Foamed lightweight concrete and preparation method thereof

Abstract

The invention relates to the field of building materials, in particular to foamed lightweight concrete and a preparation method thereof, and aims to solve the problem that existing foamed lightweight concrete is poor in mechanical strength and waterproof performance. According to the preparation method, the calcium carbonate whiskers are added into the raw materials, the calcium carbonate whiskers have good mechanical strength and stable chemical properties, after the calcium carbonate whiskers are added into the concrete, the toughening and reinforcing effects can be achieved, the mechanical properties of the concrete can be effectively improved, and then the dispersity and compatibility of all components of the concrete can be improved by adding the performance enhancer; by adding the performance enhancer, the hydrophobic and waterproof performance of the foamed lightweight concrete is greatly improved, the situation that the performance of the concrete is reduced due to water erosion is avoided, the high performance of the foamed lightweight concrete is kept for a long time, and the preparation method is simple and easy to implement, wide in raw material source, low in cost and suitable for industrial production. The method is suitable for industrial production.

Description

Technical Field

[0001] The invention relates to the field of building materials, and in particular to a foamed lightweight concrete and a preparation method thereof. Background Art

[0002] With the continuous development of the construction industry, the performance requirements for building materials are getting higher and higher. As a new type of building material, foamed lightweight concrete has the advantages of light weight, heat preservation, heat insulation, and sound insulation, and has been widely used in construction projects. However, the current foamed lightweight concrete still has certain deficiencies in mechanical strength and waterproof performance, especially in the long-term use process, it is easy to absorb water internally and the strength decreases, resulting in reduced durability of the building, which limits its application in some projects with higher performance requirements.

[0003] In view of the above technical defects, a solution is now proposed. Summary of the invention

[0004] In order to overcome the above technical problems, the object of the present invention is to provide a foamed lightweight concrete and a preparation method thereof: by uniformly mixing silicate cement, fine sand, fly ash, calcium carbonate whisker, sodium dodecylbenzene sulfonate, a water reducer, calcium stearate, a performance enhancer and water, then pouring into a mold, vibrating and compacting and then curing, and then demolding to obtain foamed lightweight concrete, which solves the problem that the existing foamed lightweight concrete has poor mechanical strength and waterproof performance, which limits its application in some projects with high performance requirements.

[0005] The purpose of the present invention can be achieved through the following technical solutions: A foamed lightweight concrete comprises the following components in parts by weight: 200-220 parts of Portland cement, 250-280 parts of fine sand, 100-120 parts of fly ash, 18-46 parts of calcium carbonate whiskers, 3-11 parts of sodium dodecylbenzene sulfonate, 1-3 parts of water reducer, 4-8 parts of calcium stearate, 1.3-7.7 parts of performance enhancer and 175-195 parts of water; Wherein, the performance enhancer is prepared by the following steps: Step a1: 3,3',4,4'-biphenyltetracarboxylic dianhydride, concentrated sulfuric acid and N,N-dimethylformamide are added to a three-necked flask equipped with a stirrer and a thermometer, and stirred for reaction for 20-30 minutes at a temperature of 25-30°C and a stirring rate of 200-300 r / min, and then the temperature is raised to 50-55°C and the stirring reaction is continued for 1-2 hours, and then N-bromosuccinimide is added and the temperature is raised to 90-100°C and the stirring reaction is continued for 10-15 hours. After the reaction is completed, the reaction product is cooled to room temperature, and then added to ice water, and allowed to stand to precipitate, and then vacuum filtered, and the filter cake is washed with distilled water 2-3 times to obtain intermediate 1; Step a2: Add intermediate 1, perfluorohexylethanol, anhydrous potassium carbonate and tetrahydrofuran into a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser, introduce nitrogen protection, stir and react for 20-30 minutes at a temperature of 25-30° C. and a stirring rate of 200-300 r / min, then heat to reflux and continue stirring and reacting for 5-6 hours. After the reaction is completed, the reaction product is cooled to room temperature, then vacuum filtered, and the filtrate is rotary evaporated to remove the solvent to obtain intermediate 2; Step a3: Add intermediate 2, ethanolamine and anhydrous ethanol to a three-necked flask equipped with a stirrer, a thermometer and an air guide tube, introduce nitrogen protection, stir the reaction at a temperature of 25-30° C. and a stirring rate of 200-300 r / min for 20-30 min, then heat to 80-85° C. and continue stirring the reaction for 8-10 h. After the reaction is completed, cool the reaction product to room temperature, then rotary evaporate to remove the solvent, and then place it in a vacuum drying oven and dry it at a temperature of 50-55° C. for 2-3 h to obtain intermediate 3; Step a4: Add intermediate 3, triethylamine and tetrahydrofuran to a three-necked flask equipped with a stirrer, a thermometer, an air duct and a reflux condenser, introduce nitrogen protection, stir and react for 20-30 minutes at a temperature of 25-30°C and a stirring rate of 200-300r / min, then add isocyanatepropyltriethoxysilane and continue stirring and reacting for 8-10 hours under the condition of raising the temperature to reflux. After the reaction, cool the reaction product to room temperature, then rotary evaporate to remove the solvent, then wash with petroleum ether 2-3 times, then place in a vacuum drying oven, and dry at a temperature of 70-75°C for 2-3 hours to obtain a performance enhancer.

