Recycled concrete and its preparation method and application

Abstract

The present application belongs to the technical field of recycled concrete, and particularly relates to a recycled concrete, a preparation method and application thereof. The present application breaks and recycles waste concrete blocks as coarse and fine aggregates of the recycled concrete, and obtains polypropylene particles by breaking and recycling plastic parts of retired automobile bumpers, which are used to fill the voids of the recycled concrete aggregates, reduce the void ratio of the recycled concrete, and improve the mechanical properties thereof. Moreover, the polypropylene particles have high ductility, can increase the workability of the recycled concrete, inhibit the shrinkage and cracking of the recycled concrete, and improve the corrosion resistance of the recycled concrete by utilizing the material properties of the polypropylene particles. The present application uses waste concrete blocks and plastic parts of retired automobile bumpers as raw material sources of the recycled concrete, can improve the utilization rate of waste concrete and plastic parts of retired automobile bumpers, realizes the economic value and resource recycling of the recycled concrete, and reduces environmental pollution.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of recycled concrete, and particularly relates to a recycled concrete and a preparation method and application thereof. BACKGROUND

[0002] With the vigorous development of the infrastructure construction industry and the automobile industry, the number of retired vehicles increases, and the supply and demand of concrete aggregates tend to be huge. A large amount of waste concrete garbage and retired vehicles are piled up, which not only occupies land and pollutes the environment, but also causes serious waste of resources. However, the proportion of polypropylene (PP) plastic used on the automobile continues to grow, and the research on recycling plastic parts of retired vehicles for recycled concrete aggregates can meet the requirements of the national policy on automobile recycling and utilization, and is also conducive to the sustainable development of the automobile industry.

[0003] Recycled concrete is a new energy-saving and environment-friendly material for solid waste utilization, which is a recycled building aggregate prepared by crushing, grading and preparing recycled concrete according to a certain ratio and process flow. Recycled concrete can be repeatedly used in engineering construction, and also solves the problems of insufficient concrete aggregates in engineering construction and pollution of the environment caused by waste concrete garbage landfill treatment. However, the recycled concrete prepared by the traditional method of recycling waste concrete has poor mechanical properties. SUMMARY

[0004] Therefore, the application provides a recycled concrete and a preparation method and application thereof. The recycled concrete provided by the application uses waste concrete broken particles as aggregate, and adds polypropylene particles obtained by crushing the plastic parts of the bumper of the retired vehicle, so that the recycled concrete has excellent mechanical properties and corrosion resistance, and can promote the recycling of waste resources and reduce environmental pollution.

[0005] In order to achieve the above-mentioned purpose, the application provides the following technical scheme:

[0006] The application provides a recycled concrete, which comprises the following preparation raw materials in mass parts:

[0007] recycled coarse aggregate 1200-1800 parts, recycled fine aggregate 500-800 parts, fly ash 260-300 parts, water 70-90 parts, cement 30-50 parts, polypropylene particles 10-30 parts, and high-efficiency water reducing agent 5-8 parts;

[0008] The preparation method of the recycled coarse aggregate and the recycled fine aggregate comprises the following steps:

[0009] The recycled coarse aggregate, the recycled fine aggregate and the unbroken concrete block are obtained by crushing and two-stage screening the recycled waste concrete block in sequence;

[0010] The preparation method of the polypropylene particles comprises the following steps:

[0011] The polypropylene particles are prepared by crushing, cleaning and drying the polypropylene material of the retired automobile bumper plastic parts in sequence.

[0012] Preferably, the particle size of the recycled coarse aggregate is >4.5mm and ≤9.5mm; and the particle size of the recycled fine aggregate is ≤4.5mm.

[0013] Preferably, the specific surface area of the fly ash is 160m 2 / kg, and the loss on ignition is 5-8%.

[0014] Preferably, the high-efficiency water-reducing agent comprises a melamine-based high-efficiency water-reducing agent or a polycarboxylic acid water-reducing agent.

[0015] Preferably, the particle size of the polypropylene particles is 0.5-1.5mm.

[0016] The application also provides a preparation method of the recycled concrete, comprising the following steps:

[0017] Mixing the cement and part of the water to perform first stirring to obtain a first mixture;

[0018] Mixing the first mixture, the fly ash and the polypropylene particles to perform second stirring to obtain a second mixture;

[0019] Mixing the second mixture, the recycled fine aggregate and the remaining water to perform third stirring to obtain a third mixture;

[0020] Mixing the third mixture and the recycled coarse aggregate to perform fourth stirring to obtain a fourth mixture;

[0021] Mixing the fourth mixture and the high-efficiency water-reducing agent to perform fifth stirring to obtain the recycled concrete.

