Preparation method of biomass air-entraining agent blended concrete

Abstract

The present invention belongs to the technical field of waste biomass recycling. More specifically, it relates to a preparation method of biomass air-entraining agent blended concrete. The specific extraction steps of the present invention include: Raw material 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 reducer, 0.4-0.6 parts of foam stabilizer, 0.1-0.2 parts of retarder; Mixing of raw materials: Mix tea saponin, water-absorbing resin, lignin and water and then foam to form a foam liquid with a foam density of 55-65 kg / m3; wherein, the amount of water used is 40-50 times the mass of the tea saponin; After dry-mixing and stirring the remaining raw materials evenly, add water according to a water-binder ratio of 0.5-0.6 to form a precast slurry; Inject the foam liquid into the precast slurry, stir evenly at a low speed, pour, and then cure by film covering to complete 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. More specifically, it relates to a preparation method of biomass air-entraining agent blended concrete. Background Art

[0002] Foamed concrete is made by mechanically making an aqueous solution of a foaming agent into foam, and then mixing the foam into various cement mixtures. After uniform stirring, pouring and molding, it is cured to form a lightweight concrete and its components containing a large number of closed pores. Its materials have excellent properties such as light weight and high strength, energy conservation and waste utilization, heat preservation and heat 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. Referring to the classification method of surfactants in the world, the foaming agents can be classified into anionic foaming agents, cationic foaming agents, amphoteric foaming agents and non-ionic foaming agents, etc. Tea saponin, also known as camellia saponin, is a saponin mixture present in tea seeds and tea leaves seeds. At the same time, tea saponin is also a small molecule substance and a green natural surfactant with very excellent performance.

[0004] However, when tea saponin, a natural surfactant, is directly added to the concrete system, it still needs to face the general bubble effect, especially the insufficient stability of the foam, resulting in the air-entraining effect on the concrete not meeting the expectations. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: when traditional tea saponin is used as a biomass air-entraining agent to manufacture foamed concrete, its foaming effect is general, especially the stability of the foam is insufficient. Based on the above problems, the present invention provides a preparation method of biomass air-entraining agent blended concrete.

[0006] The object of the present invention is to provide a preparation method of biomass air-entraining agent blended concrete.

[0007] The above object of the present invention is achieved by the following technical solutions:

[0008] A preparation method of biomass air-entraining agent blended concrete, the specific preparation steps include:

[0009] Raw material preparation:

[0010] 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, 0.1-0.2 parts of retarder;

[0011] Mixing of raw materials:

[0012] Mix tea saponin, water-absorbing resin, lignin and water and foam them to form a foam liquid with a foam density of 55-65 kg / m3; among them, the amount of water used is 40-50 times the mass of the tea saponin;

[0013] After dry-mixing and stirring the remaining raw materials evenly, add water according to a water-binder ratio of 0.5-0.6 to form a precast slurry;

[0014] Inject the foam liquid into the precast slurry, stir evenly at a low speed, pour it, and then cure it with a film covering to complete the preparation of the biomass air-entraining agent blended concrete.

[0015] Advantages of the above technical solution:

[0016] The inventor found during the research process that for the foam concrete system, due to the hydration heat generated by the cement hydration in the concrete during the preparation process, as the temperature of the concrete rises, it may cause the foam film generated by foaming to become thinner or even rupture, thus affecting the stability of the bubbles; on the other hand, as the temperature rises, the bubbles will quickly merge with each other, resulting in larger bubble sizes and uneven distributions, ultimately affecting the foaming effect; in particular, for biomass air-entraining agents, that is, the tea saponin added in this application, it may even hydrolyze and fail during the process of continuous temperature rise, reducing the number of bubbles and affecting the foaming effect;

[0017] Based on the above findings, the above technical solution of this application uses the addition of water-absorbing resin and lignin for compounding to solve this technical problem; specifically, among them, the water-absorbing resin can retain a large amount of water after absorbing water during the manufacturing process of the concrete and quickly form a gel-like substance, enhancing the strength and elasticity of the foam film, thereby improving the stability during the manufacturing process of the foam liquid;

