Alkali-activated bentonite slurry steel slag foam concrete and preparation method thereof

Abstract

The invention relates to the technical field of building materials, in particular to alkali-activated bentonite slurry and steel slag foam concrete and a preparation method thereof. The alkali-activated bentonite slurry steel slag foam concrete is prepared from the following raw materials in parts by mass: 400 to 440 parts of cement, 25 to 60 parts of expansive soil slurry, 55 to 60 parts of mineral powder, 25 to 30 parts of steel slag powder, 0.8 to 1 part of alkali, 25 to 30 parts of manganese tailings, 260 to 265 parts of water and 30 to 32 parts of foam. The manganese tailings, the steel slag powder and the mineral powder belong to bulk industrial solid wastes, and the bulk industrial solid wastes of the prepared foam concrete account for 25-30%, so that the cement consumption is saved, and the cost is further saved.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, in particular to an alkali-activated bentonite slurry steel slag foam concrete and a preparation method thereof. Background Art

[0002] Steel slag and manganese tailings are common solid wastes. In recent years, with the rapid development of economic construction, the output of products such as steel and manganese metal has become higher and higher, and the amount of waste slag generated has also increased. If the steel slag with potential utilization value is not reasonably and effectively utilized, it will inevitably lead to a large amount of steel slag accumulation, resulting in a waste of land resources and polluting the environment. At present, the overall utilization rate of solid waste is not high, among which the utilization rate of steel slag is less than 30%, and in the field of road materials is less than 10%, it is mainly used in road backfill, pavement base and asphalt concrete surface layer. Therefore, the comprehensive utilization research of solid wastes such as steel slag and manganese tailings is imminent. Summary of the invention

[0003] The purpose of the present invention is to provide an alkali-activated bentonite slurry steel slag foam concrete and a preparation method thereof. The foam concrete has the characteristics of low cost, low cement content, good thermal insulation performance, etc., which not only realizes the utilization of solid waste, but also improves the compressive strength and thermal insulation performance of the foam concrete.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] One of the technical solutions of the present invention is an alkali-activated bentonite slurry steel slag foam concrete, which comprises, by weight, 400-440 parts of cement, 25-60 parts of expanded soil slurry, 55-60 parts of mineral powder, 25-30 parts of steel slag powder, 0.8-1 parts of alkali, 25-30 parts of manganese tailings, 260-265 parts of water and 30-32 parts of foam.

[0006] The second technical solution of the present invention is a method for preparing the above-mentioned alkali-activated bentonite slurry steel slag foam concrete, comprising the following steps:

[0007] Step 1, mixing alkali and water according to mass fractions to obtain an alkali solution, adding mineral powder, steel slag powder, and manganese tailings to the alkali solution and mixing to obtain an alkali-activated solid waste slurry;

[0008] Step 2: Mix cement, alkali-activated solid waste slurry and bentonite slurry and stir them for the first time to obtain a cementitious material mixed slurry, add foam to the cementitious material mixed slurry and stir them for the second time to obtain the alkali-activated bentonite slurry steel slag foam concrete.

[0009] The third technical solution of the present invention is the application of the above-mentioned alkali-activated bentonite slurry steel slag foam concrete in the field of construction engineering.

[0010] The present invention discloses the following technical effects:

[0011] 1. The present invention uses fine manganese tailings as aggregate to prepare foamed concrete, mixes bentonite with water to make bentonite slurry, and uses the bentonite slurry to prepare manganese tailings foamed concrete, so that the internal structure of the foamed concrete produces more tiny bubbles, thereby optimizing the internal structure of the foamed concrete, improving the strength of the foamed concrete, and having lower thermal conductivity, thereby expanding the application range of the foamed concrete.

[0012] 2. The manganese tailings, steel slag powder and mineral powder in the present invention are large-scale industrial solid wastes, and the bulk industrial solid wastes in the prepared foamed concrete account for 25-30%, which saves cement usage and further saves costs.

