Porous hollow ceramsite as well as preparation method and application thereof and light fire-resistant heat-insulating concrete slab

Abstract

The invention discloses a porous hollow ceramsite, a preparation method and application thereof and a light fire-resistant heat-insulation concrete slab, and relates to the technical field of fire-resistant heat-insulation materials, and the preparation method of the porous hollow ceramsite comprises the following steps: uniformly mixing sludge, clay, activated carbon, aluminum oxide and urea, making into spheres, and calcining at high temperature to obtain the porous hollow ceramsite; the porous hollow ceramsite is applied to the preparation of the light fire-resistant heat-insulating concrete plate. According to the invention, the porous hollow ceramsite is used as a raw material, and due to water absorption, moisture in the porous hollow ceramsite is gradually diffused in the curing process, so that internal curing is realized, and the curing difficulty of the concrete slab is reduced; and through cooperation of the porous hollow ceramsite and the low-melting-point inorganic powder, the prepared lightweight concrete slab does not crack at a high temperature under the condition that the lightweight concrete slab is thin, and the heat insulation effect is good.

Description

Technical Field

[0001] The invention relates to the technical field of fireproof and heat-insulating materials, and in particular to porous hollow ceramsite, a preparation method and application thereof, and a lightweight fire-resistant and heat-insulating concrete board. Background Art

[0002] Fires have high temperatures (up to 1000°C or above), fast heating rates (with thermal shock), and long durations. Fires not only cause heavy casualties and equipment damage, but also cause permanent damage to the strength of building materials or steel structures, such as high-temperature concrete cracking, peeling of protective layers, and reduced concrete durability. At present, some structural measures or preventive measures are usually taken to reduce the probability of concrete fires, such as spraying fire-retardant coatings on the outside of concrete components. When a fire occurs, the fire-retardant coating can significantly prevent the transfer of flames and heat in the concrete, reduce its transfer rate, and thus improve its fire resistance to achieve a protective effect.

[0003] However, this fire prevention measure only relies on "external forces" for passive fire prevention, and does not fully utilize the fire protection capabilities of the concrete structure itself. In addition, the fire-retardant coating is prone to fall off or fail, and needs to be updated during the entire life cycle of the concrete, increasing maintenance costs.

[0004] In addition, since many casualties in fires are caused by thick smoke, according to the requirements of GB / T51251-2017 Technical Standard for Smoke and Exhaust Systems in Buildings, smoke exhaust channels need to be set up. However, existing smoke exhaust channels, such as metal materials, are heat-conducting, easy to soften and corrode at high temperatures, so a lightweight, heat-insulating, and high-temperature resistant material is needed for fire protection and heat insulation. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a porous hollow ceramsite and a preparation method thereof, and apply the obtained porous hollow ceramsite to the preparation of a lightweight fire-resistant and heat-insulating concrete board.

[0006] The technical problem to be solved by the present invention is achieved by adopting the following technical solutions:

[0007] The first object of the present invention is to provide a method for preparing porous hollow ceramsite, wherein sludge, clay, activated carbon, alumina and urea are uniformly mixed to form a sphere, and then calcined at high temperature to obtain porous hollow ceramsite.

[0008] The second object of the present invention is to provide a porous hollow ceramsite obtained by the preparation method of the porous hollow ceramsite.

[0009] The third object of the present invention is to provide the use of the porous hollow ceramsite as a lightweight fire-resistant heat-insulating material.

[0010] The fourth object of the present invention is to provide the use of the porous hollow ceramsite in preparing a lightweight fire-resistant and heat-insulating concrete board.

[0011] A fifth object of the present invention is to provide a lightweight fire-resistant and heat-insulating concrete board, comprising cement, porous hollow ceramsite and low-melting-point inorganic powder.

[0012] The sixth object of the present invention is to provide a method for preparing the lightweight fire-resistant and heat-insulating concrete board, wherein all raw materials are mixed with water and evenly pressed into a body, and the body is cured and matured to obtain lightweight fire-resistant and heat-insulating concrete.

[0013] A seventh object of the present invention is to provide use of the lightweight fire-resistant and heat-insulating concrete board in flues, fire walls, and fire doors.

