CN115490464A - C30 recycled aggregate concrete and preparation method thereof - Google Patents

C30 recycled aggregate concrete and preparation method thereof Download PDF

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Publication number
CN115490464A
CN115490464A CN202211065050.9A CN202211065050A CN115490464A CN 115490464 A CN115490464 A CN 115490464A CN 202211065050 A CN202211065050 A CN 202211065050A CN 115490464 A CN115490464 A CN 115490464A
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China
Prior art keywords
recycled
aggregate
modified
coarse aggregate
water
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CN202211065050.9A
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Chinese (zh)
Inventor
曲东杰
廖京
王彬
金磊
王羽中
付强
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Beijing Tiandi Construction Concrete Products Co ltd
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Beijing Tiandi Construction Concrete Products Co ltd
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Priority to CN202211065050.9A priority Critical patent/CN115490464A/en
Publication of CN115490464A publication Critical patent/CN115490464A/en
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    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B18/00—Use of agglomerated or waste materials or refuse as fillers for mortars, concrete or artificial stone; Treatment of agglomerated or waste materials or refuse, specially adapted to enhance their filling properties in mortars, concrete or artificial stone
    • C04B18/04—Waste materials; Refuse
    • C04B18/16—Waste materials; Refuse from building or ceramic industry
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
    • C04B20/02—Treatment
    • C04B20/023—Chemical treatment
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00017—Aspects relating to the protection of the environment
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/20—Mortars, concrete or artificial stone characterised by specific physical values for the density
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
    • C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W30/00—Technologies for solid waste management
    • Y02W30/50—Reuse, recycling or recovery technologies
    • Y02W30/91—Use of waste materials as fillers for mortars or concrete

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Civil Engineering (AREA)
  • Inorganic Chemistry (AREA)
  • Environmental & Geological Engineering (AREA)
  • General Chemical & Material Sciences (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)

Abstract

The application relates to the technical field of concrete, and particularly discloses C30 recycled aggregate concrete and a preparation method thereof, wherein the recycled aggregate concrete comprises the following raw materials in parts by weight: 40-50 parts of cement, 10-23 parts of fly ash, 20-30 parts of fine aggregate, 70-90 parts of modified recycled coarse aggregate, 1-5 parts of water reducing agent, 1-5 parts of auxiliary agent and water, wherein the water-to-glue ratio is 0.49-0.55; the modified recycled coarse aggregate is prepared by soaking and modifying recycled coarse aggregate with modified slurry, wherein the modified slurry comprises cement, metakaolin, sodium silicate, sodium hydroxide and water. The modified recycled coarse aggregate is applied to the C30 recycled aggregate concrete, natural coarse aggregate can be replaced by the modified recycled coarse aggregate, the recycled coarse aggregate is highly utilized, and meanwhile, the strength of the C30 recycled aggregate concrete can be maintained.

Description

C30 recycled aggregate concrete and preparation method thereof
Technical Field
The application relates to the technical field of concrete, in particular to C30 recycled aggregate concrete and a preparation method thereof.
Background
With the rapid development of economy and the acceleration of urbanization process in China, the construction industry is developed vigorously, and the quantity of construction wastes generated by construction and demolition is huge every year and accounts for about 40% of industrial solid wastes, and most of the construction wastes are waste concrete. At present, the treatment modes of waste concrete mainly comprise two types: firstly, the material is simply used as a backfill material or directly buried; and the second is used as recycled aggregate. However, the landfill treatment not only occupies a large amount of land, but also causes pollution to shallow ground surfaces, rivers, underground water and the like, the landfill cost is high, and in addition, the natural gravels are widely exploited all the time, so that a series of environmental ecological problems and embarrassment that resources face exhaustion are caused, and the waste concrete is advocated to be recycled.
The recycling of the waste concrete is to crush and screen the waste concrete to obtain recycled aggregate, and then apply the recycled aggregate to the fresh concrete, thereby saving natural aggregate. The recycled aggregate can be divided into fully recycled aggregate, recycled coarse aggregate and recycled fine aggregate. The quality of the fully recycled aggregate is not easy to control, so in practical application, the fully recycled aggregate is generally screened into recycled coarse aggregate and recycled fine aggregate which are screen residue and screen underflow obtained after the recycled full aggregate is screened by a 4.75mm square-hole screen.
The inventor finds that in the recycled concrete on the market, the replacement rate of the recycled coarse aggregate to the natural coarse aggregate is only 30-50%, and the utilization rate of the recycled coarse aggregate is low.
Disclosure of Invention
In order to improve the utilization rate of the recycled coarse aggregate, the application provides C30 recycled aggregate concrete and a preparation method thereof.
