Durable recycled concrete preparation process

Abstract

The invention discloses a preparation process of durable recycled concrete. The preparation process of the durable recycled concrete comprises the following steps: S1, pretreating recycled aggregate; s2, dry mixing of the raw materials; s3, adding water and stirring; the step S1 comprises the following steps: washing and mechanically screening the recycled aggregate, and then screening the recycled aggregate into recycled coarse aggregate with a preset particle size and recycled fine aggregate with a preset particle size; in the step S1, the recycled aggregate is alternately cleaned through a high-pressure water washing technology and an ultrasonic cleaning technology, so that roughening of the surface of the recycled aggregate is completed while the recycled aggregate is cleaned; and detecting and calculating the water-soluble sulfate content of the recycled aggregate subjected to ultrasonic cleaning every time until the water-soluble sulfate content in the recycled aggregate is less than 0.2% by weight, and finishing cleaning of the recycled aggregate. The durable recycled concrete is prepared by roughening the surface of the recycled aggregate, so that the bonding force between cement paste and the recycled aggregate can be enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of concrete, and in particular to a process for preparing durable recycled concrete. Background Art

[0002] Recycled concrete refers to concrete that uses recycled aggregates (usually from the recycling of waste concrete structures) to replace natural aggregates and has high durability. This type of concrete combines the advantages of environmental sustainability and long-term performance, and its durability is usually achieved by enhancing impermeability, freeze-thaw resistance, corrosion resistance and other properties. Recycled concrete reduces dependence on natural resources, reduces the treatment and accumulation of construction waste, and reduces the burden on the environment by using recycled aggregates. To ensure that recycled concrete has sufficient durability, specific admixtures (such as mineral powder, fly ash, etc.) are usually added to the concrete mix to improve the microstructure and performance of concrete, so that it can better resist the influence of environmental factors (such as water, freeze-thaw cycles, chemical corrosion, etc.). As for the economic efficiency of recycled concrete, recycled aggregates are usually cheaper than natural aggregates, so they can reduce construction costs. It is especially suitable for large-scale or low-cost construction projects such as road construction, infrastructure repair and new construction.

[0003] However, during the preparation process of existing recycled concrete, due to the instability of the quality of recycled aggregates, it may still contain a large amount of impurities, and the adhesion between aggregates and cement is insufficient, resulting in poor durability of the existing recycled concrete. Summary of the invention

[0004] Based on this, it is necessary to provide a durable recycled concrete preparation process to address the technical problem of insufficient durability of existing recycled concrete.

[0005] A durable recycled concrete preparation process comprises the following steps: S1, recycled aggregate pretreatment; S2, raw material dry mixing; S3, adding water and stirring.

[0006] The above-mentioned step S1 includes the following steps: washing and mechanically screening the recycled aggregate to remove impurities in the recycled aggregate, and roughening the surface of the recycled aggregate to increase its adhesion with cement slurry, and then screening the recycled aggregate into recycled coarse aggregate of a preset particle size and recycled fine aggregate of a preset particle size.

[0007] In the above-mentioned step S1, the recycled aggregate is alternately cleaned by high-pressure water washing technology and ultrasonic cleaning technology, so that the surface of the recycled aggregate is roughened while the recycled aggregate is cleaned; the water-soluble sulfate content of the recycled aggregate after each ultrasonic cleaning is detected and calculated until the water-soluble sulfate content in the recycled aggregate is less than 0.2% by weight, the cleaning of the recycled aggregate is terminated, and then subsequent screening work is carried out to obtain recycled coarse aggregate and recycled fine aggregate of preset particle size.

[0008] In one embodiment, the above step S2 includes the following steps: mixing the dried recycled coarse aggregate, recycled fine aggregate, natural aggregate, fly ash and cement in a preset proportion to obtain a dry mix, ensuring that each material is evenly distributed in the mixture.

[0009] In one embodiment, the above-mentioned step S3 also includes the following steps: gradually adding water and admixtures to the dry mix, and fully stirring with a strong stirring device at a preset stirring speed and stirring time, wherein water is added in batches to prevent uneven distribution of water in the mixture, thereby improving the cement hydration effect and the strength of the concrete.