[0013] 3. The alkali (NaOH) in the present invention can promote the hydration reaction of steel slag powder and mineral powder and improve the strength of foamed concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 The present invention is a flow chart for preparing alkali-activated bentonite slurry steel slag foam concrete.

[0016] Figure 2 This is the SEM image of the alkali-activated bentonite slurry steel slag foam concrete prepared in Example 1.

[0017] Figure 3 This is the SEM image of the alkali-activated bentonite slurry steel slag foam concrete prepared in Example 2.

[0018] Figure 4 This is the SEM image of the alkali-activated bentonite slurry steel slag foam concrete prepared in Example 3.

[0019] Figure 5 This is the SEM image of the foamed concrete prepared in Comparative Example 1.

[0020] Figure 6 This is the SEM image of the foamed concrete prepared in Comparative Example 2.

[0021] Figure 7 This is the SEM image of the foamed concrete prepared in Comparative Example 3. DETAILED DESCRIPTION

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0023] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0024] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0025] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0026] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0027] The "%" described in the present invention, unless otherwise specified, refers to mass percentage.

[0028] Existing studies have shown that solid waste fine aggregate has poor fluidity in cement paste and is easy to aggregate, resulting in paste stratification and inconsistent structure. The prepared foam concrete containing solid waste fine aggregate also has the phenomenon of fine aggregate sedimentation and aggregation becoming more obvious as the density decreases, resulting in its mechanical properties being adversely affected. Therefore, in order to improve the fluidity of cement slurry in foam concrete and further improve the strength and durability of foam concrete materials, the present invention makes full use of the good water absorption and expansion of bentonite, and proposes an alkali-activated bentonite slurry steel slag foam concrete and a preparation method thereof on the basis of conducting a large number of experiments, which improves the pore structure of foam concrete, improves the strength and thermal insulation performance, saves cement consumption, further improves the comprehensive utilization rate of solid wastes such as steel slag and manganese tailings, and reduces environmental pollution.

[0029] The first aspect of the present invention provides an alkali-activated bentonite slurry steel slag foam concrete, which comprises, by weight, 400-440 parts of cement, 25-60 parts of expanded soil slurry, 55-60 parts of mineral powder, 25-30 parts of steel slag powder, 0.8-1 parts of alkali, 25-30 parts of manganese tailings, 260-265 parts of water and 30-32 parts of foam.

[0030] In a preferred embodiment of the present invention, the cement is PO 42.5; and the alkali is NaOH.

[0031] In a preferred embodiment of the present invention, the expanded soil slurry is prepared by mixing bentonite with water; the volume ratio of the bentonite to the water is 1:15.

[0032] In a preferred embodiment of the present invention, after the bentonite and water are mixed and stirred, the step of standing for 24 hours is also included. The purpose of standing for 24 hours is: (1) to ensure that all bentonite particles fully absorb water and swell to form a mud with good fluidity and stability; (2) standing for 24 hours helps to make the particles in the mud more evenly distributed and reduce sedimentation and stratification; (3) standing for 24 hours allows these bubbles to have enough time to float up and escape, thereby avoiding the existence of bubbles during the construction process affecting the quality of the project.

[0033] In the present invention, the foam is prepared by mixing and stirring a foaming agent and water at a mass ratio of 1:30, and foaming. The rotation speed during stirring should be not less than 700 rpm, generally between 700 and 1400 rpm, the circumferential speed of the impeller end should be >20 m / s, and the bubble conversion rate of the foaming agent should be not less than 70%.

[0034] In a preferred embodiment of the present invention, the mineral powder is S105 grade mineral powder; the steel slag powder is 200-300 mesh converter slag steel slag powder; and the particle size of the manganese tailings is 0-1mm, and is not 0.

[0035] In a preferred embodiment of the present invention, the amount of alkali added is 1% of the sum of the mass of the mineral powder and the steel slag powder.

