Foam concrete with good durability and preparation method thereof

Abstract

The invention relates to the technical field of concrete preparation, and particularly discloses foam concrete with good durability and a preparation method thereof. The invention discloses foam concrete with good durability. The foam concrete is prepared from the following raw materials in parts by mass: 90 to 120 parts of cement, 40 to 60 parts of fly ash, 30 to 55 parts of regenerated rubber powder, 2.7 to 3.5 parts of fiber, 2 to 4 parts of sodium carboxymethyl starch, 0.2 to 0.4 part of inulin, 0.7 to 1 part of foaming agent, 0.43 to 0.92 part of water reducing agent and 63 to 86 parts of water. The foam concrete provided by the invention has good mechanical properties, working performance and durability.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete preparation, and in particular to a foamed concrete with good durability and a preparation method thereof. Background Art

[0002] Foamed concrete is a lightweight and porous cement-based material, which is prepared by uniformly distributing a large number of stable micro-bubbles in cement paste or mortar. It combines the strength and stability of traditional concrete with the light weight and heat insulation characteristics of foam materials, and has multiple functions such as heat insulation, weight reduction of the structure, earthquake resistance and sound insulation. Therefore, it is widely used in many fields such as building insulation, sound insulation walls, floor heating filling layers, roof slope finding, and bridge fillers.

[0003] However, the bubbles in the existing foamed concrete are prone to rupture or coalescence, resulting in uneven pore size distribution and the formation of more connected pores, which may reduce the chemical stability of the foamed concrete. When in contact with the external environment, especially when exposed to corrosive media such as acid rain and salt spray, these corrosive media are more likely to invade the interior of the foamed concrete through the connected pores, accelerating its erosion and aging process. In addition, the presence of a large amount of foam may also interfere with the normal hydration process of the foamed concrete, resulting in an insufficiently dense microstructure of the formed colloidal skeleton and further decline in durability. Therefore, it is particularly necessary to improve the durability of foamed concrete to meet its application requirements in various complex environments. Summary of the Invention

[0004] In order to improve the durability of foamed concrete, the present application provides a foamed concrete with good durability and a preparation method thereof.

[0005] In a first aspect, a foamed concrete with good durability provided by the present application adopts the following technical solution: A foamed concrete with good durability, comprising the following raw materials in parts by mass: 90-120 parts of cement, 40-60 parts of fly ash, 30-55 parts of recycled rubber powder, 2.7-3.5 parts of fiber, 2-4 parts of sodium carboxymethyl starch, 0.2-0.4 parts of inulin, 0.7-1 part of foaming agent, 0.43-0.92 part of water reducing agent, and 63-86 parts of water.

[0006] In the above technical solution, the present application significantly improves the durability of foamed concrete through a specific raw material ratio. By using cement and fly ash as the main raw materials, it not only endows the foamed concrete with sufficient strength, but also forms a more compact microstructure through chemical reactions between the raw materials, effectively reducing the generation of connected pores. By further adding recycled rubber powder, the toughness and crack resistance of the foamed concrete are further enhanced. Through the use of sodium carboxymethyl starch and inulin, their interaction promotes the stable and uniform distribution of bubbles, thereby improving the stability of the foam system. This enables the foamed concrete to have a better porosity and pore size distribution, significantly reducing the number of coherent pores. Combined with the use of recycled rubber powder, the hydration process of the foamed concrete is slowed down, and the secondary hydration of the foamed concrete is promoted, ultimately forming a more compact microstructure, effectively improving the durability and mechanical properties of the concrete. By introducing fibers, the tensile strength of the foamed concrete is further enhanced, effectively preventing the generation and expansion of cracks. At the same time, the present application ensures that the foamed concrete has good foaming effect and workability by adding a foaming agent and a water reducer.

[0007] Preferably, it includes the following raw materials in parts by mass: 100 parts of cement, 50 parts of fly ash, 45 parts of recycled rubber powder, 3.1 parts of fiber, 2.9 parts of sodium carboxymethyl starch, 0.3 part of inulin, 0.9 part of foaming agent, 0.76 part of water reducer, and 78 parts of water.

[0008] In the above technical solution, the present application further improves the durability of foamed concrete by further optimizing the raw material ratio. Among them, cement and fly ash are used as the main raw materials, and their dosages can not only ensure the strength of the foamed concrete, but also form a compact microstructure through chemical reactions. The addition amount of recycled rubber powder can not only enhance the toughness and crack resistance of the foamed concrete, but also not overly slow down the hydration process. The interaction between sodium carboxymethyl starch, inulin and recycled rubber powder further promotes the stable and uniform distribution of bubbles, improving the stability of the foam system. The addition amount of fibers is also just right, which not only enhances the tensile strength of the foamed concrete, but also effectively prevents the generation and expansion of cracks. The addition amounts of the foaming agent and the water reducer also ensure that the foamed concrete has good foaming effect and workability.