[0014] The beneficial effects of the present invention are:

[0015] 1. Conventional ceramsite is a particle with dense surface, low water absorption rate and density, and is not easy to disperse evenly during use; however, the porous hollow ceramsite of the present invention has a larger specific gravity after absorbing water, which is conducive to its uniform dispersion in concrete and gives full play to its effect.

[0016] 2. Since the concrete slab is relatively thin, moisture is easily volatilized, making maintenance difficult and causing cracking of the concrete slab. The present invention uses porous hollow ceramsite as raw material. Since the porous hollow ceramsite has water absorption, moisture in the porous hollow ceramsite gradually diffuses during the maintenance process, thus achieving internal maintenance and reducing the difficulty of maintaining the concrete slab.

[0017] 3. The lightweight concrete slab prepared by the present invention through the combination of porous hollow ceramsite and low melting point inorganic powder does not crack at high temperature when it is relatively thin, and has good heat insulation effect, which meets the requirements of GB / T9978.1-2009. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A photo of the porous hollow ceramsite prepared in Example 1;

[0019] Figure 2 The cross-sectional electron micrograph of the porous hollow ceramsite prepared in Example 1;

[0020] Figure 3 This is a photo of the concrete slab prepared in Example 6 after the fire resistance test;

[0021] Figure 4 This is a photograph of the concrete slab prepared in Comparative Example 14 after the fire resistance test. DETAILED DESCRIPTION

[0022] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below in conjunction with specific embodiments and diagrams.

[0023] The invention provides a method for preparing porous hollow ceramsite. The method comprises the following steps: uniformly mixing sludge, clay, activated carbon, alumina and urea, forming the mixture into spheres, and calcining the mixture at high temperature to obtain porous hollow ceramsite.

[0024] In a further technical solution, the specific process of the mixing includes: first dissolving urea in water, then adding activated carbon and mixing evenly, drying, and then adding sludge, clay and alumina and mixing evenly. In the present invention, the purpose of mixing and drying the urea aqueous solution with activated carbon first is to allow urea to be adsorbed on the surface of the activated carbon, and the urea decomposes at high temperature to expand the ceramsite, forming open pores inside and on the surface of the ceramsite.

[0025] In a further technical solution, the spherical shape can be achieved by a molding machine. The activated carbon and alumina in the present invention are powders.

[0026] In a further technical solution, the clay includes but is not limited to one or more of bentonite, illite, kaolin, and montmorillonite. In the present invention, the clay acts as a binder, which can bind the sludge, activated carbon, and alumina together to form a stable sphere.

[0027] In a further technical solution, the weight ratio of the sludge, clay, activated carbon, alumina and urea is (65-85):(5-20):(4-10):(2-4):(1-2).

[0028] In a further technical solution, the sludge is sludge from a sewage treatment plant. Using the sludge as a raw material not only realizes the resource utilization of the sludge, but also reduces the preparation cost of the porous hollow ceramsite.

[0029] In a further technical solution, the calcination temperature of the high-temperature calcination is 900-1100° C., and the calcination time is 0.5-2 hours.

[0030] The present invention provides a porous hollow ceramsite obtained by the above-mentioned preparation method. In some specific embodiments, the density of the porous hollow ceramsite is 100-300 kg / m 3 The water absorption rate is 20-50%, and the particle size is 3-10mm.

[0031] The present invention provides the use of the porous hollow ceramsite as a lightweight fire-resistant heat-insulating material. The porous hollow ceramsite is applied to the preparation of lightweight fire-resistant heat-insulating materials, including fire-resistant coatings, fire-resistant panels, fire-resistant blocking materials, and the like.

[0032] The invention provides use of the porous hollow ceramsite in preparing a lightweight fire-resistant heat-insulating concrete board.

[0033] The invention provides a light fire-resistant heat-insulating concrete board, which comprises cement, porous hollow ceramsite and low-melting-point inorganic powder.

[0034] In a further technical solution, the weight ratio of the cement, the porous hollow ceramsite and the low-melting-point inorganic powder is (15-30):(20-40):(5-10).

[0035] In a further technical solution, the porous hollow ceramsite is compounded by porous hollow ceramsite of various particle sizes. Through the combination of various particle sizes, the lightweight fire-resistant heat-insulating concrete board has a better heat-insulating effect.