[0036] In the present invention, when preparing the alkali-activated bentonite slurry steel slag foam concrete, the water-to-material ratio is 0.45, wherein the water-to-material ratio is the ratio of the sum of the mass of water to cement, manganese tailings, steel slag powder, mineral powder and bentonite slurry.

[0037] The second aspect of the present invention provides a method for preparing the above-mentioned alkali-activated bentonite slurry steel slag foam concrete, comprising the following steps:

[0038] Step 1, mixing alkali and water according to mass fractions to obtain an alkali solution, adding mineral powder, steel slag powder, and manganese tailings to the alkali solution and mixing to obtain an alkali-activated solid waste slurry;

[0039] Step 2: Mix cement, alkali-activated solid waste slurry and bentonite slurry and stir them for the first time to obtain a cementitious material mixed slurry, add foam to the cementitious material mixed slurry and stir them for the second time to obtain the alkali-activated bentonite slurry steel slag foam concrete.

[0040] The third aspect of the present invention provides the use of the above-mentioned alkali-activated bentonite slurry steel slag foam concrete in the field of construction engineering.

[0041] The technical solutions described in the present invention, unless otherwise specified, are all conventional solutions in the art, and the reagents or raw materials used, unless otherwise specified, are purchased from commercial channels or have been disclosed.

[0042] The cement used in the embodiment of the present invention is PO 42.5, the mineral powder used is S105 grade high-quality mineral powder, the steel slag powder used is 200-300 mesh converter slag steel slag powder, and the particle size of the manganese tailings used is 0-1mm.

[0043] The test methods involved in the present invention: 7d compressive strength and 28d compressive strength tests refer to the "Foamed Concrete" (JG / T 266) standard, and 28d thermal conductivity test refers to the "Foamed Concrete" (JG / T 266) standard.

[0044] In the present invention, the dry density is equal to the empirical coefficient ψ×(mass of cement per cubic meter + mass of bentonite slurry per cubic meter + mass of mineral powder per cubic meter + mass of steel slag powder per cubic meter + mass of manganese tailings per cubic meter + mass of NaOH per cubic meter); ψ is the scaling of the empirical coefficient and takes a value of 1.2.

[0045] The flow chart of preparing alkali activated bentonite slurry steel slag foam concrete according to the present invention is as follows Figure 1 As shown; the technical solution provided by the present invention is described in detail below in conjunction with the embodiments, but they should not be understood as limiting the scope of protection of the present invention.

[0046] Example 1

[0047] This embodiment provides an alkali-activated bentonite slurry steel slag foam concrete with a designed dry density of 700 kg / m 3 , every 1m 3 It contains the following components: 437.5kg of cement, 29.17kg of expanded soil slurry, 58.3kg of mineral powder, 29.17kg of steel slag powder, 0.875kg of NaOH, 29.17kg of manganese tailings, 262.2kg of water and 31.16kg of foam.

[0048] The preparation method of the above-mentioned activated bentonite slurry steel slag foam concrete comprises the following steps:

[0049] Step 1, according to the above raw material dosage, NaOH is added into water, mixed and stirred to obtain NaOH solution, and mineral powder, steel slag powder, manganese tailings and NaOH solution are stirred and mixed to obtain alkali-activated solid waste slurry;

[0050] The bentonite was passed through a 0.075 mm sieve and then dried, mixed with water in a volume ratio of 1:15, put into a high-speed mixer, stirred evenly, and then allowed to stand for 24 hours to obtain a bentonite slurry.

[0051] The foaming agent and water were mixed in a mass ratio of 1:30 and stirred at a high speed (speed of 700 rpm). After stirring, a foaming machine was used to foam the mixture to obtain uniform and stable foam.

