Cement mortar reinforcing agent and preparation method thereof

Abstract

The invention discloses a cement mortar reinforcing agent and a preparation method thereof, relates to the field of cement mortar reinforcing agents, and is characterized in that the limit ranges of the DEAIPA dosage (15-20 parts), the titanate coupling agent hydrolysis time (3-5 hours) and the main mixing reaction temperature (60-70 DEG C) are controlled. A titanate coupling agent is hydrolyzed at specific pH and temperature until the conversion rate of-SiOR groups is high, sodium polyacrylate adsorbs sodium bicarbonate to form CO2-loaded microspheres, then the CO2-loaded microspheres are mixed and reacted with raw materials such as calcium formate and DEAIPA at limited temperature, and finally the reinforcing agent is prepared. Ten groups of contrast experiments are designed for verification: 1-5 groups are conventional groups with parameters within a limited range, 6-9 groups are control groups with parameters exceeding the range, and 10 groups are traditional raw material blank groups. Experiments show that the 3-day / 28-day compressive strength and the total shrinkage rate of a conventional group are remarkably superior to those of an out-of-range group and a blank group, a nonlinear relation exists in the synergistic effect of parameters, and it is proved that the limited range has practical significance for improving the mechanical property and the crack resistance of the low-clinker cement.

Description

Technical Field

[0001] The present invention relates to the field of cement mortar reinforcing agents, in particular to a cement mortar reinforcing agent and a preparation method thereof. Background Art

[0002] At present, cement mortar enhancers mainly improve performance by accelerating cement hydration, filling pores or enhancing interface bonding. Traditional enhancers usually use amine substances such as triethanolamine to stimulate cement activity, but for low-clinker cement with clinker content ≤ 65%, the low-activity dicalcium silicate (C2S) is difficult to be effectively stimulated, resulting in early strength (3 days) of only 70-80% of the benchmark cement; interface enhancement mostly relies on silane coupling agents, but the hydrolysis of silane coupling agents is easily affected by pH value (especially in a high alkaline environment of cement), the hydrolysis products are easy to agglomerate, and the interface bonding effect is unstable. In addition, existing enhancers often use calcium nitrate to provide Ca 2+ Nucleus, but nitrate (NO3 - ) will accelerate the chloride ion (Cl - ) penetration, leading to the risk of steel corrosion. Regarding crack control, when superabsorbent resin is directly loaded with CO2 solution, the CO2 release rate is uncontrollable, which can easily lead to carbonization shrinkage cracks (shrinkage rate > 0.04%). At the process level, traditional mixing reactions must be carried out at 70-85°C, which consumes a lot of energy. Furthermore, to ensure strength, high clinker dosage (≥ 70%) is typically required, which conflicts with the cement industry's need for low-carbon development.

[0003] The above-mentioned existing technologies have the following drawbacks: First, due to the lack of active ingredients in low-clinker cement, traditional amines and coupling agents cannot synergistically achieve efficient strength improvement; second, the corrosion risk of calcium nitrate and the uncontrollable CO2 release rate coexist, making it difficult to simultaneously address multiple types of cracks; third, the poor hydrolytic stability of silane coupling agents leads to fluctuations in the performance of the reinforcing agents; fourth, the high clinker usage and high energy consumption process limit the achievement of low-carbon goals, and the reduction of clinker can easily lead to a decline in construction performance. Therefore, there is an urgent need for a cement mortar reinforcing agent that is compatible with low-clinker cement, has both crack resistance and low corrosion properties, and is stable in process and meets low-carbon requirements. Summary of the Invention

[0004] In view of the above-mentioned shortcomings of the prior art, the object of the present invention is to provide a cement mortar reinforcing agent and a preparation method thereof to solve one or more problems in the prior art.

[0005] To achieve the above object, the technical solution of the present invention is as follows:

[0006] A cement mortar enhancer comprising the following raw materials in parts by mass:

[0007] Active amines: 15-20 parts of diethanol monoisopropanolamine (DEAIPA).

[0008] Coupling agent: 5-8 parts of titanate coupling agent.

[0009] Inorganic salt: 20-25 parts of calcium formate.

[0010] Functional carrier: 10-15 parts of sodium polyacrylate.

[0011] Auxiliary agent: 3-5 parts of sucrose.

[0012] 40-50 parts of deionized water.

[0013] Furthermore, the titanate coupling agent is a TMC-TTS type titanate coupling agent.

[0014] Furthermore, the molecular weight of the sodium polyacrylate is 800,000-1.2 million.

[0015] Furthermore, the purity of the DEAIPA is ≥98%.

[0016] To achieve a complete technical effect, the second technical solution of the present invention is a method for preparing a cement mortar enhancer. This method, in conjunction with the first technical solution, includes the following steps:

[0017] (1) Hydrolysis pretreatment of titanate coupling agent: The titanate coupling agent is mixed with anhydrous ethanol and deionized water for hydrolysis.

[0018] (2) Sodium polyacrylate loaded with CO2 solution: Sodium polyacrylate is immersed in a sodium bicarbonate aqueous solution to form CO2 loaded microspheres.

[0019] (3) Main mixing reaction: The hydrolyzed titanate solution is mixed with calcium formate, DEAIPA, and sucrose, and then CO2-loaded microspheres are added and mixed continuously.

[0020] (4) Finished product packaging: sealed and packaged after cooling.

[0021] Furthermore, in step (1), the specific operation of the hydrolysis pretreatment of the titanate coupling agent is as follows: adding the titanate coupling agent dropwise to a mixture of anhydrous ethanol and deionized water (volume ratio 3:1), adjusting the pH to 4.0-5.0, stirring and hydrolyzing at 300 rpm at 35±2°C for 3-5 hours, and the conversion rate of -SiOR groups of the titanate coupling agent in the hydrolyzate is ≥90%.

[0022] Furthermore, the titanate coupling agent has a dropping rate of 2 mL / min.

[0023] Furthermore, in step (2), the specific operation of the sodium polyacrylate loaded CO2 solution is: adding sodium polyacrylate to a sodium bicarbonate aqueous solution with a concentration of 5-8%, stirring at 200 rpm for 30 minutes and then standing and soaking for 2 hours, and filtering to obtain CO2 loaded microspheres (particle size 10-50 μm) with a water content of 25-30%.

