A production process of recycled concrete

Abstract

The application provides a production process of recycled concrete, which comprises the following raw materials in parts by weight: cement 35-45 parts, recycled aggregate 120-130 parts, mixed fiber 11-13 parts, river sand 66-70 parts, modified glue powder 16-20 parts, water reducing agent 7-9 parts, water 30-40 parts and bacillus spore liquid 1-3 parts; the mixed fiber comprises basalt fiber, polyformaldehyde fiber and wood fiber in a mass ratio of 1:4-8:2-5; the recycled concrete of the application further improves the performance of the recycled concrete by adding effective components such as the mixed fiber, the modified glue powder and the bacillus spore liquid, solves the problems of large shrinkage rate and poor impermeability of the recycled concrete, improves the crushing index of the recycled aggregate, and further improves the compressive strength of the concrete.

Description

Technical Field

[0001] This invention relates to the field of recycled concrete technology, and particularly to the production process of recycled concrete. Background Technology

[0002] Recycled concrete refers to new concrete made by crushing, washing, and grading waste concrete blocks, mixing them with aggregates in a certain proportion to partially or completely replace natural aggregates such as sand and gravel, and then mixing them with cement and water. Typically, waste concrete blocks are crushed using mechanical force. Due to the significant mechanical force, the surface of the crushed recycled aggregate develops numerous cracks, leading to increased absorption and further increasing the shrinkage rate of the concrete. Simultaneously, the old cement mortar formed on the surface of the recycled aggregate also increases its water absorption. During setting and hardening, the new cement paste loses a large amount of water, resulting in more pores and cracks in the recycled concrete, thus reducing its impermeability. Summary of the Invention

[0003] In view of this, the present invention proposes a production process for recycled concrete to solve the above problems.

[0004] The technical solution of this invention is implemented as follows:

[0005] A type of recycled concrete, by weight, comprises the following raw materials: 35-45 parts cement, 120-130 parts recycled aggregate, 11-13 parts mixed fiber, 66-70 parts river sand, 16-20 parts modified adhesive powder, 7-9 parts water-reducing agent, 30-40 parts water, and 1-3 parts Bacillus spores solution.

[0006] Furthermore, the mixed fibers include basalt fibers, polyoxymethylene fibers, and wood fibers in a mass ratio of 1:4-8:2-5.

[0007] Furthermore, the method for preparing the modified adhesive powder includes the following steps:

[0008] S1: Crush waste tires to obtain 50-70 mesh rubber powder;

[0009] S2: Dry the rubber powder at 130-150℃ for 2-3 hours, add ethylene glycol diglycidyl ether, benzoyl peroxide and aliphatic hydrocarbon wax, heat to 80-90℃ and stir at 300-350rpm for 10-15 minutes.

[0010] Furthermore, the amounts of ethylene glycol diglycidyl ether, benzoyl peroxide, and aliphatic hydrocarbon wax added are 30-40%, 5-10%, and 20-25% of the rubber powder mass, respectively.

[0011] Furthermore, the Bacillus bacterial solution comprises Bacillus subtilis and Bacillus amyloliquefaciens in a mass ratio of 1:2-3, wherein the concentration of the Bacillus subtilis solution is 1-1.5×10⁸ cells / mL, and the concentration of the Bacillus amyloliquefaciens solution is 6-8×10⁸ cells / mL.

[0012] Furthermore, the water-reducing agent is a polycarboxylate water-reducing agent.

[0013] Furthermore, the particle size of the recycled aggregate is 10-15 mm.

[0014] Furthermore, a process for producing recycled concrete includes the following steps:

[0015] A1: Mixed fibers and modified rubber powder are added to a ball mill and ball-milled to obtain component A;

[0016] A2: Mix cement, recycled aggregate, and river sand evenly to obtain component B;

[0017] A3: Mix components A, B and water, add Bacillus thuringiensis solution, and obtain recycled concrete.

