A cement mortar composite with copper hydroxide nanoarrays and its preparation method

Abstract

The present application relates to the technical field of cement mortar, and more specifically, to a cement mortar composited with a copper hydroxide nanoarray and a preparation method thereof. The cement mortar is prepared by mechanically mixing and stirring cement, fine sand, water, and a copper hydroxide nanoarray as raw materials; wherein the water-cement ratio of the mortar is 0.6-0.75, the mass ratio of cement to fine sand is 1:3-3.9, and the mass fraction of the copper hydroxide nanoarray is 0.5-2%. The copper hydroxide nanoarray is grown in situ on foamed copper by a hydrothermal method, which is clean and pollution-free. The copper hydroxide nanoarray can improve the mechanical properties of the mortar and has a rapid effect on the early compressive strength and flexural strength of the cement mortar.

Description

Technical Field

[0001] The present application relates to the technical field of cement mortar, and more specifically, to a copper hydroxide nano-array composite cement mortar and a preparation method thereof. Background Art

[0002] Cement is one of the most widely used building materials today, widely used in projects such as housing and bridge construction. However, its development is limited by shortcomings such as low mechanical strength and poor performance of cement-based materials. To overcome these shortcomings, some researchers have incorporated materials such as polypropylene fibers and steel fibers. However, the addition of materials such as steel fibers has failed to improve the microstructure of cement-based materials or inhibit the development of microcracks in cement.

[0003] In recent years, nanomaterials such as carbon nanotubes, carbon fibers, and graphene have attracted considerable attention due to their exceptional strength and excellent performance. They are being widely researched and applied to improve the properties of composite materials. Consequently, numerous researchers have begun investigating how to modify the microscopic geometry of cementitious materials by incorporating nanomaterials, thereby enhancing their mechanical properties and electrical conductivity.

[0004] Single-phase metal oxides / hydroxides have serious limitations due to their inherent properties, such as low conductivity and poor stability, and have not yet been effectively developed. Currently, traditional concrete has limitations such as low mechanical strength and poor workability. Summary of the Invention

[0005] This disclosure provides a cement mortar composited with a copper hydroxide nanoparticle array and its preparation method. The copper hydroxide nanoparticle arrays are grown in situ on copper foam via a hydrothermal method, resulting in a clean and pollution-free process. The copper hydroxide nanoparticle arrays also improve the mechanical properties of the mortar, rapidly enhancing its early compressive and flexural strengths. Furthermore, the copper hydroxide nanoparticle arrays exhibit excellent electrical conductivity and chemical stability, enabling them to work synergistically with the mortar.

[0006] In a first aspect, the present disclosure provides a cement mortar composited with a copper hydroxide nanoarray and a preparation method thereof. The cement mortar is prepared by mechanically mixing and stirring cement, fine sand, water, and copper hydroxide nanoarrays as raw materials; wherein the mortar has a water-cement ratio of 0.6-0.75, a mass ratio of cement to fine sand of 1:3-3.9, and a mass fraction of the copper hydroxide nanoarrays of 0.5-2%.

[0007] Copper hydroxide nanoarrays are a new type of nanomaterial that are in-situ grown on copper-based materials through hydrothermal methods and oxidation reactions. They can provide a huge specific surface area and a high number of nucleation sites. These two factors have an important influence on the effect of nanomaterials on cement hydration reactions. In addition, due to the presence of oxygen-containing groups, they have good hydrophilicity, which enables them to be evenly dispersed in the mortar. Copper hydroxide nanoarrays can improve the mechanical properties of the mortar and rapidly enhance the early compressive strength and flexural strength of the cement mortar. At the same time, copper hydroxide nanoarrays have good hydrophilicity and chemical stability, and can work synergistically with the mortar, which is in line with the design concept of green smart buildings. Copper hydroxide nanoarrays are in-situ grown on foamed copper and have a higher specific surface area than ordinary nanomaterials.

[0008] In a second aspect, the present disclosure provides a method for preparing a cement mortar composited with a copper hydroxide nanoparticle array, the preparation steps of the mortar comprising:

[0009] S1: Weigh cement, water, fine sand, and copper hydroxide nanoarrays, and mix the copper hydroxide nanoarrays with 10% water to prepare a uniform dispersion;

[0010] S2: Cement, copper hydroxide nanoarray dispersion, and remaining water were added to a mixing pot and stirred at a low speed. Fine sand was evenly added during the stirring period. After thorough stirring, the mixture was allowed to stand for 90 seconds. The mixer was then switched to a high-speed stirring mode to prepare cement mortar.

