Preparation method of biomass air entraining agent blended concrete

Abstract

The invention belongs to the technical field of waste biomass recycling. The invention relates to the field of concrete, in particular to a preparation method of biomass air entraining agent blended concrete. The method comprises the following specific extraction steps: preparing raw materials: taking the following components in parts by weight: 4 to 6 parts of water-absorbent resin, 20 to 30 parts of tea saponin, 1.2 to 1.8 parts of lignin, 300 to 400 parts of ordinary Portland cement, 80 to 100 parts of fly ash, 10 to 20 parts of silica fume, 300 to 350 parts of aggregate, 0.8 to 1.5 parts of water reducing agent, 0.4 to 0.6 part of foam stabilizer and 0.1 to 0.2 part of retarder; mixing the raw materials: mixing tea saponin, water-absorbent resin, lignin and water, and foaming to form a foam liquid with the foam density of 55-65 kg / m < 3 >; wherein the dosage of the water is 40-50 times of the mass of the tea saponin; after the other raw materials are subjected to dry mixing and uniform stirring, water is added according to the water-binder ratio of 0.5-0.6, and prefabricated slurry is formed; and injecting the foam liquid into the prefabricated slurry, uniformly stirring at a low speed, pouring, and carrying out film covering maintenance, thereby completing the preparation of the biomass air entraining agent blended concrete.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste biomass recycling, and more specifically, relates to a method for preparing concrete mixed with a biomass air entraining agent. Background Art

[0002] Foamed concrete is a lightweight concrete and its components containing a large number of closed pores formed by mechanically making foaming agent aqueous solution into foam, then mixing the foam into various cement mixtures, evenly stirring, pouring and curing. The material has excellent properties such as light weight and high strength, energy saving and waste recycling, and thermal insulation. The quality of foamed concrete is inseparable from the performance of the foaming agent. A good foaming agent is the core element for preparing high-quality foamed concrete.

[0003] Concrete foaming agents are mostly surfactants. According to the international classification of surfactants, foaming agents can be classified into anionic foaming agents, cationic foaming agents, amphoteric foaming agents and non-ionic foaming agents. Tea saponin, also known as camellia saponin, is a mixture of saponins found in tea seeds and tea leaves. At the same time, tea saponin is also a small molecule substance with excellent performance and a green natural surfactant.

[0004] However, when tea saponin, a natural surfactant, is directly added to the concrete system, it still faces the disadvantage of mediocre bubble effect, especially insufficient foam stability, which leads to the disadvantage that the air entraining effect of concrete is not as good as expected. Summary of the invention

[0005] The technical problem to be solved by the present invention is that the foaming effect of conventional foamed concrete made of tea saponin as a biomass air entraining agent is generally poor, especially the stability of the foam is insufficient. Based on the above problem, the present invention provides a method for preparing concrete mixed with a biomass air entraining agent.

[0006] The purpose of the present invention is to provide a method for preparing biomass air entraining agent mixed concrete.

[0007] The above-mentioned purpose of the present invention is achieved through the following technical solutions: A method for preparing biomass air-entraining agent mixed concrete, the specific preparation steps comprising: Raw materials preparation: By weight, take 4-6 parts of water-absorbing resin, 20-30 parts of tea saponin, 1.2-1.8 parts of lignin, 300-400 parts of ordinary Portland cement, 80-100 parts of fly ash, 10-20 parts of silica fume, 300-350 parts of aggregate, 0.8-1.5 parts of water reducing agent, 0.4-0.6 parts of foam stabilizer, and 0.1-0.2 parts of retarder; Mixing of raw materials: Mix tea saponin, water-absorbing resin, lignin and water and foam them to form a foam liquid with a foam density of 55-65kg / m3; wherein the amount of water used is 40-50 times the mass of the tea saponin; After dry mixing the remaining raw materials and stirring them evenly, add water according to a water-binder ratio of 0.5-0.6 to form a prefabricated slurry; The foam liquid is injected into the prefabricated slurry, stirred evenly at a low speed, poured, and then covered and cured to complete the preparation of the biomass air-entraining agent mixed concrete.

