Liquid concrete hydrophobic permeability reducing agent as well as preparation method and application thereof

Abstract

The invention provides a liquid concrete hydrophobic permeability reducing agent which is characterized by comprising the following components in percentage by mass: 2-10% of an anti-seepage component, 10-30% of hydrophobic microcapsules, 0.3-0.8% of an air entraining component and the balance of water, wherein the impervious component comprises more than one of diethanol amine and triethanolamine, the hydrophobic microcapsule is formed by wrapping a water repellent on a porous chitosan shell, the porous chitosan shell is loaded with basophilic bacillus, the hydrophobic microcapsule exists in a suspension form, and the hydrophobic microcapsule is a hydrophobic microcapsule. The water repellent comprises more than one of silane, siloxane and fatty acid metal salt and exists in an emulsion form; the air entraining component comprises more than one of rosin ester polymer, sodium alkyl benzene sulfonate and triterpenoid saponin. According to the invention, the problems that the traditional water repellent is non-uniformly dispersed and is aggregated to the surface of aggregate to influence the impermeability and compressive strength are effectively solved, so that the concrete has dynamic pressure impermeability, static pressure hydrophobicity and crack self-repairing capability, and the waterproofness and durability of the concrete are improved.

Description

Technical Field

[0001] This invention belongs to the technical field of concrete waterproofing agent materials, specifically relating to a liquid concrete water-repellent and seepage-reducing agent, its preparation method, and its application. Background Technology

[0002] Concrete, as a major material in construction engineering, possesses excellent mechanical properties, but its non-homogeneous porous structure leads to problems of static pressure water absorption and dynamic pressure water seepage, which seriously affects the waterproofness and durability of concrete structures.

[0003] To address the issues of waterproofing and durability in concrete, concrete waterproofing materials have emerged. These materials are added during the concrete mixing process to improve the concrete's impermeability and water repellency, forming a simple and convenient process in one step. The impermeability-resistant components improve concrete density, thus enhancing its impermeability, while the water-repellent components increase its hydrophobicity, reducing its water absorption. However, due to their hydrophobic properties, water-repellent materials tend to accumulate on the aggregate surface during mixing, affecting the interfacial bond between the aggregate and the cementitious materials, thereby negatively impacting the concrete's impermeability and compressive strength. Therefore, improving the water repellency of concrete with water-repellent materials often sacrifices impermeability and compressive strength, affecting both waterproofing and durability.

[0004] Therefore, in order to improve the waterproofness and durability of concrete, there is still a need for a material that can simultaneously improve the static pressure water repellency and dynamic pressure impermeability of concrete. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a liquid concrete water-repellent and seepage-reducing agent, its preparation method, and its application, aiming to solve the problem of water-repellent agent enrichment on the aggregate surface affecting the impermeability and strength of concrete.

[0006] As one aspect of the present invention, a liquid concrete hydrophobic and seepage-reducing agent is provided, comprising, by weight, 2-10% of an anti-seepage component, 10-30% of hydrophobic microcapsules, 0.3-0.8% of an air-entraining component, and the balance being water; wherein the anti-seepage component comprises one or more of diethanolamine and triethanolamine, the hydrophobic microcapsules are porous chitosan shells encapsulating the hydrophobic agent, the porous chitosan shells are loaded with alkalophilic Bacillus, the hydrophobic microcapsules exist in suspension form, the hydrophobic agent comprises one or more of silane, siloxane, and fatty acid metal salts, and exists in emulsion form; the air-entraining component comprises one or more of rosin ester polymer, sodium alkylbenzene sulfonate, and triterpenoid saponins.

[0007] As a preferred embodiment of the liquid concrete water-repellent and seepage-reducing agent of the present invention, the method for preparing the water-repellent microcapsules includes:

[0008] 1) Dissolve chitosan powder in dilute acetic acid solution to form a chitosan-acetic acid solution with a concentration of 1-2%;

[0009] 2) Add a hydrophobic emulsion to the chitosan acetic acid solution obtained in step 1), disperse by ultrasonic emulsification, add a pore-forming agent and a crosslinking agent, and stir to obtain a mixture;

[0010] 3) The mixture obtained in step 2) is added dropwise to a sodium hydroxide solution, stirred to form gel microspheres, then filtered, washed, and freeze-dried to obtain porous chitosan powder coated with a hydrophobic agent; further, the stirring is low-speed stirring, for example, 300 r / min;

[0011] 4) Immerse the porous chitosan powder obtained in step 3) in the alkalophilic Bacillus bacterial solution, vacuum adsorb for 30-60 minutes, and obtain the precipitate after sterile filtration. Add 1.5-4 times the mass of deionized water to the precipitate, add a dispersant, and homogenize under high pressure to form a stable hydrophobic microcapsule suspension with a concentration of 20-40%.