In a first aspect, the present application provides a C30 recycled aggregate concrete, which adopts the following technical scheme:
the C30 recycled aggregate concrete comprises the following raw materials in parts by weight:
40-50 parts of cement, 10-23 parts of fly ash, 20-30 parts of fine aggregate, 70-90 parts of modified recycled coarse aggregate, 1-5 parts of water reducing agent, 1-5 parts of auxiliary agent and water;
the water-to-glue ratio is 0.49-0.55;
the modified recycled coarse aggregate is prepared by soaking and modifying recycled coarse aggregate with modified slurry, wherein the modified slurry comprises cement, metakaolin, sodium silicate, sodium hydroxide and water, and the mass ratio of the cement to the metakaolin to the sodium silicate to the sodium hydroxide to the water is (7-12): (10-17): (3-6): (5-9): (35-50).
By adopting the technical scheme, the modified recycled coarse aggregate is obtained by modifying the recycled coarse aggregate through the modified slurry, and the modified recycled coarse aggregate is applied to the C30 recycled aggregate concrete, so that the natural coarse aggregate can be replaced by the modified recycled coarse aggregate, the recycled coarse aggregate is highly utilized, and meanwhile, the performance of the C30 recycled aggregate concrete can be maintained.
In this application, the coarse aggregate concrete is modified with the modified thick liquid that cement, metakaolin, sodium silicate, sodium hydroxide and water cooperation obtained, can improve the sturdiness and the workability of regeneration coarse aggregate to improve the compressive strength and the constructability of regeneration concrete.
In the application, when the modified slurry is used for soaking the recycled coarse aggregate, the modified slurry can be used for completely soaking the recycled coarse aggregate, and further preferably, the mass ratio of the modified slurry to the recycled coarse aggregate is 1: (6.7-9.2), in this case, the raw material cost can be saved while the performance of the modified recycled coarse aggregate is ensured, and the efficiency of preparing the modified recycled coarse aggregate can be improved to a certain extent.
Preferably, the mass ratio of the cement to the metakaolin to the sodium silicate to the sodium hydroxide to the water is (7-10): (12-17): (5-6): (7-9): (35-42). Most preferably, the mass ratio of the cement, the metakaolin, the sodium silicate, the sodium hydroxide and the water is 10:15:5:8:40.
by adopting the technical scheme, the proportion of each component of the modified slurry is optimized, so that the modified recycled coarse aggregate with better performance can be obtained, and the modified recycled coarse aggregate can be favorably used for replacing the natural coarse aggregate in percentage without influencing the performance of recycled concrete.
Preferably, the regenerated coarse aggregate adopts 4.75-31.5mm continuous gradation, wherein 20% -25% of the aggregate with the particle size of 4.75-9.5mm, 32% -36% of the aggregate with the particle size of 9.5-16mm, 10% -15% of the aggregate with the particle size of 16-19mm, 21% -27% of the aggregate with the particle size of 19-26.5mm and 0.2% -0.8% of the aggregate with the particle size of 26.5-31.5 mm.
More preferably, 23.8% of the total particles having a particle diameter of 4.75 to 9.5mm, 35.6% of the total particles having a particle diameter of 9.5 to 16mm, 13.4% of the total particles having a particle diameter of 16 to 19mm, 25.6% of the total particles having a particle diameter of 19 to 26.5mm, and 0.48% of the total particles having a particle diameter of 26.5 to 31.5 mm.
By adopting the technical scheme, the proportion of each particle size range of the recycled coarse aggregate is adjusted and controlled, the gradation of the recycled coarse aggregate can be optimized, and the apparent density and the porosity of the recycled coarse aggregate are improved, so that the performance of the recycled coarse aggregate is improved, and the recycled coarse aggregate is favorable for replacing natural coarse aggregate in percentage.
Preferably, the fine aggregate is at least one selected from modified recycled fine aggregate and natural river sand. Preferably, the aggregate is modified recycled fine aggregate.
By adopting the technical scheme, the influence of the fine aggregate selected and modified recycled fine aggregate or natural river sand on the compressive strength of the recycled concrete is small, so that the fine aggregate is preferably modified and recycled in the application from the aspects of environmental protection and reasonable utilization of waste resources.
Preferably, the modified recycled fine aggregate is prepared by soaking recycled fine aggregate in a cement soaking solution, and the cement soaking solution comprises cement, fly ash and water.
Preferably, the mass ratio of the cement to the fly ash to the water is (6-10): (1-2): (8-15). Further preferably, the mass ratio of the cement to the fly ash to the water is 8.
By adopting the technical scheme, the fine aggregate is treated by the cement slurry prepared from the cement, the fly ash and the water in a certain ratio, so that the performance of the fine aggregate can be improved, and the construction performance and the compressive strength of the recycled concrete can be improved.
In the application, the cement soak solution completely soaks the recycled fine aggregate, and further preferably, the mass ratio of the cement soak solution to the recycled fine aggregate is 1: (4.7-6.2), preferably 1:5, in this case, the material cost can be saved while the performance of the modified regenerated fine aggregate is ensured.
