Aerated concrete repair agent based on low-carbon cementitious material production and preparation method

Abstract

The application discloses an aerated concrete repairing agent based on low-carbon cementing material production and a preparation method thereof, and belongs to the technical field of building materials. The aerated concrete repairing agent is used for solving the problems of high production cost, poor workability, low bonding strength with autoclaved aerated concrete board and poor aesthetic property in the prior art. The aerated concrete repairing agent comprises the following raw materials in parts by weight: aerated concrete waste 20-30 parts, low-carbon cementing material 5-10 parts, gypsum 5-10 parts, sand 50-70 parts, water-retaining agent 0.2-0.7 parts, water-reducing agent 0.01-0.02 parts and fiber 0.01-0.5 parts. The preparation method comprises the following steps: weighing the raw materials according to the proportion, discharging the raw materials from storage tanks and mixing the raw materials uniformly, adding water and stirring when the aerated concrete repairing agent is used, and using the aerated concrete repairing agent. The aerated concrete repairing agent has the advantages of high strength, good compatibility with aerated concrete, low production cost, easy construction, high bonding strength with autoclaved aerated concrete board and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of building materials, and particularly relates to an aerated concrete repair agent based on low-carbon cementitious material production and a preparation method thereof. BACKGROUND

[0002] The aerated concrete is a porous silicate concrete manufactured by taking cement, lime, sand (fly ash, stone powder, etc.), aluminum paste, additive, etc. as raw materials, and through ball milling, metering, stirring, pouring, gas expansion, static stopping, cutting, and autoclaved curing processes. With the wide application of the autoclaved aerated concrete, its use amount is increasing year by year. However, the total amount of damaged aerated concrete blanks, products and unqualified products is also increasing in the production and transportation process. In the transportation and construction process, the aerated concrete is prone to have defects such as missing corners, scratches and surface loss, which seriously affect the qualified rate and utilization rate of the product. In addition, the connecting parts, pre-embedded part holes and other material damage need to be filled during the construction process.

[0003] In the prior art, the ordinary Portland cement repair mortar is generally used as the aerated concrete repair agent, which has the advantages of high strength and good compatibility. However, it has problems such as high production cost, poor workability, low bonding strength with the autoclaved aerated concrete board and poor appearance, which has caused great trouble to the use of the aerated concrete and has also brought pollution to the environment.

[0004] Therefore, it is urgent for the technical personnel in the field to provide a repair agent for aerated concrete, which has high strength, good compatibility, low production cost, high bonding strength with the autoclaved aerated concrete board and good appearance. SUMMARY

[0005] One of the purposes of the present application is to provide an aerated concrete repair agent based on low-carbon cementitious material production, which solves the problems of high production cost, poor workability, low bonding strength with the autoclaved aerated concrete board and poor appearance of the aerated concrete repair agent in the prior art.

[0006] The second purpose of the present application is to provide a preparation method of the aerated concrete repair agent based on low-carbon cementitious material production.

[0007] To achieve the above purposes, the technical solution adopted by the present application is as follows:

[0008] The aerated concrete repair agent based on low-carbon cementitious material production provided by the present application comprises the following raw materials by weight:

[0009] Aerated concrete waste: 20-30 parts,

[0010] Low-carbon cementitious material: 5-10 parts,

[0011] Gypsum: 5-10 parts,

[0012] Sand: 50-70 parts,

[0013] Water retaining agent: 0.2-0.7 parts,

[0014] Water reducing agent: 0.01-0.02 parts,

[0015] Fiber: 0.01-0.5 parts.

[0016] In some embodiments of the present application, the low-carbon cementing material has a mineral composition of f-CaO 30-45 wt. %, 4-8 wt. %, C2S 40-50 wt. %, CaSO4 5-9 wt. %, C4AF 2-5 wt. %, and a specific surface area of 300-400 m 2 / kg.

[0017] The low-carbon cementing material of the present application includes free calcium oxide (f-CaO), C2S, a small amount of anhydrous calcium sulphoaluminate, and a high content of f-CaO. In the prior art, f-CaO is considered as a harmful component in all cement varieties, and the content of f-CaO is minimized in the selection of raw materials and the preparation process of products. The present application creatively uses the characteristics of f-CaO reacting with water to generate calcium hydroxide and releasing a large amount of heat, and uses a high content of f-CaO to release a large amount of heat during the preparation of the aerated concrete repair agent, thereby facilitating the increase of the temperature in the repair slurry and accelerating the hydration reaction of early strength minerals in the low-carbon cementing material; meanwhile, the generated calcium hydroxide is more likely to react with the hydration products of alumina gel and ferrum gel in the SO4 2- containing solution under suitable temperature and alkaline conditions to form needle-shaped ettringite embedded in the aerated concrete product, thereby promoting the faster setting and hardening of the repair agent and enabling the repaired area to have certain strength and adhesion.

