A temperature-reducing anti-cracking concrete waterproofing agent and a preparation method thereof

Abstract

The application provides a temperature-controlling anti-cracking concrete waterproof agent and a preparation method thereof, characterized by comprising the following raw materials: siloxane dihydric alcohol, dihydroxy acid, diisocyanate, catalyst, diacylhydrazone chain extender and water; the molar ratio of the diisocyanate, the siloxane dihydric alcohol, the dihydroxy acid and the diacylhydrazone chain extender is (1.98-2.05):(0.2-0.8):(0.2-0.8):(1.05-1.2); the solid content of the waterproof agent is 20%-35%; the diacylhydrazone chain extender contains carbon-carbon double bond, disulfide bond and acylhydrazone bond self-repairing groups in the structure; the concrete waterproof agent provided by the application has excellent temperature control, anti-cracking and waterproof effects, can be applied to concrete or other building materials, can form a continuous and dense waterproof film on the surface of the concrete, effectively prevents water penetration, gives the concrete good flexibility, anti-cracking performance and temperature buffering effect, and can increase the cohesion and strength of the concrete through interaction, and can be applied to large engineering concrete to meet the waterproof requirements of high waterproof building fields such as underground engineering and hydraulic structures.

Description

Technical Field

[0001] This invention belongs to the field of concrete admixtures in building materials, and particularly relates to a temperature-suppressing, crack-resistant, and waterproof concrete agent and its preparation method. Background Technology

[0002] Concrete is a non-homogeneous material, brittle and prone to cracking. Its inherent properties, including the exothermic reaction during cement hydration and shrinkage, create conditions conducive to leakage in structures. Related research indicates that temperature cracks and the volumetric shrinkage during cement hydration are the main causes of cracking in concrete structures. From the moment concrete is poured, the cementitious material releases heat during hydration, undergoing a temperature rise phase, reaching a peak temperature, and then entering a temperature drop and shrinkage phase until it cools to ambient temperature. Concrete itself has poor thermal conductivity, so in large-volume concrete structures, a temperature gradient often exists where the internal temperature is high and the surface temperature is low. This creates tensile stress on the concrete surface, causing early-age deformation and cracking. Therefore, waterproofing is crucial to prevent cracking and seepage from affecting the stability and durability of building structures.

[0003] In large-volume, high-strength, and highly constrained concrete projects, there are two main methods for waterproofing concrete structures: one is to coat or lay a waterproof layer on the surface to prevent corrosion, but this has a short service life and requires frequent repairs; the other is to incorporate a waterproofing agent into the concrete, which can compensate for shrinkage during the cement setting and hardening process, generate prestress in the reinforcing steel, and fully fill the gaps between cement particles. Currently used waterproofing agents include inorganic chloride salts, sulfates, and water glass; and organic waterproofing agents include fatty acid metal salts and synthetic resins. The addition of these waterproofing agents to concrete can significantly affect its performance. For example, chloride ions accelerate the corrosion of reinforcing steel, and sulfate ions corrode the concrete matrix. Therefore, current waterproofing methods and agents have certain shortcomings. Thus, seeking a new type of waterproofing material that can comprehensively improve the waterproofing of concrete structures and reduce the risk of cracking by controlling temperature is an urgent need for the construction industry. Summary of the Invention

[0004] To address the above problems, this invention provides a temperature-suppressing, crack-resistant concrete waterproofing agent and its preparation method.

[0005] This invention relates to a temperature-inhibiting and crack-resistant concrete waterproofing agent, the raw materials of which include siloxane diol, dihydroxy acid, diisocyanate, catalyst, diacylhydrazone chain extender and water; the molar ratio of the diisocyanate, siloxane diol, dihydroxy acid and diacylhydrazone chain extender is (1.98~2.05):(0.2~0.8):(0.2~0.8):(1.05~1.2); the solid content of the waterproofing agent is 20%~35%;

[0006] The diacylhydrazone chain extender is synthesized by the following steps:

[0007] 1) Dithiol hydrocarbons undergo an exchange reaction with disulfur dichloride to generate intermediate 1;

[0008] 2) Intermediate 1 undergoes a substitution reaction with hydroxyenal to generate intermediate 2;

[0009] 3) Intermediate 2 reacts with alkyl diacid hydrazide via a Schiff base reaction to obtain a diacylhydrazone chain extender.

[0010] Further, the conditions for step 1) are as follows: Dithiol hydrocarbon and disulfur dichloride are reacted in a 1,4 dioxane medium with N-bromosuccinimide as a catalyst under sealed stirring for 2-4 hours; after the reaction is completed, the reaction mixture is concentrated under vacuum and then purified by silica gel chromatography to obtain intermediate 1.

[0011] The molar ratio of the dimercaptohydrocarbon, disulfide dichloride and N-bromosuccinimide is 1:(3.9-4.2):(1.0-1.2); the dimercaptohydrocarbon is a C1-C5 aliphatic hydrocarbon containing two terminal thiol groups, thiazide, benzene, biphenyl, naphthalene, diphenyl ether, or diphenyl sulfide.