[0022] Preferably, the first stirring time is 30-50s;

[0023] The second stirring time is 60-80s;

[0024] The third stirring time is 30-50s;

[0025] The fourth stirring time is 30-50s;

[0026] The fifth stirring time is 30-50s.

[0027] Preferably, the mass of the part of the water is 40-50% of the total mass of the water.

[0028] The application provides application of the recycled concrete prepared by the preparation method in a concrete prefabricated component.

[0029] Preferably, the preparation method of the concrete prefabricated component is placing the recycled concrete into a prefabricated component mold, curing and forming to obtain the concrete prefabricated component.

[0030] The recycled concrete is the recycled concrete prepared by the preparation method.

[0031] The application provides a recycled concrete, which is prepared from the following raw materials in mass parts: 1200-1800 parts of recycled coarse aggregate, 500-800 parts of recycled fine aggregate, 260-300 parts of fly ash, 70-90 parts of water, 30-50 parts of cement, 10-30 parts of polypropylene particles and 5-8 parts of high-efficiency water reducing agent. The preparation method of the recycled coarse aggregate and the recycled fine aggregate comprises the following steps: crushing and two-stage screening of recycled waste concrete blocks in sequence to obtain the recycled coarse aggregate, the recycled fine aggregate and incompletely crushed concrete blocks, respectively; and the incompletely crushed concrete blocks are returned to the crushing process. The preparation method of the polypropylene particles comprises the following steps: crushing, cleaning and drying of polypropylene material retired automobile bumper plastic parts in sequence to obtain polypropylene particles.

[0032] The application crushes recycled waste concrete blocks to serve as coarse and fine aggregates of the recycled concrete, and obtains polypropylene (PP) particles by crushing recycled retired automobile bumper plastic parts to fill the voids of the recycled concrete aggregates, reduce the void ratio of the recycled concrete, improve the mechanical properties of the recycled concrete, increase the workability of the recycled concrete due to the high ductility of the polypropylene (PP) particles, effectively inhibit segregation and bleeding of the recycled concrete mixture, reduce the voids between the coarse and fine aggregates of the recycled concrete, reduce the sinking of the aggregates, increase the overall density of the recycled concrete mixture, reduce the shrinkage and cracking of the recycled concrete due to temperature and moisture during later curing by using the good anti-shrinkage property of the polypropylene material, and improve the corrosion resistance of the recycled concrete by using the anti-corrosion property of the polypropylene (PP) particles.

[0033] Secondly, the application provides a preparation method of the recycled concrete. The application improves the microstructure defects of micro-cracks and pores in the recycled concrete prepared by the traditional single stirring process by adding the raw materials in batches during stirring, increases the density of the recycled concrete, and thus improves the mechanical properties of the recycled concrete. Attached Figure Description

[0034] Figure 1 This is a flowchart illustrating the method for preparing recycled concrete according to an embodiment of the present invention.

[0035] Figure 2 This is a diagram showing the order of adding raw materials during the preparation of recycled concrete in an embodiment of the present invention. Detailed Implementation

[0036] This invention provides a recycled concrete, comprising, by weight, the following raw materials:

[0037] 1200-1800 parts recycled coarse aggregate, 500-800 parts recycled fine aggregate, 260-300 parts fly ash, 70-90 parts water, 30-50 parts cement, 10-30 parts polypropylene granules, and 5-8 parts high-efficiency water-reducing agent.

[0038] The method for preparing the recycled coarse aggregate and recycled fine aggregate includes the following steps:

[0039] The recycled waste concrete blocks are crushed and screened in two stages to obtain recycled coarse aggregate, recycled fine aggregate and incompletely crushed concrete blocks, respectively.

[0040] The method for preparing the polypropylene particles includes the following steps:

[0041] The plastic parts of retired car bumpers made of polypropylene are crushed, cleaned, and dried in sequence to obtain polypropylene granules.

[0042] Unless otherwise specified, the present invention does not have special requirements on the source of the raw materials used in the preparation, and commercially available products well known to those skilled in the art can be used.

[0043] The recycled concrete provided by the present invention comprises, by weight, 1200 to 1800 parts of recycled coarse aggregate, preferably 1400 to 1600 parts.

