CN115959866A - Self-cleaning concrete adopting aluminum-based composite hydrolysis byproducts and preparation method thereof - Google Patents

Abstract

The invention discloses a self-cleaning concrete using hydrolysis by-products of aluminum-based composite materials and a preparation method thereof. The hydrolysis by-products of aluminum-based composite materials are introduced into self-cleaning concrete to provide the preparation method. Raw materials include the following components by weight: cement 240-330kg, mineral powder 40-130kg, fly ash 40-70kg, machine-made sand 710-770kg, crushed stone 1060-1120kg, TiO2/γ-Al2O3 composite photocatalyst 15-20kg, 3.6~5.1kg of water reducer, 140~160kg of water. The invention recovers the hydrolysis by-products of the aluminum-based composite material to prepare TiO2/γ-Al2O3 photocatalyst, which is used to prepare self-cleaning concrete. The recovered γ-Al2O3 not only improves the ability of pure TiO2 to degrade pollutants in the air, but also enhances the hydrophobic performance, and there are almost no traces of water droplets on the surface of the concrete. When dust or photocatalytic by-products are formed on the surface, it can be self-cleaned by raindrops to ensure a clean appearance of the concrete, and the photocatalyst can be reused. The method for preparing self-cleaning concrete not only maximizes the utilization of aluminum-based composite materials, reduces costs, but also endows concrete with excellent self-cleaning ability, killing two birds with one stone, and has important practical application value.

Description

A self-cleaning concrete using hydrolysis by-products of aluminum-based composite materials and its preparation method

technical field

The invention relates to the field of building materials, in particular to a self-cleaning concrete using hydrolysis by-products of aluminum-based composite materials and a preparation method thereof.

Background technique

In recent years, industrialization has developed rapidly, global urbanization has led to a surge in the number of cars, and the continuous burning of fossil fuels has brought about increasingly prominent air pollution problems. Vehicle exhaust emission is the main factor of urban air pollution, and a large amount of nitrogen oxides seriously threatens human health. How to achieve sustainable environmental development has become the main issue of social development, and exhaust emissions have become a key issue in reducing air pollution. Nowadays, although the requirements for emission control have been strengthened and many energy-saving and emission-reduction devices have been added, the air pollution The problem still cannot be effectively solved. Common buildings do not have the ability to degrade pollutants and self-cleaning. In recent years, nano-titanium dioxide has the characteristics of low toxicity and strong redox, and has been widely used in the preparation process of photocatalytic coatings. However, the paint often falls off and decomposes by itself, which greatly weakens the photocatalytic performance, and the efficiency of pure Tio ₂ as a photocatalyst is low. How to improve the photocatalytic performance of TiO ₂ and provide a material that can be closely combined with concrete to degrade air pollutants while keeping buildings clean is an urgent problem to be solved when applied to self-cleaning concrete.

The reaction of aluminum matrix composite materials and water to produce hydrogen has attracted much attention in the field of hydrogen energy. It is a non-toxic and pollution-free hydrogen production method, which has the characteristics of mobile, online and real-time hydrogen production. Aluminum is easy to form a dense oxide film at room temperature, and it is often combined with low melting point metals (In, Sn, Ga, etc.) to hinder the formation of an oxide film on the aluminum surface. The reaction products are harmless Al(OH) ₃ and AlOOH. How to recover and utilize the by-products is an effective means to reduce the cost of aluminum water, and it is also a key issue affecting its application in the field of vehicle fuel cells.

Contents of the invention

Based on the above deficiencies in the prior art, the technical problem to be solved by the present invention is to provide a self-cleaning concrete using hydrolysis by-products of aluminum matrix composite materials and its preparation method, to solve the problem of the application of hydrolysis by-products of aluminum matrix composite materials and the problem of pure _TiO2 light The problem of poor catalytic performance.

In order to solve the above technical problems, the present invention provides a self-cleaning concrete using hydrolysis by-products of aluminum-based composite materials. ～770kg machine-made sand, 1000～1100kg gravel, 3.5～5.0kg water reducing agent, 130～150kg water and 0～15kg TiO ₂ /Al ₂ O ₃ composite photocatalyst.