[0006] As a further embodiment of the present invention: the usage ratio of the 3,3',4,4'-biphenyltetracarboxylic dianhydride, concentrated sulfuric acid, N,N-dimethylformamide and N-bromosuccinimide in step a1 is 10 mmol: 10-15 mL: 40-50 mL: 25-45 mmol.

[0007] As a further solution of the present invention: the mass fraction of the concentrated sulfuric acid in step a1 is 98%.

[0008] As a further scheme of the present invention: the usage ratio of the intermediate 1, perfluorohexylethanol, anhydrous potassium carbonate and tetrahydrofuran in step a2 is 10 mmol: 25-35 mmol: 40-50 mmol: 80-100 mL.

[0009] As a further solution of the present invention: the usage ratio of the intermediate 2, ethanolamine and anhydrous ethanol in step a3 is 10 mmol: 20 mmol: 80-100 mL.

[0010] As a further scheme of the present invention: the usage ratio of the intermediate 3, triethylamine, tetrahydrofuran and isocyanatepropyltriethoxysilane in step a4 is 10 mmol: 0.01-0.03 g: 100-120 mL: 22-25 mmol.

[0011] As a further solution of the present invention: a method for preparing foamed lightweight concrete comprises the following steps: Step 1: weigh 200-220 parts of Portland cement, 250-280 parts of fine sand, 100-120 parts of fly ash, 18-46 parts of calcium carbonate whiskers, 3-11 parts of sodium dodecylbenzene sulfonate, 1-3 parts of water reducer, 4-8 parts of calcium stearate, 1.3-7.7 parts of performance enhancer and 175-195 parts of water according to weight parts, and keep them in reserve; Step 2: Mix silicate cement, fine sand, fly ash, calcium carbonate whisker, sodium dodecylbenzene sulfonate, water reducer, calcium stearate, performance enhancer and water evenly, then pour into a mold, vibrate and compact, place at room temperature for curing for 48 hours, and then demold to obtain foamed lightweight concrete.

[0012] As a further solution of the present invention: the average length of the calcium carbonate whiskers is 0.05 mm, the average diameter is 1.2 μm, the average tensile strength is 4800 MPa, and the average elastic modulus is 560 MPa.

[0013] As a further solution of the present invention: the water reducer is a FDN type naphthalene-based water reducer.

[0014] Beneficial effects of the present invention: The invention discloses a foamed lightweight concrete and a preparation method thereof. The foamed lightweight concrete is prepared by uniformly mixing silicate cement, fine sand, fly ash, calcium carbonate whisker, sodium dodecylbenzene sulfonate, a water reducer, calcium stearate, a performance enhancer and water, then pouring the mixture into a mold, performing vibration compaction and curing, and then demoulding the mixture to obtain the foamed lightweight concrete. The preparation method adds calcium carbonate whisker into raw materials. The calcium carbonate whisker has good mechanical strength and stable chemical properties. After being added into concrete, the calcium carbonate whisker can have a toughening and strengthening effect on the concrete, and can effectively improve the mechanical properties of the concrete. Afterwards, the performance enhancer is added to improve the dispersibility and compatibility of various components of the concrete and improve its compactness, thereby preparing the foamed lightweight concrete with high strength and high durability. The addition of the performance enhancer can also greatly improve the hydrophobic and waterproof properties of the concrete, thereby preventing the concrete from being eroded by water and causing the performance to decrease, and allowing the concrete to maintain high performance for a long time. The preparation method is simple and easy to implement, has a wide source of raw materials, is low in cost, and is suitable for industrial production.