[0044] In this invention, the particle size of the recycled coarse aggregate is preferably >4.5mm and ≤9.5mm, more preferably 5-9mm.

[0045] Based on 1 part by mass of recycled coarse aggregate in the raw materials for preparing recycled concrete, the raw materials for preparing recycled concrete provided by the present invention include 500 to 800 parts of recycled fine aggregate, preferably 600 to 700 parts.

[0046] In this invention, the particle size of the recycled fine aggregate is preferably ≤4.5mm, and more preferably ≤4mm.

[0047] In this invention, the method for preparing the recycled coarse aggregate and recycled fine aggregate includes the following steps:

[0048] The recycled waste concrete blocks are sequentially crushed and subjected to secondary screening to obtain recycled coarse aggregate, recycled fine aggregate and incompletely crushed concrete blocks.

[0049] In the present application, the crushing device is preferably a material crushing device with double production lines; the secondary screening device is preferably an aggregate particle screening device; the secondary screening is preferably sequentially performed through screens with a pore size of 4.5 mm and 9.5 mm; and the particle size of the incompletely crushed concrete blocks is preferably > 9.5 mm.

[0050] In the present application, the incompletely crushed concrete blocks are preferably returned to the crushing process.

[0051] Based on 1 part by mass of the recycled coarse aggregate in the raw material for preparing the recycled concrete, the raw material for preparing the recycled concrete provided by the present application comprises fly ash 260-300 parts, preferably 280-300 parts.

[0052] In the present application, the specific surface area of the fly ash is preferably 160 m 2 / kg, the loss on ignition is preferably 5-8%, and more preferably 6-8%.

[0053] Based on 1 part by mass of the recycled coarse aggregate in the raw material for preparing the recycled concrete, the raw material for preparing the recycled concrete provided by the present application comprises water 70-90 parts, preferably 80-90 parts.

[0054] Based on 1 part by mass of the recycled coarse aggregate in the raw material for preparing the recycled concrete, the raw material for preparing the recycled concrete provided by the present application comprises cement 30-50 parts, preferably 40-50 parts.

[0055] In the present application, the cement is preferably Portland cement P.C 42.5 or Portland cement P.O42.5R, and more preferably Portland cement P.C 42.5.

[0056] Based on 1 part by mass of the recycled coarse aggregate in the raw material for preparing the recycled concrete, the raw material for preparing the recycled concrete provided by the present application comprises polypropylene particles 10-30 parts, preferably 10-20 parts.

[0057] In the present application, the particle size of the polypropylene particles is preferably 0.5-1.5 mm, and more preferably 0.5-0.8 mm.

[0058] In the present application, the preparation method of the polypropylene particles comprises the following steps:

[0059] The retired automobile bumper plastic parts made of polypropylene material are sequentially crushed, washed and dried to obtain polypropylene particles.

[0060] In the present application, the crushing device is preferably a material crushing device with double production lines; the cleaning and drying device is preferably a cleaning and drying device; the cleaning liquid is preferably industrial water; the drying temperature is preferably 15-35 DEG C, more preferably 25-30 DEG C; and the drying time is preferably 10-20 h, more preferably 8-12 h.

[0061] The present application uses the polypropylene (PP) particles obtained by crushing the plastic parts of the retired automobile bumpers to fill the voids of the recycled concrete aggregate, reduces the void ratio of the recycled concrete, and improves the mechanical properties thereof.

[0062] In the present application, the preparation raw material of the recycled concrete includes 5-8 parts of high-efficiency water reducing agent, preferably 6-8 parts, based on 1 part of recycled coarse aggregate in the preparation raw material of the recycled concrete.

[0063] In the present application, the high-efficiency water reducing agent preferably includes melamine-based high-efficiency water reducing agent or polycarboxylic acid water reducing agent, more preferably melamine-based high-efficiency water reducing agent.

[0064] In the present application, the water-reducing rate of the melamine-based high-efficiency water reducing agent is preferably 15-20%, more preferably 18-20%; the melamine-based high-efficiency water reducing agent is preferably modified melamine-based high-efficiency water reducing agent; the brand of the modified melamine-based high-efficiency water reducing agent is Zhaojia, produced in Xuzhou, with water-reducing rate ≥21, total alkali content <8%, powder content (powder) <4, surface tension 71.5 mn / m, solid content 98±1%, and pH value 7-9; and the water-reducing rate of the polycarboxylic acid water reducing agent is preferably 20-35%, more preferably 30-35%.

