A dense clay brick and a method for making the same

Abstract

The application relates to the technical field of clay bricks, and discloses a dense clay brick and a preparation method thereof. The dense clay brick comprises 100 parts by weight of soft clay, 25-40 parts by weight of red mud, 20-32 parts by weight of fly ash, 4-8 parts by weight of a sulphurous acid paper pulp waste liquid binder and 0.1-0.6 parts by weight of modified carbon fibers. The surface of the modified carbon fibers contains a large number of double quaternary ammonium salt cation structures, can have electrostatic interaction with anions on the surface of the clay, enhances the interfacial bonding performance between the carbon fibers and the clay, makes the inside of the clay brick more compact, improves the bulk density and compactness of the clay brick, is beneficial to reducing the water absorption rate and improving the water resistance and waterproof performance. Moreover, the carbon fibers have large strength, high modulus and strong compression resistance, the interfacial bonding performance between the modified carbon fibers and the clay is better, and the compression strength and the bending strength of the clay brick are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of clay bricks, in particular to a dense clay brick and a preparation method thereof. BACKGROUND

[0002] Clay bricks are man-made small block materials for building, which are made of clay as the main raw material through processes such as clay treatment, molding, drying and baking. They have the advantages of low cost, durability, fireproofing and heat insulation, and are widely used in the field of building. However, clay bricks have problems such as high water absorption rate and poor strength, which limit their practical application in high-end building manufacturing and other aspects.

[0003] Carbon fiber is a high-strength and high-modulus fiber material, and has good high-temperature resistance and fireproofing performance. It is widely used in concrete, refractory bricks, asphalt and other building materials. Chinese patent CN109942283B discloses a carbon fiber toughened hollow brick and a preparation method thereof, which uses hemp fiber, ammonium persulfate, aminopropyl triethoxysilane, carbon fiber, acrylamide, tetrabutyl titanate and epoxy propanol as raw materials to prepare carbon fiber-based polymer modified fiber, which can be used for toughening hollow bricks. However, the carbon fiber-based polymer modified fiber does not reduce the water absorption rate of the brick and does not improve the water resistance and waterproof performance. SUMMARY

[0004] The present application solves the problems of low density, high water absorption rate and poor strength of clay bricks.

[0005] The technical solution provided by the present application is as follows: a dense clay brick, characterized in that the dense clay brick comprises the following components: 100 parts by weight of soft clay, 25-40 parts by weight of red mud, 20-32 parts by weight of fly ash, 4-8 parts by weight of sulfurous acid paper pulp waste liquid binder and 0.1-0.6 parts by weight of modified carbon fiber.

[0006] Further, the preparation method of the modified carbon fiber is as follows:

[0007] (1) The chopped carbon fiber is added to concentrated nitric acid for oxidation to obtain oxidized carbon fiber, and then placed in thionyl chloride for acyl chloride treatment to obtain acyl chloride carbon fiber.

[0008] (2) The acyl chloride carbon fiber is placed in a reaction solvent, dispersed, then triethylamine and 1,3-bis-chloroethyl quaternary ammonium salt-2-propanol are added, and after reaction, the filter cake is washed with distilled water and dried to obtain the modified carbon fiber.

[0009] Further, the reaction solvent is any one of tetrahydrofuran, dichloromethane and ethyl acetate.

[0010] Further, the weight ratio of the acyl chloride carbon fiber, triethylamine and 1,3-bis(chloroethyl) quaternary ammonium salt-2-propanol in (2) is 1:(0.18-0.56):(0.3-1).

[0011] Further, the reaction control temperature in (2) is 40-65 DEG C, and the time is 24-48h.

[0012] Further, the preparation method of 1,3-bis(chloroethyl) quaternary ammonium salt-2-propanol is as follows: 1,3-bis(dimethylamino)-2-propanol and 1-chloroethane with a weight ratio of 1:(0.85-0.92) are added into acetonitrile, heated to 70-80 DEG C, and reacted for 36-48h; the solution is concentrated under reduced pressure; and the product is recrystallized in distilled water to obtain 1,3-bis(chloroethyl) quaternary ammonium salt-2-propanol.

[0013] Further, the preparation method of the dense clay brick is characterized in that the preparation method of the dense clay brick is as follows: soft clay, red mud, fly ash and modified carbon fiber are added into a sand mixer and mixed for 2-5min, then sulfurous acid paper pulp waste liquid binder is added and mixed for 3-8min; then the material is placed in a friction brick press to be impact formed into a brick blank; finally, the brick blank is heat treated at 130-160 DEG C for 12-24h, and cured at room temperature for 24-48h to obtain the dense clay brick.