Preferably, the recycled fine aggregate is in 0.15-4.75mm continuous gradation, wherein 18-22% of the recycled fine aggregate with the particle size of 0.15-0.3mm, 23-27.3% of the recycled fine aggregate with the particle size of 0.3-0.6mm, 26-30% of the recycled fine aggregate with the particle size of 0.6-1.18mm, 10-16% of the recycled fine aggregate with the particle size of 1.18-2.36mm and 5-10% of the recycled fine aggregate with the particle size of 2.36-4.75 mm.
Further preferably, 21.4% of the particles having a particle diameter of 0.15 to 0.3mm, 25.9% of the particles having a particle diameter of 0.3 to 0.6mm, 28.4% of the particles having a particle diameter of 0.6 to 1.18mm, 15.8% of the particles having a particle diameter of 1.18 to 2.36mm, and 8.5% of the particles having a particle diameter of 2.36 to 4.75 mm.
By adopting the technical scheme, the proportion of each particle size range of the recycled fine aggregate is controlled in the range, and the gradation of the recycled fine aggregate can be optimized. In the application, the grading of the recycled coarse aggregate and the recycled fine aggregate are mutually matched, the strength of the concrete is not influenced when the recycled aggregate percentage is used for replacing the natural aggregate, and in addition, the anti-carbonization capacity of the concrete can be improved.
The apparent density and the porosity of the recycled coarse aggregate are improved, so that the performance of the recycled coarse aggregate is improved, and the recycled coarse aggregate is favorable for replacing natural coarse aggregate.
Preferably, the auxiliary agent is selected from at least one of DPS waterproofing agent and crack resistance agent.
By adopting the technical scheme, the DPS waterproof agent is added, and can rapidly permeate into the cement mixture and react with alkali substances to generate water-insoluble gel, so that the internal pores are blocked, the capillary pore channels are sealed, the compactness is increased, a reliable waterproof layer is formed, the waterproof concrete has the functions of sealing, resisting water, moisture, wind erosion, carbonization, acid and alkali erosion and the like, and the strength of the concrete can be improved. In the application, the DPS waterproof emulsion with the content of the effective substances of more than or equal to 75 percent is adopted.
The anti-cracking agent is added to improve the anti-cracking capacity of the concrete, and in the application, the anti-cracking agent is preferably anti-cracking fiber.
When the auxiliary agent is DPS waterproofing agent and anti-cracking agent, the dosage ratio of DPS waterproofing agent and anti-cracking agent is (1-2.3) to 1.
In a second aspect, the application provides a preparation method of C30 recycled aggregate concrete, which adopts the following technical scheme:
a preparation method of C30 recycled aggregate concrete comprises the following steps:
pre-wetting the modified recycled coarse aggregate with water, and then uniformly stirring the pre-wetted modified recycled coarse aggregate with cement, fly ash and fine aggregate to obtain a dry blend;
adding a water reducing agent and an auxiliary agent into water, and uniformly stirring to obtain a mixed solution;
and mixing the dry mixture and the mixed solution, and uniformly stirring to obtain the recycled aggregate concrete.
By adopting the technical scheme, the preparation method is simple, convenient to operate and easy to implement.
Preferably, the preparation of the modified recycled coarse aggregate comprises the following steps:
according to the formula proportion, sodium silicate and sodium hydroxide are poured into water and stirred uniformly, then the mixture is kept stand and aged for 2-4 hours, and metakaolin and cement are added and stirred uniformly to obtain modified slurry;
and uniformly stirring the recycled coarse aggregate and the modified slurry, and curing and air-drying under natural conditions to obtain the modified recycled coarse aggregate.
By adopting the technical scheme, the prepared modified recycled coarse aggregate is homogeneous and stable.
Preferably, the preparation of the modified recycled fine aggregate comprises the following steps:
uniformly mixing cement and fly ash according to a formula ratio, then adding water, and uniformly stirring to obtain a cement soak solution;
soaking the recycled fine aggregate in a cement soak solution, stirring once every 20-30min, and stopping soaking until cement slurry is coagulated on the surface of the recycled fine aggregate;
filtering with 5mm square mesh sieve after soaking, keeping on 5mm square mesh sieve for 10-20min, shaking every 3-5min, maintaining all undersize under natural condition, and air drying to obtain modified regenerated fine aggregate.
In summary, the present application has the following beneficial effects:
1. according to the application, the coarse aggregate concrete is modified by using modified slurry obtained by mixing cement, metakaolin, sodium silicate, sodium hydroxide and water according to a formula proportion to obtain modified recycled coarse aggregate, the modified recycled coarse aggregate is applied to the C30 recycled aggregate concrete, the natural coarse aggregate can be replaced by the modified recycled coarse aggregate, the recycled coarse aggregate is high in utilization rate, and meanwhile, the strength of the C30 recycled aggregate concrete can be kept;
2. in the application, the cement soaking solution obtained by mixing cement, fly ash and water according to the formula proportion is used for treating the recycled fine aggregate to obtain the modified recycled fine aggregate, and the modified recycled fine aggregate can replace natural aggregate in percentage without basically influencing the performance of C30 concrete;
3. in the application, the grading of the recycled coarse aggregate and the recycled fine aggregate is optimized, the recycled coarse aggregate and the recycled fine aggregate are favorably filled with each other, the void ratio and the total surface area of the aggregates can be reduced, the unit water consumption and the cement consumption of the recycled concrete can be effectively reduced, the compressive strength, the compactness and the workability of the recycled concrete are improved, the recycled aggregate is favorably used for replacing the natural aggregate, and the utilization rate of the recycled aggregate is greatly improved.