[0052] Step 2: Mix cement, alkali-activated solid waste slurry and bentonite slurry, use a forced mixer for the first stirring for 5 minutes to obtain a cementitious material mixed slurry, add foam to the cementitious material mixed slurry, and use a forced mixer for the second stirring for 10 minutes to obtain a foamed cementitious mixed slurry (i.e., alkali-activated bentonite slurry steel slag foam concrete).

[0053] Step 3: pouring, demoulding, and curing to the age according to the standard to obtain alkali-activated bentonite slurry steel slag foam concrete test blocks.

[0054] The alkali-activated bentonite slurry steel slag foam concrete prepared in this embodiment has a 7d compressive strength of 1.7 MPa, a 28d compressive strength of 2.05 MPa, and a 28d thermal conductivity of 0.1635 W / (m·K).

[0055] Example 2

[0056] This embodiment provides an alkali-activated bentonite slurry steel slag foam concrete with a designed dry density of 700 kg / m 3 , every 1m 3 It contains the following components: 425.8kg of cement, 40.83kg of expanded soil slurry, 58.3kg of mineral powder, 29.17kg of steel slag powder, 0.875kg of NaOH, 29.17kg of manganese tailings, 262.2kg of water and 30.76kg of foam.

[0057] The preparation method of alkali-activated bentonite slurry steel slag foam concrete in this embodiment is the same as that in Example 1;

[0058] The alkali-activated bentonite slurry steel slag foam concrete prepared in this embodiment has a 7d compressive strength of 1.64 MPa, a 28d compressive strength of 2.0 MPa, and a 28d thermal conductivity of 0.1621 W / (m·K).

[0059] Example 3

[0060] This embodiment provides an alkali-activated bentonite slurry steel slag foam concrete with a designed dry density of 700 kg / m 3 , every 1m 3 It contains the following components: 408.3kg of cement, 58.3kg of expanded soil slurry, 58.3kg of mineral powder, 29.17kg of steel slag powder, 0.875kg of NaOH, 29.17kg of manganese tailings, 262.2kg of water and 30.15kg of foam.

[0061] The preparation method of alkali-activated bentonite slurry steel slag foam concrete in this embodiment is the same as that in Example 1;

[0062] The alkali-activated bentonite slurry steel slag foam concrete prepared in this embodiment has a 7d compressive strength of 1.55 MPa, a 28d compressive strength of 1.9 MPa, and a 28d thermal conductivity of 0.1609 W / (m·K).

[0063] Comparative Example 1

[0064] This comparative example provides a foamed concrete with a designed dry density of 700 kg / m 3 , every 1m 3 Contains the following components: 583.3 kg cement, 262.2 kg water and 32.31 kg foam.

[0065] The preparation method of this comparative example is as follows:

[0066] The cement and water were mixed and stirred for the first time in a forced mixer for 5 minutes to obtain a cement mixed slurry. After the foam was added, the mixture was stirred for the second time in a forced mixer for 10 minutes to obtain a foamed gelled mixed slurry (i.e., foamed concrete). The mixture was poured, demoulded, and cured to the age according to the standard to obtain a foamed concrete test block.

[0067] The preparation method of the foam in this comparative example is the same as that in Example 1.

[0068] The foamed concrete prepared in this comparative example has a 7d compressive strength of 1.2 MPa, a 28d compressive strength of 1.73 MPa, and a 28d thermal conductivity of 0.1795 W / (m·K).

[0069] Comparative Example 2

[0070] The only difference from Example 3 is that the manganese tailings are replaced by cement of equal mass.

[0071] The foamed concrete prepared in this comparative example has a 7d compressive strength of 1.19 MPa, a 28d compressive strength of 1.66 MPa, and a 28d thermal conductivity of 0.1775 W / (m·K).

[0072] Comparative Example 3

[0073] The only difference from Example 3 is that the amount of cement added is 379.2 kg and the amount of manganese tailings added is 58.3 kg (ie, part of the cement is replaced by an equal mass of manganese tailings).

