Geopolymer-based aerogel fireproof coating, preparation method and application thereof

Abstract

The present application relates to the technical field of fireproof coating, and particularly relates to a geopolymer-based aerogel fireproof coating, a preparation method and application thereof. The fireproof coating comprises the following components in the following proportions: geopolymer precursor material, alkaline activator, aerogel, fiber and water; the mass ratio of the alkaline activator and the geopolymer precursor material is 0.52-0.63:1; the volume content of the aerogel is 70%-85%; the mass content of the fiber is 0-1% and is not 0; and the water-binder ratio is 0.5-0.7. The added fiber can effectively inhibit the high-temperature shrinkage of the coating, and at the same time, to a certain extent, improve the tensile strength and tensile bonding strength, so as to ensure the structural stability and continuous fireproofing capability of the coating in a fire scene; by optimizing the aerogel content and the water-binder ratio, the coating realizes an excellent balance between the thermal conductivity and the compressive strength, and has the characteristics of high strength and efficient heat insulation; the production process of the present application is low-carbon and environmentally friendly, and has economic and environmental benefits.

Description

Technical Field

[0001] This invention relates to the field of fire-retardant coating technology, and in particular to a geopolymer-based aerogel fire-retardant coating, its preparation method, and its application. Background Technology

[0002] As a common building structure, steel structures are widely used in high-rise buildings and large-span structures due to their advantages such as high strength, light weight, good seismic performance, and high recyclability. However, steel has poor fire resistance and a high thermal conductivity, causing the internal temperature of the components to rise rapidly in the event of a fire. Furthermore, steel has poor mechanical properties at high temperatures, which can easily lead to the overall collapse of the structure. Therefore, fire protection for steel structures is essential.

[0003] Currently, fire protection measures for steel structures include spraying fire-retardant coatings, covering with fire-resistant boards, covering with flexible felt-like insulation materials, external concrete cladding, metal mesh with mortar, or masonry construction. Among these, spraying fire-retardant coatings are the most widely used in practical engineering due to their adaptability to different component forms and ease of application. Fire-retardant coatings are generally divided into intumescent and non-intumescent fire-retardant coatings. Intumescent fire-retardant coatings, also known as thin-film fire-retardant coatings, are generally made of organic materials. Although they are relatively lightweight and aesthetically pleasing, their fire-retardant performance is limited and they may contain harmful components. In contrast, non-intumescent fire-retardant coatings are usually made of inorganic cementitious materials with added insulating fillers. They do not produce smoke or toxic gases during a fire and can effectively protect structural safety; however, they face the major problems of being prone to cracking and peeling.

[0004] Non-intumescent fire-retardant coatings are prone to peeling, primarily because the material's designed bond strength is relatively low. Current standards only require a bond strength greater than 0.04 MPa, which is insufficient to meet practical engineering needs. Furthermore, non-intumescent fire-retardant coatings are prone to significant shrinkage in dry environments, further exacerbating the risk of cracking and peeling, thus affecting the durability of their fire protection. Summary of the Invention

[0005] The purpose of this invention is to address the problems of easy cracking and easy peeling faced by non-intumescent fire-retardant coatings in the prior art, and to provide a geopolymer-based aerogel fire-retardant coating, its preparation method and application. By rationally selecting components and proportions and rationally setting the preparation process, multiple performance optimizations are achieved.

[0006] To achieve the above objectives, the present invention provides a geopolymer-based aerogel fire-retardant coating, comprising the following components in the following proportions:

[0007] Geopolymer precursor materials, basic activators, aerogels, fibers, and water;

[0008] The mass ratio of alkaline activator to geopolymer precursor material is 0.52-0.63:1; the volume content of aerogel is 70%-85%; the mass content of fiber is 0-1% and not zero; the water-gel ratio is 0.5-0.7.

[0009] Preferably, the geopolymer precursor materials include slag and fly ash, with a mass ratio of slag to fly ash of 5-7:3-5.

[0010] Preferably, the alkaline activator includes a sodium silicate solution with a mass concentration of 38%-42% and a modulus of 1.2-1.6.