[0009] Preferably, the foaming agent is a mixture of sodium dodecyl sulfate, betaine and nano-aluminum oxide in a mass ratio of 1:(0.5 - 0.7):(0.2 - 0.4).

[0010] In the above technical solution, the present application uses sodium dodecyl sulfate, betaine, and nano-aluminum oxide mixed in a specific ratio as a foaming agent. The three interact with each other to form a more stable foam interface, making the foam less likely to merge or break, and ensuring the uniform distribution of the pore structure in the foam concrete. At the same time, in the research of the present application, it is found that sodium dodecyl sulfate, betaine, and nano-aluminum oxide can also jointly regulate the fluidity of the foam concrete slurry, delay the early hydration process, and promote the secondary hydration reaction in the later stage. Finally, it further improves the density of the colloidal skeleton of the foam concrete, reduces micro-defects, and thus further enhances the mechanical properties and durability of the foam concrete.

[0011] Preferably, the foaming agent is a mixture of sodium dodecyl sulfate, betaine, and nano-aluminum oxide in a mass ratio of 1:0.6:0.3.

[0012] In the above technical solution, by further optimizing the ratio of sodium dodecyl sulfate, betaine, and nano-aluminum oxide, the interaction between the three is more coordinated. It can not only form a more stable foam interface, but also better regulate the fluidity of the foam concrete slurry, further delay the early hydration process, and promote the secondary hydration reaction in the later stage, so that the foam concrete has better mechanical properties and durability.

[0013] Preferably, the fiber is one or a combination of polypropylene fiber, polyester fiber, or glass fiber.

[0014] In the above technical solution, polypropylene fiber, polyester fiber, and glass fiber all have high strength and toughness, which can effectively enhance the tensile strength of the foam concrete and prevent the generation and expansion of cracks. At the same time, these fibers can also form good combinations with other components in the foam concrete, improving the overall performance of the foam concrete.

[0015] Preferably, the fiber is glass fiber.

[0016] In the above technical solution, due to its high strength and good corrosion resistance, the addition of glass fiber not only significantly improves the tensile strength and crack resistance of the foam concrete, but also makes the foam concrete have better durability in harsh environments.

[0017] Preferably, the water reducer is a polycarboxylate-based high-performance water reducer.

[0018] In the above technical solution, the polycarboxylate-based high-performance water reducer has excellent water-reducing effect and dispersion performance, which can effectively reduce the water-cement ratio of the foam concrete and improve the strength and durability of the concrete. At the same time, the polycarboxylate-based high-performance water reducer can also interact with other components in the foam concrete to further improve the workability and mechanical properties of the concrete.

[0019] In a second aspect, a method for preparing foamed concrete with good durability provided by the present application adopts the following technical solution: A method for preparing foamed concrete with good durability includes the following steps: Step 1: Dry-mix and uniformly mix cement, fly ash, recycled rubber powder, fibers, sodium carboxymethyl starch, and inulin; Step 2: Mix and stir evenly a water reducer and 35% - 40% of the formulated amount of water, add it to the material obtained in Step 1, and continue to stir evenly; Step 3: Add the remaining water and a foaming agent to a foaming machine, and stir until foam is obtained; Step 4: Add the material obtained in Step 3 to the material obtained in Step 2, and stir until evenly mixed to obtain a foamed concrete slurry; Step 5: After pouring, demolding, and curing the foamed concrete slurry obtained in Step 4, foamed concrete with good durability is obtained.

[0020] In the above technical solution, through the above preparation method, by performing steps such as dry-mixing, wet-mixing, foaming, and mixing on each raw material according to a certain ratio, foamed concrete with good durability can be obtained. Such a preparation method is not only applicable to large-scale production but also to small-scale laboratory preparation, and has a wide range of application prospects.

[0021] In summary, the present application includes at least one of the following beneficial technical effects: 1. By adding recycled rubber powder, the present application not only enhances the toughness and crack resistance of foamed concrete but also promotes the secondary hydration of foamed concrete, further improving its durability. The interaction between sodium carboxymethyl starch and inulin promotes the stable and uniform distribution of bubbles, improves the stability of the foam system, enables foamed concrete to have a better porosity and pore size distribution, and further interacts with recycled rubber powder to delay the early hydration process and promote the secondary hydration reaction in the later stage, further optimizing the compactness of the colloidal skeleton of foamed concrete.