[0015] In the process of preparing foamed lightweight concrete, a performance enhancer is first prepared. First, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and N-bromosuccinimide are reacted. N-bromosuccinimide is used as a brominating agent to introduce a large number of bromine atoms on the benzene ring of 3,3',4,4'-biphenyltetracarboxylic acid dianhydride to obtain intermediate 1. Then, intermediate 1 and perfluorohexylethanol are reacted. The bromine atoms on intermediate 1 react with the hydroxyl groups on perfluorohexylethanol to introduce a large number of CF bonds to obtain intermediate 2. Then, intermediate 2 and ethanolamine are reacted. The anhydride group on intermediate 2 reacts with the amino group on ethanolamine to form an imide group, and a hydroxyl group is introduced at the same time to obtain intermediate 3. Then, intermediate 3 is prepared by using The intermediate 3 and isocyanatepropyltriethoxysilane react, and the hydroxyl group on the intermediate 3 reacts with the isocyanate group on the isocyanatepropyltriethoxysilane to introduce a large number of siloxane groups to obtain a performance enhancer; the large number of siloxane groups on the molecular structure of the performance enhancer can form a large number of silanols after hydrolysis, and are grafted to the particle surfaces of various components of the concrete, so that the compatibility between the various components is greatly improved, the uniformity is improved, the density is improved, and the various components are connected through chemical bonds to improve their bonding strength, and finally the prepared concrete has excellent mechanical properties, and the large number of introduced CF bonds give the concrete low surface energy, so that the hydrophobicity is greatly improved, and it is not easily eroded by water. DETAILED DESCRIPTION

[0016] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Example 1

[0017] This embodiment is a method for preparing foamed lightweight concrete, comprising the following steps: Step S1: 10 mmol 3,3',4,4'-biphenyltetracarboxylic dianhydride, 10 mL of 98% concentrated sulfuric acid and 40 mL N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred for reaction at 25°C and a stirring rate of 200 r / min for 20 min, then heated to 50°C and continued to stir for 1 h, then added 25 mmol N-bromosuccinimide and heated to 90°C and continued to stir for 10 h, after the reaction was completed, the reaction product was cooled to room temperature, then added to ice water, allowed to stand for precipitation, then vacuum filtered, and the filter cake was washed twice with distilled water to obtain intermediate 1; Step S2: 10 mmol of intermediate 1, 25 mmol of perfluorohexylethanol, 40 mmol of anhydrous potassium carbonate and 80 mL of tetrahydrofuran were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred for reaction at 25° C. and a stirring rate of 200 r / min for 20 min, and then the temperature was raised to reflux and the stirring reaction was continued for 5 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain intermediate 2; Step S3: 10 mmol of intermediate 2, 20 mmol of ethanolamine and 80 mL of anhydrous ethanol were added to a three-necked flask equipped with a stirrer, a thermometer and a gas guide tube, and nitrogen was introduced for protection. The mixture was stirred at 25° C. and a stirring rate of 200 r / min for 20 min, and then the mixture was heated to 80° C. and stirred for 8 h. After the reaction, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. The mixture was then placed in a vacuum drying oven and dried at 50° C. for 2 h to obtain intermediate 3; Step S4: 10 mmol of intermediate 3, 0.01 g of triethylamine and 100 mL of tetrahydrofuran were added to a three-necked flask equipped with a stirrer, a thermometer, a gas duct and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred for reaction at 25° C. and a stirring rate of 200 r / min for 20 min, and then 22 mmol of isocyanatepropyltriethoxysilane was added and the mixture was heated to reflux and continued to stir for reaction for 8 h. After the reaction, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation, and then the mixture was washed twice with petroleum ether, and then placed in a vacuum drying oven and dried at 70° C. for 2 h to obtain a performance enhancer; Step S5: weigh 200 parts of silicate cement, 250 parts of fine sand, 100 parts of fly ash, 18 parts of calcium carbonate whiskers, 3 parts of sodium dodecylbenzene sulfonate, 1 part of water reducer, 4 parts of calcium stearate, 1.3 parts of performance enhancer and 175 parts of water according to weight parts, and prepare them for backup; the average length of the calcium carbonate whiskers is 0.05 mm, the average diameter is 1.2 μm, the average tensile strength is 4800 MPa, and the average elastic modulus is 560 MPa; the water reducer is FDN type naphthalene water reducer; Step S6: Mix silicate cement, fine sand, fly ash, calcium carbonate whisker, sodium dodecylbenzene sulfonate, water reducer, calcium stearate, performance enhancer and water evenly, then pour into a mold, vibrate compact and place at room temperature for curing for 48 hours, then demold to obtain foamed lightweight concrete. Example 2

