A geopolymer recycled fireproof mortar reinforced with waste glass powder and its preparation method

Abstract

The present invention discloses a geopolymer recycled fireproof mortar reinforced with waste glass powder and a preparation method thereof. The recycled fireproof mortar concrete is made from the following raw material components: 480 - 500 parts of a gelling material, 840 - 1080 parts of recycled fine aggregate, 310 - 340 parts of an alkali activator, 120 - 360 parts of waste glass powder, and 50 parts of water. The preparation method is as follows: The recycled fine aggregate is mixed and stirred with the gelling material to obtain a dry mix; the waste glass powder and the alkali activator are stirred and pre-treated to obtain an alkali-activated mixed solution; the alkali-activated mixed solution is added to the dry mix and stirred to obtain a mortar slurry; the mortar slurry is poured into a mold, and during the pouring process, it is tamped and vibrated layer by layer. After the surface solidifies, the mold is wrapped, and cured to obtain the geopolymer recycled fireproof mortar. The present invention completely uses recycled aggregate, and on this basis, uses waste glass powder to partially replace the recycled fine aggregate, alleviating the problem of resource shortage caused by over-exploitation of natural sand. By utilizing the synergistic reaction between the waste glass powder and the geopolymer and its filling effect, the problem of poor performance of the recycled mortar can be effectively alleviated, and the workability and fireproof performance of the geopolymer recycled mortar can be improved.

Description

Technical Field

[0001] The invention belongs to the field of building materials, and in particular relates to a waste glass powder reinforced geopolymer recycled fireproof mortar and a preparation method thereof. Background Art

[0002] Red mud is industrial solid waste discharged when the aluminum industry extracts alumina. It contains a large amount of iron oxide and looks similar to red soil, so it is called red mud. About 1.0 to 1.8 tons of red mud are discharged for every ton of alumina produced. Efficient treatment of waste glass has become a key difficulty in the field of construction waste disposal. It is urgent to develop a technology for the reuse of waste glass and its related products.

[0003] Geopolymers have the characteristics of fast hardening, good fire resistance, high strength, acid corrosion resistance, etc., and SiO2 in waste glass can react synergistically with geopolymers. Waste glass dissolves silicon phase in an alkaline environment, and the quartz produced after hydration is the main component supporting the strength of geopolymers. Therefore, adding waste glass to geopolymers has a certain positive effect.

[0004] In recent years, building fires have occurred frequently, causing huge property losses and casualties. In order to improve the fire resistance of building structures, it is usually used to apply fire-retardant coatings on the surface. However, common thermal insulation coatings are expensive and excessive traditional thermal insulation coatings are prone to produce toxic smoke in fires, causing serious environmental pollution. It is of great value to develop a low-cost and environmentally friendly building fire-retardant coating. Summary of the invention

[0005] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0006] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a geopolymer recycled fireproof mortar reinforced with waste glass powder.

[0008] In order to solve the above technical problems, the present invention provides the following technical solution: In parts by weight, the geopolymer regenerated fireproof mortar comprises:

[0009] 480-500 parts of cementitious materials, 840-1080 parts of recycled fine aggregate, 310-340 parts of alkali activator, 120-360 parts of waste glass powder and 50 parts of water;

[0010] Among them, the cementitious material is red mud, which is an industrial solid waste discharged during the extraction of alumina in the aluminum industry; the waste glass powder is obtained by grinding waste glass into powder, meeting the requirements of waste recycling and reuse.

[0011] As a preferred embodiment of the geopolymer recycled fireproof mortar reinforced with waste glass powder according to the present invention, wherein: the recycled fine aggregate is a substandard product, with a water absorption rate of 8.8% and an apparent density of 2396 kg / m 3 .

[0012] As a preferred embodiment of the geopolymer recycled fireproof mortar reinforced with waste glass powder according to the present invention, wherein: the alkali activator is a mixed solution of NaOH solution and Na2SiO3 solution, and the mass ratio of the NaOH solution to the Na2SiO3 solution is 1:1.8 - 2.2.

[0013] As a preferred embodiment of the geopolymer recycled fireproof mortar reinforced with waste glass powder according to the present invention, wherein: the mass ratio of the alkali activator solution to the cementitious material is 0.6 - 0.7:1.

[0014] As a geopolymer recycled fireproof mortar reinforced with waste glass powder according to the present invention, wherein: the concentration of the NaOH solution is 10 mol / L, and the content of Na2O·nSiO2 in the Na2SiO3 solution is 42%, where the modulus n = 2.3.

