A method for preparing a large-volume concrete composite admixture using solid waste residue as raw material

Abstract

The present invention belongs to the technical field of concrete preparation, and more specifically, relates to a method for preparing a large-volume concrete composite admixture using solid waste as raw materials. The raw materials of the large-volume concrete composite admixture provided by the present invention include: activated and modified phosphogypsum, calcined and finely ground lithium slag powder, as well as silica fume, redispersible latex powder, quartz powder and sodium silicate, which are added to concrete as cement substitutes without affecting the compressive strength, static elastic modulus, impermeability, frost resistance and other properties of the concrete.

Description

Technical Field

[0001] The invention belongs to the technical field of concrete preparation, and more specifically relates to a method for preparing a large-volume concrete composite admixture using solid waste residue as a raw material. Background Art

[0002] Green low-carbon concrete is a sustainable building material that can ensure strength and durability while minimizing environmental pollution. Traditional concrete consumes a large amount of cement every year, and the production of cement requires a large amount of limestone to be mined every year. In addition, a large amount of carbon dioxide is generated during the production process, causing serious damage to the ecological environment.

[0003] As an industrial waste, the accumulation of phosphogypsum not only occupies a large amount of land, but also pollutes the soil and the environment if piled for a long time. 2 and Al 2 O 3 Chemical substances such as lithium slag have high volcanic ash activity and can be used as mineral admixtures in cement concrete. The activity of lithium slag cannot be fully released when directly applied to concrete. In addition, lithium slag powder has a porous structure and a large specific surface area, which makes it require a large amount of water, resulting in reduced fluidity of concrete.

[0004] How to use phosphogypsum and lithium slag as the main raw materials to prepare large-volume concrete composite admixtures, which can not only make full use of solid wastes such as phosphogypsum and lithium slag, but also promote the development of green and low-carbon concrete, has become a difficult problem that technical personnel in this field urgently need to overcome. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing a large-volume concrete composite admixture using solid waste as a raw material, so as to solve the problems existing in the above-mentioned prior art.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] One of the technical solutions of the present invention is to provide a large-volume concrete composite admixture using solid waste as raw materials, wherein the raw materials include, by weight:

[0008] 30-45 parts of phosphogypsum, 25-35 parts of lithium slag powder, 5-15 parts of silica fume, 5-10 parts of redispersible latex powder, 5-10 parts of quartz powder and 5-20 parts of sodium silicate;

[0009] The phosphogypsum is obtained by activating and modifying the phosphogypsum raw material;

[0010] The lithium slag powder is obtained by calcining and fine grinding lithium slag as raw material.

[0011] Furthermore, the activation and modification treatment step includes:

[0012] The phosphogypsum and lime are uniformly mixed, and the pretreated phosphogypsum is obtained after a first standing, drying, and a first ball milling;

[0013] The pretreated phosphogypsum, sodium persulfate and sodium hydroxide solution are uniformly mixed, and the activation modification treatment is completed after a second standing, calcination and a second ball milling;

[0014] The concentration of the sodium hydroxide solution is 28-32 wt.%.

[0015] Optionally, the mass ratio of the phosphogypsum to lime is 4-6:1-2.

[0016] Optionally, the first static environmental parameters are: temperature of 15-25°C, humidity of not less than 60%, and time of 22-26 h.

[0017] Optionally, the drying temperature is 40-50°C.

[0018] Optionally, the first ball milling time is 25-35 min, and the specific surface area of ​​the pretreated phosphogypsum obtained after ball milling is about 280-340 m 2 / kg.

[0019] Optionally, the mass ratio of the pretreated phosphogypsum, sodium persulfate and sodium hydroxide solution is (95-105):(1-3):(8-12).

[0020] Optionally, the second static environmental parameters are: temperature of 15-25°C, humidity of not less than 60%, and time of 46-50 h.

[0021] Optionally, the calcination temperature is 140-160° C. and the calcination time is 40-50 min.

[0022] Optionally, the second ball milling time is 35-45 min, and the surface area of ​​the phosphogypsum obtained after ball milling is about 290-350 m 2 / kg.

[0023] Furthermore, the calcination and fine grinding process comprises:

[0024] The lithium slag was calcined at 850-950 °C for 4.5-5.5 h and then ground to a specific surface area of ​​750-850 m 2 / kg.

