Foam concrete and preparation method thereof

Abstract

The invention relates to the field of environment-friendly building construction, and discloses foam concrete, which is prepared from 42 g of GO solution, 70 g of metakaolin, 630 g of cement, 2.31 g of polycarboxylate superplasticizer powder, 350 g of water and 3 g of foaming agent. The graphene oxide and the metakaolin can generate an adsorption effect in the cement, and the connection between graphene oxide groups which should be agglomerated originally is broken by utilizing the flaky form of the metakaolin, so that the dispersity of the graphene oxide is improved, and the advantage that the graphene oxide enhances the strength of the foam concrete is exerted; the thermal insulation performance of the foam concrete is also enhanced, and meanwhile, the metakaolin also has the effect of improving the strength of the foam concrete.

Description

Technical Field

[0001] This invention relates to the field of environmentally friendly building construction, specifically to a foamed concrete and its preparation method. Background Technology

[0002] Concrete that combines energy conservation, environmental protection, lightweight, and high strength is a future global development trend, and foamed concrete is a material possessing these functions. Currently, many developed countries have well-established applications, such as backfilling, roof insulation, underfloor heating insulation, and explosion-proof walls. With the encouragement of the development and application of lightweight, high-strength concrete, many researchers have conducted extensive research in this area. However, production capacity cannot keep pace with the development of new materials, hindering the development of foamed concrete. While graphene oxide is often added as an admixture to foamed concrete, graphene oxide tends to agglomerate in cement. This agglomeration limits its ability to enhance concrete strength, especially in foamed concrete. Agglomerated graphene oxide clusters increase the thermal conductivity of the foamed concrete, leading to insufficient compressive strength. Therefore, we propose a foamed concrete method and its preparation. Summary of the Invention

[0003] (a) Technical problems to be solved

[0004] To address the shortcomings of existing technologies, this invention provides a foamed concrete and its preparation method, which solves the problem of insufficient compressive strength in graphene foamed concrete.

[0005] (II) Technical Solution

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution: a foamed concrete, comprising GO solution, metakaolin, cement, polycarboxylate superplasticizer powder, water, and a foaming agent, wherein the proportions are as follows: 42g GO solution, 70g metakaolin, 630g cement, 2.31g polycarboxylate superplasticizer powder, 350g water, and 3g foaming agent.

[0007] A method for preparing foamed concrete includes the following steps:

[0008] Step 1: Determine the water-to-binder ratio and calculate the total amount of water required. Then divide the water into two parts: 2 / 3 and 1 / 3.

[0009] Step 2: Add cement and metakaolin to the foamed concrete mixing bucket, mix, then add 2 / 3 of the water, mix again to obtain cement slurry;

[0010] Step 3: Foam the foaming agent and spray it evenly onto the cement slurry;

[0011] Step 4: Add the GO solution and polycarboxylate superplasticizer powder to the remaining 1 / 3 of the water, stir to obtain GO-PCE dispersion, and evenly pour it onto the foam;

[0012] Step 5: Mix again, pour into molds, and obtain foamed concrete.

[0013] Preferably, the stirring conditions in the second step are stirring at a speed of 100 r / min for 1 minute.

[0014] Preferably, the foaming conditions in the third step are to mix the foaming agent and water, stir them evenly, and then foam them using a foaming machine.

[0015] Preferably, the stirring conditions in the fourth step are: stirring for 1 minute at a speed of 1000 r / min using a top-mounted electric stirrer.

[0016] Preferably, the stirring conditions in the fifth step are stirring at a speed of 100 r / min for 3 minutes.

[0017] (III) Beneficial Effects

[0018] Compared with the prior art, the present invention provides a foamed concrete and its preparation method, which has the following beneficial effects:

[0019] 1. The foamed concrete and its preparation method utilize metakaolin, which has high activity and can react with cement hydration products to form a microstructure similar to calcium silicate hydrate, thereby improving the density and overall strength of the concrete.

[0020] 2. The foamed concrete and its preparation method: The size of graphene oxide is usually 1-10 nm, while the size of cement is about 10,000 nm. Adding metakaolin with a size of 1,000 nm can fill the micropores in the graphene oxide foamed concrete, improve the density of the foamed concrete, form a more compact skeleton structure, and thus improve the compressive strength.