[0014] The technical effect of the present application is that the acyl chloride groups on the surface of the acyl chloride carbon fiber are esterified with the hydroxyl groups of 1,3-bis(chloroethyl) quaternary ammonium salt-2-propanol, so that a large number of double quaternary ammonium salt cation structures are introduced on the surface of the modified carbon fiber; and the modified carbon fiber, soft clay, red mud, fly ash and sulfurous acid paper pulp waste liquid binder are used as raw materials to prepare the dense clay brick.

[0015] The surface of the modified carbon fiber contains a large number of double quaternary ammonium salt cation structures, which can electrostatically interact with the anions on the surface of the clay, so as to enhance the interfacial bonding performance between the carbon fiber and the clay, make the inside of the clay brick more compact, improve the bulk density and compactness of the clay brick, and be beneficial to reducing the water absorption and improving the water resistance and waterproof performance. In addition, the carbon fiber has high strength, modulus and compression resistance, the interfacial bonding performance between the modified carbon fiber and the clay is better, and the compression strength and flexural strength of the clay brick are significantly improved. DETAILED DESCRIPTION

[0016] In the following, the present application will be further described in conjunction with specific embodiments, and it should be noted that the embodiments described below or the technical features thereof can be combined in any manner to form new embodiments. The equipment and raw materials used can be purchased from the market or are commonly used in the art. The methods in the following examples are conventional methods in the art unless otherwise specified.

[0017] The short carbon fiber of the present application: average diameter 15 um, length 3 mm. NanYu Mineral Product Processing Factory in LingShou County.

[0018] Soft clay, main component is kaolin, average particle size is 1200 mesh. Zhanxing Mineral Product Co., Ltd. in LingShou County.

[0019] Red mud is an industrial solid waste generated by industrial production of alumina; Wujiang Yongsheng Chemical Co., Ltd.

[0020] Fly ash, average particle size 325 mm; Shengyun Mineral Product Processing Factory in LingShou County.

[0021] Sulfurous acid paper pulp waste liquid binder, component is waste liquid generated by paper pulp. Guangxi Senbaoyuan Agricultural Co., Ltd.

[0022] Example 1

[0023] (1) 0.5 g of short carbon fiber was added to 15 mL of 70% concentrated nitric acid, heated to 100℃, oxidized for 2 h, washed with distilled water after filtration, and dried to obtain oxidized carbon fiber; then the oxidized carbon fiber was placed in 10 mL of thionyl chloride, and acyl chloride was carried out at 40℃ for 8 h, filtered, washed with acetone, and dried to obtain acyl chloride carbon fiber.

[0024] (2) 0.2 g of 1,3-bis(dimethylamino)-2-propanol and 0.176 g of 1-chloroethane were added to 3 mL of acetonitrile in a weight ratio, heated to 80℃, and reacted for 36 h. The solution was concentrated under reduced pressure, and the product was recrystallized in distilled water to obtain 1,3-bis(chloroethyl) quaternary ammonium salt-2-propanol. The reaction formula is as follows:

[0025]

[0026] (3) 0.5 g of acyl chloride carbon fiber was placed in 20 mL of ethyl acetate reaction solvent, dispersed, and then 0.09 g of triethylamine and 0.15 g of 1,3-bis(chloroethyl) quaternary ammonium salt-2-propanol were added. It was heated to 40℃ and reacted for 48 h. After the reaction, suction filtration was carried out, the filter cake was washed with distilled water, and dried to obtain modified carbon fiber.

[0027] (4) 10 kg of soft clay, 3.6 kg of red mud, 2 kg of fly ash, and 10 g of modified carbon fiber were added to a sand mixer and mixed for 5 min, then 0.4 kg of sulfurous acid paper pulp waste liquid binder was added and mixed for 3 min; then the material was placed in a friction brick press and impact formed into a green brick; finally, the green brick was heat treated at 130℃ for 24 h and cured at room temperature for 24 h to obtain a dense clay brick.

[0028] Example 2

[0029] (1) Add 0.2 g of 1,3-bis(dimethylamino)-2-propanol and 0.184 g of 1-chloroethane to 3 mL of acetonitrile, heat to 70 °C, react for 48 h, concentrate the solution under reduced pressure, and recrystallize the product in distilled water to obtain 1,3-bischloroethyl quaternary ammonium salt-2-propanol.

[0030] (2) 0.5g of acyl chloride carbon fiber (prepared in the same way as in Example 1) was placed in 20mL of tetrahydrofuran reaction solvent, dispersed, and then 0.14g of triethylamine and 0.28g of 1,3-dichloroethyl quaternary ammonium salt-2-propanol were added. The mixture was heated to 65℃ and reacted for 24h. After the reaction, the mixture was filtered, the filter cake was washed with distilled water and dried to obtain modified carbon fiber.

