, and a D90 <35 μm.

[0015] Preferably, the modulus of the liquid water glass is 1.5-1.8.

[0016] Preferably, the emulsified asphalt is an industrial emulsified asphalt with a solid content of 55-65%.

[0017] Preferably, the surfactant includes sodium dodecyl sulfate and / or sodium stearate.

[0018] Preferably, the surfactant is sodium dodecyl sulfate.

[0019] Preferably, the PE fiber has a specification of a length of 10-30 mm, a diameter of 15-35 μm, an aspect ratio of 650-750, and a strength of 2500-3500 MPa.

[0020] The present application provides a preparation method of a green low-carbon cementitious material, including the following steps: grinding and removing iron from converter slag to obtain superfine converter slag; then mixing emulsified asphalt, sodium hydroxide, liquid water glass, sodium chloride, and surfactant to obtain a mixture; and finally adding the mixture to the superfine converter slag and then adding PE fiber to obtain the green low-carbon cementitious material. The present application first pretreats the converter slag to obtain superfine converter slag, thereby improving the activity and fluidity of the converter slag; the present application compounding sodium hydroxide, liquid water glass, and sodium chloride as an alkali activator as an alkali activator, thereby improving the early and late compressive strength of concrete obtained by replacing cement with the green low-carbon cementitious material; the present application further improves the green low-carbon cementitious material by adding emulsified asphalt and PE fiber in the raw material, thereby achieving an increase in the amount of cement that can be replaced by the green low-carbon cementitious material; and the present application adds PE fiber to the green low-carbon cementitious material system at the end, which is conducive to the uniform dispersion of the PE fiber in the green low-carbon cementitious material system. The implementation results show that the green low-carbon cementitious material obtained by using the technical solution provided by the present application can replace up to 70 wt% of the required cement in concrete. DETAILED DESCRIPTION

[0021] The application provides a preparation method of green low-carbon cementitious material.

[0022] (1) grinding and removing iron from the converter slag to obtain superfine converter slag;

[0023] (2) mixing emulsified asphalt, sodium hydroxide, liquid water glass, sodium chloride and a surfactant to obtain a mixture;

[0024] (3) adding the mixture obtained in the step (2) into the superfine converter slag obtained in the step (1), and then adding PE fibers to obtain the green low-carbon cementitious material;

[0025] The preparation of the step (1) and the step (2) is not in a specific order.

[0026] Unless otherwise specified, the source of each component is not specifically limited in the application, and commercially available products known to those skilled in the art can be used.

[0027] The application grinds and removes iron from the converter slag to obtain superfine converter slag.

[0028] In the application, the main chemical composition of the converter slag is preferably 10.0-18.0% of SiO2, 1.0-5.0% of Al2O3, 2.5-12% of Fe2O3, 45.0-55.0% of CaO, 5.0-1.0% of MgO, 0.85-3.85% of TiO2 and the balance of impurities in terms of mass percentage. The application does not have a specific provision for the grinding and iron removal mode, and the converter slag is subjected to iron removal and grinding operation by using the grinding and iron removal mode known to those skilled in the art, so that the particle refinement of the converter slag is realized. In the application, the iron removal is beneficial to the smooth progress of the grinding operation. In the application, the Fe2O3 content in the superfine converter slag is preferably ≤1wt%. In the application, the specific surface area of the superfine converter slag is preferably 400-500 m 2 / kg, the average particle size is preferably <20 μm, D50 is <20 μm, and D90 is <35 μm. Since the hardness of the converter slag is relatively high, further refinement of the converter slag has a large requirement for equipment and a large degree of wear, therefore, from the comprehensive economic point of view, the converter slag is ground to the above specifications in the actual operation process. In the application, the superfine converter slag has high activity and fluidity, and can fill the fine pores of the concrete to improve the compactness of the concrete.

[0029] The application mixes emulsified asphalt, sodium hydroxide, liquid water glass, sodium chloride and a surfactant to obtain a mixture.

[0030] The sodium hydroxide, liquid water glass and sodium chloride are compounded as alkali activator, so that the early and late compressive strength of the green low-carbon cementitious material is improved.In the application, the emulsified asphalt is preferably industrial emulsified asphalt with a solid content of 55-65%.The emulsified asphalt is added to the raw materials, and the adhesion and durability of the emulsified asphalt are utilized, so that the compressive strength of the green low-carbon cementitious material is further improved.In the application, the modulus of the liquid water glass is preferably 1.5-1.8.The liquid water glass with the above modulus is selected as the alkali activator, so that the activation effect on the superfine converter slag is better, and the concrete has better early and late strength when applied to the concrete.In the application, the surfactant preferably includes sodium dodecyl sulfate and / or sodium stearate, and more preferably is sodium dodecyl sulfate.The surfactant is added to the raw materials, so that the strength of the concrete is increased.