[0012] Further, the conditions for step 2) are as follows: Under a nitrogen atmosphere, intermediate 1 and hydroxyenal are stirred in a dichloromethane, ethyl acetate, anhydrous ethanol, or acetone medium, with triethylamine as an acid-binding agent, in an ice bath at -5 to 5°C for 2 to 3 hours and in a water bath at 40 to 50°C for 6 to 12 hours. After the reaction is completed, the mixture is filtered, washed with saturated brine, acetone is removed by rotary evaporation under reduced pressure, and the mixture is concentrated and recrystallized to obtain intermediate 2.

[0013] The molar ratio of the hydroxyenal, intermediate 1 and triethylamine is 1:(1.1-1.5):(0.99-1.20); the hydroxyenal is an aldehyde compound containing at least one hydroxyl group and one carbon-carbon double bond.

[0014] Further, the conditions for step 3) are as follows: In anhydrous benzene, toluene, or ethanol medium, intermediate 2 and alkyl diacid hydrazide are heated under reflux in an oil bath at 50–60°C for 6–9 h with acetic acid as a catalyst; after the reaction is completed, the mixture is filtered through a Buchner funnel, the solvent is removed by rotary evaporation, the product is concentrated, and then sealed and stored at low temperature under argon gas. The molar ratio of intermediate 2, alkyl diacid hydrazide, and acetic acid is 1:(2–2.2):(0.8–1.0); the alkyl diacid hydrazide is selected from one or more of C3–C12 aliphatic hydrocarbon diacid hydrazides, phthalic acid diacid hydrazides, isophthalic acid diacid hydrazides, and terephthalic acid diacid hydrazides.

[0015] Furthermore, the siloxane diol is a siloxane substance containing two hydroxyl groups; representative examples include 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane, (1,1,3,3-tetramethyl-1,3-disiloxanediyl)diethanol, 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane, α-[3-[1,3,3,3-tetramethyl-1-(trimethylsilyl-oxo)disiloxane]-propyl-ω-hydroxypolyoxyethylene), and dihydroxyethoxypropyl-terminated polydimethylsiloxane.

[0016] The dihydroxy acid is a mono- or dicarboxylic acid containing two hydroxyl groups; representative examples include: 2,2-dimethylolpropionic acid, 2,2-dimethylolbutyric acid, 3,4-dihydroxybutyric acid, ketomalonic acid, glyceric acid, tartaric acid, dihydroxybenzoic acid, dihydroxyphenylacetic acid, 3,5-dihydroxy-4-methylbenzoic acid, 4,6-dihydroxyisophthalic acid, caffeic acid, 2,4-dihydroxycinnamic acid, and 3,4-dihydroxycinnamic acid.

[0017] Furthermore, the catalyst is added in an amount of 0.5% to 1.2% of the total mass of the system, and is selected from one or more of dibutyltin dilaurate (DBTDL), hexamethylenediamine (TEDA), N-alkyldiamine, N-alkylmorpholine, stannous octoate, zinc bismuth composite catalyst, bismuth isooctanoate, organozinc, and zinc neocaprate.

[0018] Further, the diisocyanate is one of 4-toluene diisocyanate, trans-1,4-cyclohexyl diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, dicyclohexylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,6-hexane diisocyanate, and lysine diisocyanate.

[0019] On the other hand, the present invention provides a method for preparing a temperature-suppressing and crack-resistant concrete waterproofing agent, comprising the following steps:

[0020] Dihydroxy acid and siloxane diol were pretreated by vacuum dehydration and drying at 120°C. Then, under a nitrogen atmosphere, the dihydroxy acid and siloxane diol were added to a four-necked flask equipped with a mechanical stirrer, reflux condenser, thermometer, and constant-pressure dropping funnel, and stirred at room temperature. The temperature was gradually increased to 60–70°C, and a mixture of diisocyanate and catalyst was added dropwise at 500–700 rpm. After the addition was completed, stirring was continued at 60–70°C for 1–2 hours. An aprotic solvent was added to adjust the viscosity of the system, and the temperature was increased to 90–120°C and stirred at a constant temperature for 5–9 hours. The system temperature was lowered to 40–60°C, and a diacylhydrazone chain extender was added, followed by stirring at a constant temperature for 3–4 hours. A neutralizing agent was added until the pH of the system reached 7.0–7.5, and the mixture was stirred for 30 minutes. Deionized water was added and stirred at high speed at 1000–1500 rpm for 30 minutes to emulsify and disperse the mixture. Residual aprotic solvent was removed by rotary evaporation to obtain a polyurethane emulsion-type waterproofing agent.

[0021] Furthermore, the aprotic solvent is one or more of butanone, dioxane, dimethylformamide, benzene, and toluene; the neutralizing agent is one of NH4OH, NaOH, monoethylamine, diethylamine, triethylamine, and triethanolamine.

[0022] This invention also provides the application of the above-mentioned temperature-suppressing and crack-resistant concrete waterproofing agent in the preparation of concrete.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] In terms of crack resistance and self-healing ability, the temperature-suppressing and crack-resistant concrete waterproofing agent provided by this technical solution has high symmetry and good three-dimensional regularity, and is easy to arrange into a highly ordered structure; its polymer structure contains dynamic groups such as carbon-carbon double bonds, disulfide bonds and hydrazone bonds, which makes the molecular chain further exhibit good elasticity and flexibility; when the material has micro-cracks, it can participate in reversible dynamic covalent bond reactions, so that the molecular chain segments rearrange and combine, and self-repair the cracks or damage.

