Cement mortar with carbon fixation and self-curing functions and preparation method thereof

Abstract

The application discloses cement mortar with carbon fixation and self-curing functions, and each component and weight percentage thereof include: cement 300-350 parts, modified lithium slag / nano titanium dioxide slurry 375-400 parts, and sand 1200-1350 parts; wherein each component in the modified lithium slag / nano titanium dioxide slurry and weight percentage thereof include: modified nano titanium dioxide liquid 240-260 parts and modified lithium slag powder 100-125 parts; the modified nano titanium dioxide liquid is amine-modified nano titanium dioxide liquid; and the modified lithium slag powder is lithium slag powder modified by polycarboxylic acid water-reducing component. The application firstly performs composite amine modification on nano titanium dioxide, modifies lithium slag powder by polycarboxylic acid water-reducing mother liquor, then stably combines the two, and introduces them into a cement mortar system, so that carbonation-hydration synergistic effect can be promoted to realize carbon fixation, effectively improve the overall performance of the cement mortar, and simplify curing conditions, and the application is suitable for popularization and application.

Description

Technical Field

[0001] The invention belongs to the technical field of building materials, and particularly relates to a cement mortar with carbon fixation and self-curing functions and a preparation method thereof. Background Art

[0002] As urbanization continues, higher carbon emission limits are being placed on the production and application of cement-based materials. Using low-energy, low-carbon alternatives, even those made from solid waste, is one of the most widely used carbon reduction technologies. However, the use of some solid waste materials may affect the long-term performance and quality of the substrate.

[0003] Strongly alkaline cementitious materials possess a certain natural advantage in carbonization (carbonization / mineralization). Their alkaline components react with CO2 to produce CaCO3 and H2O. Currently, carbonation curing techniques are commonly used to promote early carbonization of cementitious materials. However, this process often requires the creation of a sealed (high-pressure) gas chamber, which in turn results in a long carbonization cycle, limiting the development and application of carbonization in cementitious materials. Summary of the Invention

[0004] The main purpose of the present invention is to address the problems and shortcomings of the existing technology and provide a cement mortar with carbon fixation and self-curing functions. First, the nano-titanium dioxide dispersion is composite-modified with polyethyleneimine and dimethylolamine, and the lithium slag powder is modified with polycarboxylic acid water-reducing mother liquor. Then, the two are combined to promote the stable combination of nano-titanium dioxide particles and lithium slag powder, and to make the dissolved HCO3 - It can be stably adsorbed around lithium slag particles; then introduced into the cement mortar system, it can promote the carbonization-hydration synergistic effect, while fixing carbon, it can effectively improve the overall performance of the cement mortar, and is suitable for promotion and application.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] A cement mortar with carbon fixation and self-curing functions, wherein the components and their weight fractions include: 300-350 parts of cement, 375-400 parts of modified lithium slag / nano-titanium dioxide slurry, and 1200-1350 parts of sand; wherein the components and their weight fractions in the modified lithium slag / nano-titanium dioxide slurry include: 240-260 parts of modified nano-titanium dioxide liquid and 100-125 parts of modified lithium slag powder; the modified nano-titanium dioxide liquid is aminated modified nano-titanium dioxide liquid; and the modified lithium slag powder is lithium slag powder modified with a polycarboxylic acid water-reducing component.

[0007] In the above scheme, the components and their weight fractions in the modified nano-titanium dioxide liquid include: 6-9 parts of nano-titanium dioxide, 0.1-0.5 parts of polyethyleneimine, 5-10 parts of dimethanolamine, and 225-240 parts of water.

[0008] Further, the dimethyl ethanolamine is introduced in the form of dimethyl ethanolamine solution, and the preparation steps specifically include: mixing the weighed nano-titanium dioxide, polyethyleneimine, dimethyl ethanolamine solution and water (not including the water introduced in the dimethyl ethanolamine solution) and performing stirring treatment to obtain the modified nano-titanium dioxide solution. The composite modification of the nano-titanium dioxide by the polyethyleneimine and the dimethyl ethanolamine can effectively ensure the application effects of subsequent composite and carbonization modification.

[0009] In the above scheme, the molecular weight of the polyethyleneimine is 600-1800.

[0010] Further, the concentration of the dimethyl ethanolamine solution is 35-40 wt%.