Detailed Description
The present application will be described in further detail with reference to examples. Specifically, the following are described: the following examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer; the starting materials used in the following examples are all those conventionally commercially available except where specifically noted.
Examples of preparation of modified recycled coarse aggregate
In preparation examples 1 to 4 of the modified recycled coarse aggregate, 4.75 to 31.5mm continuous gradation of the recycled coarse aggregate is adopted, wherein 23.8% of the recycled coarse aggregate having a particle size of 4.75 to 9.5mm, 35.6% of the recycled coarse aggregate having a particle size of 9.5 to 16mm, 13.4% of the recycled coarse aggregate having a particle size of 16 to 19mm, 25.6% of the recycled coarse aggregate having a particle size of 19 to 26.5mm, and 0.48% of the recycled coarse aggregate having a particle size of 26.5 to 31.5 mm.
Preparation of modified recycled coarse aggregate example 1
The modified recycled coarse aggregate 1 was prepared as follows:
pouring 120g of sodium silicate and 180g of sodium hydroxide into 1000g of water, uniformly stirring, standing and aging for 4h, adding 340g of metakaolin and 240g of cement, and fully and uniformly stirring to obtain modified slurry;
17296g of the recycled coarse aggregate and the modified slurry are uniformly stirred, and are cured and air-dried under natural conditions to prepare the modified recycled coarse aggregate 1.
Preparation example 2 of modified recycled coarse aggregate
The modified recycled coarse aggregate 2 was prepared as follows:
pouring 60g of sodium silicate and 100g of sodium hydroxide into 750g of water, uniformly stirring, standing and aging for 2h, adding 240g of metakaolin and 140g of cement, and fully and uniformly stirring to obtain modified slurry;
8308g of recycled coarse aggregate and the modified slurry are uniformly stirred, and are maintained and air-dried under natural conditions, so that the modified recycled coarse aggregate 2 is prepared.
Preparation example 3 of modified recycled coarse aggregate
The modified recycled coarse aggregate 3 was prepared as follows:
pouring 100g of sodium silicate and 160g of sodium hydroxide into 800g of water, uniformly stirring, then standing and aging for 3h, adding 300g of metakaolin and 200g of cement, and fully and uniformly stirring to obtain modified slurry;
11000g of recycled coarse aggregate and the modified slurry are uniformly stirred, and are cured and air-dried under natural conditions to prepare modified recycled coarse aggregate 3.
Preparation example 4 of modified recycled coarse aggregate
The modified recycled coarse aggregate 4 was prepared as follows:
pouring 80g of sodium silicate and 140g of sodium hydroxide into 840g of water, uniformly stirring, standing and aging for 3h, adding 240g of metakaolin and 200g of cement, and fully and uniformly stirring to obtain modified slurry;
11000g of recycled coarse aggregate and the modified slurry are uniformly stirred, and are maintained and air-dried under natural conditions, so that the modified recycled coarse aggregate 4 is prepared.
Preparation example 5 of modified recycled coarse aggregate
The modified recycled coarse aggregate preparation example 5 is different from the modified recycled coarse aggregate preparation example 3 only in that: the recycled coarse aggregate in the modified recycled coarse aggregate preparation example 5 is different in grading, and the recycled coarse aggregate in the modified recycled coarse aggregate preparation example 5 is continuously graded by 4.75-25mm, wherein 15% of the recycled coarse aggregate with the particle size of 4.75-9.5mm, 25% of the recycled coarse aggregate with the particle size of 9.5-16mm, 30% of the recycled coarse aggregate with the particle size of 16-19mm and 30% of the recycled coarse aggregate with the particle size of 19-25mm are adopted.
Comparative preparation example 1 of modified recycled coarse aggregate
The comparative modified recycled coarse aggregate 1 was prepared as follows:
adding 300g of metakaolin, 200g of cement and 800g of water, and fully and uniformly stirring to obtain modified slurry;
9166g of recycled coarse aggregate and the modified slurry are uniformly stirred, and are cured and air-dried under natural conditions to prepare the comparative modified recycled coarse aggregate 1.
Comparative preparation example 2 of modified recycled coarse aggregate
The comparative modified recycled coarse aggregate 2 was prepared as follows:
pouring 100g of sodium silicate and 160g of sodium hydroxide into 800g of water, uniformly stirring, standing and aging for 3h, adding 200g of cement, and fully and uniformly stirring to obtain modified slurry;
8884g of the recycled coarse aggregate and the modified slurry are uniformly stirred, and are cured and air-dried under natural conditions to prepare a comparative modified recycled coarse aggregate 2.