[0011] Copper hydroxide nanoarrays are evenly dispersed in water, and then the uniform copper hydroxide nanoarray dispersion is added to cement mortar as an additive. The prepared cement mortar has a dense structure after curing and significantly improved early mechanical strength.

[0012] Copper hydroxide nanoarrays are rod-shaped crystals that can be embedded in cement cracks. When the cracks open, friction is generated. The copper hydroxide nanoarrays can improve the structural transition zone of the cement paste and increase the mechanical friction with the hydration products through bridging action, thereby promoting a tighter connection between the hydration products.

[0013] Preferably, the method for preparing the copper hydroxide nanoarray comprises the following steps:

[0014] A: Pretreatment of copper foam: The copper foam was cut and then ultrasonically treated with HCl solution, acetone, ethanol and deionized water in sequence, and then fully dried in a vacuum drying oven;

[0015] B: Soaking: Add NaOH to deionized water, wait for it to be fully dissolved and cooled, then add (NH4)2S2O8 and stir to mix the solution evenly to prepare a mixed solution, and soak the pretreated copper foam in the mixed solution;

[0016] C: The beaker was shaken appropriately to form a light blue layer of Cu(OH)2 on the surface of the foam copper. The foam copper was finally taken out and washed with ethanol and deionized water respectively, and the product was finally obtained after drying.

[0017] Preferably, in S2, cement, copper hydroxide nanoarray dispersion and remaining water are added to a stirring pot and stirred at a low speed of 60-70 rpm for 60-80 seconds.

[0018] Preferably, the time for uniformly adding fine sand during stirring in S2 starts from the second 30 seconds of low-speed stirring.

[0019] Preferably, the stirrer in S2 is adjusted to a high speed of 120-140 rpm and stirred for 60-80 seconds.

[0020] Preferably, the copper hydroxide nanoarray is copper hydroxide nanorod array powder.

[0021] Preferably, the particle size of the fine sand is in the range of 0.25-0.5 mm.

[0022] In summary, this application has the following beneficial effects:

[0023] 1. Since copper hydroxide nanoarrays are uniformly dispersed in water in this application, and the uniform copper hydroxide nanoarray dispersion is then added to cement mortar as an additive, the prepared cement mortar has a dense structure after curing and significantly improved early mechanical strength;

[0024] 2. The copper hydroxide nano-array composite cement mortar in this application has been tested for conductivity, and its conductivity has been greatly improved, which significantly improves the working performance of cement mortar and overcomes the limitations of traditional concrete.

[0025] 3. The copper hydroxide nanoarray used in this application is in-situ grown on foam copper through a hydrothermal method. The production process is clean and environmentally friendly, and is in line with the design concept of green smart buildings.

[0026] It should be understood that the foregoing general description and the following detailed description are merely exemplary and explanatory and are not intended to limit the scope of protection of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] 1. Figure 1 is a scanning electron microscope image of the copper hydroxide nanoarray used in this application;

[0028] 2. Figure 2 This is a graph showing the change in compressive strength of the cement mortar prepared in this application after curing for 28 days as a function of the copper hydroxide nanoarray dosage;

[0029] 3. Figure 3This is a graph showing the change in flexural strength of the cement mortar prepared in this application after curing for 28 days as a function of the copper hydroxide nanoarray dosage;

[0030] 4. Figure 4 This is a microstructure diagram of cement mortar with different dosages of copper hydroxide nanoarrays in this application. DETAILED DESCRIPTION

[0031] The present application is further described in detail below with reference to the examples. It is particularly noted that if no specific conditions are specified in the following examples, the reactions are carried out according to conventional conditions or the conditions recommended by the manufacturer. Unless otherwise specified, the raw materials used in the following examples can be obtained from common commercial sources.

[0032] The cement in this application is Portland cement (PO42.5R);

[0033] The fine sand in this application is geotechnical standard sand.

[0034] Preparation examples of raw materials and / or intermediates

[0035] Preparation Example 1

[0036] A method for preparing a copper hydroxide nanoarray comprises the following steps:

[0037] A: Pretreatment of foam copper: Cut the foam copper into pieces with the size of (0.5×0.5cm 2 ), and then ultrasonically treated with HCl solution, acetone, ethanol and deionized water in sequence, and then fully dried in a vacuum drying oven;

[0038] B: Soaking: Add NaOH to deionized water, wait for it to be fully dissolved and cooled, then add (NH4)2S2O8 and stir to mix the solution evenly to prepare a mixed solution, and soak the pretreated copper foam in the mixed solution;

[0039] C: The beaker was shaken appropriately to form a light blue layer of Cu(OH)2 on the surface of the foam copper. The foam copper was finally taken out and washed with ethanol and deionized water respectively, and the product was finally obtained after drying.

