Modification method of brick-mixed recycled aggregate

Abstract

The invention discloses a brick-concrete recycled aggregate modification method, which comprises: collecting brick-concrete building solid waste, and carrying out crushing and screening pretreatment to obtain a brick-concrete recycled aggregate; a waste BOPP film strip is wound on the surface of recycled aggregate to complete aggregate pretreatment, the pretreated brick-concrete recycled aggregate is placed in an aggregate drying oven, and the surface of the brick-concrete recycled aggregate is coated with a BOPP film through micro hot melting; cooling the hot-melt brick-mixed recycled aggregate coated with the BOPP film to a preset temperature, smearing an interface binder on the surface, and dipping and wrapping the brick-mixed recycled aggregate in high-strength polymer mortar; and cooling and curing the brick-concrete recycled aggregate coated with the high-strength polymer mortar, and performing standard curing to finish the modification of the recycled aggregate. By means of the scientific and efficient method, the physical and mechanical properties of the brick-concrete recycled aggregate are remarkably improved, and sustainable utilization of resources and environmental protection are achieved.

Description

Technical Field

[0001] The invention belongs to the field of building materials, and in particular relates to a method for modifying brick-concrete recycled aggregate. Background Art

[0002] With the rapid advancement of urbanization, a large number of existing civil brick-concrete structures have been demolished, resulting in a large amount of construction waste, which has caused serious environmental pollution. In recent years, with the enhancement of people's environmental awareness and the advancement of mechanical automation technology, people have begun to try to process construction solid waste into recycled aggregates with uniform particle size and try to mix them into natural aggregates, aiming to achieve the reuse of construction solid waste resources.

[0003] At present, a large number of studies are being conducted on the application of recycled aggregates for brick-concrete and the mechanical properties of recycled concrete. The research of scholars has reached a general conclusion that the recycled aggregates for brick-concrete have a particle size similar to that of natural aggregates and can fully meet the requirements of concrete grading. However, the recycled aggregates for brick-concrete generally have the characteristics of low elastic modulus, high crushing index, and high water absorption. The recycled concrete made of recycled aggregates for brick-concrete also generally has defects such as insufficient strength, poor durability, and poor freeze-thaw resistance. This seriously limits the application of recycled aggregates for brick-concrete. Design departments and engineering construction units dare not easily try this new type of recycled concrete because of the lack of theoretical basis support for recycled concrete.

[0004] In response to the above problems, many scholars have tried to modify brick-concrete recycled aggregates, aiming to change the inherent disadvantages of brick-concrete recycled aggregates through various means and methods, so as to achieve the stability of recycled concrete performance and realize that recycled aggregate concrete can have similar performance to ordinary concrete. For example, in the patent document with publication number CN116730642A, a method for modifying recycled aggregates by recycling alginate polymers from urban sludge is disclosed. Although this method can effectively utilize urban sludge and alginate polymers, in actual operation, the complexity of the components of sludge and polymers may lead to unstable modification effects; at the same time, this method may require specific processing equipment and process conditions, which increases costs and technical difficulties. For another example, in the patent document with publication number CN221798044U, a new type of assembled cement-stabilized recycled aggregate pavement base is disclosed. The design, construction and connection technology of the patented assembled structure are not yet mature, which may affect the stability and durability of the pavement; the source and quality differences of the recycled aggregates may lead to different modification effects, affecting the overall performance of the pavement. For example, the patent document with publication number CN101074152 discloses a method for modifying recycled aggregate using tung oil as a modifier. Although this method is innovative, the cost of tung oil as a modifier is relatively high, which may limit the wide application of this method. Secondly, the reaction conditions and control parameters in the tung oil modification process may be relatively complex, increasing the difficulty and cost of production.

[0005] In summary, it is urgent to propose an environmentally friendly, low-carbon, reliable and stable performance brick-concrete recycled aggregate modification method to better realize the recycling of construction solid waste resources. Summary of the invention

[0006] In view of the above-mentioned technical problems, the present invention provides a method for modifying brick-concrete recycled aggregate. The method modifies the brick-concrete recycled aggregate based on externally applied logistics waste BOPP material and high-strength polymer mortar, thereby forming an innovative modified brick-concrete recycled aggregate.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] A method for modifying brick-concrete recycled aggregate is carried out according to the following steps:

[0009] S1: Collect brick-concrete construction solid waste, and crush and screen it to obtain brick-concrete recycled aggregate;

[0010] S2: Wash and dry the brick-concrete recycled aggregate, collect the discarded BOPP strips in the Internet logistics, and wrap the BOPP strips around the surface of the recycled aggregate;

[0011] S3: placing the brick-concrete recycled aggregate wrapped with BOPP strips in an aggregate oven, and coating the BOPP strips on the surface of the brick-concrete recycled aggregate by micro-thermal melting to form a BOPP external coating film;

[0012] S4: After cooling the brick-concrete recycled aggregate with BOPP external coating to a preset temperature, apply an interface adhesive on the surface and then dip it into high-strength polymer mortar;

[0013] S5: The brick-concrete recycled aggregate coated with high-strength polymer mortar is cooled and solidified and subjected to standard curing to complete the modification of the recycled aggregate.