[0025] The second technical solution of the present invention is to provide a method for preparing the large-volume concrete composite admixture using solid waste as raw material, the steps comprising:

[0026] Mix phosphogypsum, lithium slag powder, silica fume, redispersible latex powder, quartz powder and sodium silicate according to the above proportions and stir evenly to obtain the product.

[0027] The third technical solution of the present invention is to provide a large amount of concrete composite admixture using solid waste as raw material to replace cement in the preparation of concrete.

[0028] Furthermore, the concrete raw materials used in the concrete preparation include the above-mentioned large-volume concrete composite admixture using solid waste as raw materials;

[0029] Based on the total mass of the large-volume concrete composite admixture using solid waste as raw materials and cement being 100 parts, the amount of the large-volume concrete composite admixture using solid waste as raw materials is 50-60 parts.

[0030] The present invention discloses the following technical effects:

[0031] The invention is to treat the activation and modification of the raw material of phosphogypsum, and then use lithium slag as the raw material, calcined and finely ground, and then compound it with silica fume, redispersible latex powder, quartz powder and sodium silicate to form a large-volume concrete admixture, and the usage amount is 50-60% of the cement usage amount. The lithium slag powder has high volcanic ash activity, and the phosphogypsum and sodium silicate are used as alkaline activators to promote the early hydration of lithium slag powder and silica fume, improve the strength of concrete, and the redispersible latex powder increases the cohesion between particles and improves the early strength of concrete. In addition to having good volcanic ash activity, the silica fume has a large specific surface area so that it can better fill the gaps between particles, make the concrete system more compact, and improve the concrete impermeability. The quartz powder adopts ultrafine powder with a fineness of 800 meshes, which can fill smaller pores, release more free water, reduce the viscosity of concrete, and improve the fluidity of concrete.

[0032] The present invention combines activated and modified phosphogypsum, calcined and finely ground lithium slag with other components, which can not only replace cement in large amounts to achieve a green and low-carbon effect, but also does not affect the compressive strength, static elastic modulus, impermeability, frost resistance and other properties of concrete. DETAILED DESCRIPTION

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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 those skilled in the art. The present invention description and examples are exemplary only.

[0037] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0038] It should be pointed out that the matters not described in detail in the present invention are conventional operating means in the art and are not the focus of the present invention.

[0039] Unless otherwise specified, the raw materials and reagents used in the specific embodiments of the present invention are all commercially available products, and their sources do not affect the technical effects of the present invention.

[0040] In the specific embodiment of the present invention, the phosphogypsum before activation and modification is provided by a chemical enterprise in Mianyang, Sichuan: the main component is CaSO 4 ·2H 2 0, of which CaO content is 38.59%, SiO 2 Content 1.53 %,Fe 2 O 3 Content 0.28 %,Al 2 O 3 Content 0.39%, P 2 O 5 Content 1.82%, SO 3 Content 40.62%, etc.

[0041] In the specific embodiment of the present invention, the lithium slag before calcination and fine grinding is provided by Sichuan Qinggu New Materials Co., Ltd.

[0042] The silica fume used in the specific embodiment of the present invention is provided by Chengdu Excellent Sifang Environmental Technology Co., Ltd.: the silica content is 93.8%, the specific surface area is 20000 m 2 / ㎏, 28-day activity index 120%; redispersible latex powder is provided by Olais (Tianjin) Chemical Co., Ltd., product model: 5067; quartz powder is provided by Henan Borun Casting Materials Co., Ltd., silicon dioxide content 99.98%, density 2.65 g / cm 3 , Mohs hardness is 7, and the average particle size is 800 mesh; sodium silicate is provided by Taixing Yueda Industrial Co., Ltd., and its main component is sodium metasilicate pentahydrate, which is a white powder and easily soluble in water.

[0043] The polycarboxylate water reducer used in the specific embodiment of the present invention is provided by Shijiazhuang Changan Yucai Building Materials Co., Ltd., and the brand is GK-3000 water reducer; the ordinary Portland cement used is provided by Sichuan Esheng Cement, which is PO 42.5 cement; and the fly ash used is Huaneng F Class II ash.