[0010] In one of the embodiments, the above-mentioned durable recycled concrete preparation process also includes step S4: selecting a corresponding mold according to the purpose of the concrete product, introducing the evenly mixed concrete into the mold, and using a vibrator to compact it to ensure that there are no bubbles and air in the concrete; wet curing is carried out by spraying, the curing temperature is controlled at 20-25°C, and the humidity is maintained at more than 90%, and the curing time is more than 28 days to ensure that the cement is fully hydrated.

[0011] In one embodiment, in the above step S1, the particle size of the recycled coarse aggregate is set to 5-20 mm, and the particle size of the recycled fine aggregate is set to less than 5 mm.

[0012] In one of the embodiments, in the above step S2, the component ratio of the dry mix is ​​set to: 360 parts of recycled coarse aggregate, 180 parts of recycled fine aggregate, 540-1200 parts of natural aggregate, 270-600 parts of sand, 130-150 parts of cement and 30 parts of fly ash.

[0013] In one embodiment, the dry mixture in the above step S2 also includes 15 parts of mineral powder and 8 parts of silica fume.

[0014] In one embodiment, the stirring time in the above step S2 is 3-5 minutes to ensure that all components are fully mixed.

[0015] In one embodiment, in the above step S3, water is added to the dry mix in batches at a water-to-cement ratio of 0.5.

[0016] In one embodiment, the admixture includes 3 parts of a water reducing agent and 0.3 parts of an air entraining agent.

[0017] In one of the embodiments, in the above step S3, a forced mixer is used to fully stir the concrete during the water adding and stirring process, and the stirring time is set to 3-5 minutes to ensure that the concrete is evenly mixed and the cement slurry is fully combined with the aggregate.

[0018] In one of the embodiments, the above-mentioned durable recycled concrete preparation process also includes step S5: obtaining a standard specimen based on the casting of the durable recycled concrete, and conducting performance tests such as compressive strength, flexural strength, frost resistance, impermeability, and chemical corrosion resistance, and at the same time conducting long-term and regular inspections on the standard specimen to ensure that the standard specimen has no cracks, falling off or other cracking phenomena.

[0019] The above-mentioned durable recycled concrete preparation process alternately cleans the recycled aggregate by high-pressure water washing technology and ultrasonic cleaning technology, thereby completing the roughening of the surface of the recycled aggregate while cleaning the recycled aggregate; the water-soluble sulfate content of the recycled aggregate after each ultrasonic cleaning is detected and calculated, until the water-soluble sulfate content in the recycled aggregate is less than 0.2% by weight, the recycled aggregate cleaning is terminated, and then subsequent screening work is performed to obtain recycled coarse aggregate and recycled fine aggregate of a preset particle size. Based on this, the durable recycled concrete preparation of the present invention can effectively remove most of the impurities such as soil, oil, wood and plastic in the recycled aggregate by high-intensity water washing of the recycled aggregate, thereby avoiding the impurities in the recycled aggregate from adversely affecting the bonding strength between the cement slurry and the aggregate, resulting in a decrease in the durability of the concrete. At the same time, by roughening the surface of the recycled aggregate, the bonding force between the cement slurry and the recycled aggregate can be enhanced, and the risk of the recycled aggregate falling off at the cement slurry interface can be reduced, thereby improving the crack resistance and durability of the concrete. DETAILED DESCRIPTION

[0020] In order to make the above-mentioned purpose, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below. In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed below.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like indicating the orientation or position relationship are based on the orientation or position relationship shown, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0022] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0023] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0024] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0025] It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are for illustrative purposes only and are not intended to be the only implementation method.