[0024] Furthermore, in step (3), the specific operation of the main mixing reaction is: mixing the hydrolyzed titanate solution with calcium formate, DEAIPA, and sucrose, stirring at 400 rpm for 30 minutes at 60-70°C (the viscosity of the mixed solution is stabilized at 80-120 mPa·s), and then adding CO2-loaded microspheres and stirring at 200 rpm for 15 minutes until the mixture is uniform and without stratification.

[0025] Furthermore, in step (4), the storage condition of the finished product packaging is a cool and dry environment (humidity ≤ 60%).

[0026] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0027] (1) Through the synergistic effect of the branched alkyl structure of diethanol monoisopropanolamine (DEAIPA) and the high bond energy interface of the titanate coupling agent, a high-efficiency strength improvement of low-clinker cement is achieved. DEAIPA, through its branched structure with less steric hindrance, is more easily combined with the low-activity dicalcium silicate (C2S) in the low-clinker and stimulates its hydration; the titanium hydroxyl (-TiOH) generated by the hydrolysis of the titanate coupling agent forms a higher bond energy -Ti-O-Si- bond (662kJ / mol) with the cement silicate (CSH gel), strengthening the interface bonding. The combination of the two increases the 3-day compressive strength of low-clinker (dosage ≤ 65%) cement by 15-20% compared to the existing technology (triethanolamine + silane coupling agent), and the 28-day strength by 9-16%, solving the strength defect of low-clinker cement caused by insufficient active ingredients.

[0028] (II) Through the coordinated design of the formate complexation of calcium formate and the CO2 release regulation of sodium polyacrylate, the crack resistance of cement mortar is optimized. - ) and Ca 2+ The formation of a stable complex slows the rate of heat release from cement hydration (reducing it by 20-25%), thus reducing thermal stress cracking. Sodium polyacrylate, through its hydrophilic groups (-COONa), loads sodium bicarbonate solution, regulating the CO2 release rate (shrinkage ≤ 0.03%) and reducing carbonization shrinkage cracking. The combination of these two reduces the overall shrinkage of cement mortar by 40-45% compared to existing technologies (calcium nitrate + superabsorbent resin), effectively controlling the occurrence of various types of cracks.

[0029] (III) By replacing calcium nitrate with calcium formate and controlling the stability of the titanate coupling agent hydrolysis process, the dual guarantee of low corrosion and enhancer performance is achieved. Calcium formate only provides Ca 2+ Crystal nucleus without oxidizing nitrate (NO3 - ), eliminating the risk of electrochemical corrosion of steel bars (corrosion rate reduced by over 90%); titanate coupling agents exhibit more stable hydrolysis at pH 4.0-5.0 and 35±2°C (-SiOR conversion ≥ 90%), avoiding the hydrolysis failure of silane coupling agents caused by pH fluctuations. This combination of the two eliminates the corrosion risks associated with existing reinforcing agents while also improving product process reliability.

[0030] (IV) Through the multi-dimensional synergy of DEAIPA's low clinker adaptability, the reduction of the main mixing reaction temperature (60-70°C) and the adjustment of the workability of sucrose, a balance between low-carbon demand and material performance is achieved. DEAIPA's efficient stimulation of low clinker allows a 10-15% reduction in clinker usage (in line with the cement industry's carbon reduction goals); the main mixing reaction temperature is reduced by 10-25°C compared to the existing technology (70-85°C), reducing energy consumption; sucrose improves the workability of mortar by adjusting the hydration rate, avoiding the decline in construction performance due to the reduction of clinker. The combination of the three ensures the construction applicability and mechanical properties of cement mortar while reducing carbon emissions. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the preparation process of the cement mortar strengthener of the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and exemplary explanations. It should be noted that the structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification for people familiar with this technology to understand and read, and are not intended to limit the conditions for the implementation of the present invention. Therefore, they have no technical significance. Any modification of the structure, change in the proportion relationship or adjustment of the size should still fall within the scope of the technical content disclosed in the present invention without affecting the efficacy and purpose of the present invention.

[0033] Application Overview

[0034] In the field of building materials, for the strength improvement and performance optimization of low-clinker cement (clinker content ≤ 65%), the conventional treatment methods in the industry mainly rely on traditional amines (such as triethanolamine) to stimulate cement activity, silane coupling agents to enhance interface bonding, and calcium nitrate to provide Ca 2+The crystal nucleus accelerates hydration, and the cracks are controlled by loading CO2 solution with super absorbent resin, and the strength is guaranteed by relying on high clinker dosage (dosage ≥ 70%). However, these conventional solutions have significant shortcomings: triethanolamine has limited efficiency in stimulating the low-activity dicalcium silicate (C2S) in low-clinker, resulting in early strength of only 70-80% of the benchmark cement; the hydrolysis of silane coupling agents is easily affected by the high alkaline environment of cement, the hydrolysis products are easy to agglomerate, and the interface bonding effect is unstable; the nitrate ions (NO3 - ) accelerates chloride ion penetration, leading to the risk of steel corrosion; when superabsorbent resin is directly loaded with CO2 solution, the release rate is uncontrollable, which can easily lead to carbonization shrinkage cracks (shrinkage rate > 0.04%); in addition, high clinker usage conflicts with the demand for low-carbon development, while reducing clinker usage will lead to reduced workability due to insufficient activity. These problems have long restricted the large-scale application and green development of low-clinker cement.

[0035] Comprehensive description

[0036] This invention relates to a cement mortar strengthener and its preparation method. Through a specific raw material ratio and process design, it addresses the technical challenges of increasing the strength of low-clinker cement, optimizing crack resistance, ensuring low corrosion resistance, and achieving low-carbon adaptability. The following details the specific raw material selection and preparation process.

[0037] 1. Raw material composition and selection

[0038] The cement mortar strengthener of the present invention is composed of the following raw materials in parts by mass:

[0039] Active amines: Use diethanol monoisopropanolamine (DEAIPA), an industrial-grade product with a purity of ≥98%, in a dosage of 15-20 parts. This amine has a branched alkyl structure and, compared to traditional triethanolamine, is more likely to bind to the less active dicalcium silicate (C2S) and stimulate its hydration activity.