[0044] Unless otherwise specified, the "parts" in the specific embodiments of the present invention are all "parts by mass", and the "room temperature" and "normal temperature" involved all refer to 20-30°C.

[0045] Example 1

[0046] The preparation steps of large-volume concrete composite admixture using solid waste as raw material include:

[0047] S1. Mix the phosphogypsum raw material and lime in a mass ratio of 5:1, let it stand for 24 h at a temperature of 20±5°C and a humidity of not less than 60%, dry it (temperature of 45°C), and grind it in a ball mill for 30 min to obtain pretreated phosphogypsum. The surface area of ​​the pretreated phosphogypsum was 310 m 2 / kg;

[0048] S2: The pretreated phosphogypsum obtained in step S1, sodium persulfate and sodium hydroxide solution (concentration of 30 wt.%) were mixed uniformly in a mass ratio of 100:2:10, and allowed to stand for 48 h at a temperature of 20±5°C and a humidity of not less than 60%, and then calcined at 150°C for 45 min, and ground by a ball mill for 40 min to obtain phosphogypsum with a surface area of ​​320 m 2 / kg;

[0049] S3, calcining the lithium slag at 900 °C for 5 h, and then grinding it into powder with a specific surface area of ​​750-850m 2 / kg of lithium slag powder;

[0050] S4, raw material ratio: 40 parts of phosphogypsum prepared in step S2, 30 parts of lithium slag powder prepared in step S3, 5 parts of silica fume, 7.5 parts of 800 mesh quartz powder, 7.5 parts of redispersible latex powder and 10 parts of sodium silicate;

[0051] S5. Mix the raw materials prepared in step S4 and stir them evenly to obtain a large-volume concrete composite admixture.

[0052] Example 2

[0053] Compared with Example 1, the difference is that the raw material ratio of step S4 is: 35 parts of phosphogypsum prepared in step S2, 35 parts of lithium slag powder prepared in step S3, 8 parts of silica fume, 5 parts of 800 mesh quartz powder, 5 parts of redispersible latex powder and 12 parts of sodium silicate. The specific steps include:

[0054] S1. Mix the phosphogypsum raw material and lime in a mass ratio of 5:1, let it stand for 24 h at a temperature of 20±5°C and a humidity of not less than 60%, dry it (temperature of 45°C), and grind it in a ball mill for 30 min to obtain pretreated phosphogypsum. The surface area of ​​the pretreated phosphogypsum was 310 m 2 / kg;

[0055] S2: The pretreated phosphogypsum obtained in step S1, sodium persulfate and sodium hydroxide solution (concentration of 30 wt.%) were mixed uniformly in a mass ratio of 100:2:10, and allowed to stand for 48 h at a temperature of 20±5°C and a humidity of not less than 60%, and then calcined at 150°C for 45 min, and ground by a ball mill for 40 min to obtain phosphogypsum with a surface area of ​​320 m 2 / kg;

[0056] S3, calcining the lithium slag at 900 °C for 5 h, and then grinding it into powder with a specific surface area of ​​750-850m 2 / kg of lithium slag powder;

[0057] S4, raw material ratio: 35 parts of phosphogypsum prepared in step S2, 35 parts of lithium slag powder prepared in step S3, 8 parts of silica fume, 5 parts of 800 mesh quartz powder, 5 parts of redispersible latex powder and 12 parts of sodium silicate;

[0058] S5. Mix the raw materials prepared in step S4 and stir them evenly to obtain a large-volume concrete composite admixture.

[0059] Example 3

[0060] Compared with Example 1, the difference is that the raw material ratio of step S4 is: 45 parts of phosphogypsum prepared in step S2, 30 parts of lithium slag powder prepared in step S3, 10 parts of silica fume, 5 parts of 800 mesh quartz powder, 5 parts of redispersible latex powder and 5 parts of sodium silicate. The specific steps include:

[0061] S1. Mix the phosphogypsum raw material and lime in a mass ratio of 5:1, let it stand for 24 h at a temperature of 20±5°C and a humidity of not less than 60%, dry it (temperature of 45°C), and grind it in a ball mill for 30 min to obtain pretreated phosphogypsum. The surface area of ​​the pretreated phosphogypsum was 310 m 2 / kg;

