Disclosure of Invention
In order to overcome the technical and environmental protection defects of the foaming agent of the existing foam concrete, the invention provides a low-carbon foam concrete composite foaming agent and a preparation method thereof, in particular to a low-carbon and environmental protection composite foaming agent which is prepared by taking animal protein as main protein as mother liquor protein, taking the protein as a modification target, doping an ionic or nonionic surfactant to modify the mother liquor protein, and realizing the low-carbon and environmental protection targets.
In order to achieve the above purpose, the invention adopts the following technical scheme:
The foam concrete composite foaming agent comprises the following components in percentage by weight:
selecting Jili butyl powder as a base material to hydrolyze protein, wherein the mass fraction is 10%;
the alkaline protease is papain, and the mass fraction of the alkaline protease is 2.1%;
The surface active substance is sodium fatty ether polyoxyethylene alcohol sulfate (AES), and the mass fraction is 1-2%;
sodium caseinate (hereafter SCA) with mass fraction of 8-9%;
Deionized water is selected as the dissolving water, and the dissolving water accounts for the rest mass fraction.
The preparation method of the low-carbon foam concrete composite foaming agent comprises the steps of mother liquor protein preparation and surface active substance doping:
S1, taking 20 parts of animal protein and 4.2 parts of alkaline protease, fully dissolving in 175.8 parts of water, regulating the pH to be proper for the alkaline protease by using alkali, hydrolyzing at the hydrolysis temperature of 40-60 ℃ for at least 30min, adding acid to regulate the pH to be near neutral after the hydrolysis is completed, and cooling the solution for secondary filtration to obtain the protein;
Preferably, the animal protein is gemfibrozil flour;
Preferably, the hydrolysis temperature is 45 ℃;
Preferably, the alkali is an inorganic alkali solution with a concentration of 0.3mol/L, such as sodium hydroxide, calcium hydroxide and the like, preferably sodium hydroxide;
preferably, the acid is a dilute hydrochloric acid solution with a mass fraction of 5%;
Preferably, the alkaline protease is papain, and the pH range is 10-11;
Preferably, the protein stock solution is prepared by the following method:
Taking 20 parts of animal protein Jili Ding powder and 4.2 parts of papain, fully dissolving in 175.8 parts of water, regulating the pH value to be 10.86 by using a sodium hydroxide solution with the concentration of 0.3mol/L, keeping the temperature for 45 ℃ water bath for 30min, adding a dilute hydrochloric acid solution to regulate the pH value to about 7 after the hydrolysis is completed, and cooling the solution for secondary filtration.
S2, adding SCA into the mother liquor protein in batches, continuously stirring until the mass fraction of the SCA is not more than 2.5%, continuously adding the SCA after no obvious precipitation until the SCA is completely mixed, continuously stirring for 5min every 10min until the solution presents milky milk texture and no precipitate substances are considered to be the completion of the emulsification reaction, and slowly adding 1g of AES into the mother liquor protein in a single step for gradient to ensure the accurate control of the single addition amount until the mother liquor protein has no obvious precipitate substances, wherein the preparation of the foaming agent is considered to be completed.
Compared with the existing foaming agent for foam concrete, the low-carbon foam concrete composite foaming agent has the following beneficial effects:
1. the protein, the anionic surfactant, the cationic surfactant and the emulsifier have low cost and are harmless to people, so that the problems of high cost, toxicity to operators and the like of the existing foaming agents are avoided;
2. the composite foaming agent is liquid, other organic solvents with dangerous properties are not needed to be mixed, the whole preparation process is physically changed, harmful gas is not discharged, and the danger caused by the inhalation of the solid powdery foaming agent into a human body is avoided;
3. the composite foaming agent has fewer operation steps, optimized and reasonable process and is easy to be used for large-scale industrial production;
4. the composite foaming agent and the foam concrete slurry are uniformly mixed, the foam stability is good, the defoaming rate is low, and the compressive strength of the prepared new foam concrete product is 1.5-2 times of the same dry density grade under the industry standard.
5. The micro pore size distribution of the foam concrete prepared by the composite foaming agent is uniform and is within the range of 50-350 mu m, which is smaller than the pore size of the common foam concrete.
6. The density of the prepared liquid composite foaming agent is slightly higher than that of water, the relative volume weight is lower, and the transportation and the storage are convenient.
7. The prepared foam concrete is a low-carbon environment-friendly material and can be widely applied to major infrastructure construction such as road and bridge construction, filling engineering, underground geotechnical engineering, building energy-saving components, energy infrastructure construction, port hydraulic engineering, ocean engineering, military engineering, oilfield mine engineering and the like.