[0018] This embodiment is a method for preparing foamed lightweight concrete, comprising the following steps: Step S1: 10 mmol 3,3',4,4'-biphenyltetracarboxylic dianhydride, 12 mL of 98% concentrated sulfuric acid and 45 mL N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred for reaction at a temperature of 28°C and a stirring rate of 250 r / min for 25 min, then heated to 53°C and continued to stir for reaction for 1.5 h, then added 35 mmol N-bromosuccinimide and heated to 95°C and continued to stir for reaction for 12 h, after the reaction was completed, the reaction product was cooled to room temperature, then added to ice water, allowed to stand for precipitation, then vacuum filtered, and the filter cake was washed twice with distilled water to obtain intermediate 1; Step S2: 10 mmol of intermediate 1, 30 mmol of perfluorohexylethanol, 45 mmol of anhydrous potassium carbonate and 90 mL of tetrahydrofuran were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred for reaction at 28° C. and a stirring rate of 250 r / min for 25 min, and then the temperature was raised to reflux and the stirring reaction was continued for 5.5 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain intermediate 2; Step S3: 10 mmol of intermediate 2, 20 mmol of ethanolamine and 90 mL of anhydrous ethanol were added to a three-necked flask equipped with a stirrer, a thermometer and a gas guide tube, and nitrogen was introduced for protection. The mixture was stirred at 28° C. and a stirring rate of 250 r / min for 25 min, and then the mixture was heated to 82° C. and the stirring reaction was continued for 9 h. After the reaction was completed, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. The mixture was then placed in a vacuum drying oven and dried at 52° C. for 2.5 h to obtain intermediate 3; Step S4: 10 mmol of intermediate 3, 0.02 g of triethylamine and 110 mL of tetrahydrofuran were added to a three-necked flask equipped with a stirrer, a thermometer, a gas duct and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred for reaction at 28° C. and a stirring rate of 250 r / min for 25 min, and then 24 mmol of isocyanatepropyltriethoxysilane was added and the mixture was heated to reflux and continued to stir for reaction for 9 h. After the reaction, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation, and then the mixture was washed twice with petroleum ether, and then placed in a vacuum drying oven and dried at 72° C. for 2.5 h to obtain a performance enhancer; Step S5: weighing 210 parts of silicate cement, 265 parts of fine sand, 110 parts of fly ash, 32 parts of calcium carbonate whiskers, 7 parts of sodium dodecylbenzene sulfonate, 2 parts of water reducer, 6 parts of calcium stearate, 4.5 parts of performance enhancer and 185 parts of water according to weight parts for backup; the calcium carbonate whiskers have an average length of 0.05 mm, an average diameter of 1.2 μm, an average tensile strength of 4800 MPa, and an average elastic modulus of 560 MPa; the water reducer is a FDN type naphthalene water reducer; Step S6: Mix silicate cement, fine sand, fly ash, calcium carbonate whisker, sodium dodecylbenzene sulfonate, water reducer, calcium stearate, performance enhancer and water evenly, then pour into a mold, vibrate compact and place at room temperature for curing for 48 hours, then demold to obtain foamed lightweight concrete.