[0018] In addition, during the mixing and pouring process with the precast slurry, due to the hydration heat generated by the cement hydration, and the gel-like substance formed by the water-absorbing resin has good temperature buffering ability, it can alleviate the influence of the hydration heat on the foaming of tea saponin to a certain extent; in addition, due to the foaming process still occurring during the mixing process of the foam liquid and the precast slurry under low-speed stirring, the presence of the gel-like substance formed by the water-absorbing resin can help the foam to be more uniform;

[0019] Furthermore, the inventor found that during the pouring and film curing processes, the alkaline environment in the concrete still has a continuous adverse effect on the stable foam system formed by tea saponin and the water-absorbing resin. The alkaline environment will cause the foam stability to decrease and lead to the rupture of the foam in the later stage. By introducing lignin, under the alkaline environment, under the action of dissolved oxygen in the concrete system water, and under the action of the heat generated by cement hydration during the later pouring and film curing processes, it can undergo oxidative self-polymerization, so that in the later stage, that is, during the pouring and curing processes, it can provide strength for the liquid film of the foam and reduce its rupture.

[0020] Thus, lignin and the water-absorbing resin cooperate in the early and later stages during the manufacturing process of the concrete, ensuring stability during the foaming process and maintaining the foaming effect.

[0021] Further, the water-absorbing resin is selected from any one of sodium polyacrylate, polyacrylamide, and polyvinyl alcohol.

[0022] In the above technical solution, by further using a water-absorbing resin of the organic polymer type, the polar functional groups in its molecular structure can form hydrogen bond interaction forces with tea saponin. Thus, in the liquid film formed by the foaming of tea saponin, the gel-like substance formed by the water-absorbing resin of the organic polymer type can play a good foam support effect.

[0023] Further, the aggregate comprises raw materials in the following parts by weight:

[0024] 280 - 300 parts of fine sand, 60 - 80 parts of expanded perlite, 4 - 8 parts of expanded graphite;

[0025] Among them, the D50 of the expanded graphite is 100 - 120 μm.

[0026] Further, the expanded graphite is spherical expanded graphite, and the preparation steps of the spherical expanded graphite include:

[0027] By weight, take 80 - 100 parts of expanded graphite, 400 - 420 parts of water, 10 - 12 parts of sodium polystyrene sulfonate, mix them, and perform ultrasonic dispersion for 30 - 60 min under the condition of a frequency of 180 - 220 kHz, and then spray granulate the dispersion liquid to obtain spherical expanded graphite.

[0028] In the above technical solution, by using expanded graphite as part of the aggregate, its main function is that expanded graphite is light in weight, it is also easy to be affinity with the foam formed by the biomass air-entraining agent, its properties are stable during the hydration process of the concrete, and it has excellent thermal conductivity. During the heat generation process of hydration in the system, it is beneficial to conduct the internal heat to the outside, avoiding excessive heat concentration inside and affecting the internal foam stability.

[0029] Further, the water reducing agent is selected from any one of lignosulfonate water reducing agent, polycarboxylate water reducing agent, aliphatic water reducing agent, amino sulfonate water reducing agent, melamine water reducing agent, and naphthalene water reducing agent.

[0030] Further, the foam stabilizer is selected from any one of sodium dodecyl sulfate, α-olefin sulfonate, sodium fatty alcohol polyoxyethylene ether sulfate, dodecyldimethylamine oxide, and alkyl alkanolamide.

[0031] Further, the retarder is selected from any one of sodium pyrophosphate, sodium tripolyphosphate, borax, and sodium fluorosilicate.

[0032] Further, the low-speed uniform stirring includes:

[0033] Under the condition that the stirring speed is 65 - 85 r / min, continuously stir and mix for 15 - 25 min.