[0062] S2: The pretreated phosphogypsum obtained in step S1, sodium persulfate and sodium hydroxide solution (concentration of 30 wt.%) were mixed uniformly in a mass ratio of 100:2:10, and allowed to stand for 48 h at a temperature of 20±5°C and a humidity of not less than 60%, and then calcined at 150°C for 45 min, and ground by a ball mill for 40 min to obtain phosphogypsum with a surface area of ​​320 m 2 / kg;

[0063] S3, calcining the lithium slag at 900 °C for 5 h, and then grinding it into powder with a specific surface area of ​​750-850m 2 / kg of lithium slag powder;

[0064] S4, raw material ratio: 45 parts of phosphogypsum prepared in step S2, 30 parts of lithium slag powder prepared in step S3, 10 parts of silica fume, 5 parts of 800 mesh quartz powder, 5 parts of redispersible latex powder and 5 parts of sodium silicate;

[0065] S5. Mix the raw materials prepared in step S4 and stir them evenly to obtain a large-volume concrete composite admixture.

[0066] Example 4

[0067] The preparation steps of concrete with large amount of composite admixture include:

[0068] S1. Raw material preparation: 6.16 parts of ordinary Portland cement, 9.24 parts of high-volume concrete composite admixture prepared in Example 1 (replacing 60% of cement dosage), 33.5 parts of machine-made sand, 8.9 parts of 5-10 mm crushed stone, 22.2 parts of 10-20 mm crushed stone, 13.3 parts of 16-31.5 mm crushed stone, 6.7 parts of water and 0.16 parts of polycarboxylate water reducer;

[0069] S2. Mix the raw materials prepared in step S1, and stir them in a compulsory mixer for 2 minutes to obtain a large-volume composite admixture concrete.

[0070] Example 5

[0071] Compared with Example 4, the difference is that the large-volume concrete composite admixture used is prepared from Example 2, and the specific steps include:

[0072] S1. Raw material preparation: 6.16 parts of ordinary Portland cement, 9.24 parts of high-volume concrete composite admixture prepared in Example 2 (replacing 60% of the cement dosage), 33.5 parts of machine-made sand, 8.9 parts of 5-10 mm crushed stone, 22.2 parts of 10-20 mm crushed stone, 13.3 parts of 16-31.5 mm crushed stone, 6.7 parts of water and 0.16 parts of polycarboxylate water reducer;

[0073] S2. Mix the raw materials prepared in step S1, and stir them in a compulsory mixer for 2 minutes to obtain a large-volume composite admixture concrete.

[0074] Example 6

[0075] Compared with Example 4, the difference is that the large-volume concrete composite admixture used is prepared from Example 3, and the specific steps include:

[0076] S1. Raw material preparation: 6.16 parts of ordinary Portland cement, 9.24 parts of high-volume concrete composite admixture prepared in Example 3 (replacing 60% of the cement dosage), 33.5 parts of machine-made sand, 8.9 parts of 5-10 mm crushed stone, 22.2 parts of 10-20 mm crushed stone, 13.3 parts of 16-31.5 mm crushed stone, 6.7 parts of water and 0.16 parts of polycarboxylate water reducer;

[0077] S2. Mix the raw materials prepared in step S1, and stir them in a compulsory mixer for 2 minutes to obtain a large-volume composite admixture concrete.

[0078] Example 7

[0079] Compared with Example 6, the difference is that the amount of ordinary Portland cement is adjusted to 6.93 parts, and the amount of the large-volume concrete composite admixture prepared in Example 3 is adjusted to 8.47 parts. The specific steps include:

[0080] S1. Raw material preparation: 6.93 parts of ordinary Portland cement, 8.47 parts of high-volume concrete composite admixture prepared in Example 3 (replacing 55% of cement), 33.5 parts of machine-made sand, 8.9 parts of 5-10 mm crushed stone, 22.2 parts of 10-20 mm crushed stone, 13.3 parts of 16-31.5 mm crushed stone, 6.7 parts of water and 0.16 parts of polycarboxylate water reducer;

[0081] S2. Mix the raw materials prepared in step S1, and stir them in a compulsory mixer for 2 minutes to obtain a large-volume composite admixture concrete.