[0008] Beneficial effects of the above technical solution: The inventors found in the research process that for the foam concrete system, since the hydration of cement in the concrete during the preparation process generates hydration heat, as the temperature of the concrete rises, the foam film produced by foaming may become thinner or even rupture, thereby affecting the stability of the bubbles; on the other hand, as the temperature rises, the bubbles will merge quickly, causing the size of the bubbles to become larger and the distribution to become uneven, ultimately affecting the foaming effect; in particular, for biomass-based air-entraining agents, that is, the air-entraining agents such as tea saponin added in the present application, they may even hydrolyze and fail during the process of continuously increasing temperature, reducing the number of bubbles and affecting the foaming effect; Based on the above findings, the above technical solution of the present application adopts compounding by adding water-absorbing resin and lignin to solve the technical problem; specifically, the water-absorbing resin can retain a large amount of water after absorbing water during the manufacturing process of concrete, and quickly forms a gel-like substance, thereby enhancing the strength and elasticity of the bubble film, thereby improving the stability of the foam liquid during the manufacturing process; In addition, during the mixing and pouring process with the prefabricated slurry, the hydration of cement generates hydration heat, and the gel-like substance formed by the water-absorbing resin has a good temperature buffering capacity, which can alleviate the influence of the hydration heat on the foaming of tea saponin to a certain extent; in addition, during the mixing process of the foam liquid and the prefabricated slurry, the foaming process is still accompanied by low-speed stirring, and the presence of the gel-like substance formed by the water-absorbing resin can help the foam to be more uniform; Furthermore, the inventors found that during the pouring and film-covering curing process, the alkaline environment in the concrete still has a continuous adverse effect on the stable foam system formed by tea saponin and water-absorbing resin. The alkaline environment will cause the foam stability to decrease, resulting in the foam rupture in the later stage. By introducing lignin, it can undergo oxidative self-polymerization under the action of dissolved oxygen in the water of the concrete system in an alkaline environment and the heat generated by cement hydration during the later pouring and film-covering curing process, thereby providing strength for the foam liquid film in the later stage, that is, during the pouring and curing process, and reducing its rupture; Therefore, the lignin and the water-absorbing resin are combined in the early and late stages of the concrete manufacturing process to ensure the stability of the foaming process and maintain the foaming effect.

[0009] Furthermore, the water-absorbing resin is selected from any one of sodium polyacrylate, polyacrylamide and polyvinyl alcohol.

[0010] The above technical solution further adopts an organic polymer water-absorbing resin, the polar functional groups in the molecular structure of which can form hydrogen bond interaction forces with tea saponin, so that the gel-like substance formed by the organic polymer water-absorbing resin in the liquid film formed by the foaming of tea saponin can play a good foam supporting effect.

[0011] Furthermore, the aggregate comprises the following raw material components in parts by weight: 280-300 parts of fine sand, 60-80 parts of expanded perlite, 4-8 parts of expanded graphite; Wherein, the D50 of the expanded graphite is 100-120 μm.

[0012] Furthermore, the expanded graphite is spherical expanded graphite, and the preparation steps of the spherical expanded graphite include: By weight, 80-100 parts of expanded graphite, 400-420 parts of water, and 10-12 parts of sodium polystyrene sulfonate are mixed, and then ultrasonically dispersed for 30-60 minutes at a frequency of 180-220 kHz, and then the dispersion is sprayed and granulated to obtain spherical expanded graphite.

[0013] In the above technical solution, expanded graphite is used as part of the aggregate. Its main function is that the expanded graphite is light in weight, and it is also easy to be compatible with the foam formed by the biomass air-entraining agent. Its properties are stable during the hydration process of concrete. Moreover, it has excellent thermal conductivity. During the hydration heat generation process in the system, it is beneficial to conduct the internal heat to the outside, avoiding excessive concentration of heat inside and affecting the stability of the internal foam.

[0014] Furthermore, the water reducer is selected from any one of lignin sulfonate water reducer, polycarboxylic acid water reducer, aliphatic water reducer, aminosulfonate water reducer, melamine water reducer and naphthalene water reducer.

[0015] Furthermore, the foam stabilizer is selected from any one of sodium lauryl sulfate, sodium α-olefin sulfonate, sodium fatty alcohol polyoxyethylene ether sulfate, dodecyl dimethyl amine oxide, and alkyl alcohol amide.

