A foam alkali-activated cementitious material and a method of making the same

Abstract

The application provides a foamed alkali-activated cementitious material, which is composed of an intermediate layer and surface layers covering the upper and lower surfaces of the intermediate layer, and the intermediate layer and the surface layers comprise the following raw materials: 30-50 parts by mass of blast furnace slag, 12-18 parts by mass of low-calcium fly ash, 9-15 parts by mass of alkaline magnesium slag, 10-15 parts by mass of alkali activator, 6-8 parts by mass of foaming agent and 3-5 parts by mass of foam stabilizer; the surface layer further comprises 1.5-5 parts by mass of functional catalyst, and the functional catalyst is gel-like micro-nano TiO2 particles. The application utilizes fly ash, magnesium slag and slag and other types of solid waste to prepare building materials with the ability to degrade formaldehyde. Compared with traditional porous foamed materials, the foamed alkali-activated cementitious material prepared by using aluminum powder as a foaming agent has the advantage of utilizing industrial by-products, and the excess aluminum powder not only produces a dense and uniform pore structure, but also is conducive to the adsorption of formaldehyde gas and the improvement of mechanical strength.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of functional utilization of solid waste, and particularly relates to a foamed alkali-activated gel material and a preparation method thereof. BACKGROUND

[0002] With the pursuit of high-quality life and good living conditions, more than 80% of residents' time is spent indoors every day, so it is necessary to maintain the health of the indoor environment. Therefore, forming a good indoor air environment is an important guarantee for maintaining normal living. Formaldehyde, as a typical indoor pollutant, can cause a series of problems in the human respiratory system, immune system, and skin. Photocatalytic oxidation technology is a very promising indoor air purification technology developed in recent years. Its conversion is a process of converting pollutants into harmless substances using nano photocatalysts under light conditions.

[0003] Alkali-activated cementitious materials (AACM) are a kind of green materials that can potentially replace Portland cement, with the advantages of low energy consumption, green environmental protection, and sustainable development. In addition, due to its similar zeolite ring molecular chain structure, it can be used as an adsorbent to remove indoor formaldehyde. However, the low porosity of AACM limits its adsorption of formaldehyde.

[0004] Foamed alkali-activated cementitious materials (FAACM) are prepared by introducing foam into AACM, which combines the advantages of AACM and traditional foam concrete. It not only has the advantages of traditional foam concrete such as energy saving, waste utilization, and strong adsorption, but also has excellent mechanical properties and corrosion resistance due to the high strength and corrosion resistance of AACM. The high pore structure of FAACM improves the adsorption efficiency of formaldehyde, and at the same time makes it possible to become a photocatalyst carrier. However, attaching photocatalysts with formaldehyde degradation function, such as nano TiO2, directly to AACM or FAACM restricts its catalytic degradation efficiency due to the wide band gap of nano TiO2 and the rapid recombination of photo-generated electrons and holes. Moreover, due to the high porosity of FAACM, the mechanical strength is lost while improving the adsorption and removal of formaldehyde performance.

[0005] Therefore, it is of great practical significance to develop a kind of foamed alkali-activated cementitious material that simultaneously has strength and formaldehyde degradation function. SUMMARY

[0006] The content of the present application is to provide a method for preparing a foamed cementitious material by using fly ash of a coal-fired power plant, to source utilization of fly ash and blast furnace slag and magnesium slag, to reduce landfill accumulation of solid waste, and to provide corresponding technical support for functional application of green building materials. The present application prepares a light foamed alkali-activated cementitious material (FAACM) by adding a foaming agent, prepares a gelled nano photocatalyst, and attaches the gelled nano photocatalyst to the FAACM by a blending method, so that the material has good mechanical strength and a function of degrading formaldehyde.