[0018] Furthermore, the ball milling is performed by mixing at 200-300 rpm for 20-30 minutes.

[0019] Furthermore, in step A3, the stirring and mixing is carried out at 150-180 rpm for 10-15 minutes, and the Bacillus bacterial solution is added and stirred at 80-100 rpm for 5-8 minutes.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] This invention improves the performance of recycled concrete by adding effective components such as mixed fibers, modified adhesive powder, and Bacillus bacterial solution, addressing issues like high shrinkage and poor impermeability. It also improves the crushing index of recycled aggregates, further enhancing the compressive strength of the concrete. The addition of modified adhesive powder enhances the ductility and impact resistance of the concrete, and the further modified rubber powder exhibits better bonding with the recycled aggregates. The mixed bacterial solution prepared using Bacillus subtilis and Bacillus amyloliquefaciens improves the self-healing effect of the concrete. Combined with a reasonable ratio of mixed fibers, it promotes carbonate precipitation, effectively preventing early cracking. Furthermore, because this invention uses recycled aggregates, the alkaline treatment process can lead to poor mixing when the recycled aggregates are mixed with the other components in the concrete. This invention addresses this by using a mixed fiber composition of basalt fiber, polyoxymethylene fiber, and wood fiber, which promotes better bonding between the other components and the recycled aggregates, thus improving the concrete's performance. Detailed Implementation

[0022] To better understand the technical content of this invention, specific embodiments are provided below to further illustrate the invention.

[0023] Unless otherwise specified, the experimental methods used in the embodiments of this invention are all conventional methods.

[0024] Unless otherwise specified, all materials and reagents used in the embodiments of this invention are commercially available.

[0025] The Bacillus bacterial solution used in the embodiments of the present invention is commercially available.

[0026] The particle size of the recycled aggregate is 10-15mm.

[0027] Example 1

[0028] The modified adhesive powder preparation method consists of the following steps:

[0029] S1: Crush waste tires to obtain 50-mesh rubber powder;

[0030] S2: Dry the rubber powder at 130℃ for 2 hours. Add ethylene glycol diglycidyl ether, benzoyl peroxide and aliphatic hydrocarbon wax according to 30%, 5% and 20% of the rubber powder mass, respectively. Heat to 80℃ and stir at 300 rpm for 10 minutes.

[0031] By weight, the following raw materials are weighed: 35 parts cement, 120 parts recycled aggregate, 11 parts mixed fiber, 66 parts river sand, 16 parts modified adhesive powder, 7 parts polycarboxylate superplasticizer, 30 parts water, and 1 part Bacillus spp. bacterial solution; the mixed fiber consists of basalt fiber, polyoxymethylene fiber, and wood fiber in a mass ratio of 1:4:2; the Bacillus spp. bacterial solution consists of Bacillus subtilis bacterial solution and Bacillus amyloliquefaciens bacterial solution in a mass ratio of 1:2, and the concentration of the Bacillus subtilis bacterial solution is 1×10⁻⁶. 8 cell / mL, the concentration of the Bacillus amyloliquefaciens bacterial solution is 6×10⁻⁶. 8 cell / mL.

[0032] Recycled concrete is prepared by the following steps:

[0033] (1) Mix the mixed fibers and modified rubber powder in a ball mill and mix at 200 rpm for 20 min to obtain component A;

[0034] (2) Mix cement, recycled aggregate and river sand evenly to obtain component B;

[0035] (3) Mix component A, component B and water at 150 rpm for 10 min, add Bacillus bacterial solution and mix at 80 rpm for 5 min to obtain recycled concrete.