[0040] Coupling agent: Use TMC-TTS titanate coupling agent in a dosage of 5-8 parts. Titanate coupling agent generates titanium hydroxyl (-TiOH) through hydrolysis, which can form high-energy -Ti-O-Si- bonds (bond energy of approximately 662kJ / mol) with silicate (CSH gel) in cement, strengthening the interface bonding.

[0041] Inorganic salt: calcium formate is used in an amount of 20-25 parts. Calcium formate provides Ca 2+ At the same time as the crystal nucleus, its formate (-HCOO - ) can be combined with Ca 2+ Form a stable complex and slow down the heat release rate of cement hydration.

[0042] Functional carrier: Sodium polyacrylate with a molecular weight of 800,000-1.2 million is used in an amount of 10-15 parts. Its hydrophilic group (-COONa) can load sodium bicarbonate solution to form CO2-loaded microspheres, thereby regulating the CO2 release rate.

[0043] Adjuvant: Use sucrose in a dosage of 3-5 parts. Sucrose can improve the workability of mortar by regulating the hydration rate of cement, thus avoiding the degradation of construction performance caused by the reduction of clinker.

[0044] Deionized water: 40-50 parts is used to dissolve and disperse the components.

[0045] 2. Preparation method and process parameter control

[0046] The preparation process of the cement mortar strengthener of the present invention comprises the following key steps:

[0047] 1. Hydrolysis pretreatment of titanate coupling agent

[0048] Take anhydrous ethanol and deionized water in a volume ratio of 3:1 to prepare a hydrolysis medium. Slowly add titanate coupling agent to the medium (the drop rate is controlled at 2mL / min), and adjust the pH to 4.0-5.0 with dilute hydrochloric acid (a weakly acidic environment can inhibit excessive hydrolysis of titanate). Place the mixed solution in a constant temperature water bath, control the temperature to 35±2°C, and stir at 300rpm for hydrolysis for 3-5 hours. After the hydrolysis is completed, the conversion rate of the -SiOR group of the titanate coupling agent in the hydrolyzate is detected (needed to be ≥90%) to ensure that the active group of the coupling agent is fully exposed.

[0049] 2. Sodium polyacrylate loaded CO2 solution

[0050] Sodium polyacrylate with a molecular weight of 800,000-1.2 million is added to a 5-8% sodium bicarbonate aqueous solution and stirred at 200 rpm for 30 minutes to allow the sodium polyacrylate to fully swell and absorb the sodium bicarbonate. The mixture is then allowed to soak for 2 hours to allow the sodium bicarbonate to form a stable CO2-loaded structure within the sodium polyacrylate. Excess solution is filtered to remove CO2-loaded microspheres (10-50 μm in size) with a moisture content of 25-30%. These microspheres slowly release CO2, regulating the carbonation shrinkage rate of cement mortar.

[0051] 3. Main Mix Reaction

[0052] The hydrolyzed titanate solution, calcium formate, DEAIPA, and sucrose were sequentially added to the reactor, and the heating and stirring devices were turned on. The reaction temperature was controlled at 60-70°C (10-25°C lower than the traditional process, reducing energy consumption) and stirred at 400 rpm for 30 minutes, until the viscosity of the mixture stabilized at 80-120 mPa·s (stable viscosity indicates that the components are fully dispersed and a preliminary complexation reaction has occurred). CO2-loaded microspheres were then added, and the stirring speed was reduced to 200 rpm. Stirring was continued for 15 minutes until the mixture was homogeneous and free of stratification.

[0053] 4. Finished product packaging

[0054] After the mixing reaction is complete, turn off the heating device and allow the mixture to cool naturally to room temperature (about 25°C). Transfer the product to a sealed container and store it in a cool, dry environment (humidity ≤ 60%) to avoid moisture absorption or reaction with acidic gases in the air, which may affect the performance of the enhancer.

[0055] 3. Process design principles and key control points

[0056] The present invention achieves performance optimization through the coordinated design of raw material ratios and process parameters:

[0057] The branched structure of DEAIPA combines with the high bond energy interface of the titanate coupling agent to specifically solve the problem of insufficient C2S activity in low-clinker cement;

[0058] The formate complexation of calcium formate and the CO2 release regulation of sodium polyacrylate jointly inhibit temperature stress cracks and carbonization shrinkage cracks;

[0059] The weakly acidic hydrolysis conditions (pH 4.0-5.0) and hydrolysis conversion rate control (≥90%) of the titanate coupling agent ensure the stability of the coupling agent activity;

[0060] The reduction of the main mixing reaction temperature (60-70°C) and the adjustment of the workability of sucrose balance the low carbon demand and construction performance.

[0061] Those skilled in the art can adjust the specific values ​​(such as 15-20 parts of DEAIPA and 3-5 hours of hydrolysis time) within the above-mentioned raw material ratios and process parameters according to actual application requirements, and the technical effects described in the present invention can be achieved.

[0062] Experimental verification and performance testing

[0063] In order to verify the actual influence of the key parameters of the cement mortar enhancer described in the present invention on the performance, a comparative experiment was designed. The influence of core parameters (DEAIPA dosage, titanate coupling agent hydrolysis time, and main mixing reaction temperature) on the mechanical properties and crack resistance of cement mortar was analyzed by the controlled variable method, and the effectiveness of the technical solution was verified in combination with the national standard test method.

[0064] Experimental design description

[0065] Experimental objectives: To verify the effects of the DEAIPA dosage, titanate coupling agent hydrolysis time, and main mixing reaction temperature on the 3-day compressive strength, 28-day compressive strength, and total shrinkage of cement mortar, and to demonstrate the practical significance of the parameter limit range.

[0066] Variable selection: DEAIPA dosage (denoted as A), titanate coupling agent hydrolysis time (denoted as B), and main mixing reaction temperature (denoted as C) were selected as experimental variables. A was limited to 15-20 parts by mass, B was limited to 3-5 hours, and C was limited to 60-70°C.

[0067] Experimental group setting: A total of 10 groups of experiments were designed, of which groups 1-5 were conventional groups (variables were within the specified range), groups 6-9 were out-of-range control groups (variables exceeded the specified range), and group 10 was a blank control group (using existing technology: traditional enhancer of triethanolamine + silane coupling agent + calcium nitrate).

[0068] Test standards:

[0069] Compressive strength: According to GB / T 17671-1999 "Test method for strength of cement mortar (ISO method)", 40mm×40mm×160mm mortar specimens were prepared and the compressive strength was tested at 3 days and 28 days.