[0022] 2. By mixing sodium dodecyl sulfate, betaine, and nano-aluminum oxide in a specific ratio as a foaming agent, the three interact with each other to form a more stable foam interface, jointly regulate the fluidity of the foamed concrete slurry, delay the early hydration process, and promote the secondary hydration reaction in the later stage, thereby further enhancing the mechanical properties and durability of foamed concrete. Specific Embodiments

[0023] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0024] Example 1 A foam concrete with good durability, comprising the following raw materials: 90 kg of cement, 40 kg of fly ash, 30 kg of recycled rubber powder, 2.7 kg of fiber, 2 kg of sodium carboxymethyl starch, 0.2 kg of inulin, 0.7 kg of foaming agent, 0.43 kg of water reducing agent, and 63 kg of water.

[0025] Among them, the foaming agent is a mixture of sodium dodecyl sulfate, betaine and nano-aluminum oxide in a mass ratio of 1:0.5:0.4.

[0026] Among them, the fiber is glass fiber.

[0027] Among them, the water reducing agent is a polycarboxylate-based high-performance water reducing agent.

[0028] Among them, the cement is Nanchang Conch brand P.O.42.5 ordinary portland cement.

[0029] Among them, the fly ash is secondary fly ash.

[0030] Among them, the recycled rubber powder is purchased from Jinan Baijin Chemical Technology Co., Ltd., specification: 80 mesh.

[0031] Among them, the glass fiber is purchased from Shijiazhuang Borui Building Materials Co., Ltd., specification: 300 mesh.

[0032] Among them, the sodium carboxymethyl starch is purchased from Nanjing Tongying Biotechnology Co., Ltd.

[0033] Among them, the inulin is purchased from Jiangsu Baiyao Biotechnology Co., Ltd.

[0034] Among them, the sodium dodecyl sulfate is purchased from Langfang Qianyao Technology Co., Ltd.

[0035] Among them, the betaine is purchased from Xi'an Musen Bioengineering Co., Ltd.

[0036] Among them, the nano-aluminum oxide is purchased from Yixing Haiyu Refractory Materials Co., Ltd.

[0037] Among them, the polycarboxylate-based high-performance water reducing agent is purchased from Wuhan Huaxuan High-Tech Co., Ltd.

[0038] Among them, the preparation method of the foam concrete with good durability includes the following steps: Step 1: Dry mix and mix evenly the cement, fly ash, recycled rubber powder, fiber, sodium carboxymethyl starch, and inulin.

[0039] Step 2: Mix and stir evenly the water reducing agent and 40% of the formula amount of water, add it to the material obtained in Step 1, and continue to stir evenly.

[0040] Step 3: Add the remaining water and the foaming agent to the foaming machine and stir until foam is obtained.

[0041] Step 4: Add the material obtained in Step 3 to the material obtained in Step 2, and stir until evenly mixed to obtain a foamed concrete slurry.

[0042] Step 5: After pouring, demolding and curing the foamed concrete slurry obtained in Step 4, foamed concrete with good durability is obtained.

[0043] Example 2 A kind of foamed concrete with good durability, different from Example 1, includes the following raw materials: 100 kg of cement, 50 kg of fly ash, 45 kg of recycled rubber powder, 3.1 kg of fiber, 2.9 kg of sodium carboxymethyl starch, 0.3 kg of inulin, 0.9 kg of foaming agent, 0.76 kg of water reducing agent, 78 kg of water.

[0044] Among them, the foaming agent is composed of sodium dodecyl sulfate, betaine and nano-aluminum oxide mixed in a mass ratio of 1:0.6:0.3.

[0045] Among them, the preparation method of the foamed concrete with good durability includes the following steps: Step 1: Dry mix and evenly mix cement, fly ash, recycled rubber powder, fiber, sodium carboxymethyl starch and inulin.

[0046] Step 2: Mix the water reducing agent and 40% of the formulated amount of water and stir evenly, add it to the material obtained in Step 1, and continue to stir evenly.

[0047] Step 3: Add the remaining water and the foaming agent to the foaming machine, and stir until foam is obtained.

[0048] Step 4: Add the material obtained in Step 3 to the material obtained in Step 2, and stir until evenly mixed to obtain a foamed concrete slurry.

[0049] Step 5: After pouring, demolding and curing the foamed concrete slurry obtained in Step 4, foamed concrete with good durability is obtained.

[0050] Example 3 A kind of foamed concrete with good durability, different from Example 1, includes the following raw materials: 120 kg of cement, 60 kg of fly ash, 55 kg of recycled rubber powder, 3.5 kg of fiber, 4 kg of sodium carboxymethyl starch, 0.4 kg of inulin, 1 kg of foaming agent, 0.92 kg of water reducing agent, 86 kg of water.

