Concrete based on recycled aggregate treatment and preparation method thereof

Abstract

The invention discloses a preparation method of concrete based on recycled aggregate treatment, and belongs to the technical field of concrete. The preparation method of the concrete based on recycled aggregate treatment comprises the following steps: S01, crushing building waste bricks, and carrying out physical screening and chemical strengthening pretreatment to obtain recycled aggregate; s02, mixing and stirring Portland cement, natural aggregate, natural fine aggregate, secondary fly ash, the recycled aggregate obtained in S01 and a polycarboxylate superplasticizer to obtain the concrete based on recycled aggregate treatment, the building waste bricks are prefabricated cement hollow bricks. According to the concrete based on recycled aggregate treatment, building waste bricks such as prefabricated cement hollow bricks are used as raw materials for preparing the recycled aggregate, and through the steps of physical screening and chemical strengthening pretreatment after smashing, the utilization rate of the recycled aggregate is increased, and the obtained concrete has excellent strength and durability; and recycling of construction waste such as prefabricated cement hollow bricks is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete, and in particular relates to concrete based on recycled aggregate processing and a preparation method thereof. Background Art

[0002] Aggregates are a crucial component of concrete, providing support and fill, and significantly impacting its strength, durability, and workability. Aggregates are generally divided into two categories: coarse aggregate and fine aggregate. Coarse aggregate typically includes crushed stone, pebbles, crushed bricks, and slag, while fine aggregate typically includes river sand, fly ash, and slag powder. Aggregate selection and optimization should be based on the specific requirements of the project, taking into account factors such as strength, workability, durability, and cost. Well-balanced aggregate grading can further enhance concrete performance.

[0003] Aggregate recycling involves processing discarded concrete, bricks, and other building materials into aggregates that can be used in concrete and other building materials. This process is crucial for resource recycling and environmental protection. However, recycled aggregates also present some challenges. For example, they typically have a lower density and higher water absorption, which can cause expansion and contraction during concrete use. Furthermore, recycled aggregates often contain numerous pores and microcracks, which can affect their strength and durability.

[0004] Precast hollow cement bricks are a common building material, offering advantages such as light weight, high strength, thermal insulation, and sound insulation. They are widely used in building walls and floor paving. However, the storage of discarded precast hollow cement bricks requires significant land resources, impacting the overall planning and aesthetics of cities. Summary of the Invention

[0005] In response to the above problems, the present invention proposes a concrete based on recycled aggregate processing and a preparation method thereof, which recycles construction waste bricks such as prefabricated cement hollow bricks. Through the physical screening and chemical strengthening pretreatment steps of the recycled aggregate, not only the utilization rate of the recycled aggregate is improved, but the obtained concrete also has excellent strength and durability.

[0006] The first aspect of the present invention is to disclose a method for preparing concrete based on recycled aggregate processing, comprising the following steps:

[0007] S01, crushing of construction waste bricks, physical screening and chemical strengthening pretreatment to obtain recycled aggregate;

[0008] S02, taking Portland cement, natural aggregate, natural fine aggregate, secondary fly ash, the recycled aggregate obtained in S01 and polycarboxylate water reducer, mixing and stirring to obtain the recycled aggregate-based concrete;

[0009] The construction waste bricks are prefabricated cement hollow bricks.

[0010] In some embodiments of the present invention, in S01, after the construction waste bricks are crushed, the aggregates with three particle sizes of 5-10mm, 10-20mm, and 20-50mm and the recycled brick powder with a particle size of less than 5mm are obtained through physical screening.

[0011] In some embodiments of the present invention, in S02, the weight ratio of the recycled aggregate obtained by mixing the three types of aggregates with small, medium and large particle sizes is (20-30): (20-30): (40-60).

[0012] In some embodiments of the present invention, in S01, the aggregates of small, medium and large particle sizes are respectively added with water glass, polyvinyl alcohol, recycled brick powder and soaked in water, then fished out, mixed with a silane coupling agent, and then vacuumed and pressurized.

[0013] In some embodiments of the present invention, in S01, the small-particle aggregate is added with recycled brick powder at a weight ratio of 8-10:1, and then soaked in a regeneration treatment liquid containing 25-35% w / v water glass and 25-35% w / v polyvinyl alcohol at a weight ratio of 1-2:1 for 12-24 hours, removed and allowed to stand for 1-3 hours, and a silane coupling agent is added at a weight ratio of 3:1, and then vacuumed to 0.01MPa, maintained for 5-10 minutes, and pressurized air is introduced, the pressure is increased to 0.3MPa, and maintained for 10-12 hours to obtain small-particle recycled aggregate.