Examples of preparation of modified recycled Fine aggregate
In modified recycled fine aggregate preparation examples 1 to 3, 0.15 to 4.75mm continuous gradation was adopted for the recycled fine aggregate, wherein 21.4% of the recycled fine aggregate having a particle size of 0.15 to 0.3mm, 25.9% of the recycled fine aggregate having a particle size of 0.3 to 0.6mm, 28.4% of the recycled fine aggregate having a particle size of 0.6 to 1.18mm, 15.8% of the recycled fine aggregate having a particle size of 1.18 to 2.36mm, and 8.5% of the recycled fine aggregate having a particle size of 2.36 to 4.75 mm.
Preparation example 1 of modified recycled Fine aggregate
The modified recycled fine aggregate 1 was prepared as follows:
uniformly mixing 60g of cement and 10g of fly ash, then adding 80g of water, and uniformly stirring to obtain a cement soak solution;
soaking 750g of recycled fine aggregate in a cement soak solution, stirring once every 20min, and stopping soaking until cement slurry is coagulated on the surface of the recycled fine aggregate;
and after soaking, filtering by using a 5mm square-hole sieve, keeping the sieve on the 5mm square-hole sieve for 10min, shaking the sieve once every 5min, and curing and air-drying all undersize under natural conditions to obtain the modified recycled fine aggregate 1.
Preparation example 2 of modified recycled Fine aggregate
The modified recycled fine aggregate 2 was prepared as follows:
uniformly mixing 100g of cement and 20g of fly ash, then adding 150g of water, and uniformly stirring to obtain a cement soak solution;
1350g of recycled fine aggregate is soaked in the cement soak solution, and the soaking is stopped when cement slurry is coagulated on the surface of the recycled fine aggregate after stirring every 30 min;
and after soaking, filtering by using a 5mm square-hole sieve, keeping the sieve on the 5mm square-hole sieve for 20min, shaking the sieve once every 3min, and curing and air-drying all undersize under natural conditions to obtain the modified recycled fine aggregate 2.
Preparation example 3 of modified recycled Fine aggregate
The modified recycled fine aggregate 3 was prepared as follows:
uniformly mixing 80g of cement and 10g of fly ash, then adding 90g of water, and uniformly stirring to obtain a cement soak solution;
soaking 900g of the recycled fine aggregate in a cement soak solution, stirring once every 25min, and stopping soaking until cement paste is coagulated on the surface of the recycled fine aggregate;
and after soaking, filtering by using a 5mm square-hole sieve, keeping the sieve on the 5mm square-hole sieve for 20min, shaking the sieve once every 5min, and curing and air-drying all undersize under natural conditions to obtain the modified recycled fine aggregate 3.
Preparation example 4 of modified recycled Fine aggregate
The modified recycled fine aggregate preparation example 4 is different from the modified recycled fine aggregate preparation example 3 only in that: the recycled fine aggregate in modified recycled fine aggregate preparation example 4 is different in gradation, and the recycled fine aggregate in modified recycled fine aggregate preparation example 4 is 0.15-4.75mm continuous gradation, wherein 10% of the recycled fine aggregate with a particle size of 0.15-0.3mm, 30% of the recycled fine aggregate with a particle size of 0.3-0.6mm, 30% of the recycled fine aggregate with a particle size of 0.6-1.18mm, 10% of the recycled fine aggregate with a particle size of 1.18-2.36mm, and 20% of the recycled fine aggregate with a particle size of 2.36-4.75 mm.
Examples
The DPS waterproof agent is DPS waterproof emulsion, and the content of effective substances of the DPS waterproof emulsion is 77.3 percent;
the water reducing agent is naphthalene sulfonate water reducing agent.
Example 1
The C30 recycled aggregate concrete is prepared as follows:
prewetting 7kg of modified recycled coarse aggregate 1 with water, and then uniformly stirring with 4kg of cement, 2.3kg of fly ash and 2kg of natural river sand to obtain a dry mixture;
adding 0.1kg of water reducing agent and 0.5kg of DPS waterproof emulsion into 3.15kg of water, and uniformly stirring to obtain a mixed solution;
and mixing the dry mixture and the mixed solution, and uniformly stirring to obtain the recycled aggregate concrete.
Example 2
A C30 recycled aggregate concrete is prepared as follows:
pre-wetting 9kg of modified recycled coarse aggregate 1 with water, and then uniformly stirring with 5kg of cement, 1kg of fly ash and 3kg of natural river sand to obtain a dry mixture;
adding 0.5kg of water reducing agent and 0.1kg of DPS waterproof emulsion into 3kg of water, and uniformly stirring to obtain a mixed solution;
and mixing the dry mixture and the mixed solution, and uniformly stirring to obtain the recycled aggregate concrete.