[0019] Embodiment 3: This embodiment is a method for preparing foamed lightweight concrete, comprising the following steps: Step S1: 10 mmol 3,3',4,4'-biphenyltetracarboxylic dianhydride, 15 mL of 98% concentrated sulfuric acid and 50 mL N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer and a thermometer, and stirred for reaction at a temperature of 30°C and a stirring rate of 300 r / min for 30 min, then heated to 55°C and continued to stir for reaction for 2 h, then added 45 mmol N-bromosuccinimide and heated to 100°C and continued to stir for reaction for 15 h, after the reaction was completed, the reaction product was cooled to room temperature, then added to ice water, allowed to stand for precipitation, then vacuum filtered, and the filter cake was washed 3 times with distilled water to obtain intermediate 1; Step S2: 10 mmol of intermediate 1, 35 mmol of perfluorohexylethanol, 50 mmol of anhydrous potassium carbonate and 100 mL of tetrahydrofuran were added to a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred for reaction at 30° C. and a stirring rate of 300 r / min for 30 min, and then the temperature was raised to reflux and the stirring reaction was continued for 6 h. After the reaction was completed, the reaction product was cooled to room temperature, and then vacuum filtered, and the filtrate was rotary evaporated to remove the solvent to obtain intermediate 2; Step S3: 10 mmol of intermediate 2, 20 mmol of ethanolamine and 100 mL of anhydrous ethanol were added to a three-necked flask equipped with a stirrer, a thermometer and a gas guide tube, and nitrogen was introduced for protection. The mixture was stirred at 30° C. and a stirring rate of 300 r / min for 30 min, and then the mixture was heated to 85° C. and the stirring reaction was continued for 10 h. After the reaction was completed, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. The mixture was then placed in a vacuum drying oven and dried at 55° C. for 3 h to obtain intermediate 3; Step S4: 10 mmol of intermediate 3, 0.03 g of triethylamine and 120 mL of tetrahydrofuran were added to a three-necked flask equipped with a stirrer, a thermometer, a gas duct and a reflux condenser, and nitrogen was introduced for protection. The mixture was stirred for reaction at 30° C. and a stirring rate of 300 r / min for 30 min, and then 25 mmol of isocyanatepropyltriethoxysilane was added and the mixture was heated to reflux and continued to stir for 10 h. After the reaction, the reaction product was cooled to room temperature, and then the solvent was removed by rotary evaporation. The mixture was then washed with petroleum ether for 3 times, and then placed in a vacuum drying oven and dried at 75° C. for 3 h to obtain a performance enhancer; Step S5: weighing 220 parts of silicate cement, 280 parts of fine sand, 120 parts of fly ash, 46 parts of calcium carbonate whiskers, 11 parts of sodium dodecylbenzene sulfonate, 3 parts of water reducer, 8 parts of calcium stearate, 7.7 parts of performance enhancer and 195 parts of water according to weight parts for backup; the average length of the calcium carbonate whiskers is 0.05 mm, the average diameter is 1.2 μm, the average tensile strength is 4800 MPa, and the average elastic modulus is 560 MPa; the water reducer is FDN type naphthalene water reducer; Step S6: Mix silicate cement, fine sand, fly ash, calcium carbonate whisker, sodium dodecylbenzene sulfonate, water reducer, calcium stearate, performance enhancer and water evenly, then pour into a mold, vibrate compact and place at room temperature for curing for 48 hours, then demold to obtain foamed lightweight concrete.

[0020] Comparative Example 1: This comparative example is a method for preparing a foamed lightweight concrete, comprising the following steps: Step S1: weigh 220 parts of Portland cement, 280 parts of fine sand, 120 parts of fly ash, 11 parts of sodium dodecylbenzene sulfonate, 3 parts of water reducer, 8 parts of calcium stearate and 195 parts of water according to weight parts, and prepare them for backup; the water reducer is FDN type naphthalene water reducer; Step S2: Mix silicate cement, fine sand, fly ash, sodium dodecylbenzene sulfonate, water reducing agent, calcium stearate and water evenly, then pour into a mold, vibrate and compact, place at room temperature for curing for 48 hours, and then demold to obtain foamed lightweight concrete.