[0012] As a preferred embodiment of the liquid concrete water-repellent and seepage-reducing agent of the present invention, the silane includes one or more of n-octyltriethoxysilane and isobutyltriethoxysilane; the siloxane includes one or more of polydimethylsiloxane and polymethyltriethoxysiloxane; and the fatty acid metal salt includes calcium stearate.

[0013] As a preferred embodiment of the liquid concrete water-repellent and seepage-reducing agent of the present invention, in step 2), the concentration of the water-repellent agent in the water-repellent agent emulsion is 30-50%; the volume ratio of the water-repellent agent emulsion to the chitosan acetic acid solution is 1:5-1:15.

[0014] As a preferred embodiment of the liquid concrete water-repellent and seepage-reducing agent of the present invention, in step 3), the concentration of sodium hydroxide is 0.8~1.2 mol / L, more preferably 0.9 mol / L, 1 mol / L, or 1.1 mol / L.

[0015] As a preferred embodiment of the liquid concrete water-repellent and seepage-reducing agent of the present invention, in step 4), the concentration of the alkalophilic Bacillus bacterial solution is 10. 8 CFU / mL.

[0016] As a preferred embodiment of the liquid concrete water-repellent and seepage-reducing agent of the present invention, in step 4), the mass-to-volume ratio of the porous chitosan powder to the alkalophilic Bacillus bacterial solution is 1:2~1:5 g / mL.

[0017] As a preferred embodiment of the liquid concrete water-repellent and seepage-reducing agent of the present invention, the water-repellent microcapsules have a particle size of 5-20 μm.

[0018] As a preferred embodiment of the liquid concrete water-repellent and seepage-reducing agent of the present invention, the loading amount of alkalophilic Bacillus on porous chitosan is 3×10⁻⁶. 7 ~8×10 7 CFU / g.

[0019] As a preferred embodiment of the liquid concrete water-repellent and seepage-reducing agent of the present invention, the mass ratio of diethanolamine to triethanolamine in the seepage-reducing component is 1:1 to 1:2. Diethanolamine and triethanolamine can further reduce the porosity of concrete by adjusting the balance between cement hydration rate and gel formation.

[0020] As a preferred embodiment of the liquid concrete water-repellent and seepage-reducing agent of the present invention, the air-entraining agent adjusts the air content in the concrete to 3-7%.

[0021] As a preferred embodiment of the liquid concrete water-repellent and seepage-reducing agent of the present invention, the air-entraining component needs to meet the requirement of a 2-hour foam settling rate ≤10%.

[0022] In another aspect of the present invention, a method for preparing the aforementioned liquid concrete water-repellent and seepage-reducing agent is provided, comprising the following steps:

[0023] 1) Dissolve chitosan powder in dilute acetic acid solution to form a chitosan-acetic acid solution with a concentration of 1-2%;

[0024] 2) Add a hydrophobic emulsion to the chitosan acetic acid solution obtained in step 1), ultrasonically emulsify and disperse, add a pore-forming agent and a crosslinking agent and stir to obtain a mixture;

[0025] 3) The mixture obtained in step 2) is added dropwise into a sodium hydroxide solution, stirred to form gel microspheres, then filtered, washed, and freeze-dried to obtain porous chitosan powder coated with a hydrophobic agent;

[0026] 4) Immerse the porous chitosan powder obtained in step 3) in the alkalophilic Bacillus bacterial solution, vacuum adsorb for 30-60 min, and obtain the precipitate after sterile filtration. Add 1.5-4 times the mass of deionized water to the precipitate, add a dispersant, and homogenize under high pressure to form a stable hydrophobic microcapsule suspension with a concentration of 20-40%.

[0027] 5) Add each component according to the above-mentioned composition ratio of the hydrophobic seepage reducing agent, mix and stir evenly to obtain the hydrophobic seepage reducing agent.

[0028] As another aspect of the present invention, an application of the aforementioned liquid concrete water-repellent and seepage-reducing agent is provided, wherein the dosage of the liquid concrete water-repellent and seepage-reducing agent in concrete is 0.2-2% of the cementitious material, the liquid concrete water-repellent and seepage-reducing agent is added last in the concrete mixture, and the mixing time is ≤3 minutes.