[0040] Example

[0041] Example 1

[0042] A method for preparing a copper hydroxide nanoarray composite cement mortar is disclosed. The cement mortar is prepared by mechanically mixing and stirring cement, fine sand, water, and the copper hydroxide nanoarray prepared in Preparation Example 1. The water-cement ratio of the mortar is 0.75, the mass ratio of cement to fine sand is 1:3.9, and the copper hydroxide nanoarray content is 0.5% of the cement solids mass. The mortar preparation process includes weighing cement, water, fine sand, and copper hydroxide nanoarrays according to the aforementioned proportions. The copper hydroxide nanoarrays are mixed with 10% water to prepare a uniform dispersion. The cement, copper hydroxide nanoarray dispersion, and remaining water are then added to a mixing pot and stirred at a low speed of 62 rpm for 30 seconds. Fine sand is then evenly added at the beginning of the second 30 seconds of low-speed stirring. After thorough stirring, the mixture is allowed to stand for 90 seconds. The mixer is then switched to a high speed of 125 rpm and stirred for 60 seconds to prepare the cement mortar.

[0043] Example 2

[0044] A method for preparing a copper hydroxide nanoarray composite cement mortar is disclosed. The cement mortar is prepared by mechanically mixing and stirring cement, fine sand, water, and the copper hydroxide nanoarrays prepared in Preparation Example 1. The mortar has a water-to-cement ratio of 0.75, a cement-to-fine sand mass ratio of 1:3.9, and a copper hydroxide nanoarray content of 1% of the cement solids mass. The mortar preparation process involves weighing cement, water, fine sand, and copper hydroxide nanoarrays according to the aforementioned proportions. The copper hydroxide nanoarrays are then mixed with 10% water to prepare a uniform dispersion. The cement, copper hydroxide nanoarray dispersion, and remaining water are then added to a mixing pot and stirred at a low speed of 62 rpm for 30 seconds. At the beginning of the second 30 seconds of low-speed stirring, fine sand is evenly added. After thorough stirring, the mixture is allowed to stand for 90 seconds. The mixer is then switched to a high speed of 125 rpm for 60 seconds to prepare the cement mortar.

[0045] Example 3

[0046] A method for preparing a copper hydroxide nanoarray composite cement mortar is disclosed. The cement mortar is prepared by mechanically mixing and stirring cement, fine sand, water, and the copper hydroxide nanoarray prepared in Preparation Example 1. The water-cement ratio of the mortar is 0.75, the mass ratio of cement to fine sand is 1:3.9, and the copper hydroxide nanoarray content is 1.5% of the cement solids mass. The mortar preparation process includes weighing cement, water, fine sand, and copper hydroxide nanoarrays according to the above proportions. The copper hydroxide nanoarrays are mixed with 10% water to prepare a uniform dispersion. The cement, copper hydroxide nanoarray dispersion, and remaining water are then added to a mixing pot and stirred at a low speed of 62 rpm for 30 seconds. At the beginning of the second 30 seconds of low-speed stirring, fine sand is evenly added. After thorough stirring, the mixture is allowed to stand for 90 seconds. The mixer is then switched to a high speed of 125 rpm and stirred for 60 seconds to prepare the cement mortar.

[0047] Example 4

[0048] A method for preparing a copper hydroxide nanoarray composite cement mortar is disclosed. The cement mortar is prepared by mechanically mixing and stirring cement, fine sand, water, and the copper hydroxide nanoarray prepared in Preparation Example 1. The mortar has a water-to-cement ratio of 0.75, a cement-to-fine sand mass ratio of 1:3.9, and a copper hydroxide nanoarray content of 2% of the cement solids mass. The mortar preparation process involves weighing cement, water, fine sand, and copper hydroxide nanoarrays according to the aforementioned proportions. The copper hydroxide nanoarrays are then mixed with 10% water to prepare a uniform dispersion. The cement, copper hydroxide nanoarray dispersion, and remaining water are then added to a mixing pot and stirred at 62 rpm for 30 seconds. At the beginning of the second 30 seconds of low-speed stirring, fine sand is evenly added. After thorough stirring, the mixture is allowed to stand for 90 seconds. The mixer is then switched to high speed and stirred at 125 rpm for 60 seconds to prepare the cement mortar.