[0014] In some embodiments of the present invention, in S01, the medium-sized aggregate is added with recycled brick powder at a weight ratio of 3-5:1, and then soaked in a regeneration treatment liquid containing 15-20% w / v water glass and 15-20% w / v polyvinyl alcohol at a weight ratio of 1-2:1 for 12-24 hours, removed and allowed to stand for 1-3 hours, silane coupling agent is added at a weight ratio of 5:1, and then vacuumed to 0.01MPa, maintained for 5-10 minutes, and pressurized air is introduced, the pressure is increased to 0.3MPa, and maintained for 10-12 hours to obtain small-sized recycled aggregate.

[0015] In some embodiments of the present invention, in S01, the large-particle aggregate is added with recycled brick powder at a weight ratio of 2-4:1, and then soaked in a regeneration treatment liquid containing 5-10% w / v water glass and 5-10% w / v polyvinyl alcohol at a weight ratio of 1-2:1 for 10-24 hours, removed and allowed to stand for 1-3 hours, and a silane coupling agent is added at a weight ratio of 3:1, and then vacuumed to 0.01MPa, maintained for 5-10 minutes, and pressurized air is introduced, the pressure is increased to 0.3MPa, and maintained for 10-12 hours to obtain small-particle recycled aggregate.

[0016] In some embodiments of the present invention, in S01, the waste construction bricks are sprayed with 5% by weight of tap water before being crushed.

[0017] In some embodiments of the present invention, the natural aggregate is 4-35 mm continuously graded pebbles, and the natural fine aggregate is medium sand for construction.

[0018] In some embodiments of the present invention, the weight ratio of the silicate cement, natural aggregate, natural fine aggregate, secondary fly ash, the recycled aggregate obtained from S01 and the polycarboxylate water reducer is 78-88:10-15:10-15:5-10:60-70:2.

[0019] The second aspect of the present invention is to disclose concrete prepared by the method for preparing concrete based on recycled aggregate processing described in the first aspect.

[0020] Beneficial effects of the present invention:

[0021] The concrete based on recycled aggregate processing of the present invention uses precast hollow cement bricks and other construction waste bricks as raw materials to prepare recycled aggregates. Through physical screening and chemical strengthening pretreatment steps after crushing, not only the utilization rate of the recycled aggregate is improved, but the obtained concrete also has excellent strength and durability, thereby realizing the recycling and utilization of precast hollow cement bricks and other construction waste.

[0022] In concrete structures, aggregate particle size, surface treatment, and degree of bonding with the matrix significantly influence the mechanical properties and durability of concrete. By treating recycled aggregate with varying concentrations of water glass and polyvinyl alcohol (PVA), combined with a silane coupling agent, the properties of the recycled aggregate can be significantly improved, thereby enhancing the overall performance of the concrete. For three different aggregate particle sizes derived from construction waste bricks, such as precast hollow cement bricks, the surface properties and interfacial bonding strength of the aggregates can be significantly improved by treating them with varying concentrations of water glass and polyvinyl alcohol (PVA) and a silane coupling agent. For coarse aggregate, which primarily bears the load in concrete, the water glass and PVA treatment repairs surface defects and enhances interfacial strength, significantly improving the compressive and flexural strengths of the concrete. For medium aggregate, which plays a transitional role in concrete, the treatment improves the workability and compactness of the concrete. The treatment results in a smoother surface and reduced porosity, contributing to improved impermeability and durability. For fine aggregates that mainly fill the voids in concrete, their surface activity is enhanced after treatment, allowing them to better combine with the cement matrix, thereby improving the overall strength and crack resistance of concrete. DETAILED DESCRIPTION

[0023] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0024] Unless otherwise specified, the examples and comparative examples are parallel experiments with the same components, component contents, preparation steps, and preparation parameters.

[0025] In the following examples and comparative examples, the precast hollow cement bricks are waste or recycled precast hollow cement bricks, and their main components are: CaO 15-20%, SiO2 45-50%, Al2O3 10-15%, MgO 5-10%, Na2O 1-2%, and SO2 0.1%. The water glass is national standard industrial water glass 40, with an active ingredient content of 40%, which is diluted to half the concentration of water to obtain a 20% w / v water glass. The polyvinyl alcohol is PVA1799 (100-27), with an active ingredient content of 99%. The silane coupling agent is KH550, with an active ingredient content of 99%.

[0026] Example 1

[0027] Concrete based on recycled aggregate processing and its preparation method include the following steps:

[0028] (1) Crushing and physical screening

[0029] Take prefabricated hollow cement bricks, spray them with 5 kg of water per 100 kg using a garden sprayer, and then crush them mechanically.