[0021] Comparative Example 2: This comparative example is a method for preparing a foamed lightweight concrete, comprising the following steps: Step S5: weighing 220 parts of silicate cement, 280 parts of fine sand, 120 parts of fly ash, 46 parts of calcium carbonate whiskers, 11 parts of sodium dodecylbenzene sulfonate, 3 parts of water reducer, 8 parts of calcium stearate and 195 parts of water in parts by weight for backup; the calcium carbonate whiskers have an average length of 0.05 mm, an average diameter of 1.2 μm, an average tensile strength of 4800 MPa, and an average elastic modulus of 560 MPa; the water reducer is a FDN type naphthalene water reducer; Step S6: Mix silicate cement, fine sand, fly ash, calcium carbonate whisker, sodium dodecylbenzene sulfonate, water reducer, calcium stearate and water evenly, then pour into a mold, vibrate and compact, place at room temperature for curing for 48 hours, and then demold to obtain foamed lightweight concrete.

[0022] Comparative Example 3: This comparative example is a method for preparing a foamed lightweight concrete, comprising the following steps: Step S1: weigh 220 parts of Portland cement, 280 parts of fine sand, 120 parts of fly ash, 46 parts of calcium carbonate whiskers, 11 parts of sodium dodecylbenzene sulfonate, 3 parts of water reducer, 8 parts of calcium stearate, 7.7 parts of isocyanatepropyl triethoxysilane and 195 parts of water according to weight parts, and prepare them for backup; the calcium carbonate whiskers have an average length of 0.05 mm, an average diameter of 1.2 μm, an average tensile strength of 4800 MPa, and an average elastic modulus of 560 MPa; the water reducer is a FDN type naphthalene water reducer; Step S2: Mix silicate cement, fine sand, fly ash, calcium carbonate whisker, sodium dodecylbenzene sulfonate, water reducer, calcium stearate, triethoxypropyl isocyanate and water evenly, then pour into a mold, vibrate and compact, place at room temperature for curing for 48 hours, and then demold to obtain foamed lightweight concrete.

[0023] According to JGT266-2011 "Standard Specification for Foamed Concrete", the properties of the foamed lightweight concrete of Examples 1-3 and Comparative Examples 1-3 were tested, and the test results are shown in the following table:

[0024] Referring to the data in the above table, based on the comparison between Examples 1-3 and Comparative Examples 1-3, it can be seen that the foamed lightweight concrete in the present application has high compressive strength and low water absorption, giving it excellent mechanical properties and waterproof properties.

[0025] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0026] The above contents are merely examples and explanations of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the invention or exceed the scope defined in this application, they shall all fall within the protection scope of the present invention.

