A pre-dispersing device for nanomaterial modified cement

Abstract

The application discloses a kind of pre-dispersing devices for nanomaterial modified cement, belong to cement material science and engineering technical field.The device includes ultrasonic dispersion probe, dispersion container, magnetic stirring rotor and magnetic heating stirrer.Dispersion container is set on magnetic heating stirrer, magnetic stirring rotor is placed in dispersion container, and ultrasonic dispersion probe is inserted into nanomaterial dispersion liquid in dispersion container.In use, circulating flow field is formed by magnetic stirring, and the agglomeration of nanomaterial is destroyed by ultrasonic effect, to realize the uniform pre-dispersion of nanomaterial before entering cement system.The application can reduce the agglomeration degree of nanomaterial, improve its distribution uniformity and effective reaction area in cement paste, enhance the nucleation, filling and reaction activity of nanomaterial, and is suitable for nanosilica, nanoalumina, nanocalcium carbonate, carbon nanotube, graphene oxide and other nanomaterial modified cement system.

Description

Technical Field

[0001] This invention relates to the field of cement materials science and engineering technology, specifically to a pre-dispersion device for nanomaterial-modified cement. This device and method are used to pre-disperde nanomaterials before mixing them with cement through the synergistic effect of ultrasonic dispersion and magnetic stirring. This invention can be used in the preparation processes of nano-silica-modified cement, cement-cured heavy metals, cement-based composite materials, and other functionalized cement-based materials. Background Technology

[0002] Nanomaterials, due to their small particle size, large specific surface area, high surface activity, and strong reactivity, have been widely used in the modification of cement-based materials in recent years. Taking nano-silica as an example, it can exert nucleation, pore-filling, and pozzolanic reaction effects in cement systems. On the one hand, nano-silica can provide heterogeneous nucleation sites for cement hydration products, promoting the hydration of cement clinker minerals; on the other hand, nano-silica can undergo a secondary reaction with calcium hydroxide generated during cement hydration, producing more CSH gel, thereby improving the density, strength, durability, and impermeability of cement-based materials. Furthermore, in cement-cured heavy metal systems, the CSH gel and dense porous structure promoted by nano-silica can enhance the adsorption, precipitation, complexation, structural fixation, and physical encapsulation of heavy metals, thereby reducing the migration and leaching risks of heavy metals.

[0003] However, nanomaterials exhibit significant agglomeration problems in practical applications. Due to the high surface energy of nanoparticles, they easily form aggregates under van der Waals forces, electrostatic interactions, and capillary action. Agglomerated nanomaterials are difficult to disperse uniformly in cement paste, leading to a reduction in their effective specific surface area, decreased reactivity, and even the formation of localized weak zones within the cement matrix. Especially when the nanomaterial content is high, the water-cement ratio is low, or the paste viscosity is high, ordinary mechanical stirring is insufficient to effectively break up the nanomaterial aggregates, thus affecting the modification effect.

[0004] Chinese patent document CN103664028A discloses a method for dispersing nano-silica powder in cement-based materials. This method uses a water-reducing agent as a dispersant. First, the water-reducing agent is dissolved in water to form a dispersion. Then, nano-silica powder is added to prepare a nano-silica dispersion, which is then mixed with cement, sand, admixtures, etc., thereby improving the dispersion efficiency of nano-silica in cement-based materials. However, the water-reducing agent added in this method will additionally affect the hydration process of cement.

[0005] Chinese patent document CN108947290A discloses a method for improving the pore structure of cement-based materials using highly dispersible nano-silica. This method disperses nano-silica using a polycarboxylic acid modifier. However, this method has a certain impact on the cement hydration process and does not significantly improve physical agglomeration.

[0006] Therefore, it is necessary to design a pre-dispersion device for nanomaterial-modified cement to ensure that the nanomaterials are fully dispersed before entering the cement system. By improving the dispersion uniformity of nanomaterials in the dispersion medium before cement mixing, the actual efficiency of nanomaterials can be effectively improved, enhancing their effect on cement hydration reaction and microstructure evolution. Summary of the Invention

[0007] The technical problem to be solved by this invention is that in the existing process of preparing cement modified with nanomaterials, nanomaterials are prone to agglomeration, uneven dispersion, low effective reaction area, and unstable modification effect.