[0016] Furthermore, the retarder is selected from any one of sodium pyrophosphate, sodium tripolyphosphate, borax and sodium fluorosilicate.

[0017] Furthermore, the low-speed stirring comprises: The stirring speed was 65-85 r / min, and the stirring was continued for 15-25 min.

[0018] Furthermore, the low-speed stirring evenly also includes: At a stirring speed of 65-85r / min, continue stirring and mixing for 15-25 minutes, and cool the concrete slurry to maintain the temperature below 25°C during low-speed stirring; Wherein, the cooling is performed by water cooling.

[0019] The above technical solution further controls the temperature during the low-speed stirring process so that the whole system is carried out at a relatively low temperature, thereby making the early foam dense and stable and avoiding premature foam bursting. DETAILED DESCRIPTION

[0020] The present invention is further described below with reference to specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art.

[0021] Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0022] In the monodisperse hollow nanoparticles mentioned below, the specific meaning of hollow is that bubbles are introduced by using emulsifiers or the like during the preparation process, so that the inside of the particles is in a hollow state, as distinguished from a completely solid state. Example 1

[0023] Raw materials preparation: According to weight, take 4 parts of water-absorbing resin, 20 parts of tea saponin, 1.2 parts of lignin, 300 parts of ordinary Portland cement, 80 parts of fly ash, 10 parts of silica fume, 300 parts of aggregate, 0.8 parts of water reducing agent, 0.4 parts of foam stabilizer, and 0.1 parts of retarder; The water-absorbing resin is selected from sodium polyacrylate; The aggregate comprises the following raw materials in parts by weight: 280 parts fine sand, 60 parts expanded perlite, 4 parts expanded graphite; Wherein, the D50 of the expanded graphite is 100 μm; The expanded graphite is spherical expanded graphite, and the preparation steps of the spherical expanded graphite include: 80 parts of expanded graphite, 400 parts of water and 10 parts of sodium polystyrene sulfonate were mixed by weight, and then ultrasonically dispersed for 30 minutes at a frequency of 180kHz, and then the dispersion was transported to a spray dryer through a screw pump, and spray granulated and sieved under the conditions of an inlet air temperature of 135°C, an outlet air temperature of 115°C, a feed rate of 80g / min and a main disk speed of 8000r / min to obtain spherical expanded graphite; The water reducing agent is selected from sodium lignin sulfonate; The foam stabilizer is selected from sodium lauryl sulfate; The retarder is selected from sodium pyrophosphate; Mixing of raw materials: Tea saponin, water-absorbing resin, lignin and water are mixed and foamed to form a foam with a density of 55 kg / m 3 wherein the amount of water is 40 times the quality of the tea soap; The remaining raw materials were dry mixed with a stirrer at a speed of 120 r / min for 15 minutes, and then water was added according to a water-binder ratio of 0.5, and the mixture was continued to be mixed with a stirrer for 8 minutes to form a prefabricated slurry; The foam liquid is injected into the prefabricated slurry, stirred at a low speed, poured, and then covered, and then left to stand and cure at room temperature for 28 days, thus completing the preparation of the biomass air entraining agent mixed concrete; The low speed stirring is uniform: The mixing was continued for 15 minutes at a stirring speed of 65 r / min, and the temperature of the concrete slurry was maintained below 25°C by cooling during the low-speed mixing process; Wherein, the cooling is performed by water cooling. Example 2