[0030] The crushed particles are divided into small-size aggregates (5-10mm) less than 10mm, medium-size aggregates (10-20mm) greater than 10mm and less than 20mm, large-size aggregates (20-50mm) greater than 20mm, and recycled brick powder less than 5mm;

[0031] (2) Chemical strengthening pretreatment

[0032] The obtained small-size aggregate, medium-size aggregate and large-size aggregate are respectively added with recycled brick powder and soaked in recycled water treatment liquid of water glass and polyvinyl alcohol. After being fished out, silane coupling agent is added, and vacuum and pressure treatment are performed to obtain three processed recycled aggregates with different particle sizes.

[0033] Specifically, 1 kg of recycled brick dust was added to every 10 kg of small-particle aggregate. The mixture was then soaked in 11 kg of Regeneration Liquid A (an aqueous solution containing 30% w / v water glass and 30% w / v polyvinyl alcohol) for 2 hours. After removal, the mixture was allowed to stand for 0.5 hours. A silane coupling agent, one-third of the total weight of the 11 kg small-particle aggregate and recycled brick dust, was added, amounting to 3.67 kg. The mixture was then vacuumed to 0.01 MPa for 5 minutes, then pressurized air was introduced, raising the pressure to 0.3 MPa and maintaining it for 10 hours to produce the small-particle recycled aggregate.

[0034] For every 10 kg of medium-sized aggregate, add 2 kg of recycled brick dust and soak in 12 kg of Regeneration Solution B (an aqueous solution containing 20% w / v water glass and 20% w / v polyvinyl alcohol) for 2 hours. Remove and let stand for 0.5 hours. Add one-fifth of the total weight of the medium-sized aggregate and recycled brick dust, or 2.4 kg, of a silane coupling agent. Then, evacuate to 0.01 MPa for 5 minutes, introduce pressurized air, increase the pressure to 0.3 MPa, and maintain for 10 hours to obtain small-sized recycled aggregate.

[0035] For every 10 kg of large-size aggregate, add 5 kg of recycled brick dust and soak in 15 kg of Regeneration Solution C (an aqueous solution containing 5% w / v water glass and 15% w / v polyvinyl alcohol) for 2 hours. Remove and let stand for 0.5 hours. Add 5.0 kg of silane coupling agent, one-third of the total weight of the large-size aggregate and recycled brick dust (15 kg). Then, evacuate to 0.01 MPa for 5 minutes, introduce pressurized air, raise the pressure to 0.3 MPa, and maintain for 10 hours to obtain small-size recycled aggregate.

[0036] (3) Take 88 parts by weight of Portland cement, 10 parts by weight of 4-35 mm continuously graded pebbles, 10 parts by weight of construction medium sand, 10 parts by weight of secondary fly ash, 15 parts by weight of small-size recycled aggregate, 15 parts by weight of medium-size recycled aggregate, 30 parts by weight of large-size recycled aggregate, and 2 parts by weight of polycarboxylate water reducer, mix and stir evenly to obtain concrete based on recycled aggregate treatment.

[0037] Example 2

[0038] Concrete based on recycled aggregate processing and its preparation method include the following steps:

[0039] (1) Crushing and physical screening

[0040] Take prefabricated hollow cement bricks, spray them with 5 kg of water per 100 kg using a garden sprayer, and then crush them mechanically.

[0041] The crushed particles are divided into small-size aggregates (5-10mm) less than 10mm, medium-size aggregates (10-20mm) greater than 10mm and less than 20mm, large-size aggregates (20-50mm) greater than 20mm, and recycled brick powder less than 5mm;

[0042] (2) Chemical strengthening pretreatment

[0043] The obtained small-size aggregate, medium-size aggregate and large-size aggregate are respectively added with recycled brick powder and soaked in recycled water treatment liquid of water glass and polyvinyl alcohol. After being fished out, silane coupling agent is added, and vacuum and pressure treatment are performed to obtain three processed recycled aggregates with different particle sizes.

[0044] Specifically, 1 kg of recycled brick dust was added to every 10 kg of small-particle aggregate. The mixture was then soaked in 11 kg of Regeneration Liquid A (an aqueous solution containing 20% w / v water glass and 30% w / v polyvinyl alcohol) for 2 hours. After removal, the mixture was allowed to stand for 0.5 hours. A silane coupling agent, one-third of the total weight of the 11 kg small-particle aggregate and recycled brick dust, was added, amounting to 3.67 kg. The mixture was then vacuumed to 0.01 MPa for 5 minutes, then pressurized air was introduced, raising the pressure to 0.3 MPa and maintaining it for 10 hours to produce the small-particle recycled aggregate.

[0045] For every 10 kg of medium-sized aggregate, add 2 kg of recycled brick dust and soak in 12 kg of Regeneration Solution B (an aqueous solution containing 20% w / v water glass and 23% w / v polyvinyl alcohol) for 2 hours. Remove and let stand for 0.5 hours. Add one-fifth of the total weight of the medium-sized aggregate and recycled brick dust, or 2.4 kg, of a silane coupling agent. Then, evacuate to 0.01 MPa for 5 minutes, introduce pressurized air, raise the pressure to 0.3 MPa, and maintain for 10 hours to obtain small-sized recycled aggregate.