[0025] Regarding temperature suppression, in concrete waterproofing agents, disulfide bonds and acylhydrazone groups possess energy absorption characteristics. Their reverse fracture or dissociation processes during temperature increases can absorb heat from the environment, acting as a temperature buffer and preventing stress concentration caused by temperature changes. Furthermore, they can form hydrogen bonds with cement hydration products and minerals in concrete, thereby increasing the cohesion of the concrete and making the material more structurally stable under temperature changes. Meanwhile, carbon-carbon double bonds can undergo cross-linking reactions at high temperatures to form a tight three-dimensional network structure, restricting the movement of molecular chains and thus reducing heat accumulation caused by intensified molecular chain movement.

[0026] Regarding waterproofing capabilities, the concrete waterproofing agent provided by this invention can form a continuous and dense waterproof membrane on the surface of concrete or other building materials, effectively preventing moisture penetration. During the drying and film-forming process of the waterproofing agent, acylhydrazone bonds, disulfide bonds, and silanyl groups can chemically bond with concrete raw materials to form a composite waterproofing system; the presence of double bonds can adjust the flexibility and hardness of the polymer, better adapting to the deformation of the base material while maintaining the integrity of the waterproof membrane.

[0027] The present invention features a simple and easy-to-operate preparation route from the synthesis of diacylhydrazone chain extender to concrete waterproofing agent, with mild reaction and abundant raw materials. Attached Figure Description

[0028] Figure 1 Preparation process of diacylhydrazone chain extender 1 in Preparation Example 1.

[0029] Figure 2 Preparation process of diacylhydrazone chain extender 2 in Preparation Example 2.

[0030] Figure 3 Preparation process of diacylhydrazone chain extender 3 in Preparation Example 3.

[0031] Figure 4 The 1H NMR spectrum of the diacylhydrazone chain extender 1 obtained in Preparation Example 1.

[0032] Figure 5 The 1H NMR spectrum of the diacylhydrazone chain extender 2 obtained in Preparation Example 2.

[0033] Figure 6 The 1H NMR spectrum of the diacylhydrazone chain extender 3 obtained in Preparation Example 3. Detailed Implementation

[0034] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. These embodiments are implemented based on the technical solution of the invention, providing detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments. Contents not described in detail in this specification are well-known to those skilled in the art.

[0035] Unless otherwise defined, the experimental materials used in the following examples and comparative examples are all available from conventional biochemical reagent companies.

[0036] Preparation Example 1

[0037] according to Figure 1 The process shown is used to synthesize diacylhydrazone chain extender 1:

[0038] 1) In a 100 mL reaction tube, 0.02 mol of ethylene glycol dimercaptoacetate and 0.02 mol of N-bromosuccinimide (C4H4BrNO2, abbreviated as NBS) dissolved in 64 mL of 1,4-dioxane were added, followed by the addition of 0.04 mol of disulfide dichloride. The tube was sealed, and the mixture was stirred at room temperature for 3 h. After the reaction was completed, the reaction mixture was concentrated under vacuum and purified by flash chromatography on silica gel to give intermediate 1 in 91.8% yield.

[0039] 2) Dissolve 0.08 mol of 3-allyl-2-hydroxybenzaldehyde and 0.09 mol of triethylamine (TEA) in 60 mL of dichloromethane. Slowly add a 40 mL dichloromethane solution containing 0.09 mol of intermediate 1 under a nitrogen atmosphere at 0 °C. Stir the mixture in an ice bath for 2 h, then reflux in a 40 °C water bath for 10 h. After the reaction, filter the solution. Wash the filtrate repeatedly with saturated brine until neutral. Remove the dichloromethane by rotary evaporation. Concentrate and recrystallize to obtain intermediate 2, with a yield of 82.5%.

[0040] 3) Prepare 100 mL of anhydrous ethanol solution containing 0.12 mol succinic dihydrazide and 40 mL of anhydrous ethanol solution containing 0.062 mol intermediate 2, and mix them. After adding 0.5 mol acetic acid (AcOH) catalyst, heat the mixture under reflux in an oil bath at 50 °C for 7.5 h. After the solution gradually cools and crystallizes, filter, wash three times with acetone, and then vacuum dry. Recrystallize again with anhydrous ethanol at 0–5 °C, filter, and vacuum dry to obtain diacylhydrazone chain extender 1 with a yield of 88.6%. Store under inert gas at low temperature. Diacylhydrazone chain extender 1 has the following structure:

[0041]

[0042] Preparation Example 2

[0043] according to Figure 2 The process shown is used to synthesize diacylhydrazone chain extender 2:

[0044] 1) In a 100 mL reaction tube, 0.02 mol of 1,4-dithiaran-2,5-di(methanethiol) and 0.02 mol of N-bromosuccinimide dissolved in 64 mL of 1,4-dioxane were added, followed by the addition of 0.04 mol of disulfide dichloride. The tube was sealed, and the mixture was stirred at room temperature for 2 h. After the reaction was complete, the reaction mixture was concentrated under vacuum and purified by silica gel chromatography to give intermediate 1, with a yield of 92.2%.