[0051] Among them, the foaming agent is composed of sodium dodecyl sulfate, betaine and nano-aluminum oxide mixed in a mass ratio of 1:0.7:0.2.

[0052] Among them, the preparation method of the foamed concrete with good durability includes the following steps: Step 1: Dry-mix and mix evenly cement, fly ash, recycled rubber powder, fibers, sodium carboxymethyl starch, and inulin.

[0053] Step 2: Mix the water reducer and 35% of the formulated amount of water and stir evenly, add it to the material obtained in Step 1, and continue to stir evenly.

[0054] Step 3: Add the remaining water and the foaming agent to the foaming machine and stir until foam is obtained.

[0055] Step 4: Add the material obtained in Step 3 to the material obtained in Step 2 and stir until evenly mixed to obtain foamed concrete slurry.

[0056] Step 5: After pouring, demolding, and curing the foamed concrete slurry obtained in Step 4, foamed concrete with good durability is obtained.

[0057] Example 4 A kind of foamed concrete with good durability, different from Example 1, sodium dodecyl sulfate in the foaming agent is replaced with an equal amount of sodium dodecyl benzene sulfonate.

[0058] Example 5 A kind of foamed concrete with good durability, different from Example 1, betaine in the foaming agent is replaced with an equal amount of triethanolamine.

[0059] Example 6 A kind of foamed concrete with good durability, different from Example 1, nano-aluminum oxide in the foaming agent is replaced with an equal amount of nano-silica.

[0060] Comparative Example 1 A kind of foamed concrete, different from Example 1, sodium carboxymethyl starch is replaced with an equal amount of hydroxypropyl methyl cellulose.

[0061] Comparative Example 2 A kind of foamed concrete, different from Example 1, inulin is replaced with an equal amount of maltodextrin.

[0062] Performance testing Flow value (mm) testing: Test the flow value of the foamed concrete slurry of each of the above examples and comparative examples. Place a hollow cylinder vertically in the middle of a smooth glass plate, slowly pour the foamed concrete slurry into the cylinder, and gently tap the outside of the hollow cylinder with a flat knife to make the foamed concrete slurry fill the entire hollow cylinder. Slowly scrape the sample flat along the port plane of the hollow cylinder with a flat knife, then slowly lift the cylinder upward to make the foamed concrete slurry naturally collapse and stand for 1 min, and then measure its maximum horizontal diameter with a vernier caliper, accurate to 1 mm. Repeat the above steps 3 times, and take the average value as the flow value of the foamed concrete slurry.

[0063] Compressive strength (MPa): The compressive strength of the foamed concrete in each of the above-mentioned examples and comparative examples after 28 days of curing was determined with reference to the test method in "Foamed Concrete" (JG / T 266-2011).

[0064] Dry density (kg / m 3 ): The dry density of the foamed concrete in each of the above-mentioned examples and comparative examples after 28 days of curing was determined with reference to the test method in "Foamed Concrete" (JG / T 266-2011).

[0065] Water absorption rate (%): The water absorption rate of the foamed concrete in each of the above-mentioned examples and comparative examples after 28 days of curing was determined with reference to the test method in "Foamed Concrete" (JG / T 266-2011).

[0066] Mass loss rate of freeze-thaw cycles (%): The mass loss rate of freeze-thaw cycles of the foamed concrete in each of the above-mentioned examples and comparative examples after 28 days of curing was determined with reference to the test method in "Test Methods for Properties of Foamed Concrete Products" (JC / T 2357-2016). The freeze-thaw conditions were: freezing in a low-temperature chamber at (-20±2)°C for 6 h, then taking out and putting into a constant-temperature water tank with water temperature (20±5)°C to melt for 5 h as one cycle, and a total of 35 cycles were carried out.

[0067] Mass loss rate of dry-wet cycles (%): The mass loss rate of dry-wet cycles of the foamed concrete in each of the above-mentioned examples and comparative examples after 28 days of curing was determined with reference to the test method in "Test Methods for Properties of Autoclaved Aerated Concrete" (GB / T 11969-2020). The dry-wet cycle conditions were: putting into a constant-temperature water tank at (20±5)°C, with the water level 30 mm above the upper surface of the specimen, keeping for 5 minutes and then taking out, air-drying indoors for 30 minutes, then putting into an oven at (60±5)°C for constant-temperature drying for 7 h, and then taking out the specimen to cool for 20 min as one cycle, and a total of 25 cycles were carried out.

[0068] The above test results are shown in Table 1.