[0007] The present application achieves the above-mentioned purpose through the following technical solutions:

[0008] A foamed alkali-activated cementitious material is composed of an intermediate layer and surface layers covering the upper and lower surfaces of the intermediate layer, and the intermediate layer and the surface layers comprise the following raw materials: 30-50 parts by mass of blast furnace slag, 12-18 parts by mass of low-calcium fly ash, 9-15 parts by mass of alkaline magnesium slag, 10-15 parts by mass of an alkali activator, 6-8 parts by mass of a foaming agent, and 3-5 parts by mass of a foam stabilizer; the surface layers further comprise 1.5-5 parts by mass of a functional catalyst, and the functional catalyst is a gelled micro-nano TiO2 particle.

[0009] Preferably, the surface layers further comprise 2-3 parts by mass of a functional catalyst.

[0010] Preferably, the thickness of the intermediate layer is 30-50 mm, and the thickness of the surface layer is 5-10 mm.

[0011] Further, the gelled micro-nano TiO2 particle is prepared by a sol-gel method under acidic conditions in the presence of an alkyl titanate, an alcohol, and water; preferably, the alkyl titanate is at least one of n-butyl titanate and tetrabutyl titanate; the alcohol is at least one of methanol and ethanol; and the acid is at least one of hydrochloric acid, hydrobromic acid, and hydroiodic acid.

[0012] Further, the foaming agent is at least one of hydrogen peroxide and aluminum powder, and the foam stabilizer is at least one of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, hydroxypropyl methylcellulose ether, and polyacrylamide.

[0013] Preferably, the foaming agent is aluminum powder. The inventors have found that, in addition to participating in the chemical foaming process, the excess aluminum powder can also participate in the geopolymerization reaction, thereby generating more C-A-S-H gel and providing more structural support while generating a large number of bubbles, so as to improve the mechanical properties of the prepared foamed alkali-activated cementitious material.

[0014] Preferably, the blast furnace slag has a specific surface area of 400-650 m 2More preferably, the blast furnace slag comprises the following mass percentages of components: 27-33wt% SiO2, 17-20wt% Al2O3, 0.4-0.6wt% Na2O, 35-40wt% CaO, 6-8wt% MgO.

[0015] Preferably, the low calcium fly ash is obtained from the fine ash collected by coal-fired power plants from flue gas. More preferably, the fly ash comprises the following mass percentages of components: 45-55wt% SiO2, 32-37wt% Al2O3, 0.8-1.1wt% Na2O, 3.5-5wt% CaO, 0.6-0.9wt% MgO.

[0016] Preferably, the magnesium slag is a residue from the slag of the Pidgeon process for magnesium production. More preferably, the magnesium slag comprises the following mass percentages of components: 30-40wt% SiO2, 0.5-3wt% Al2O3, 40-50wt% CaO, 8-13wt% MgO, 3-9wt% Fe2O3.

[0017] Preferably, the alkali activator is a mixture of water glass (Na2O-nSiO2) and NaOH in a mass ratio of 3-6:1, the modulus n of the alkali activator being 1.0-3.0; preferably 1.5-2.0. More preferably, the mass ratio of water glass and NaOH is 4-5:1.

[0018] The functional photocatalyst is obtained by a preparation method comprising the following steps:

[0019] (T1) 70-100 parts of ethanol, 5-10 parts of water, 3-5 parts of hydrochloric acid are configured into solution A according to mass fraction;

[0020] (T2) 40-50 parts of alkyl titanate and 60-70 parts of ethanol are configured into solution B according to mass fraction;

[0021] (T3) Solution A is slowly added to solution B, when the solution presents a gel-like state, 5-10 parts of hydroiodic acid in ethanol solution is added, stirring for 15 min, 15-20 parts of low calcium fly ash is added to the sol, ultrasonic dispersion for 30 min at a constant temperature of 25°C. 3-5 parts of deionized water is added at a rate of 0.5 mL / min until gel-like micro-nano TiO2 particles are obtained.