[0011] Further, the stirring treatment is performed at a rate of 500-800 r / min for 10-15 min.

[0012] In the above scheme, the components and the weight fractions of the modified lithium slag powder include: 100 parts of dried lithium slag powder, 100-200 parts of alcohol solvent, 5-10 parts of polycarboxylic acid water-reducing mother liquor and 50-80 parts of water; and the preparation steps specifically include: mixing the weighed dried lithium slag powder and alcohol solvent, performing primary stirring treatment, adding the mixed solution of the weighed polycarboxylic acid water-reducing mother liquor and water, performing secondary stirring treatment, and drying the mixed material to obtain the modified lithium slag powder.

[0013] In the above scheme, the primary stirring treatment is performed at a rate of 500-700 r / min for 10-20 min, and the secondary stirring treatment is performed at a rate of 1000-1500 r / min for 40-60 min.

[0014] In the above scheme, the specific surface area of the lithium slag powder is 450-480 m 2 / kg, and the most probable pore size is 10-15 nm; and the main chemical components and the mass percentages thereof include: SiO2 63-66%, Al2O3 22-24% and CaO 2-4%.

[0015] In the above scheme, the dried lithium slag powder is dried at a temperature of 50-70℃ for 12-24 h, and then naturally cooled.

[0016] In the above scheme, the alcohol solvent can be anhydrous ethanol or the like. In the above scheme, the drying treatment is performed at a temperature of 100-105℃ for 20-24 h.

[0017] In the above scheme, the specific preparation steps of the modified lithium slag / nano-titanium dioxide slurry include: adding modified lithium slag powder to the modified nano-titanium dioxide liquid, adding a pH regulator to adjust the pH value to 8-10, stirring and carbonizing under the conditions of water bath ultrasound and introduction of CO2 gas, to obtain a uniform and stable modified lithium slag / nano-titanium dioxide slurry.

[0018] In the above solution, the pH adjuster can be an ammonia solution or the like, and its concentration is 20-25 wt%.

[0019] In the above scheme, the water bath ultrasound adopts a temperature of 30-40°C, a time of 40-60 minutes, and a frequency of 20-25 Hz.

[0020] In the above scheme, the flow rate of the CO2 gas is 1000-2000 sccm (the CO2 introduction time is 40-60 minutes); the purity of the CO2 gas is above 99.5 vol%.

[0021] In the above scheme, the stirring carbonization treatment adopts a rate of 100 to 200 r / min and a time of 40 to 60 minutes.

[0022] In the above solution, the cement is ordinary Portland cement; and the average particle size of nano-titanium dioxide is 1 to 5 nm.

[0023] In the above solution, the sand is natural sand with a fineness modulus of 2.6 to 2.8.

[0024] In the above solution, the water reduction rate of the polycarboxylic acid water-reducing concentrate is 40-45%.

[0025] The method for preparing the cement mortar having carbon fixation and self-curing functions comprises the following steps:

[0026] 1) Weighing the raw materials according to the proportions, wherein the raw materials and their weight proportions include: 300-350 parts of cement, 375-400 parts of modified lithium slag / nano-titanium dioxide slurry, and 1200-1350 parts of sand;

[0027] 2) first adding the modified lithium slag / nano-titanium dioxide slurry into a mixer, then adding cement, stirring at a low speed, then adding sand at the same stirring speed, stirring at a high speed once, stopping stirring and letting it stand, and then stirring at a high speed twice; thus, the cement mortar having carbon fixation and self-curing functions is obtained.

[0028] In the above scheme, the HCO3 of the modified lithium slag / nano-titanium dioxide slurry - The content is 23-25%.

[0029] In the above scheme, the low-speed stirring speed is 60-65 r / min, and the time is 30-60 s; the high-speed stirring speed is 120-125 r / min, wherein the first high-speed stirring time is 90-120 s, and the second high-speed stirring time is 60-90 s.

[0030] Further, the sand adding time is 30-60 s.

[0031] In the above scheme, the standing time after stopping stirring is 90-120 s.

[0032] Further, the curing conditions of the cement mortar include: normal temperature, and curing to room temperature.

[0033] Preferably, the relative humidity of the curing condition is 45-50%; the cement mortar does not need to be cured under the conventional humidity of more than 90% or water soaking condition; and the cement mortar has good self-curing performance.