[0011] Preferably, the aerogel comprises silica aerogel; the bulk density of the silica aerogel is 100 kg / m³. 3 -120kg / m 3 The specific surface area of ​​silica aerogel is 500 m². 2 / g-650m 2 / g, the porosity of silica aerogel is greater than 90%, and the pore size of silica aerogel is 20nm-100nm.

[0012] Preferably, the fiber comprises basalt fiber; the fiber length is 11mm-13mm, and the fiber diameter is... .

[0013] Preferably, the geopolymer-based aerogel fire-retardant coating also includes redispersible latex powder, wherein the mass content of the redispersible latex powder is 0-5% and not 0.

[0014] Preferably, the geopolymer-based aerogel fire-retardant coating also includes an expanding agent, wherein the mass content of the expanding agent is 0-6% and not 0.

[0015] The present invention also provides a method for preparing the aforementioned geopolymer-based aerogel fire-retardant coating, comprising the following steps:

[0016] The geopolymer precursor material and fiber are first mixed to obtain a first mixture; the first mixture, alkaline activator and water are second mixed to obtain a second mixture; the second mixture and aerogel are third mixed to obtain a geopolymer-based aerogel fire-retardant coating.

[0017] Preferably, before the first mixing of the geopolymer precursor material and the fiber to obtain the first mixture, the method further includes a step of mixing the geopolymer precursor material, the redispersible latex powder, and the expanding agent.

[0018] The present invention also provides the application of the aforementioned geopolymer-based aerogel fire-retardant coating or the geopolymer-based aerogel fire-retardant coating prepared according to the preparation method of the aforementioned geopolymer-based aerogel fire-retardant coating in the fire protection of steel structures.

[0019] The beneficial effects of this invention are as follows:

[0020] 1. This invention provides a geopolymer-based aerogel fire-retardant coating, comprising the following components in the following proportions: geopolymer precursor material, alkaline activator, aerogel, fiber, and water; the mass ratio of alkaline activator to geopolymer precursor material is 0.52-0.63:1; the volume content of aerogel is 70%-85%; the mass content of fiber is 0-1% and not 0; and the water-to-binder ratio is 0.5-0.7.

[0021] The geopolymer-based aerogel fire-retardant coating provided by this invention achieves multiple performance optimizations through a reasonable ratio of geopolymer precursor materials, alkaline activator, aerogel, fiber, and water: the added fiber can effectively inhibit the high-temperature shrinkage of the coating, while improving tensile strength and tensile bond strength to a certain extent, ensuring the structural stability and continuous fire resistance of the coating in fire scenarios; by optimizing the aerogel content and water-cement ratio, the coating achieves an excellent balance between thermal conductivity and compressive strength, possessing both high strength and efficient heat insulation properties; moreover, the overall production process of this invention is low-carbon and environmentally friendly, in line with the development trend of green building materials, and has both economic and environmental benefits.

[0022] 2. Under the limitations of the preparation method of the present invention, by allowing the geopolymer to react fully before the aerogel is added, the degree of reaction between the aerogel and the geopolymer can be reduced to a certain extent, thereby suppressing the negative impact of the reaction. This design not only makes the aerogel more stable in the coating system and fully exerts its heat insulation function, but also improves the mechanical property stability of the coating.

[0023] 3. The precursor materials for the geopolymer are slag and fly ash. Slag is used instead of traditional metakaolin. By accelerating the early reaction of the geopolymer and shortening the setting time of the geopolymer, the reaction between the aerogel and the alkaline solution is effectively inhibited, and the stability of the coating performance is enhanced.

[0024] 4. By introducing redispersible latex powder, an expanding agent, and basalt fiber into the coating, a multi-scale synergistic reinforcement system is formed. The redispersible latex powder improves the coating's uniformity and tensile bond strength, enhances the adhesion between the coating and the steel structure substrate, and effectively suppresses "interfacial separation" and "interlayer delamination" problems caused by insufficient adhesion between the coating and the substrate. Simultaneously, the expanding agent and basalt fiber effectively inhibit the coating's drying shrinkage and prevent shrinkage cracking. These three components work synergistically to ensure the structural integrity and durability of the coating under drying and fire conditions. Attached Figure Description

[0025] Figure 1 This is a graph showing the change in shrinkage rate of different specimens over time in Experimental Example 1 of this invention;