[0036] Example 2

[0037] The modified adhesive powder preparation method consists of the following steps:

[0038] S1: Shred waste tires to obtain 70-mesh rubber powder;

[0039] S2: Dry the rubber powder at 150℃ for 3 hours, then add ethylene glycol diglycidyl ether, benzoyl peroxide and aliphatic hydrocarbon wax. The amounts of ethylene glycol diglycidyl ether, benzoyl peroxide and aliphatic hydrocarbon wax added are 40%, 10% and 25% of the mass of the rubber powder, respectively. Heat to 90℃ and stir at 350 rpm for 15 minutes.

[0040] The following raw materials are weighed by weight: 45 parts cement, 130 parts recycled aggregate, 13 parts mixed fiber, 70 parts river sand, 20 parts modified adhesive powder, 9 parts polycarboxylate superplasticizer, 40 parts water, and 3 parts Bacillus subtilis inoculum. The mixed fiber consists of basalt fiber, polyoxymethylene fiber, and wood fiber in a mass ratio of 1:8:5. The Bacillus subtilis inoculum consists of Bacillus subtilis inoculum and Bacillus amyloliquefaciens inoculum in a mass ratio of 1:3, and the concentration of the Bacillus subtilis inoculum is 1.5 × 10⁻⁶. 8 The concentration of the Bacillus amyloliquefaciens bacterial solution was 8 × 10⁻⁶ cells / mL. 8 cell / mL.

[0041] Recycled concrete is prepared by the following steps:

[0042] (1) Mix the mixed fibers and modified rubber powder in a ball mill and mix at 300 rpm for 30 min to obtain component A;

[0043] (2) Mix cement, recycled aggregate and river sand evenly to obtain component B;

[0044] (3) Mix component A, component B and water at 180 rpm for 15 min, add Bacillus spores solution and mix at 100 rpm for 8 min to obtain recycled concrete.

[0045] Example 3

[0046] The modified adhesive powder preparation method consists of the following steps:

[0047] S1: Shred waste tires to obtain 60-mesh rubber powder;

[0048] S2: Dry the rubber powder at 140℃ for 2.5h, add ethylene glycol diglycidyl ether, benzoyl peroxide and aliphatic hydrocarbon wax. The amount of ethylene glycol diglycidyl ether, benzoyl peroxide and aliphatic hydrocarbon wax added is 35%, 8% and 23% of the mass of the rubber powder, respectively. Heat to 85℃ and stir at 330rpm for 13min.

[0049] The following raw materials are weighed by weight: 40 parts cement, 125 parts recycled aggregate, 12 parts mixed fiber, 68 parts river sand, 18 parts modified adhesive powder, 8 parts polycarboxylate superplasticizer, 35 parts water, and 2 parts Bacillus subtilis inoculum. The mixed fiber consists of basalt fiber, polyoxymethylene fiber, and wood fiber in a mass ratio of 1:6:3.5. The Bacillus subtilis inoculum consists of Bacillus subtilis inoculum and Bacillus amyloliquefaciens inoculum in a mass ratio of 1:2.5, and the concentration of the Bacillus subtilis inoculum is 1.3 × 10⁻⁶. 8 The concentration of the *Bacillus amyloliquefaciens* bacterial solution was 7 × 10⁻⁶ cells / mL. 8 cell / mL.

[0050] Recycled concrete is prepared by the following steps:

[0051] (1) Mix the mixed fibers and modified rubber powder in a ball mill and mix at 250 rpm for 25 min to obtain component A;

[0052] (2) Mix cement, recycled aggregate and river sand evenly to obtain component B;

[0053] (3) Mix component A, component B and water at 160 rpm for 13 min, add Bacillus spores solution and mix at 90 rpm for 8 min to obtain recycled concrete.

[0054] Experimental Example 1

[0055] Shrinkage test and chloride ion penetration test were conducted in accordance with standard GBJ82-85 "Test Methods for Long-term Performance and Durability of Ordinary Concrete", and the impermeability grade was evaluated in accordance with GB50108-2008.

[0056]

[0057] Experimental results show that the recycled concrete prepared by this invention has excellent impermeability and reduces concrete shrinkage.