[0034] The cement mortar prepared according to the above scheme has a 3d compressive strength of 31-34 MPa, a 28d compressive strength of 63-67 MPa, and an average porosity of less than 5.2%.

[0035] The principle of the present application is:

[0036] Compared with the prior art, the present application has the following beneficial effects:

[0037] 1) The present application first modifies the nano-titanium dioxide dispersion liquid by using polyethyleneimine and dimethanolamine, and modifies the lithium slag powder by using a polycarboxylic acid water reducing mother liquor; then combines the two, and the positively charged nano-titanium dioxide particles after amination treatment can be stably combined with the lithium slag modified by the polycarboxylic acid water reducing component and negatively charged; in addition, the polycarboxylic acid water reducing component as a superplasticizer can be adsorbed on the particle surface to play a good dispersion effect, effectively prevent particle agglomeration and other problems, and can control the water consumption in the base material design; the CO2 gas is introduced into the obtained modified lithium slag / nano-titanium dioxide slurry and combined with the optimized composite process, and the dissolved HCO3 - can be stably adsorbed around the lithium slag particles, thereby forming a stable HCO3 - carrier, and the modified composite solid waste admixture in the obtained modified lithium slag / nano-titanium dioxide slurry can stably carry HCO3 - After contacting with cement, it can promote the realization of carbonation-hydration synergistic reaction, which is conducive to the regulation of hydration environment (humidity, porosity), thereby achieving the effect of self-curing (especially for relatively dry curing conditions), and effectively improving the performance of the cement mortar.

[0038] 2) The present application uses a solid waste admixture containing a pore structure and low calcium and rich silicon as a carrier to carry HCO3 -And optimize its load stability, and use it to carry into the freshly mixed cement mortar, which is conducive to promoting the carbonization-hydration synergistic effect, while fixing carbon, improving the overall performance of the cement mortar; and the preparation cost involved is low, with significant economic and environmental benefits, suitable for promotion and application. DETAILED DESCRIPTION

[0039] In order to better understand the present invention, the content of the present invention is further illustrated below in conjunction with the examples, but the content of the present invention is not limited to the following examples.

[0040] In the following examples, the cement used is ordinary Portland cement with a P·O 42.5 content; the average particle size of nano-titanium dioxide is 5 nm; the specific surface area of ​​lithium slag powder is 460 m 2 / kg, the most probable pore diameter is 13nm; the main chemical components and their mass percentages are: SiO2 65.3%, Al2O3 23.4%, CaO 3.8%.

[0041] The sand used is natural sand.

[0042] The polycarboxylic acid water reducing concentrate used was provided by Jiangsu Subote New Materials Co., Ltd. -HW polycarboxylic acid water-reducing concentrate, with a water reduction rate of 42% and a solid content of 31%.

[0043] The polyethyleneimine used was provided by Shanghai Aladdin Biochemical Technology Co., Ltd. and had a molecular weight of 1800.

[0044] In the following examples, dimethanolamine was introduced in the form of a 40 wt % dimethanolamine aqueous solution.

[0045] Example 1

[0046] A cement mortar with carbon fixation and self-curing functions, the preparation method of which comprises the following steps:

[0047] 1) Preparation of modified lithium slag / nano-titanium dioxide slurry;

[0048] Mix 6 parts of nano-titanium dioxide, 0.1 parts of polyethyleneimine, 20 parts of dimethanolamine solution and 210 parts of water, and stir in a mechanical stirrer at a speed of 500 r / min for 10 minutes to obtain a modified nano-titanium dioxide liquid;

[0049] The lithium slag powder was dried at 50° C. for 18 hours and naturally cooled; 100 parts of the dried lithium slag powder was mixed with 100 parts of anhydrous ethanol and added to a beaker, and stirred at a speed of 500 r / min for 10 minutes using a mechanical stirrer, and then a mixture of 5 parts of polycarboxylic acid water-reducing mother liquor and 50 parts of water was added, and stirred at a speed of 1000 r / min for 40 minutes. The resulting mixed material was dried at 100° C. for 24 hours to obtain modified lithium slag powder;

[0050] 100 parts of modified lithium slag powder were added to 240 parts of modified nano-titanium dioxide liquid, and 20 wt% ammonia water was added to adjust the pH value of the resulting mixed solution to 8. The mixture was stirred at 100 r / min for 40 minutes under 30°C, 20 Hz water bath ultrasonic conditions. During this process, 99.5% pure CO2 gas was introduced into the slurry at a real-time flow rate of 1000 sccm. Thus, a uniform and stable modified lithium slag / nano-titanium dioxide slurry was obtained.