[0008] The technical solution of the present invention is as follows: A pre-dispersion device for cement modified with nanomaterials includes a heating and stirring device, an ultrasonic dispersion control device, a temperature monitoring component, a dispersion container, and a nanomaterial dispersion liquid contained in the dispersion container; the heating and stirring device includes a magnetic heating stirrer and a magnetic stirring rotor; the control device includes an ultrasonic dispersion controller and an ultrasonic dispersion probe electrically connected thereto; the temperature monitoring component includes at least one temperature sensor placed in the nanomaterial dispersion liquid. The dispersion container is placed on the magnetic heating stirrer, and the output stirring shaft of the heating stirrer enters the dispersion container from the bottom center position. The magnetic stirring rotor is installed on the output stirring shaft and is positioned close to the bottom of the inner cavity of the dispersion container. The ultrasonic dispersion probe extends vertically into the nanomaterial dispersion liquid inside the dispersion container from above. The magnetic heating stirrer is equipped with a stirring speed adjustment module and a heating temperature adjustment module. The stirring speed adjustment module is used to control the rotation speed of the magnetic stirring rotor, and the heating temperature adjustment module is used to control the temperature of the nanomaterial dispersion. The ultrasonic dispersion controller is equipped with a power adjustment module, a time adjustment module and a working mode adjustment module, which are used to control the ultrasonic dispersion power, ultrasonic dispersion time and ultrasonic working mode. The ultrasonic working mode includes continuous ultrasonic mode and intermittent ultrasonic mode. The temperature monitoring component is used to monitor the temperature of the nanomaterial dispersion in real time and adjust the ultrasonic dispersion time, ultrasonic power, stirring speed or heating temperature according to temperature changes.

[0009] Preferably, the ultrasonic dispersion time is 10 min to 60 min, the ultrasonic dispersion power is 120 W to 1000 W, the rotation speed of the magnetic stirring rotor is 100 r / min to 1500 r / min, and the temperature of the nanomaterial dispersion is controlled at 20℃ to 60℃.

[0010] Preferably, a distance is maintained between the lower end of the ultrasonic dispersion probe and the magnetic stirring rotor of the dispersion container to avoid contact between the ultrasonic dispersion probe and the magnetic stirring rotor; The ultrasonic dispersion probe is aligned with the axis of the dispersion container.

[0011] Preferably, the nanomaterial includes one or more of the following: nano-silica, nano-alumina, nano-titanium dioxide, nano-calcium carbonate, carbon nanotubes, graphene oxide, and nano-clay; the dispersion medium of the nanomaterial dispersion includes one or more of the following: deionized water, cement mixing water, aqueous solution containing water-reducing agent, aqueous solution containing dispersant, or aqueous solution containing heavy metal ions; when the nanomaterial is nano-silica, the amount of nano-silica is 0.1% to 5% of the cement mass.

[0012] Preferably, the dispersion container is a pre-dispersion container suitable for on-site mixing conditions, including a mobile dispersion bucket, a pre-dispersion tank, a corrosion-resistant dispersion tank, or a closed mixing container with a discharge port; the volume of the dispersion container is determined according to the amount of cement mixing water and the amount of nanomaterials added, preferably 10L~1000L.

[0013] Preferably, the nanomaterial dispersion is used to prepare nanomaterial-modified cement-cured heavy metal materials, wherein the heavy metals include Pb, Cr, Mn, Cd, Zn, Cu, Ni, and As.

[0014] Preferably, the step of using the nanomaterial dispersion 6 to prepare nanomaterial-modified cement is as follows: Step 1, Assembly of the pre-dispersion device; Step 2, preparation of nanomaterials and dispersion media; Step 3, preparation of nanomaterial dispersion; Step 4: Magnetic stirring and temperature control; Step 5, ultrasonic dispersion treatment; Step 6: Mixing the pre-dispersed liquid with cement.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) This invention proposes a pre-dispersion device and dispersion method for nanomaterial-modified cement. Through the synergistic effect of ultrasonic dispersion and magnetic stirring, the nanomaterial agglomerates are destroyed before the nanomaterials are mixed with cement, thereby improving the uniformity of the nanomaterials in the dispersion medium.

[0016] (2) The present invention utilizes an ultrasonic dispersion device to break the agglomeration structure of nanomaterials, and at the same time uses magnetic stirring to form a circulating flow field, so that the nanomaterials continuously enter the ultrasonic action zone, avoiding insufficient local dispersion, unevenness and secondary agglomeration.