[0058] Comparative Example 1

[0059] Based on Example 3, the composition of the Bacillus bacterial solution was adjusted to use only Bacillus amyloliquefaciens, specifically:

[0060] The modified adhesive powder preparation method consists of the following steps:

[0061] S1: Shred waste tires to obtain 60-mesh rubber powder;

[0062] S2: Dry the rubber powder at 140℃ for 2.5h, add ethylene glycol diglycidyl ether, benzoyl peroxide and aliphatic hydrocarbon wax. The amount of ethylene glycol diglycidyl ether, benzoyl peroxide and aliphatic hydrocarbon wax added is 35%, 8% and 23% of the mass of the rubber powder, respectively. Heat to 85℃ and stir at 330rpm for 13min.

[0063] By weight, weigh the following raw materials: 40 parts cement, 125 parts recycled aggregate, 12 parts mixed fiber, 68 parts river sand, 18 parts modified adhesive powder, 8 parts polycarboxylate superplasticizer, 35 parts water, and 2 parts Bacillus spp. bacterial solution; the mixed fiber consists of basalt fiber, polyoxymethylene fiber, and wood fiber in a mass ratio of 1:6:3.5; the Bacillus spp. bacterial solution has a concentration of 7×10⁻⁶. 8 Bacillus amyloliquefaciens bacterial suspension at cell / mL.

[0064] Recycled concrete is prepared by the following steps:

[0065] (1) Mix the mixed fibers and modified rubber powder in a ball mill and mix at 250 rpm for 25 min to obtain component A;

[0066] (2) Mix cement, recycled aggregate and river sand evenly to obtain component B;

[0067] (3) Mix component A, component B and water at 160 rpm for 13 min, add Bacillus spores solution and mix at 90 rpm for 8 min to obtain recycled concrete.

[0068] The chloride ion diffusion coefficient of the concrete prepared in Comparative Example 1 was tested and found to be 1.8 × 10⁻⁶. -12 m 2 The shrinkage value was 0.046% over 28 days, which was significantly lower than that of the concrete in Example 3. In this invention, Bacillus subtilis and Bacillus amyloliquefaciens were used as a mixed bacterial solution, which has excellent reproductive capacity in the concrete environment, further inducing calcium carbonate deposition, repairing concrete cracks, filling gaps in recycled aggregates, improving the crushing index of recycled aggregates, and increasing the compressive strength of concrete.

[0069] Comparative Example 2

[0070] Based on Example 3, the ratio of the mixed fibers was adjusted, and the mixed fibers consisted of glass fiber, polypropylene fiber, and wood fiber in a mass ratio of 1:1:1. Specifically:

[0071] The modified adhesive powder preparation method consists of the following steps:

[0072] S1: Shred waste tires to obtain 60-mesh rubber powder;

[0073] S2: Dry the rubber powder at 140℃ for 2.5h, add ethylene glycol diglycidyl ether, benzoyl peroxide and aliphatic hydrocarbon wax. The amount of ethylene glycol diglycidyl ether, benzoyl peroxide and aliphatic hydrocarbon wax added is 35%, 8% and 23% of the mass of the rubber powder, respectively. Heat to 85℃ and stir at 330rpm for 13min.

[0074] The following raw materials are weighed by weight: 40 parts cement, 125 parts recycled aggregate, 12 parts mixed fiber, 68 parts river sand, 18 parts modified adhesive powder, 8 parts polycarboxylate superplasticizer, 35 parts water, and 2 parts Bacillus subtilis inoculum. The mixed fiber consists of glass fiber, polypropylene fiber, and wood fiber in a mass ratio of 1:1:1. The Bacillus subtilis inoculum consists of Bacillus subtilis inoculum and Bacillus amyloliquefaciens inoculum in a mass ratio of 1:2.5, and the concentration of the Bacillus subtilis inoculum is 1.3 × 10⁻⁶. 8 The concentration of the *Bacillus amyloliquefaciens* bacterial solution was 7 × 10⁻⁶ cells / mL. 8 cell / mL.

