A composite modified high-stability functional foamed concrete and its preparation method

Abstract

This invention belongs to the field of building materials technology, specifically relating to a composite modified high-stability functional foamed concrete and its preparation method. This foamed concrete utilizes a binary synergistic stabilizing system composed of hydroxypropyl methylcellulose (HPMC) and amphiphilic nano-titanium dioxide (TiO2), significantly improving foam stability and mechanical strength, and endowing the product with efficient and long-lasting photocatalytic self-cleaning function. Its preparation method includes steps such as the formulation of a functional composite foaming agent, foaming, and mixing with cement-based slurry. This invention solves the problems of poor stability and limited functionality of traditional foamed concrete, exhibiting excellent overall performance.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to an organic-nanoparticle composite modified high-stability functional foamed concrete and its preparation method. Background Technology

[0002] Foamed concrete is a lightweight porous material formed by introducing air bubbles into cement-based slurry. Due to its advantages such as low density, thermal insulation, heat insulation, and sound insulation, it is widely used in building insulation, backfilling, and lightweight structures. However, foamed concrete at low density levels suffers from poor foam stability, such as air bubble aggregation, drainage, and stratification, resulting in uneven pore structure and decreased mechanical properties in the finished product (see patent application CN110117123A, publication date 2019.08.13).

[0003] To improve foam stability, existing technologies often add high-molecular-weight polymers such as hydroxypropyl methylcellulose (HPMC). HPMC can increase the viscosity of the aqueous phase and delay liquid film drainage, but its effect on inhibiting bubble coarsening and gas diffusion is limited (see patent application JP2010254824A). On the other hand, nano-titanium dioxide (TiO2) has been used to endow building materials with photocatalytic functions, but when directly incorporated, it is prone to agglomeration and uneven dispersion, resulting in low photocatalytic efficiency and failing to solve the foam stability problem (see patent application US20160016899A1).

[0004] In recent years, based on the Pickering emulsification principle, some studies have used nanoparticles as foam stabilizers. However, the use of nanoparticles alone requires strict requirements on particle wettability and the process is complicated, making it difficult to apply in practice (see the literature "Langmuir, 2010, 26(12): 97-105").

[0005] Therefore, there is an urgent need in this field for a solution that can organically combine the advantages of organic matter and nanoparticles to synergistically solve the problems of stability, mechanical properties and functionalization of foamed concrete. Summary of the Invention

[0006] The present invention aims to provide a foamed concrete with high foam stability, excellent mechanical properties and photocatalytic function, and its preparation method, thereby solving the problems of poor stability and limited function of traditional foamed concrete.

[0007] To solve the above-mentioned technical problems, the present invention is implemented as follows: This invention provides an organic-nanoparticle composite modified high-stability functional foamed concrete, characterized by comprising a cementitious material, water, and a functional composite foaming agent, wherein the functional composite foaming agent comprises hydroxypropyl methylcellulose, amphiphilic nano-titanium dioxide, and a surfactant, wherein: The amount of the amphiphilic nano-titanium dioxide is 0.5% to 2% of the mass of the cementitious material; The amount of hydroxypropyl methylcellulose added is 0.01% to 0.05% of the mass of the gelling material; The amount of surfactant is 0.5% to 2% of the total mass of the functional composite foaming agent solution.

[0008] Furthermore, the amphiphilic nano-titanium dioxide is anatase-type nano-titanium dioxide modified with a silane coupling agent, with a contact angle of 30° to 80° and an average particle size of 10 to 50 nm.

[0009] Furthermore, the surfactant is dodecyltrimethylammonium bromide.

[0010] Furthermore, the cementing material is ordinary silicate cement.

[0011] Furthermore, the volume ratio of the functional composite foaming agent to the cement paste is 1:1.5 to 1:3.