[0017] (3) The present invention sets up a temperature control process, which can improve the dispersion efficiency of nanomaterials and avoid excessively high temperature of dispersion liquid caused by long-term ultrasound, thereby reducing the adverse effects on the surface properties of nanomaterials and subsequent cement hydration reaction.

[0018] (4) The present invention pre-disperses the nanomaterials before they enter the cement slurry, which can avoid the problem that the nanomaterials are difficult to disperse after they directly enter the high viscosity cement slurry, and improve the effective specific surface area and reactivity of the nanomaterials in the cement system.

[0019] (5) This invention is applicable to a variety of nanomaterials such as nano-silica, nano-alumina, nano-calcium carbonate, carbon nanotubes, and graphene oxide, and has good versatility and applicability.

[0020] (6) This invention can be used to prepare cement, cement mortar, cement concrete and cement-cured heavy metal materials modified by nanomaterials, and can increase the amount of cement hydration products generated, improve the pore structure and enhance the density and stability of the materials.

[0021] (7) When the present invention is used to modify cement with nano-silica to cure heavy metals such as Pb, Cr, and Mn, the uniformly dispersed nano-silica can promote the formation of CSH gel and refine the pore structure, enhance the adsorption, precipitation, complexation, structural fixation and physical encapsulation of heavy metals in the cement system, thereby reducing the migration and leaching risk of heavy metals.

[0022] (8) The device of the present invention has a simple structure and is easy to operate. It can be directly connected with the existing cement slurry preparation process without complicated modification. It has good laboratory application value and engineering promotion potential. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the pre-dispersion device in an embodiment of the present invention.

[0024] Figure reference numerals: 1-Ultrasonic dispersion controller; 2-Ultrasonic dispersion probe; 3-Dispersion container; 4-Magnetic stirring rotor; 5-Support; 6-Nanomaterial dispersion liquid; 7-Magnetic heating stirrer; 8-Temperature sensor; 9-Clamping device; 10-Height adjustment device. Detailed Implementation

[0025] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0026] Example 1: Pre-dispersion device for nano-silica modified cement.

[0027] Figure 1 This is a schematic diagram of the pre-dispersion device in an embodiment of the present invention. Figure 1 As can be seen, the present invention provides a pre-dispersion device for cement modified with nanomaterials, including a heating and stirring device, an ultrasonic dispersion control device, a temperature monitoring component, a dispersion container 3, and a nanomaterial dispersion liquid 6 contained in the dispersion container 3; the heating and stirring device includes a magnetic heating stirrer 7 and a magnetic stirring rotor 4; the control device includes an ultrasonic dispersion controller 1 and an ultrasonic dispersion probe 2 electrically connected thereto; the temperature monitoring component includes at least one temperature sensor 8, which is placed in the nanomaterial dispersion liquid 6.

[0028] The dispersion container 3 is placed on the magnetic heating stirrer 7. The output stirring shaft of the heating stirrer 7 enters the dispersion container 3 from the bottom center position. The magnetic stirring rotor 4 is installed on the output stirring shaft and is located close to the bottom of the inner cavity of the dispersion container 3. The ultrasonic dispersion probe 2 extends vertically from above into the nanomaterial dispersion liquid 6 inside the dispersion container 3.

[0029] The magnetic heating stirrer 7 is equipped with a stirring speed adjustment module and a heating temperature adjustment module. The stirring speed adjustment module is used to control the rotation speed of the magnetic stirring rotor 4, and the heating temperature adjustment module is used to control the temperature of the nanomaterial dispersion 6.

[0030] The ultrasonic dispersion controller 1 is equipped with a power adjustment module, a time adjustment module and a working mode adjustment module, which are used to control the ultrasonic dispersion power, ultrasonic dispersion time and ultrasonic working mode. The ultrasonic working mode includes continuous ultrasonic mode and intermittent ultrasonic mode.

[0031] The temperature monitoring component is used to monitor the temperature of the nanomaterial dispersion 6 in real time, and adjust the ultrasonic dispersion time, ultrasonic power, stirring speed or heating temperature according to temperature changes.