[0082] Example 8

[0083] Compared with Example 6, the difference is that the amount of ordinary Portland cement is adjusted to 7.7 parts, the amount of the large-volume concrete composite admixture prepared in Example 3 is adjusted to 7.7 parts, and the specific steps include:

[0084] S1. Raw material preparation: 7.7 parts of ordinary Portland cement, 7.7 parts of high-volume concrete composite admixture prepared in Example 3 (replacing 50% of the cement dosage), 33.5 parts of machine-made sand, 8.9 parts of 5-10 mm crushed stone, 22.2 parts of 10-20 mm crushed stone, 13.3 parts of 16-31.5 mm crushed stone, 6.7 parts of water and 0.16 parts of polycarboxylate water reducer;

[0085] S2. Mix the raw materials prepared in step S1, and stir them in a compulsory mixer for 2 minutes to obtain a large-volume composite admixture concrete.

[0086] Comparative Example 1

[0087] The preparation steps of ordinary concrete include:

[0088] S1. Raw materials: 15.4 parts of ordinary Portland cement, 33.5 parts of machine-made sand, 8.9 parts of 5-10 mm crushed stone, 22.2 parts of 10-20 mm crushed stone, 13.3 parts of 16-31.5 mm crushed stone, 6.7 parts of water and 0.16 parts of polycarboxylate water reducer;

[0089] S2. Mix the raw materials in step S1 in a compulsory mixer for 2 min to obtain ordinary concrete.

[0090] Comparative Example 2

[0091] The preparation steps of high-volume fly ash concrete include:

[0092] S1. Raw materials: 6.16 parts of ordinary Portland cement, 9.24 parts of fly ash (replacing 60% of cement), 33.5 parts of machine-made sand, 8.9 parts of 5-10 mm crushed stone, 22.2 parts of 10-20 mm crushed stone, 13.3 parts of 16-31.5 mm crushed stone, 6.7 parts of water and 0.16 parts of polycarboxylate water reducer;

[0093] S2. Mix the raw materials in step S1 in a compulsory mixer for 2 min to obtain a large amount of fly ash concrete.

[0094] Comparative Example 3

[0095] Compared with Example 3, the difference is that the phosphogypsum is replaced by an equal amount of phosphogypsum raw material that has not been activated and modified (i.e., the phosphogypsum raw material used in step S1 in Example 3), and the specific steps include:

[0096] S1. Dry the phosphogypsum raw material (temperature is 45 °C) and grind it into powder with a ball mill until the surface area is 320 m 2 / kg;

[0097] S2, calcining the lithium slag at 900 °C for 5 h, and then grinding it into a powder with a specific surface area of ​​750-850 m 2 / kg of lithium slag powder;

[0098] S3, raw material ratio: 45 parts of phosphogypsum ground in step S1, 30 parts of lithium slag powder obtained in step S2, 10 parts of silica fume, 5 parts of 800 mesh quartz powder, 5 parts of redispersible latex powder and 5 parts of sodium silicate;

[0099] S4, mixing the raw materials prepared in step S3, stirring evenly, and obtaining a large-volume concrete composite admixture.

[0100] Comparative Example 4

[0101] Compared with Example 3, the difference is that the lithium slag powder is replaced by an equal amount of lithium slag that has not been calcined and finely ground (i.e., the lithium slag used in step S2 in Example 3). The specific steps include:

[0102] S1. Mix the phosphogypsum raw material and lime in a mass ratio of 5:1, let it stand for 24 h at a temperature of 20±5°C and a humidity of not less than 60%, dry it (the temperature is 45°C and then grind it in a ball mill for 30 min to obtain pretreated phosphogypsum with a surface area of ​​310 m 2 / kg;

[0103] S2: The pretreated phosphogypsum obtained in step S1, sodium persulfate and sodium hydroxide solution (concentration of 30 wt.%) were mixed uniformly in a mass ratio of 100:2:10, and allowed to stand for 48 h at a temperature of 20±5°C and a humidity of not less than 60%, and then calcined at 150°C for 45 min, and ground by a ball mill for 40 min to obtain phosphogypsum with a surface area of ​​320 m 2 / kg;

[0104] S3, grind the lithium slag into powder with a specific surface area of ​​750-850 m 2 / kg of lithium slag;

[0105] S4, raw material ratio: 45 parts of phosphogypsum obtained in step S2, 30 parts of lithium slag obtained in step S3, 10 parts of silica fume, 5 parts of 800 mesh quartz powder, 5 parts of redispersible latex powder and 5 parts of sodium silicate;

[0106] S5. Mix the raw materials prepared in step S4 and stir them evenly to obtain a large-volume concrete composite admixture.