[0070] Total shrinkage: Based on GB / T 50082-2009 “Standard for test methods for long-term properties and durability of ordinary concrete”, a contact extensometer was used to measure the free shrinkage of the specimens at 14 days of age.

[0071] Performance parameter recording: Each set of experiments records three core indicators: 3-day compressive strength (MPa), 28-day compressive strength (MPa), and total shrinkage (%).

[0072] Comprehensive scoring rules: Use weighted scoring method, 3-day compressive strength (weight 30%), 28-day compressive strength (weight 40%), total shrinkage (weight 30%), where shrinkage is a reverse indicator (the smaller the value, the higher the score). The scoring formula is:

[0073] Comprehensive score = 0.3 × (3-day strength / maximum value) × 100 + 0.4 × (28-day strength / maximum value) × 100 + 0.3 × (1-shrinkage rate / maximum value) × 100

[0074] Experimental condition control

[0075] All experimental groups have the same conditions except for the following variables:

[0076] Cement mortar ratio: cement (clinker content 60%): sand: water: reinforcing agent = 1:3:0.5:0.02 (mass ratio);

[0077] Environmental parameters: curing temperature 20±2℃, relative humidity 95±5%;

[0078] Other raw materials: 6 parts of titanate coupling agent (TMC-TTS type), 22 parts of calcium formate, 12 parts of sodium polyacrylate, 4 parts of sucrose, and 45 parts of deionized water.

[0079] Experimental results and analysis

[0080] Experimental group performance test results table

[0081]

[0082]

[0083] Experimental conclusion analysis:

[0084] The 3-day compressive strength (32.4-35.8 MPa) of the conventional group (groups 1-5) increased by 28.6%-42.0% compared with the blank group (25.2 MPa), and the 28-day compressive strength (50.2-55.6 MPa) increased by 23.9%-37.3%, and the total shrinkage rate (0.027%-0.034%) decreased by 32.0%-46.0%. The comprehensive score (82.1-85.9) was significantly higher than that of other groups, indicating that the parameter combination within the limited range can effectively improve the mechanical properties and crack resistance of low-clinker cement.

[0085] The 3-day strength (27.9-29.3MPa), 28-day strength (44.3-46.8MPa) and shrinkage rate (0.039%-0.045%) of the out-of-range control group (groups 6-9) were all between the conventional group and the blank group, and at least one indicator (such as shrinkage rate) had a significant difference compared with the conventional group (for example, the shrinkage rate of group 6 was 0.042%, which was 23.5% higher than the highest value of 0.034% in the conventional group), indicating that parameters exceeding the limit range will lead to performance degradation.

[0086] The third group with the highest comprehensive score (85.9 points) did not appear in the first or last group, and fluctuated with the scores of other conventional groups (82.1-84.6 points), indicating that there is a nonlinear relationship between the synergistic effects of DEAIPA dosage, hydrolysis time and reaction temperature, and it is necessary to balance the influence of multiple parameters within a limited range, verifying the necessity of parameter range setting.

[0087] The above experiments show that the limited range of DEAIPA dosage, titanate coupling agent hydrolysis time and main mixing reaction temperature in the present invention can significantly improve the mechanical properties and crack resistance of low-clinker cement mortar, and is superior to the existing technology and out-of-range parameter combinations, and has clear practical significance.

[0088] Weighted scoring analysis of experimental data and interpretation of molecular mechanisms

[0089] 1. Correlation between comprehensive score trends and experimental data

[0090] The comprehensive scores of the experimental data showed that the conventional groups (groups 1-5, scores of 82.1-85.9) were significantly higher than those of the out-of-range groups (groups 6-9, scores of 69.8-73.5) and the blank group (group 10, 62.4 points). Group 3 (85.9 points) achieved the highest score, reflecting that the combination of DEAIPA dosage (19 parts per ml), hydrolysis time (5 hours), and reaction temperature (70°C) achieved the optimal synergistic effect within the specified range. The out-of-range groups, however, experienced significant declines in some performance indicators (such as 3-day strength and shrinkage) due to parameter deviations from the specified values. The blank group, due to its use of conventional raw materials, had the lowest performance indicators across all groups.

[0091] 2. The underlying mechanism of molecular-level performance differences

[0092] (1) Effect of DEAIPA dosage on strength

[0093] In the molecular structure of DEAIPA (diethanol monoisopropanolamine), the steric hindrance of the branched alkyl group (-CH(CH3)2) has a higher compatibility with the calcium oxygen octahedron (CaO6) structure on the surface of low-activity C2S (dicalcium silicate). When the dosage of DEAIPA is 15-20 parts, its amino group (-NH-) can react with the CaO6 on the surface of C2S. 2+ It forms a stable coordination bond (bond energy of about 210 kJ / mol), reduces the hydrolysis activation energy of C2S (from about 65 kJ / mol to 50 kJ / mol) through the electron induction effect, and accelerates the hydration of C2S to form CSH gel (hydrated calcium silicate).

[0094] If the dosage of DEAIPA is less than 15 parts (such as in groups 6 and 8), the coordination sites are insufficient, the degree of C2S hydration is only 60%-70% of the baseline, and the 3-day strength (27.9-28.6 MPa) is 12%-21% lower than that of the conventional group (32.4-35.8 MPa);

[0095] If the dosage is higher than 20 parts (such as Groups 7 and 9), the excess amino groups will react with Ca 2+Competitive adsorption was formed to inhibit the continuous growth of CSH gel, and the strength at 28 days (45.7-46.8 MPa) was reduced by 7%-18% compared with the conventional group (50.2-55.6 MPa).

[0096] (2) Effect of titanate hydrolysis time on interface bonding

[0097] The titanyl (-TiOH) generated by the hydrolysis of the titanate coupling agent (TMC-TTS) undergoes dehydration condensation with the silanol (-SiOH) groups on the surface of the CSH gel in the cement, forming a -Ti-O-Si- covalent bond (bond energy approximately 662 kJ / mol), strengthening the interface between the aggregate and the paste. A hydrolysis time of 3-5 hours ensures a -SiOR group conversion rate of ≥90% (2-3 -TiOH groups exposed per coupling agent molecule).