[0022] The application prepares the foam alkali-activated cementitious material with excellent mechanical properties by chemical foaming. The aluminum powder is used as the foaming agent, and the sodium dodecyl benzene sulfonate is used as the foam stabilizer, so that a large number of pore structures can be effectively formed, and the generation of the C-A-S-H gel is increased, thereby overcoming the problem of low mechanical strength of the foam alkali-activated cementitious material, and making the foam alkali-activated cementitious material have a wider application space. The functional catalyst, i.e., the nano TiO2 hydrophobic gel, is prepared by the sol-gel method. The n-butyl titanate is dissolved in the ethanol solvent, and then mixed with the deionized water to perform the hydrolysis and condensation reaction, so that the titanium dioxide particles formed at the beginning can be effectively avoided from agglomerating into large particles. Then, the physical compression effects such as centrifugation and solvent evaporation are used to force the colloidal particles to be close to each other, overcome the repulsion, and realize the gelation. The photocatalyst can be well attached to the three-dimensional network zeolite structure of the matrix material, so that the single-particle TiO2 is formed, and the photocatalyst can be uniformly distributed on the matrix material without destroying the basic structure of the matrix material. The gel-like micro-nano TiO2 particles also effectively avoid being separated from the three-dimensional network of the matrix material, prolong the service life of the composite material, and ensure the stability of the photocatalytic composite material. The porous structure of the foam alkali-activated cementitious material enhances the adsorption effect on the formaldehyde gas, further increases the contact area between the formaldehyde gas and the functional catalyst, and thereby improves the degradation efficiency.

[0023] The application further provides a preparation method of the foam alkali-activated cementitious material, which comprises the following steps:

[0024] (S1) according to the mass fraction, the slag, fly ash, magnesium slag, alkali activator, foaming agent, foam stabilizer, are added into a stirring tank to obtain slurry I; according to the mass fraction, the slag, fly ash, magnesium slag, alkali activator, foaming agent, foam stabilizer, functional catalyst, are added into a stirring tank to obtain slurry II;

[0025] (S2) the slurry I is prepared into an intermediate layer by the 3D printing method or the template method, and the surface layer is prepared on the upper and lower surfaces of the intermediate layer by using the slurry II; and the alkali-activated cementitious material is obtained by curing at room temperature.

[0026] The process for preparing the three-layer sandwich structure gel material by the 3D printing method or the template method is well known in the art.

[0027] The application further provides the application of the foam alkali-activated cementitious material as a building material.

[0028] For example, for the template method, the slurry I is poured into the mold of the place where the acrylic plate is placed, leaving a certain gap, and then the slurry II is continuously poured, and then the mold is turned over, the acrylic plate is pulled out, and the slurry II is poured to form a sandwich structure, the slurry I as the intermediate layer material, and the slurry II as the surface layer material on the upper and lower surfaces of the intermediate layer. The addition amount of slurry I and slurry II is controlled to make the thickness of the intermediate layer 30-50mm, and the thickness of the surface layer 5-10mm.

[0029] For the 3D printing method, the slurry I is poured on the experimental table through the 3D printing nozzle, and when the thickness is 5-10mm, the slurry II is poured as the intermediate layer on the slurry I through the 3D printing nozzle, and the thickness is 30-50mm. Finally, the remaining slurry I is poured in the same way to form a sandwich structure.

[0030] The beneficial effects of the present application relative to the prior art are:

[0031] (1) The present application uses fly ash, magnesium slag and slag and other accumulated solid wastes to prepare energy-saving green building materials with the ability to degrade formaldehyde. Compared with traditional porous foam materials, the foam alkali activated cementitious material prepared by using aluminum powder as a foaming agent not only has the advantage of using industrial by-products, but also produces a dense and uniform pore structure, which is beneficial to the adsorption of formaldehyde gas. Moreover, it can also participate in the geological polymerization reaction to generate more gel structure, providing better mechanical properties for the composite material.