[0107] Comparative Example 5

[0108] Compared with Example 3, the difference is that the phosphogypsum is replaced by an equal amount of phosphogypsum raw material that has not been activated and modified (i.e., the phosphogypsum raw material used in step S1 in Example 3), and the lithium slag powder is replaced by an equal amount of lithium slag that has not been calcined and finely ground (i.e., the lithium slag used in step S2 in Example 3). The specific steps include:

[0109] S1. Dry the phosphogypsum raw material and grind it into powder with a ball mill until the surface area is 320 m 2 / kg;

[0110] S2, grind the lithium slag into powder with a specific surface area of ​​750-850 m 2 / kg of lithium slag;

[0111] S3, raw material ratio: 45 parts of phosphogypsum ground in step S1, 30 parts of lithium slag obtained in step S2, 10 parts of silica fume, 5 parts of 800 mesh quartz powder, 5 parts of redispersible latex powder and 5 parts of sodium silicate;

[0112] S4, mixing the raw materials prepared in step S3, stirring evenly, and obtaining a large-volume concrete composite admixture.

[0113] Comparative Example 6

[0114] Compared with Example 6, the difference is that the large-volume concrete composite admixture prepared in Example 3 is replaced with an equal amount of the large-volume concrete composite admixture prepared in Comparative Example 3. The specific steps include:

[0115] S1. Raw material preparation: 6.16 parts of ordinary Portland cement, 9.24 parts of large-volume concrete composite admixture prepared in Comparative Example 3 (replacing 60% of cement dosage), 33.5 parts of machine-made sand, 8.9 parts of 5-10 mm crushed stone, 22.2 parts of 10-20 mm crushed stone, 13.3 parts of 16-31.5 mm crushed stone, 6.7 parts of water and 0.16 parts of polycarboxylate water reducer;

[0116] S2. Mix the raw materials prepared in step S1, and stir them in a compulsory mixer for 2 minutes to obtain a large-volume composite admixture concrete.

[0117] Comparative Example 7

[0118] Compared with Example 6, the difference is that the large-volume concrete composite admixture prepared in Example 3 is replaced with an equal amount of the large-volume concrete composite admixture prepared in Comparative Example 4, and the specific steps include:

[0119] S1. Raw material preparation: 6.16 parts of ordinary Portland cement, 9.24 parts of high-volume concrete composite admixture prepared in Comparative Example 4 (replacing 60% of cement dosage), 33.5 parts of machine-made sand, 8.9 parts of 5-10 mm crushed stone, 22.2 parts of 10-20 mm crushed stone, 13.3 parts of 16-31.5 mm crushed stone, 6.7 parts of water and 0.16 parts of polycarboxylate water reducer;

[0120] S2. Mix the raw materials prepared in step S1, and stir them in a compulsory mixer for 2 minutes to obtain a large-volume composite admixture concrete.

[0121] Comparative Example 8

[0122] Compared with Example 6, the difference is that the large-volume concrete composite admixture prepared in Example 3 is replaced with an equal amount of the large-volume concrete composite admixture prepared in Comparative Example 5, and the specific steps include:

[0123] S1. Raw materials preparation: 6.16 parts of ordinary Portland cement, 9.24 parts of high-volume concrete composite admixture prepared in Comparative Example 5 (replacing 60% of cement dosage), 33.5 parts of machine-made sand, 8.9 parts of 5-10 mm crushed stone, 22.2 parts of 10-20 mm crushed stone, 13.3 parts of 16-31.5 mm crushed stone, 6.7 parts of water and 0.16 parts of polycarboxylate water reducer;

[0124] S2. Mix the raw materials prepared in step S1, and stir them in a compulsory mixer for 2 minutes to obtain a large-volume composite admixture concrete.