[0098] When the hydrolysis time was shorter than 3 hours (e.g., groups 6 and 8), the -SiOR group conversion rate was only 60%-70%, the number of -TiOH groups was insufficient, and the interfacial bonding strength decreased (manifested by a total shrinkage of 0.042%-0.045%, 23%-67% higher than the conventional group's 0.027%-0.034%).

[0099] When the hydrolysis time is longer than 5 hours (such as Groups 7 and 9), titanium hydroxyl groups are prone to self-polymerization (-TiOH+-TiOH→-Ti-O-Ti-+H2O), forming inert titanium oxide polymers, which lose their reactivity with silicon hydroxyl groups, and the strength improvement after 28 days is reduced (12%-15% lower than the conventional group).

[0100] (III) Regulation of the main mixing reaction temperature on complexation and release

[0101] The main mixed reaction temperature is 60-70℃, which is the time for calcium formate and Ca 2+ The key condition for the formation of complex and the loading of CO2 by sodium polyacrylate. At this temperature, formate (-HCOO - ) and Ca 2+ The five-membered ring complex ([Ca(HCOO)2(H2O)2]) is formed by electrostatic interaction to stabilize Ca 2+ concentration and slow down the hydration exothermic rate (the exothermic peak value dropped from about 50 J / g to 35 J / g); at the same time, the carboxylate group (-COO - ) adsorbs sodium bicarbonate (NaHCO3) through hydrogen bonds to form CO2-loaded microspheres (particle size 10-50μm) and control the CO2 release rate (about 0.05-0.1mmol / h).

[0102] When the temperature is lower than 60℃ (such as Groups 6 and 8), the complexation rate of calcium formate decreases. 2+The increase in free ion concentration (from about 0.02 mol / L to 0.03 mol / L) accelerated early hydration (the strength at 3 days was only slightly higher than that of the blank group), but the concentrated exotherm led to an increase in temperature stress cracks (shrinkage rate 0.042%-0.045%).

[0103] When the temperature is higher than 70℃ (such as Groups 7 and 9), the calcium formate complex decomposes (the decomposition temperature is about 75℃), the formate ion desorbs, and Ca 2+ The free ion concentration increased sharply (0.04 mol / L), the hydration rate was too fast, the CSH gel structure was loose (the strength after 28 days was only 45.7-46.8 MPa), and at the same time, the CO2-loaded microspheres ruptured due to thermal expansion (particle size > 50 μm), the CO2 release rate surged (0.2-0.3 mmol / h), and the carbonization shrinkage intensified (shrinkage rate 0.039%-0.041%).

[0104] (IV) Molecular mechanism defects in the blank group

[0105] The blank group used the traditional triethanolamine + silane coupling agent + calcium nitrate system:

[0106] Triethanolamine (TEA) is a straight-chain amine with poor steric matching with the C2S surface. It can only activate the hydration of C3S (tricalcium silicate). The activation efficiency of C2S is insufficient (the degree of C2S hydration is only 50%), resulting in a significantly lower strength of 25.2 MPa after 3 days than the conventional group.

[0107] The silanol (-SiOH) generated by the hydrolysis of silane coupling agent (such as KH-550) is easily deprotonated (-SiOH→-SiO - +H + ), and Ca 2+ The formation of calcium silicate precipitation (CaSiO3) and loss of interface bonding function;

[0108] NO3 provided by calcium nitrate (Ca(NO3)2) - With Cl - Ion exchange occurs (NO3 - +Cl - →NO3 - +Cl - ), accelerating Cl - Migrate to the steel bar surface (Cl- permeability coefficient from 0.5×10 -12 m 2 / s increased to 1.2×10 -12 m 2 / s), causing the risk of corrosion, while NO3 - It does not participate in the hydration reaction and the shrinkage rate cannot be controlled (shrinkage rate 0.050%).

[0109] 3. Molecular explanation of nonlinear relationships

[0110] Group 3 (DEAIPA = 19 parts, hydrolysis time = 5 hours, reaction temperature = 70°C), which had the highest overall score, did not appear in the first or last group. This is due to the synergy and competition between the three variables at the molecular level:

[0111] Although increasing the dosage of DEAIPA can enhance C2S activation, excessive dosage will inhibit the growth of CSH gel;

[0112] Although prolonging the hydrolysis time can increase the number of -TiOH groups, too long a time will lead to self-aggregation of titanium hydroxyl groups;

[0113] Although increasing the reaction temperature can promote complexation and loading, too high a temperature will destroy the complex structure.

[0114] The optimal balance point of the three needs to be achieved within a limited range (A = 15-20 parts, B = 3-5 hours, C = 60-70°C), reflecting the dynamic balance of multi-molecular reaction pathways rather than the linear correlation of a single variable.

[0115] In summary, the performance trend of the experimental data is essentially the result of the synergistic effect of the raw material structure matching at the molecular level, the number of reactive groups, the stability of the complex and the CO2 release rate, which verifies the key significance of the parameter limit range of the present invention for improving the performance of low-clinker cement mortar.

[0116] Example

[0117] Example 1

[0118] Take anhydrous ethanol and deionized water in a volume ratio of 3:1 to mix and prepare 500mL of hydrolysis medium. Slowly add 6 parts of TMC-TTS type titanate coupling agent to the medium (drop rate 2mL / min), and adjust the pH to 4.2 with dilute hydrochloric acid. Place the mixture in a 35°C constant temperature water bath and stir at 300rpm for hydrolysis for 3 hours (after hydrolysis, the -SiOR group conversion rate is 91%). Add 12 parts of sodium polyacrylate with a molecular weight of 1 million to a 6% sodium bicarbonate aqueous solution and stir at 200rpm for 30 minutes until it is fully swollen and adsorbs sodium bicarbonate. Then let it stand and soak for 2 hours to form a stable CO2-loaded structure. After filtering and removing the excess solution, CO2-loaded microspheres with a water content of 28% and a particle size of 30μm are obtained. To the reactor, add the hydrolyzed titanate solution, 22 parts of calcium formate, 15 parts of DEAIPA (diethanol monoisopropanolamine), and 4 parts of sucrose in sequence. Turn on the heating and stirring device, control the reaction temperature to 60°C, and stir at 400 rpm for 30 minutes until the viscosity of the mixed solution stabilizes at 85mPa·s. Then add CO2-loaded microspheres, reduce the stirring speed to 200 rpm, and continue stirring for 15 minutes until the system is uniform and there is no stratification. Turn off the heating device, cool the product naturally to 25°C, transfer it to a sealed container, and store it in a cool, dry environment with a humidity of 55%.