As a preference for the above-mentioned technical solution, the self-cleaning concrete using aluminum-based composite hydrolysis by-products provided by the present invention further includes part or all of the following technical features:

As an improvement of the above technical solution, the nano-titanium dioxide of the TiO ₂ /Al ₂ O ₃ composite photocatalyst is an anatase type.

As an improvement of the above technical solution, the cement is P·O42.5 Portland cement or P·II42.5 Portland cement.

As an improvement of the above technical solution, the slag powder is S95 grade granulated blast furnace slag powder that meets the standard of GB/T18046-2017 "Granulated Blast Furnace Slag Powder Used in Cement, Mortar and Concrete".

As an improvement of the above technical solution, the fineness modulus of the machine-made sand is 2.3-3.0, the MB value is ≤1.4, and the stone powder content is 7-10%.

As an improvement of the above technical solution, the gravel is continuously graded in the range of 5-25mm, the mud content is less than 0.5%, and the mass content of the needle-like particles is ≤8%.

As an improvement of the above-mentioned technical scheme, the fly ash is Class II fly ash,

As an improvement of the above technical solution, the TiO ₂ /Al ₂ O ₃ composite photocatalyst is prepared by the following method:

1) react the aluminum-based composite material with deionized water, and record it as solution A;

2) Pour out the supernatant in solution A, and the remaining small part of water and the product are dispersed evenly by ultrasonic, which is recorded as solution B;

3) Add water to solution B and repeatedly suction and filter. After the water is drained, rinse most of the metal compounds (InSn ₄ , Al) at the bottom with water, then add the product into water, stir, ultrasonically disperse, and place in a centrifuge. After the centrifugation is completed, the supernatant is poured out, and a small amount of metal compounds (InSn ₄ , Al) remaining at the bottom of the solid are washed and removed, and placed in a blast drying oven. After the drying is completed, the solid C is fully ground;

4) Prepare an absolute ethanol solution of tetrabutyl titanate, stir it well, and record it as solution A;

5) Solid C is evenly dispersed in deionized water containing absolute ethanol and acetic acid, the milky white solution is recorded as solution B, and the solution of deionized water containing absolute ethanol and acetic acid is designated as solution D;

6) In the state of high-speed stirring, slowly add solution A to solution B dropwise. After the titration is completed, continue to stir for 30-60 minutes, dry, grind into powder, put it into a muffle furnace for calcination, and cool to room temperature with the furnace. Rinse with ethanol, dry and fully grind into powder to obtain TiO ₂ /Al ₂ O ₃ composite photocatalyst, wherein the nano titanium dioxide produced by calcining is anatase type.

As an improvement of the above-mentioned technical solution, according to the above-mentioned steps, the system of the aluminum-based composite material in 1) is: Al-Ga-In-Sn, Al-Ga-In-Sn-NaCl, etc. The deionized water temperature is 50°C to 70°C. The reaction time is 12-24h;

According to the above steps, the rotational speed of the centrifuge in 3) is 8000-10000 rpm, and the time is 1-2 minutes.

According to the above steps, the volume ratio of tetrabutyl titanate to absolute ethanol in 4) is: 1:3-5;

According to the above steps, 5) in absolute ethanol, deionized water, acetic acid and volume ratio: 1:(0.1～0.30):(0.04～0.06);

According to the above steps, 6) the temperature of the muffle furnace is 300°C-400°C, the heating rate is 2-2.5°C/min, and the heat preservation is 2-3h;

According to the above steps, the ultrasonic frequency used in 1)~6) is 450-600W, the temperature setting of the blast drying oven is 60~80°C, the time is 8~12h, and the mass ratio of solution D to solid C is 1:( 1~3).

A method for preparing self-cleaning concrete using hydrolysis by-products of aluminum-based composite materials as described in any one of the above, characterized in that it comprises the following steps:

1) First add machine-made sand, cement, mineral powder, fly ash, part of water, and water reducer to the concrete mixer for pre-mixing, then add and mix evenly, then add stones and remaining water and continue stirring. The total mixing time is not less than 200s ;

2) After discharging, pouring, vibrating, forming, and curing after removing the formwork, the self-cleaning concrete using the hydrolysis by-product of the aluminum-based composite material can be obtained.

Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

1. The present invention combines the hydrolysis by-products of the aluminum-based composite material with the preparation method of titanium dioxide, and obtains TiO ₂ /γ-Al ₂ O ₃ by a one-step calcination method. The γ-Al ₂ O ₃ formed by calcination is amorphous and has many photoelectron defects, which are conducive to capturing electrons generated by gC ₃ N ₄ and improving the separation efficiency of electrons and holes. When γ-Al ₂ O ₃ is used as a photocatalyst carrier to support TiO ₂ , it not only improves the ability of pure TiO ₂ to degrade pollutants in the air, but also enhances the hydrophobic performance, and there is almost no sagging of water droplets on the surface of concrete. The UV-diffuse reflectance absorption spectrum shows that γ-Al ₂ O ₃ has photoresponse ability under ultraviolet light, and the absorption edge of TiO ₂ /γ-Al ₂ O ₃ has a red shift phenomenon, that is, the photoresponse ability of the composite material is enhanced, and the purity is improved. Photocatalytic properties of _TiO2 . When the composite material is used in self-cleaning concrete, since the TiO ₂ /γ-Al ₂ O ₃ composite photocatalyst has hydrophobic properties, it does not need to be mixed with other hydrophobic materials, and the ratio can also be considered, and the concrete can also have excellent photocatalytic properties. Catalytic and hydrophobic properties. Under the irradiation of sunlight, the concrete excites the catalyst to generate electron-holes, reacts to generate active particles, and oxidizes and reduces the pollutants adsorbed on the surface to achieve the purpose of degradation. In addition, TiO ₂ /γ-Al ₂ O ₃ is directly mixed into the concrete, which is closely combined with the material and is not easy to fall off. It not only reduces the difficulty of operation, but also helps to fill the pores, strengthen the stability of the structure and improve the durability.

2. The present invention introduces the product of the reaction between the aluminum-based composite material and water into the field of building materials, uses the product as a carrier material to improve the photocatalytic performance of pure TiO ₂ , and reuses the product as a by-product of hydrolysis of the aluminum-based composite material for hydrogen production. Reuse provides a way of thinking to promote the formation of a complete industrial chain of aluminum matrix composites.

3. The self-cleaning concrete prepared by the present invention has low raw material cost and simple preparation method.

The above description is only an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention, it can be implemented according to the contents of the description, and in order to make the above and other purposes, features and advantages of the present invention more obvious and understandable , below in conjunction with the preferred embodiment, the detailed description is as follows.

Detailed ways

Specific embodiments of the present invention are described in detail below, which, as a part of the description, illustrate the principle of the present invention through examples, and other aspects, features and advantages of the present invention will become clear through the detailed description.

In the following examples, each raw material is as follows:

The cement is Huaxin P·O42.5 ordinary Portland cement; the fly ash is Class II fly ash of Zhenjiang Jianbi Power Plant, with a loss on ignition of 3.2%; the mineral powder is S95 blast furnace slag produced by Jiangnan Grinding Co., Ltd.; machine-made sand Pebble crushing, 1-4.75mm continuous gradation, fineness modulus 2.7, stone powder content 8%, MB value 1.0; crushed stone is basalt gravel with 5-25mm continuous gradation, mud content less than 0.5%, needle flakes The mass content of granular particles is 7%, and the crushing value is 6%. The water reducer is a polycarboxylate water reducer made by China Construction Commercial Concrete Co., Ltd., and the water reduction rate is 25%. The water is deionized water.