[0026] Figure 2This is a schematic diagram comparing the temperature of B0 at different locations in Experiment Example 4 of this invention;

[0027] Figure 3 This is a schematic diagram comparing the temperature of B20 at different locations in Experiment Example 4 of this invention;

[0028] Figure 4 This is a schematic diagram comparing the temperatures of B0 and B20 on the unexposed side in Experimental Example 4 of this invention. Detailed Implementation

[0029] This invention provides a geopolymer-based aerogel fire-retardant coating, comprising the following components in the indicated proportions:

[0030] Geopolymer precursor materials, basic activators, aerogels, fibers, and water;

[0031] The mass ratio of alkaline activator to geopolymer precursor material is 0.52-0.63:1; the volume content of aerogel is 70%-85%; the mass content of fiber is 0-1% and not zero; the water-gel ratio is 0.5-0.7.

[0032] The volumetric content of aerogel refers to the proportion of the volume of aerogel to the total volume of the polymer-based aerogel fire-retardant coating; the mass content of fiber refers to the proportion of the mass of fiber to the total mass of the polymer-based aerogel fire-retardant coating; the water-cement ratio refers to the ratio of the mass of water to the total mass of the polymer precursor material and the solute in the sodium silicate solution.

[0033] In this invention, the geopolymer precursor materials include slag and fly ash, with a mass ratio of slag to fly ash of 5-7:3-5.

[0034] In this invention, the alkaline activator includes a sodium silicate solution with a mass concentration of 38%-42% and a modulus of 1.2-1.6.

[0035] In this invention, the aerogel includes silica aerogel; the bulk density of the silica aerogel is 100 kg / m³. 3 -120kg / m 3 The specific surface area of ​​silica aerogel is 500 m². 2 / g-650m 2 / g, the porosity of silica aerogel is greater than 90%, and the pore size of silica aerogel is 20nm-100nm.

[0036] In this invention, the fiber comprises basalt fiber; the fiber length is 11mm-13mm, and the fiber diameter is... .

[0037] In this invention, the geopolymer-based aerogel fireproof coating also includes redispersible latex powder, wherein the mass content of the redispersible latex powder is 0-5% and not 0.

[0038] The mass content of redispersible latex powder refers to the proportion of the mass of redispersible latex powder to the total mass of polymer-based aerogel fireproof coating.

[0039] In this invention, the geopolymer-based aerogel fire-retardant coating also includes an expanding agent, the mass content of which is 0-6% and not 0.

[0040] The mass dosage of the expanding agent refers to the proportion of the mass of the expanding agent to the total mass of the polymer-based aerogel fireproof coating.

[0041] The present invention also provides a method for preparing the aforementioned geopolymer-based aerogel fire-retardant coating, comprising the following steps:

[0042] The geopolymer precursor material and fiber are first mixed to obtain a first mixture; the first mixture, alkaline activator and water are second mixed to obtain a second mixture; the second mixture and aerogel are third mixed to obtain a geopolymer-based aerogel fire-retardant coating.

[0043] In this invention, the rotation speed of the first mixing is 120 r / min-160 r / min, the rotation speed of the second mixing is 120 r / min-160 r / min, and the rotation speed of the third mixing is 265 r / min-305 r / min.

[0044] In this invention, before the first mixture of the geopolymer precursor material and the fiber is obtained, the method further includes a step of mixing the geopolymer precursor material, the redispersible latex powder and the expanding agent; the mixing speed is 120 r / min-160 r / min.

[0045] In this invention, the geopolymer precursor materials include slag and fly ash. When mixing slag and fly ash, the mixing speed is 120 r / min-160 r / min and the mixing time is 1.5 min-2.5 min.

[0046] The present invention also provides the application of the aforementioned geopolymer-based aerogel fire-retardant coating or the geopolymer-based aerogel fire-retardant coating prepared according to the preparation method of the aforementioned geopolymer-based aerogel fire-retardant coating in the fire protection of steel structures.

[0047] The present invention will be further described below with reference to the accompanying drawings and embodiments. Unless otherwise defined, the technical or scientific terms used in this invention should be understood in their ordinary sense by those skilled in the art. The features mentioned above or in the specific examples mentioned in this invention can be combined arbitrarily, and these specific embodiments are only used to illustrate the invention and are not intended to limit the scope of the invention.