[0021] 3. The foamed concrete and its preparation method demonstrate the synergistic effect of the composite of metakaolin and graphene oxide. The excellent mechanical properties of graphene oxide and the contribution of metakaolin can jointly enhance the compressive strength of the concrete, resulting in a significant performance improvement compared to using only one material.

[0022] 4. The foamed concrete and its preparation method, metakaolin can improve the adhesion between the components in the concrete, and this improved adhesion helps to enhance the overall mechanical properties of the concrete.

[0023] 5. This foamed concrete and its preparation method utilize metakaolin, which reduces the drying shrinkage of the concrete and minimizes microcracks caused by shrinkage. This better maintains the structural integrity of the concrete, thereby enhancing its compressive strength. The final demolded and cured specimens are shown below. Figure 2 As shown, the specimens had no missing edges or corners, the surface flatness was less than 3 mm, the dimensional deviation was less than 1 mm, and the surface was free of oil stains, cracks, and looseness as measured by visual inspection, which met the standard of "Foamed Concrete" (JG / T266-2011). Attached Figure Description

[0024] Figure 1 A schematic diagram of the GM specimen molding process;

[0025] Figure 2 This is a schematic diagram of the curing process for GM specimens. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Please see Figure 1-2 A method for preparing foamed concrete, comprising the following:

[0028] Step 1: Determine the water-to-binder ratio. After calculating the total water required, divide the remaining water (after deducting the water for the graphene oxide solution) into two parts: 2 / 3 and 1 / 3. Add these two parts to the material in batches and stir. The first part is 2 / 3 of the water, and the second part is 1 / 3.

[0029] Step 2: Add 630g of dry cement and 70g of metakaolin to the foamed concrete mixing bucket, stir at 100r / min for 1 minute, then add 2 / 3 of the water, stir at 100r / min for another minute, and scrape the cement slurry off the bottom of the bucket and the mixing blades.

[0030] Step 3: Mix 3g of foaming agent and 15g of water, stir well, foam it with a foaming machine, and spray it evenly onto the cement slurry.

[0031] Step 4: Add 42g of GO solution and 2.31g of polycarboxylate superplasticizer powder to the remaining 1 / 3 of the water. Stir with a top-mounted electric stirrer at 1000r / min for 1 minute to obtain GO-PCE dispersion, and then evenly pour it onto the foam.

[0032] Step 5: Stir the foamed concrete in the mixing bucket at 100 r / min for 3 minutes, then pour it into the mold.

[0033] Note: The total water consumption includes the water content in the SE3122 graphene oxide solution with a solid content of 1%. This invention can prepare 10L of solution with a dry density not exceeding 600 kg / m³ in a single step. 3 Graphene oxide-metakaolin modified foamed concrete.

[0034] Based on the above, the following experimental example was conducted: the dry density and 28-day compressive strength were tested according to the method in "7.3 Performance Test" of "Foamed Concrete" (JG / T266-2011).

[0035] Using the method of this invention, the same dry density of 575 kg / m³ was produced. 3 The compressive strength of graphene oxide foamed concrete (Ref) and graphene oxide-metakaolin modified foamed concrete (GM) specimens were compared as shown in Table 1. Table 2 shows the comparison of their 28-day compressive strength.

[0036] Table 1 Mix proportions of foamed concrete

[0037] Specimen Name GO solution (g) Metakaolin (g) Cement (g) PCE(g) Water consumption (g) Foaming agent (g) Ref 42 0 700 1.26 350 3 GM 42 70 630 2.31 350 3

[0038] Table 2 Comparison of the effects on compressive strength

[0039]

[0040] Based on Table 2, comparing the compressive strength of the two at 28 days, it is clear that the compressive strength of the graphene oxide-metakaolin modified foamed concrete specimen (GM) proposed in this scheme is much higher than that of the graphene oxide foamed concrete (Ref).