[0045] 2) Dissolve 0.075 mol of 3-(4-hydroxyphenyl)propenal and 0.08 mol of triethylamine in 60 mL of acetone. Slowly add 40 mL of acetone ester solution containing 0.09 mol of intermediate 1 under a nitrogen atmosphere at 0 °C. Stir the mixture in an ice bath for 2 h and reflux at 50 °C for 10 h. After the reaction, filter the solution, wash the filtrate with saturated brine, concentrate and recrystallize to obtain intermediate 2, with a yield of 83.3%.

[0046] 3) Prepare 100 mL of a toluene solution containing 0.12 mol of terephthalic acid dihydrazide and 40 mL of a toluene solution containing 0.062 mol of intermediate product 2, and mix them. After adding 0.5 mol of acetic acid catalyst, heat the mixture under reflux in an oil bath at 55 °C for 8.5 h. After the solution gradually cools and crystallizes, filter, wash three times with acetone, and then vacuum dry. Recrystallize again with anhydrous ethanol at 0–5 °C, filter, and vacuum dry to obtain diacylhydrazone chain extender 2 with a yield of 88.4%. Store under inert gas at low temperature. Diacylhydrazone chain extender 2 has the following structure:

[0047]

[0048] Preparation Example 3

[0049] according to Figure 3 The process shown is used to synthesize diacylhydrazone chain extender 3:

[0050] 1) In a 100 mL reaction tube, 0.02 mol of 4',4-dimercaptodiphenyl sulfide and 0.02 mol of N-bromosuccinimide dissolved in 64 mL of 1,4-dioxane were added, followed by the addition of 0.04 mol of disulfide dichloride. The tube was sealed, and the mixture was stirred at room temperature for 2.5 h. After the reaction was complete, the reaction mixture was concentrated under vacuum and purified by silica gel chromatography to give intermediate 1, with a yield of 93.5%.

[0051] 2) Dissolve 0.06 mol of 2-hydroxycinnamaldehyde and 0.066 mol of triethylamine in 60 mL of ethyl acetate. Slowly add 40 mL of ethyl acetate solution containing 0.067 mol of intermediate 1 under a nitrogen atmosphere at 0 °C. Stir the mixture in an ice bath for 2 h and reflux at 45 °C for 6 h. After the reaction, filter the solution, wash the filtrate with saturated brine, concentrate and recrystallize to give intermediate 2 in 84.8% yield.

[0052] 3) Prepare 100 mL of anhydrous benzene solution containing 0.12 mol malonyl hydrazide and 40 mL of anhydrous benzene solution containing 0.062 mol intermediate 2, and mix them. Add 0.5 mol acetic acid, and heat the mixture under reflux in an oil bath at 50 °C for 6 h. After the solution gradually cools and crystallizes, filter, wash three times with acetone, and then vacuum dry. Recrystallize again with anhydrous ethanol at 0–5 °C, filter, and vacuum dry to obtain diacylhydrazone chain extender 3, with a yield of 89.7%. Store under inert gas at low temperature. Diacylhydrazone chain extender 3 has the following structure:

[0053]

[0054] The molecular weights of diacylhydrazone chain extenders 1–3 were determined using a Waters 1515 / 2414 gel permeation chromatograph, and the degrees of polymerization were calculated. The results are shown in Table 1.

[0055] Table 1

[0056] sample Molecular weight (g / mol) PDI m Preparation Example 1 5188 1.72 7 Preparation Example 2 5052 1.69 7 Preparation Example 3 5054 1.75 7

[0057] As shown in Table 1, the molecular weights of the three diacylhydrazone chain extenders are similar, which demonstrates the universality of the preparation of the diacylhydrazone chain extenders of the present invention. The significant difference between the three diacylhydrazone chain extenders lies in whether the carbon-carbon double bond on the carbon chain of the polyurethane polymer is located in the main chain or the side chain.

[0058] The samples were analyzed using a Bruker spectrometer (Bruker, Coventrv) at 400 MHz. 50 mg of sample was weighed and placed in an NMR tube, 0.6 mL of LCDCl3 was added, and the sample was scanned 16 times. TMS localization was used for spectral processing. The 1H NMR spectra of diacylhydrazone chain extenders 1–3 are shown below. Figures 4-6 .

[0059] diacylhydrazone chain extender 1 1 H NMR: δ10.55 (s, 2H), 8.29 (s, 2H), 8.01 (t, 2H, J = 3.33Hz), 7.57 (d, 2H, J = 5.92Hz), 7.18 (dq, 2H, J = 6. 09,0.86Hz),7.08(t,2H,J=6.0Hz),5.89(ddd,,2H,J=18.98,13.56,10.67,5.39Hz),5.01(dq,4H,J =13.85,4.05Hz),4.44(s,4H),3.81(s,4H),3.65(d,2H,J=3.31Hz),3.37(dq,4H,J=5.26,0.71Hz), 2.37(t,4H,J=6.21Hz), 2.04(t,4H,J=6.61Hz), 1.68(ddd,4H,J=12.28,6.14,0.85Hz), 1.58(m,4H).