[0031] After the superfine converter slag and the mixture are obtained, the mixture is added to the superfine converter slag, and then the PE fiber is added, so that the green low-carbon cementitious material is obtained.

[0032] In the application, the specification of the PE fiber is preferably as follows: the length is 10-30 mm, the diameter is 15-35 μm, the aspect ratio is 650-750, and the strength is 2500-3500 MPa.The PE fiber with the above specification is selected in combination with the use of the emulsified asphalt, so that the compressive strength of the green low-carbon cementitious material is greatly improved.The PE fiber is finally added to the green low-carbon cementitious material system, so that the PE fiber is uniformly dispersed in the green low-carbon cementitious material system.

[0033] In the application, the weight composition of the raw materials in the green low-carbon cementitious material is preferably as follows: the superfine converter slag is 50-90 parts, the emulsified asphalt is 5-10 parts, the sodium hydroxide is 2-5 parts, the liquid water glass is 5-8 parts, the sodium chloride is 1-3 parts, the PE fiber is 1-5 parts, and the surfactant is 0.1-0.5 parts;more preferably, the superfine converter slag is 80 parts, the emulsified asphalt is 7 parts, the sodium hydroxide is 4 parts, the liquid water glass is 6 parts, the sodium chloride is 2 parts, the PE fiber is 3 parts, and the surfactant is 0.3 parts.The amount of the raw materials in the green low-carbon cementitious material is controlled in the above range, so that the green low-carbon cementitious material has the best compressive strength.

[0034] The application also provides the green low-carbon cementitious material prepared by the preparation method.

[0035] The technical solutions in the present application will be clearly and completely described below with reference to the embodiments in the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all the other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the protection scope of the present application.

[0036] In each embodiment, the superfine converter slag has a specific surface area of 400-500 m 2 / kg, an average particle size of <20 μm, a D50 of <20 μm, a D90 of <35 μm; the modulus of the liquid water glass is 1.6; the emulsified asphalt is an industrial emulsified asphalt with a solid content of 61%; the PE fiber has a specification of a length of 15-18 mm, a diameter of 20-22 μm, an aspect ratio of 720-750, and a strength of 3000-3100 MP.

[0037] Embodiment 1

[0038] The preparation method of the green low-carbon cementitious material in the present embodiment is as follows:

[0039] (1) grinding and removing iron from the converter slag to obtain superfine converter slag;

[0040] (2) mixing the emulsified asphalt, sodium hydroxide, liquid water glass, sodium chloride and surfactant to obtain a mixture;

[0041] (3) adding the mixture obtained in step (2) into the superfine converter slag obtained in step (1), and then adding PE fiber to obtain the green low-carbon cementitious material;

[0042] The green low-carbon cementitious material has a weight composition of 80 parts of superfine converter slag, 7 parts of emulsified asphalt, 4 parts of sodium hydroxide, 6 parts of liquid water glass, 2 parts of sodium chloride, 3 parts of PE fiber and 0.3 parts of sodium dodecyl sulfate.

[0043] Embodiment 2

[0044] The difference from Embodiment 1 is that the green low-carbon cementitious material has a weight composition of 50 parts of superfine converter slag, 5 parts of emulsified asphalt, 2 parts of sodium hydroxide, 5 parts of liquid water glass, 1 part of sodium chloride, 1 part of PE fiber and 0.1 part of sodium dodecyl sulfate.

[0045] Embodiment 3

[0046] The difference from Embodiment 1 is that the green low-carbon cementitious material has a weight composition of 90 parts of superfine converter slag, 10 parts of emulsified asphalt, 5 parts of sodium hydroxide, 8 parts of liquid water glass, 3 parts of sodium chloride, 5 parts of PE fiber and 0.5 parts of sodium dodecyl sulfate.

[0047] Comparative Example 1

[0048] The difference from Example 1 is that the emulsified asphalt is replaced by the same amount of superfine converter slag, and the rest is the same as Example 1.

[0049] Comparative Example 2

[0050] The difference from Example 1 is that the PE fiber is replaced by the same amount of superfine converter slag, and the rest is the same as Example 1.

[0051] Concrete is prepared by using the green low-carbon cementitious material prepared in Examples 1-3 and Comparative Examples 1-2 respectively, and performance test is carried out

[0052] In the experiment, the control group: the concrete is composed of the following components by weight: P.O42.5 cement 300 parts, fly ash 80 parts, 5-16 mm continuous graded gravel 1000 parts, river sand with an average particle size of 0.3-0.5 mm 600 parts, water 166 parts and polycarboxylate-based high-efficiency water reducer 4.5 parts.