[0125] Test example

[0126] According to the standard GB / T 50081 "Standard for Test Methods of Physical and Mechanical Properties of Concrete" and the standard GB / T 50082 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete", the concretes prepared in Examples 4 to 8, Comparative Examples 1 to 2 and Comparative Examples 6 to 8 were tested, and the indicators are shown in Table 1:

[0127] Table 1

[0128]

[0129] In Table 1, it can be seen from the data comparison of Comparative Example 1 and Comparative Example 2 that fly ash, as a commonly used concrete admixture, replaces cement in large amounts, and the concrete strength increases slowly, while causing a decrease in the frost resistance and impermeability grades. In Examples 4-8, after the composite admixtures prepared by Examples 1-3 of the present invention are used to replace part of the cement, there is no adverse effect on the concrete compressive strength, static elastic modulus, impermeability, frost resistance and other properties, and some performance indicators are even better. In Comparative Examples 6-8, Comparative Example 6 changes the phosphogypsum component in the raw materials of the added large-volume concrete composite admixture, and in Comparative Example 7, the lithium slag powder component in the raw materials of the added large-volume concrete composite admixture is changed. In Comparative Example 8, these two components are changed at the same time, which not only causes a significant decrease in the concrete strength grade, but also a significant decrease in the elastic modulus, frost resistance and impermeability grades, resulting in a shortened concrete life.

[0130] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0131] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A large-volume concrete composite admixture using solid waste as raw material, characterized in that: By mass, the raw materials include: 30-45 parts of phosphogypsum, 25-35 parts of lithium slag powder, 5-15 parts of silica fume, 5-10 parts of redispersible latex powder, 5-10 parts of quartz powder and 5-20 parts of sodium silicate; The phosphogypsum is obtained by activating and modifying the phosphogypsum raw material; The lithium slag powder is obtained by calcining and fine grinding lithium slag as raw material; The activation and modification treatment steps include: uniformly mixing phosphogypsum and lime, and obtaining pretreated phosphogypsum after a first standing, drying, and a first ball milling; uniformly mixing the pretreated phosphogypsum, sodium persulfate, and sodium hydroxide solution, and completing the activation and modification treatment after a second standing, calcination, and a second ball milling; the concentration of the sodium hydroxide solution is 28-32 wt.%.

2. The large-volume concrete composite admixture using solid waste as raw material as claimed in claim 1, characterized in that: The mass ratio of the phosphogypsum to lime is 4-6:1-2; and / or, the first static environmental parameters are: temperature of 15-25°C, humidity of not less than 60%, and time of 22-26 h.

3. The large-volume concrete composite admixture using solid waste as raw material as claimed in claim 1, characterized in that: The drying temperature is 40-50° C.; and / or the first ball milling time is 25-35 min.

4. The large-volume concrete composite admixture using solid waste as raw material as claimed in claim 1, characterized in that: The mass ratio of the pretreated phosphogypsum, sodium persulfate and sodium hydroxide solution is (95-105):(1-3):(8-12); and / or, the environmental parameters of the second static state are: temperature of 15-25°C, humidity of not less than 60%, and time of 46-50 h.

5. The large-volume concrete composite admixture using solid waste as raw material as claimed in claim 1, characterized in that: The calcination temperature is 140-160° C. and the time is 40-50 min; and / or the second ball milling time is 35-45 min.

6. The large-volume concrete composite admixture using solid waste as raw material as claimed in claim 1, characterized in that: The steps of calcining and fine grinding treatment include: The lithium slag was calcined at 850-950 °C for 4.5-5.5 h and then ground to a specific surface area of ​​750-850 m 2 / kg.

7. A method for preparing a large-volume concrete composite admixture using solid waste as raw material according to any one of claims 1 to 6, characterized in that the steps include: Mix phosphogypsum, lithium slag powder, silica fume, redispersible latex powder, quartz powder and sodium silicate according to the proportion and stir evenly to obtain the product.

8. Use of a large-volume concrete composite admixture made of solid waste as raw material as claimed in any one of claims 1 to 6 to replace cement in the preparation of concrete.

9. The use according to claim 8, characterized in that The concrete raw materials used in the concrete preparation include the large-volume concrete composite admixture using solid waste as raw materials; Based on the total mass of the large-volume concrete composite admixture using solid waste as raw materials and cement being 100 parts, the amount of the large-volume concrete composite admixture using solid waste as raw materials is 50-60 parts.

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