Preparation method of regenerated glass fiber cement-based composite material

Abstract

The invention discloses a preparation method of a regenerated glass fiber cement-based composite material. The method comprises the following steps: preparing regenerated glass fibers, specifically comprising the following steps: mechanically crushing a waste glass fiber reinforced plastic composite material to obtain a glass fiber composite material matrix, and pyrolyzing to obtain regenerated fiber agglomerates; screening and shearing the regenerated fiber mass to obtain regenerated fibers; carrying out drying pretreatment on the regenerated fibers, and then carrying out heat treatment at 550-650 DEG C to obtain regenerated glass fibers; the regenerated glass fiber cement-based composite material is prepared from the following components in 2000 parts by weight: 450-550 parts of cement, 1200-1400 parts of fine aggregate, 9-36 parts of regenerated glass fiber, 8-12 parts of a water reducing agent and 180-200 parts of water. The mechanical property and durability of the composite material can be improved, and the waste fan blade can be effectively recycled.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, in particular to a preparation method of a recycled glass fiber cement-based composite material. BACKGROUND

[0002] The solid waste such as glass steel generated by the fan blade has problems such as large output, complex composition and great impact on the environment. According to incomplete statistics, about 5700 tons of blade retired in 2018, 1.0-1.5 million tons of blade retired in 2021, and by 2040, the blade offline volume is expected to exceed 5 million tons. Therefore, how to effectively treat and dispose of glass steel and other solid waste needs to be solved.

[0003] The existing treatment methods mainly include physical recycling method, energy recycling method and chemical recycling method. Among them, the physical recycling method has relatively low cost and large treatment capacity, but it needs high-technology cutting equipment for high-strength and high-toughness waste fiber composite materials during treatment; the energy recycling method is simple to operate, but it will produce toxic gas and smoke pollution, and the combustion products will also cause secondary pollution to the environment; and the chemical recycling method has many advantages such as multiple recycling types and no secondary pollution in the decomposition process, which can protect the environment.

[0004] For example, in the prior art, the waste fan blade is processed into a uniform size strip-shaped aggregate to replace the coarse aggregate with a mass fraction of 5% and 10% in concrete, but this technical solution has the following technical problems: First, the uniform size strip-shaped aggregate has high requirements for cutting equipment, and the recycling efficiency is not high; Second, although the toughness of the concrete is improved, the waste fan blade has no significant effect on the compressive, tensile and bending strength of the concrete. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a preparation method of a recycled glass fiber cement-based composite material, which can not only improve the mechanical properties and durability of the composite material, but also realize effective recycling and utilization of waste fan blades.

[0006] To achieve the above purpose, the present application designs a preparation method of a recycled glass fiber cement-based composite material, which is characterized by comprising the following steps: S1) preparing recycled glass fibers, specifically comprising the following steps, S11) mechanically crushing the waste glass steel composite material to obtain a glass fiber composite material matrix, and pyrolyzing to obtain a recycled fiber group; S12) screening and shearing the recycled fiber group to obtain recycled fibers; S13) drying the regenerated fiber and then performing a heat treatment at 550-650° C. to obtain regenerated glass fiber; S2) preparing a recycled glass fiber cement-based composite material, wherein the recycled glass fiber cement-based composite material comprises 450-550 parts of cement, 1200-1400 parts of fine aggregate, 9-36 parts of recycled glass fiber, 8-12 parts of water reducer, and 180-200 parts of water based on 2000 parts by weight.

[0007] Furthermore, in S13), the regenerated fiber is dried in an oven for pretreatment, and heat-treated at 550-650° C. in a single-temperature-zone tubular furnace.

[0008] Furthermore, in S2), the cement is Portland cement.

[0009] Furthermore, in S2), the fine aggregate is one or more of natural sand, artificial sand or industrial ash.

[0010] Furthermore, in S2), the apparent density of the fine aggregate is 2600-2650 kg / m 3 , particle size is 0.35~0.5mm.

[0011] Furthermore, the method further includes step S3), wherein the performance of the recycled glass fiber cement-based composite material is tested, and the recycled glass fiber cement-based composite material is prepared into a composite material specimen. The preparation of the composite material specimen specifically includes the following steps: S31) adding sand, cement, and the regenerated glass fiber prepared in step S1) into a mixer, stirring for a period of time, then adding water and a water reducing agent, and continuing to stir; S32) Pour the mixed mortar into the mold, vibrate and smooth the surface, and remove the mold after leaving it indoors for a period of time; S33) The composite material specimen after demoulding is cured to the age, and then taken out for relevant testing.