[0024] Raw materials preparation: By weight, take 5 parts of water-absorbing resin, 26 parts of tea saponin, 1.5 parts of lignin, 340 parts of ordinary Portland cement, 90 parts of fly ash, 15 parts of silica fume, 320 parts of aggregate, 0.9 parts of water reducing agent, 0.5 parts of foam stabilizer, and 0.12 parts of retarder; The water-absorbing resin is selected from polyacrylamide; The aggregate comprises the following raw materials in parts by weight: 290 parts fine sand, 70 parts expanded perlite, 6 parts expanded graphite; Wherein, the D50 of the expanded graphite is 110 μm; The expanded graphite is spherical expanded graphite, and the preparation steps of the spherical expanded graphite include: 90 parts of expanded graphite, 410 parts of water and 11 parts of sodium polystyrene sulfonate were mixed by weight, and then ultrasonically dispersed for 50 minutes at a frequency of 200kHz. The dispersion was then transported to a spray dryer through a screw pump, and spray granulated and sieved under the conditions of an inlet air temperature of 138°C, an outlet air temperature of 116°C, a feed rate of 90g / min and a main disk speed of 8000r / min to obtain spherical expanded graphite; The water reducing agent is selected from sodium lignin sulfonate; The foam stabilizer is selected from sodium α-olefin sulfonate; The retarder is selected from sodium tripolyphosphate; Mixing of raw materials: Mix tea saponin, water-absorbing resin, lignin and water and foam them to form a foam liquid with a foam density of 60kg / m3; wherein the amount of water used is 45 times the mass of the tea saponin; The remaining raw materials were dry mixed with a stirrer at a speed of 140 r / min for 20 minutes, and then water was added according to a water-binder ratio of 0.55, and the mixture was continued to be mixed with the stirrer for 12 minutes to form a prefabricated slurry; The foam liquid is injected into the prefabricated slurry, stirred at a low speed, poured, and then covered, and then left to stand and cure at room temperature for 28 days, thus completing the preparation of the biomass air entraining agent mixed concrete; The low speed stirring is uniform: The mixing was continued for 25 min at a stirring speed of 85 r / min, and the temperature of the concrete slurry was maintained below 25°C by cooling during the low-speed mixing process; Wherein, the cooling is performed by water cooling. Example 3

[0025] Raw materials preparation: According to weight, take 6 parts of water-absorbing resin, 30 parts of tea saponin, 1.8 parts of lignin, 400 parts of ordinary Portland cement, 100 parts of fly ash, 20 parts of silica fume, 350 parts of aggregate, 1.5 parts of water reducing agent, 0.6 parts of foam stabilizer, and 0.2 parts of retarder; The water-absorbing resin is selected from polyvinyl alcohol; The aggregate comprises the following raw materials in parts by weight: 300 parts of fine sand, 80 parts of expanded perlite, 8 parts of expanded graphite; Wherein, the D50 of the expanded graphite is 120 μm; The expanded graphite is spherical expanded graphite, and the preparation steps of the spherical expanded graphite include: By weight, 100 parts of expanded graphite, 420 parts of water, and 12 parts of sodium polystyrene sulfonate were mixed, and then ultrasonically dispersed for 60 minutes at a frequency of 220kHz, and then the dispersion was transported to a spray dryer through a screw pump, and spray granulated and sieved under the conditions of an inlet air temperature of 140°C, an outlet air temperature of 120°C, a feed rate of 100g / min, and a main disk speed of 8000r / min to obtain spherical expanded graphite; The water reducing agent is selected from sodium lignin sulfonate; The foam stabilizer is selected from dodecyl dimethyl amine oxide; The retarder is selected from borax; Mixing of raw materials: Mix tea saponin, water-absorbing resin, lignin and water and foam them to form a foam liquid with a foam density of 65kg / m3; wherein the amount of water used is 50 times the mass of the tea saponin; The remaining raw materials were dry-mixed with a stirrer at a speed of 150 r / min for 25 minutes, and then water was added according to a water-binder ratio of 0.6, and the stirring was continued for 15 minutes to form a prefabricated slurry; The foam liquid is injected into the prefabricated slurry, stirred at a low speed, poured, and then covered, and then left to stand and cure at room temperature for 28 days, thus completing the preparation of the biomass air entraining agent mixed concrete; The low speed stirring is uniform: The mixing was continued for 25 min at a stirring speed of 85 r / min, and the temperature of the concrete slurry was maintained below 25°C by cooling during the low-speed mixing process; Wherein, the cooling is performed by water cooling. Example 4

[0026] Compared with Example 1, this embodiment differs in that no expanded graphite is added, and other conditions remain unchanged. Example 5

[0027] The present embodiment is different from the embodiment 1 in that during the low-speed stirring process, the temperature of the concrete slurry is controlled at 35° C., and the other conditions remain unchanged.

[0028] Comparative Example 1 The difference between this comparative example and Example 1 is that no lignin is added, and the other conditions remain unchanged.