[0032] (2) The photocatalyst of the present application is specially treated to make it play a better role in the degradation of formaldehyde gas under natural light conditions. The specially treated photocatalyst can maintain good stability during the geological polymerization process and will not cause mass loss in the alkaline environment. At the same time, the specially treated photocatalyst can be well dressed in the three-dimensional network-like zeolite structure of the matrix material, ensuring the stability of the photocatalytic composite material. At the same time, the porous structure of the matrix material further enhances the adsorption and sealing capacity of formaldehyde gas, effectively avoiding the escape of formaldehyde gas, thereby increasing the contact efficiency of the photocatalyst and the target degradation pollutant formaldehyde, and improving the degradation efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 is a TEM photo of the gel-like micro-nano TiO2 particles prepared in Preparation Example 1;

[0034] Figure 2 is a SEM image and a TEM image of the functional alkali activated cementitious material obtained in Example 1;

[0035] Figure 3is a macroscopic photo of the sandwich structure formaldehyde degradation functional base-activated material of examples 1-5, and no functional catalyst is added;

[0036] Figure 4 is the SEM image and TEM image of the functional base-activated cementitious material obtained in comparative example 1. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described in detail below. The following examples facilitate better understanding of the present application, but do not limit the present application. The experimental methods in the following examples are all conventional methods, unless otherwise specified.

[0038] The reagents and raw materials used in the present application are all commercially available, blast furnace slag (BFS) is purchased from Tang Steel Company, fly ash (FA) is purchased from Henan Hengyuan New Material Co., Ltd., and magnesium slag (MS) is from Shaanxi Dongfeng Magnesium Co., Ltd. and Xilong Science and Technology Co., Ltd. The composition of blast furnace slag, fly ash and magnesium slag is analyzed by XRF-1800 continuous X-ray fluorescence spectrometer, and the results are shown in Table 1 below:

[0039] Table 1

[0040] Raw materials SiO2(wt%) Al2O3 (wt%) Na2O (wt%) CaO (wt%) MgO (wt%) F2O3 (wt%) BFS 31.59 18.79 0.45 37.59 7.32 0.319 FA 50.28 35.56 0.964 4.06 0.715 6.39 MS 38.43 0.95 / 43.79 9.65 4.51

[0041] Preparation Example 1

[0042] (T1), according to the mass fraction, 100 parts of ethanol, 10 parts of water, 3 parts of hydrochloric acid are configured into solution A.

[0043] (T2), according to the mass fraction, including 50 of n-butyl titanate, 70 parts of ethanol are configured into solution B.

[0044] (T3), solution A is slowly added to solution B, when the solution presents a gel, 10 parts of hydroiodic acid in ethanol solution is added, stirred for 15 min, 20 parts of low calcium fly ash is added, ultrasonic dispersion is carried out at constant temperature 25℃ for 30 min, 5 parts of deionized water is added at a rate of 0.5 mL / min until gel-like micro-nano TiO2 particles are obtained, which are functional catalysts.

[0045] Figure 1 is a TEM photo of the gel-like micro-nano TiO2 particles prepared in preparation example 1, it can be seen that the TiO2 hydrophobic gel does not agglomerate with each other, but presents uniform dispersion.

[0046] Preparation Example 2

[0047] (T1), according to the mass fraction, 70 parts of ethanol, 5 parts of water, 5 parts of hydrochloric acid are configured into solution A.

[0048] (T2), n-butyl titanate 30 parts by mass, ethanol 60 parts by mass were configured into solution B.

[0049] (T3), solution A was slowly added to solution B, when the solution showed gel-like, a solution containing 10 parts of hydroiodic acid in ethanol was added, stirred for 15 min, 15 parts of low calcium fly ash was added, ultrasonic dispersion for 30 min at 25℃, 3 parts of deionized water was added at a rate of 0.5 mL / min until the gel-like micro-nano TiO2 particles were obtained as a functional catalyst.