[0065] The present application further provides a preparation method of the recycled concrete.

[0066] Mixing the cement and part of the water to perform first stirring to obtain a first mixture;

[0067] Mixing the first mixture, fly ash and polypropylene particles to perform second stirring to obtain a second mixture;

[0068] mixing the third mixture and recycled coarse aggregate, and performing fourth stirring to obtain a fourth mixture;

[0069] mixing the third mixture and recycled coarse aggregate, and performing fourth stirring to obtain a fourth mixture;

[0070] mixing the fourth mixture and high-efficiency water reducing agent, and performing fifth stirring to obtain recycled concrete.

[0071] The cement and part of the water are mixed to obtain a first mixture.

[0072] In the present application, the first stirring is preferably at a rate of 300-400 r / min, more preferably 350-400 r / min, and the first stirring is preferably for 30-50 s, more preferably 40-50 s.

[0073] In the present application, the part of the water preferably accounts for 40-50% of the total mass of the water, more preferably 45-50%.

[0074] After obtaining the first mixture, the first mixture, fly ash and polypropylene particles are mixed to obtain a second mixture.

[0075] In the present application, the second stirring is preferably at a rate of 300-400 r / min, more preferably 380-400 r / min, and the second stirring is preferably for 60-80 s, more preferably 70-80 s.

[0076] After obtaining the second mixture, the second mixture, recycled fine aggregate and the remaining water are mixed to obtain a third mixture.

[0077] In the present application, the third stirring is preferably at a rate of 300-400 r / min, more preferably 380-400 r / min, and the third stirring is preferably for 30-50 s, more preferably 40-50 s.

[0078] After obtaining the third mixture, the third mixture and recycled coarse aggregate are mixed to obtain a fourth mixture.

[0079] In the present application, the fourth stirring is preferably at a rate of 300-400 r / min, more preferably 380-400 r / min, and the fourth stirring is preferably for 30-50 s, more preferably 40-50 s.

[0080] After obtaining the fourth mixture, the fourth mixture and high-efficiency water reducing agent are mixed to obtain recycled concrete.

[0081] In the present application, the rate of the fifth stirring is preferably 300-400 r / min, more preferably 300-350 r / min; the time of the fifth stirring is 30-50 s, more preferably 40-50 s.

[0082] In the present application, the equipment used for the first stirring, the second stirring, the third stirring, the fourth stirring and the fifth stirring is preferably a multi-conveying-port stirring equipment; the equipment used for the first stirring, the second stirring, the third stirring, the fourth stirring and the fifth stirring is preferably a high-frequency vibration stirring.

[0083] The present application improves the microstructure defects of the recycled concrete prepared by the traditional single-stirring process, such as micro-cracks and pores, increases the compactness of the recycled concrete, and thus improves the mechanical properties thereof.

[0084] Figure 1 The flow chart of the preparation method of the recycled concrete of the present application is shown in FIG. 1. Figure 1 As shown in FIG. 1, the present application puts the recycled waste concrete blocks and the plastic parts of the retired automobile bumpers made of polypropylene into different production lines of the material crushing device with double production lines for crushing, then screens the obtained recycled concrete aggregate particles by using an aggregate particle screening equipment to obtain recycled coarse aggregate, recycled fine aggregate and incompletely crushed concrete blocks (return to crushing), puts the obtained mixture of the retired automobile bumper particles into a cleaning and drying device for cleaning and drying to obtain polypropylene particles, and puts the recycled coarse aggregate, the recycled fine aggregate, the polypropylene particles, industrial water, fly ash, cement and high-efficiency water reducing agent into a multi-conveying-port stirring equipment for stirring to obtain the recycled concrete.

[0085] Figure 2 The addition sequence diagram of the raw materials in the preparation of the recycled concrete in the present application is shown in FIG. 2. Figure 2 As shown in FIG. 2, the present application first adds cement and 50% water into the stirring device, high-frequency vibration stirs for 30 s, then adds fly ash and polypropylene particles, high-frequency vibration stirs for 60 s, then adds recycled fine aggregate and 50% water, high-frequency vibration stirs for 30 s, then adds recycled coarse aggregate, high-frequency vibration stirs for 30 s, and finally adds high-efficiency water reducing agent, high-frequency vibration stirs for 60 s.

[0086] The present application also provides the application of the recycled concrete prepared by the above technical solution or the preparation method to a concrete precast component.