Example 3
A C30 recycled aggregate concrete is prepared as follows:
pre-wetting 8kg of modified recycled coarse aggregate 1 with water, and then uniformly stirring with 4.5kg of cement, 1.5kg of fly ash and 2kg of natural river sand to obtain a dry mixture;
adding 0.3kg of water reducing agent and 0.2kg of DPS waterproof emulsion into 3kg of water, and uniformly stirring to obtain a mixed solution;
and mixing the dry mixture and the mixed solution, and uniformly stirring to obtain the recycled aggregate concrete.
Example 4
A C30 recycled aggregate concrete is prepared as follows:
pre-wetting 8kg of modified recycled coarse aggregate 1 with water, and then uniformly stirring with 4.5kg of cement, 1.5kg of fly ash and 2kg of natural river sand to obtain a dry mixture;
adding 0.3kg of water reducing agent and 0.2kg of DPS waterproof emulsion into 2.94kg of water, and uniformly stirring to obtain a mixed solution;
and mixing the dry mixture and the mixed solution, and uniformly stirring to obtain the recycled aggregate concrete.
Example 5
The C30 recycled aggregate concrete is prepared as follows:
pre-wetting 8kg of modified recycled coarse aggregate 1 with water, and then uniformly stirring with 4.5kg of cement, 1.5kg of fly ash and 2kg of natural river sand to obtain a dry mixture;
adding 0.3kg of water reducing agent and 0.2kg of DPS waterproof emulsion into 3.3kg of water, and uniformly stirring to obtain a mixed solution;
and mixing the dry mixture and the mixed solution, and uniformly stirring to obtain the recycled aggregate concrete.
Example 6
A C30 recycled aggregate concrete is prepared as follows:
pre-wetting 8kg of modified recycled coarse aggregate 1 with water, and then uniformly stirring with 4.5kg of cement, 1.5kg of fly ash and 2kg of modified recycled fine aggregate 1 to obtain a dry mixture;
adding 0.3kg of water reducing agent and 0.2kg of DPS waterproof emulsion into 3kg of water, and uniformly stirring to obtain a mixed solution;
and mixing the dry mixture and the mixed solution, and uniformly stirring to obtain the recycled aggregate concrete.
Example 7
A C30 recycled aggregate concrete is prepared as follows:
pre-wetting 8kg of modified recycled coarse aggregate 1 with water, and then uniformly stirring with 4.5kg of cement, 1.5kg of fly ash, 1kg of natural river sand and 1kg of modified recycled fine aggregate 1 to obtain a dry mixture;
adding 0.3kg of water reducing agent and 0.2kg of DPS waterproof emulsion into 3kg of water, and uniformly stirring to obtain a mixed solution;
and mixing the dry mixture and the mixed solution, and uniformly stirring to obtain the recycled aggregate concrete.
Example 8
A C30 recycled aggregate concrete is prepared as follows:
pre-wetting 8kg of modified recycled coarse aggregate 1 with water, and then uniformly stirring with 4.5kg of cement, 1.5kg of fly ash and 2kg of natural river sand to obtain a dry mixture;
adding 0.3kg of water reducing agent and 0.2kg of anti-crack fiber into 3kg of water, and uniformly stirring to obtain a mixed solution;
and mixing the dry mixture and the mixed solution, and uniformly stirring to obtain the recycled aggregate concrete.
Example 9
A C30 recycled aggregate concrete is prepared as follows:
prewetting 8kg of modified recycled coarse aggregate 1 with water, and then uniformly stirring with 4.5kg of cement, 1.5kg of fly ash and 2kg of natural river sand to obtain a dry mixture;
adding 0.3kg of water reducing agent, 0.1kg of DPS waterproof emulsion and 0.1kg of anti-crack fiber into 3kg of water, and uniformly stirring to obtain a mixed solution;
and mixing the dry mixture and the mixed solution, and uniformly stirring to obtain the recycled aggregate concrete.
Examples 10 to 13
Examples 10-13 differ from example 6 only in that: the modified recycled coarse aggregates used in examples 10 to 13 were different from each other, and the rest was the same as in example 6.
The modified recycled coarse aggregate in examples 10 to 13 is specifically shown in Table 1 below.
TABLE 1
Examples Modified recycled coarse aggregate
Example 6 Modified recycled coarse aggregate 1
Example 10 Modified recycled coarse aggregate 2
Example 11 Modified recycled coarse aggregate 3
Example 12 Modified recycled coarse aggregate 4
Example 13 Modified recycled coarse aggregate 5
Examples 14 to 16
Examples 14-16 differ from example 11 only in that: the modified recycled fine aggregate used in examples 14 to 16 was different from that used in example 11.
The modified recycled fine aggregate of examples 14 to 16 is specifically shown in Table 2 below.