[0046] For every 10 kg of large-size aggregate, add 5 kg of recycled brick dust and soak in 15 kg of Regeneration Solution C (an aqueous solution containing 5% w / v water glass and 12% w / v polyvinyl alcohol) for 2 hours. Remove and let stand for 0.5 hours. Add 5.0 kg of silane coupling agent, one-third of the total weight of 15 kg of large-size aggregate and recycled brick dust. Then, evacuate to 0.01 MPa for 5 minutes, introduce pressurized air, raise the pressure to 0.3 MPa, and maintain for 10 hours to obtain small-size recycled aggregate.

[0047] (3) Take 88 parts by weight of Portland cement, 10 parts by weight of 4-35 mm continuously graded pebbles, 10 parts by weight of construction medium sand, 10 parts by weight of secondary fly ash, 15 parts by weight of small-size recycled aggregate, 15 parts by weight of medium-size recycled aggregate, 30 parts by weight of large-size recycled aggregate, and 2 parts by weight of polycarboxylate water reducer, mix and stir evenly to obtain concrete based on recycled aggregate treatment.

[0048] Example 3

[0049] Concrete based on recycled aggregate processing and its preparation method include the following steps:

[0050] (1) Crushing and physical screening

[0051] Take prefabricated hollow cement bricks, spray them with 5 kg of water per 100 kg using a garden sprayer, and then crush them mechanically.

[0052] The crushed particles are divided into small-size aggregates (5-10mm) less than 10mm, medium-size aggregates (10-20mm) greater than 10mm and less than 20mm, large-size aggregates (20-50mm) greater than 20mm, and recycled brick powder less than 5mm;

[0053] (2) Chemical strengthening pretreatment

[0054] The obtained small-size aggregate, medium-size aggregate and large-size aggregate are respectively added with recycled brick powder and soaked in recycled water treatment liquid of water glass and polyvinyl alcohol. After being fished out, silane coupling agent is added, and vacuum and pressure treatment are performed to obtain three processed recycled aggregates with different particle sizes.

[0055] Specifically, 1 kg of recycled brick dust was added to every 10 kg of small-particle aggregate. The mixture was then soaked in 11 kg of Regeneration Liquid A (an aqueous solution containing 30% w / v water glass and 30% w / v polyvinyl alcohol) for 2 hours. After removal, the mixture was allowed to stand for 0.5 hours. A silane coupling agent, one-third of the total weight of the 11 kg small-particle aggregate and recycled brick dust, was added, amounting to 3.67 kg. The mixture was then vacuumed to 0.01 MPa for 10 minutes, then pressurized air was introduced, raising the pressure to 0.3 MPa and maintaining it for 10 hours to produce the small-particle recycled aggregate.

[0056] For every 10 kg of medium-sized aggregate, add 2 kg of recycled brick dust and soak in 12 kg of Regeneration Solution B (an aqueous solution containing 20% w / v water glass and 20% w / v polyvinyl alcohol) for 2 hours. Remove and let stand for 0.5 hours. Add one-fifth of the total weight of the medium-sized aggregate and recycled brick dust, or 2.4 kg, of a silane coupling agent. Then, evacuate to 0.01 MPa for 5 minutes, introduce pressurized air, raise the pressure to 0.3 MPa, and maintain for 12 hours to obtain small-sized recycled aggregate.

[0057] For every 10 kg of large-size aggregate, add 5 kg of recycled brick dust and soak in 15 kg of Regeneration Solution C (an aqueous solution containing 5% w / v water glass and 15% w / v polyvinyl alcohol) for 2 hours. Remove and let stand for 0.5 hours. Add 5.0 kg of silane coupling agent, one-third of the total weight of the large-size aggregate and recycled brick dust (15 kg). Then, evacuate to 0.01 MPa for 5 minutes, introduce pressurized air, raise the pressure to 0.3 MPa, and maintain for 10 hours to obtain small-size recycled aggregate.

[0058] (3) Take 88 parts by weight of Portland cement, 10 parts by weight of 4-35 mm continuously graded pebbles, 10 parts by weight of construction medium sand, 10 parts by weight of secondary fly ash, 15 parts by weight of small-size recycled aggregate, 15 parts by weight of medium-size recycled aggregate, 30 parts by weight of large-size recycled aggregate, and 2 parts by weight of polycarboxylate water reducer, mix and stir evenly to obtain concrete based on recycled aggregate treatment.

[0059] Example 4

[0060] Concrete based on recycled aggregate processing and its preparation method include the following steps:

[0061] (1) Crushing and physical screening

[0062] Take prefabricated hollow cement bricks, spray them with 5 kg of water per 100 kg using a garden sprayer, and then crush them mechanically.