[0026] The present invention discloses a durable recycled concrete preparation process, which comprises the following steps: S1, pretreatment of recycled aggregate; S2, dry mixing of raw materials; S3, stirring with water. The above step S1 comprises the following steps: washing and mechanically screening the recycled aggregate to remove impurities in the recycled aggregate, and roughening the surface of the recycled aggregate to increase its bonding force with cement slurry, and then screening the recycled aggregate into recycled coarse aggregate with a preset particle size and recycled fine aggregate with a preset particle size. The above step S2 comprises the following steps: mixing the dried recycled coarse aggregate, recycled fine aggregate, natural aggregate, fly ash and cement in a preset proportion to obtain a dry mix, ensuring that each material is evenly distributed in the mixture. The above step S3 also comprises the following steps: gradually adding water and admixtures to the dry mix, and fully stirring with a strong stirring device at a preset stirring speed and stirring time, wherein water is added in batches to prevent uneven distribution of water in the mixture, thereby improving the cement hydration effect and the strength of the concrete. Specifically, in the above step S1, the recycled aggregate is alternately cleaned by high-pressure water washing technology and ultrasonic cleaning technology, so that the surface of the recycled aggregate is roughened while the recycled aggregate is cleaned; the water-soluble sulfate content of the recycled aggregate after each ultrasonic cleaning is detected and calculated, until the water-soluble sulfate content in the recycled aggregate is less than 0.2% by weight, the recycled aggregate cleaning is terminated, and then subsequent screening is performed to obtain recycled coarse aggregate and recycled fine aggregate of a preset particle size. Based on this, the durable recycled concrete preparation of the present invention can effectively remove most of the impurities such as soil, oil, wood and plastic in the recycled aggregate by high-intensity water washing of the recycled aggregate, thereby avoiding the impurities in the recycled aggregate from adversely affecting the bonding strength between the cement slurry and the aggregate, resulting in a decrease in the durability of the concrete. At the same time, by roughening the surface of the recycled aggregate, the bonding force between the cement slurry and the recycled aggregate can be enhanced, and the risk of the recycled aggregate falling off at the cement slurry interface can be reduced, thereby improving the crack resistance and durability of the concrete.

[0027] Furthermore, the durable recycled concrete preparation process also includes step S4: selecting a corresponding mold according to the purpose of the concrete product, introducing the evenly mixed concrete into the mold, and using a vibrator to compact the concrete to ensure that there are no bubbles and air in the concrete; wet curing is carried out by spraying, the curing temperature is controlled at 20-25°C, and the humidity is maintained at more than 90%, and the curing time is more than 28 days to ensure that the cement is fully hydrated.

[0028] Furthermore, in the above step S1, the particle size of the recycled coarse aggregate is set to 5-20 mm, and the particle size of the recycled fine aggregate is set to less than 5 mm.

[0029] Furthermore, in the above step S2, the component ratio of the dry mix is ​​set to: 360 parts of recycled coarse aggregate, 180 parts of recycled fine aggregate, 540-1200 parts of natural aggregate, 270-600 parts of sand, 130-150 parts of cement and 30 parts of fly ash. In one embodiment, the dry mix in the above step S2 also includes 15 parts of mineral powder and 8 parts of silica fume. In this embodiment, the addition of fly ash, mineral powder and silica fume can effectively improve the compactness of concrete, reduce the amount of cement, and have a beneficial effect on cement hydration, enhancing impermeability, freeze-thaw resistance and chemical corrosion resistance. In another embodiment, the stirring time in step S2 is 3-5 minutes to ensure that the components are fully mixed.

[0030] Furthermore, in the above step S3, water is added to the dry mix in batches at a water-cement ratio of 0.5. In one embodiment, the admixture includes 3 parts of a water reducer and 0.3 parts of an air entraining agent, wherein the use of a high-efficiency water reducer can effectively reduce the water-cement ratio, thereby enhancing the compactness of the concrete while ensuring workability, thereby improving the durability of the concrete; reducing the water-cement ratio helps to reduce the capillary structure and improve water permeability resistance; the air entraining agent can increase the microscopic pores of the concrete, making it have better freeze-thaw resistance, and is particularly suitable for applications under cold climate conditions.

[0031] Furthermore, in the above step S3, a forced mixer is used to fully stir the concrete during the water adding and stirring process, and the stirring time is set to 3-5 minutes to ensure that the concrete is evenly mixed and the cement slurry is fully combined with the aggregate.

[0032] Furthermore, the durable recycled concrete preparation process also includes step S5: obtaining standard specimens based on the casting of durable recycled concrete, and conducting performance tests such as compressive strength, flexural strength, frost resistance, impermeability, and chemical corrosion resistance, and at the same time conducting long-term and regular inspections on the standard specimens to ensure that the standard specimens have no cracks, falling off, or other cracking phenomena.