[0012] The present invention also provides a method for preparing the aforementioned composite modified high-stability functional foamed concrete, comprising the following steps: Step S1: Prepare a functional composite foaming agent solution, including dispersing amphiphilic nano-titanium dioxide in part of the mixing water, adding hydroxypropyl methylcellulose and stirring until completely dissolved, and then adding a surfactant and mixing evenly; Step S2: Prepare highly stable functional foam by using a foaming machine with a functional composite foaming agent solution; Step S3: After dry mixing the cementitious materials, admixtures and water-reducing agents, add the remaining mixing water and stir to form a cement paste; Step S4: Mix the functional foam with the cement paste and stir at low speed until homogeneous to obtain foamed concrete mixture; Step S5: Pour the mixture, allow it to stand and harden, demold it, and then perform standard curing.

[0013] Furthermore, in step S1, the dispersion of the amphiphilic nano-titanium dioxide is achieved by mechanical stirring or ultrasonic treatment, with a stirring speed of 300-600 rpm and an ultrasonic treatment time of 10-30 minutes.

[0014] Furthermore, in step S2, the foaming machine is a mechanical foaming device, and the half-life of the functional foam obtained after foaming is not less than 180 minutes.

[0015] Furthermore, in step S4, the low-speed stirring speed is 50-100 rpm, and the stirring time is 2-5 minutes.

[0016] Furthermore, in step S5, the standard curing conditions are: temperature 20±2℃, humidity greater than 95%.

[0017] Compared with the prior art, the advantages of this invention are as follows: (1) Excellent foam stability: HPMC thickening and amphiphilic nano-TiO2 interface “particle armor” work together to achieve a foam half-life of more than 180 minutes and a uniform and fine pore structure (average pore size ≤250μm).

[0018] (2) Excellent mechanical properties: The compressive strength is increased by more than 20% under the same density, and the compressive strength after 28 days reaches 6.0 to 6.5 MPa.

[0019] (3) High efficiency and long-lasting photocatalytic function: The efficiency of photocatalytic degradation of pollutants is 30% to 50% higher than that of traditional mixing method, and the nano TiO2 is firmly fixed on the pore wall and is not easy to be lost.

[0020] (4) Good overall benefits: While ensuring performance, density or cement usage can be reduced, resulting in significant cost benefits. Attached Figure Description

[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 The flowchart illustrates the preparation method of organic-nanoparticle composite modified high-stability functional foamed concrete provided by this invention. Detailed Implementation

[0022] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] The terms "first," "second," etc., used in the specification and claims of this invention are used to distinguish similar objects and not to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention can be implemented in orders other than those illustrated or described herein, and the objects distinguished by "first," "second," etc., are generally of the same class and the number of objects is not limited; for example, a first object can be one or more. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0024] This invention provides an organic-nanoparticle composite modified high-stability functional foamed concrete, comprising cementitious materials, water, and a functional composite foaming agent. The functional composite foaming agent contains hydroxypropyl methylcellulose, amphiphilic nano-titanium dioxide, and a surfactant, wherein: The amount of the amphiphilic nano-titanium dioxide is 0.5% to 2% of the mass of the cementitious material; The amount of hydroxypropyl methylcellulose added is 0.01% to 0.05% of the mass of the gelling material; The amount of surfactant is 0.5% to 2% of the total mass of the functional composite foaming agent solution.

[0025] The amphiphilic nano-titanium dioxide is anatase-type nano-titanium dioxide modified with a silane coupling agent, with a contact angle of 30° to 80° and an average particle size of 10 to 50 nm. The silane coupling agent can be KH-550 silane coupling agent.

[0026] The surfactant is dodecyltrimethylammonium bromide.

[0027] The cementing material is ordinary Portland cement.

[0028] The volume ratio of the functional composite foaming agent to the cement paste is 1:1.5 to 1:3.

[0029] Please see Figure 1 As shown, the present invention also provides a method for preparing the aforementioned organic-nanoparticle composite modified high-stability functional foamed concrete, comprising the following steps: Step S1: Prepare a functional composite foaming agent solution, including dispersing amphiphilic nano-titanium dioxide in part of the mixing water, adding hydroxypropyl methylcellulose and stirring until completely dissolved, and then adding a surfactant and mixing evenly; Step S2: Prepare highly stable functional foam by using a foaming machine with a functional composite foaming agent solution; Step S3: After dry mixing the cementitious materials, admixtures and water-reducing agents, add the remaining mixing water and stir to form a cement paste; Step S4: Mix the functional foam with the cement paste and stir at low speed until homogeneous to obtain foamed concrete mixture; Step S5: Pour the mixture, allow it to stand and harden, demold it, and then perform standard curing.