[0036] In a further technical solution, the low melting point inorganic powder is selected from at least one of low melting point glass powder, sodium feldspar powder and potassium feldspar powder, but is not limited thereto. The low melting point inorganic powder can fuse the porous hollow ceramsite with concrete at high temperature to prevent cracks in the concrete slab at high temperature.

[0037] In a further technical solution, the lightweight fire-resistant insulating concrete also includes fillers and admixtures.

[0038] In the present invention, the filler may be a concrete filler known to those skilled in the art, including an inorganic filler and an organic filler. Specifically, the filler is selected from at least one of vermiculite, mica, hollow alumina, sand, fly ash, slag, silica fume, gypsum, and fiber. Among them, the fiber may be glass fiber, carbon fiber, steel fiber, polypropylene fiber, nylon fiber, etc. The admixture may be a concrete admixture known to those skilled in the art. Specifically, the admixture is selected from at least one of a water reducer, an early strength agent, an air entraining agent, and a thickener.

[0039] The present invention provides a method for preparing the lightweight fire-resistant heat-insulating concrete board, which comprises adding water to all raw materials, mixing them evenly, and pressing them into an embryo body, and curing and maturing the embryo body to obtain the lightweight fire-resistant heat-insulating concrete.

[0040] In a further technical solution, the curing conditions are a temperature of 20-30°C, a humidity of 70-90%, and a time of 5-7 days; the aging conditions are a temperature of 50-60°C and a time of 3-5 days.

[0041] In some specific embodiments, the density of the lightweight fire-resistant insulating concrete is 0.5-1.1 g / cm 3 .

[0042] The present invention provides use of the lightweight fire-resistant heat-insulating concrete board in flues, fire walls, fire doors and the like.

[0043] The raw materials in the following examples and comparative examples are described:

[0044] Activated carbon was purchased from Jiangsu Pushida Environmental Protection Technology Co., Ltd. with a particle size of 200 mesh;

[0045] The sludge comes from Huaiyuan County Guozhen Wastewater Treatment Co., Ltd., with a water content of 7%;

[0046] Clay was purchased from Shanxi Jufeng Kaolin Co., Ltd. with a particle size of 300 mesh;

[0047] Alumina was sourced from Anhui Yishitong Materials Technology Co., Ltd., with a particle size of 200 μm;

[0048] Cement was purchased from Conch Cement Group, model P·O 32.5;

[0049] Low melting point glass powder A was purchased from Foshan Jinggu Material Technology Co., Ltd., with a melting point of 710°C and a particle size of 300 mesh;

[0050] Low melting point glass powder B was purchased from Foshan Jinggu Material Technology Co., Ltd., with a melting point of 600°C and a particle size of 300 mesh;

[0051] High melting point glass powder was purchased from Foshan Jinggu Material Technology Co., Ltd., with a melting point of 1100°C and a particle size of 300 mesh;

[0052] Feldspar powder was purchased from Henan Fengkai Refractory Material Co., Ltd. Potassium feldspar powder and sodium feldspar powder, with a particle size of 200 mesh;

[0053] Nepheline powder was purchased from Anyang County Kailong Mining Co., Ltd., with a particle size of 200 mesh;

[0054] Solid ceramsite was purchased from Anhui Changjiuqu Environmental Protection Technology Co., Ltd. with a particle size of 3-5 mm and a density of 600 kg / m 3 , the water absorption rate is 8%.

[0055] The performance test method of porous hollow ceramsite is as follows:

[0056] Density test is in accordance with GB / T 6286-2021;

[0057] The test of water absorption is in accordance with GB / T 6287-2021.

[0058] The performance test method of concrete slab is as follows:

[0059] The test of density and flexural strength refers to the standard GB / T 7019-2014;

[0060] The test of fire protection level refers to the standard GB 8624-2012;

[0061] The fire resistance test and the back temperature rise test refer to the standard GB / T 9978.1-2008. The temperature is raised to 1400℃ in a muffle furnace, the back temperature of the concrete slab is recorded, and it is observed whether the concrete slab cracks during the heating process.