[0074] The foamed concrete prepared in this comparative example has a 7d compressive strength of 1.15 MPa, a 28d compressive strength of 1.75 MPa, and a 28d thermal conductivity of 0.1755 W / (m·K).

[0075] Figure 2 This is the SEM image of the alkali-activated bentonite slurry steel slag foam concrete prepared in Example 1.

[0076] Figure 3 This is the SEM image of the alkali-activated bentonite slurry steel slag foam concrete prepared in Example 2.

[0077] Figure 4 This is the SEM image of the alkali-activated bentonite slurry steel slag foam concrete prepared in Example 3.

[0078] Figure 5 This is the SEM image of the foamed concrete prepared in Comparative Example 1 (conventional foamed concrete without solid waste materials and alkali activator).

[0079] Figure 6 This is the SEM image of the foamed concrete prepared in Comparative Example 2 (foamed concrete without fine aggregate from manganese tailings).

[0080] Figure 7 This is the SEM image of the foamed concrete prepared in Comparative Example 3 (foamed concrete mixed with excessive manganese tailings fine aggregate).

[0081] like Figure 2-Figure 4 As shown, in the foamed concrete prepared in Examples 1-3, most of the pores are small pores and the structure is the most compact.

[0082] like Figure 5 As shown in the figure, when the amount of cementitious materials is the same, the internal pore distribution of the conventional foam concrete structure without solid waste materials and bentonite slurry is relatively uniform, but there are a small number of connected pores.

[0083] like Figure 6 As shown, the foamed concrete (Comparative Example 2) mixed with only bentonite slurry, slag powder and alkali activator but without manganese tailings slag fine aggregate has a relatively uniform distribution of structural pores, but there are a small number of large pores and connected pores inside the structure.

[0084] Figure 7 and Figure 4By comparison, it can be seen that the foam concrete with excessive manganese tailings (Comparative Example 3) has an increased proportion of large pores, a larger difference in pore size, and more connected pores.

[0085] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. An alkali-activated bentonite slurry steel slag foam concrete, characterized in that: Calculated by weight, the raw materials include 400-440 parts of cement, 25-60 parts of expanded soil slurry, 55-60 parts of mineral powder, 25-30 parts of steel slag powder, 0.8-1 parts of alkali, 25-30 parts of manganese tailings, 260-265 parts of water and 30-32 parts of foam.

2. The alkali-activated bentonite slurry steel slag foam concrete according to claim 1, characterized in that: The cement is PO 42.5; the alkali is NaOH.

3. The alkali-activated bentonite slurry steel slag foam concrete according to claim 1, characterized in that: The expanded soil slurry is prepared by mixing bentonite and water; the volume ratio of the bentonite to the water is 1:

15.

4. The alkali-activated bentonite slurry steel slag foam concrete according to claim 1, characterized in that: The foam is prepared by mixing a foaming agent and water in a mass ratio of 1:30, stirring, and foaming.

5. The alkali-activated bentonite slurry steel slag foam concrete according to claim 1, characterized in that: The mineral powder is S105 grade mineral powder; the steel slag powder is 200-300 mesh converter slag steel slag powder; the particle size of the manganese tailings is 0-1mm, and is not 0.

6. A method for preparing alkali-activated bentonite slurry steel slag foam concrete according to any one of claims 1 to 5, characterized in that: The following steps are involved: Step 1, mixing alkali and water according to mass fractions to obtain an alkali solution, adding mineral powder, steel slag powder, and manganese tailings to the alkali solution and mixing to obtain an alkali-activated solid waste slurry; Step 2: Mix cement, alkali-activated solid waste slurry and bentonite slurry and stir them for the first time to obtain a cementitious material mixed slurry, add foam to the cementitious material mixed slurry and stir them for the second time to obtain the alkali-activated bentonite slurry steel slag foam concrete.

7. Application of the alkali-activated bentonite slurry steel slag foam concrete as described in any one of claims 1 to 5 in the field of construction engineering.

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