[0031] (3) Add 10kg of soft clay, 2.5kg of red mud, 2.8kg of fly ash and 25g of modified carbon fiber to a sand mixer and mix for 2 minutes. Then add 0.4kg of sulfite pulp waste liquid binder and mix for 8 minutes. Next, place the material in a friction brick press and press it to form a brick blank. Finally, heat treat the brick blank at 160℃ for 12 hours and cure it at room temperature for 48 hours to obtain dense clay bricks.

[0032] Example 3

[0033] (1) Add 0.2 g of 1,3-bis(dimethylamino)-2-propanol and 0.17 g of 1-chloroethane to 3 mL of acetonitrile, heat to 80 °C, react for 36 h, concentrate the solution under reduced pressure, and recrystallize the product in distilled water to obtain 1,3-bischloroethyl quaternary ammonium salt-2-propanol.

[0034] (2) 0.5g of acyl chloride carbon fiber (prepared in the same way as in Example 1) was placed in 30mL of dichloromethane reaction solvent, dispersed, and then 0.19g of triethylamine and 0.4g of 1,3-dichloroethyl quaternary ammonium salt-2-propanol were added. The mixture was heated to 65℃ and reacted for 36h. After the reaction, the mixture was filtered, the filter cake was washed with distilled water and dried to obtain modified carbon fiber.

[0035] (3) Add 10kg of soft clay, 2.5kg of red mud, 3.2kg of fly ash and 45g of modified carbon fiber to a sand mixer and mix for 5min. Then add 0.7kg of sulfite pulp waste liquid binder and mix for 5min. Next, place the material in a friction brick press and press it to form a brick blank. Finally, heat treat the brick blank at 160℃ for 12h and cure it at room temperature for 48h to obtain dense clay brick.

[0036] Example 4

[0037] (1) Add 0.2 g of 1,3-bis(dimethylamino)-2-propanol and 0.17 g of 1-chloroethane to 2 mL of acetonitrile, heat to 75 °C, react for 48 h, concentrate the solution under reduced pressure, and recrystallize the product in distilled water to obtain 1,3-bischloroethyl quaternary ammonium salt-2-propanol.

[0038] (2) 0.5g of acyl chloride carbon fiber (prepared in the same way as in Example 1) was placed in 30mL of ethyl acetate reaction solvent, dispersed, and then 0.23g of triethylamine and 0.5g of 1,3-dichloroethyl quaternary ammonium salt-2-propanol were added. The mixture was heated to 50℃ and reacted for 48h. After the reaction, the mixture was filtered, the filter cake was washed with distilled water and dried to obtain modified carbon fiber.

[0039] (3) Add 10kg of soft clay, 4kg of red mud, 2.5kg of fly ash and 60g of modified carbon fiber to a sand mixer and mix for 5min. Then add 0.8kg of sulfite pulp waste liquid binder and mix for 6min. Next, place the material in a friction brick press and press it to form a brick blank. Finally, heat treat the brick blank at 130℃ for 24h and cure it at room temperature for 48h to obtain dense clay brick.

[0040] Comparative Example 1

[0041] The difference between Comparative Example 1 and Example 1 is that no modified carbon fiber is added to the dense clay bricks.

[0042] 10 kg of soft clay, 3.6 kg of red mud, and 2 kg of fly ash were added to a sand mixer and mixed for 5 minutes. Then, 0.4 kg of sulfite pulp waste liquid binder was added and mixed for 3 minutes. The material was then placed in a friction brick press and shaped into brick blanks. Finally, the brick blanks were heat-treated at 130℃ for 24 hours and cured at room temperature for 24 hours to obtain dense clay bricks.

[0043] Comparative Example 2

[0044] The difference between Comparative Example 2 and Example 1 is that no modified carbon fiber was added to the dense clay bricks, but unmodified carbon fiber was added.

[0045] 10 kg of soft clay, 3.6 kg of red mud, 2 kg of fly ash, and 10 g of carbon fiber were added to a sand mixer and mixed for 5 minutes. Then, 0.4 kg of sulfite pulp waste liquor binder was added and mixed for 3 minutes. The material was then placed in a friction brick press and shaped into brick blanks. Finally, the brick blanks were heat-treated at 130℃ for 24 hours and cured at room temperature for 24 hours to obtain dense clay bricks.

[0046] Performance testing:

[0047] The compressive strength was determined according to GB / T 5072-2008. The flexural strength was tested according to GB / T 3001-2017. The bulk density of the clay bricks was tested according to GB / T 2997-2015.