[0015] As a preferred embodiment of the geopolymer recycled fireproof mortar reinforced with waste glass powder according to the present invention, wherein: the main component of the waste glass powder is SiO2, containing a small amount of Na2SiO3 and CaSiO3.

[0016] Another object of the present invention is to overcome the deficiencies in the prior art and provide a preparation method of a geopolymer recycled fireproof mortar reinforced with waste glass powder.

[0017] To solve the above technical problems, the present invention provides the following technical solutions:

[0018] Mix and stir the recycled fine aggregate and the cementitious material to obtain a dry mix;

[0019] Stir the waste glass powder and the Na2SiO3 solution to obtain a Na2SiO3 mixed solution;

[0020] Add the NaOH solution and the Na2SiO3 mixed solution to the dry mix in sequence to obtain the geopolymer recycled fireproof mortar.

[0021] As a preferred embodiment of the preparation method of the geopolymer recycled fireproof mortar reinforced with waste glass powder according to the present invention, wherein: the stirring time for mixing and stirring the recycled fine aggregate and the cementitious material is 30 - 45 s.

[0022] As a preferred embodiment of the preparation method of the geopolymer recycled fireproof mortar reinforced with waste glass powder according to the present invention, wherein: the stirring time for mixing the waste glass powder and the Na2SiO3 solution is 60 s

[0023] As a preferred embodiment of the preparation method of the geopolymer fireproof mortar based on waste porous materials according to the present invention, wherein: the stirring time for adding the NaOH solution to the dry mix is 30 s, and the stirring time for adding the Na2SiO3 mixed solution is 150 - 180 s

[0024] Advantages of the present invention:

[0025] The present invention uses red mud as a cementitious material to prepare geopolymer recycled fireproof mortar, which has good mechanical and working properties. Recycling red mud can effectively alleviate the environmental pollution caused by red mud, and has significant economic and social benefits. At the same time, recycled aggregates are completely used, and waste glass powder is used to partially replace recycled fine aggregates on this basis, alleviating the problem of resource shortage caused by over-exploitation of natural sand. By utilizing the synergistic reaction between waste glass powder and geopolymer and its filling effect, the problem of poor performance of recycled mortar can be effectively alleviated, and the working performance and fireproof performance of geopolymer recycled mortar can be improved Description of the drawings

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts. Among them:

[0027] Figure 1 Schematic diagram of the geopolymer recycled fireproof mortar test block in the embodiment of the present invention

[0028] Figure 2 XRD diagram of the geopolymer recycled fireproof mortar test block after the simulated fire experiment in Embodiment 1 of the present invention

[0029] Figure 3 Scanning electron microscope images of the geopolymer recycled fireproof mortar test blocks in Comparative Example 1 and Embodiment 1 of the present invention after the simulated fire experiment Detailed implementation manners

[0030] To make the above objects, features and advantages of the present invention more obvious and understandable, the detailed implementation manners of the present invention will be described in detail below in conjunction with the embodiments of the specification

[0031] In the following description, numerous specific details are set forth to provide a thorough understanding of the present invention. However, the present invention may be practiced in other ways than those specifically described herein. Those skilled in the art can make similar extensions without departing from the spirit of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.

[0032] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation manner of the present invention. The phrase "in one embodiment" appearing in different places in this specification does not necessarily refer to the same embodiment, nor is it an individual or alternative embodiment that is mutually exclusive with other embodiments.

[0033] The recycled fine aggregate used in the embodiments of the present invention is a substandard product, with a water absorption rate of 8.8% and an apparent density of 2396 kg / m 3 .

[0034] The waste glass powder used in the embodiments of the present invention is obtained by grinding waste glass into powder, meeting the requirements of waste recycling. Most of the particle sizes of the waste glass powder are 1250 mesh.

[0035] When conducting a fire simulation experiment on the geopolymer recycled fireproof mortar, the set temperature is 800 °C and the duration is 2 h. The residual compressive strength and mass loss rate of the mortar specimens after the simulation experiment are measured.

[0036] Example 1

[0037] This embodiment provides a preparation method of a geopolymer recycled fireproof mortar, including the following steps:

[0038] (1) Weigh the raw materials according to the following formula:

[0039] 480 parts of a gelling material (red mud), 1080 parts of recycled fine aggregate, 320 parts of an alkali activator (95 parts of NaOH solution and 225 parts of Na2SiO3 solution), 120 parts of waste glass powder, and 50 parts of water

[0040] Among them, the concentration of the NaOH solution is 10 mol / L, the content of Na2O·nSiO2 in the Na2SiO3 solution is 42%, where the modulus n = 2.3, the content of Fe2O3 in the red mud is 12.15%, and the apparent density is 2596 kg / m 3 .