[0051] 2) Weigh 350 parts of cement, 375 parts of modified lithium slag / nano-titanium dioxide slurry, and 1350 parts of sand; first pour the modified lithium slag / nano-titanium dioxide slurry into a cement mortar mixer, then pour in the cement, stir for 30 seconds at a low speed (60 r / min), then add the sand within 30 seconds at the same stirring speed, and then stir at a high speed (120 r / min) for 90 seconds. After stopping stirring for 90 seconds, continue stirring at a high speed for 60 seconds at the same stirring speed; thus, the cement mortar with carbon fixation and self-curing functions is obtained.

[0052] Example 2

[0053] A cement mortar with carbon fixation and self-curing functions, the preparation method of which comprises the following steps:

[0054] 1) Preparation of modified lithium slag / nano-titanium dioxide slurry;

[0055] 7 parts of nano-titanium dioxide, 0.3 parts of polyethyleneimine, 25 parts of dimethanolamine solution and 215 parts of water were mixed and stirred in a mechanical stirrer at a speed of 700 r / min for 15 minutes to obtain a modified nano-titanium dioxide liquid;

[0056] The lithium slag powder was dried at 60°C for 12 hours and cooled naturally. 100 parts of the dried lithium slag powder was mixed with 150 parts of anhydrous ethanol and added to a beaker. A mechanical stirrer was used to stir the mixture at 600 r / min for 15 minutes. Then, a mixture of 8 parts of polycarboxylic acid water-reducing mother liquor and 70 parts of water was added and stirred at 1300 r / min for 50 minutes. The resulting mixture was dried at 105°C for 24 hours to obtain the modified lithium slag powder.

[0057] 120 parts of modified lithium slag powder were added to 250 parts of modified nano-titanium dioxide liquid, and 25 wt% ammonia water was added. The pH value of the resulting mixed solution was adjusted to 10, and stirring was continued at 150 r / min for 50 minutes under 35°C, 25 Hz water bath ultrasonic conditions. During this process, 99.5% pure CO2 gas was introduced into the slurry at a real-time flow rate of 1500 sccm; thus, a uniform and stable modified lithium slag / nano-titanium dioxide slurry was obtained.

[0058] 2) Weigh 350 parts of cement, 375 parts of modified lithium slag / nano-titanium dioxide slurry, and 1350 parts of sand; first pour the modified lithium slag / nano-titanium dioxide slurry into a cement mortar mixer, then pour in the cement, stir at a low speed (65 r / min) for 30 seconds, then add the sand within 30 seconds under the same stirring speed, and then stir at a high speed (125 r / min) for 90 seconds. After stopping stirring for 90 seconds, continue stirring at a high speed for 60 seconds under the same stirring speed; thus, the cement mortar with carbon fixation and self-curing functions is obtained.

[0059] Example 3

[0060] A cement mortar with carbon fixation and self-curing functions, the preparation method of which comprises the following steps:

[0061] 1) Preparation of modified lithium slag / nano-titanium dioxide slurry;

[0062] Mix 9 parts of nano-titanium dioxide, 0.5 parts of polyethyleneimine, 30 parts of dimethanolamine solution and 220 parts of water, and stir in a mechanical stirrer at a speed of 800 r / min for 15 minutes to obtain a modified nano-titanium dioxide liquid;

[0063] The lithium slag powder was dried at 60°C for 12 hours and cooled naturally. 100 parts of the dried lithium slag powder was mixed with 200 parts of anhydrous ethanol and added to a beaker. A mechanical stirrer was used to stir the mixture at 700 r / min for 20 minutes. Then, a mixture of 10 parts of polycarboxylic acid water-reducing mother liquor and 80 parts of water was added and stirred at 1500 r / min for 60 minutes. The resulting mixture was dried at 105°C for 24 hours to obtain the modified lithium slag powder.