[0060] diacylhydrazone chain extender 2 1 H NMR: δ11.20(s,2H),9.08(t,2H,J=3.31Hz),8.17(dd,2H,J=6.28,1.50Hz),7.96( s,8H),7.47(dq,4H,J=6.30,1.27Hz),7.09(dq,2H,J=12.17,0.67Hz),7.06(dt,4 H,J=6.38,1.34Hz),6.99(q,2H,J=6.40Hz),4.10(d,4H,J=3.42Hz),3.30(m,2H,J =5.03, 2.51Hz), 3.13 (d, 4H, J = 2.34Hz), 2.85 (ddd, 4H, J = 12.61, 10.00, 2.61Hz).

[0061] Diacylhydrazone chain extender 3 1 H NMR: δ10.80 (s, 2H), 8.84 (t, 2H, J = 3.18Hz), 8.11 (dd, 2H, J = 6.22, 0.93Hz), 7. 53(dt,2H,J=6.29,0.57Hz),7.46(s,4H),7.27(td,2H,J=5.20,1.08Hz),7.09 (dt,2H,J=7.56,1.17Hz),7.07(dd,2H,J=7.62,1.17Hz),7.05(td,2H,J=7.58 ,1.17Hz), 6.78(dd,2H,J=8.07,6.48Hz), 3.85(d,4H,J=3.35Hz), 3.16(s,4H).

[0062] Example 1

[0063] A temperature-inhibiting and crack-resistant concrete waterproofing agent, the preparation steps of which are as follows:

[0064] Protocatechuic acid and 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane raw material were subjected to vacuum dehydration and drying pretreatment at 120°C.

[0065] Under a nitrogen atmosphere, 0.02 mol of protocatechuic acid and 0.02 mol of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane were added to a four-necked flask equipped with a mechanical stirrer, reflux condenser, thermometer, and constant-pressure dropping funnel, and stirred at room temperature. The mixture was then gradually heated to 70°C, and 0.08 mol of MDI and 0.23 g of [unspecified ingredient] were added dropwise while stirring at 600 rpm. DBTDL mixture; after the addition is completed, continue stirring at 70℃ for 1 hour; add 15 mL of methyl ethyl ketone to adjust the viscosity of the system, heat to 100℃ and stir at a constant temperature for 7 hours; lower the system temperature to 50℃, add 0.045 mol of diacylhydrazone chain extender 1, and stir at a constant temperature for 4 hours; add 0.025 mol of triethylamine until the pH of the system is 7.0 and stir for 30 minutes, add 171 g of deionized water and stir at 1000 rpm for 30 minutes to emulsify and disperse; remove the residual methyl ethyl ketone by rotary evaporation to obtain a polyurethane emulsion-type waterproofing agent with a solid content of 28%.

[0066] Example 2-3

[0067] A temperature-suppressing and crack-resistant concrete waterproofing agent differs from Example 1 in that the chain extenders used are diacylhydrazone chain extender 2 and diacylhydrazone chain extender 3, and to ensure that its solid content is similar to that of Example 1, the mass of deionized water added during emulsification is 176g and 154g respectively. Other raw materials and preparation process are the same as in Example 1.

[0068] Example 4

[0069] A temperature-suppressing and crack-resistant concrete waterproofing agent is used, in which the dihydroxy acid is caffeic acid and the diisocyanate is 2,6-diisocyanate toluene. In order to ensure that its solid content is similar to that of Example 1, the mass of deionized water added during emulsification is 157g. The remaining raw materials and preparation are the same as in Example 1.

[0070] Example 5

[0071] A temperature-suppressing and crack-resistant concrete waterproofing agent is used in which the dihydroxy acid is glyceric acid and the diisocyanate is cyclohexane-1,4-diisocyanate. In order to ensure that its solid content is similar to that of Example 1, the mass of deionized water added during emulsification is 154g. The remaining raw materials and preparation are the same as in Example 1.

[0072] Example 6

[0073] A temperature-suppressing and crack-resistant concrete waterproofing agent is used in which the siloxane diol is 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane, and in order to ensure that its solid content is similar to that of Example 1, the mass of deionized water added during emulsification is 175g, and the remaining raw materials and preparation are the same as in Example 1.

[0074] Example 7

[0075] A temperature-suppressing, crack-resistant concrete waterproofing agent.

[0076] Under a nitrogen atmosphere, 0.032 mol of protocatechuic acid and 0.008 mol of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane were added to a four-necked flask equipped with a mechanical stirrer, reflux condenser, thermometer, and constant-pressure dropping funnel, and stirred at room temperature. The mixture was then gradually heated to 70°C, and 0.08 mol of MDI and 0.23 g of [unspecified ingredient] were added dropwise while stirring at 600 rpm. A mixture of N-methylmorpholine was added; the mixture was stirred at 70°C for 1 hour after the addition was completed; 15 mL of butanone was added to adjust the viscosity of the system, and the temperature was raised to 100°C and stirred for 7 hours; the system temperature was lowered to 50°C, 0.045 mol of diacylhydrazone chain extender 1 was added, and the mixture was stirred at a constant temperature for 4 hours; 0.032 mol of triethylamine was added until the pH of the system was 7.0 and stirred for 30 minutes; 167 g of deionized water was added and stirred at 1000 rpm for 30 minutes to emulsify and disperse; residual butanone was removed by rotary evaporation to obtain a polyurethane emulsion-type waterproofing agent with a solid content of 28%.