[0087] In the present application, the preparation method of the concrete precast component is to put the recycled concrete into a precast component mold for curing and molding to obtain the concrete precast component.

[0088] The recycled concrete is the recycled concrete in the technical solution or the recycled concrete prepared by the preparation method in the technical solution.

[0089] In the application, the temperature of the curing molding is preferably 15-35℃, and more preferably 25-30℃; and the curing molding time is preferably 3-7d, and more preferably 7d.

[0090] The technical solutions in the application will be clearly and completely described below in combination with the embodiments in the application, but they should not be understood as limitations to the protection scope of the application.

[0091] Embodiment 1

[0092] A recycled concrete comprises the following preparation raw materials in mass parts: recycled coarse aggregate 1500 parts, recycled fine aggregate 600 parts, fly ash 260 parts, water 75 parts, cement 50 parts, polypropylene (PP) particles 10 parts, and high-efficiency water reducing agent 8 parts.

[0093] The particle size of the recycled coarse aggregate is 9mm, and the particle size of the recycled fine aggregate is 4mm; the specific surface area of the fly ash is 160m 2 / kg, and the loss on ignition is 7%; the high-efficiency water reducing agent is a melamine-based high-efficiency water reducing agent; and the particle size of the polypropylene (PP) particles is 0.8mm.

[0094] The preparation method comprises the following steps:

[0095] The recycled waste concrete blocks and the plastic parts of the retired automobile bumpers made of polypropylene are respectively placed in different production lines of a material crushing device with double production lines for crushing, and then the crushed recycled concrete aggregate particles are screened by an aggregate particle screening equipment to obtain recycled coarse aggregate, recycled fine aggregate and incompletely crushed concrete blocks (returned to crushing). The crushed retired automobile bumper particle mixture enters a cleaning and drying device for cleaning and drying to obtain polypropylene particles. The recycled coarse aggregate, the recycled fine aggregate, the polypropylene particles, industrial water, fly ash, cement and high-efficiency water reducing agent are placed in a conveying port stirring equipment for stirring. The addition sequence is: first, add cement and part of water (50% of the total water mass) and stir at 350r / min for 30s; then, add fly ash and polypropylene particles and stir at 350r / min for 60s; subsequently, add recycled fine aggregate and the remaining water and stir at 350r / min for 30s; then, add recycled coarse aggregate and stir at 350r / min for 30s; finally, add high-efficiency water reducing agent and stir at 350r / min for 60s to obtain recycled concrete.

[0096] Embodiment 2

[0097] A recycled concrete comprises the following mass parts of raw materials for preparation: recycled coarse aggregate 1800 parts, recycled fine aggregate 500 parts, fly ash 260 parts, water 70 parts, cement 45 parts, polypropylene (PP) particles 10 parts, and high-efficiency water reducing agent 6 parts.

[0098] The particle size of the recycled coarse aggregate is 9 mm, and the particle size of the recycled fine aggregate is 4 mm; the specific surface area of the fly ash is 160 m 2 / kg, and the loss on ignition is 7%; the high-efficiency water reducing agent is a polycarboxylic acid water reducing agent; the particle size of the polypropylene (PP) particles is 0.8 mm.

[0099] The preparation method comprises the following steps:

[0100] The recycled waste concrete blocks and the plastic parts of the retired automobile bumpers made of polypropylene are respectively placed in different production lines of a material crushing device with double production lines for crushing, and then the crushed recycled concrete aggregate particles are screened by an aggregate particle screening equipment to obtain recycled coarse aggregate, recycled fine aggregate, and incompletely crushed concrete blocks (returned to crushing). The crushed mixture of the retired automobile bumper particles enters a cleaning and drying device for cleaning and drying to obtain polypropylene particles. The recycled coarse aggregate, the recycled fine aggregate, the polypropylene particles, industrial water, fly ash, cement, and the high-efficiency water reducing agent are placed in a conveying port stirring equipment for stirring. The addition sequence is that the cement and part of the water (50% of the total water mass) are added first, stirred at 380 r / min for 30 s, then the fly ash and the polypropylene particles are added, stirred at 380 r / min for 60 s, then the recycled fine aggregate and the remaining water are added, stirred at 380 r / min for 30 s, then the recycled coarse aggregate is added, stirred at 380 r / min for 30 s, and finally the high-efficiency water reducing agent is added, stirred at 380 r / min for 60 s, to obtain the recycled concrete.