[0033] In summary, the durable recycled concrete preparation process disclosed by the present invention alternately cleans the recycled aggregate through high-pressure water washing technology and ultrasonic cleaning technology, thereby completing the roughening of the surface of the recycled aggregate while cleaning the recycled aggregate; the water-soluble sulfate content of the recycled aggregate after each ultrasonic cleaning is detected and calculated, until the water-soluble sulfate content in the recycled aggregate is less than 0.2% by weight, the recycled aggregate cleaning is terminated, and then subsequent screening work is performed to obtain recycled coarse aggregate and recycled fine aggregate of a preset particle size. Based on this, the durable recycled concrete preparation of the present invention can effectively remove most of the impurities such as soil, oil, wood and plastic in the recycled aggregate by high-intensity water washing of the recycled aggregate, thereby avoiding the impurities in the recycled aggregate from adversely affecting the bonding strength between the cement slurry and the aggregate, resulting in a decrease in the durability of the concrete. At the same time, by roughening the surface of the recycled aggregate, the bonding force between the cement slurry and the recycled aggregate can be enhanced, and the risk of the recycled aggregate falling off at the cement slurry interface can be reduced, thereby improving the crack resistance and durability of the concrete.

[0034] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0035] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A process for preparing durable recycled concrete, characterized in that: The method comprises the following steps: S1, pre-treating recycled aggregate; S2, dry mixing raw materials; S3, adding water and stirring; The above-mentioned step S1 comprises the following steps: washing and mechanically screening the recycled aggregate to remove impurities in the recycled aggregate, and roughening the surface of the recycled aggregate to increase its bonding force with cement slurry, and then screening the recycled aggregate into recycled coarse aggregate of a preset particle size and recycled fine aggregate of a preset particle size; In the above-mentioned step S1, the recycled aggregate is alternately cleaned by high-pressure water washing technology and ultrasonic cleaning technology, so that the surface of the recycled aggregate is roughened while the recycled aggregate is cleaned; the water-soluble sulfate content of the recycled aggregate after each ultrasonic cleaning is detected and calculated until the water-soluble sulfate content in the recycled aggregate is less than 0.2% by weight, the cleaning of the recycled aggregate is terminated, and then subsequent screening work is carried out to obtain recycled coarse aggregate and recycled fine aggregate of preset particle size.

2. The process for preparing durable recycled concrete according to claim 1, characterized in that: The above-mentioned step S2 comprises the following steps: mixing the dried recycled coarse aggregate, recycled fine aggregate, natural aggregate, fly ash and cement evenly in a preset proportion to obtain a dry mix, ensuring that each material is evenly distributed in the mixture.

3. The process for preparing durable recycled concrete according to claim 2, characterized in that: The above-mentioned step S3 also includes the following steps: gradually adding water and admixtures to the dry mix, and fully stirring with a strong stirring device at a preset stirring speed and stirring time, wherein water is added in batches to prevent uneven distribution of water in the mixture, thereby improving the cement hydration effect and the strength of the concrete.

4. The process for preparing durable recycled concrete according to claim 3, characterized in that: The durable recycled concrete preparation process also includes step S4: selecting a corresponding mold according to the purpose of the concrete product, introducing the evenly mixed concrete into the mold, and using a vibrator to compact the concrete to ensure that there are no bubbles and air in the concrete; wet curing is performed by spraying, the curing temperature is controlled at 20-25°C, and the humidity is maintained at above 90%, and the curing time is more than 28 days to ensure that the cement is fully hydrated.

5. The process for preparing durable recycled concrete according to claim 4, characterized in that: In the above step S1, the particle size of the recycled coarse aggregate is set to 5-20 mm, and the particle size of the recycled fine aggregate is set to less than 5 mm.

6. The process for preparing durable recycled concrete according to claim 5, characterized in that: In the above step S2, the component ratio of the dry mix is ​​set to: 360 parts of recycled coarse aggregate, 180 parts of recycled fine aggregate, 540-1200 parts of natural aggregate, 270-600 parts of sand, 130-150 parts of cement and 30 parts of fly ash.

7. The process for preparing durable recycled concrete according to claim 6, characterized in that: The dry mix in step S2 also includes 15 parts of mineral powder and 8 parts of silica fume.

8. The process for preparing durable recycled concrete according to claim 7, characterized in that: The stirring time in step S2 is 3-5 min to ensure that all components are fully mixed.

9. The process for preparing durable recycled concrete according to claim 8, characterized in that: In the above step S3, water is added to the dry mix in batches at a water-to-cement ratio of 0.

5.

10. The process for preparing durable recycled concrete according to claim 9, characterized in that: In the above step S3, a forced mixer is used to fully stir the concrete during the water adding and stirring process, and the stirring time is set to 3-5 minutes to ensure that the concrete is evenly mixed and the cement paste is fully combined with the aggregate.