[0012] Furthermore, in S31), before adding water and the water reducing agent, stirring is performed for 25 to 45 seconds; after adding water and the water reducing agent, stirring is performed for 4 to 8 minutes.

[0013] Furthermore, in S32), after the mixed mortar is poured into the mold, it is placed on a vibration table and vibrated for 20 to 30 seconds, and then the surface is flattened with a scraper, and the mold is removed after it is placed indoors for 20 to 28 hours.

[0014] Furthermore, in S33), the composite material specimen after demoulding is placed in a standard curing box for curing.

[0015] The advantages of the present invention are: 1. The present invention processes discarded fiberglass to obtain regenerated fibers, which are then heat-treated to obtain regenerated glass fibers. During the heat treatment, impurities on the fiber surface can be removed, surface defects can be reduced, and the glass fiber surface can be made smoother. At the same time, the amorphous structure of the glass fiber may be partially transformed into a crystalline state to form grains, making the fiber interior more tightly bonded. The glass molecules inside the fiber are more closely arranged and connected together, forming a stronger and denser structure, thereby enhancing the strength of the fiber and being able to withstand greater tensile stress when subjected to force. 2. The present invention applies the recycled glass fiber obtained above to cement-based composite materials, effectively inhibiting crack propagation within the cement matrix while improving the tensile strength, toughness, and durability of the material. In addition, the reuse of the recycled glass fiber can prevent the release of harmful substances in FRP solid waste, reduce environmental pollution, and achieve the recycling of resources in waste, thereby effectively reducing energy consumption. The preparation method of the recycled glass fiber cement-based composite material of the present invention can not only improve the mechanical properties and durability of the composite material, but also realize the effective recycling of discarded fan blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 Flowchart of the present invention. DETAILED DESCRIPTION

[0017] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0018] In the description of the present invention, it should be understood that the terms "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the invention.

[0019] The present invention provides a method for preparing a recycled glass fiber cement-based composite material, comprising the following steps: S1) preparing recycled glass fiber, specifically comprising the following steps: S11) mechanically crushing the discarded fiberglass reinforced plastic composite material to obtain a glass fiber composite matrix, and pyrolyzing the matrix to obtain regenerated fiber agglomerates; S12) screening and shearing the regenerated fiber mass to obtain regenerated fiber; S13) After drying pretreatment, the regenerated fiber is heat-treated at 550-650° C. to obtain regenerated glass fiber.

[0020] Specifically, the regenerated fibers are dried and pretreated through an oven, and heat-treated at 550-650 DEG C through a single-temperature-zone tubular furnace.

[0021] S2) preparing a regenerated glass fiber cement-based composite material, which comprises, by weight, 450-550 parts of cement, 1200-1400 parts of fine aggregate, 9-36 parts of regenerated glass fiber, 8-12 parts of water reducing agent, and 180-200 parts of water.

[0022] Specifically, the cement is portland cement.

[0023] Specifically, the fine aggregate is one or more of natural sand, artificial sand, or industrial slag.

[0024] Specifically, the fine aggregate has an apparent density of 2600-2650 kg / m 3 , and a particle size of 0.35-0.5 mm.

[0025] The present application also comprises step S3) of testing the performance of the regenerated glass fiber cement-based composite material, and preparing a composite material test piece from the regenerated glass fiber cement-based composite material, wherein the preparation of the composite material test piece specifically comprises the following steps, S31) adding sand, cement, and the regenerated glass fiber prepared in step S1) into a mortar mixer, stirring for a period of time, then adding water and water reducing agent, and continuing to stir. Specifically, the stirring time before adding water and water reducing agent is 25-45 s, and the stirring time after adding water and water reducing agent is 4-8 min.

[0026] S32) pouring the stirred mortar into a mold, vibrating and smoothing the surface, and placing in a room for a period of time before demolding. Specifically, after pouring the stirred mortar into the mold, the mold is placed on a vibration table for 20-30 s, and the surface is smoothed with a spatula, and the mold is demolded after being placed in a room for 20-28 hours.

[0027] S33) curing the demolded composite material test piece to a certain age, and then taking it out for relevant tests.

[0028] Specifically, the demolded composite material test piece is placed in a standard curing box for curing until the curing reaches the corresponding age, and then the test piece is taken out for relevant tests.

[0029] The present embodiment tests the mechanical properties, water absorption, and maximum water permeation pressure of the composite material test piece.