[0041] (2) Prepare the mortar slurry:

[0042] Mix and stir the recycled fine aggregate and the gelling material (red mud) for 30 s to obtain a dry mixture;

[0043] Stir the waste glass powder with the Na2SiO3 solution for 60 s to obtain the Na2SiO3 mixed solution;

[0044] Slowly add the NaOH solution along the edge of the blender to the dry mixture and stir for 30 s. Immediately afterwards, slowly add the Na2SiO3 mixed solution and stir for 120 s to obtain the mortar slurry.

[0045] (3) Spray the release agent in the mold, fill the geopolymer recycled fireproof mortar slurry into the mold, compact it layer by layer during the mold filling process, then place it on the vibrating table and vibrate for 15 s, smooth the surface, and wrap the mold with a plastic film after the surface solidifies.

[0046] (4) After demolding, seal the geopolymer fireproof mortar specimens with a sealed bag and place them in a standard curing room (temperature 20 ± 2 °C, relative humidity ≥ 95%) for 1 d. After the curing is completed, place them in an oven for high-temperature curing at 105 °C for 1 d. After the high-temperature curing is completed, wait for the specimens to cool to room temperature, open the sealed bag, take out the specimens, and place them in the standard curing room for continued curing for 3 d to obtain the mortar specimens of this example.

[0047] Example 2

[0048] The difference between this example and Example 1 is that the raw material formula in step (1) is as follows:

[0049] 485 parts of cementitious material (red mud), 960 parts of recycled fine aggregate, 330 parts of alkali activator (95 parts of NaOH solution, 235 parts of Na2SiO3 solution), 240 parts of waste glass powder, and 50 parts of water.

[0050] The remaining steps are the same as those in Example 1 to obtain the mortar specimens of this example.

[0051] Example 3

[0052] The difference between this example and Example 1 is that the raw material formula in step (1) is as follows:

[0053] 500 parts of cementitious material (red mud), 840 parts of recycled fine aggregate, 340 parts of alkali activator (95 parts of NaOH solution, 245 parts of Na2SiO3 solution), 360 parts of waste glass powder, and 50 parts of water.

[0054] The remaining steps are the same as those in Example 1 to obtain the mortar specimens of this example.

[0055] The properties of the fireproof mortar specimens prepared in Examples 1 to 3 were tested. According to GB / T 17671-2021 "Test Method for Strength of Cement Mortar", the compressive strength of the geopolymer recycled fireproof mortar was measured; according to GB / T 10294-2008 "Determination of Steady-State Thermal Resistance and Related Characteristics of Thermal Insulation Materials", the thermal conductivity of the geopolymer recycled fireproof mortar was measured; the test results are shown in Table 1.

[0056] Table 1 Performance test results of geopolymer recycled fireproof mortar specimens prepared with different formulations

[0057]

[0058] From the comparison results in Table 1, it can be seen that the loss rate of compressive strength of the geopolymer recycled fireproof mortar specimens prepared in the examples of the present invention after the fire simulation experiment is lower than 70%, and the mass loss rate after the fire simulation experiment is lower than 5%. The geopolymer recycled fireproof mortar specimens perform well in the fire simulation experiment.

[0059] Comparative Example 1

[0060] The difference between this comparative example and Example 1 is that in step (1), the waste glass powder is not added to the raw material formulation, specifically:

[0061] 480 parts of cementitious material (red mud), 1280 parts of recycled fine aggregate, 300 parts of alkali activator (95 parts of NaOH solution, 205 parts of Na2SiO3 solution).

[0062] The remaining steps are the same as those in Example 1 to prepare the mortar specimens of this comparative example.

[0063] Comparative Example 2

[0064] The difference between this comparative example and Example 1 is that in step (1), the dosage of the alkali activator in the raw material formulation is reduced, specifically:

[0065] 480 parts of cementitious material (red mud), 1080 parts of recycled fine aggregate, 300 parts of alkali activator (95 parts of NaOH solution, 205 parts of Na2SiO3 solution), 120 parts of waste glass powder and 50 parts of water.

[0066] The remaining steps are the same as those in Example 1 to prepare the mortar specimens of this comparative example.

[0067] The properties of the fireproof mortar specimens prepared in Comparative Examples 1 to 2 were tested and compared with those in Example 1. The results are shown in Table 2.