[0018] The low-carbon cementing material of the present application also contains a small amount of early strength mineral calcium sulphoaluminate which can promote the faster setting and hardening of the aerated concrete repair agent and meet the hardening requirements of the product, and is superior to the setting and hardening of ordinary Portland cement.

[0019] The low-carbon cementing material of the present application also contains dicalcium silicate, which is beneficial to the stable growth of the late strength of the aerated concrete repair agent; and the appropriate amount of calcined CaSO4 in the present application can adjust the thickening process of the aerated concrete repair agent and the quality of the product.

[0020] In some embodiments of the present application, the aerated concrete waste is a dry powder mixture of powders of unqualified products in shape, damaged products or green body cutting in the production process of aerated concrete using the low-carbon cementing material as raw material. The mineral composition thereof includes SiO2: 50-75 wt %, Ca(OH)2: 0-25 wt %

[0021] The aerated concrete repair agent of this invention is made from low-carbon cementitious materials, sand, aerated concrete waste, water-retaining agents, water-reducing agents, and fibers. The low-carbon cementitious material replaces the commonly used silicate cement, lime, and gypsum raw materials in current production with a raw material that integrates all three. The waste generated during the production of aerated concrete contains a large amount of calcium hydroxide, ettringite, calcium carbonate, and small amounts of aluminum and iron adhesives. In sufficient gypsum and a saturated calcium hydroxide solution, ettringite is generated, resulting in a mixed slurry that sets quickly, has high strength, and a white appearance during the hardening process.

[0022] This invention combines the characteristics of novel low-carbon cementitious materials by adding appropriate amounts of gypsum, water-retaining agent, water-reducing agent, and fine sand to waste materials to prepare an aerated concrete repair agent.

[0023] In some embodiments of the present invention, the fine sand includes at least one of natural quartz sand, dolomite sand, and natural river sand, with SiO2 ≥ 80% in its chemical composition, and preferably, a specific surface area of ​​200–300 m². 2 / kg; preferably, the fine sand is white or off-white in color.

[0024] In some embodiments of the present invention, the gypsum is selected from any one or more of natural gypsum, anhydrite, and phosphogypsum;

[0025] Or / and the water-reducing agent is selected from polycarboxylate superplasticizers;

[0026] Or / and the water-retaining agent is selected from one or two of cellulose ether, methylcellulose ether, hydroxypropyl methylcellulose, polyacrylamide, and hydroxyethyl methylcellulose ether;

[0027] The fibers may be selected from one or two of polypropylene fibers, polyester fibers, and wood fibers.

[0028] This invention provides a method for preparing an aerated concrete repair agent based on low-carbon cementitious materials, comprising the following steps:

[0029] S1. Weigh out each raw material according to the proportions;

[0030] S2. Release all raw materials from the storage tank and mix them evenly;

[0031] S3. Just add water and stir before use.

[0032] In some embodiments of the present invention, the aerated concrete waste is crushed, ground, and screened before being used; preferably, the screening is performed through a 60-mesh sieve.

[0033] In some embodiments of the present invention, the consistency of the mixture stirred with water in step S3 is 90-110 mm and it is ready for use.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] This invention is scientifically designed and ingeniously conceived. It has high strength, good compatibility with aerated concrete, low production cost, is easy to construct, and has high bonding strength with autoclaved aerated concrete panels.

[0036] This invention has a high waste utilization rate, with aerated concrete waste accounting for up to 30% of the raw materials, effectively solving the problem of waste disposal for aerated concrete enterprises.

[0037] This invention effectively reduces production costs and promotes environmental protection and energy conservation. Currently, commercially available repair agents are mainly made of white ordinary silicate cement or white sulfoaluminate cement, with added water-retaining agents, water-reducing agents, and fibers. This invention primarily uses aerated concrete waste, low-carbon cementitious materials, and sand as raw materials, resulting in low costs and benefiting aerated concrete enterprises in terms of environmental protection and energy conservation.

[0038] Based on the characteristics of low-carbon cementitious materials, this invention adds an appropriate amount of gypsum and fine sand to waste materials, resulting in minimal color difference in the repaired products. Detailed Implementation

[0039] The following specific embodiments further illustrate the invention, but it should not be construed as limiting the scope of the invention to the following examples. Based on the inventive concept and the full text of the invention, the various technical features in the following examples can be appropriately combined, replaced, adjusted, or modified, which is obvious to those skilled in the art and still falls within the scope of protection of the invention.

[0040] The aerated concrete repair agent of the present invention, based on low-carbon cementitious materials, comprises the following raw materials in parts by weight:

[0041] Aerated concrete waste: 20-30 parts

[0042] Low-carbon cementitious materials: 5-10 parts

[0043] Plaster: 5-10 parts

[0044] Sand: 50-70 parts

[0045] Water-retaining agent: 0.2–0.7 parts,

[0046] Water-reducing agent: 0.01-0.02 parts,

[0047] Fiber: 0.01 to 0.5 parts.