[0030] The mechanical property test is based on the provisions in “Cement mortar strength test method (ISO method)” (GB / T 17671-2021), and the test of the flexural strength and compressive strength of the test piece is carried out. The specific test steps are as follows: (1) Prepare 40x40x160mm prism test pieces, three for each group. The test pieces are cured under the condition of temperature (20±3)℃ and relative humidity above 90% to the specified age, and then tested by the compression and folding integrated machine; (2) Flexural strength determination: Place one side of the test piece on the support cylinder of the testing machine, with the long axis of the test piece perpendicular to the support cylinder. Apply a load uniformly at a rate of 50N±10N per second perpendicularly on the opposite side of the test piece until the test piece breaks. During the test, keep the two half test pieces in a humid state until the compression test is completed; (3) Compressive strength determination: After completing the flexural strength test, remove the two half test pieces for compressive strength test. Test on the side of the half test piece, ensuring that the deviation of the half test piece center from the compression center of the press plate is within ±0.5mm, while leaving about 10mm of prism exposed outside the press plate. During the entire loading process, apply the load uniformly at a rate of 2400N±200N per second until the test piece fails.

[0031] The water absorption test is based on the provisions in JGJ / T 70-2009 “Standard for testing methods of basic properties of building mortar”. The specific test steps are as follows: (1) Standard molding and curing test pieces, and removing the test pieces at 28 days, drying the test pieces at a temperature of 105±5℃ for 48±0.5 hours, and recording their mass as g0; (2) Place the test piece with the molding face facing down in the water tank, using two steel bars as support pads, and the test piece should be completely immersed in water, and the height of its upper surface from the water surface should not be less than 20mm. After 48±0.5 hours of immersion, remove it and wipe the surface moisture with a wrung wet cloth, and record its mass as g1; (3) The water absorption of the test piece should be calculated according to the following formula: Wx= [(g1- g0) / g0]x100%.

[0032] The maximum water permeation pressure test is based on the provisions in JGJ / T 70-2009 “Standard for testing methods of basic properties of building mortar”. The specific test steps are as follows: (1) Use a truncated cone-shaped bottom mold with an upper diameter of 70mm, a lower diameter of 80mm, and a height of 30mm to prepare the cement-based composite material test piece; (2) After the specimens have been molded and demolded for 28 days, their surfaces are completely dry. Then, they are sealed with sealing materials such as paraffin, rosin or butter and placed in a mortar penetrometer for a water-resistance test.

[0033] (3) At the beginning of the test, apply an initial pressure of 0.2 MPa and maintain a constant pressure for 2 hours; then increase the pressure to 0.3 MPa and increase it by 0.1 MPa every hour. If water seepage occurs on the surface of three or more specimens during this process, the test should be stopped immediately and the water pressure value at that time should be recorded. At the same time, if water seeps out from the periphery of the specimen during the test, the test should be stopped, the specimen should be resealed, and the test should be continued. In the process of controlling the pressure, the water penetration situation should be observed in time and the relevant data should be recorded, which can effectively evaluate the mortar's ability to resist water penetration.

[0034] Comparative Example First, add 1,300 parts sand and 500 parts cement to a mortar mixer and stir for 30 seconds. Once thoroughly mixed, add water and a water reducer and stir for 6 minutes. Then, pour the mixed mortar into a mold of the appropriate test size. Place the mold on a vibration table and vibrate for 20 seconds. After scraping the surface with a scraper, place the specimen indoors for 24 hours before removing it from the mold. After removal, place the specimen in a standard curing box and cure until it reaches the required age. Then, remove it for testing.

[0035] Example 1 The discarded FRP composite materials are mechanically crushed to obtain a glass fiber composite material matrix, which is then pyrolyzed to obtain regenerated fiber clusters. Regenerated fibers are obtained through screening and shearing process steps. The regenerated fibers are used as raw materials and are first pre-treated by oven drying. A single-temperature zone tubular furnace is used to perform surface heat treatment at 550°C to calcine the composite resin attached to the fiber surface to obtain regenerated glass fibers.

[0036] First, add 1,300 parts sand, 500 parts cement, and 9 parts recycled glass fiber to a mortar mixer and stir for 30 seconds. Once thoroughly mixed, add water and a water reducer and stir for 6 minutes. Then, pour the mixed mortar into a mold of the appropriate test size. Place the mold on a vibration table and vibrate for 20 seconds. After scraping the surface with a scraper, place the specimen indoors for 24 hours before removing it from the mold. After removal, place the specimen in a standard curing box and cure until it reaches the required age. Then, remove it for testing.

[0037] Example 2 The waste glass fiber reinforced plastic composite material is mechanically broken to obtain a glass fiber composite material matrix, and then pyrolysis is performed to obtain a regenerated fiber group. The regenerated fiber is obtained through screening and shearing process steps. The regenerated fiber is used as a raw material, is first dried by an oven drying pretreatment, is subjected to surface regulation by heat treatment at 550°C using a single-temperature-zone tube furnace, and is calcined to remove the composite resin attached to the surface of the fiber to obtain regenerated glass fiber.