[0064] To 260 parts of modified nano-titanium dioxide solution, 125 parts of modified lithium slag powder were added, along with 25 wt% ammonia water. The pH of the resulting mixed solution was adjusted to 10, and the mixture was stirred at 200 rpm for 60 minutes under 40°C, 25 Hz water bath ultrasonic conditions. During this process, 99.5% pure CO2 gas was introduced into the slurry at a real-time flow rate of 2000 sccm. This resulted in a uniform and stable modified lithium slag / nano-titanium dioxide slurry.

[0065] 2) Weigh 350 parts of cement, 375 parts of modified lithium slag / nano-titanium dioxide slurry, and 1350 parts of sand; first pour the modified lithium slag / nano-titanium dioxide slurry into a cement mortar mixer, then pour in the cement, stir at a low speed (65 r / min) for 30 seconds, then add the sand within 30 seconds under the same stirring speed conditions, and then stir at a high speed (125 r / min) for 90 seconds. After stopping stirring for 90 seconds, continue stirring at a high speed for 60 seconds under the same stirring speed conditions; thus, the cement mortar with carbon fixation and self-curing functions is obtained.

[0066] Comparative Example 1

[0067] A cement mortar, the preparation method of which comprises the following steps:

[0068] 1) Preparation of modified lithium slag / nano-titanium dioxide slurry;

[0069] 7 parts of nano-titanium dioxide, 26 parts of dimethylamine solution and 215 parts of water were mixed and stirred in a mechanical stirrer at a speed of 700 r / min for 15 minutes to obtain a modified nano-titanium dioxide liquid;

[0070] The lithium slag powder was dried at 60°C for 12 hours and cooled naturally. 100 parts of the dried lithium slag powder was mixed with 150 parts of anhydrous ethanol and added to a beaker. A mechanical stirrer was used to stir the mixture at a speed of 600 r / min for 15 minutes. Then, a mixture of 8 parts of polycarboxylic acid water-reducing mother liquor and 70 parts of water was added and stirred at a speed of 1300 r / min for 50 minutes. The resulting mixed material was dried at 105°C for 24 hours to obtain the modified lithium slag powder.

[0071] To 250 parts of modified nano-titanium dioxide solution, 120 parts of modified lithium slag powder were added, along with 25 wt% ammonia water. The pH of the resulting mixed solution was adjusted to 10, and the mixture was stirred at 150 rpm for 50 minutes under 35°C, 25 Hz water bath ultrasonic conditions. During this process, 99.5% pure CO2 gas was introduced into the slurry at a real-time flow rate of 1500 sccm. This resulted in a uniform and stable modified lithium slag / nano-titanium dioxide slurry.

[0072] 2) Weigh 350 parts of cement, 375 parts of modified lithium slag / nano-titanium dioxide slurry, and 1350 parts of sand; first pour the modified lithium slag / nano-titanium dioxide slurry into a cement mortar mixer, then pour in the cement, stir at a low speed (65 r / min) for 30 seconds, then add the sand within 30 seconds under the same stirring speed, and then stir at a high speed (125 r / min) for 90 seconds. After stopping stirring for 90 seconds, continue stirring at a high speed for 60 seconds under the same stirring speed; thus, the cement mortar with carbon fixation and self-curing functions is obtained.

[0073] Comparative Example 2

[0074] A cement mortar with carbon fixation and self-curing functions, the preparation method of which comprises the following steps:

[0075] 1) Preparation of modified lithium slag / nano-titanium dioxide slurry;

[0076] 7 parts of nano-titanium dioxide, 0.3 parts of polyethyleneimine, 25 parts of dimethanolamine solution and 215 parts of water were mixed and stirred in a mechanical stirrer at a speed of 700 r / min for 15 minutes to obtain a modified nano-titanium dioxide liquid;

[0077] The lithium slag powder was dried at 60°C for 12 hours and cooled naturally. 100 parts of the dried lithium slag powder was mixed with 150 parts of anhydrous ethanol and added to a beaker. A mechanical stirrer was used to stir the mixture at 600 r / min for 15 minutes. Then, a mixture of 8 parts of polycarboxylic acid water-reducing mother liquor and 70 parts of water was added and stirred at 1300 r / min for 50 minutes. The resulting mixture was dried at 105°C for 24 hours to obtain the modified lithium slag powder.