[0030] In step S1, the dispersion of the amphiphilic nano-titanium dioxide is achieved by mechanical stirring or ultrasonic treatment, with a stirring speed of 300-600 rpm and an ultrasonic treatment time of 10-30 minutes.

[0031] In step S2, the foaming machine is a mechanical foaming device, and the half-life of the functional foam obtained after foaming is not less than 180 minutes.

[0032] In step S4, the low-speed stirring speed is 50-100 rpm, and the stirring time is 2-5 minutes.

[0033] In step S5, the standard curing conditions are: temperature 20±2℃ and humidity greater than 95%.

[0034] The preparation method of organic-nanoparticle composite modified high-stability functional foamed concrete provided by the present invention will be described in detail below with specific embodiments and comparative examples.

[0035] Example 1: Validation of Synergistic Effect This embodiment aims to demonstrate the necessity of the synergistic effect between HPMC and amphiphilic nano-TiO2.

[0036] Raw materials and proportions (based on 100 parts by weight of cement): Cementitious material: Ordinary Portland cement (PO 42.5), 100 parts.

[0037] Water: 35 parts (water-cement ratio 0.35).

[0038] Foaming agent: Animal protein foaming agent, 0.5%.

[0039] Comparative Example 1: Only 0.03% HPMC (by mass of cement) was added.

[0040] Comparative Example 2: Only 1.5% of amphiphilic nano-TiO2 (average particle size 20nm, anatase type) was added.

[0041] Invention Group: Simultaneous addition of 0.03% HPMC and 1.5% amphiphilic nano-TiO2.

[0042] Surfactant: DTAB, added at 1% of the total mass of the functional composite foaming agent solution.

[0043] The volume ratio of functional foam to cement paste is 1:2.

[0044] Preparation method: Step S1: Disperse the amphiphilic nano-TiO2 in a portion of the mixed water by ultrasonication for 10 minutes, add HPMC and stir to dissolve, then add DTAB and mix.

[0045] Step S2: Prepare foam using a mechanical foaming machine.

[0046] Step S3: Mix cement and remaining water to form a slurry.

[0047] Step S4: Mix the foam and slurry at low speed (80 rpm, 3 minutes).

[0048] Step S5: After pouring and hardening, cure for 28 days at 20±2℃ and humidity>95%.

[0049] Performance Tests and Results: Foam half-life: The half-life of the invention group's foam exceeded 180 minutes, which is much longer than that of Comparative Example 1 (about 45 minutes) and Comparative Example 2 (about 90 minutes), demonstrating that the synergistically stable system greatly extends the foam life.

[0050] Average pore size: The pore structure formed by the invention group is the most uniform and fine, with an average pore size of about 210 micrometers, which is significantly better than Comparative Example 1 (about 350 micrometers, with uneven pore size) and Comparative Example 2 (about 240 micrometers).

[0051] Compressive strength: The compressive strength of the invention group reached 6.3 MPa after 28 days, which is a significant improvement compared with Comparative Example 1 (approximately 4.8 MPa) and Comparative Example 2 (approximately 5.2 MPa), clearly demonstrating that there is a synergistic enhancement effect between HPMC and amphiphilic nano-TiO2.

[0052] Example 2: Optimization of nano-TiO2 doping In this embodiment, the HPMC doping amount was fixed at 0.03% to explore the optimal doping amount of amphiphilic nano-TiO2. The preparation method was the same as in Example 1, and the target dry density was controlled at (600±20) kg / m³.

[0053] Test results: When the amphiphilic nano-TiO2 doping content is 0.5%, the foam half-life is about 120 minutes and the 28-day compressive strength is 5.5 MPa.

[0054] When the doping concentration was increased to 1.0%, the half-life was extended to approximately 160 minutes, and the strength increased to 5.9 MPa.

[0055] When the dosage reaches 1.5%, all performance indicators reach their peak values, the foam half-life exceeds 180 minutes, and the compressive strength is 6.3 MPa.