[0032] In this embodiment, the ultrasonic dispersion time is 10 min to 60 min, the ultrasonic dispersion power is 120 W to 1000 W, the rotation speed of the magnetic stirring rotor 4 is 100 r / min to 1500 r / min, and the temperature of the nanomaterial dispersion 6 is controlled at 20℃ to 60℃.

[0033] In this embodiment, the lower end of the ultrasonic dispersion probe 2 is kept at a distance from the magnetic stirring rotor 4 of the dispersion container 3 to avoid contact between the ultrasonic dispersion probe 2 and the magnetic stirring rotor 4; the ultrasonic dispersion probe 2 is aligned with the axis of the dispersion container 3.

[0034] In this embodiment, the nanomaterial dispersion contains nano-silica and deionized water; specifically, the nanomaterial includes one or more of nano-silica, nano-alumina, nano-titanium dioxide, nano-calcium carbonate, carbon nanotubes, graphene oxide, and nano-clay; the dispersion medium of the nanomaterial dispersion 6 includes one or more of deionized water, cement mixing water, an aqueous solution containing a water-reducing agent, an aqueous solution containing a dispersant, or an aqueous solution containing heavy metal ions; when the nanomaterial is nano-silica, the amount of nano-silica is 0.1% to 5% of the cement mass.

[0035] In this embodiment, the dispersion container 3 is a pre-dispersion container suitable for on-site mixing conditions, including a mobile dispersion bucket, a pre-dispersion tank, a corrosion-resistant dispersion tank, or a closed mixing container with a discharge port; the volume of the dispersion container 3 is determined according to the amount of cement mixing water and the amount of nanomaterials added, preferably 10L~1000L.

[0036] In this embodiment, a bracket 5, a clamping device 9, and a height adjustment device 10 are also included. The clamping device 9 is used to fix the ultrasonic dispersion probe, and the height adjustment device 10 is used to adjust the depth of the ultrasonic dispersion probe inserted into the dispersion liquid.

[0037] Example 2: Preparation method of cement-cured heavy metal material modified with nano-silica.

[0038] The nanomaterial dispersion 6 is used to prepare nanomaterial-modified cement-cured heavy metal materials, wherein the heavy metals include Pb, Cr, Mn, Cd, Zn, Cu, Ni, and As.

[0039] The steps for using the nanomaterial dispersion 6 to prepare nanomaterial-modified cement are as follows: Step 1, Assembly of the pre-dispersion device; Step 2, preparation of nanomaterials and dispersion media; Step 3, preparation of nanomaterial dispersion 6; Step 4: Magnetic stirring and temperature control; Step 5, ultrasonic dispersion treatment; Step 6: Mixing the pre-dispersed liquid with cement.

[0040] In steps 4-6, the nanomaterials are added to the nanomaterial dispersion 6 to form an initial dispersion. The magnetic stirring rotor 4 is then activated to create a stable vortex flow field in the nanomaterial dispersion 6. Subsequently, the ultrasonic dispersion probe 2 is activated to transfer ultrasonic energy into the dispersion. The cavitation bubbles generated by the ultrasonic action create localized high temperatures, high pressures, and microjets during their collapse, which can break down the nano-silica aggregates. The circulating flow field generated by the magnetic stirring promotes the continuous entry of aggregates into the ultrasonic action zone, improving dispersion uniformity.

[0041] After dispersion, the above-treated nanomaterial dispersion 6 is directly added to cement and stirred to prepare nanomaterial-modified cement paste. Since the nanomaterials have been pre-dispersed before entering the cement system, their distribution in the cement paste is more uniform, enabling them to more fully exert their nucleation, filling, and pozzolanic reaction effects.

[0042] In this embodiment, the nanomaterial is nano-silica, and the heavy metals are Pb, Cr, and Mn.

[0043] Uniformly dispersed nano-silica can promote cement hydration, increase CSH gel formation, improve pore structure, and make the cementitious body more dense. For heavy metals such as Pb, Cr, and Mn, cement hydration products can reduce their migration through surface adsorption, ion exchange, precipitation, complexation, structural embedding, and physical encapsulation. The addition of nano-silica further enhances the cement matrix's ability to fix heavy metals, thereby reducing the risk of heavy metal leaching.