[0049] Comparative Example

[0050] Comparative Example 1

[0051] A method for preparing a copper hydroxide nanoarray composite cement mortar is disclosed. The cement mortar is prepared by mechanically mixing cement, fine sand, and water. The water-to-cement ratio of the mortar is 0.75, and the mass ratio of cement to fine sand is 1:3.9. The mortar preparation process involves weighing cement, water, and fine sand according to the aforementioned proportions. The cement and water are then added to a mixing pot and stirred at a low speed of 62 rpm for 30 seconds. At the beginning of the second 30 seconds of low-speed stirring, fine sand is evenly added. After thorough stirring, the mixture is allowed to stand for 90 seconds. The mixer is then switched to a high speed of 125 rpm and stirred for 60 seconds to prepare the cement mortar.

[0052] The specific proportion data of Examples 1-4 and the comparative group are shown in Table 1. The cement mortars prepared in Examples 1-4 and the comparative group were poured into molds with dimensions of 15 mm × 15 mm × 80 mm and 20 mm × 20 mm × 20 mm, respectively, to test the flexural strength (the test pieces cut after the flexural strength test were used for the compressive strength test) and electrical conductivity of the cement mortar. After 24 hours, the test pieces were removed from the molds and cured in an environment of 20 ± 1 ° C and 95% relative humidity to 3 days, 7 days, 14 days, and 28 days for testing. With reference to the test standard "Test Method for Strength of Cement Mortar (ISO Method)" (GB17671-1999), the compressive strength and flexural strength of the cement mortar were tested, and the electrical conductivity of the cement mortar was tested using the dipole method. Compressive and flexural strengths were tested using a 5982 universal testing machine, with a compressive loading rate of 0.5 mm / min and a flexural loading rate of 0.2 mm / min. Three samples were tested for flexural strength, and six samples were tested for compressive strength for each mix ratio. Electrical conductivity was tested using a digital multimeter (Baogong MT-1280-C) connected to a 24V AC power supply.

[0053] Table 1

[0054]

[0055] (1) Mechanical strength

[0056] Table 2 shows the mechanical properties of cement mortar with different dosages (0wt%, 0.5wt%, 1wt%, 1.5wt%, 2wt%) of copper hydroxide nanoarrays at different curing ages (3d, 7d, 28d). Figure 2 and Figure 3 The results show the changing trends of the compressive strength and flexural strength of cement mortar with the addition of copper hydroxide nanoarray and curing age. As the curing age increases, the compressive strength and flexural strength of cement mortar increase. In addition, compared with the control group, the compressive strength and flexural strength of cement mortar with copper hydroxide nanoarray are also significantly improved. As the addition amount of copper hydroxide nanoarray changes, the growth rate of the mechanical strength of the mortar is also different. When the addition amount is 0.5wt%, the compressive strength and flexural strength of cement mortar are greatly improved; when the addition amount is greater than 0.5wt%, the increase in the compressive strength and flexural strength of cement mortar shows a downward trend. Among them, when the curing age is 28d and the addition amount is 0.5wt%, the compressive strength and flexural strength of cement mortar increase by 50.3% and 41.23% respectively, reaching the maximum value. Therefore, copper hydroxide nanoarray can improve the mechanical properties of cement mortar. After analysis, the reasons include the following three:

[0057] Copper hydroxide nanoarrays have a high specific surface area and can provide more nucleation sites, promoting the generation and development of cement hydration products;

[0058] Due to its special size advantage, copper hydroxide nanoarrays can be used as filling particles to fill the pore space inside the mortar, making the mortar microstructure more compact;

[0059] Copper hydroxide nanoarrays can improve the structural transition zone of cement paste by increasing the mechanical friction with hydration products through bridging effect, thereby promoting a tighter connection between the hydration products.

[0060] Table 2

[0061]

[0062] (2) Micro-testing

[0063] The microstructure of cement-based composites controls their macroscopic behavior. Therefore, the present invention uses scanning electron microscopy to perform microscopic characterization of copper hydroxide nanoarrays and copper hydroxide nanoarray composite cement mortar.