[0029] This invention creatively discovers that when water evaporates and oxygen concentration decreases inside concrete, aerobic bacteria loaded on hydrophobic microcapsules will carry the microcapsules directionally to the concrete surface layer. Upon reaching the oxygen-rich zone, the aerobic bacteria dissolve chitosan through respiration, allowing the hydrophobic agent to diffuse out and exert its hydrophobic effect. This migration of the hydrophobic agent can form a gradient hydrophobic layer within the concrete, enhancing its hydrophobic effect under static pressure. Furthermore, the calcium carbonate produced by the aerobic bacteria's metabolism can fill microcracks, and its biological activity endows the hydrophobic seepage-reducing agent with "self-healing" capabilities. Thus, the introduction of aerobic bacteria in this invention achieves an integrated "repair-hydrophobic" function, becoming a repair and waterproofing barrier. Based on the technical solution of this invention, the suitable loading amount of alkalophilic Bacillus on porous chitosan is 3 × 10⁻⁶. 7 ~8×10 7 CFU / g, and even further, it can be 3×10 7 4×10 7 5×10 7 6×10 7 7×10 7 8×10 7 An interval consisting of any value or any two values.

[0030] This invention creatively discovers that introducing air-entraining components can form microbubbles in concrete, thereby increasing the air content of the concrete, improving its workability and durability, and providing a certain migration space for aerobic bacteria within the concrete, thus enhancing the migration characteristics of hydrophobic microcapsules. Based on the technical solution of this invention, the suitable air-entraining component is 0.3~0.8%, and more specifically, it can be any value or a range of any two values ​​from 0.3%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 0.65%, 0.7%, 0.75%, to 0.8%. The air-entraining component can be one or more of rosin ester polymers, sodium alkylbenzene sulfonate, and triterpenoid saponins. More preferably, the air-entraining component satisfies a 2-hour foam settling rate ≤10%. After incorporating the air-entraining component into the concrete, the average particle size of the bubbles in the hardened concrete is 50-200 μm, which can prevent the decrease in impermeability caused by bubble collapse during the concrete hardening process, while simultaneously providing migration space for hydrophobic microcapsules.

[0031] In addition, the present invention uses a chitosan shell to support aerobic bacteria. On the one hand, chitosan can provide a survival carrier and nutrient substrate for the colonization and growth of aerobic bacteria, which is conducive to the colonization of aerobic bacteria. On the other hand, the colonization of aerobic bacteria on the microspheres can better achieve the degradation of chitosan microspheres under sufficient oxygen conditions, releasing hydrophobic agents and playing a hydrophobic role.

[0032] It should be noted that the porogen, crosslinking agent, and dispersant involved in this invention are all common reagents in the art. Those skilled in the art can expect that using the above-mentioned common reagents in the art can achieve the desired effects of this invention. For example, the porogen of this invention can be polyethylene glycol 4000, the crosslinking agent can be genipin, and the dispersant can be Tween 80. To improve dispersion stability, dispersing aids, such as xanthan gum, can also be added.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. This invention loads aerobic bacteria onto a porous chitosan shell, which actively migrate the water-repellent agent inside the concrete to the surface layer, effectively solving the problems of uneven dispersion and aggregation of traditional water-repellent agents on the aggregate surface, affecting impermeability and compressive strength.

[0035] 2. By introducing an air-entraining agent, this invention improves the workability and durability of concrete while providing a certain migration space for aerobic bacteria in the concrete, thereby enhancing the migration characteristics of hydrophobic microcapsules.

[0036] 3. The impermeable component of this invention improves the density of concrete and forms a dense layer; the hydrophobic microcapsules form a gradient hydrophobic layer in the concrete and their biological activity endows the concrete with self-healing ability for cracks. The impermeable component and the hydrophobic microcapsules together form a triple rigid waterproof structure of dynamic pressure impermeability, static pressure hydrophobicity and crack self-healing, thereby improving the waterproofness and durability of concrete. Detailed Implementation

[0037] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] In specific embodiments of the present invention, the water-repellent agent used is commercially available Wacker Chemie BS1802 type water-repellent emulsion with a solid content of 50% and a density of 0.95 g / cm³ at 25°C. 3 The aerobic bacteria are alkalophilic Bacillus, which are rod-shaped and have a width of 0.5 μm to 1.5 μm and a length of 1 μm to 5 μm. Alkaliophilic Bacillus requires oxygen for metabolism and can survive in an alkaline environment.