[0078] 120 parts of modified lithium slag powder were added to 250 parts of modified nano-titanium dioxide liquid, and the mixture was stirred at 150 r / min for 50 minutes under 35°C and 25 Hz water bath ultrasonic conditions. During this process, 99.5% pure CO2 gas was introduced into the slurry at a real-time CO2 flow rate of 1500 sccm; thus, a uniform and stable modified lithium slag / nano-titanium dioxide slurry was obtained.

[0079] 2) Weigh 350 parts of cement, 375 parts of modified lithium slag / nano-titanium dioxide slurry, and 1350 parts of sand; first pour the modified lithium slag / nano-titanium dioxide slurry into a cement mortar mixer, then pour in the cement, stir at a low speed (65 r / min) for 30 seconds, then add the sand within 30 seconds under the same stirring speed, and then stir at a high speed (125 r / min) for 90 seconds. After stopping stirring for 90 seconds, continue stirring at a high speed for 60 seconds under the same stirring speed; thus, the cement mortar with carbon fixation and self-curing functions is obtained.

[0080] Comparative Example 3

[0081] A cement mortar, the preparation method of which comprises the following steps:

[0082] 1) Mix 7 parts of nano-titanium dioxide, 0.3 parts of polyethyleneimine, 25 parts of dimethanolamine solution and 215 parts of water, and stir in a mechanical stirrer at a speed of 700 r / min for 15 minutes to obtain a modified nano-titanium dioxide solution;

[0083] 120 parts of dried lithium slag powder were added to 250 parts of a modified nano-titanium dioxide solution, and 25 wt% ammonia water was added. The pH value of the resulting mixed solution was adjusted to 10, and the mixture was stirred at 150 r / min for 50 minutes under 35°C, 25 Hz water bath ultrasonic conditions. During this process, 99.5% pure CO2 gas was introduced into the slurry at a real-time flow rate of 1500 sccm; thus, a modified lithium slag / nano-titanium dioxide slurry was obtained.

[0084] 2) Weigh 350 parts of cement, 375 parts of modified lithium slag / nano-titanium dioxide slurry, 1350 parts of sand, and 5 parts of polycarboxylate water reducer; first pour the modified lithium slag / nano-titanium dioxide slurry and the polycarboxylate water reducer into a cement mortar mixer, then pour the cement, stir at a low speed (65 r / min) for 30 seconds, then add the sand within 30 seconds under the same stirring speed, and then stir at a high speed (125 r / min) for 90 seconds. After stopping stirring for 90 seconds, continue stirring at a high speed for 60 seconds under the same stirring speed; thus, the cement mortar with carbon fixation and self-curing functions is obtained.

[0085] The carbon fixation capacity of the modified lithium slag slurry prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was tested, and the kit steps included:

[0086] The modified lithium slag slurry is filtered, dried, and HCO3 - Content determination, the test method uses a calcium carbonate content tester, that is, through HCl and HCO3 - The reaction collects the pressure change caused by the generated CO2 and converts it into HCO3 - content.

[0087] Table 1 Carbon fixation capacity of modified lithium slag / nano-titanium dioxide slurry (%)

[0088]

[0089] It can be found that the carbon fixation rate of the modified lithium slag / nano-titanium dioxide slurry obtained in Examples 1 to 3 is about 25%, while the carbon fixation capacity of Comparative Examples 1 to 3 is significantly reduced or even lacks carbon fixation capacity due to the low single amination modification effect of nano-titanium dioxide, the pH value of the modified lithium slag powder is not alkaline adjusted, and the lithium slag powder is not modified with a polycarboxylic acid water-reducing component.

[0090] The compressive strength development of the cement mortars prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was tested.

[0091] A 40×40×160 mm test block was prepared. After 1 day, the block was removed from the mold and placed in an environment of 20±2°C and 50% relative humidity. The compressive strength of the test block was tested 3 days and 28 days after molding. The results are shown in Table 2:

[0092] Table 2 Compressive strength (MPa) of cement mortar test blocks obtained in each embodiment and comparative example

[0093]

[0094] It can be found that the 3d and 28d compressive strengths of the cement mortar specimens obtained in Examples 1 to 3 are higher than those in Comparative Example 1. This is mainly because in the hydration process of Examples 1 to 3, a hydration-carbonization synergistic effect occurs, which can effectively promote the strength development of the cement mortar, while the cement mortars described in Comparative Examples 1 and 3 develop strength more slowly in a relatively dry environment; in Comparative Example 2, since the modified lithium slag powder is not alkaline adjusted, its addition to the cement mortar will have a certain negative impact on the hydration of the cement.