Detailed Description
The main raw materials and instruments required by the invention are as follows:
The foaming agent comprises the raw materials of Ji Liding% of base material hydrolyzed protein, 2.1% of alkaline protease, 1-2% of fatty ether polyoxyethylene alcohol sodium sulfate (AES), 8-9% of sodium caseinate, 1.9% of pH adjusting agent, and deionized water.
The cementing material for mixing the foam concrete is P.O 42.5.42 cement and I-grade fly ash, the cement mortar water reducer is a high-efficiency polycarboxylate water reducer, and the mixing water is purified water.
The device comprises a constant-temperature water bath, a single-shaft horizontal rail forced concrete mixer, a universal testing machine, a foam quality tester, a foam concrete foaming machine, a beaker, a test tube, pH test paper, a concrete standard mould and a concrete curing box.
The preparation method of the low-carbon foam concrete composite foaming agent mainly comprises the steps of mother liquor protein preparation and surface active substance doping:
S1, taking animal protein Jili butyl powder and papain, fully dissolving in water, adjusting the pH to 10-11 by using a sodium hydroxide solution with the concentration of 0.3mol/L, heating in a water bath with the constant temperature of 45 ℃ for 30min, cooling the solution, and carrying out secondary filtration.
S2, mixing SCA into mother liquor protein in batches of 4, continuously stirring, continuing to mix until SCA is completely mixed, continuously stirring for 5min every 10min until the solution presents milky milk texture and no precipitate substances, namely, the emulsification reaction is completed, and mixing AES into mother liquor protein in batches of 2-4 for ensuring accurate control of single mixing amount, wherein the single stirring time is not less than 5min until the mother liquor protein has no obvious precipitate substances, namely, the foaming agent is prepared.
Specific examples are as follows:
Example 1
The foaming agent comprises mother solution protein, sodium Caseinate (SCA), fatty alcohol polyoxyethylene ether sodium sulfate solution (AES), sodium hydroxide solution and deionized water.
Wherein, the mass fraction of the protein is 10%, the mass fraction of the Sodium Caseinate (SCA) is 8%, the mass fraction of the fatty alcohol polyoxyethylene ether sodium sulfate solution (AES) is 1%, and the mass fraction of the sodium hydroxide solution is 1.9% based on the total mass of the foaming agent.
Example 2
The foaming agent comprises mother solution protein, sodium Caseinate (SCA), fatty alcohol polyoxyethylene ether sodium sulfate solution (AES) and deionized water.
Wherein, the mass fraction of the protein is 10%, the mass fraction of the Sodium Caseinate (SCA) is 8%, the mass fraction of the fatty alcohol polyoxyethylene ether sodium sulfate solution (AES) is 2%, and the mass fraction of the sodium hydroxide solution is 1.9% based on the total mass of the foaming agent.
Example 3
The foaming agent comprises mother solution protein, sodium Caseinate (SCA), fatty alcohol polyoxyethylene ether sodium sulfate solution (AES) and deionized water.
Wherein, the mass fraction of the protein is 10%, the mass fraction of the Sodium Caseinate (SCA) is 9%, the mass fraction of the fatty alcohol polyoxyethylene ether sodium sulfate solution (AES) is 1%, and the mass fraction of the sodium hydroxide solution is 1.9% based on the total mass of the foaming agent.
The experimental results are shown in Table 1
TABLE 1 foam group Properties of composite foamer incorporating SCA and AES
| Group of | SCA blend/% | AES doping/% | Average 1h bleeding/mm | 1H bleeding Rate/% | Expansion ratio of foaming |
| Example 1 | 8 | 1 | 172 | 46.03 | 16.0 |
| Example 2 | 8 | 2 | 178 | 47.34 | 15.9 |
| Example 3 | 9 | 1 | 170 | 44.36 | 15.6 |
The foaming agent dilution factors of example 1, example 2 and example 3 were all 10 times. All three examples meet the requirement that the bleeding rate of 1h specified in the industry standard of foaming agents for foam concrete is not more than 70%.
Example 4 Low carbon foam concrete prepared by the foam concrete composite foaming agent of the invention, the concrete preparation method is as follows:
① The concrete mixer is adopted to meet the requirements of JG244-2009, the concrete mixer is specifically operated to pour water into a mixing drum, and cementing materials such as cement and the like are slowly added into the mixing drum within 5-10 seconds. Stopping stirring for 90s, stopping stirring for several seconds, scraping the cement paste on the blade and the wall of the pot into the pot, and stirring for 90s again to finally obtain clean paste;
② Foaming while preparing the clear slurry. And diluting the foaming agent according to a preset dilution ratio, and foaming by adopting an air compression foaming machine specified by a standard after uniformly stirring. When sampling, the foaming discharge port is arranged at the bottommost part of the container, and the container is filled with the foaming discharge port by utilizing impact pressure;
③ Mixing the stirring paste with the foam for 2min, standing for several seconds to clean the inner wall and the blades, stirring for 1min, and taking out all materials at one time;
④ And (3) after the casting mold is scraped, maintaining the curing box at room temperature for 28 days.