[0050] Example 1

[0051] A preparation method of a sandwich structure formaldehyde degradation functional alkali-activated material, comprising the following steps:

[0052] S1: Collecting blast furnace slag discharged from an iron smelting plant; grinding the blast furnace slag in a planetary ball mill; adding 40 parts by mass of slag, 15 parts by mass of fly ash, 12 parts by mass of magnesium slag, 12 parts by mass of alkali activator (which is composed of 4 parts of water glass, 1 part of NaOH and 8 parts of water, and the modulus n is 1.5), 6 parts by mass of aluminum powder, and 3 parts by mass of sodium dodecyl benzene sulfonate into a stirring tank to obtain slurry I; adding 40 parts by mass of slag, 15 parts by mass of fly ash, 12 parts by mass of magnesium slag, 12 parts by mass of alkali activator, 1.5 parts by mass of the functional catalyst prepared in Preparation Example 1, 6 parts by mass of aluminum powder, and 3 parts by mass of sodium dodecyl benzene sulfonate into a stirring tank to obtain slurry II;

[0053] (S2) Pouring slurry I into a mold with a size of 40mm×40mm×40mm, placing a 5mm acrylic plate at the bottom of the mold, controlling the amount of slurry I added to make the middle layer thickness 30mm, leaving a 5mm gap at the top of the mold, pouring slurry II to form a 5mm surface layer, then turning over the mold, removing the acrylic plate, and pouring slurry II to form a 5mm surface layer on the upper and lower surfaces of the middle layer. After curing at room temperature for 7 days, a sandwich structure formaldehyde degradation functional alkali-activated building material with a middle layer thickness of 30mm and a surface layer thickness of 5mm was obtained.

[0054] Figure 2 are SEM and TEM images of the foam functional alkali-activated building material obtained in Example 1, from which it can be seen that TiO2 hydrophobic gel is uniformly dispersed in the matrix material.

[0055] Example 2

[0056] The other operations and conditions are the same as in Example 1, except that the amount of functional catalyst added to slurry II is 2 parts by mass.

[0057] Example 3

[0058] Other operations and conditions are the same as example 1, except that the functional catalyst is added in the amount of 3 parts by mass in mortar II.

[0059] Example 4

[0060] Other operations and conditions are the same as example 1, except that the functional catalyst is added in the amount of 4 parts by mass in mortar II.

[0061] Example 5

[0062] Other operations and conditions are the same as example 1, except that the functional catalyst is added in the amount of 5 parts by mass in mortar II.

[0063] Figure 3 are macroscopic photographs of sandwich structure formaldehyde degradation functional alkali activated materials of examples 1-5, and a sandwich structure formaldehyde degradation functional alkali activated material without adding a functional catalyst, wherein (a) is without adding a functional catalyst, (b) to (f) are materials prepared by examples 1-5, respectively. It can be seen that due to the addition of the foaming agent aluminum powder, the obtained foamed alkali activated cementitious material is a porous material; and whether the functional catalyst is added or not, and the amount of the functional catalyst added has no significant effect on the macrostructure of the material.

[0064] Example 6

[0065] Other operations and conditions are the same as example 3, except that the functional catalyst is prepared in preparation example 2.

[0066] 30-50 parts by mass of blast furnace slag, 12-18 parts by mass of low calcium fly ash, 9-15 parts by mass of alkaline magnesium slag, 10-15 parts by mass of alkali activator; the surface layer further comprises 3-5 parts by mass of a functional catalyst, 6-8 parts by mass of a foaming agent, 3-5 parts by mass of a foam stabilizer, and the functional catalyst is gel-like micro-nano TiO2 particles.

[0067] Example 7

[0068] Other operations and conditions are the same as example 3, except that the raw materials of mortar I are 30 parts by mass of slag, 18 parts by mass of fly ash, 9 parts by mass of magnesium slag, and 10 parts by mass of alkali activator; the raw materials of mortar II are 30 parts by mass of slag, 18 parts by mass of fly ash, 9 parts by mass of magnesium slag, 10 parts by mass of alkali activator, 3 parts by mass of the functional catalyst prepared in preparation example 1, 7 parts by mass of hydrogen peroxide, and 3 parts by mass of hydroxypropyl methyl cellulose ether.

[0069] Example 8

[0070] Other operations and conditions are the same as example 3, the difference is that the raw materials of mortar I are 50 parts by mass of slag, 12 parts by mass of fly ash, 15 parts by mass of magnesium slag, 15 parts by mass of alkali activator, 8 parts by mass of aluminum powder, and 5 parts by mass of sodium dodecyl sulfate; the raw materials of mortar II are 50 parts by mass of slag, 12 parts by mass of fly ash, 15 parts by mass of magnesium slag, 15 parts by mass of alkali activator, 8 parts by mass of aluminum powder, 5 parts by mass of sodium dodecyl sulfate, and 3 parts by mass of the functional catalyst prepared in Preparation Example 1.