[0063] The crushed particles are divided into small-size aggregates (5-10mm) less than 10mm, medium-size aggregates (10-20mm) greater than 10mm and less than 20mm, large-size aggregates (20-50mm) greater than 20mm, and recycled brick powder less than 5mm;

[0064] (2) Chemical strengthening pretreatment

[0065] The obtained small-size aggregate, medium-size aggregate and large-size aggregate are respectively added with recycled brick powder and soaked in recycled water treatment liquid of water glass and polyvinyl alcohol. After being fished out, silane coupling agent is added, and vacuum and pressure treatment are performed to obtain three processed recycled aggregates with different particle sizes.

[0066] Specifically, 1 kg of recycled brick dust was added to every 10 kg of small-particle aggregate. The mixture was then soaked in 11 kg of Regeneration Liquid A (an aqueous solution containing 30% water glass at a w / v concentration) for 2 hours. After removal, the mixture was allowed to stand for 0.5 hours. A silane coupling agent, one-third of the total weight of the 11 kg small-particle aggregate and recycled brick dust, was added, amounting to 3.67 kg. The mixture was then vacuumed to 0.01 MPa for 5 minutes, then pressurized air was introduced, raising the pressure to 0.3 MPa and maintaining it for 10 hours to produce the small-particle recycled aggregate.

[0067] For every 10 kg of medium-sized aggregate, add 2 kg of recycled brick dust and soak in 12 kg of Regeneration Solution B (an aqueous solution containing 20% water glass at a concentration of 20%) for 2 hours. Remove and allow to stand for 0.5 hours. Add one-fifth of the total weight of the medium-sized aggregate and recycled brick dust, or 2.4 kg, of a silane coupling agent. Then, evacuate to 0.01 MPa for 5 minutes, introduce pressurized air, raise the pressure to 0.3 MPa, and maintain for 10 hours to obtain small-sized recycled aggregate.

[0068] For every 10 kg of large-size aggregate, add 5 kg of recycled brick dust and soak in 15 kg of Regeneration Solution C (aqueous solution containing 5% water glass at a w / v concentration) for 2 hours. Remove and let stand for 0.5 hours. Add 5.0 kg of silane coupling agent, one-third of the total weight of the large-size aggregate and recycled brick dust (15 kg). Then, evacuate to 0.01 MPa for 5 minutes, introduce pressurized air, raise the pressure to 0.3 MPa, and maintain for 10 hours to obtain small-size recycled aggregate.

[0069] (3) Take 88 parts by weight of Portland cement, 10 parts by weight of 4-35 mm continuously graded pebbles, 10 parts by weight of construction medium sand, 10 parts by weight of secondary fly ash, 15 parts by weight of small-size recycled aggregate, 15 parts by weight of medium-size recycled aggregate, 30 parts by weight of large-size recycled aggregate, and 2 parts by weight of polycarboxylate water reducer, mix and stir evenly to obtain concrete based on recycled aggregate treatment.

[0070] Example 5

[0071] Concrete based on recycled aggregate processing and its preparation method include the following steps:

[0072] (1) Crushing and physical screening

[0073] Take prefabricated hollow cement bricks, spray them with 5 kg of water per 100 kg using a garden sprayer, and then crush them mechanically.

[0074] The crushed particles are divided into small-size aggregates (5-10mm) less than 10mm, medium-size aggregates (10-20mm) greater than 10mm and less than 20mm, large-size aggregates (20-50mm) greater than 20mm, and recycled brick powder less than 5mm;

[0075] (2) Chemical strengthening pretreatment

[0076] The obtained small-size aggregate, medium-size aggregate and large-size aggregate are respectively added with recycled brick powder and soaked in recycled water treatment liquid of water glass and polyvinyl alcohol. After being fished out, silane coupling agent is added, and vacuum and pressure treatment are performed to obtain three processed recycled aggregates with different particle sizes.

[0077] Specifically, 1 kg of recycled brick dust was added to every 10 kg of small-sized aggregate. The mixture was then soaked in 11 kg of Regeneration Liquid A (an aqueous solution containing 30% polyvinyl alcohol (w / v)) for 2 hours. The mixture was then removed and allowed to stand for 0.5 hours. A silane coupling agent, one-third of the total weight of the 11 kg small-sized aggregate and recycled brick dust, was added, amounting to 3.67 kg. The mixture was then vacuumed to 0.01 MPa for 5 minutes, then pressurized air was introduced, raising the pressure to 0.3 MPa and maintaining it for 10 hours to produce the small-sized recycled aggregate.