The present and subsequent examples each employ two foam concrete mix ratios as shown in table 2 below.
Table 21 m3 foam concrete formulation
| Numbering device | Cement/kg | Fly ash/kg | Water/kg | Water reducing agent/g | Foam/L |
| C0 | 642 | 275 | 321 | 550 | 439 |
| C1 | 561 | 241 | 321 | 550 | 439 |
1M3 foam concrete was prepared using any of the three examples described above, with foaming to 439L.
The experimental results are shown in FIG. 1
As shown in FIG. 1, the control group was a commercially available foaming agent for a foam concrete. Obviously, the increasing trend of the dry density-compressive strength change of the foam concrete prepared by the multiple re-mixed foaming agents is larger than that of the dry density-compressive strength curve set according to the specification and that of the dry density-compressive strength curve of the control group. Of the composite blowing agents in which SCA and AES are blended, example 3 has the greatest ratio of compressive strength to dry density, and has obvious specific strength advantage as a preferable component. The foam concrete of the embodiment has the advantages of uniform mixing of foam groups and concrete slurry, less natural defoaming, better air hole stability, uniform distribution, and dry density grade of A10-A11, and compressive strength which is more than 1.5 times of the compressive strength defined in the industry specification.
Example 5 microcosmic homogeneity characterization of Low carbon foam concrete made with the composite foaming agent of the invention
Foam concrete is prepared by adopting the foaming agents in the embodiment 1, the embodiment 2 and the embodiment 3, and microscopic homogeneity characterization is carried out on the foam concrete test block of the embodiment 3 with better performance in the embodiment by using an SEM (scanning electron microscope).
The distribution of microscopic pores and pore size were observed by magnification at 100 times.
The experimental results are shown in fig. 2a and 2b.
As in fig. 2a and 2b, the pore size distribution of the blowing agent is ordered regularly as control > examples. It can be seen that the foam of the foam population produced by the blowing agent of the present invention is relatively uniformly distributed. Although the foam of the example has weaker regularity of pore size distribution than the control group, the single pore size distribution is more ideal, and the pore size in the slurry is concentrated in a range of values. Specific minimum and maximum pore sizes were measured as shown in table 3.
TABLE 3 minimum and maximum pore sizes of 1m3 foam concrete formulations
| Group name | Minimum pore size/. Mu.m | Maximum pore size/. Mu.m |
| Examples | 72.73 | 200.23 |
| Control group | 49.89 | 325.41 |
The distribution of the microscopic hydration products and the surface active substances was observed by magnification at 10000 times.
The experimental results are shown in FIG. 3a and FIG. 3b
As shown in fig. 3a, 3b, the modified group of examples was observed to have a significant "integrity" in terms of bubble association compared to the control group. The control group at 10000 times showed no obvious association between the clusters of hydrated product and the apparent foam.
Example 6 characterization of micro-homogeneity of Low-carbon foam concrete prepared with the composite foaming agent of the invention
The foaming agents described in example 1, example 2 and example 3 of the present invention were used to prepare low-carbon foam concrete, and the curing sedimentation rate of the foam concrete slurry was measured.
The experimental results are shown in FIG. 4
As shown in fig. 4, the foaming agents described in example 1, example 2 and example 3 are used for preparing foam concrete, and the curing sedimentation rate of the foam concrete slurry is larger than that of the slurry of a control group, but is generally smaller than 8% specified in the industry specification, so that the performance index requirements of the low-carbon foam concrete are met.
Example 7 microcosmic chemical composition characterization and mechanism analysis of Low carbon foam concrete prepared according to the invention
The foaming agent is used for preparing foam concrete, and the XRD diffractometer is used for characterizing microscopic chemical components of a foam concrete test block with better performance and further performing mechanism analysis.
The XRD patterns of the foamed concrete prepared in example 1 showed a very narrow polymerization peak at about 2θ=18°,2θ=27°,2θ=30° and 2θ=34°, which represents the incorporation phenomenon of the composite cement-based crystalline material, and the XRD patterns of example 3 showed a very narrow polymerization peak at about 2θ=18°,2θ=27° and 2θ=34°, but the peak size was relatively small compared with the other three groups of peaks, indicating that the crystallinity of the compound at this position was significantly lower than that of example 1. In general, the C-S-H gel with more peaks in both groups of foam concrete shows that the crystals in the concrete have various configurations, and the foaming agent plays a positive role in the development of the strength of the foam concrete and energy conservation and carbon reduction.