[0053] Application Example 1

[0054] The concrete is composed of the following components by weight: P.O42.5 cement 90 parts, green low-carbon cementitious material prepared in Example 1 210 parts, fly ash 80 parts, 5-16 mm continuous graded gravel 1000 parts, river sand with an average particle size of 0.3-0.5 mm 600 parts, water 166 parts and polycarboxylate-based high-efficiency water reducer 4.5 parts. The green low-carbon cementitious material replaces 70wt% of the cement in the concrete.

[0055] Application Example 2

[0056] The difference from Application Example 1 is that the following raw materials are changed: P.O42.5 cement 270 parts, green low-carbon cementitious material prepared in Example 1 30 parts, and the rest is the same as Application Example 1. The green low-carbon cementitious material replaces 10wt% of the cement in the concrete.

[0057] Application Example 3

[0058] The difference from Application Example 1 is that the following raw materials are changed: P.O42.5 cement 150 parts, green low-carbon cementitious material prepared in Example 1 150 parts, and the rest is the same as Application Example 1. The green low-carbon cementitious material replaces 50wt% of the cement in the concrete.

[0059] Application Example 4

[0060] The difference from Application Example 1 is that the following raw materials are changed: P.O42.5 cement 75 parts, green low-carbon cementitious material prepared in Example 1 225 parts, and the rest is the same as Application Example 1. The green low-carbon cementitious material replaces 75wt% of the cement in the concrete.

[0061] Application Example 5

[0062] The difference between Application Example 1 and the present application example is that the following raw materials are changed: P.O 42.5 cement 60 parts, green low-carbon cementitious material prepared in Example 1 240 parts, and the rest are the same as in Application Example 1. The green low-carbon cementitious material replaces 80wt% of the cement in the concrete.

[0063] Application Examples 6-9

[0064] The difference between Application Example 1 and Application Examples 6-9 is that the green low-carbon cementitious material is replaced by the green low-carbon cementitious material prepared in Examples 2-3 and Comparative Examples 1-2, respectively.

[0065] The compressive strength of the concrete provided in Application Examples 1-9 at 3d, 7d and 28d was tested according to the Standard Test Methods for Mechanical Properties of Ordinary Concrete (GB / T50081-2011), and the test results are shown in Table 1.

[0066] Table 1: Compressive strength test results of the concrete provided in Application Examples 1-9

[0067]

[0068]

[0069] As can be seen from Table 1, by simultaneously adding emulsified asphalt and PE fibers to the raw materials, the amount of cementitious material that can replace cement is greatly increased using the technical solution provided by the present application. Under the same conditions, the amount of concrete that can be replaced can reach 70wt%.

[0070] In summary, since the technical solution provided by the present application can achieve high cement replacement, the amount of cement used is greatly reduced. This will greatly reduce the environmental pollution caused by cement, so the cementitious material provided by the present application has the advantages of being green and low-carbon.

[0071] The above description is only the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the principles of the present application, several improvements and refinements can be made, and these improvements and refinements should also be considered within the scope of protection of the present application.

Claims

1.A method for preparing a green low-carbon cementitious material, comprising the following steps: (1) grinding and removing iron from converter slag to obtain superfine converter slag; (2) mixing emulsified asphalt, sodium hydroxide, liquid water glass, sodium chloride and a surfactant to obtain a mixture; (3) adding the mixture obtained in step (2) to the superfine converter slag obtained in step (1) and then adding PE fibers to obtain the green low-carbon cementitious material; the preparation of steps (1) and (2) is not in a specific order; the green low-carbon cementitious material comprises, by weight, 50-90 parts of the superfine converter slag, 5-10 parts of the emulsified asphalt, 2-5 parts of the sodium hydroxide, 5-8 parts of the liquid water glass, 2-3 parts of the sodium chloride, 1-5 parts of the PE fibers and 0.1-0.5 parts of the surfactant; the surfactant is sodium dodecyl sulfate; the content of Fe2O3 in the superfine converter slag in step (1) is ≤1 wt%; the modulus of the liquid water glass in step (2) is 1.5-1.8; the emulsified asphalt in step (2) is an industrial emulsified asphalt with a solid content of 55-65%; the PE fibers in step (3) have a length of 10-30 mm, a diameter of 15-35 μm, an aspect ratio of 650-750 and a strength of 2500-3500 MPa. 6.The green low-carbon cementitious material prepared by the method of any one of claims 1-5. ​ ​ ​ ​ The specific surface area of the superfine converter slag in step (1) is > 400 m 2 / kg, average particle size < 20 μm, D50 < 20 μm, D90 < 35 μm; ​ 2. The production method according to claim 1, characterized by, ​ 3. The preparation method according to claim 1, characterized in that, ​ 4. The method of claim 1, wherein, ​ 5. The preparation method according to claim 1, characterized in that, ​ ​

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