[0078] For every 10 kg of medium-sized aggregate, add 2 kg of recycled brick dust and soak in 12 kg of Regeneration Solution B (an aqueous solution containing 20% polyvinyl alcohol (w / v)) for 2 hours. Remove and allow to stand for 0.5 hours. Add one-fifth of the total weight of the medium-sized aggregate and recycled brick dust, or 2.4 kg, of a silane coupling agent. Then, evacuate to 0.01 MPa for 5 minutes, introduce pressurized air, raise the pressure to 0.3 MPa, and maintain for 10 hours to obtain small-sized recycled aggregate.

[0079] For every 10 kg of large-size aggregate, add 5 kg of recycled brick dust and soak in 15 kg of Regeneration Solution C (aqueous solution containing 15% polyvinyl alcohol (PVA)) for 2 hours. Remove and allow to stand for 0.5 hours. Add 5.0 kg of silane coupling agent, one-third of the total weight of the large-size aggregate and recycled brick dust (15 kg). Then, evacuate to 0.01 MPa for 5 minutes, introduce pressurized air, raise the pressure to 0.3 MPa, and maintain for 10 hours to obtain small-size recycled aggregate.

[0080] (3) Take 88 parts by weight of Portland cement, 10 parts by weight of 4-35 mm continuously graded pebbles, 10 parts by weight of construction medium sand, 10 parts by weight of secondary fly ash, 15 parts by weight of small-size recycled aggregate, 15 parts by weight of medium-size recycled aggregate, 30 parts by weight of large-size recycled aggregate, and 2 parts by weight of polycarboxylate water reducer, mix and stir evenly to obtain concrete based on recycled aggregate treatment.

[0081] Example 6

[0082] Concrete based on recycled aggregate processing and its preparation method include the following steps:

[0083] (1) Crushing and physical screening

[0084] Take prefabricated hollow cement bricks, spray them with 5 kg of water per 100 kg using a garden sprayer, and then crush them mechanically.

[0085] The crushed particles are divided into small-size aggregates (5-10mm) less than 10mm, medium-size aggregates (10-20mm) greater than 10mm and less than 20mm, large-size aggregates (20-50mm) greater than 20mm, and recycled brick powder less than 5mm;

[0086] (2) Chemical strengthening pretreatment

[0087] The obtained small-size aggregate, medium-size aggregate and large-size aggregate are respectively added with recycled brick powder and soaked in recycled water treatment liquid of water glass and polyvinyl alcohol. After being fished out, silane coupling agent is added, and vacuum and pressure treatment are performed to obtain three processed recycled aggregates with different particle sizes.

[0088] Specifically, 1 kg of recycled brick dust was added to every 10 kg of small-particle aggregate. The mixture was then soaked in 11 kg of Regeneration Liquid A (an aqueous solution containing 30% w / v water glass and 30% w / v polyvinyl alcohol) for 2 hours. After removal, the mixture was allowed to stand for 0.5 hours. A silane coupling agent, one-third of the total weight of the 11 kg small-particle aggregate and recycled brick dust, was added, amounting to 3.67 kg. The mixture was then vacuumed to 0.01 MPa for 5 minutes, then pressurized air was introduced, raising the pressure to 0.3 MPa and maintaining it for 10 hours to produce the small-particle recycled aggregate.

[0089] For every 10 kg of medium-sized aggregate, add 2 kg of recycled brick dust and soak in 12 kg of Regeneration Solution B (an aqueous solution containing 20% w / v water glass and 20% w / v polyvinyl alcohol) for 2 hours. Remove and let stand for 0.5 hours. Add one-fifth of the total weight of the medium-sized aggregate and recycled brick dust, or 2.4 kg, of a silane coupling agent. Then, evacuate to 0.01 MPa for 5 minutes, introduce pressurized air, increase the pressure to 0.3 MPa, and maintain for 10 hours to obtain small-sized recycled aggregate.

[0090] For every 10 kg of large-size aggregate, add 5 kg of recycled brick dust and soak in 15 kg of Regeneration Solution C (an aqueous solution containing 5% w / v water glass and 15% w / v polyvinyl alcohol) for 2 hours. Remove and let stand for 0.5 hours. Add 5.0 kg of silane coupling agent, one-third of the total weight of the large-size aggregate and recycled brick dust (15 kg). Then, evacuate to 0.01 MPa for 5 minutes, introduce pressurized air, raise the pressure to 0.3 MPa, and maintain for 10 hours to obtain small-size recycled aggregate.

[0091] (3) Take 88 parts by weight of Portland cement, 10 parts by weight of 4-35 mm continuously graded pebbles, 10 parts by weight of construction medium sand, 10 parts by weight of secondary fly ash, 17 parts by weight of small-size recycled aggregate, 18 parts by weight of medium-size recycled aggregate, 25 parts by weight of large-size recycled aggregate, and 2 parts by weight of polycarboxylate water reducer, mix and stir evenly to obtain concrete based on recycled aggregate treatment.