[0056] Increasing the content further to 2.0% does not significantly improve performance. From an economic perspective, 1.5% is the optimal doping amount for amphiphilic nano-TiO2.

[0057] Example 3: Performance comparison with commercial reinforcing agents The group of this invention (0.03% HPMC + 1.5% amphiphilic nano-TiO2) was compared with a control group doped with 1.5% commercial nano-SiO2 (as a reinforcing agent). Tests were conducted at the same density (600 kg / m³).

[0058] Test results: Compressive strength: The 28-day compressive strength of the present invention group is 6.3 MPa, which is slightly higher than the 6.0 MPa of the nano SiO2 group.

[0059] Workability: The cement paste of the present invention has better fluidity, better workability of the mixture, and is easier to construct on site.

[0060] Functionality: The present invention group has a significant ability to photocatalytically degrade pollutants, while the nano SiO2 group does not have this function.

[0061] This embodiment demonstrates that the present invention has a simple process, low cost, and is applicable to fields such as building insulation, lightweight structures, and self-cleaning wall surfaces, and is easy to mass-produce.

[0062] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0063] Furthermore, it should be noted that the scope of the methods and systems in the embodiments of the present invention is not limited to performing functions in the order shown or discussed, but may also include performing functions substantially simultaneously or in the reverse order, depending on the functions involved. For example, the described methods may be performed in a different order than described, and various steps may be added, omitted, or combined. In addition, features described with reference to certain examples may be combined in other examples.

[0064] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. A composite modified high-stability functional foamed concrete, characterized in that, The mixture includes cementitious materials, water, and a functional composite foaming agent, wherein the functional composite foaming agent comprises hydroxypropyl methylcellulose, amphiphilic nano-titanium dioxide, and a surfactant, wherein: The amount of the amphiphilic nano-titanium dioxide is 0.5% to 2% of the mass of the cementitious material; The amount of hydroxypropyl methylcellulose added is 0.01% to 0.05% of the mass of the gelling material; The amount of surfactant is 0.5% to 2% of the total mass of the functional composite foaming agent solution.

2. The foamed concrete of claim 1, wherein, The amphiphilic nano-titanium dioxide is anatase-type nano-titanium dioxide modified with a silane coupling agent, with a contact angle of 30° to 80° and an average particle size of 10 to 50 nm.

3. The foamed concrete of claim 1, wherein, The surfactant is dodecyltrimethylammonium bromide.

4. The foamed concrete of claim 1, wherein, The cementing material is ordinary Portland cement.

5. The foamed concrete of claim 1, wherein, The volume ratio of the functional composite foaming agent to the cement paste is 1:1.5 to 1:

3.

6. A method for preparing the composite modified high-stable functional foamed concrete according to any one of claims 1 to 5, characterized in that, Includes the following steps: Step S1: Prepare a functional composite foaming agent solution, including dispersing amphiphilic nano-titanium dioxide in part of the mixing water, adding hydroxypropyl methylcellulose and stirring until completely dissolved, and then adding a surfactant and mixing evenly; Step S2: Prepare highly stable functional foam by using a foaming machine with a functional composite foaming agent solution; Step S3: After dry mixing the cementitious materials, admixtures and water-reducing agents, add the remaining mixing water and stir to form a cement paste; Step S4: Mix the functional foam with the cement paste and stir at low speed until homogeneous to obtain foamed concrete mixture; Step S5: Pour the mixture, allow it to stand and harden, demold it, and then perform standard curing.

7. The method as described in claim 6, characterized in that, In step S1, the dispersion of the amphiphilic nano-titanium dioxide is achieved by mechanical stirring or ultrasonic treatment, with a stirring speed of 300-600 rpm and an ultrasonic treatment time of 10-30 minutes.

8. The method as described in claim 6, characterized in that, In step S2, the foaming machine is a mechanical foaming device, and the half-life of the functional foam obtained after foaming is not less than 180 minutes.

9. The method as described in claim 6, characterized in that, In step S4, the low-speed stirring speed is 50-100 rpm, and the stirring time is 2-5 minutes.

10. The method as described in claim 6, characterized in that, In step S5, the standard curing conditions are: temperature 20±2℃ and humidity greater than 95%.

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