[0039] Example 1

[0040] A liquid concrete hydrophobic and seepage-reducing agent, by weight, comprises: 2% diethanolammonium, 3% triethanolammonium, 20% hydrophobic microcapsules, 0.4% sodium alkylbenzene sulfonate and 74.6% water.

[0041] The preparation method of the hydrophobic agent microcapsules includes the following steps:

[0042] 1) Dissolve 10g of chitosan powder in 1000mL of 2% dilute acetic acid solution to form a 1% chitosan acetic acid solution;

[0043] 2) Add 100 mL of hydrophobic emulsion to the chitosan acetic acid solution obtained in step 1), disperse by ultrasonic emulsification, add 1 g of polyethylene glycol 4000 porogen and 3 g of genipin crosslinking agent, and stir at 300 r / min for 1.5 h to obtain a mixture;

[0044] 3) The mixture obtained in step 2) was sprayed into a 1 mol / L sodium hydroxide solution using a sprayer, while the sodium hydroxide solution was stirred at a speed of 300 r / min to form 5-20 μm gel microspheres. The sodium hydroxide solution containing the gel microspheres was then filtered to collect the gel microspheres, washed three times with deionized water, and freeze-dried at -50℃ for 24 h to obtain porous chitosan powder coated with a hydrophobic agent.

[0045] 4) Immerse the porous chitosan powder obtained in step 3) in a Bacillus alkalophilus bacterial solution with a concentration of 10. 8 The mass-to-volume ratio of porous chitosan powder to alkalophilic Bacillus bacterial solution was 1:4 g / mL. The mixture was evacuated to -0.06 MPa and maintained for 30 min to allow alkalophilic Bacillus to adsorb onto the pores or surface of the porous chitosan. The adsorbed mixture was centrifuged at 4000 r / min for 5 min to collect the precipitate. Three times the mass of deionized water was added to the precipitate, followed by 0.5% of Tween 80 dispersant and 0.1% xanthan gum. The mixture was homogenized under high pressure at 50 MPa and cyclicated three times to form a stable hydrophobic microcapsule suspension.

[0046] Example 2

[0047] A liquid concrete hydrophobic and seepage-reducing agent, by mass, comprises: 2% diethanolammonium, 3% triethanolammonium, 10% hydrophobic microcapsules, 0.4% sodium alkylbenzene sulfonate and 84.6% water.

[0048] The preparation method of the hydrophobic agent microcapsules includes the following steps:

[0049] 1) Dissolve 10g of chitosan powder in 1000mL of 2% dilute acetic acid solution to form a 1% chitosan acetic acid solution;

[0050] 2) Add 100 mL of hydrophobic emulsion to the chitosan acetic acid solution obtained in step 1), disperse by ultrasonic emulsification, add 1 g of polyethylene glycol 4000 porogen and 3 g of genipin crosslinking agent, and stir at 300 r / min for 1.5 h to obtain a mixture;

[0051] 3) The mixture obtained in step 2) was sprayed into a 1 mol / L sodium hydroxide solution using a sprayer, while the sodium hydroxide solution was stirred at a speed of 300 r / min to form 5-20 μm gel microspheres. The sodium hydroxide solution containing the gel microspheres was then filtered to collect the gel microspheres, washed three times with deionized water, and freeze-dried at -50℃ for 24 h to obtain porous chitosan powder coated with a hydrophobic agent.

[0052] 4) Immerse the porous chitosan powder obtained in step 3) in a Bacillus alkalophilus bacterial solution with a concentration of 10. 8 The mass-to-volume ratio of porous chitosan powder to alkalophilic Bacillus bacterial solution was 1:4 g / mL. The mixture was evacuated to -0.06 MPa and maintained for 30 min to allow alkalophilic Bacillus to adsorb onto the pores or surface of the porous chitosan. The adsorbed mixture was centrifuged at 4000 r / min for 5 min to collect the precipitate. Three times the mass of deionized water was added to the precipitate, followed by 0.5% of Tween 80 dispersant and 0.1% xanthan gum. The mixture was homogenized under high pressure at 50 MPa and cyclicated three times to form a stable hydrophobic microcapsule suspension.