[0101] Example 3

[0102] A recycled concrete comprises the following mass parts of raw materials for preparation: recycled coarse aggregate 1800 parts, recycled fine aggregate 500 parts, fly ash 260 parts, water 70 parts, cement 45 parts, polypropylene (PP) particles 10 parts, and high-efficiency water reducing agent 6 parts.

[0103] The particle size of the recycled coarse aggregate is 9 mm, and the particle size of the recycled fine aggregate is 4 mm; the specific surface area of the fly ash is 160 m 2 / kg, and the loss on ignition is 7%; the high-efficiency water reducing agent is a polycarboxylic acid water reducing agent; the particle size of the polypropylene (PP) particles is 0.8 mm.

[0104] The preparation method comprises the following steps:

[0105] The recycled waste concrete block and the plastic part of the retired automobile bumper of polypropylene material are respectively placed in different production lines of the material crushing device with double production lines for crushing, then the recycled concrete aggregate particles obtained by crushing are screened by the aggregate particle screening equipment to obtain recycled coarse aggregate, recycled fine aggregate and incomplete broken concrete block (return to crushing), the mixture of the retired automobile bumper particles obtained by crushing enters the cleaning and drying device for cleaning and drying to obtain polypropylene particles, and the recycled coarse aggregate, the recycled fine aggregate, the polypropylene particles, the industrial water, the fly ash, the cement and the high-efficiency water reducing agent are placed in the multi-conveying port mixing equipment for stirring, and the adding sequence is that the cement and part of the water (50% of the total water quality) are added first, stirring at 400 r / min for 30 s, then the fly ash and the polypropylene particles are added, stirring at 400 r / min for 60 s, then the recycled fine aggregate and the remaining water are added, stirring at 400 r / min for 30 s, then the recycled coarse aggregate is added, stirring at 400 r / min for 30 s, and finally the high-efficiency water reducing agent is added, stirring at 400 r / min for 60 s, to obtain the recycled concrete.

[0106] Comparative Example 1

[0107] The difference from Example 1 is that the recycled coarse aggregate, the recycled fine aggregate, the fly ash, the water, the cement, the polypropylene (PP) particles and the high-efficiency water reducing agent are added together into the multi-conveying port mixing equipment for stirring at 350 r / min for 30 s to obtain the recycled concrete.

[0108] Comparative Example 2

[0109] The difference from Example 2 is that the recycled coarse aggregate, the recycled fine aggregate, the fly ash, the water, the cement, the polypropylene (PP) particles and the high-efficiency water reducing agent are added together into the multi-conveying port mixing equipment for stirring at 380 r / min for 30 s to obtain the recycled concrete.

[0110] Comparative Example 3

[0111] The difference from Example 3 is that the recycled coarse aggregate, the recycled fine aggregate, the fly ash, the water, the cement, the polypropylene (PP) particles and the high-efficiency water reducing agent are added together into the multi-conveying port mixing equipment for stirring at 400 r / min for 30 s to obtain the recycled concrete.

[0112] Application Example 1

[0113] The recycled concrete obtained in Example 1 is placed in a prefabricated component mold for curing and forming to obtain a concrete prefabricated component, which is a cube of 100 mm x 100 mm x 100 mm.

[0114] Application Example 2

[0115] The recycled concrete obtained in Example 2 is placed in a prefabricated component mold, and curing molding is performed to obtain a concrete prefabricated component, which is a cube of 100mmx100mmx100mm.

[0116] Application Example 3

[0117] The recycled concrete obtained in Example 3 is placed in a prefabricated component mold, and curing molding is performed to obtain a concrete prefabricated component, which is a cube of 100mmx100mmx100mm.

[0118] Application Example 4

[0119] The recycled concrete obtained in Example 1 is placed in a prefabricated component mold, and curing molding is performed to obtain a concrete prefabricated component.

[0120] Comparative Application Example 1

[0121] The difference from Application Example 1 is that the recycled concrete obtained in Example 1 is replaced by the recycled concrete of Comparative Example 1, and the rest is the same as Application Example 1.

[0122] Comparative Application Example 2

[0123] The difference from Application Example 2 is that the recycled concrete obtained in Example 2 is replaced by the recycled concrete of Comparative Example 2, and the rest is the same as Application Example 2.

[0124] Comparative Application Example 3

[0125] The difference from Application Example 3 is that the recycled concrete obtained in Example 3 is replaced by the recycled concrete of Comparative Example 3, and the rest is the same as Application Example 3.