[0062] Example 1

[0063] Preparation of porous hollow ceramsite: by weight, dissolve 1 part of urea in 1 part of water, add 10 parts of activated carbon and mix evenly, dry at 80°C for 1 hour, then add 65 parts of sludge, 20 parts of clay and 4 parts of alumina and mix evenly to make a ball, calcine at 900°C for 2 hours to obtain porous hollow ceramsite.

[0064] Figure 1 A photo of the porous hollow ceramsite prepared in Example 1; Figure 2 The cross-sectional electron micrograph of the porous hollow ceramsite prepared in Example 1. Figure 1 and Figure 2 It can be seen that the ceramsite prepared in Example 1 is indeed a porous hollow structure.

[0065] Examples 2 to 3 and Comparative Examples 1 to 7

[0066] The method of Example 1 was followed, except that the amounts of sludge, clay, activated carbon, alumina and urea were adjusted, as shown in Table 1.

[0067] Table 1

[0068]

[0069] As can be seen from Table 1, the dosage of sludge, clay, activated carbon, alumina and urea needs to be controlled within a certain range in order to obtain porous hollow ceramsite with appropriate density and water absorption.

[0070] Examples 4-5 and Comparative Examples 8-9

[0071] The method of Example 1 was followed, except that the calcination temperature and calcination time were adjusted, as shown in Table 2.

[0072] Table 2

[0073] Calcination temperature (℃) Calcination time (h) <![CDATA[Density (kg / m 3 )]]> Water absorption (%) Particle size (mm) Example 1 900 2 281 30 3～5 Example 4 1100 0.5 262 35 3～5 Example 5 1000 1 276 32 3～5 Comparative Example 8 800 2 315 27 3～5 Comparative Example 9 1200 1 259 14 3～5

[0074] It can be seen from Table 2 that when the calcination temperature is lower than 900℃, the density of the porous hollow ceramsite increases and the water absorption rate decreases; when the calcination temperature is higher than 1100℃, the porous hollow ceramsite not only decreases in density but also in water absorption rate. Therefore, the porous hollow ceramsite with appropriate density and water absorption rate can be obtained only when the calcination temperature is 900-1100℃.

[0075] Comparative Example 10

[0076] The method of Example 1 is followed, except that urea is dissolved in water and then mixed with sludge, clay, activated carbon and alumina, as follows:

[0077] Dissolve 1 part of urea in 1 part of water, and then mix evenly with 65 parts of sludge, 20 parts of clay, 10 parts of activated carbon and 4 parts of alumina to make a ball. Calcined at 900°C for 2 hours to obtain porous hollow ceramsite.

[0078] Comparative Example 11

[0079] The method of Example 1 is followed, except that the sludge, clay, activated carbon, alumina and urea are directly mixed, as follows:

[0080] 65 parts of sludge, 20 parts of clay, 10 parts of activated carbon, 4 parts of alumina and 1 part of urea are mixed evenly to form a ball, which is calcined at 900°C for 2 hours to obtain porous hollow ceramsite.

[0081] Table 3

[0082]

[0083]

[0084] As can be seen from Table 3, the mixing method of "first dissolving urea in water, then adding activated carbon and mixing evenly, drying, and then adding sludge, clay and alumina and mixing evenly" adopted in Example 1 is beneficial to reducing the density of porous hollow ceramsite, improving the water absorption rate of porous hollow ceramsite, and ensuring the intact structure of porous hollow ceramsite.

[0085] Example 6

[0086] Preparation of concrete: By weight, 30 parts of cement, 30 parts of porous hollow ceramsite prepared in Example 1, 10 parts of potassium feldspar and 30 parts of water were mixed evenly and pressed into an embryo body, which was cured at a temperature of 20° C. and a humidity of 90% for 7 days, and then transferred to a 60° C. oven for aging for 3 days to obtain a concrete slab with a thickness of 1.5 cm.

[0087] Examples 7-8 and Comparative Examples 12-13

[0088] The method of Example 6 was followed, except that the amounts of cement, porous hollow ceramsite, albite and water were adjusted, as shown in Table 4.