[0029] Comparative Example 2 The difference between this comparative example and Example 1 is that no water-absorbing resin is added, and other conditions remain unchanged.

[0030] The performance tests were performed on the products obtained in the above examples and comparative examples. The specific test methods and test results are as follows: Porosity test: The porosity was tested according to ASTM C642 standard. The specific test results are shown in Table 1. Compressive strength test: According to ASTM C39 standard, the compressive strength of concrete was tested. The specific test results are shown in Table 1; Water absorption test: According to ASTM C642 standard, the water absorption is tested. The specific test results are shown in Table 1; Table 1: Product performance test results

[0031] It can be seen from the test results in Table 1 that, thanks to the good foaming effect, the product has excellent porosity, water absorption and mechanical properties.

[0032] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A method for preparing biomass air-entraining agent mixed concrete, characterized in that: The specific preparation steps include: Raw materials preparation: By weight, take 4-6 parts of water-absorbing resin, 20-30 parts of tea saponin, 1.2-1.8 parts of lignin, 300-400 parts of ordinary Portland cement, 80-100 parts of fly ash, 10-20 parts of silica fume, 300-350 parts of aggregate, 0.8-1.5 parts of water reducing agent, 0.4-0.6 parts of foam stabilizer, and 0.1-0.2 parts of retarder; Mixing of raw materials: Mix tea saponin, water-absorbing resin, lignin and water and foam them to form a foam with a density of 55-65kg / m 3 wherein the amount of water is 40-50 times the quality of the tea soap; After dry mixing the remaining raw materials and stirring them evenly, add water according to a water-binder ratio of 0.5-0.6 to form a prefabricated slurry; The foam liquid is injected into the prefabricated slurry, stirred evenly at a low speed, poured, and then covered and cured to complete the preparation of the biomass air-entraining agent mixed concrete.

2. The method for preparing concrete mixed with biomass air entraining agent according to claim 1, characterized in that: The water-absorbing resin is selected from any one of sodium polyacrylate, polyacrylamide and polyvinyl alcohol.

3. The method for preparing concrete mixed with biomass air entraining agent according to claim 1, characterized in that: The aggregate comprises the following raw materials in parts by weight: 280-300 parts of fine sand, 60-80 parts of expanded perlite, 4-8 parts of expanded graphite; Wherein, the D50 of the expanded graphite is 100-120 μm.

4. The method for preparing concrete mixed with biomass air entraining agent according to claim 3, characterized in that: The expanded graphite is spherical expanded graphite, and the preparation steps of the spherical expanded graphite include: By weight, 80-100 parts of expanded graphite, 400-420 parts of water, and 10-12 parts of sodium polystyrene sulfonate are mixed, and then ultrasonically dispersed for 30-60 minutes at a frequency of 180-220 kHz, and then the dispersion is sprayed and granulated to obtain spherical expanded graphite.

5. The method for preparing concrete mixed with biomass air entraining agent according to claim 1, characterized in that: The water reducer is selected from any one of lignin sulfonate water reducer, polycarboxylic acid water reducer, aliphatic water reducer, aminosulfonate water reducer, melamine water reducer and naphthalene water reducer.

6. The method for preparing concrete mixed with biomass air entraining agent according to claim 1, characterized in that: The foam stabilizer is selected from any one of sodium lauryl sulfate, sodium α-olefin sulfonate, sodium fatty alcohol polyoxyethylene ether sulfate, dodecyl dimethyl amine oxide, and alkyl alcohol amide.

7. The method for preparing concrete mixed with biomass air entraining agent according to claim 1, characterized in that: The retarder is selected from any one of sodium pyrophosphate, sodium tripolyphosphate, borax and sodium fluorosilicate.

8. The method for preparing concrete mixed with biomass air entraining agent according to claim 1, characterized in that: The low-speed stirring evenly comprises: The stirring speed was 65-85 r / min, and the stirring was continued for 15-25 min.

9. The method for preparing concrete mixed with biomass air entraining agent according to claim 8, characterized in that: The low-speed stirring evenly also includes: At a stirring speed of 65-85r / min, continue stirring and mixing for 15-25 minutes, and cool the concrete slurry to maintain the temperature below 25°C during low-speed stirring; Wherein, the cooling is performed by water cooling.

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