Claims

1. A foamed lightweight concrete, characterized in that: It includes the following components by weight: 200-220 parts of Portland cement, 250-280 parts of fine sand, 100-120 parts of fly ash, 18-46 parts of calcium carbonate whiskers, 3-11 parts of sodium dodecylbenzene sulfonate, 1-3 parts of water reducer, 4-8 parts of calcium stearate, 1.3-7.7 parts of performance enhancer and 175-195 parts of water; Wherein, the performance enhancer is prepared by the following steps: Step a1: 3,3',4,4'-biphenyltetracarboxylic dianhydride, concentrated sulfuric acid and N,N-dimethylformamide are added to a three-necked flask equipped with a stirrer and a thermometer, and stirred for reaction for 20-30 minutes at a temperature of 25-30°C and a stirring rate of 200-300 r / min, and then the temperature is raised to 50-55°C and the stirring reaction is continued for 1-2 hours, and then N-bromosuccinimide is added and the temperature is raised to 90-100°C and the stirring reaction is continued for 10-15 hours. After the reaction is completed, the reaction product is cooled to room temperature, and then added to ice water, and allowed to stand to precipitate, and then vacuum filtered, and the filter cake is washed with distilled water 2-3 times to obtain intermediate 1; Step a2: Add intermediate 1, perfluorohexylethanol, anhydrous potassium carbonate and tetrahydrofuran into a three-necked flask equipped with a stirrer, a thermometer, a gas guide tube and a reflux condenser, introduce nitrogen protection, stir and react for 20-30 minutes at a temperature of 25-30° C. and a stirring rate of 200-300 r / min, then heat to reflux and continue stirring and reacting for 5-6 hours. After the reaction is completed, the reaction product is cooled to room temperature, then vacuum filtered, and the filtrate is rotary evaporated to remove the solvent to obtain intermediate 2; Step a3: Add intermediate 2, ethanolamine and anhydrous ethanol to a three-necked flask equipped with a stirrer, a thermometer and an air guide tube, introduce nitrogen protection, stir the reaction at a temperature of 25-30° C. and a stirring rate of 200-300 r / min for 20-30 min, then heat to 80-85° C. and continue stirring the reaction for 8-10 h. After the reaction is completed, cool the reaction product to room temperature, then rotary evaporate to remove the solvent, and then place it in a vacuum drying oven and dry it at a temperature of 50-55° C. for 2-3 h to obtain intermediate 3; Step a4: Add intermediate 3, triethylamine and tetrahydrofuran to a three-necked flask equipped with a stirrer, a thermometer, an air duct and a reflux condenser, introduce nitrogen protection, stir and react for 20-30 minutes at a temperature of 25-30°C and a stirring rate of 200-300r / min, then add isocyanatepropyltriethoxysilane and continue stirring and reacting for 8-10 hours under the condition of raising the temperature to reflux. After the reaction, cool the reaction product to room temperature, then rotary evaporate to remove the solvent, then wash with petroleum ether 2-3 times, then place in a vacuum drying oven, and dry at a temperature of 70-75°C for 2-3 hours to obtain a performance enhancer.

2. The foamed lightweight concrete according to claim 1, characterized in that: The usage ratio of the 3,3',4,4'-biphenyltetracarboxylic dianhydride, concentrated sulfuric acid, N,N-dimethylformamide and N-bromosuccinimide in step a1 is 10 mmol: 10-15 mL: 40-50 mL: 25-45 mmol.

3. The foamed lightweight concrete according to claim 1, characterized in that: The mass fraction of the concentrated sulfuric acid in step a1 is 98%.

4. The foamed lightweight concrete according to claim 1, characterized in that: The usage ratio of the intermediate 1, perfluorohexylethanol, anhydrous potassium carbonate and tetrahydrofuran in step a2 is 10 mmol: 25-35 mmol: 40-50 mmol: 80-100 mL.

5. The foamed lightweight concrete according to claim 1, characterized in that: The usage ratio of the intermediate 2, ethanolamine and anhydrous ethanol in step a3 is 10mmol:20mmol:80-100mL.

6. The foamed lightweight concrete according to claim 1, characterized in that: The usage ratio of the intermediate 3, triethylamine, tetrahydrofuran and isocyanatepropyltriethoxysilane in step a4 is 10 mmol: 0.01-0.03 g: 100-120 mL: 22-25 mmol.

7. A method for preparing foamed lightweight concrete, characterized in that: The following steps are involved: Step 1: weigh 200-220 parts of Portland cement, 250-280 parts of fine sand, 100-120 parts of fly ash, 18-46 parts of calcium carbonate whiskers, 3-11 parts of sodium dodecylbenzene sulfonate, 1-3 parts of water reducer, 4-8 parts of calcium stearate, 1.3-7.7 parts of performance enhancer and 175-195 parts of water according to weight parts, and keep them in reserve; Step 2: Mix silicate cement, fine sand, fly ash, calcium carbonate whisker, sodium dodecylbenzene sulfonate, water reducer, calcium stearate, performance enhancer and water evenly, then pour into a mold, vibrate and compact, place at room temperature for curing for 48 hours, and then demold to obtain foamed lightweight concrete.

8. The method for preparing foamed lightweight concrete according to claim 7, characterized in that: The calcium carbonate whiskers have an average length of 0.05 mm, an average diameter of 1.2 μm, an average tensile strength of 4800 MPa, and an average elastic modulus of 560 MPa.

9. The method for preparing foamed lightweight concrete according to claim 7, characterized in that: The water reducer is a FDN type naphthalene water reducer.

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