[0095] The 28-day porosity changes of the cement mortar test blocks prepared in Examples 1 to 3 were tested. Mercury intrusion porosimetry was performed on samples from the center of each test block after the 28-day compressive strength test to measure porosity. The results are shown in Table 3.

[0096] Table 3 28d average porosity of cement mortar test blocks obtained in each embodiment and comparative example (%)

[0097]

[0098] It can be found that the porosity inside the cement mortar test blocks prepared in Examples 1 to 3 is within 5%, which is much lower than that in Comparative Examples 1, 2, and 3. The main reason is the hydration-carbonization synergistic effect that can occur in the cement mortar systems obtained in Examples 1 to 3 (especially under relatively dry curing conditions), which also confirms to a certain extent the excellent compressive strength development of Examples 1 to 3.

[0099] Obviously, the above embodiments are merely examples for illustrative purposes and are not intended to limit the implementation methods. Those skilled in the art will readily appreciate that other variations or modifications based on the above descriptions are possible. It is not necessary and impossible to enumerate all implementation methods here. However, any obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A cement mortar with carbon fixation and self-curing functions, characterized in that: The components and their weight fractions include: 300-350 parts of cement, 375-400 parts of modified lithium slag / nano-titanium dioxide slurry, and 1200-1350 parts of sand; wherein the components and their weight fractions in the modified lithium slag / nano-titanium dioxide slurry include: 240-260 parts of modified nano-titanium dioxide liquid and 100-125 parts of modified lithium slag powder; the modified nano-titanium dioxide liquid is an aminated modified nano-titanium dioxide liquid; the modified lithium slag powder is lithium slag powder modified with a polycarboxylic acid water-reducing component; The modified nano-titanium dioxide solution comprises the following components and their weight fractions: 6-9 parts of nano-titanium dioxide, 0.1-0.5 parts of polyethyleneimine, 5-10 parts of dimethanolamine, and 220-240 parts of water. The specific preparation steps of the modified lithium slag / nano-titanium dioxide slurry include: adding modified lithium slag powder to the modified nano-titanium dioxide liquid, adjusting the pH value to 8-10, stirring and carbonizing under the conditions of water bath ultrasound and introduction of CO2 gas, so as to obtain a uniform and stable modified lithium slag / nano-titanium dioxide slurry.

2. The cement mortar according to claim 1, characterized in that The modified lithium slag powder comprises the following components and their weight fractions: 100 parts of dry lithium slag powder, 100-200 parts of alcohol solvent, 5-10 parts of polycarboxylic acid water-reducing mother liquor, and 50-80 parts of water.

3. The cement mortar according to claim 2, characterized in that: The specific surface area of ​​lithium slag powder is 450~480m 2 / kg, the most probable pore diameter is 10~15nm; the main chemical composition and its mass percentage include: SiO263~66%, Al2O322~24%, CaO 2~4%.

4. The cement mortar according to claim 2, characterized in that The polycarboxylic acid water-reducing concentrate has a water reduction rate of 40-45%.

5. The cement mortar according to claim 1, characterized in that The water bath ultrasound uses a temperature of 30-40° C., a frequency of 20-25 Hz, and an ultrasound time of 40-60 min.

6. The cement mortar according to claim 1, characterized in that The flow rate of the CO2 gas is 1000~2000sccm; the purity of the CO2 gas is above 99.5vol%.

7. The cement mortar according to claim 1, characterized in that The cement is ordinary Portland cement; the average particle size of nano titanium dioxide is 1-5 nm; and the sand is natural sand with a fineness modulus of 2.6-2.

8.

8. The method for preparing the cement mortar with carbon fixation and self-curing functions according to any one of claims 1 to 7, characterized in that: The steps include: 1) Weigh the raw materials according to the proportions, including: 300-350 parts of cement, 375-400 parts of modified lithium slag / nano-titanium dioxide slurry, and 1200-1350 parts of sand; 2) first adding the modified lithium slag / nano-titanium dioxide slurry into a mixer, then adding cement and stirring at a low speed, then adding sand at the same stirring speed and stirring at a high speed once, stopping stirring and letting it stand, and then stirring at a high speed a second time; thus, the cement mortar having carbon fixation and self-curing functions is obtained.

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