[0041] Based on the above experiments: The graphene oxide used in this invention is a 1% solid content SE3122 graphene oxide solution produced by Changzhou Sixth Element Co., Ltd. The metakaolin is K-1300W high-activity metakaolin produced by Inner Mongolia Chaopai New Materials Co., Ltd. The cement is China Resources PO·42.5 type cement. The foaming agent is a concentrated high-efficiency cement foaming agent produced by Tianquan Commerce & Chemical Co., Ltd., with a foaming ratio of 10 times. The polycarboxylate superplasticizer is 540P high-performance superplasticizer from Shanghai Chenqi Chemical Technology Co., Ltd. All the above materials are commercially available, ensuring widespread applicability.

[0042] Graphene oxide (GO) is a hydrophilic nanomaterial. Its excellent isotropy allows it to promote cement hydration and improve concrete strength when uniformly distributed, making it an environmentally friendly material. However, a drawback is its tendency to agglomerate in cement, which limits its ability to enhance concrete strength. This is especially true in foamed concrete, where the agglomerated graphene clusters increase the thermal conductivity of the foamed concrete.

[0043] Metakaolin (MK) is anhydrous aluminum silicate (Al2O3·2SiO2) formed by dehydrating kaolin (Al2O3·2SiO2·2H2O) at a suitable temperature (600–900℃). Metakaolin is a highly active mineral admixture, an amorphous aluminum silicate formed from ultrafine kaolin through low-temperature calcination. It possesses high pozzolanic activity and is primarily used as a concrete admixture, and can also be used to produce high-performance geopolymers. Furthermore, the main components of metakaolin, Al2O3 and SiO2, react with Ca(OH)2 produced during cement hydration to form cement paste, which can improve the bonding strength of putty. From an economic perspective, metakaolin can replace some cement and latex powder, appropriately reducing costs.

[0044] Graphene oxide and metakaolinite adsorb each other in cement. The sheet-like morphology of metakaolinite breaks the bonds between the graphene oxide clusters that should be agglomerated, thereby improving the dispersibility of graphene oxide. This allows the advantages of graphene oxide in enhancing the strength of foamed concrete to be brought into play, and also enhances the thermal insulation performance of foamed concrete. At the same time, metakaolinite itself also has the effect of improving the strength of foamed concrete.

[0045] Using graphene oxide and metakaolin as admixtures, foamed concrete slurry with a dry density not exceeding 600 kg / m³ was prepared according to the steps described in "4.4 Preparation of Foamed Concrete Slurry" of the "Technical Specification for Application of Foamed Concrete" (JGJ_T341-2014). 3 Foamed concrete.

[0046] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A foamed concrete, characterized in that: It includes GO solution, metakaolin, cement, polycarboxylic acid high-efficiency water-reducing agent powder, water and foaming agent, and its proportion is as follows: 42g GO solution, 70g metakaolin, 630g cement, 2.31g polycarboxylic acid high-efficiency water-reducing agent powder, 350g water and 3g foaming agent.

2. A method for preparing foamed concrete, characterized in that: The following steps are involved: Step 1: Determine the water-binder ratio, calculate the total water consumption required, and divide the water consumption into two parts: 2 / 3 and 1 / 3; Step 2: Add cement and metakaolin into the foam concrete mixing barrel, add 2 / 3 of the water after stirring, and stir again to obtain cement slurry; Step 3: Foam the foaming agent and spray it evenly on the cement slurry; Step 4: Add GO solution and polycarboxylate superplasticizer powder to the remaining 1 / 3 of the water, stir to obtain GO-PCE dispersion, and evenly pour it on the foam; Step 5: Mix again and fill the mold to get foamed concrete.

3. The method for preparing foamed concrete according to claim 2, characterized in that: The stirring condition in the second step is stirring at a rotation speed of 100 r / min for 1 minute.

4. The method for preparing foamed concrete according to claim 2, characterized in that: The foaming conditions of the foaming agent in the third step are as follows: the foaming agent and water are mixed and stirred evenly, and then foamed by a foaming machine.

5. The method for preparing foamed concrete according to claim 2, characterized in that: The stirring condition in the fourth step is to use an overhead electric stirrer to stir at a speed of 1000 r / min for 1 minute.

6. The method for preparing foamed concrete according to claim 2, characterized in that: The stirring condition in the fifth step is stirring at a rotation speed of 100 r / min for 3 minutes.

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