[0034] Further, the low-speed uniform stirring also includes:

[0035] Under the condition that the stirring speed is 65 - 85 r / min, continuously stir and mix for 15 - 25 min, and through cooling, to maintain the temperature of the concrete slurry below 25 °C during the low-speed stirring process;

[0036] Among them, the cooling is carried out by means of water cooling.

[0037] The above technical solution controls the temperature during the low-speed stirring process further, so that the whole system proceeds at a relatively low temperature, to make the foam in the early stage dense and stable, and avoid premature rupture of the foam. Specific Embodiments

[0038] The following specific embodiments are used to further illustrate the present invention, but the embodiments 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 technical field.

[0039] Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0040] In the monodisperse hollow nanoparticles mentioned below, the specific meaning of "hollow" is that during the preparation process, by using emulsifiers and other means, air bubbles are introduced so that the inside of the particles is in a hollow state, to distinguish from the completely solid state. Example 1

[0041] Raw material preparation:

[0042] By 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 part of water reducing agent, 0.4 part of foam stabilizer, and 0.1 part of retarder;

[0043] The water-absorbing resin is selected from sodium polyacrylate;

[0044] The aggregate consists of raw materials in the following parts by weight:

[0045] 280 parts of fine sand, 60 parts of expanded perlite, and 4 parts of expanded graphite;

[0046] Among them, the D50 of the expanded graphite is 100 μm;

[0047] The expanded graphite is spherical expanded graphite, and the preparation steps of the spherical expanded graphite include:

[0048] By weight, take 80 parts of expanded graphite, 400 parts of water, and 10 parts of sodium polystyrene sulfonate. After mixing, ultrasonically disperse for 30 min under the condition of a frequency of 180 kHz, and then pump the dispersion liquid to a spray dryer. Under the conditions of an inlet air temperature of 135 °C, an outlet air temperature of 115 °C, a feeding rate of 80 g / min, and a main disk rotation speed of 8000 r / min, spray granulate and screen to obtain spherical expanded graphite;

[0049] The water reducing agent is selected from sodium lignosulfonate;

[0050] The foam stabilizer is selected from sodium dodecyl sulfate;

[0051] The retarder is selected from sodium pyrophosphate;

[0052] Mixing of raw materials:

[0053] Mix tea saponin, water-absorbing resin, lignin and water and foam to form a foam liquid with a foam density of 55 kg / m 3 ; Among them, the amount of water used is 40 times the mass of the tea saponin;

[0054] Dry-mix and stir the remaining raw materials with a stirrer at a rotation speed of 120 r / min for 15 min, then add water according to a water-cement ratio of 0.5, and continue to stir and mix with a stirrer for 8 min to form a precast slurry;

[0055] Inject the foam liquid into the precast slurry, stir evenly at a low speed, pour, and then after film covering, cure statically at room temperature for 28 d to complete the preparation of the biomass air-entraining agent blended concrete;

[0056] The low-speed stirring evenly is:

[0057] Under the condition that the stirring speed is 65 r / min, continuously stir and mix for 15 min, and through cooling, to maintain the temperature of the concrete slurry below 25 °C during the low-speed stirring process;

[0058] Among them, the cooling is carried out by means of water cooling. Example 2

[0059] Raw material preparation:

[0060] 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 part of water reducer, 0.5 part of foam stabilizer, 0.12 part of retarder;

[0061] The water-absorbing resin is selected from polyacrylamide;

[0062] The aggregate consists of the following raw materials by weight:

[0063] 290 parts of fine sand, 70 parts of expanded perlite, 6 parts of expanded graphite;

[0064] Among them, the D50 of the expanded graphite is 110 μm;

[0065] The expanded graphite is spherical expanded graphite, and the preparation steps of the spherical expanded graphite include:

[0066] By weight, take 90 parts of expanded graphite, 410 parts of water, 11 parts of sodium polystyrene sulfonate, mix them, and under the condition of an ultrasonic dispersion frequency of 200 kHz for 50 min, then convey the dispersion liquid to a spray dryer, and under the conditions of an inlet air temperature of 138 °C, an outlet air temperature of 116 °C, a feeding rate of 90 g / min, and a main disk rotation speed of 8000 r / min, spray granulate and screen to obtain spherical expanded graphite;

[0067] The water reducer is selected from sodium lignosulfonate;

[0068] The foam stabilizer is selected from α-olefin sulfonate;

[0069] The retarder is selected from sodium tripolyphosphate;

[0070] Mixing of raw materials:

[0071] Mix tea saponin, water-absorbing resin, lignin and water and foam to form a foam liquid with a foam density of 60 kg / m3; among them, the amount of water used is 45 times the mass of the tea saponin;

[0072] After dry-mixing and stirring the remaining raw materials with a stirrer at a speed of 140 r / min for 20 min, water is added according to a water-cement ratio of 0.55, and then the mixture is continuously stirred with the stirrer for 12 min to form a precast slurry;

[0073] The foam liquid is injected into the precast slurry. After stirring evenly at a low speed, it is poured, and then after film covering, it is left to cure at room temperature for 28 d, thus completing the preparation of the concrete mixed with the biomass air-entraining agent;

[0074] The low-speed stirring evenly means:

[0075] Under the condition that the stirring speed is 85 r / min, the mixture is continuously stirred for 25 min, and through cooling, the temperature of the concrete slurry is maintained below 25 °C during the low-speed stirring process;

[0076] Among them, the cooling is carried out by means of water cooling. Example 3

[0077] Raw material preparation:

[0078] By weight, 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 reducer, 0.6 part of foam stabilizer, and 0.2 part of retarder are taken;

[0079] The water-absorbing resin is selected from polyvinyl alcohol;

[0080] The aggregate consists of the following raw materials by weight:

[0081] 300 parts of fine sand, 80 parts of expanded perlite, and 8 parts of expanded graphite;

[0082] Among them, the D50 of the expanded graphite is 120 μm;

[0083] The expanded graphite is spherical expanded graphite, and the preparation steps of the spherical expanded graphite include:

[0084] By weight, 100 parts of expanded graphite, 420 parts of water, and 12 parts of sodium polystyrene sulfonate are taken. After mixing, they are ultrasonically dispersed for 60 min under the condition of a frequency of 220 kHz, and then the dispersion liquid is transported to a spray dryer by a screw pump. Under the conditions of an inlet air temperature of 140 °C, an outlet air temperature of 120 °C, a feeding rate of 100 g / min, and a main disk rotation speed of 8000 r / min, spray granulation and screening are carried out to obtain spherical expanded graphite;

[0085] The water reducer is selected from sodium lignosulfonate;

[0086] The foam stabilizer is selected from dodecyldimethylamine oxide;

[0087] The retarder is selected from borax;

[0088] Mixing of raw materials:

[0089] Mix tea saponin, water-absorbing resin, lignin and water and then foam to form a foam liquid with a foam density of 65 kg / m3; among them, the amount of water used is 50 times the mass of the tea saponin;

[0090] Dry-mix and stir the remaining raw materials with a stirrer at a speed of 150 r / min for 25 min, then add water according to a water-cement ratio of 0.6, and continue to stir and mix with the stirrer for 15 min to form a precast slurry;

[0091] Inject the foam liquid into the precast slurry, stir evenly at a low speed, then pour, and after covering with a film, let it stand for curing at room temperature for 28 d to complete the preparation of the biomass air-entraining agent blended concrete;

[0092] The low-speed stirring evenly is as follows:

[0093] Under the condition that the stirring speed is 85 r / min, continuously stir and mix for 25 min, and through cooling, maintain the temperature of the concrete slurry below 25 °C during the low-speed stirring process;

[0094] Among them, the cooling is carried out by means of water cooling. Example 4

[0095] Compared with Example 1, the difference in this example is that expanded graphite is not added, and the other conditions remain unchanged. Example 5

[0096] Compared with Example 1, the difference in this example is that during the low-speed stirring process, the temperature of the concrete slurry is controlled at 35 °C, and the other conditions remain unchanged.