In the following examples and comparative examples, the TiO ₂ /γ-Al ₂ O ₃ composite photocatalyst was prepared according to the following steps:

1) React the aluminum-based composite material (Al-Ga-In-Sn-NaCl) with 70°C deionized water for 12 hours, and record it as solution A;

2) Pour out the supernatant in solution A, and the remaining small part of water and the product 600W ultrasonically disperse evenly, and record it as solution B;

3) Add water to solution B and repeatedly suction and filter. After the water is drained, rinse most of the metal compounds (InSn ₄ , Al) at the bottom with water, then add the product to water, stir, 600W ultrasonic dispersion, and place it in a centrifuge at 10000rpm, time 1min. After the centrifugation is completed, pour out the supernatant, rinse and remove a small amount of metal compounds (InSn ₄ , Al) remaining at the bottom of the solid, place it in a blast drying oven, and keep it warm at 80°C for 12 hours. After drying, fully grind to obtain solid C;

4) Pour tetrabutyl titanate into a container and keep stirring, add absolute ethanol during the stirring process, and stir at room temperature for 60 minutes to obtain solution D, wherein the volume ratio of butyl titanate to absolute ethanol is 1: 5;

5) Add deionized water to the container, continue to add absolute ethanol and acetic acid under ultrasonic stirring, and record it as solution E, and then add solid C in step 3) to obtain a uniformly dispersed milky white solution F, in which absolute ethanol, The volume ratio of deionized water to acetic acid is 1:0.3:0.05, and the mass ratio of solution E to solid C is 1:3;

6) Add solution D dropwise to milky white solution E, stir the solution at a high speed during the dropwise addition, continue to stir for 60 minutes after the dropwise addition, and dry it with a blower at a temperature of 80°C for 12 hours, and grind it into powder after completion , placed in a muffle furnace at 2°C/min to 300°C for calcination, the holding time is 4h, cooled to room temperature with the furnace, washed the surface with ethanol, dried, and fully ground into powder to obtain TiO ₂ /γ-Al ₂ O _3. Composite photocatalyst, the nano-titanium dioxide is anatase type.

Example 1

A self-cleaning concrete using hydrolysis by-products of aluminum-based composite materials. Each cubic concrete contains the following components: 240kg of cement, 40kg of mineral powder, 40kg of fly ash, 781.9kg of machine-made sand, 1172.9kg of crushed stone, TiO ₂ /γ-Al ₂ O ₃ composite photocatalyst 15kg, water reducer 3.5kg, water 106.7kg.

A method for preparing self-cleaning concrete using hydrolysis by-products of aluminum-based composite materials comprises the following steps:

1) Add machine-made sand, cement, mineral powder, fly ash, half of the water, and water reducing agent into the concrete mixer for pre-mixing for 1 minute;

2) Add TiO ₂ /γ-Al ₂ O ₃ composite photocatalyst evenly and stir for 1 min;

3) Then add stones and remaining water to continue stirring, the total stirring time is not less than 200s;

4) Evenly brush the release agent on the mold, pour the self-cleaning concrete mixture using the hydrolysis by-product of the aluminum matrix composite material into the mold and vibrate;

5) Removing the formwork after curing and then continuing the curing to obtain self-cleaning concrete using hydrolysis by-products of aluminum-based composite materials.

Example 2

The only difference from Example 1 is:

A self-cleaning concrete using hydrolysis by-products of aluminum-based composite materials. Each cubic concrete contains the following components: 320kg of cement, 120kg of mineral powder, 70kg of fly ash, 679.6kg of machine-made sand, 1019kg of crushed stone, and TiO ₂ /γ-Al ₂ O ₃ composite photocatalyst 25kg, water reducing agent 3.99kg, water 170kg.

Example 3

The only difference from Example 1 is:

A self-cleaning concrete using hydrolysis by-products of aluminum-based composite materials. Each cubic concrete contains the following components: 300kg of cement, 80kg of mineral powder, 50kg of fly ash, 720.9kg of machine-made sand, 1081.3kg of crushed stone, TiO ₂ /γ-Al ₂ O ₃ composite photocatalyst 20kg, water reducer 4.50kg, water 143.3kg.

Comparative example 1

The only difference from Example 1 is:

A self-cleaning concrete soil using hydrolysis by-products of aluminum-based composite materials. Each cubic concrete contains the following components: 320kg of cement, 120kg of mineral powder, 70kg of fly ash, 681.6kg of machine-made sand, 1022kg of crushed stone, pure TiO ₂ photocatalyst 25kg, water reducer 3.99kg, water 170kg.