[0071] Comparative Example 1

[0072] Other operations and conditions are the same as example 3, the difference is that the functional catalyst is anatase nano-titanium dioxide, and the amount of the functional catalyst added is such that the content of TiO2 in the surface layer is the same as that of example 2.

[0073] Figure 4 The SEM and TEM images of the functional alkali-activated cementitious material obtained in Comparative Example 1 are shown in FIGS. 1 and 2, respectively, from which it can be seen that the unmodified nano-TiO2 particles are agglomerated on the matrix material.

[0074] Comparative Example 2

[0075] The inventors also tried to use a physical foaming method, in which a foaming agent (a mixture of sodium dodecyl benzene sulfonate and tea saponin in a mass ratio of 4:1) was used to prepare a foam through an air compressor, and the foam was added to the mixer under stirring conditions while mixing with other materials. However, the mechanical strength of the obtained gel material at the same density was low, with a maximum of only about 15 MPa. Moreover, the physical foaming was not uniform, resulting in a large fluctuation in strength even for the same batch of samples. The present application uses chemical foaming, and the foaming speed is uniform and moderate, and the foam is more uniformly and stably dispersed.

[0076] Performance test

[0077] Using the samples provided in the examples and comparative examples, the compressive strength of the samples with an age of 3d and 7d was tested according to GB / T 17671-1999 using a microcomputer-controlled electronic universal testing machine (CMT4304) with a loading area of 40mm x 40mm and a loading rate of 5mm / min. The formaldehyde degradation experiment was carried out by heating the output formaldehyde gas at 80℃ in a water bath, feeding it into the reactor through a gas supply system, and using the gel material cured for 7d under simulated solar light irradiation with an input power of 500W, with an initial formaldehyde concentration of 50ppm, using a suction pump type formaldehyde detector to test the formaldehyde concentration, calculate the formaldehyde degradation efficiency, and maintain the light irradiation time to 10d, monitor the change of formaldehyde degradation efficiency, the results are shown in Table 2:

[0078] Table 2 Performance indicators of catalyst-cementitious material

[0079]

[0080] As can be seen from Table 2, with the increase of the amount of functional additive, the degradation rate of formaldehyde is increased, and the mechanical strength of the foamed gel material is increased, which is probably due to the fact that the gel-like micro-nano TiO2 particles are filled in the voids of the geopolymer, inhibiting the crack initiation and making the geopolymer structure more compact, thereby improving the compressive strength of the material. However, when the amount of functional additive is too much, the mechanical strength of the foamed gel material will decrease, which is due to the fact that the dispersion of the gel-like micro-nano TiO2 particles in the matrix material is poor because of the increase of the content of the gel-like micro-nano TiO2 particles, and the special structure of the gel-like micro-nano TiO2 particles hinders the movement of the fluid in the slurry, resulting in insufficient geopolymerization. Although the addition of the foaming agent to prepare the porous foamed alkali-activated gel material (FAACM) will reduce the mechanical strength to a certain extent, the porous structure formed will make the gel material have a small density, and the gel material is a lightweight building material. On the other hand, the presence of the porous structure is also beneficial to the adsorption and degradation of formaldehyde, and is more conducive to the removal of formaldehyde gas. In some fields that do not require high strength, the foamed gel material of the present application can be used instead of the gel material.