TABLE 2
Examples Modified recycled fine aggregate
Example 11 Modified recycled Fine aggregate 1
Example 14 Modified recycled fine aggregate 2
Example 15 Modified recycled fine aggregate 3
Example 16 Modified recycled fine aggregate 4
Comparative example
Comparative example 1
Comparative example 1 differs from example 6 only in that: in comparative example 1, the modified recycled coarse aggregate 1 was replaced with the comparative modified recycled coarse aggregate 1 in an equal amount, and the rest was in accordance with example 6.
Comparative example 2
Comparative example 2 differs from example 6 only in that: in comparative example 2, the modified recycled coarse aggregate 1 was replaced with the comparative modified recycled coarse aggregate 2 in an equal amount, and the rest was in accordance with example 6.
Comparative example 3
Comparative example 3 differs from example 6 only in that: in comparative example 3, the modified recycled coarse aggregate 1 was replaced with the recycled coarse aggregate in equal amount, and the rest was the same as in example 6.
Comparative example 4
Comparative example 4 differs from example 6 only in that: in comparative example 4, the modified recycled coarse aggregate 1 was replaced with the same amount of crushed natural stone of the same composition, and the rest was the same as in example 6.
Comparative example 5
Comparative example 5 differs from example 6 only in that: the modified recycled coarse aggregate 1 in comparative example 5 was 9kg, the modified recycled fine aggregate was 1kg, and the rest was the same as in example 6.
Performance test
The basic performances of the recycled coarse aggregate, the modified recycled coarse aggregate 1-5 and the comparative modified recycled coarse aggregate 1-2 were measured, and the specific measurement results are shown in table 3 below.
TABLE 3
Sample(s) Apparent density kg/m3 Void fraction/%) Water absorption/%)
Natural coarse aggregate 2720 10 1.80
Recycled coarse aggregate 2450 4.2 6.08
Modified recycled coarse aggregate 1 2600 7.6 3.20
Modified recycled coarse aggregate 2 2608 7.8 3.24
Modified recycled coarse aggregate 3 2624 8.2 3.08
Modified recycled coarse aggregate 4 2615 8.0 3.13
Modified recycled coarse aggregate 5 2475 6.0 3.78
Comparative modified recycled coarse aggregate 1 2490 7.0 3.45
Comparative modified recycled coarse aggregate 2 2510 6.4 3.32
It can be seen from the above table 3 that the modified slurry obtained by mixing cement, metakaolin, sodium silicate, sodium hydroxide and water in a formula ratio can improve the apparent density and porosity of the recycled coarse aggregate and reduce the water absorption rate of the recycled coarse aggregate when the coarse aggregate concrete is modified by the modified slurry.
The mechanical properties of the recycled aggregate concrete prepared in examples 1 to 16 and comparative examples 1 to 5 were measured, and the specific measurement results are shown in small table 4.
TABLE 4
Recycled aggregate concrete 28 day compressive strength/MPa
Example 1 32.2
Example 2 32.6
Example 3 33.7
Example 4 33.0
Example 5 32.8
Example 6 33.2
Example 7 33.4
Example 8 33.0
Example 9 33.3
Example 10 33.4
Example 11 33.9
Example 12 33.6
Example 13 32.0
Example 14 33.7
Example 15 34.4
Example 16 32.1
Comparative example 1 28.5
Comparative example 2 29.4
Comparative example 3 20.2
Comparative example 4 34.5
Comparative example 5 31.4
It can be seen from a combination of examples 3-5 and table 4 that the water-to-gel ratio affects the strength of the recycled concrete under the remaining conditions.
Combining examples 3 and 6, 7 and table 4, it can be seen that, under the same remaining conditions, the selection of natural river sand as the fine aggregate in the recycled concrete and/or the modified recycled fine aggregate of the present application has little effect on the strength of the recycled concrete of the present application; in order to reduce the exploitation of natural river sand and improve the utilization rate of waste concrete, in actual construction, the natural river sand can be replaced by modified regenerated fine aggregate.
It can be seen from the combination of examples 6, 10 to 13 and comparative examples 1 to 4 and from Table 4 that the properties of the modified recycled coarse aggregate have a great influence on the strength of recycled concrete. Specifically, the method comprises the following steps: comparative example 6 and comparative examples 3 and 4 show that: the recycled coarse aggregate is directly used without modification treatment, so that the strength of the obtained concrete is poor, and the strength of the recycled concrete can be greatly improved by using the modified recycled coarse aggregate; even if the modified recycled coarse aggregate is used for replacing the natural macadam in percentage, the influence on the strength of the recycled concrete is small, and the use is hardly influenced; as can be seen from comparative example 6 and comparative examples 1 to 2, the following compositions were used in the present application in the mass ratios of (7 to 12): (10-17): (3-6): (5-9): (35-50) the cement, the metakaolin, the sodium silicate and the sodium hydroxide and the prepared modified slurry modify the recycled coarse aggregate, so that the strength of the recycled concrete can be improved; it is understood from comparative examples 6 and 13 that the ratio of the particle size of the modified recycled coarse aggregate also affects the strength of the recycled concrete.