[0077] Example 8

[0078] A temperature-suppressing, crack-resistant concrete waterproofing agent.

[0079] Under a nitrogen atmosphere, 0.008 mol of pre-vacuum-dried protocatechuic acid and 0.032 mol of 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane were added to a four-necked flask equipped with a mechanical stirrer, reflux condenser, thermometer, and constant-pressure dropping funnel, and stirred at room temperature. The mixture was then gradually heated to 70°C, and 0.08 mol of MDI and 0.23 g of [unspecified ingredient] were added dropwise while stirring at 600 rpm. TEDA mixture; after the addition is completed, continue stirring at 70℃ for 1h; add 15mL of methyl ethyl ketone to adjust the viscosity of the system, heat to 100℃ and stir at a constant temperature for 7h; lower the system temperature to 50℃, add 0.045mol of diacylhydrazone chain extender 1, and stir at a constant temperature for 4h; add 0.01mol of triethylamine to bring the pH of the system to 7.0 and stir for 30min, add 157g of deionized water and stir at 1000rpm for 30min to emulsify and disperse; remove residual methyl ethyl ketone by rotary evaporation to obtain a polyurethane emulsion-type waterproofing agent with a solid content of 28%.

[0080] Examples 9-10

[0081] A temperature-suppressing and crack-resistant concrete waterproofing agent differs from the example in that the mass of deionized water used is changed to 268g and 123g respectively, resulting in concrete waterproofing agent products with solid content of 20% and 35% respectively.

[0082] Comparative Examples 1-3

[0083] A concrete waterproofing agent, the difference being that the chain extenders used are succinic dihydrazide, terephthalic dihydrazide and malonic dihydrazide. In order to ensure that its solid content is similar to that of Example 1, the mass of deionized water added during emulsification is 86g, 92g and 85g respectively. The amount of other raw materials and the preparation process are the same as in Example 1.

[0084] Comparative Example 4

[0085] A concrete waterproofing agent, whose raw material dosage and preparation process are the same as in Example 1, except that 1,3-bis(3-hydroxypropyl)-1,1,3,3-tetramethyldisiloxane is not added, the dosage of protocatechuic acid is increased to 0.04 mol, and the dosage of triethylamine for neutralization is increased to 0.04 mol; and in order to ensure that its solid content is similar to that in Example 1, the mass of deionized water added during emulsification is 166 g, and other conditions remain unchanged.

[0086] Application example: Preparation of concrete with the above-mentioned temperature-inhibiting and crack-resistant waterproofing agent.

[0087] The temperature-inhibiting and crack-resistant concrete waterproofing agents of all the above embodiments and comparative examples were diluted with water and added to the concrete mix at 2% of the cement weight to prepare concrete test block samples. A blank group (reference test block sample) was also arranged. In addition, the concrete raw materials also included: 180 parts cement, 80 parts mineral powder, 100 parts fly ash, 800 parts river sand, 1000 parts crushed stone, 190 parts mixing water, and 10 parts polycarboxylate high-efficiency water-reducing agent. Among them, the cement was Huaren P·O 42.5 silicate cement; the fine aggregate was continuous graded medium sand with a fineness modulus of 3.0-2.3 and a mud content of ≤0.5%, produced by Macheng Chuhe Sand and Gravel State-owned Management Co., Ltd.; the coarse aggregate was water-washed and dried 5-20mm continuously graded Class I building crushed stone with a mud content of ≤0.5%, produced by Xianning Xian'an District Xinxin Mining Co., Ltd.; the fly ash was Class F Class I power plant fly ash with a specific surface area of ​​450m². 2 / kg, Wuhan Lianhekang Biotechnology Co., Ltd.; S95 mineral powder, specific surface area 480m² 2 / kg, density is 2.68g / cm³ 3 Lingshou County Defa Mineral Products Processing Plant; Polycarboxylate High-Efficiency Water Reducing Agent, with an air content of 5%, a water bleeding rate of 45%, and a water reduction rate of 28%, Hubei Guiyi New Building Materials Co., Ltd.

[0088] The concrete samples prepared for each application example were tested:

[0089] Semi-adiabatic temperature rise test: Concrete specimens were placed in a temperature measuring device within 10 minutes of adding water and mixing, and then placed in a constant temperature test chamber at 20±2℃. The temperature changes of the concrete specimens and the ambient temperature were recorded at a frequency of once every 10 minutes using a temperature sensor. After the peak temperature rise was measured, a cooling phase was initiated, and temperature measurement was stopped after 24 hours. The time required for each concrete specimen sample and the control group to reach a 5℃ temperature rise from the end of water addition and mixing, as well as the peak temperature, were recorded. The temperature suppression rate was calculated by comparing the peak temperature of the concrete specimen samples in the example with that of the control group.

[0090] 48-hour water absorption ratio and permeability height ratio: Both were tested according to standard GB / T 50082-2009 "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete". Water absorption ratio = 48-hour water absorption of concrete specimen sample / 48-hour water absorption of blank group. The 48-hour water absorption of the blank group was 1235 g / m³. 2 The permeability height ratio = permeability height of the concrete specimen / permeability height of the control group; the impermeability pressure used was 1.6 MPa, constant pressure for 24 hours; the impermeability height of the control group was 80.4 mm. The water absorption ratio mainly reflects the water absorption capacity of concrete in a static water environment, while the permeability height ratio reflects the permeability of concrete under pressurized water. These two properties together demonstrate the impermeability of the concrete.