[0014] Furthermore, the particle size of the brick-concrete recycled aggregate after pretreatment in step S1 ranges from 10 mm to 20 mm.

[0015] Furthermore, in step S2, the pre-treated brick-concrete recycled aggregate is wrapped with a BOPP strip in an independent unit of 500 g to 1000 g.

[0016] Furthermore, in step S3, the micro-melting temperature of the aggregate oven is 150-170°C, so that the BOPP strips are tightly and evenly coated on the surface of the brick-concrete recycled aggregate to form a BOPP external coating film.

[0017] Furthermore, the winding thickness of the BOPP tape is 0.1 mm to 0.2 mm.

[0018] Furthermore, the interface adhesive is epoxy resin, and the coating thickness is 1-2 mm.

[0019] Furthermore, the thickness of the outer mortar is controlled between 1 and 2 mm.

[0020] Furthermore, in step S4, the brick-concrete recycled aggregate with the BOPP external coating is first cooled to 50-60° C., and then an interface adhesive is applied on the surface.

[0021] Furthermore, the standard curing in step S5 means that the temperature is controlled at 20±2° C. and the relative humidity is maintained at above 95%.

[0022] The beneficial effects of the present invention are:

[0023] (1) The performance of solid waste aggregates is significantly improved: Through the dual modification of external BOPP material and high-strength polymer mortar, the bonding properties of brick-concrete recycled aggregates are greatly enhanced, the crushing value index is effectively reduced, and the water absorption rate is also significantly reduced, thereby significantly improving its overall mechanical properties and service life.

[0024] (2) Efficient utilization of resources: The present invention makes full use of the construction solid waste generated in the process of urbanization and the waste BOPP materials commonly used in logistics in the Internet era, realizing the resource utilization of waste, which not only reduces environmental pollution, but also saves raw material resources and promotes the development of the circular economy.

[0025] (3) Simple and easy process: The modification process is relatively simple and does not involve complex chemical reactions or high temperature and high pressure treatments, which reduces production costs and technical difficulties, making this method easier to promote and apply in industrial production.

[0026] (4) Significant environmental benefits: The modified brick-concrete recycled aggregate has better durability and environmental performance, and can reduce the impact on the environment during use. It is in line with the current green and low-carbon development concept and helps promote the sustainable development of the construction industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 A flow chart of a brick-concrete recycled aggregate modification method provided by an embodiment of the present invention;

[0028] Figure 2 A detailed diagram of the brick-concrete recycled aggregate provided by an embodiment of the present invention;

[0029] Figure 3 A detailed diagram of a modified brick-concrete aggregate coated with hot-melt BOPP provided in an embodiment of the present invention;

[0030] Figure 4 This is an appearance diagram of a brick-concrete recycled aggregate coated with BOPP material provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0032] Example: In order to better realize the recycling of construction solid waste resources, the example of the present application discloses a method for modifying brick-concrete recycled aggregate, aiming to provide a method for modifying brick-concrete recycled aggregate based on an externally coated BOPP (biaxially oriented polypropylene film) material. This method utilizes the construction solid waste generated in the process of urbanization - brick-concrete recycled aggregate, combined with the common waste BOPP materials in logistics in the Internet era, and high-strength polymer mortar, to form an innovative modified brick-concrete recycled aggregate. This method not only realizes the effective utilization of construction waste, but also significantly enhances the adhesion of brick-concrete recycled aggregate through the dual effects of the BOPP hot coating layer and the high-strength polymer mortar outer coating layer, reduces its crushing value index and water absorption rate, thereby realizing the effective modification of brick-concrete recycled aggregate, and providing a new solution for the sustainable development of building materials. The method involves the following key components and steps:

[0033] Brick-concrete recycled aggregate 1: It comes from the construction solid waste generated by the demolition of masonry structures in the process of urbanization, and is processed into granular brick-concrete recycled aggregate with uniform particle size and stable quality through fine mechanical processing.

[0034] BOPP outer coating layer 2: Utilizing BOPP (biaxially oriented polypropylene film) materials such as discarded bundling tapes commonly found in the logistics process in the Internet era, the materials are evenly wrapped on the surface of the brick-concrete recycled aggregate through micro-hot melt softening technology to form a tightly fitting and bond-enhancing BOPP outer coating layer 2.