[0092] Comparative Example 1

[0093] A method for preparing concrete without recycled aggregate treatment comprises the following steps: taking 88 parts by weight of Portland cement, 30 parts by weight of 4-35 mm continuously graded pebbles, 30 parts by weight of construction sand, 30 parts by weight of secondary fly ash, and 2 parts by weight of a polycarboxylate water reducer, mixing and stirring the mixture to obtain concrete based on recycled aggregate treatment.

[0094] Comparative Example 2

[0095] The concrete based on recycled aggregate treatment and the preparation method thereof are different from those in Example 1 in that, in step (3), 88 parts by weight of Portland cement, 10 parts by weight of 4-35 mm continuously graded pebbles, 10 parts by weight of construction medium sand, 10 parts by weight of secondary fly ash, 30 parts by weight of small-particle recycled aggregate, 30 parts by weight of medium-particle recycled aggregate, and 2 parts by weight of polycarboxylate water reducer are mixed and stirred uniformly to obtain concrete based on recycled aggregate treatment.

[0096] Comparative Example 3

[0097] The concrete based on recycled aggregate treatment and the preparation method thereof are different from those in Example 1 in that, in step (3), 88 parts by weight of Portland cement, 10 parts by weight of 4-35 mm continuously graded pebbles, 10 parts by weight of construction medium sand, 10 parts by weight of secondary fly ash, 20 parts by weight of medium-sized recycled aggregate, 40 parts by weight of large-sized recycled aggregate, and 2 parts by weight of polycarboxylate water reducer are mixed and stirred uniformly to obtain concrete based on recycled aggregate treatment.

[0098] Comparative Example 4

[0099] The concrete based on recycled aggregate treatment and the preparation method thereof are different from those in Example 1 in that, in step (3), 88 parts by weight of Portland cement, 10 parts by weight of 4-35 mm continuously graded pebbles, 10 parts by weight of construction medium sand, 10 parts by weight of secondary fly ash, 20 parts by weight of small-particle recycled aggregate, 40 parts by weight of large-particle recycled aggregate, and 2 parts by weight of polycarboxylate water reducer are mixed and stirred uniformly to obtain concrete based on recycled aggregate treatment.

[0100] Comparative Example 5

[0101] The concrete based on recycled aggregate treatment and its preparation method are different from those in Example 1 in that both small-size aggregate and large-size aggregate adopt the treatment method of medium-size aggregate, that is,

[0102] For every 10 kg of small-size aggregate, add 2 kg of recycled brick dust and soak in 12 kg of Regeneration Solution B (an aqueous solution containing 20% w / v water glass and 20% w / v polyvinyl alcohol) for 2 hours. Remove and let stand for 0.5 hours. Add one-fifth of the total weight of the medium-size aggregate and recycled brick dust, or 2.4 kg, of a silane coupling agent. Then, evacuate to 0.01 MPa for 5 minutes, introduce pressurized air, raise the pressure to 0.3 MPa, and maintain for 10 hours to obtain small-size recycled aggregate.

[0103] For every 10 kg of large-sized aggregate, add 2 kg of recycled brick dust and soak in 12 kg of Regeneration Solution B (an aqueous solution containing 20% w / v water glass and 20% w / v polyvinyl alcohol) for 2 hours. Remove and let stand for 0.5 hours. Add one-fifth of the total weight of the large-sized aggregate and recycled brick dust, or 2.4 kg, of a silane coupling agent. Then, evacuate to 0.01 MPa for 5 minutes, introduce pressurized air, raise the pressure to 0.3 MPa, and maintain for 10 hours to obtain large-sized recycled aggregate.

[0104] Comparative Example 6

[0105] The concrete based on recycled aggregate treatment and the preparation method thereof are different from those in Example 1 in that the three types of aggregate treatment are not vacuumed or pressurized.

[0106] According to Section 6 of the compressive strength test of GB / T 50081-2002 Standard Method for Testing Mechanical Properties of Ordinary Concrete, the 28d strength was tested. The strength of Comparative Example 1 was taken as 100%, and the relative values of other embodiments and comparative examples were calculated. The results are shown in Table 1.

[0107] Table 1 Influence on strength properties

[0108] 28d strength 100% Example 1 135 Example 2 131 Example 3 132 Example 4 122 Example 5 117 Example 6 128 Comparative Example 1 100 Comparative Example 2 109 Comparative Example 3 107 Comparative Example 4 99 Comparative Example 5 101 Comparative Example 6 123

[0109] The results show that the concrete based on recycled aggregate treatment of the present invention, after physical screening after crushing and targeted different chemical strengthening pretreatments, has a performance that reaches or even exceeds that of concrete made entirely of natural aggregate and natural fine aggregate after 50% replacement of renewable aggregate.