[0097] Comparative Example 1

[0098] Compared with Example 1, the difference in this comparative example is that lignin is not added, and the other conditions remain unchanged.

[0099] Comparative Example 2

[0100] Compared with Example 1, the difference in this comparative example is that the water-absorbing resin is not added, and the other conditions remain unchanged.

[0101] Perform performance tests on the products obtained from the above examples and comparative examples. The specific test methods and test results are as follows:

[0102] Porosity test: Test its porosity according to ASTM C642 standard, and the specific test results are shown in Table 1;

[0103] Compressive strength test: According to ASTM C39 standard, the compressive strength of concrete was tested, and the specific test results are shown in Table 1;

[0104] Water absorption test: According to ASTM C642 standard, its water absorption was tested, and the specific test results are shown in Table 1;

[0105] Table 1: Test results of product performance

[0106]

[0107] It can be seen from the test results in Table 1 that due to the good foaming effect, the porosity, water absorption and mechanical properties of the product are excellent.

[0108] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A preparation method of biomass air-entraining agent blended concrete, characterized in that, The specific preparation steps include: Raw material 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, 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 solution with a foam density of 55-65 kg / m 3 ; wherein, the amount of water used is 40-50 times the mass of the tea saponin; After dry-mixing and stirring the remaining raw materials evenly, add water according to a water-binder ratio of 0.5 - 0.6 to form a precast slurry; Inject the foam liquid into the precast slurry, stir evenly at a low speed, pour, and then cure under film covering to complete the preparation of the biomass air-entraining agent blended concrete.

2. The preparation method of a biomass air-entraining agent blended concrete 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 preparation method of a biomass air-entraining agent blended concrete according to claim 1, characterized in that, The aggregate consists of the following raw materials by weight: 280 - 300 parts of fine sand, 60 - 80 parts of expanded perlite, 4 - 8 parts of expanded graphite; Among them, the D50 of the expanded graphite is 100 - 120 μm.

4. The preparation method of a biomass air-entraining agent blended concrete 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, take 80 - 100 parts of expanded graphite, 400 - 420 parts of water, 10 - 12 parts of sodium polystyrene sulfonate, mix them, and ultrasonically disperse for 30 - 60 min under the condition of a frequency of 180 - 220 kHz, and then spray granulate the dispersion liquid to obtain spherical expanded graphite.

5. The preparation method of a biomass air-entraining agent blended concrete according to claim 1, characterized in that, The water-reducing agent is selected from any one of lignosulfonate water-reducing agents, polycarboxylate water-reducing agents, aliphatic water-reducing agents, amino sulfonate water-reducing agents, melamine water-reducing agents, and naphthalene water-reducing agents.

6. The preparation method of a biomass air-entraining agent blended concrete according to claim 1, characterized in that, The foam stabilizer is selected from any one of sodium dodecyl sulfate, α-olefin sulfonate, sodium lauryl polyoxyethylene ether sulfate, dodecyldimethylamine oxide, and alkyl alkanolamide.

7. The preparation method of a biomass air-entraining agent blended concrete 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 preparation method of a biomass air-entraining agent blended concrete according to claim 1, characterized in that, The low-speed stirring evenly includes: Under the condition of a stirring speed of 65 - 85 r / min, continuously stir and mix for 15 - 25 min.

9. The preparation method of a biomass air-entraining agent blended concrete according to claim 8, wherein, The low-speed stirring evenly also includes: Under the condition of a stirring speed of 65 - 85 r / min, continuously stir and mix for 15 - 25 min, and maintain the temperature of the concrete slurry below 25 °C during the low-speed stirring process through cooling; Among them, the cooling is carried out by means of water cooling.

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