Claims

1. A pre-dispersion device for cement modified with nanomaterials, characterized in that, The device includes a heating and stirring device, an ultrasonic dispersion control device, a temperature monitoring component, a dispersion container (3), and a nanomaterial dispersion (6) contained in the dispersion container (3); the heating and stirring device includes a magnetic heating stirrer (7) and a magnetic stirring rotor (4); the control device includes an ultrasonic dispersion controller (1) and an ultrasonic dispersion probe (2) electrically connected thereto; the temperature monitoring component includes at least one temperature sensor (8), which is placed in the nanomaterial dispersion (6); The dispersion container (3) is placed on the magnetic heating stirrer (7). The output stirring shaft of the heating stirrer (7) enters the dispersion container (3) from the bottom center position. The magnetic stirring rotor (4) is installed on the output stirring shaft and is located close to the bottom of the inner cavity of the dispersion container (3). The ultrasonic dispersion probe (2) extends vertically from above into the nanomaterial dispersion liquid (6) in the dispersion container (3). The magnetic heating stirrer (7) is equipped with a stirring speed adjustment module and a heating temperature adjustment module. The stirring speed adjustment module is used to control the rotation speed of the magnetic stirring rotor (4), and the heating temperature adjustment module is used to control the temperature of the nanomaterial dispersion (6). The ultrasonic dispersion controller (1) is equipped with a power adjustment module, a time adjustment module and a working mode adjustment module for controlling the ultrasonic dispersion power, ultrasonic dispersion time and ultrasonic working mode. The ultrasonic working mode includes continuous ultrasonic mode and intermittent ultrasonic mode. The temperature monitoring component is used to monitor the temperature of the nanomaterial dispersion (6) in real time, and adjust the ultrasonic dispersion time, ultrasonic power, stirring speed or heating temperature according to the temperature change.

2. The pre-dispersion device for nanomaterial-modified cement according to claim 1, characterized in that, The ultrasonic dispersion time is 10 min to 60 min, the ultrasonic dispersion power is 120 W to 1000 W, the rotation speed of the magnetic stirring rotor (4) is 100 r / min to 1500 r / min, and the temperature of the nanomaterial dispersion (6) is controlled at 20℃ to 60℃.

3. The pre-dispersion device for nanomaterial-modified cement according to claim 1, characterized in that, The lower end of the ultrasonic dispersion probe (2) is kept at a distance from the magnetic stirring rotor (4) of the dispersion container (3) to avoid contact between the ultrasonic dispersion probe (2) and the magnetic stirring rotor (4). The ultrasonic dispersion probe (2) is aligned with the axis of the dispersion container (3).

4. The pre-dispersion device for nanomaterial-modified cement according to claim 1, characterized in that, The nanomaterials include one or more of nano-silica, nano-alumina, nano-titanium dioxide, nano-calcium carbonate, carbon nanotubes, graphene oxide, and nano-clay; the dispersion medium of the nanomaterial dispersion (6) includes one or more of deionized water, cement mixing water, aqueous solution containing water-reducing agent, aqueous solution containing dispersant, or aqueous solution containing heavy metal ions; when the nanomaterial is nano-silica, the amount of nano-silica is 0.1% to 5% of the cement mass.

5. The pre-dispersion device for nanomaterial-modified cement according to claim 1, characterized in that, The dispersion container (3) is a pre-dispersion container suitable for on-site mixing conditions, including a mobile dispersion barrel, a pre-dispersion tank, a corrosion-resistant dispersion tank, or a closed mixing container with a discharge port; the volume of the dispersion container (3) is determined according to the amount of cement mixing water and the amount of nanomaterials added, preferably 10L~1000L.

6. The pre-dispersion device for nanomaterial-modified cement according to claim 1, characterized in that, The nanomaterial dispersion is used to prepare nanomaterial-modified cement-cured heavy metal materials, wherein the heavy metals include Pb, Cr, Mn, Cd, Zn, Cu, Ni, and As.

7. The pre-dispersion device for nanomaterial-modified cement according to claim 6, characterized in that, The steps for using the nanomaterial dispersion 6 to prepare nanomaterial-modified cement are as follows: Step 1, Assembly of the pre-dispersion device; Step 2, preparation of nanomaterials and dispersion media; Step 3, preparation of nanomaterial dispersion (6); Step 4: Magnetic stirring and temperature control; Step 5, ultrasonic dispersion treatment; Step 6: Mixing the pre-dispersed liquid with cement.

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