The present embodiment is only for explaining the present application, and it is not limited to the present application, and those skilled in the art can make modifications of the present embodiment without inventive contribution as needed after reading the present specification, but all of them are protected by patent law within the scope of the claims of the present application.

Claims (10)

1. A C30 recycled aggregate concrete is characterized in that: the feed comprises the following raw materials in parts by weight:
40-50 parts of cement, 10-23 parts of fly ash, 20-30 parts of fine aggregate, 70-90 parts of modified recycled coarse aggregate, 1-5 parts of water reducing agent, 1-5 parts of auxiliary agent and water, wherein the water-to-glue ratio is 0.49-0.55;
the modified recycled coarse aggregate is prepared by soaking and modifying recycled coarse aggregate by modified slurry; the modified slurry comprises cement, metakaolin, sodium silicate, sodium hydroxide and water, wherein the mass ratio of the cement to the metakaolin to the sodium silicate to the sodium hydroxide to the water is (7-12): (10-17): (3-6): (5-9): (35-50).
2. The C30 recycled aggregate concrete according to claim 1, wherein: the mass ratio of the cement to the metakaolin to the sodium silicate to the sodium hydroxide to the water is (7-10): (12-17): (5-6): (7-9): (35-42).
3. The C30 recycled aggregate concrete according to claim 1 or 2, wherein: the recycled coarse aggregate adopts 4.75-31.5mm continuous gradation, wherein 20-25% of the recycled coarse aggregate with the particle size of 4.75-9.5mm, 32-36% of the recycled coarse aggregate with the particle size of 9.5-16mm, 10-15% of the recycled coarse aggregate with the particle size of 16-19mm, 21-27% of the recycled coarse aggregate with the particle size of 19-26.5mm and 0.2-0.8% of the recycled coarse aggregate with the particle size of 26.5-31.5 mm.
4. The C30 recycled aggregate concrete according to claim 1, wherein: the fine aggregate is at least one selected from modified recycled fine aggregate and natural river sand.
5. The C30 recycled aggregate concrete according to claim 4, wherein: the modified recycled fine aggregate is prepared by soaking recycled fine aggregate in a cement soaking solution, wherein the cement soaking solution comprises cement, fly ash and water.
6. The C30 recycled aggregate concrete according to claim 5, wherein: the mass ratio of the cement to the fly ash to the water is (6-10): (1-2): (8-15).
7. The C30 recycled aggregate concrete according to claim 1 or 4, wherein: the recycled fine aggregate is 0.15-4.75mm continuous gradation, wherein 18-22% of the recycled fine aggregate with the particle size of 0.15-0.3mm, 23-27.3% of the recycled fine aggregate with the particle size of 0.3-0.6mm, 26-30% of the recycled fine aggregate with the particle size of 0.6-1.18mm, 10-16% of the recycled fine aggregate with the particle size of 1.18-2.36mm and 5-10% of the recycled fine aggregate with the particle size of 2.36-4.75 mm.
8. The C30 recycled aggregate concrete of claim 1, wherein: the auxiliary agent is selected from at least one of DPS waterproofing agent and crack resistance agent.
9. The method for preparing C30 recycled aggregate concrete according to any one of claims 1 to 8, wherein: the method comprises the following steps:
pre-wetting the modified recycled coarse aggregate with water, and then uniformly stirring the pre-wetted modified recycled coarse aggregate with cement, fly ash and fine aggregate to obtain a dry blend;
adding a water reducing agent and an auxiliary agent into water, and uniformly stirring to obtain a mixed solution;
and mixing the dry mixture and the mixed solution, and uniformly stirring to obtain the recycled aggregate concrete.
10. The method for preparing C30 recycled aggregate concrete according to claim 9, wherein: the preparation method of the modified recycled coarse aggregate comprises the following steps:
according to the formula proportion, sodium silicate and sodium hydroxide are poured into water and stirred uniformly, then the mixture is kept stand and aged for 2-4 hours, and metakaolin and cement are added and stirred uniformly to obtain modified slurry;
and uniformly stirring the recycled coarse aggregate and the modified slurry, and curing and air-drying under natural conditions to obtain the modified recycled coarse aggregate.
CN202211065050.9A 2022-09-01 2022-09-01 C30 recycled aggregate concrete and preparation method thereof Pending CN115490464A (en)

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CN113087427A (en) * 2021-03-12 2021-07-09 中国地质大学（武汉） Recycled aggregate soaked based on metakaolin slurry and modification method thereof
CN114455911A (en) * 2022-02-11 2022-05-10 西安高科新达混凝土有限责任公司 Regenerated fine aggregate concrete and preparation method thereof

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CN113087427A (en) * 2021-03-12 2021-07-09 中国地质大学（武汉） Recycled aggregate soaked based on metakaolin slurry and modification method thereof
CN114455911A (en) * 2022-02-11 2022-05-10 西安高科新达混凝土有限责任公司 Regenerated fine aggregate concrete and preparation method thereof

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