[0053] Example 3

[0054] A liquid concrete hydrophobic and seepage-reducing agent, by mass, comprises: 2% diethanolammonium, 3% triethanolammonium, 30% hydrophobic microcapsules, 0.4% sodium alkylbenzene sulfonate and 64.6% water.

[0055] The preparation method of the hydrophobic agent microcapsules includes the following steps:

[0056] 1) Dissolve 10g of chitosan powder in 1000mL of 2% dilute acetic acid solution to form a 1% chitosan acetic acid solution;

[0057] 2) Add 100 mL of hydrophobic emulsion to the chitosan acetic acid solution obtained in step 1), disperse by ultrasonic emulsification, add 1 g of polyethylene glycol 4000 porogen and 3 g of genipin crosslinking agent, and stir at 300 r / min for 1.5 h to obtain a mixture;

[0058] 3) The mixture obtained in step 2) was sprayed into a 1 mol / L sodium hydroxide solution using a sprayer, while the sodium hydroxide solution was stirred at a speed of 300 r / min to form 5-20 μm gel microspheres. The sodium hydroxide solution containing the gel microspheres was then filtered to collect the gel microspheres, washed three times with deionized water, and freeze-dried at -50℃ for 24 h to obtain porous chitosan powder coated with a hydrophobic agent.

[0059] 4) Immerse the porous chitosan powder obtained in step 3) in a Bacillus alkalophilus bacterial solution with a concentration of 10. 8 The mass-to-volume ratio of porous chitosan powder to alkalophilic Bacillus bacterial solution was 1:4 g / mL. The mixture was evacuated to -0.06 MPa and maintained for 30 min to allow alkalophilic Bacillus to adsorb onto the pores or surface of the porous chitosan. The adsorbed mixture was centrifuged at 4000 r / min for 5 min to collect the precipitate. Three times the mass of deionized water was added to the precipitate, followed by 0.5% of Tween 80 dispersant and 0.1% xanthan gum. The mixture was homogenized under high pressure at 50 MPa and cyclicated three times to form a stable hydrophobic microcapsule suspension.

[0060] Example 4

[0061] A liquid concrete hydrophobic and seepage-reducing agent, by weight, comprises: 2% diethanolammonium, 3% triethanolammonium, 20% hydrophobic microcapsules, 0.4% sodium alkylbenzene sulfonate and 74.6% water.

[0062] The preparation method of the hydrophobic agent microcapsules includes the following steps:

[0063] 1) Dissolve 10g of chitosan powder in 1000mL of 2% dilute acetic acid solution to form a 1% chitosan acetic acid solution;

[0064] 2) Add 75 mL of hydrophobic emulsion to the chitosan acetic acid solution obtained in step 1), emulsify and disperse using ultrasound, add 1 g of polyethylene glycol 4000 porogen and 3 g of genipin crosslinking agent, and stir at 300 r / min for 1.5 h to obtain a mixture;

[0065] 3) The mixture obtained in step 2) was sprayed into a 1 mol / L sodium hydroxide solution using a sprayer, while the sodium hydroxide solution was stirred at a speed of 300 r / min to form 5-20 μm gel microspheres. The sodium hydroxide solution containing the gel microspheres was then filtered to collect the gel microspheres, washed three times with deionized water, and freeze-dried at -50℃ for 24 h to obtain porous chitosan powder coated with a hydrophobic agent.

[0066] 4) Immerse the porous chitosan powder obtained in step 3) in a Bacillus alkalophilus bacterial solution with a concentration of 10. 8 The mass-to-volume ratio of porous chitosan powder to alkalophilic Bacillus bacterial solution was 1:4 g / mL. The mixture was evacuated to -0.06 MPa and maintained for 30 min to allow alkalophilic Bacillus to adsorb onto the pores or surface of the porous chitosan. The adsorbed mixture was centrifuged at 4000 r / min for 5 min to collect the precipitate. Three times the mass of deionized water was added to the precipitate, followed by 0.5% of Tween 80 dispersant and 0.1% xanthan gum. The mixture was homogenized under high pressure at 50 MPa and cyclicated three times to form a stable hydrophobic microcapsule suspension.

[0067] Example 5

[0068] A liquid concrete hydrophobic and seepage-reducing agent, by weight, comprises: 2% diethanolammonium, 3% triethanolammonium, 20% hydrophobic microcapsules, 0.4% sodium alkylbenzene sulfonate and 74.6% water.