[0126] Performance Test

[0127] (1) The compressive strength of the recycled concrete test piece prepared in different feeding sequences after curing for 7d is tested, and the specific parameters are shown in Table 1.

[0128] Table 1 Compressive strength value of recycled concrete test piece made by different feeding sequences

[0129] Serial number Additive order Test piece size / mm Curing time / d Compressive strength fc / Mpa Example 1 S4 100×100×100 7 36.25 Example 2 S4 100×100×100 7 36.22 Example 3 S4 100×100×100 7 36.84 Comparative Example 1 X1 100×100×100 7 34.26 Comparative Example 2 X1 100×100×100 7 34.85 Comparative Example 3 X1 100×100×100 7 34.35

[0130] As shown in Table 1, by setting the sequence of adding aggregate particles into the stirring device in batches, the microstructure defects of the recycled concrete prepared by the traditional single stirring process, such as microcracks and pores, are improved, the compressive strength value of the recycled concrete test piece is improved, the density of the recycled concrete mixture is increased, and the mechanical properties and durability of the recycled concrete are improved.

[0131] (2) The concrete prefabricated component prepared by the method of Example 4 has a strength grade of C20, a slump of 60 mm, and a permeability grade of P20.

[0132] (3) Taking a sulfate corrosion test as an example, the recycled concrete is made into a prism test piece with a size of 100mm*100mm*300mm, polypropylene (PP) particles are used as a test variable, and the compressive strength of the recycled concrete test piece after being soaked in the sulfate for 60 days is compared and analyzed under the same mixing amount, and the specific parameters are shown in Table 2.

[0133] Table 2 Compressive strength value of recycled concrete test piece in sulfate corrosion

[0134]

[0135] As shown in Table 2, the compressive strength of the recycled concrete test piece is improved by adding the polypropylene particles.

[0136] Although the above embodiment has made a detailed description of the present application, it is only a part of the embodiments of the present application but not all the embodiments, and other embodiments can be obtained according to the present embodiment without creativity, and these embodiments all belong to the protection scope of the present application.

Claims

1. Recycled concrete, characterized in that, The following raw materials are included in mass parts: The recycled coarse aggregate 1500 parts, the recycled fine aggregate 600 parts, the fly ash 260 parts, the water 75 parts, the cement 50 parts, the polypropylene particles 10 parts, and the high-efficiency water reducing agent 8 parts; The particle size of the recycled coarse aggregate is 9 mm, and the particle size of the recycled fine aggregate is 4 mm; the specific surface area of the fly ash is 160 m 2 / kg, the loss on ignition is 7%; the high-efficiency water reducing agent is a melamine-based high-efficiency water reducing agent; the particle size of the polypropylene particles is 0.8 mm; The preparation method of the recycled concrete comprises the following steps: The recycled waste concrete blocks and the plastic parts of the retired automobile bumpers made of polypropylene material are respectively placed in different production lines of a material crushing device with double production lines for crushing, then the crushed recycled concrete aggregate particles are screened by an aggregate particle screening equipment to obtain recycled coarse aggregate, recycled fine aggregate, and incompletely crushed concrete blocks, the incompletely crushed concrete blocks are returned to crushing, the crushed retired automobile bumper particle mixture is put into a cleaning and drying device for cleaning and drying to obtain polypropylene particles, and the recycled coarse aggregate, the recycled fine aggregate, the polypropylene particles, industrial water, fly ash, cement, and the high-efficiency water reducing agent are placed in the conveying port of a stirring equipment for stirring, the adding sequence is that the cement and part of the water are added first, the mass of the part of the water is 50% of the total water mass, stirring is carried out at 350 r / min for 30 s, then the fly ash and the polypropylene particles are added and stirring is carried out at 350 r / min for 60 s, subsequently the recycled fine aggregate and the remaining water are added and stirring is carried out at 350 r / min for 30 s, then the recycled coarse aggregate is added and stirring is carried out at 350 r / min for 30 s, finally the high-efficiency water reducing agent is added and stirring is carried out at 350 r / min for 60 s, to obtain the recycled concrete.

2. The application of the recycled concrete of claim 1 in a concrete precast component.

3. Use according to claim 2, characterized in that, The preparation method of the concrete precast component is that the recycled concrete is placed in a precast component mold for curing and forming to obtain the concrete precast component.

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