[0075] Recycled concrete is prepared by the following steps:

[0076] (1) Mix the mixed fibers and modified rubber powder in a ball mill and mix at 250 rpm for 25 min to obtain component A;

[0077] (2) Mix cement, recycled aggregate and river sand evenly to obtain component B;

[0078] (3) Mix component A, component B and water at 160 rpm for 13 min, add Bacillus spores solution and mix at 90 rpm for 8 min to obtain recycled concrete.

[0079] The chloride ion diffusion coefficient of the concrete prepared in Comparative Example 2 was tested to be 2.4 × 10⁻⁶. -12 m 2 / s, 28d shrinkage value is 0.053%. The mixed fiber in this invention is composed of a reasonable blend of basalt fiber, polyoxymethylene fiber and wood fiber. The mixed fiber can effectively prevent the initial cracking of concrete. Studies have shown that when fine cracks appear in the concrete in the later stage, due to the addition of Bacillus spore liquid in this invention, the fiber mixture provides more attachment sites, which can promote carbonate precipitation and promote the self-repair effect of concrete cracks.

[0080] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A type of recycled concrete, characterized in that: By weight, it includes the following raw materials: 35-45 parts cement, 120-130 parts recycled aggregate, 11-13 parts mixed fiber, 66-70 parts river sand, 16-20 parts modified rubber powder, 7-9 parts water-reducing agent, 30-40 parts water and 1-3 parts Bacillus thuringiensis bacterial solution; The mixed fibers comprise basalt fiber, polyoxymethylene fiber, and wood fiber in a mass ratio of 1:4-8:2-5; The preparation method of the modified adhesive powder includes the following steps: S1: Shred waste tires to obtain 50-70 mesh rubber powder; S2: Dry the rubber powder at 130-150℃ for 2-3 hours, add ethylene glycol diglycidyl ether, benzoyl peroxide and aliphatic hydrocarbon wax, heat to 80-90℃ and stir at 300-350rpm for 10-15 minutes; The Bacillus bacterial solution comprises Bacillus subtilis and Bacillus amyloliquefaciens in a mass ratio of 1:2-3.

2. The recycled concrete as described in claim 1, characterized in that: In the preparation method of modified rubber powder, the amounts of ethylene glycol diglycidyl ether, benzoyl peroxide and aliphatic hydrocarbon wax added are 30-40%, 5-10% and 20-25% of the mass of rubber powder, respectively.

3. The recycled concrete as described in claim 1, characterized in that: The concentration of the Bacillus subtilis bacterial solution was 1-1.5 × 10⁻⁶. 8 The concentration of the *Bacillus amyloliquefaciens* bacterial solution was 6-8 × 10⁻⁶ cells / mL. 8 cells / mL.

4. The recycled concrete as described in claim 1, characterized in that: The water-reducing agent is a polycarboxylate water-reducing agent.

5. The recycled concrete as described in claim 1, characterized in that: The recycled aggregate has a particle size of 10-15 mm.

6. The production process of recycled concrete according to claim 1, characterized in that: Includes the following steps: A1: Mixed fibers and modified rubber powder are added to a ball mill and ball-milled to obtain component A; A2: Mix cement, recycled aggregate, and river sand evenly to obtain component B; A3: Mix components A, B and water, add Bacillus thuringiensis inoculum, and obtain recycled concrete.

7. The production process of recycled concrete as described in claim 6, characterized in that, The ball milling process involves mixing at 200-300 rpm for 20-30 minutes.

8. The production process of recycled concrete as described in claim 6, characterized in that, In step A3, the stirring and mixing is carried out at 150-180 rpm for 10-15 minutes, and the Bacillus bacterial solution is added and stirred at 80-100 rpm for 5-8 minutes.

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