[0069] The preparation method of the hydrophobic agent microcapsules includes the following steps:

[0070] 1) Dissolve 10g of chitosan powder in 1000mL of 2% dilute acetic acid solution to form a 1% chitosan acetic acid solution;

[0071] 2) Add 100 mL of hydrophobic emulsion to the chitosan acetic acid solution obtained in step 1), disperse by ultrasonic emulsification, add 1 g of polyethylene glycol 4000 porogen and 3 g of genipin crosslinking agent, and stir at 300 r / min for 1.5 h to obtain a mixture;

[0072] 3) The mixture obtained in step 2) was sprayed into a 1 mol / L sodium hydroxide solution using a sprayer, while the sodium hydroxide solution was stirred at a speed of 300 r / min to form 5-20 μm gel microspheres. The sodium hydroxide solution containing the gel microspheres was then filtered to collect the gel microspheres, washed three times with deionized water, and freeze-dried at -50℃ for 24 h to obtain porous chitosan powder coated with a hydrophobic agent.

[0073] 4) Immerse the porous chitosan powder obtained in step 3) in a Bacillus alkalophilus bacterial solution with a concentration of 10. 8The mass-to-volume ratio of porous chitosan powder to alkalophilic Bacillus bacterial solution was 1:2 g / mL. The mixture was evacuated to -0.06 MPa and maintained for 30 min to allow alkalophilic Bacillus to adsorb onto the pores or surface of the porous chitosan. The adsorbed mixture was centrifuged at 4000 r / min for 5 min to collect the precipitate. Three times the mass of deionized water was added to the precipitate, followed by 0.5% of Tween 80 dispersant and 0.1% xanthan gum. The mixture was homogenized under high pressure at 50 MPa and cyclicated three times to form a stable hydrophobic microcapsule suspension.

[0074] Comparative Example 1

[0075] A liquid concrete water-repellent and seepage-reducing agent, by weight, comprises: 2% diethanolammonium, 3% triethanolammonium, 0.4% sodium alkylbenzene sulfonate and 94.6% water, i.e., without the addition of water-repellent microcapsules.

[0076] Comparative Example 2

[0077] A liquid concrete water-repellent and seepage-reducing agent, by mass, comprises: 2% diethanolammonium, 3% triethanolammonium, 1% water-repellent emulsion, 0.4% sodium alkylbenzene sulfonate and 93.6% water, wherein the water-repellent emulsion is not coated with chitosan and is not loaded with aerobic bacteria.

[0078] Comparative Example 3

[0079] A liquid concrete hydrophobic and seepage-reducing agent, by weight, comprises: 20% hydrophobic microcapsules, 0.4% sodium alkylbenzene sulfonate, and 79.6% water, i.e., without the addition of anti-seepage components. The preparation method of the hydrophobic microcapsules is the same as in Example 1.

[0080] Comparative Example 4

[0081] A liquid concrete hydrophobic and seepage-reducing agent, by weight, comprises: 2% diethanolammonium, 3% triethanolammonium, 20% hydrophobic microcapsules, and 75% water, i.e., without the addition of air-entraining components. The preparation method of the hydrophobic microcapsules is the same as in Example 1.

[0082] Test Plan

[0083] 1) Hydrophobic microcapsule test

[0084] To test the loading capacity of alkalophilic aerobic bacteria in porous chitosan microcapsules, the loading capacity of alkalophilic Bacillus was calculated using the following formula: ,in, The initial bacterial concentration (CFU / mL) is given. The concentration of residual bacterial solution after immobilization (CFU / mL) is given. The volume of the bacterial culture is expressed in mL. The dry weight (g) of the carrier is given. The bacterial suspension concentration was determined using the OD method. Based on the direct proportionality between the bacterial suspension concentration and the optical density (OD) value, the OD value of the bacterial suspension was measured, and the bacterial suspension concentration was calculated using a standard curve.

[0085] Table 1 Loading capacity of alkalophilic Bacillus on porous chitosan

[0086]

[0087] 2) Concrete mix design

[0088] Concrete specimens were prepared using C30 grade concrete for testing. The test combinations for water absorption, compressive strength, cross-sectional contact angle, and crack self-healing of the concrete in the reference group, examples, and comparative examples are shown in Table 2. The test combinations for concrete impermeability are shown in Table 3. In the embodiments and comparative examples of this invention, the water-repellent and seepage-reducing agent was used at a dosage of 2% of the cement, replacing a portion of the mixing water.