[0048] In the following embodiments and comparative examples of this invention, the slag was purchased from Shijiazhuang Zhengyu New Material Technology Co., Ltd., and was grade S95; the fly ash was purchased from Shijiazhuang Zhengyu New Material Technology Co., Ltd., and was grade 1; the sodium silicate solution was purchased from Jiashan Yourui Refractory Materials Co., Ltd., with a mass concentration of 35.88% and a modulus of 3.3. In use, a certain amount of solid sodium hydroxide and water were added, and after stirring evenly, a sodium silicate solution with a modulus of 1.4 and a mass concentration of 40% was obtained; the silica aerogel was selected from Guangdong Ailisheng Technology Co., Ltd., with a bulk density of 110 kg / m³. 3 Specific surface area is 575m² 2 / g, porosity 92%, pore size 60nm; basalt fiber purchased from Senxiang Building Materials Store, Langli Street, Changsha County, length 12mm, diameter [missing information]. The redispersible latex powder is Wacker 5010 N latex powder produced by Shanghai Chenqi Chemical Technology Co., Ltd., and its main component is ethylene-vinyl acetate. The expansive agent was purchased from Guzhen Jingfan Concrete Admixture Manufacturer, and its main components are calcium oxide, calcium sulfate, and calcium sulfoaluminate. Its full name is high-performance concrete expansive agent, abbreviated as HCSA expansive agent.

[0049] Example 1

[0050] This embodiment provides a geopolymer-based aerogel fire-retardant coating, comprising the following components in the following proportions:

[0051] Geopolymer precursor materials (including slag and fly ash in a mass ratio of 6:4), alkaline activator (sodium silicate solution with a mass concentration of 40% and a modulus of 1.4), aerogel (silica aerogel), fiber (basalt fiber), redispersible latex powder, swelling agent, and water.

[0052] The mass ratio of alkaline activator to geopolymer precursor material is 0.57:1; the volume content of aerogel is 70%; the mass content of fiber is 1%; the mass content of redispersible latex powder is 2.5%; the mass content of swelling agent is 4%; and the water-gel ratio is 0.6.

[0053] This embodiment also provides a method for preparing a geopolymer-based aerogel fire-retardant coating, including the following steps:

[0054] Redispersible latex powder and expanding agent were added to the geopolymer precursor materials (including slag and fly ash; when mixing slag and fly ash, the mixing speed was 140 r / min and the mixing time was 2 min), and the mixture was stirred at 140 r / min until homogeneous. Then, fibers were added, and stirring was continued at the same speed. After stirring until homogeneous, an alkaline activator and water were added, and the mixture was stirred at 140 r / min. Finally, aerogel was added, and the speed was increased to 285 r / min, and the mixture was stirred until completely homogeneous to obtain a geopolymer-based aerogel fireproof coating (marked as 2.5JF-1.0XW-4.0PZJ).

[0055] Example 2

[0056] This embodiment provides a geopolymer-based aerogel fireproof coating, which is basically the same as that in Embodiment 1, except that the mass content of the expanding agent is modified to 6% (marked as 2.5JF-1.0XW-6.0PZJ).

[0057] Comparative Example 1

[0058] This comparative example provides a geopolymer-based aerogel fire-retardant coating, which is basically the same as Example 1, except that the mass content of redispersible latex powder is modified to 5%, the mass content of fiber is 0%, and the mass content of expanding agent is 0 (marked as 5.0JF).

[0059] Comparative Example 2

[0060] This comparative example provides a geopolymer-based aerogel fire-retardant coating, which is basically the same as Example 1, except that the mass content of the fiber is modified to be 0 and the mass content of the expanding agent is 0 (marked as 2.5JF).

[0061] Comparative Example 3

[0062] This comparative example provides a geopolymer-based aerogel fire-retardant coating, which is basically the same as Example 1, except that the mass content of redispersible latex powder is modified to be 0, the mass content of fiber is 0, and the mass content of expanding agent is 0 (marked as 0.70AG-0.60).