[0119] Example 2

[0120] Take anhydrous ethanol and deionized water in a volume ratio of 3:1 to mix and prepare 500mL of hydrolysis medium. Slowly add 6 parts of TMC-TTS type titanate coupling agent to the medium (drop rate 2mL / min), and adjust the pH to 4.3 with dilute hydrochloric acid. Place the mixture in a 35°C constant temperature water bath and stir at 300rpm for 4 hours (after hydrolysis, the -SiOR group conversion rate is 93%). Add 12 parts of sodium polyacrylate with a molecular weight of 1 million to a 6% sodium bicarbonate aqueous solution and stir at 200rpm for 30 minutes until it is fully swollen and adsorbs sodium bicarbonate. Then let it stand and soak for 2 hours to form a stable CO2-loaded structure. After filtering and removing the excess solution, CO2-loaded microspheres with a water content of 28% and a particle size of 30μm are obtained. The hydrolyzed titanate solution, 22 parts of calcium formate, 17 parts of DEAIPA (diethanol monoisopropanolamine), and 4 parts of sucrose were added to the reactor in sequence. The heating and stirring device was turned on, the reaction temperature was controlled at 65°C, and the mixture was stirred at 400 rpm for 30 minutes until the viscosity of the mixed solution stabilized at 88 mPa·s. Subsequently, CO2-loaded microspheres were added, the stirring speed was reduced to 200 rpm, and stirring was continued for 15 minutes until the system was uniform and without stratification. The heating device was turned off, the product was naturally cooled to 25°C, transferred to a sealed container, and stored in a cool, dry environment with a humidity of 55%.

[0121] Example 3

[0122] Take anhydrous ethanol and deionized water in a volume ratio of 3:1 and mix them to form 500mL of hydrolysis medium. Slowly add 6 parts of TMC-TTS type titanate coupling agent to the medium (drop rate 2mL / min), and adjust the pH to 4.1 with dilute hydrochloric acid. Place the mixture in a 35°C constant temperature water bath and stir at 300rpm for hydrolysis for 5 hours (after hydrolysis, the -SiOR group conversion rate is 95%). Add 12 parts of sodium polyacrylate with a molecular weight of 1 million to a 6% sodium bicarbonate aqueous solution and stir at 200rpm for 30 minutes until it is fully swollen and absorbs sodium bicarbonate. Then let it stand and soak for 2 hours to form a stable CO2-loaded structure. After filtering and removing the excess solution, CO2-loaded microspheres with a water content of 28% and a particle size of 30μm are obtained. To the reactor, add the hydrolyzed titanate solution, 22 parts of calcium formate, 19 parts of DEAIPA (diethanol monoisopropanolamine), and 4 parts of sucrose in sequence. Turn on the heating and stirring device, control the reaction temperature to 70°C, and stir at 400 rpm for 30 minutes until the viscosity of the mixed solution stabilizes at 92 mPa·s. Then add CO2-loaded microspheres, reduce the stirring speed to 200 rpm, and continue stirring for 15 minutes until the system is uniform and there is no stratification. Turn off the heating device, cool the product naturally to 25°C, transfer it to a sealed container, and store it in a cool, dry environment with a humidity of 55%.

[0123] Example 4

[0124] Take anhydrous ethanol and deionized water in a volume ratio of 3:1 to mix and prepare 500mL of hydrolysis medium. Slowly add 6 parts of TMC-TTS type titanate coupling agent to the medium (drop rate 2mL / min), and adjust the pH to 4.4 with dilute hydrochloric acid. Place the mixture in a 35°C constant temperature water bath and stir at 300rpm for 4.5 hours (after hydrolysis, the -SiOR group conversion rate is 94%). Add 12 parts of sodium polyacrylate with a molecular weight of 1 million to a 6% sodium bicarbonate aqueous solution and stir at 200rpm for 30 minutes until it is fully swollen and adsorbs sodium bicarbonate. Then let it stand and soak for 2 hours to form a stable CO2-loaded structure. After filtering and removing the excess solution, CO2-loaded microspheres with a water content of 28% and a particle size of 30μm are obtained. To the reactor, add the hydrolyzed titanate solution, 22 parts of calcium formate, 20 parts of DEAIPA (diethanol monoisopropanolamine), and 4 parts of sucrose in sequence. Turn on the heating and stirring device, control the reaction temperature to 63°C, and stir at 400 rpm for 30 minutes until the viscosity of the mixed solution stabilizes at 89 mPa·s. Then add CO2-loaded microspheres, reduce the stirring speed to 200 rpm, and continue stirring for 15 minutes until the system is uniform and there is no stratification. Turn off the heating device, cool the product naturally to 25°C, transfer it to a sealed container, and store it in a cool, dry environment with a humidity of 55%.

[0125] Example 5

[0126] Take anhydrous ethanol and deionized water in a volume ratio of 3:1 and mix them to form 500mL of hydrolysis medium. Slowly add 6 parts of TMC-TTS type titanate coupling agent to the medium (drop rate 2mL / min), and adjust the pH to 4.2 with dilute hydrochloric acid. Place the mixture in a 35°C constant temperature water bath and stir at 300rpm for 3.5 hours (after hydrolysis, the -SiOR group conversion rate is 92%). Add 12 parts of sodium polyacrylate with a molecular weight of 1 million to a 6% sodium bicarbonate aqueous solution and stir at 200rpm for 30 minutes until it is fully swollen and absorbs sodium bicarbonate. Then let it stand and soak for 2 hours to form a stable CO2-loaded structure. After filtering and removing the excess solution, CO2-loaded microspheres with a water content of 28% and a particle size of 30μm are obtained. To the reactor, add the hydrolyzed titanate solution, 22 parts of calcium formate, 18 parts of DEAIPA (diethanol monoisopropanolamine), and 4 parts of sucrose in sequence. Turn on the heating and stirring device, control the reaction temperature to 67°C, and stir at 400 rpm for 30 minutes until the viscosity of the mixed solution stabilizes at 90 mPa·s. Then add CO2-loaded microspheres, reduce the stirring speed to 200 rpm, and continue stirring for 15 minutes until the system is uniform and there is no stratification. Turn off the heating device, cool the product naturally to 25°C, transfer it to a sealed container, and store it in a cool, dry environment with a humidity of 55%.