[0048] Water absorption rate test of clay bricks: Prepare clay brick samples of 20cm × 10cm × 4cm, weigh them, and soak them in distilled water for 48 hours. Remove the clay bricks, wipe off excess water from the surface, and weigh them again. Calculate the water absorption rate. Water absorption rate W = (m - m0) / m0 × 100%. m is the mass of the clay brick after water absorption, and m0 is the mass of the clay brick before water absorption.

[0049] The performance test results of the dense clay brick products of the above embodiments and comparative examples are shown in Table 1.

[0050] Table 1 Performance Tests of Clay Bricks

[0051]

[0052]

[0053] As shown in Table 1, the clay bricks prepared in Examples 1-4 have a compressive strength of 13.6-24.5 MPa, a flexural strength of 4.5-7.9 MPa, and a bulk density of 1.53-1.94 g / cm³. 3 The water absorption rate is only 18.6-24.5%. It possesses advantages such as high strength, high bulk density, strong compactness, and good water resistance. This is because the modified carbon fiber surface contains a large number of bis-quaternary ammonium salt cation structures, which can electrostatically interact with the anions on the clay surface, enhancing the interfacial bonding performance between the carbon fiber and the clay. This makes the clay bricks more compact, thereby increasing their bulk density and compactness, which helps reduce water absorption and improve water resistance. Furthermore, the carbon fiber has high strength, high modulus, and strong compressive strength. The modified carbon fiber has better interfacial bonding performance with the clay, significantly improving the compressive and flexural strength of the clay bricks.

[0054] The clay bricks in Comparative Example 1 did not contain modified carbon fiber, resulting in lower density and compactness, higher water absorption, and poor water resistance. Furthermore, their compressive and flexural strengths were also lower.

[0055] Comparative Example 2 only added unmodified carbon fibers, whose surface does not contain a bis-quaternary ammonium salt cationic structure. Therefore, it cannot electrostatically interact with the anions on the clay surface, resulting in low interfacial bonding performance with the clay. This did not improve the internal compactness of the clay bricks, leading to high water absorption and poor water resistance. Furthermore, its compressive strength and flexural strength were lower than those of Examples 1-4.

[0056] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A dense clay brick, characterized in that, The dense clay brick is composed of the following components: 100 parts by weight of soft clay, 25-40 parts by weight of red mud, 20-32 parts by weight of fly ash, 4-8 parts by weight of sulfite pulp waste liquor binder, and 0.1-0.6 parts by weight of modified carbon fiber. The method for preparing the modified carbon fiber is as follows: (1) Short carbon fibers are added to concentrated nitric acid for oxidation to obtain oxidized carbon fibers, and then placed in thionyl chloride for acyl chloride to obtain acyl chloride carbon fibers; (2) The acyl chloride carbon fiber is placed in the reaction solvent, dispersed, and then triethylamine and 1,3-dichloroethyl quaternary ammonium salt-2-propanol are added. After the reaction, the mixture is filtered, washed, and dried to obtain modified carbon fiber. The weight ratio of acyl chloride carbon fiber, triethylamine, and 1,3-dichloroethyl quaternary ammonium salt-2-propanol is 1:(0.18-0.56):(0.3-1). The preparation method of the 1,3-dichloroethyl quaternary ammonium salt-2-propanol is as follows: 1,3-bis(dimethylamino)-2-propanol and 1-chloroethane are added to acetonitrile, heated to 70-80℃, and reacted for 36-48h. The solution is concentrated under reduced pressure, and the product is recrystallized in distilled water to obtain 1,3-dichloroethyl quaternary ammonium salt-2-propanol, wherein the weight ratio of 1,3-bis(dimethylamino)-2-propanol and 1-chloroethane is 1:(0.85-0.92).

2. The dense clay brick according to claim 1, characterized in that, The reaction solvent in (2) is any one of tetrahydrofuran, dichloromethane, or ethyl acetate.

3. The dense clay brick according to claim 1, characterized in that, The reaction temperature in (2) is controlled at 40-65℃ and the reaction time is 24-48h.

4. A method for preparing dense clay bricks as described in any one of claims 1-3, characterized in that, The preparation method of the dense clay brick is as follows: soft clay, red mud, fly ash and modified carbon fiber are added to a sand mixer and mixed for 2-5 minutes, then sulfite pulp waste liquid binder is added and mixed for 3-8 minutes; then the material is placed in a friction brick press and shaped into a brick blank; finally, the brick blank is heat-treated and cured to obtain a dense clay brick.

5. The method for preparing dense clay bricks according to claim 4, characterized in that, The heat treatment temperature is 130-160℃, and the time is 12-24h.

6. The method for preparing dense clay bricks according to claim 4, characterized in that, The curing process is carried out at room temperature for 24-48 hours.

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