[0063] Experimental Example 1

[0064] Shrinkage deformation tests were conducted on the geopolymer-based aerogel fire-retardant coatings of Examples 1-2 and Comparative Examples 1-3. Dry shrinkage specimens were prepared according to the "Test Method for Dry Shrinkage of Cement Mortar" (JC / T603-2004). Three specimens were prepared for each type of geopolymer-based aerogel fire-retardant coating (average value was taken). A shrinkage mold with inner wall dimensions of 25mm × 25mm × 280mm and nail heads were assembled, and the geopolymer-based aerogel fire-retardant coating was poured into it. The coating was vibrated evenly with a tamping rod, and the surface was smoothed with a scraper. The mold and specimens were then placed in a standard curing chamber. After 1 day, the mold was removed, and the specimens were placed in a programmable temperature and humidity curing chamber set at 20℃ and 50% relative humidity for curing. Shrinkage deformation tests were conducted using a length comparator. The specimen length was measured at demolding and recorded as the initial length. The specimen length was measured at the same time each day thereafter, and the difference between the specimen length and the initial value was recorded as the shrinkage value. Shrinkage rate = shrinkage value / initial length. The test lasted for 28 days, and curves showing the change in shrinkage rate of different specimens over time were obtained, as shown below. Figure 1 As shown.

[0065] from Figure 1 As can be seen, basalt fiber and expanding agent can effectively inhibit the shrinkage of coatings and help to alleviate the cracking problem of coatings. Among them, the formulation containing 2.5% redispersible latex powder, 1% fiber and 4% expanding agent (Example 1) has the least shrinkage after being placed in the same environment for the same time.

[0066] Experimental Example 2

[0067] Tensile strength tests were conducted on the geopolymer-based aerogel fire-retardant coatings of Examples 1-2 and Comparative Examples 1-3. The test specimens were prepared according to the "Test Procedure for Polymer Modified Cement Mortar" (DL / T5126-2021). Three specimens were prepared for each group (average value was taken), and they were cured in a standard curing chamber for 28 days. Tensile strength tests were performed using a UTM5205 universal testing machine manufactured by Shenzhen Sansi Zongheng Technology Co., Ltd., with a loading speed of 5 mm / min. The peak force was recorded after specimen failure, and the width and thickness of the failure section were measured using vernier calipers. The tensile strength was calculated using the following formula: In the formula, f t Tensile strength is expressed in MPa; P is the failure load, the maximum tensile force applied by the testing machine at the point of specimen failure, expressed in N; S is the failure area, the projected area of ​​the failure section perpendicular to the direction of force, expressed in mm. 2 The tensile strength test results of different specimens are shown in Table 1.

[0068] Table 1 Tensile strength test results of different specimens

[0069]

[0070] As can be seen from Table 1, formulations containing redispersible latex powder, fiber, and expanding agent have higher tensile strength.

[0071] Experimental Example 3

[0072] The geopolymer-based aerogel fire-retardant coatings of Examples 1-2 and Comparative Examples 1-3 were used to prepare tensile bond specimens and test tensile bond strength according to GB14907-2018 "Fire-retardant Coatings for Steel Structures". The loading speed was set to 1500 N / min during the test. The tensile bond strength was calculated using the following formula: In the formula: f b Bond strength (MPa); F (maximum tensile load, N); A (bonded area, mm²). 2 The tensile bond strength results are expressed as the average value after removing gross errors from the five test values. The tensile bond strength test results for different specimens are shown in Table 2.

[0073] Table 2. Tensile bond strength test results of different specimens

[0074]

[0075] Tensile bond strength is an important indicator for evaluating the coating's resistance to peeling; the higher the tensile bond strength between the coating and the steel plate, the less likely it is to peel off. Tensile bond test results show that adhesive powder, basalt fiber, and expanding agent all improve the tensile bond strength between the coating and the steel plate. Among them, the 2.5JF-1.0XW-6.0PZJ group has the highest tensile bond strength, but its workability is poor. Considering all factors, 2.5JF-1.0XW-4.0PZJ is selected as the preferred formulation.

[0076] Experiment Example 4

[0077] The thermal insulation performance of the geopolymer-based aerogel fireproof coating of Example 1 was tested: Two Q235 steel plates were prepared with a length, width and thickness of 320mm, 280mm and 4mm respectively. One steel plate was not coated with fireproof coating and served as a control specimen (marked as B0). The other plate was coated with a 20mm thick fireproof coating (marked as B20) (geolithic aerogel fireproof coating of Example 1). After the coating was applied, the specimens were placed in a standard curing chamber (temperature 20℃, humidity 90%) for 7 days and then air-dried for 2 days.