Comparative example 2

The only difference from Example 1 is:

A self-cleaning concrete using hydrolysis by-products of aluminum-based composite materials. Each cubic concrete contains the following components: 320kg of cement, 120kg of mineral powder, 70kg of fly ash, 681.6kg of machine-made sand, 1022kg of crushed stone, water-reducing Agent 3.99kg, water 170kg

Comparative Example 1 and Comparative Example 2 are used as comparisons with Example 2 for the purpose of testing the influence of the presence or absence of carrier γ-Al ₂ O ₃ on the photocatalytic and hydrophobic properties.

Performance test method:

1. After the curing is completed, observe the color and appearance of the self-cleaning concrete using the hydrolysis by-products of the aluminum matrix composite material, and carefully observe the cracks and holes;

2. Under simulated sunlight conditions, continuously pass _NOx with a concentration of 80ppm in a sealed plexiglass photocatalytic reaction box to measure its photocatalytic rate;

3. Sprinkle dust on the surface and sides of the concrete to simulate raining conditions for more than 60 seconds, and observe the phenomenon of water droplets flowing on the concrete surface.

Table 1 shows the NO _x of self-cleaning concrete using hydrolysis by-products of aluminum-based composite materials obtained in various examples and comparative examples.

Table 1 Examples 1-3, Comparative Examples 1-2 Self-cleaning concrete performance test results

From the performance test results in the above table, it can be seen that the self _- cleaning concrete prepared by the present invention adopts the _hydrolysis by-products of the aluminum _- based composite material. The catalytic performance has been greatly improved, with excellent photocatalytic activity, and the NOx degradation rate is as high as 79%, which can greatly improve the environmental pollution of automobile exhaust; while comparing Example 2, Comparative Example 1 and Comparative Example 2, using γ-Al ₂ O ₃ is used as the carrier. It is not difficult to find that the hydrophobic performance of concrete is enhanced while the photocatalytic performance is improved. When there is dust on the surface, dust and other pollutants can be taken away by rainwater, and there is a small amount or no trace; at the same time The generation of cracks and holes on the concrete surface is improved, the concrete does not need to be modified, has a beautiful decorative feeling, and has practical application value.

Each raw material enumerated in the present invention, and the upper and lower limits of each raw material of the present invention, the interval value, and the upper and lower limits of process parameters (such as temperature, time, etc.), the interval value can realize the present invention, do not enumerate one by one here Example.

The above description is only a preferred embodiment of the present invention, and of course the scope of rights of the present invention cannot be limited by this. It should be pointed out that for those of ordinary skill in the art, they can also Several improvements and changes are made, and these improvements and changes are also regarded as the protection scope of the present invention.

Claims (10)

1. A self-cleaning concrete employing aluminum matrix composite hydrolysis byproducts, said self-cleaning concrete comprising: 230-320 kg of cement, 30-120 kg of mineral powder, 30-70 kg of fly ash, 700-770 kg of machine-made sand, 1000-1100 kg of broken stone, 3.5-5.0 kg of water reducing agent, 130-150 kg of water and 0-15 kg of TiO ₂ /Al ₂ O ₃ A composite photocatalyst is provided.

2. The self-cleaning concrete using aluminum matrix composite hydrolysis by-products of claim 1, wherein: the TiO is ₂ /Al ₂ O ₃ The nano titanium dioxide of the composite photocatalyst is anatase.

3. The self-cleaning concrete using aluminum matrix composite hydrolysis by-products of claim 1, wherein: the cement is P.O 42.5 portland cement or P.II 42.5 portland cement.

4. The self-cleaning concrete using aluminum matrix composite hydrolysis by-products of claim 1, wherein: the mineral powder is S95-level granulated blast furnace slag powder which meets the standard of GB/T18046-2017 granulated blast furnace slag powder for cement, mortar and concrete.