[0035] High-strength polymer mortar 3 outer coating: Put the red brick recycled aggregate wrapped with BOPP material into the oven for baking. After the BOPP material is hot-melted, a layer of high-strength polymer mortar will be adhered to the aggregate. When the BOPP material is baked to the hot-melt state, it is tightly combined with the high-strength polymer mortar.

[0036] Specifically, Figure 1 The brick-concrete recycled aggregate modification method provided in this embodiment has the following specific steps:

[0037] S1. Collect and process construction solid waste to prepare brick-concrete recycled aggregate 1, and pre-treat the brick-concrete recycled aggregate 1 by crushing and screening.

[0038] Specifically, we can collect the old brick-concrete construction waste from the urbanization process, and after crushing, screening and other processes, we can obtain Figure 2 The particle size range shown meets the requirements of the brick-concrete recycled aggregate. Preferably, the particle size range is between 10mm and 20mm, which can ensure that the hot-melt BOPP material is evenly attached to the surface of the brick-concrete aggregate, more effectively compacting the pores of the brick recycled aggregate and significantly improving the performance of the modified recycled aggregate, such as compressive strength and impermeability. This step ensures the uniformity and applicability of the raw materials and lays the foundation for the subsequent modification process.

[0039] S2: The pre-treated brick-concrete recycled aggregate is cleaned and dried, and waste BOPP strips in Internet logistics are collected and wrapped around the surface of the recycled aggregate.

[0040] Specifically, the pretreated brick-concrete recycled aggregate can be taken as an independent unit of about 500 grams to 1000 grams, and the discarded BOPP strips collected from the Internet logistics waste can be wrapped around the surface of the recycled aggregate of each independent unit, thereby realizing the resource utilization of waste, which not only reduces environmental pollution, but also saves raw material resources and promotes the development of the circular economy.

[0041] It should be noted that the key to this step is to ensure close contact between the BOPP strip and the aggregate, so as to form good bonding force in the subsequent curing process and enhance the modification effect. In order to achieve a close fit between the BOPP material and the aggregate, preferably, a BOPP strip with a thickness of 0.1 mm to 0.2 mm can be used. The film of this thickness has good thermoplasticity and adhesion. The BOPP strip is tightly and evenly wrapped on the surface of the aggregate by mechanical means (such as rollers or vacuum adsorption equipment) or manual methods (such as manual pressing and brushing of hot melt adhesive) to ensure that there are no bubbles and wrinkles. In particular, the pressure and temperature can be precisely controlled by mechanical devices to achieve the best fit between the BOPP strip and the aggregate surface, so as to form good bonding force in the subsequent hot melt curing process, for example Figure 3 shown.

[0042] S3. Place the brick-concrete recycled aggregate wrapped with BOPP strips in an aggregate oven, and coat the BOPP strips on the aggregate surface by micro-thermal melting to form a BOPP outer coating layer 2.

[0043] Specifically, the brick-concrete recycled aggregate wrapped with BOPP strips is placed in a special aggregate oven, the micro-thermal melting temperature of the aggregate oven is 150-170° C. The BOPP strips are tightly and evenly coated on the aggregate surface by micro-thermal melting to form a BOPP outer coating layer 2.

[0044] S4. After cooling the brick-concrete recycled aggregate with BOPP external coating to a preset temperature, apply an interface adhesive on the surface and then dip it into the high-strength polymer mortar 3.

[0045] An optional implementation manner is to first cool the recycled aggregate with the BOPP external coating to a temperature of 50-60°C, then apply an interface adhesive on the surface, and then dip it into the high-strength polymer mortar 3, and then naturally cool and solidify the treated aggregate and perform standard curing.

[0046] It is understandable that the interface adhesive will further enhance the bonding force between the BOPP material and the aggregate. Therefore, a small amount of interface adhesive can be applied on the surface of the brick-concrete recycled aggregate of the BOPP outer coating film, for example, a 1-2 mm thick epoxy resin interface adhesive can be applied to increase the surface viscosity.

[0047] Furthermore, the aggregate coated with the binder is placed in the mixed high-strength polymer mortar. The thickness of the outer coating mortar is generally controlled between 1-2 mm to ensure sufficient bonding strength and coating effect.

[0048] Specifically, Figure 4 As shown, the brick-concrete recycled aggregate 1 wrapped with BOPP strips is placed in an oven for baking. When the BOPP strips reach a completely hot-melt state at a temperature of about 150°C to 170°C, that is, the film becomes transparent and soft, with no obvious sticky residue, the temperature of the recycled aggregate with the hot-melt BOPP outer coating is reduced to 50-60°C, a small amount of interface adhesive is applied on the surface of the aggregate, and the recycled aggregate is placed in a high-strength polymer mortar 3 and evenly coated.