[0091] The compressive strength of the concrete specimens was obtained by testing according to the provisions of the national standard GB / T50081-2002 "Standard for Test Methods of Mechanical Properties of Ordinary Concrete". The ratio of the compressive strength of the specimens to that of the blank group is called the compressive strength ratio. The compressive strengths of the blank group were 23.6 MPa (7 days) and 34.4 MPa (28 days).

[0092] The test results are shown in Table 2.

[0093] Table 2

[0094]

[0095] As can be seen from the various embodiments, the temperature-suppressing and crack-resistant waterproofing agent of the present invention has good waterproofing performance. The water absorption ratio after 48 days is less than 40%, and the penetration height ratio is not greater than 30%, which meets the requirements of the first-class product of the national standard JC / T474-2008. The compressive strength ratio meets the requirements of the qualified product of the national standard JC / T474-2008. The temperature suppression rate is increased to 47% to 57.5%, which meets the performance index requirements of the group standard T / CECS10270-2023.

[0096] Examples 1-3 demonstrate the improvement in temperature suppression and crack resistance of concrete achieved by introducing carbon-carbon double bond groups into the waterproofing agent. Whether located in the main chain (Examples 2-3) or side chain (Example 1) of the polyurethane polymer carbon chain, the carbon-carbon double bond exhibits a certain degree of reactivity. Through cross-linking reactions, it forms a dense network structure, fills the internal pores of the concrete, and effectively prevents water penetration. It is worth noting that the double bonds of the diacylhydrazone chain extender polymers obtained in Examples 2 and 3 are located on the polymer main chain. The π-electron cloud of the double bond restricts the rotation of the molecular chain segments to some extent, thereby increasing the rigidity of the molecular chain. Therefore, the compressive strength of the concrete in Examples 2 and 3 is slightly higher than that in Example 1.

[0097] Compared to Example 1, the polymerization of caffeic acid and isocyanate in Example 4 increased the content of carbon-carbon double bonds, resulting in superior temperature-suppressing and crack-resistant effects. The glyceric acid used in Example 5 lacked benzene rings and carbon-carbon double bonds, leading to a slight decrease in waterproofing performance compared to Example 1. Therefore, hydroxydiacids containing unsaturated bonds can be further preferred. In Example 6, the siloxane diol molecule contained additional tertiary amine groups, which could form more hydrogen bonds with concrete raw materials, thus resulting in different waterproofing performance. Furthermore, the tertiary amine groups made the waterproofing agent molecules slightly more hydrophilic than in Example 1, resulting in a higher 48-hour water absorption rate.

[0098] The results of Examples 1, 7-8, and Comparative Example 4 demonstrate the role of siloxane diols in waterproofing agents. The two silanyl groups in the siloxane diol readily hydrolyze into silanyl hydroxyl groups in alkaline concrete, which can combine with the silica in calcium silicate to form a network-like three-dimensional structure, improving the overall strength of the product. Furthermore, the hydrophobic siloxanes are neatly arranged on the capillary walls, hindering the penetration of water into the interior, making the concrete more waterproof overall. The proportion of siloxane diols in Examples 7, 1, and 8 increases sequentially, thus their waterproofing effect increases accordingly; in Comparative Example 4, no siloxane diol is added, and its waterproofing performance on concrete decreases slightly.

[0099] The test results of Examples 1-3 and Comparative Examples 1-3 demonstrate that the carbon-carbon double bonds, disulfide bonds, and acylhydrazone groups abundant in the waterproofing agent of the present invention work together to inhibit temperature and cracking, doubling the temperature inhibition rate and improving the impermeability by more than 25%. Furthermore, in conjunction with Examples 9-10, the proportion of the waterproofing agent in concrete should be appropriately adjusted according to the actual engineering needs. Too little will result in insufficient crack resistance and waterproofing performance of the concrete; too much will increase the flexibility of the concrete and sacrifice some compressive strength.

[0100] In summary, the temperature-suppressing and crack-resistant concrete waterproofing agent provided by this invention has significant and excellent temperature control, crack resistance and waterproofing effects. When applied to large-scale engineering concrete, it can meet the requirements of construction fields with high waterproofing requirements, such as underground engineering and hydraulic structures.

[0101] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A temperature-inhibiting and crack-resistant concrete waterproofing agent, characterized in that, Its raw materials include siloxane diol, dihydroxy acid, diisocyanate, catalyst, diacylhydrazone chain extender and water; The molar ratio of the diisocyanate, siloxane diol, dihydroxy acid, and diacylhydrazone chain extender is (1.98–2.05):(0.2–0.8):(0.2–0.8):(1.05–1.2); the solid content of the waterproofing agent is 20%–35%. The diacylhydrazone chain extender is synthesized by the following steps: 1) Dithiol hydrocarbons undergo an exchange reaction with disulfur dichloride to generate intermediate 1; 2) Intermediate 1 undergoes a substitution reaction with hydroxyenal to generate intermediate 2; 3) Intermediate 2 reacts with alkyl diacid hydrazide via a Schiff base reaction to yield a diacylhydrazone chain extender.