[0127] Example 6

[0128] Take anhydrous ethanol and deionized water in a volume ratio of 3:1 and mix them to form 500mL of hydrolysis medium. Slowly add 6 parts of TMC-TTS titanate coupling agent to the medium (drop rate 2mL / min). At the same time, adjust the pH to 4.5 with dilute hydrochloric acid. Place the mixture in a 35°C constant temperature water bath and stir at 300rpm for 2.5 hours (after hydrolysis, the -SiOR group conversion rate is 88%). Add 12 parts of sodium polyacrylate with a molecular weight of 1 million to a 6% sodium bicarbonate aqueous solution and stir at 200rpm for 30 minutes until it is fully swollen and absorbs sodium bicarbonate. Then let it stand and soak for 2 hours to form a stable CO2-loaded structure. After filtering and removing the excess solution, CO2-loaded microspheres with a water content of 28% and a particle size of 30μm are obtained. To the reactor, add the hydrolyzed titanate solution, 22 parts of calcium formate, 14 parts of DEAIPA (diethanol monoisopropanolamine), and 4 parts of sucrose in sequence. Turn on the heating and stirring device, control the reaction temperature to 55°C, and stir at 400 rpm for 30 minutes until the viscosity of the mixed solution stabilizes at 78 mPa·s. Then add CO2-loaded microspheres, reduce the stirring speed to 200 rpm, and continue stirring for 15 minutes until the system is uniform and there is no stratification. Turn off the heating device, cool the product naturally to 25°C, transfer it to a sealed container, and store it in a cool, dry environment with a humidity of 55%.

[0129] Example 7

[0130] Take anhydrous ethanol and deionized water in a volume ratio of 3:1 to mix and prepare 500mL of hydrolysis medium. Slowly add 6 parts of TMC-TTS type titanate coupling agent to the medium (drop rate 2mL / min), and adjust the pH to 4.0 with dilute hydrochloric acid. Place the mixture in a 35°C constant temperature water bath and stir at 300rpm for hydrolysis for 5.5 hours (after hydrolysis, the -SiOR group conversion rate is 85%). Add 12 parts of sodium polyacrylate with a molecular weight of 1 million to a 6% sodium bicarbonate aqueous solution and stir at 200rpm for 30 minutes until it is fully swollen and adsorbs sodium bicarbonate. Then let it stand and soak for 2 hours to form a stable CO2-loaded structure. After filtering and removing the excess solution, CO2-loaded microspheres with a water content of 28% and a particle size of 30μm are obtained. To the reactor, add the hydrolyzed titanate solution, 22 parts of calcium formate, 21 parts of DEAIPA (diethanol monoisopropanolamine), and 4 parts of sucrose in sequence. Turn on the heating and stirring device, control the reaction temperature to 75°C, and stir at 400 rpm for 30 minutes until the viscosity of the mixed solution stabilizes at 105 mPa·s. Then add CO2-loaded microspheres, reduce the stirring speed to 200 rpm, and continue stirring for 15 minutes until the system is uniform and there is no stratification. Turn off the heating device, cool the product naturally to 25°C, transfer it to a sealed container, and store it in a cool, dry environment with a humidity of 55%.

[0131] Example 8

[0132] Take anhydrous ethanol and deionized water in a volume ratio of 3:1 to mix and prepare 500mL of hydrolysis medium. Slowly add 6 parts of TMC-TTS type titanate coupling agent to the medium (drop rate 2mL / min), and adjust the pH to 4.6 with dilute hydrochloric acid. Place the mixture in a 35°C constant temperature water bath and stir at 300rpm for 2 hours (after hydrolysis, the -SiOR group conversion rate is 82%). Add 12 parts of sodium polyacrylate with a molecular weight of 1 million to a 6% sodium bicarbonate aqueous solution and stir at 200rpm for 30 minutes until it is fully swollen and adsorbs sodium bicarbonate. Then let it stand and soak for 2 hours to form a stable CO2-loaded structure. After filtering and removing the excess solution, CO2-loaded microspheres with a water content of 28% and a particle size of 30μm are obtained. To the reactor, add the hydrolyzed titanate solution, 22 parts of calcium formate, 13 parts of DEAIPA (diethanol monoisopropanolamine), and 4 parts of sucrose in sequence. Turn on the heating and stirring device, control the reaction temperature to 50°C, and stir at 400 rpm for 30 minutes until the viscosity of the mixed solution stabilizes at 75mPa·s. Then add CO2-loaded microspheres, reduce the stirring speed to 200 rpm, and continue stirring for 15 minutes until the system is uniform and there is no stratification. Turn off the heating device, cool the product naturally to 25°C, transfer it to a sealed container, and store it in a cool, dry environment with a humidity of 55%.

[0133] Embodiment 9

[0134] Take anhydrous ethanol and deionized water in a volume ratio of 3:1 to mix and prepare 500mL of hydrolysis medium. Slowly add 6 parts of TMC-TTS type titanate coupling agent to the medium (drop rate 2mL / min), and adjust the pH to 4.1 with dilute hydrochloric acid. Place the mixture in a 35°C constant temperature water bath and stir at 300rpm for 6 hours (after hydrolysis, the -SiOR group conversion rate is 80%). Add 12 parts of sodium polyacrylate with a molecular weight of 1 million to a 6% sodium bicarbonate aqueous solution and stir at 200rpm for 30 minutes until it is fully swollen and adsorbs sodium bicarbonate. Then let it stand and soak for 2 hours to form a stable CO2-loaded structure. After filtering and removing the excess solution, CO2-loaded microspheres with a water content of 28% and a particle size of 30μm are obtained. To the reactor, add the hydrolyzed titanate solution, 22 parts of calcium formate, 22 parts of DEAIPA (diethanol monoisopropanolamine), and 4 parts of sucrose in sequence. Turn on the heating and stirring device, control the reaction temperature to 80°C, and stir at 400 rpm for 30 minutes until the viscosity of the mixed solution stabilizes at 110 mPa·s. Then add CO2-loaded microspheres, reduce the stirring speed to 200 rpm, and continue stirring for 15 minutes until the system is uniform and there is no stratification. Turn off the heating device, cool the product naturally to 25°C, transfer it to a sealed container, and store it in a cool, dry environment with a humidity of 55%.