5. The self-cleaning concrete using aluminum matrix composite hydrolysis by-products of claim 1, wherein: the fineness modulus of the machine-made sand is 2.3-3.0, the MB value is less than or equal to 1.4, and the content of the stone powder is 7-10%.

6. The self-cleaning concrete using aluminum matrix composite hydrolysis by-products of claim 1, wherein: the broken stone is in 5-25 mm continuous gradation, the mud content is less than 0.5%, and the mass content of the needle-shaped particles is less than or equal to 8%.

7. The self-cleaning concrete using aluminum matrix composite hydrolysis by-products of claim 1, wherein: the fly ash is II-grade fly ash,

8. the self-cleaning concrete using aluminum matrix composite hydrolysis by-products of claim 1, wherein: the TiO is ₂ /Al ₂ O ₃ The composite photocatalyst is prepared by the following method:

1) Reacting the aluminum-based composite material with deionized water, and marking as a solution A;

2) Pouring out the supernatant in the solution A, and uniformly dispersing the rest part of water and the product by ultrasonic waves to obtain a solution B;

3) Adding clear water into the solution B for repeated suction filtration, draining water, and washing most metal compounds (InSn) at the bottom with clear water ₄ Al), adding the product into water, stirring, ultrasonically dispersing, and placing in a centrifuge. After the centrifugation is completed, the supernatant is poured out, and a small amount of metal compound (InSn) is remained at the bottom of the solid ₄ Al), washing and removing, placing in a forced air drying oven, and fully grinding to obtain solid C after drying;

4) Preparing an absolute ethyl alcohol solution of tetrabutyl titanate, fully stirring, and marking as a solution A;

5) Uniformly dispersing the solid C in deionized water containing absolute ethyl alcohol and acetic acid, wherein a milky solution is marked as a solution B, and a solution of the deionized water containing the absolute ethyl alcohol and the acetic acid is marked as a solution D;

6) Slowly dropwise adding the solution A into the solution B under high-speed stirring, continuously stirring for 30-60min after titration, drying, grinding into powder, calcining in a muffle furnace, cooling to room temperature, washing with ethanol, drying, and sufficiently grinding into powder to obtain TiO ₂ /Al ₂ O ₃ The nanometer titanium dioxide prepared by calcination is anatase type.

9. The self-cleaning concrete using aluminum matrix composite hydrolysis by-products and the method of preparing the same as claimed in claim 8, wherein:

according to the steps, the system of the aluminum-based composite material in 1) is as follows: al-Ga-In-Sn, al-Ga-In-Sn-NaCl, etc. The temperature of the deionized water is 50-70 ℃. The reaction time is 12-24h;

according to the steps, the rotating speed of the centrifugal machine in the step 3) is 8000-10000 rpm, and the time is 1-2 min.

According to the steps, the volume ratio of tetrabutyl titanate to absolute ethyl alcohol in the step 4) is as follows: 1:3 to 5;

according to the steps, in 5), absolute ethyl alcohol, deionized water, acetic acid and the volume ratio are as follows: 1, (0.1-0.30) and (0.04-0.06);

according to the steps, 6), the temperature of the muffle furnace is 300-400 ℃, the heating rate is 2-2.5 ℃/min, and the heat preservation time is 2-3 h;

according to the steps, the ultrasonic frequency used in 1) to 6) is 450-600W, the temperature of the air-blast drying oven is 60-80 ℃, the time is 8-12 h, and the mass ratio of the solution D to the solid C is 1: (1-3).

10. A method for preparing self-cleaning concrete using hydrolysis by-products of aluminum matrix composites as claimed in claim 1, comprising the steps of:

1) Firstly, adding the machine-made sand, the cement, the mineral powder, the fly ash, part of water and the water reducing agent into a concrete mixer for even pre-mixing, then adding the mixture for even mixing, then adding the stones and the residual water for continuous mixing, wherein the total mixing time is not less than 200s;

2) Pouring, vibrating, forming and curing after demoulding are carried out after discharging, and the self-cleaning concrete adopting the hydrolysis by-product of the aluminum-based composite material is obtained.