[0068] Table 2 Performance test results of geopolymer fireproof mortar specimens prepared with different raw materials

[0069]

[0070] As can be seen from the comparison results in Table 2, after the fire simulation experiment, the compressive strength and mass loss rate of the geopolymer fireproof mortar specimens prepared in Example 1 after the fire simulation experiment are lower than those in Comparative Example 1. This is because the silicon element in the waste glass powder participates in the geopolymerization reaction, enhancing the Si-Al structure in the geopolymer, thereby improving the strength and stability of the mortar. Moreover, the geopolymer itself exhibits excellent high-temperature resistance. The waste glass powder fills the pores formed by the recycled fine aggregate, improving the overall compactness of the geopolymer mortar specimens. Additionally, the waste glass powder can dissolve out the silicon phase in an alkaline environment and generate reyerite at high temperatures. This zeolite has a unique pore structure, and zeolite minerals have a relatively high melting point, which can improve the heat resistance of the sample and thus enhance the high-temperature resistance. By comparing Example 1 with Comparative Example 2, it can be found that adding waste glass powder will consume a part of the alkali activator in the geopolymer. Increasing the dosage of the alkali activator can make the SiO2 in the waste glass powder be more thoroughly activated, thereby exerting an enhancing effect on the recycled geopolymer fireproof mortar.

[0071] Comparative Example 3

[0072] The difference between this comparative example and Example 1 lies in adjusting step (2), specifically:

[0073] (2) The recycled fine aggregate, waste glass powder and cementitious material (red mud) are mixed and stirred for 60 s to obtain a dry mix.

[0074] The NaOH solution is slowly added along the edge of the mixer to the dry mix and stirred for 30 s. Immediately afterwards, the Na2SiO3 solution is slowly added and stirred for 120 s to obtain the mortar slurry.

[0075] The remaining steps are the same as those in Example 1 to prepare the mortar specimens of this comparative example.

[0076] Comparative Example 4

[0077] The difference between this comparative example and Example 1 lies in adjusting step (4), specifically:

[0078] (4) After demolding, the geopolymer fireproof mortar specimens are sealed with a sealed bag and placed in a standard curing room (temperature 20 ± 2 °C, relative humidity ≥ 95%) for 1 d. After the curing is completed, they are placed in an oven for high-temperature curing at 80 °C for 1 d. After the high-temperature curing is completed, when the specimens are cooled to room temperature, the sealed bag is opened, the specimens are taken out, and then placed in the standard curing room for continued curing for 3 d.

[0079] The remaining steps are the same as those in Example 1 to prepare the mortar specimens of this comparative example.

[0080] The properties of the fireproof mortar specimens prepared in Comparative Example 3 and Comparative Example 4 are tested and compared with those in Example 1. The results are shown in Table 3.

[0081] Table 3 Performance test results of geopolymer fireproof mortar specimens prepared by different processes

[0082]

[0083] It can be seen from the comparison results in Table 3 that the thermal conductivity of the geopolymer fireproof mortar specimen prepared in Comparative Example 3 is not much different from that in Example 1. However, the compressive strength and mass loss rate after the fire simulation experiment are much greater than those in Example 1. This is because the full stirring of waste glass powder and Na2SiO3 solution in advance can promote the alkali activation degree of waste glass powder, making it more likely to have a synergistic reaction with the alkali-activated cementitious system of geopolymer. Thus, more chabazite is generated in the high-temperature alkaline environment to fill the geopolymer structure, resulting in lower strength and mass loss. During the high-temperature curing process, the geopolymer recycled fireproof mortar specimen is sealed in a sealed bag, and the high-temperature environment can accelerate the progress of the hydration reaction. The specimen cured at 105°C is superior to that cured at 80°C, which is also related to the alkali activation of waste glass powder. A higher curing temperature not only speeds up the hydration reaction rate of geopolymer but also promotes the alkali activation degree of waste glass powder. After cooling to room temperature through high-temperature curing and then continuing to cure in a standard curing room for 3 days, the stability and durability of the mortar can be improved to ensure its long-term service performance.

[0084] Under the formulation of Example 1, NaOH solution and Na2SiO3 solution, as alkali activators, effectively promoted the hydration reaction of the cementitious material (red mud). From Figure 3 the scanning electron microscope images, it can be seen that after adding waste glass powder, the uncompletely alkali-activated glass powder is not useless but fills the micro-pores and micro-gaps inside the sample, making the structure denser and more stable. At the same time, combined with the preparation process of Example 1, the high-temperature environment can accelerate the progress of the hydration reaction, thus ensuring the full progress of the hydration reaction in the mortar specimen. From Figure 2 it can be seen that by pre-stirring waste glass powder and Na2SiO3 solution, the alkali activation degree of waste glass powder is accelerated, so that more chabazite is generated in the high-temperature environment to improve the thermal stability of the sample and the fire resistance of the mortar specimen.