[0135] Example 10 (blank control group)

[0136] Take anhydrous ethanol and deionized water in a volume ratio of 3:1 to prepare 500mL of hydrolysis medium, slowly add 6 parts of silane coupling agent (KH-550 type) to the medium (drop rate 2mL / min), and adjust the pH to 4.5 with dilute hydrochloric acid. Place the mixture in a 35°C constant temperature water bath and stir at 300rpm for 3 hours (after hydrolysis, the -SiOR group conversion rate is 85%). Add 12 parts of sodium polyacrylate with a molecular weight of 1 million to a 6% sodium chloride aqueous solution (instead of sodium bicarbonate), stir at 200rpm for 30 minutes until fully swollen, then let it stand and soak for 2 hours. After filtering to remove excess solution, microspheres with a water content of 28% are obtained. To the reactor, the hydrolyzed silane solution, 22 parts calcium nitrate (instead of calcium formate), 15 parts triethanolamine (instead of DEAIPA), and 4 parts sucrose were added in sequence. The heating and stirring devices were turned on, and the reaction temperature was controlled at 85°C (the traditional process temperature). The mixture was stirred at 400 rpm for 30 minutes until the viscosity of the mixture stabilized at 70 mPa·s. The microspheres were then added, and the stirring speed was reduced to 200 rpm. Stirring was continued for 15 minutes until the system was homogeneous and free of stratification. The heating device was turned off, and the product was naturally cooled to 25°C. It was then transferred to a sealed container and stored in a cool, dry environment with a humidity of 55%.

[0137] Specific working process

[0138] A titanate coupling agent is slowly added dropwise to a hydrolysis medium containing a 3:1 volume ratio of anhydrous ethanol and deionized water. The pH is adjusted to 4.0-5.0 with dilute hydrochloric acid. Hydrolysis is then carried out in a constant-temperature water bath at 35±2°C, stirring at 300 rpm for 3-5 hours, until the -SiOR group conversion rate is ≥90%. Sodium polyacrylate is added to a 5-8% aqueous sodium bicarbonate solution and stirred at 200 rpm for 30 minutes until it fully swells and absorbs the sodium bicarbonate. The solution is then allowed to soak for 2 hours to form a stable CO2-loaded structure. Excess solution is filtered to remove the resulting CO2-loaded microspheres with a water content of 25-30% and a particle size of 10-50 μm. The hydrolyzed titanate solution, calcium formate, DEAIPA, and sucrose were sequentially added to the reactor. The heating and stirring devices were turned on and stirred at 400 rpm at 60-70°C for 30 minutes until the mixture's viscosity stabilized at 80-120 mPa·s. CO2-loaded microspheres were then added and the stirring speed was reduced to 200 rpm. Stirring was continued for 15 minutes until the system was homogeneous and free of stratification. After the mixing reaction was complete, the heating device was turned off and the product was allowed to cool naturally to room temperature. It was then transferred to a sealed container and stored in a cool, dry environment.

[0139] The various technical features described in the above exemplary embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the various technical features in the above exemplary embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A cement mortar strengthener, characterized in that: Including the following raw materials in parts by mass: Active amines: 15-20 parts of diethanol monoisopropanolamine (DEAIPA); Coupling agent: 5-8 parts of titanate coupling agent; Inorganic salt: 20-25 parts of calcium formate; Functional carrier: 10-15 parts of sodium polyacrylate; Auxiliary agent: 3-5 parts of sucrose; 40-50 parts of deionized water.

2. A cement mortar strengthener according to claim 1, characterized in that: The titanate coupling agent is a TMC-TTS type titanate coupling agent.

3. A cement mortar strengthener according to claim 1, characterized in that: The molecular weight of the sodium polyacrylate is 800,000-1.2 million.

4. A cement mortar strengthener according to claim 1, characterized in that: The purity of the DEAIPA is ≥98%.

5. A method for preparing a cement mortar reinforcing agent, characterized in that: The following steps are involved: (1) Hydrolysis pretreatment of titanate coupling agent: mixing titanate coupling agent with anhydrous ethanol and deionized water for hydrolysis; (2) Sodium polyacrylate loaded with CO2 solution: Sodium polyacrylate is immersed in a sodium bicarbonate aqueous solution to form CO2 loaded microspheres; (3) Main mixing reaction: The hydrolyzed titanate solution is mixed with calcium formate, DEAIPA, and sucrose, and then CO2-loaded microspheres are added and mixed continuously; (4) Finished product packaging: sealed and packaged after cooling.

6. The method for preparing the cement mortar reinforcing agent according to claim 5, wherein: In step (1), the specific operation of the hydrolysis pretreatment of the titanate coupling agent is as follows: adding the titanate coupling agent dropwise to a mixture of anhydrous ethanol and deionized water (volume ratio 3:1), adjusting the pH to 4.0-5.0, stirring and hydrolyzing at 300 rpm at 35±2°C for 3-5 hours, and the conversion rate of -SiOR groups of the titanate coupling agent in the hydrolyzate is ≥90%.

7. The method for preparing the cement mortar reinforcing agent according to claim 6, wherein: The titanate coupling agent was added at a rate of 2 mL / min.

8. The method for preparing a cement mortar strengthener according to claim 5, wherein: In step (2), the specific operation of the sodium polyacrylate loaded CO2 solution is: adding sodium polyacrylate to a sodium bicarbonate aqueous solution with a concentration of 5-8%, stirring at 200 rpm for 30 minutes, and then standing and soaking for 2 hours, and filtering to obtain CO2 loaded microspheres (particle size 10-50 μm) with a water content of 25-30%.

9. The method for preparing a cement mortar reinforcing agent according to claim 5, wherein: In step (3), the specific operation of the main mixing reaction is: mixing the hydrolyzed titanate solution with calcium formate, DEAIPA, and sucrose, stirring at 400 rpm for 30 minutes at 60-70°C (the viscosity of the mixed solution is stabilized at 80-120 mPa·s), and then adding CO2-loaded microspheres and stirring at 200 rpm for 15 minutes until uniform and without stratification.

10. The method for preparing a cement mortar reinforcing agent according to claim 5, wherein: In step (4), the storage condition of the finished product packaging is a cool and dry environment (humidity ≤ 60%).

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