[0110] In the preparation of recycled aggregate, the concentrations of water glass and polyvinyl alcohol in the regeneration solution, vacuum and pressure treatment, and different processing methods for the three raw material particle sizes significantly affect the strength properties of the resulting concrete. In addition, the raw materials of the three raw material particle sizes also significantly affect the strength properties of concrete.

[0111] The preferred specific implementation modes and embodiments of the present invention are described in detail above, but the present invention is not limited to the above implementation modes and embodiments. Various changes can be made within the scope of knowledge possessed by those skilled in the art without departing from the concept of the present invention.

Claims

1. A method for preparing concrete based on recycled aggregate processing, characterized in that: The following steps are involved: S01, crushing of construction waste bricks, physical screening and chemical strengthening pretreatment to obtain recycled aggregate; S02, taking Portland cement, natural aggregate, natural fine aggregate, secondary fly ash, the recycled aggregate obtained in S01 and polycarboxylate water reducer, mixing and stirring to obtain the recycled aggregate-based concrete; The construction waste bricks are prefabricated cement hollow bricks.

2. The method for preparing concrete based on recycled aggregate processing according to claim 1, characterized in that: In S01, after the construction waste bricks are crushed, the aggregates with three particle sizes of 5-10 mm, 10-20 mm, and 20-50 mm and the recycled brick powder with a particle size of less than 5 mm are obtained through physical screening; In S02, the weight ratio of the recycled aggregate obtained by mixing the three types of aggregates with small, medium and large particle sizes is (20-30): (20-30): (40-60).

3. The method for preparing concrete based on recycled aggregate processing according to claim 1 or 2, characterized in that: In S01, the aggregates of small, medium and large particle sizes are respectively added with water glass, polyvinyl alcohol, recycled brick powder and water, soaked, fished out, mixed with silane coupling agent, and then vacuumed and pressurized.

4. The method for preparing concrete based on recycled aggregate processing according to any one of claims 1 to 3, characterized in that: In S01, the small-particle aggregate is added with recycled brick powder at a weight ratio of 8-10:1, and then immersed in a regeneration treatment liquid containing 25-35% w / v water glass and 25-35% w / v polyvinyl alcohol at a weight ratio of 1-2:1 for 1-3 hours. After being fished out and allowed to stand for 0.5-1 hour, a silane coupling agent is added at a weight ratio of 3:1, and then vacuumed to 0.01MPa, maintained for 5-10 minutes, and pressurized air is introduced, the pressure is increased to 0.3MPa, and maintained for 10-12 hours to obtain small-particle recycled aggregate.

5. The method for preparing concrete based on recycled aggregate processing according to any one of claims 1 to 4, characterized in that: In S01, the medium-sized aggregate is added with recycled brick powder at a weight ratio of 3-5:1, and then soaked in a regeneration treatment liquid containing 15-20% w / v water glass and 15-20% w / v polyvinyl alcohol at a weight ratio of 1-2:1 for 12-24 hours. After being fished out and allowed to stand for 1-3 hours, a silane coupling agent is added at a weight ratio of 5:1, and then vacuumed to 0.01MPa, maintained for 5-10 minutes, and pressurized air is introduced, the pressure is increased to 0.3MPa, and maintained for 10-12 hours to obtain small-sized recycled aggregate.

6. The method for preparing concrete based on recycled aggregate processing according to any one of claims 1 to 5, characterized in that: In S01, the large-particle aggregate is added with recycled brick powder at a weight ratio of 2-4:1, and then immersed in a regeneration treatment liquid containing 5-10% w / v water glass and 5-10% w / v polyvinyl alcohol at a weight ratio of 1-2:1 for 10-24 hours. After being fished out and allowed to stand for 1-3 hours, a silane coupling agent is added at a weight ratio of 3:1, and then vacuumed to 0.01MPa, maintained for 5-10 minutes, and pressurized air is introduced, the pressure is increased to 0.3MPa, and maintained for 10-12 hours to obtain small-particle recycled aggregate.

7. The method for preparing concrete based on recycled aggregate processing according to any one of claims 1 to 6, characterized in that: In S01, the waste building bricks are sprayed with 5% by weight of tap water before being crushed.

8. The method for preparing concrete based on recycled aggregate processing according to any one of claims 1 to 7, characterized in that: The natural aggregate is 4-35 mm continuously graded pebbles, and the natural fine aggregate is medium sand for construction.

9. The method for preparing concrete based on recycled aggregate processing according to any one of claims 1 to 8, characterized in that: The weight ratio of the silicate cement, natural aggregate, natural fine aggregate, secondary fly ash, the recycled aggregate obtained from S01 and the polycarboxylate water reducer is 78-98:10-15:10-15:5-10:60-70:

2.

10. Concrete prepared according to the method for preparing concrete based on recycled aggregate processing according to any one of claims 1 to 9.