[0069] Table 1: According to the analysis of the test results of Examples 1-6, Comparative Examples 1-2 and Table 1, it can be seen that for the foamed concrete of Examples 1-6 of the present application, the flow value is maintained at a relatively high level, the compressive strength is good, the dry density and water absorption rate are good, and the mass loss rate of freeze-thaw cycles and the mass loss rate of dry-wet cycles are maintained at a relatively low level. Thus, it can be seen that the foamed concrete of the present application has good mechanical properties and durability.

[0070] Specifically, in combination with the analysis of the foamed concrete in Example 1 and Comparative Examples 1-2, different from Example 1, in Comparative Example 1, hydroxypropyl methylcellulose was replaced with sodium carboxymethyl starch, and in Comparative Example 2, maltodextrin was replaced with inulin. Example 1 has good flow value, compressive strength and durability of foamed concrete. Thus, it can be seen that the combined use of sodium carboxymethyl starch and inulin has a significant impact on the performance of foamed concrete, can further enhance the stability of the foam system, delay the early hydration process, provide more time and conditions for the later secondary hydration reaction, thereby optimizing the colloidal skeleton structure of foamed concrete and improving its durability and mechanical properties.

[0071] Specifically, in combination with the analysis of the foamed concrete in Example 1 and Examples 4-6, different from Example 1, in Example 4, sodium dodecyl sulfate in the foaming agent was replaced with an equal amount of sodium dodecylbenzenesulfonate, in Example 5, betaine in the foaming agent was replaced with an equal amount of triethanolamine, and in Example 6, nano-aluminum oxide in the foaming agent was replaced with an equal amount of nano-silica. Example 1 has good flow value, compressive strength and durability of foamed concrete. Thus, it can be seen that the combined use of sodium dodecyl sulfate, betaine and nano-aluminum oxide plays an important role in the performance of foamed concrete. The interaction among the three enables foamed concrete to have a better pore structure and mechanical properties.

[0072] This specific embodiment is only an interpretation of the present application and does not limit the present application. After reading this specification, those skilled in the art can make modifications to this embodiment without creative contributions as needed, but as long as it is within the scope of the claims of the present application, it is protected by the patent law.

Claims

1. A foamed concrete with good durability, characterized in that: The invention comprises the following raw materials in parts by weight: 90 to 120 parts of cement, 40 to 60 parts of fly ash, 30 to 55 parts of recycled rubber powder, 2.7 to 3.5 parts of fiber, 2 to 4 parts of sodium carboxymethyl starch, 0.2 to 0.4 parts of inulin, 0.7 to 1 parts of foaming agent, 0.43 to 0.92 parts of water reducing agent and 63 to 86 parts of water.

2. The foamed concrete with good durability according to claim 1, characterized in that: The invention comprises the following raw materials in parts by weight: 100 parts of cement, 50 parts of fly ash, 45 parts of recycled rubber powder, 3.1 parts of fiber, 2.9 parts of sodium carboxymethyl starch, 0.3 parts of inulin, 0.9 parts of foaming agent, 0.76 parts of water reducing agent and 78 parts of water.

3. The foamed concrete with good durability according to claim 1, characterized in that: The foaming agent is prepared by mixing sodium dodecyl sulfate, betaine and nano-alumina in a mass ratio of 1: (0.5-0.7): (0.2-0.4).

4. The foamed concrete with good durability according to claim 3, characterized in that: The foaming agent is prepared by mixing sodium dodecyl sulfate, betaine and nano-alumina in a mass ratio of 1:0.6:0.

3.

5. The foamed concrete with good durability according to claim 1, characterized in that: The fiber is one or more combinations of polypropylene fiber, polyester fiber or glass fiber.

6. The foamed concrete with good durability according to claim 5, characterized in that: The fibers are glass fibers.

7. The foamed concrete with good durability according to claim 1, characterized in that: The water reducing agent is a polycarboxylic acid-based high-performance water reducing agent.

8. A method for preparing foamed concrete with good durability, characterized in that: The following steps are involved: Step 1: dry mix cement, fly ash, recycled rubber powder, fiber, sodium carboxymethyl starch and inulin and mix them evenly; Step 2: Mix the water reducer and 35% to 40% of the formula amount of water and stir evenly, add it to the material obtained in step 1, and continue to stir evenly; Step 3: Add the remaining water and foaming agent into the foaming machine and stir until foam is obtained; Step 4: Add the material obtained in step 3 to the material obtained in step 2, and stir until the mixture is uniform to obtain foamed concrete slurry; Step 5: After pouring, demolding and curing the foamed concrete slurry obtained in step 4, foamed concrete with good durability is obtained.

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