[0038] In a mortar mixer, 1300 parts of sand, 500 parts of cement, and 18 parts of the regenerated glass fiber are first added and stirred for 30 seconds. After being uniformly mixed, water and a water reducing agent are added and stirred for 6 minutes. Subsequently, the stirred mortar is poured into a mold of a corresponding test size. The mold filled with the mortar is placed on a vibration table and vibrated for 20 seconds. After the surface is flattened with a spatula, the test piece is placed in a room for 24 hours before being demolded. The demolded test piece is placed in a standard curing box for curing until a corresponding age is reached. Subsequently, the test piece is taken out for related tests.

[0039] Example 3 The waste glass fiber reinforced plastic composite material is mechanically broken to obtain a glass fiber composite material matrix, and then pyrolysis is performed to obtain a regenerated fiber group. The regenerated fiber is obtained through screening and shearing process steps. The regenerated fiber is used as a raw material, is first dried by an oven drying pretreatment, is subjected to surface regulation by heat treatment at 550°C using a single-temperature-zone tube furnace, and is calcined to remove the composite resin attached to the surface of the fiber to obtain regenerated glass fiber.

[0040] In a mortar mixer, 1300 parts of sand, 500 parts of cement, and 27 parts of the regenerated glass fiber are first added and stirred for 30 seconds. After being uniformly mixed, water and a water reducing agent are added and stirred for 6 minutes. Subsequently, the stirred mortar is poured into a mold of a corresponding test size. The mold filled with the mortar is placed on a vibration table and vibrated for 20 seconds. After the surface is flattened with a spatula, the test piece is placed in a room for 24 hours before being demolded. The demolded test piece is placed in a standard curing box for curing until a corresponding age is reached. Subsequently, the test piece is taken out for related tests.

[0041] Example 4 The waste glass fiber reinforced plastic composite material is mechanically broken to obtain a glass fiber composite material matrix, and then pyrolysis is performed to obtain a regenerated fiber group. The regenerated fiber is obtained through screening and shearing process steps. The regenerated fiber is used as a raw material, is first dried by an oven drying pretreatment, is subjected to surface regulation by heat treatment at 550°C using a single-temperature-zone tube furnace, and is calcined to remove the composite resin attached to the surface of the fiber to obtain regenerated glass fiber.

[0042] The composite material specimens obtained in the above Comparative Example 1 and Examples 1-4 were cured for 7d and 28d, respectively, and their compressive strength and flexural strength were measured, as shown in Table 1 below.

[0043] The composite material specimens obtained in the above Comparative Example 1 and Examples 1-4 were cured for 7d and 28d, respectively, and their compressive strength and flexural strength were measured, as shown in Table 1 below.

[0044] Table 1 Compressive strength and flexural strength of composite material specimens As can be seen from Table 1, with the increase of the amount of recycled glass fiber, the mechanical properties of the recycled glass fiber cement-based composite material show a trend of first increasing and then decreasing. Compared with the specimen without adding fiber, the mechanical properties of the cement-based composite material specimen with 27 parts of recycled glass fiber are significantly improved. The compressive strength of the specimen is increased by 67.7% and 76.2% at 7 days and 28 days, respectively, and the flexural strength of the specimen is increased by 35.2% and 23.2% at 7 days and 28 days, respectively. This shows that the recycled glass fiber treated at 550°C applied to the cement-based composite material can produce the most significant effect on the mechanical properties.

[0045] The composite material specimens obtained in the above Comparative Example 1 and Examples 1-4 were cured for 7d and 28d, respectively, and their water absorption and maximum water permeation pressure were measured, as shown in Table 2 below.

[0046] Table 2 Water absorption and maximum water permeation pressure of composite material specimens As can be seen from Table 2, the fiber content is negatively correlated with the water absorption rate of the test piece, and the cumulative water absorption rate and water absorption of all test pieces decrease with the increase of curing time. With the increase of time, the pores in the mortar test piece are gradually filled with water, the friction between the water in the test piece and the capillary wall increases, which increases the resistance to the continuous entry of water into the test piece pores, and the test piece is gradually saturated with water. The water absorption rate of the early stage of the mortar test piece is obviously higher than that of the later stage of the mortar test piece. At the same time, with the increase of curing time, the compactness of the test piece increases, and the porosity decreases, so the water absorption capacity decreases, and the water absorption rate and water absorption gradually tend to be stable. Overall, the ordinary test piece without fiber has a higher water absorption rate, and the pore structure of the material is more developed, so water can more easily penetrate the material, causing leakage or permeability to decrease. The water absorption rate of the test piece with fiber increases more slowly with time, and the water absorption performance is significantly smaller than that of the cement-based composite material without fiber, indicating that the connectivity between pores is poor, and the pores in the cement matrix decrease with the increase of fiber content. Water is not easy to conduct and permeate in the material, and the material has good impermeability.