[0089] Table 4

[0090]

[0091]

[0092] As can be seen from Table 4, the ratio of cement, porous hollow ceramsite, sodium feldspar and water needs to be controlled within a certain range to obtain a lightweight, fire-resistant and heat-insulating concrete slab. If the amount of cement is too little, the concrete slab is easy to break; if the amount of cement is too much, the concrete slab is easy to crack and the heat insulation effect is poor.

[0093] Comparative Example 14

[0094] The method of Example 6 is followed, except that the porous hollow ceramsite prepared in Example 1 is replaced by solid ceramsite, as shown in Table 5 for details.

[0095] Table 5

[0096]

[0097] It can be seen from Table 5 that the density of the concrete slab prepared with solid ceramsite increases, the fire rating decreases, the thermal insulation effect is poor, the fire resistance limit decreases, and cracking occurs ( Figure 4 ).

[0098] Examples 9-10 and Comparative Examples 15-16

[0099] The method of Example 6 is followed, except that different types of low melting point inorganic powders are added, or high melting point inorganic powders are added, or no low melting point inorganic powder is added, as shown in Table 6 for details.

[0100] Table 6

[0101]

[0102]

[0103] It can be seen from Table 6 that when high melting point glass powder is used or low melting point glass powder is not added, the fire resistance level of the prepared concrete slab is reduced, the fire resistance limit is reduced, and cracking occurs.

[0104] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing porous hollow ceramsite, characterized in that: The sludge, clay, activated carbon, alumina and urea are mixed evenly and made into balls, which are then calcined at high temperature to obtain porous hollow ceramsite.

2. The preparation method according to claim 1, characterized in that: The specific process of the mixing includes: first dissolving urea in water, then adding activated carbon and mixing evenly, drying, and then adding sludge, clay and alumina and mixing evenly; Preferably, the clay is one or more of bentonite, illite, kaolin and montmorillonite; Preferably, the weight ratio of the sludge, clay, activated carbon, alumina and urea is (65-85):(5-20):(4-10):(2-4):(1-2); Preferably, the sludge originates from a sewage treatment plant; Preferably, the calcination temperature of the high-temperature calcination is 900-1100° C., and the calcination time is 0.5-2 h.

3. The porous hollow ceramsite prepared by the preparation method according to claim 1 or 2.

4. The porous hollow ceramsite according to claim 3, characterized in that: The density of the porous hollow ceramsite is 100-300 kg / m 3 The water absorption rate is 20-50%, and the particle size is 3-10mm.

5. Use of the porous hollow ceramsite according to claim 3 or 4 as a lightweight refractory heat-insulating material.

6. Use of the porous hollow ceramsite according to claim 3 or 4 in preparing a lightweight fire-resistant and heat-insulating concrete board.

7. A lightweight fire-resistant and heat-insulating concrete board comprising cement, the porous hollow ceramsite according to claim 3 or 4, and a low-melting-point inorganic powder.

8. The lightweight fire-resistant heat-insulating concrete board according to claim 7, characterized in that: The weight ratio of the cement, the porous hollow ceramsite and the low melting point inorganic powder is (15-30):(20-40):(5-10); Preferably, the porous hollow ceramsite is compounded from porous hollow ceramsite of various particle sizes; Preferably, the low melting point inorganic powder is one or more of low melting point glass powder, sodium feldspar powder and potassium feldspar powder; Preferably, the lightweight fire-resistant and heat-insulating concrete further comprises fillers and admixtures.

9. The method for preparing the lightweight fire-resistant and heat-insulating concrete board according to claim 7 or 8, characterized in that: All raw materials are mixed with water and evenly pressed into a body, and the body is cured and matured to obtain a lightweight fire-resistant and heat-insulating concrete; Preferably, the curing conditions are a temperature of 20 to 30°C, a humidity of 70 to 90%, and a time of 5 to 7 days; Preferably, the aging conditions are a temperature of 50 to 60° C. and a time of 3 to 5 days; Preferably, the density of the lightweight fire-resistant insulating concrete is 0.5-1.1 g / cm 3 .

10. Use of the lightweight fire-resistant heat-insulating concrete board according to claim 7 or 8 or the lightweight fire-resistant heat-insulating concrete board prepared by the preparation method according to claim 9 in flues, fire walls and fire doors.

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