[0078] The experiment simulated a steel plate coated with a fire extinguishing agent on one side. During testing, the specimen was vertically fixed in front of an open resistance furnace, with the coated side facing the furnace interior, and the outer side of the steel plate sealed with fireproof cotton. Type K armored thermocouples were used to monitor the temperature at different locations, including the fire-exposed side, the interior of the coating, the interface between the coating and the steel plate, and the unexposed side. The furnace temperature was increased to 1000℃ at a programmed rate of 8℃ / min and then held for 2 hours (1 hour for B0). Data was collected every 3 seconds. According to the standard "Fire-retardant Coatings for Steel Structures" (GB14907-2018), the insulation efficiency was evaluated by the time (t) it took for the average temperature of the unexposed side to reach 500℃.

[0079] Based on the above tests, a schematic diagram comparing the temperatures of B0 at different locations was obtained, as shown below. Figure 2 As shown; a schematic diagram comparing the temperature of B20 at different locations, as shown. Figure 3 As shown; a schematic diagram comparing the temperatures of B0 and B20 on the unexposed side, as shown. Figure 4 As shown. From Figures 2-4 It can be found that geopolymer-based aerogel fireproof coatings have good heat insulation properties.

[0080] Therefore, the present invention adopts the above-mentioned geopolymer-based aerogel fireproof coating and its preparation method. By rationally selecting components and proportions and rationally setting the preparation process, multiple performance optimizations of the fireproof coating are achieved.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A geopolymer-based aerogel fire-retardant coating, characterized in that, Includes the following components in the following proportions: Geopolymer precursor materials, alkaline activators, aerogels, fibers, redispersible latex powder, swelling agents, and water; The mass ratio of alkaline activator to geopolymer precursor material is 0.52-0.63:1; the volume content of aerogel is 70%-85%; and the mass content of fiber is 0-1% and not zero. The water-to-binder ratio is 0.5-0.7; the mass content of redispersible latex powder is 0-5% and not zero; the mass content of the expanding agent is 0-6% and not zero.

2. The geopolymer-based aerogel fire-retardant coating according to claim 1, characterized in that, Geopolymer precursor materials include slag and fly ash, with a mass ratio of slag to fly ash of 5-7:3-5.

3. The geopolymer-based aerogel fire-retardant coating according to claim 1, characterized in that, The alkaline activator includes sodium silicate solution with a mass concentration of 38%-42% and a modulus of 1.2-1.

6.

4. The geopolymer-based aerogel fire-retardant coating according to claim 1, characterized in that, Aerogels include silica aerogels; the bulk density of silica aerogels is 100 kg / m³. 3 -120kg / m 3 The specific surface area of ​​silica aerogel is 500 m². 2 / g-650m 2 / g, the porosity of silica aerogel is greater than 90%, and the pore size of silica aerogel is 20nm-100nm.

5. The geopolymer-based aerogel fire-retardant coating according to claim 1, characterized in that, The fibers include basalt fibers; the fiber length is 11mm-13mm and the fiber diameter is 16μm-18μm.

6. The method for preparing the geopolymer-based aerogel fire-retardant coating according to any one of claims 1-5, characterized in that, Includes the following steps: The geopolymer precursor material and fiber are first mixed to obtain a first mixture; the first mixture, alkaline activator and water are second mixed to obtain a second mixture; the second mixture and aerogel are third mixed to obtain a geopolymer-based aerogel fire-retardant coating.

7. The method for preparing the geopolymer-based aerogel fire-retardant coating according to claim 6, characterized in that, Before the first mixture is obtained by first mixing the geopolymer precursor material and the fiber, the process further includes the step of mixing the geopolymer precursor material, the redispersible latex powder and the expanding agent.

8. The application of the geopolymer-based aerogel fire-retardant coating according to any one of claims 1-5 or the geopolymer-based aerogel fire-retardant coating prepared by the preparation method according to claim 6 or 7 in the fire protection of steel structures.

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