2. The concrete waterproofing agent as described in claim 1, characterized in that, The conditions for step 1) are as follows: Dithiol hydrocarbon and disulfur dichloride are reacted in a 1,4 dioxane medium under N-bromosuccinimide catalyst with sealed stirring for 2-4 hours; after the reaction is completed, the reaction mixture is concentrated under vacuum and then purified by silica gel chromatography to obtain intermediate 1; the molar ratio of the dithiol hydrocarbon, disulfur dichloride and N-bromosuccinimide is 1:(3.9-4.2):(1.0-1.2); the dithiol hydrocarbon includes C1-C5 aliphatic hydrocarbons containing two terminal thiol groups, thianes, benzene, biphenyl, naphthalene, diphenyl ether, and diphenyl sulfide.

3. The concrete waterproofing agent as described in claim 1, characterized in that, The conditions for step 2) are as follows: Under a nitrogen atmosphere, intermediate 1 and hydroxyenal are stirred in a dichloromethane, ethyl acetate, anhydrous ethanol, or acetone medium, with triethylamine as an acid-binding agent, in an ice bath at -5 to 5°C for 2 to 3 hours and in a water bath at 40 to 50°C for 6 to 12 hours. After the reaction is completed, the mixture is filtered, washed with saturated brine, acetone is removed by rotary evaporation under reduced pressure, and the mixture is concentrated and recrystallized to obtain intermediate 2. The molar ratio of hydroxyenal, intermediate 1, and triethylamine is 1:(1.1 to 1.5):(0.99 to 1.20). The hydroxyenal is an aldehyde compound containing at least one hydroxyl group and one carbon-carbon double bond.

4. The concrete waterproofing agent as described in claim 1, characterized in that, The conditions for step 3) are as follows: In anhydrous benzene, toluene, or ethanol, intermediate 2 and alkyl diacid hydrazide are heated under reflux in an oil bath at 50–60 °C for 6–9 h with acetic acid as a catalyst; after the reaction is completed, the mixture is filtered through a Buchner funnel, the solvent is removed by rotary evaporation, and the filtrate is concentrated to obtain the diacylhydrazone chain extender, which is then sealed and stored at low temperature under argon gas; the molar ratio of intermediate 2, alkyl diacid hydrazide, and acetic acid is 1:(2–2.2):(0.8–1.0); the alkyl diacid hydrazide is selected from one or more of C3–C12 aliphatic hydrocarbon diacid hydrazides, phthalic acid diacid hydrazides, isophthalic acid diacid hydrazides, and terephthalic acid diacid hydrazides.

5. The concrete waterproofing agent as described in claim 1, characterized in that, The siloxane diol is a siloxane substance containing two hydroxyl groups; the dihydroxy acid is a mono- or dicarboxylic acid containing two hydroxyl groups.

6. The concrete waterproofing agent as described in claim 1, characterized in that, The catalyst is added at a rate of 0.5% to 1.2% of the total mass of the system and is selected from one or more of dibutyltin dilaurate, hexamethylenediamine, N-alkyldiamine, N-alkylmorpholine, stannous octoate, zinc bismuth composite catalyst, bismuth isooctanoate, organic zinc, and zinc neocaprate.

7. The concrete waterproofing agent as described in claim 1, characterized in that, The diisocyanate is one or more of 4-toluene diisocyanate, trans-1,4-cyclohexyl diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, dicyclohexylmethane-4,4-diisocyanate, isophorone diisocyanate, 1,6-hexane diisocyanate, and lysine diisocyanate.

8. A method for preparing a temperature-inhibiting and crack-resistant concrete waterproofing agent as described in any one of claims 1 to 7, characterized in that, Includes the following steps: The dihydroxy acid and siloxane diol were subjected to vacuum dehydration and drying pretreatment at 120°C. Subsequently, under a nitrogen atmosphere, the dihydroxy acid and siloxane diol were added to a four-necked flask equipped with a mechanical stirrer, a reflux condenser, a thermometer, and a constant pressure dropping funnel, and stirred at room temperature. Gradually raise the temperature to 60–70°C, and dropwise add the mixture of diisocyanate and catalyst while stirring at 500–700 rpm. After the addition is complete, continue stirring at 60–70°C for 1–2 hours. Add an aprotic solvent to adjust the viscosity of the system, raise the temperature to 90–120°C, and stir at a constant temperature for 5–9 hours. Lower the system temperature to 40–60°C, add a diacylhydrazone chain extender, and stir at a constant temperature for 3–4 hours. Add a neutralizing agent until the pH of the system is 7.0–7.5 and stir for 30 minutes. Add deionized water and stir at high speed at 1000–1500 rpm for 30 minutes to emulsify and disperse. Remove the residual aprotic solvent by rotary evaporation to obtain a polyurethane emulsion-type waterproofing agent.

9. The preparation method according to claim 8, characterized in that, The aprotic solvent is one or more of butanone, dioxane, dimethylformamide, benzene, and toluene; the neutralizing agent is one of NH4OH, NaOH, monoethylamine, diethylamine, triethylamine, and triethanolamine.

10. The application of the temperature-suppressing and crack-resistant concrete waterproofing agent as described in any one of claims 1 to 7 in the preparation of concrete.

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