[0047] With the increase of fiber content, the maximum water permeation pressure value generally shows an increasing trend, and decreases slightly at the highest content. When the fiber content is 27 parts, the maximum water permeation pressure increases from 0.42 MPa of the ordinary test piece to 0.73 MPa, with a maximum growth rate of 73.8%. When the fiber content is 36 parts, the maximum water permeation pressure decreases slightly, but it is still significantly higher than that of the ordinary test piece. The slight decrease is mainly due to the uneven dispersion of a part of the fiber when the fiber content is too large, which leads to the deterioration of the network structure of the fiber and the increase of the pores of the cement-based composite material, resulting in a decrease in impermeability.

[0048] As can be seen from Table 2, the composite material test piece without adding recycled glass fiber has the maximum water absorption rate and the minimum maximum water permeation pressure compared with the composite material test piece with adding recycled glass fiber. Among them, the composite material test piece with adding 36 parts of recycled glass fiber in Example 4 has the minimum water absorption rate.

[0049] Therefore, the preparation method of the recycled glass fiber cement-based composite material of the present application can improve the mechanical properties and durability of the composite material.

[0050] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited by the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application should be equivalent replacement methods, and are included in the protection scope of the present application.

Claims

1. A method for preparing a recycled glass fiber cement-based composite material, characterized in that: The steps include: S1) preparing recycled glass fiber, specifically comprising the following steps: S11) mechanically crushing the discarded fiberglass reinforced plastic composite material to obtain a glass fiber composite matrix, and pyrolyzing the matrix to obtain regenerated fiber agglomerates; S12) screening and shearing the regenerated fiber mass to obtain regenerated fiber; S13) drying the regenerated fiber and then performing a heat treatment at 550-650° C. to obtain regenerated glass fiber; S2) preparing a recycled glass fiber cement-based composite material, wherein the recycled glass fiber cement-based composite material comprises 450-550 parts of cement, 1200-1400 parts of fine aggregate, 9-36 parts of recycled glass fiber, 8-12 parts of water reducer, and 180-200 parts of water based on 2000 parts by weight.

2. The method for preparing a recycled glass fiber cement-based composite material according to claim 1, wherein: In S13), the regenerated fiber is dried in an oven for pretreatment, and then heat-treated at 550-650° C. in a single-temperature-zone tubular furnace.

3. The method for preparing a recycled glass fiber cement-based composite material according to claim 1, wherein: In S2), the cement is Portland cement.

4. The method for preparing a recycled glass fiber cement-based composite material according to claim 3, wherein: In S2), the fine aggregate is one or more of natural sand, artificial sand or industrial ash.

5. The method for preparing a recycled glass fiber cement-based composite material according to claim 4, characterized in that: In S2), the apparent density of the fine aggregate is 2600~2650 kg / m 3 , particle size is 0.35~0.5 mm.

6. The method for preparing a recycled glass fiber cement-based composite material according to claim 1, wherein: The method further includes step S3), wherein the performance of the recycled glass fiber cement-based composite material is tested, and the recycled glass fiber cement-based composite material is prepared into a composite material specimen. The preparation of the composite material specimen specifically includes the following steps: S31) adding sand, cement, and the regenerated glass fiber prepared in step S1) into a mixer, stirring for a period of time, then adding water and a water reducing agent, and continuing to stir; S32) Pour the mixed mortar into the mold, vibrate and smooth the surface, and remove the mold after leaving it indoors for a period of time; S33) The composite material specimen after demoulding is cured to the age, and then taken out for relevant testing.

7. The method for preparing a recycled glass fiber cement-based composite material according to claim 6, characterized in that: In S31), stir for 25-45 seconds before adding water and water reducing agent; stir for 4-8 minutes after adding water and water reducing agent.

8. The method for preparing a recycled glass fiber cement-based composite material according to claim 7, wherein: In S32), after the mixed mortar is poured into the mold, it is placed on a vibration table and vibrated for 20 to 30 seconds, and then the surface is flattened with a scraper. After being placed indoors for 20 to 28 hours, the mold is removed.

9. The method for preparing a recycled glass fiber cement-based composite material according to claim 8, characterized in that: In S33), the composite material specimen after demoulding is placed in a standard curing box for curing.

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