[0049] It should be noted that the high-strength polymer mortar is made by mixing polymer emulsion, cement, sand and other raw materials in a specific proportion, which ensures that the mortar has excellent bonding, impermeability and durability. Since the high-strength polymer mortar has high adhesion and strength, it ensures that the recycled aggregate after treatment has high compressive strength.

[0050] It is understandable that BOPP material is a linear polymer material with thermoplasticity. When BOPP material is heated to 150℃ to 170℃, it will be in a plastic state and produce greater viscosity. It is suitable for bonding with the high-strength polymer mortar applied externally with the assistance of an interface adhesive. The hot-melt BOPP material will be evenly attached to the surface of the brick aggregate, which can effectively compact the pores of the recycled brick aggregate, increase the stiffness and bonding properties of the aggregate, and save construction costs. When the BOPP strip is baked to a hot melt state, it is tightly combined with the high-strength polymer mortar. This mortar has extremely high adhesion and strength, which can ensure that the red brick recycled aggregate can withstand various environmental tests while maintaining its integrity. At this time, the BOPP external coating film forms a protective layer, and the high-strength polymer mortar is evenly applied to the outer layer of the aggregate, ensuring that each piece of aggregate is evenly covered and fixed.

[0051] The brick-concrete recycled aggregate modification method based on external BOPP material provided in this embodiment aims to significantly improve the physical and mechanical properties of brick-concrete recycled aggregate through a scientific and efficient method, realize the sustainable utilization of resources and environmental protection, and provide a new technical path for the efficient utilization of construction waste. This method not only has the advantages of simple operation and low cost, but also has high technical feasibility and practical application value, providing strong support for the sustainable development of the construction industry.

[0052] S5. The brick-concrete recycled aggregate coated with high-strength polymer mortar is naturally cooled and solidified and subjected to standard curing to complete the modification of the recycled aggregate.

[0053] Specifically, the curing of the wrapped aggregate can be completed according to the technical requirements provided by the existing high-strength polymer mortar manufacturers, such as controlling the temperature at 20±2°C and maintaining the relative humidity at above 95%.

[0054] The modified brick-concrete recycled aggregate after maintenance in this application is promoted and applied, and can be widely used in construction, roads, gardens and other fields to replace traditional aggregates, achieve resource recycling and environmental sustainable development.

[0055] The above embodiments are only preferred implementation modes of the present invention. It should be pointed out that ordinary technicians in this technical field can make several improvements and equivalent substitutions without departing from the principles of the present invention. These technical solutions after improvements and equivalent substitutions to the claims of the present invention all fall within the protection scope of the present invention.

Claims

1. A method for modifying recycled aggregates for brick-concrete, characterized in that , follow the steps below: S1: Collect brick-concrete construction solid waste, and crush and screen it to obtain brick-concrete recycled aggregate; S2: washing and drying the pretreated brick-concrete recycled aggregate, collecting the discarded BOPP strips in the Internet logistics, and wrapping the BOPP strips around the surface of the recycled aggregate; S3: placing the brick-concrete recycled aggregate wrapped with BOPP strips in an aggregate oven, and coating the BOPP strips on the surface of the brick-concrete recycled aggregate by micro-thermal melting to form a BOPP external coating film; S4: After cooling the brick-concrete recycled aggregate with BOPP external coating to a preset temperature, apply an interface adhesive on the surface and then dip it into high-strength polymer mortar; S5: The brick-concrete recycled aggregate coated with high-strength polymer mortar is cooled and solidified and subjected to standard curing to complete the modification of the recycled aggregate.

2. The modification method according to claim 1, characterized in that: The particle size of the brick-concrete recycled aggregate after pretreatment in step S1 ranges from 10 mm to 20 mm.

3. The modification method according to claim 1, characterized in that: In step S2, the pre-treated brick-concrete recycled aggregate is wrapped with a BOPP strip in an independent unit of 500 to 1000 grams.

4. The modification method according to claim 1 or 3, characterized in that: In step S3, the micro-melting temperature of the aggregate oven is 150-170°C, so that the BOPP strips are tightly and evenly coated on the surface of the brick-concrete recycled aggregate to form a BOPP external coating film.

5. The modification method according to claim 1, characterized in that: The winding thickness of the BOPP tape is 0.1 mm to 0.2 mm.

6. The modification method according to claim 1, characterized in that: The interface adhesive is epoxy resin, and the coating thickness is 1-2 mm.

7. The modification method according to claim 1, characterized in that: The thickness of the outer mortar is controlled between 1-2 mm.

8. The modification method according to claim 1, characterized in that: In step S4, the brick-concrete recycled aggregate with the BOPP outer coating is first cooled to 50-60° C., and then an interface adhesive is applied on the surface.

9. The modification method according to claim 1, characterized in that: In step S5, standard curing means that the temperature is controlled at 20±2°C and the relative humidity is maintained above 95%.

Images