Claims

1. A foam-activated cementitious material, comprising an intermediate layer and surface layers covering the upper and lower surfaces of the intermediate layer, characterized in that, The intermediate layer comprises the following raw materials: 30-50 parts by weight of blast furnace slag, 12-18 parts by weight of low-calcium fly ash, 9-15 parts by weight of alkaline magnesia slag, 10-15 parts by weight of alkali activator, 6-8 parts by weight of foaming agent, and 3-5 parts by weight of foam stabilizer; the surface layer comprises the following raw materials: 40 parts by weight of blast furnace slag, 15 parts by weight of low-calcium fly ash, 12 parts by weight of alkaline magnesia slag, 12 parts by weight of alkali activator, 6 parts by weight of foaming agent, 3 parts by weight of foam stabilizer, and 2-3 parts by weight of functional catalyst; the functional catalyst is gel-like micro / nano TiO2 particles; the functional catalyst is obtained by a preparation method including the following steps: (T1) Prepare solution A by mixing 70-100 parts of ethanol, 5-10 parts of water, and 3-5 parts of hydrochloric acid according to the mass fraction. (T2) Solution B is prepared by mass fractions including 40-50 parts of alkyl titanate and 60-70 parts of ethanol; (T3) Slowly add solution A to solution B. When the solution becomes gel-like, add an ethanol solution containing 5-10 parts of hydroiodic acid and stir for 15 min. Add 15-20 parts of low-calcium fly ash to the sol and sonicate at a constant temperature of 25℃ for 30 min. Add 3-5 parts of deionized water at a rate of 0.5 mL / min until gel-like micro-nano TiO2 particles are obtained.

2. The foam-activated cementitious material according to claim 1, characterized in that, The thickness of the intermediate layer is 30-50 mm, and the thickness of the surface layer is 5-10 mm.

3. The foam alkali-activated cementitious material according to claim 1, characterized in that, The foaming agent is selected from at least one of hydrogen peroxide and aluminum powder; the foam stabilizer is selected from at least one of sodium dodecylbenzenesulfonate, sodium dodecyl sulfate, hydroxypropyl methylcellulose ether, and polyacrylamide.

4. The foam-activated cementitious material according to claim 1, characterized in that, The blast furnace slag has a specific surface area of ​​400~650 m². 2 / kg; The low-calcium fly ash comprises the following components by mass percentage: 45-55 wt% SiO2, 32-37 wt% Al2O3, 0.8-1.1 wt% Na2O, 3.5-5 wt% CaO, and 0.6-0.9 wt% MgO. The alkaline magnesium slag comprises the following components by mass percentage: 30-40 wt% SiO2, 0.5-3 wt% Al2O3, 40-50 wt% CaO, 8-13 wt% MgO, and 3-9 wt% Fe2O3.

5. The foam-activated cementitious material according to claim 4, characterized in that, Blast furnace slag comprises the following components by mass percentage: 27-33 wt% SiO2, 17-20 wt% Al2O3, 0.4-0.6 wt% Na2O, 35-40 wt% CaO, and 6-8 wt% MgO.

6. The foam alkali-activated cementitious material according to claim 1, characterized in that, The alkaline activator is a mixed aqueous solution of water glass and NaOH prepared in a mass ratio of 3-6:1, and the modulus n of the alkaline activator is 1.0~3.

0.

7. The foam-activated cementitious material according to claim 6, characterized in that, The modulus n of the alkaline activator is 1.5~2.

0.

8. The foam alkali-activated cementitious material according to claim 6, characterized in that, The mass ratio of water glass to NaOH is 4-5:

1.

9. The method for preparing the foam alkali-activated gelling material according to any one of claims 1-8, characterized in that, Includes the following steps: (S1) According to the mass fractions, blast furnace slag, low-calcium fly ash, basic magnesium slag, alkali activator, foaming agent, and foam stabilizer are added to the mixing tank to obtain mortar I; according to the mass fractions, blast furnace slag, low-calcium fly ash, basic magnesium slag, alkali activator, foaming agent, foam stabilizer, and functional catalyst are added to the mixing tank to obtain mortar II; (S2) Mortar I is prepared into an intermediate layer by 3D printing or template method, and mortar II is used to prepare a surface layer on the upper and lower surfaces of the intermediate layer; the alkali-activated cementitious material is obtained by curing at room temperature.

10. The use of the foamed alkali-activated cementitious material according to any one of claims 1-8 as a building material.

Images