[0089] Table 2. Mix proportions for concrete water absorption and compressive strength tests / kg

[0090]

[0091] Table 3 Mix proportions for concrete impermeability test / kg

[0092]

[0093] 3) Concrete performance testing

[0094] The slump of concrete was tested according to GB / T50080-2002 "Test Methods for Performance of Ordinary Concrete Mixtures"; the water absorption, compressive strength, and penetration height of concrete test blocks were tested according to standard JC / T474-2008 "Mortar and Concrete Waterproofing Agents". The self-healing performance of concrete cracks was tested according to standard TCECS913-2021 "Standard for Test Methods for Self-Healing Performance of Cement Concrete".

[0095] Concrete was molded according to the test mix proportions in Table 2. The concrete specimens were 100*100*100mm in size. The specimens were demolded 24 hours after molding and then cured to different ages according to standard conditions. The compressive strength and 28-day water absorption of the concrete specimens molded in the baseline group, Examples 1-5 of this invention, and Comparative Examples 1-4 were tested at different ages. Lower water absorption indicates better water repellency. The test results are shown in Table 4.

[0096] Table 4. Water absorption and compressive strength test results for the benchmark group, embodiments of the present invention, and comparative examples.

[0097]

[0098] Concrete was molded according to the mix proportions in Table 2. The concrete specimens were 150*150*150mm in size. The specimens were demolded 24 hours after molding and cured according to standard for 28 days. The specimens were then cut into two parts from the middle. A line was drawn along the middle of the side of each part, and five points were taken from one end to the other, for a total of ten points. The static contact angle at each point was measured. A larger contact angle indicates stronger hydrophobicity; a smaller contact angle indicates stronger hydrophilicity. The test results are shown in Table 5.

[0099] Table 5. Static contact angle detection table for cross-sections of the benchmark group, embodiments of the present invention, and comparative examples.

[0100]

[0101] According to the test ratio of precast concrete in Table 2, the concrete specimen size was φ100mm×50mm. The self-healing performance of concrete cracks was tested according to the standard TCECS913-2021 "Standard for Test Method of Self-Healing Performance of Cement Concrete". The initial water seepage rate was measured by splitting the crack after 7 days of curing, and the final water seepage rate was measured after 28 days of curing. The larger the crack self-healing capacity ratio, the better the crack self-healing performance. The test results are shown in Table 6.

[0102] Table 6 Crack Self-Healing Detection Table for the Benchmark Group, Embodiments of the Invention, and Comparative Examples

[0103]

[0104] According to the experimental ratio of the molded concrete in Table 3, the test block dimensions were a frustum of a cone with an upper diameter of 175 mm, a lower diameter of 185 mm, and a height of 150 mm. The permeability height of the test block at 28 days was tested; the lower the permeability height, the better the impermeability. The test results are shown in Table 7.

[0105] Table 7. Impermeability Test Tables for the Benchmark Group, Embodiments of the Invention, and Comparative Examples

[0106]

[0107] This invention relates to a liquid concrete water-repellent and seepage-reducing agent that is added during the concrete mixing process and mixed and molded simultaneously with the concrete, making it simple and convenient to use. Concrete containing this liquid concrete water-repellent and seepage-reducing agent exhibits low water absorption, good impermeability and compressive strength, and self-healing crack resistance. This liquid concrete water-repellent and seepage-reducing agent is suitable for waterproof concrete structures, especially for thinner concrete structures such as side walls, base slabs, or roof slabs.

[0108] It should be noted that, based on the above embodiments of the present invention, those skilled in the art can fully realize the scope of the independent claims and dependent claims of the present invention, and the implementation process and methods are the same as those in the above embodiments; and the parts of the present invention not described in detail belong to the well-known technology in the art. However, the protection scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

Claims

1. A liquid concrete water-repellent and seepage-reducing agent, characterized in that, By weight, the hydrophobic impermeable agent comprises 2-10% impermeable component, 10-30% hydrophobic microcapsules, 0.3-0.8% air-entraining component, and the balance being water; wherein, the impermeable component comprises one or more of diethanolamine and triethanolamine, the hydrophobic microcapsules are porous chitosan shells encapsulating the hydrophobic agent, the porous chitosan shells are loaded with alkalophilic Bacillus, the hydrophobic microcapsules exist in suspension form, the hydrophobic agent comprises one or more of silane, siloxane, and fatty acid metal salts, and exists in emulsion form; the air-entraining component comprises one or more of rosin ester polymer, sodium alkylbenzene sulfonate, and triterpenoid saponins.