[0048] The low-carbon cementitious material has a mineral composition of f-CaO 30-45 wt.%. 4–8 wt.%, C2S 40–50 wt.%, CaSO4 5–9 wt.%, C4AF 2–5 wt.%, specific surface area 300–400 m² 2 / kg.

[0049] The aerated concrete waste is a dry powder mixture made from powdered low-carbon cementitious materials produced during the aerated concrete production process, including materials from cut blanks, damaged products, or those with substandard shapes. Its mineral composition includes SiO2: 50–75 wt% and Ca(OH)2: 0–25 wt%.

[0050] The fine sand includes at least one of natural quartz sand, dolomite sand, and natural river sand, with a SiO2 content ≥ 80% in its chemical composition. Preferably, it has a specific surface area of ​​200–300 m². 2 / kg; preferably, the fine sand is white or off-white in color.

[0051] The gypsum is selected from any one or more of natural gypsum, anhydrite, and phosphogypsum;

[0052] Or / and the water-reducing agent is selected from polycarboxylate superplasticizers.

[0053] Or / and the water-retaining agent is selected from one or two of cellulose ether, methylcellulose ether, hydroxypropyl methylcellulose, polyacrylamide, and hydroxyethyl methylcellulose ether;

[0054] The fibers may be selected from one or two of polypropylene fibers, polyester fibers, and wood fibers.

[0055] The present invention relates to a method for preparing an aerated concrete repair agent based on low-carbon cementitious materials, comprising the following steps:

[0056] S1. Weigh out each raw material according to the proportions;

[0057] S2. Release all raw materials from the storage tank and mix them evenly;

[0058] S3. Just add water and stir before use.

[0059] The aerated concrete waste is crushed, ground, and screened before being used; preferably, the screening is done through a 60-mesh sieve.

[0060] The mixture in step S3 with added water and stirred should have a consistency of 90–110 mm before use.

[0061] S4. When using, apply evenly to areas with defects or scratches less than 5mm deep. The prepared paste must be used within 3 hours.

[0062] Unless otherwise specified, all parts mentioned in the embodiments of this invention refer to parts by weight.

[0063] The sand used in the embodiments of this invention has a specific surface area of ​​200-300 m². 2 / kg; color is white or off-white.

[0064] Example 1

[0065] This embodiment discloses the preparation method of the aerated concrete repair agent based on low-carbon cementitious materials according to the present invention, specifically as follows:

[0066] Autoclaved aerated concrete (AAC) waste is crushed, ground, and sieved through a 60-mesh screen. The raw materials are then uniformly mixed in the following proportions: 20 parts AAC waste; 5 parts low-carbon cementitious material; 70 parts sand; 4.8 parts natural gypsum; 0.2 parts water-retaining agent; 0.01 parts water-reducing agent; and 0.05 parts wood fiber. During construction, water is added and the mixture is stirred until the consistency reaches 100 mm before use.

[0067] The detailed physical performance parameters of the ingredients are shown in Table 1 below.

[0068] Table 1 Physical properties of the repair agent in Example 1

[0069]

[0070]

[0071] The aerated concrete in this embodiment is made from low-carbon cementitious materials. The mineral composition of the low-carbon cementitious materials is f-CaO 42wt.%. 6 wt.% C2S 42 wt.%; CaSO4 8 wt.% C4AF 2 wt.%; specific surface area 300 μm 2 / kg.

[0072] Example 2

[0073] This embodiment discloses the preparation method of the aerated concrete repair agent based on low-carbon cementitious materials according to the present invention, specifically as follows:

[0074] Autoclaved aerated concrete (AAC) waste is crushed, ground, and sieved through a 60-mesh screen. The raw materials are then uniformly mixed in the following proportions: 30 parts AAC waste; 5 parts low-carbon cementitious material; 55 parts sand; 9.6 parts anhydrite; 0.4 parts water-retaining agent; 0.01 parts water-reducing agent; and 0.05 parts wood fiber. During construction, water is added and the mixture is stirred until the consistency reaches 100 mm.

[0075] The detailed physical performance parameters of the ingredients are shown in Table 2 below.

[0076] Table 2 Physical properties of the repair agent in Example 2

[0077]

[0078] The aerated concrete in this embodiment is made from low-carbon cementitious materials. The mineral composition of the low-carbon cementitious materials is f-CaO 42wt.%. 6 wt.% C2S 42 wt.%; CaSO4 8 wt.% C4AF 2 wt.%; specific surface area 300 μm 2 / kg.