[0085] Comparative Example 5

[0086] This comparative example is the aerogel fireproof mortar prepared according to the literature "Influence of Curing Environment on Fire Resistance of Aerogel Mortar Composite SCC Tunnels".

[0087] The performance of the fireproof mortar specimen prepared in Comparative Example 5 was tested and compared with that in Example 1. The results are shown in Table 4.

[0088] Table 4 Performance test results of geopolymer fireproof mortar specimens prepared by different methods

[0089]

[0090] Combined with the results in Table 4, it can be seen that the thermal conductivity of Comparative Example 5 is lower than that of Example 1. This is because the aerogel has extremely low thermal conductivity and density, causing a large number of incoherent air bubbles to fill the inside of the mortar specimen, thereby reducing the thermal conductivity. However, the low density also has certain drawbacks. From the strength and mass loss after the fire simulation experiment, it can be seen that although the thermal conductivity of Example 1 is higher than that of Comparative Example 5, it still exhibits superior fire resistance because more C-S-H crystals in the cement aerogel mortar exist in the form of tobermorite, and a large amount of dehydroxylation will occur above 700 °C, which will have a negative impact on the final fire resistance of the mortar.

[0091] The present invention prepares a geopolymer recycled fireproof mortar by using red mud as a gelling material, which has good mechanical and working properties. Recycling red mud can effectively alleviate the environmental pollution caused by red mud, and has significant economic and social benefits. At the same time, recycled aggregates are completely used, and waste glass powder is used to partially replace the recycled fine aggregates on this basis, alleviating the problem of resource shortage caused by over-exploitation of natural sand. In addition, by utilizing the synergistic reaction between waste glass powder and geopolymer and its filling effect, the problem of poor performance of recycled mortar can be effectively alleviated, and the working performance and fireproof performance of geopolymer recycled mortar can be improved.

[0092] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the present invention.

Claims

1. A geopolymer recycled fireproof mortar reinforced with waste glass powder, characterized in that: The geopolymer recycled fireproof mortar reinforced with waste glass powder is composed of the following raw materials in parts by weight: 480 - 500 parts of cementitious material, 840 - 1080 parts of recycled fine aggregate, 310 - 340 parts of alkali activator, 120 - 360 parts of waste glass powder, and 50 parts of water; The gelling material is red mud; the recycled fine aggregate is off-grade, with a water absorption rate of 8.8% and an apparent density of 2396 kg / m 3 ; the waste glass powder is obtained by grinding waste glass into a powder; The alkali activator is a mixed solution of NaOH solution and Na2SiO3 solution, wherein the mass ratio of NaOH solution to Na2SiO3 solution is 1:1.8 - 2.2; The preparation method of the geopolymer recycled fireproof mortar reinforced with waste glass powder includes, Mixing and stirring the recycled fine aggregate and the cementitious material to obtain a dry mix; Stirring the waste glass powder and the Na2SiO3 solution to obtain a Na2SiO3 mixed solution; Adding the NaOH solution and the Na2SiO3 mixed solution to the dry mix in sequence to obtain the geopolymer recycled fireproof mortar.

2. The geopolymer recycled fireproof mortar reinforced by waste glass powder according to claim 1, characterized in that: The concentration of the NaOH solution is 10 mol / L, and the content of Na2O·nSiO2 in the Na2SiO3 solution is 42%, where the modulus n = 2.

3.

3. The geopolymer recycled fireproof mortar reinforced with waste glass powder as claimed in claim 1, wherein: The main components of the red mud are: 44.36% CaO, 24.12% SiO2, 12.15% Fe2O3, 10.19% Al2O3; the main component of the waste glass powder is SiO2, containing a small amount of Na2SiO3 and CaSiO3.

4. The geopolmer recycled fireproof mortar reinforced with waste glass powder as claimed in claim 1, characterized in that: The stirring time for mixing and stirring the recycled fine aggregate and the cementitious material is 30 - 45 s.

5. The geopolymer recycled fireproof mortar reinforced with waste glass powder according to claim 1, wherein: The stirring time for stirring the waste glass powder and the Na2SiO3 solution is 60 s.

6. The geopolymer recycled fireproof mortar reinforced by waste glass powder as claimed in claim 1, wherein: Slowly add the NaOH solution to the dry mix and stir for 30 s, then add the Na2SiO3 mixed solution and stir for 150 - 180 s. After stirring is completed, immediately mold and cure to obtain the geopolymer recycled fireproof mortar.

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