[0064] Figure 1 The copper hydroxide nanoarrays exhibit a large number of rod-shaped crystals on their surface, possessing extremely high surface activation energy, capable of supporting a large number of nucleation sites for hydration products, such as calcium silicate hydrate. Furthermore, their surface is rich in oxygen-containing functional groups, which facilitate their uniform dispersion in the mortar solution, promoting the dense development of more hydration products and improving their density. Furthermore, their unique rod-shaped crystals can tightly connect hydration products, such as calcium silicate hydrate, through a bridging effect, thereby improving the microstructure of the cement mortar. Figure 4 The microstructure of cement mortar with different copper hydroxide nanoparticles and different dosages after curing for 28 days was tested by scanning electron microscopy. Figure 4 The dosage of copper hydroxide nanoarrays in (a), (b), and (c) is 0wt%, 0.5wt%, and 2wt%, respectively. The figure clearly shows that the cement mortar with a dosage of 0wt% contains a large number of pores, and the hydration products are irregularly arranged in a flocculent manner. The hydration products are sparse and loose, and are not tightly connected to each other. When the dosage is 0.5wt%, the figure shows that the internal pores of the cement mortar are significantly reduced, the needle-shaped crystals are compactly arranged and plate-like, and the structural density is improved. The copper hydroxide nanoarrays have significantly improved the microstructure of the cement mortar. When the dosage is increased to 2wt%, it is obvious from the figure that the degree of hydration is significantly reduced compared to the 0.5wt% dosage, and needle-shaped crystals and plate-like crystals coexist in the cement mortar. The results show that copper hydroxide nanoarrays have a regulatory effect on the hydration reaction of cement mortar, improving the density of the mortar hydration products, and thus enhancing the mechanical properties of cement-based materials.

[0065] The above description is merely an exemplary embodiment of the present disclosure, but the scope of protection of the present disclosure is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present disclosure should be included in the scope of protection of the present disclosure. Therefore, the scope of protection of the present disclosure should be based on the scope of protection of the claims.

Claims

1. A copper hydroxide nano-array composite cement mortar, characterized in that: The cement mortar is prepared by mechanically mixing and stirring cement, fine sand, water, and copper hydroxide nanoarrays as raw materials; wherein the water-cement ratio of the cement mortar is 0.6-0.75, the mass ratio of cement to fine sand is 1:3-3.9, and the copper hydroxide nanoarray is copper hydroxide nanorod array powder, and the mass fraction of the copper hydroxide nanoarray is 0.5%.

2. The method for preparing a copper hydroxide nano-array composite cement mortar according to claim 1, characterized in that: The preparation steps of the mortar include: S1: Weigh cement, water, fine sand, and copper hydroxide nanoarrays, and mix the copper hydroxide nanoarrays with 10% water to prepare a uniform dispersion; S2: Cement, copper hydroxide nanoarray dispersion, and remaining water were added to a mixing pot and stirred at a low speed. Fine sand was evenly added during the stirring period. After thorough stirring, the mixture was allowed to stand for 90 seconds. The mixer was then switched to a high speed to prepare a cement mortar. The method for preparing the copper hydroxide nanoarray comprises the following steps: A: Pretreatment of copper foam: The copper foam was cut and then ultrasonically treated with HCl solution, acetone, ethanol and deionized water in sequence, and then fully dried in a vacuum drying oven; B: Soaking: Add NaOH to deionized water, wait for it to be fully dissolved and cooled, then add (NH4)2S2O8 and stir to mix the solution evenly to prepare a mixed solution, and soak the pretreated copper foam in the mixed solution; C: Shake the beaker appropriately, and a light blue layer of Cu(OH) will form on the surface of the foam copper. 2， Finally, the foam copper is taken out, washed with ethanol and deionized water respectively, and dried to finally obtain the product.

3. The method for preparing a copper hydroxide nano-array composite cement mortar according to claim 2, characterized in that: In the step S2, cement, copper hydroxide nanoarray dispersion and remaining water are added to a stirring pot and stirred at a low speed of 60-70 rpm for 60-80 seconds.

4. The method for preparing a copper hydroxide nano-array composite cement mortar according to claim 2, characterized in that: The time for uniformly adding fine sand during the stirring in S2 is starting from the second 30s of low-speed stirring.

5. The method for preparing a copper hydroxide nano-array composite cement mortar according to claim 2, characterized in that: The stirrer in S2 was adjusted to high speed and stirred at 120-140 rpm for 60-80 seconds.

6. The method for preparing a copper hydroxide nano-array composite cement mortar according to claim 2, characterized in that: The particle size of the fine sand is in the range of 0.25-0.5 mm.

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