[0079] Example 3

[0080] This embodiment discloses the preparation method of the aerated concrete repair agent based on low-carbon cementitious materials according to the present invention, specifically as follows:

[0081] Autoclaved aerated concrete (AAC) waste is crushed, ground, and sieved through a 60-mesh screen. The raw materials are then uniformly mixed in the following proportions: 20 parts AAC waste; 10 parts low-carbon cementitious material; 65 parts sand; 4.5 parts phosphogypsum; 0.5 parts water-retaining agent; 0.01 parts water-reducing agent; and 0.05 parts wood fiber. During construction, water is added and the mixture is stirred until the consistency reaches 100 mm.

[0082] The detailed physical performance parameters of the ingredients are shown in Table 3 below.

[0083] Table 3 Physical properties of the repair agent in Example 3

[0084]

[0085] The aerated concrete in this embodiment is made from low-carbon cementitious materials. The mineral composition of the low-carbon cementitious materials is f-CaO 42wt.%. 6 wt.% C2S 42 wt.%; CaSO4 8 wt.% C4AF 2 wt.%; specific surface area 300 μm 2 / kg.

[0086] Example 4

[0087] This embodiment discloses the preparation method of the aerated concrete repair agent based on low-carbon cementitious materials according to the present invention, specifically as follows:

[0088] Autoclaved aerated concrete (AAC) waste is crushed, ground, and sieved through a 60-mesh screen. The raw materials are then uniformly mixed in the following proportions: 25 parts AAC waste; 10 parts low-carbon cementitious material; 65 parts sand; 4.7 parts natural gypsum; 0.3 parts water-retaining agent; 0.02 parts water-reducing agent; and 0.01 parts wood fiber. During construction, water is added and the mixture is stirred until the consistency reaches 100 mm before use.

[0089] The detailed physical performance parameters of the ingredients are shown in Table 4 below.

[0090] Table 4 Physical properties of the repair agent in Example 4

[0091]

[0092] The aerated concrete in this embodiment is made from low-carbon cementitious materials. The mineral composition of the low-carbon cementitious materials is f-CaO 42wt.%. 6 wt.% C2S 42 wt.%; CaSO4 8 wt.% C4AF 2 wt.%; specific surface area 300 μm 2 / kg.

[0093] As can be seen from the above embodiments, the aerated concrete repair agent of the present invention has a fast setting time, high tensile bond strength, high compressive strength, low shrinkage rate, and excellent performance.

[0094] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. An aerated concrete repair agent based on low-carbon cementitious materials, characterized in that, Including the following parts by weight of raw materials: Aerated concrete waste: 20-30 parts Low-carbon cementitious material: 5-10 parts Plaster: 5-10 parts Sand: 50-70 parts Water-retaining agent: 0.2~0.7 parts, Water-reducing agent: 0.01~0.02 parts, Fiber: 0.01~0.5 parts; The low-carbon cementitious material has a mineral composition of f-CaO 30~45wt.% and C4A3. 4~8 wt.%, C2S 40~50 wt.%, CaSO4 5~9 wt.%, C4AF 2~5 wt.%, specific surface area 300~400 m² 2 / kg.

2. The aerated concrete repair agent based on low-carbon cementitious materials according to claim 1, characterized in that, The waste material of aerated concrete is a dry powder mixture of powders from the cutting of blanks, damaged products, or products with unqualified shapes during the production process of aerated concrete.

3. The aerated concrete repair agent based on low-carbon cementitious materials according to claim 1, characterized in that, The sand includes at least one of natural quartz sand, dolomite sand, and natural river sand, with a chemical composition of SiO2 ≥ 80% and a specific surface area of ​​200~300 m². 2 / kg; the sand is white or off-white in color.

4. The aerated concrete repair agent based on low-carbon cementitious materials according to claim 1, characterized in that, The gypsum is selected from any one or more of natural gypsum, anhydrite, and phosphogypsum; Or / and the water-reducing agent is selected from polycarboxylate superplasticizers; Or / and the water-retaining agent is selected from one or two of methyl cellulose ether, hydroxypropyl methylcellulose, polyacrylamide, and hydroxyethyl methyl cellulose ether; The fibers may be selected from one or two of polypropylene fibers, polyester fibers, and wood fibers.

5. A method for preparing an aerated concrete repair agent based on low-carbon cementitious materials according to any one of claims 1-4, characterized in that, Includes the following steps: S1. Weigh out each raw material according to the proportions; S2. Release all raw materials from the storage tank and mix them thoroughly; S3. When ready to use, add water and stir.

6. The preparation method according to claim 5, characterized in that, The aerated concrete waste is crushed, ground, and screened before being used.

7. The preparation method according to claim 6, characterized in that, The sieving process involves passing through a 60-mesh sieve.

8. The preparation method according to claim 5, characterized in that, The mixture in step S3 with added water and stirred should have a consistency of 90-110 mm before use.

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