2. A liquid concrete water-repellent and seepage-reducing agent as described in claim 1, characterized in that, The method for preparing the hydrophobic microcapsules includes: 1) Dissolve chitosan powder in dilute acetic acid solution to form a chitosan-acetic acid solution with a concentration of 1-2%; 2) Add a hydrophobic emulsion to the chitosan acetic acid solution obtained in step 1), disperse by ultrasonic emulsification, add a pore-forming agent and a crosslinking agent, and stir to obtain a mixture; 3) The mixture obtained in step 2) is added dropwise into a sodium hydroxide solution, stirred to form gel microspheres, then filtered, washed, and freeze-dried to obtain porous chitosan powder coated with a hydrophobic agent; 4) Immerse the porous chitosan powder obtained in step 3) in the alkalophilic Bacillus bacterial solution, vacuum adsorb for 30-60 minutes, and obtain the precipitate after sterile filtration. Add 1.5-4 times the mass of deionized water to the precipitate, add a dispersant, and homogenize under high pressure to form a stable hydrophobic microcapsule suspension with a concentration of 20-40%.

3. A liquid concrete water-repellent and seepage-reducing agent as described in claim 1 or 2, characterized in that, The silane includes one or more of n-octyltriethoxysilane and isobutyltriethoxysilane; the siloxane includes one or more of polydimethylsiloxane and polymethyltriethoxysiloxane; the fatty acid metal salt includes calcium stearate.

4. A liquid concrete water-repellent and seepage-reducing agent as described in claim 2, characterized in that, In step 2), the concentration of the hydrophobic agent in the hydrophobic agent emulsion is 30-50%; the volume ratio of the hydrophobic agent emulsion to the chitosan acetic acid solution is 1:5-1:

15.

5. A liquid concrete water-repellent and seepage-reducing agent as described in any one of claims 1 to 2 and 4, characterized in that, The hydrophobic microcapsules have a particle size of 5-20 μm.

6. A liquid concrete water-repellent and seepage-reducing agent as described in any one of claims 1 to 2 and 4, characterized in that, The loading of the alkalophilic Bacillus on porous chitosan was 3 × 10⁻⁶. 7 ~8×10 7 CFU / g.

7. A liquid concrete water-repellent and seepage-reducing agent as described in any one of claims 1 to 2 and 4, characterized in that, The mass ratio of diethanolamine to triethanolamine in the antipermeability component is 1:1 to 1:

2.

8. A liquid concrete water-repellent and seepage-reducing agent as described in any one of claims 1 to 2 and 4, characterized in that, The air-entraining component adjusts the air content of the concrete to 3-7%.

9. A method for preparing a liquid concrete water-repellent and seepage-reducing agent as described in any one of claims 1 to 8, characterized in that, Includes the following steps: 1) Dissolve chitosan powder in dilute acetic acid solution to form a chitosan-acetic acid solution with a concentration of 1-2%; 2) Add a hydrophobic emulsion to the chitosan acetic acid solution obtained in step 1), disperse by ultrasonic emulsification, add a pore-forming agent and a crosslinking agent, and stir to obtain a mixture; 3) The mixture obtained in step 2) is added dropwise to a 1 mol / L sodium hydroxide solution, stirred at low speed to form gel microspheres, then filtered, washed, and freeze-dried to obtain porous chitosan powder coated with a hydrophobic agent; 4) Immerse the porous chitosan powder obtained in step 3) in the alkalophilic Bacillus bacterial solution, vacuum adsorb for 30-60 min, and obtain the precipitate after sterile filtration. Add 1.5-4 times the mass of deionized water to the precipitate, add a dispersant, and homogenize under high pressure to form a stable hydrophobic microcapsule suspension with a concentration of 20-40%. 5) Add each component according to the component ratio of the hydrophobic seepage reducing agent as described in any one of claims 1 to 8, mix and stir evenly to obtain the hydrophobic seepage reducing agent.

10. An application of the liquid concrete water-repellent and seepage-reducing agent as described in any one of claims 1 to 8, characterized in that, The liquid concrete water-repellent and seepage-reducing agent is added to the concrete at a dosage of 0.2-2% of the cementitious material. The liquid concrete water-repellent and seepage-reducing agent is added last to the concrete mixture, and the mixing time is ≤3 minutes.

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