Microbial enhanced recycled aggregate and preparation method thereof

Abstract

The invention discloses a microbial enhanced recycled aggregate and a preparation method thereof, and relates to the technical field of concrete.The preparation method comprises the following steps that S1, recycled aggregate is prepared; s2, selecting microorganisms; s3, culturing microorganisms; s4, dipping treatment; s5, drying and curing; in the step S1, concrete, bricks, gravels and the like are recycled from the construction waste, and the recycled aggregate with proper particle size (the particle size of the recycled aggregate is 0.15-4.75 mm or 10-20 mm) is obtained through crushing and screening. According to the microorganism enhanced recycled aggregate and the preparation method thereof, maintenance operation needs to be performed step by step in the spraying or soaking process, so that the problems that in the spraying or soaking process, carbon source supply is insufficient, effective fixation is difficult, needed metabolites are generated, and waste of resources, time and space is caused are solved.

Description

Technical Field

[0001] The invention relates to the technical field of concrete, and in particular to a microbial reinforced recycled aggregate and a preparation method thereof. Background Art

[0002] With the acceleration of urbanization worldwide, the construction industry has entered a stage of rapid development. A large number of old buildings have been demolished, resulting in a large amount of construction waste, of which waste concrete accounts for the largest share. Data show that my country dismantles 40 million tons of construction waste each year, of which 34% are concrete blocks, and the resulting waste concrete is 13.6 million tons, and with the acceleration of the pace of economic construction, it is showing an increasing trend. Waste concrete is not only a high-quality concrete aggregate, but also has many advantages in using waste concrete blocks as aggregates. For example, after the disintegration of the building, high-quality crushed and screened concrete blocks and silt can be used as concrete regeneration. Therefore, the use of waste building waste to produce recycled aggregates and prepare recycled concrete is an important development direction for the construction industry in the future. The most valuable way to deal with waste concrete is to reuse it as a renewable resource to produce recycled aggregates and turn waste into treasure.

[0003] For example, the Chinese patent with publication number CN107601941A discloses a method for preparing microbial reinforced recycled aggregate, comprising the following steps: 1) inoculating Bacillus pseudofirmus in a microbial culture medium to obtain a microbial culture solution; 2) mixing the microbial culture solution obtained in step 1) with a mineralized culture solution to obtain a mixed culture solution; 3) soaking the regenerated aggregate in the mixed culture solution obtained in step 2) to obtain reinforced recycled aggregate. The reinforced recycled aggregate prepared by the method for preparing microbial reinforced recycled aggregate of the present invention has a water absorption rate of 4.7-6.1%, and compared with that before microbial treatment, the water absorption rate is reduced by 10.29-21.67%, and the crushing index value is reduced. After the regenerated mortar is prepared from the reinforced recycled aggregate, the compressive strength of the regenerated mortar increases by 5.39-21.84%.

[0004] The existing technology has the following problems:

[0005] In the existing mineralization preparation of recycled aggregates, the curing operation needs to be carried out in steps during the spraying or soaking process, which leads to insufficient carbon source supply during the spraying or soaking process, and it is difficult to effectively fix and produce the required metabolites, resulting in a waste of resources, time and space; at the same time, soaking the unwashed recycled aggregate in the culture medium of microorganisms is not conducive to reducing its water absorption rate and improving the quality of the aggregate; when the recycled aggregate is soaked, dried, etc., the water absorption rate of the recycled aggregate is large due to the pores and cracks generated during the crushing or processing of the recycled aggregate, resulting in a decrease in the performance of the recycled concrete, which restricts the development of the recycled aggregate production recycled concrete field. Summary of the invention

[0006] The present invention provides a microbial reinforced recycled aggregate and a preparation method thereof to solve the problems raised in the above background technology.

[0007] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0008] A microbial reinforced recycled aggregate and a preparation method thereof, comprising the following steps:

[0009] S1. Prepare recycled aggregate;

[0010] S2, select microorganisms;

[0011] S3, culture microorganisms;

[0012] S4, immersion treatment;

[0013] S5. Drying and curing.

[0014] Preferably, in step S1, concrete, bricks, gravel, etc. are recovered from construction waste, and recycled aggregate with appropriate particle size is obtained through crushing and screening (the particle size of the recycled aggregate is 0.15-4.75 mm or 10-20 mm).

[0015] Preferably, in step S2, bacteria that can promote cement hydration reaction (such as Bacillus pseudofirmus and Bacillus pasteurianus, the Bacillus pseudofirmus strain is numbered DSM8715, obtained from the China General Microbiological Culture Collection Administration Center) are selected, and urea-decomposing bacteria are inoculated into a microbial culture medium for cultivation to obtain a microbial culture solution, which is a fungus that can enhance the strength of aggregate.

[0016] Preferably, the culturing in step S3 is carried out under shaking conditions, the shaking frequency is 100-140 rpm; the culturing temperature is 25-37° C., and the culturing time is 10-48 h.

[0017] Preferably, the microbial culture solution obtained in step S3 is mixed with the mineralized culture solution to obtain a mixed culture solution;

[0018] The mass ratio of the recycled aggregate to the mixed culture solution is 1:1 to 1:1.2;

[0019] The recycled aggregate is then immersed or sprayed in the mixed liquid to obtain reinforced recycled aggregate.

[0020] Preferably, the soaking time in step S3 is 15 to 30 days, or the spraying pressure is above 0.20 MPa and the spraying time is 5 to 7 days.

[0021] Preferably, in step S4, the cleaned recycled aggregate is immersed in a culture solution containing the above-mentioned microorganisms, so that the microorganisms are attached to the surface of the aggregate and form a biofilm, and the culture is continued for a certain period of time to ensure that the microorganisms are effectively fixed and produce the required metabolites.

[0022] Preferably, in step S5, the recycled aggregate treated with microorganisms is taken out, gently rinsed, and appropriately dried;

[0023] As required, the dry aggregate, cement, fiber filler and other composite materials can be mixed for subsequent molding and curing.

[0024] Preferably, the microbial reinforced recycled aggregate includes the contents of claims 1-8.

[0025] Due to the adoption of the above technical solution, the present invention has the following technical advances compared with the prior art:

[0026] 1. The present invention provides a microbial enhanced recycled aggregate and a preparation method thereof. The curing operation needs to be carried out step by step during spraying or soaking, thereby solving the problem of insufficient carbon source supply during spraying or soaking, difficulty in effectively fixing and producing the required metabolites, and causing waste of resources, time and space.

[0027] 2. The present invention provides a microbial reinforced recycled aggregate and a preparation method thereof. By soaking the washed recycled aggregate in a microbial culture solution, its water absorption rate can be significantly reduced and the quality of the aggregate can be improved.

[0028] 3. The present invention provides a microbial enhanced recycled aggregate and a preparation method thereof. The soaking time in step S3 is 15 to 30 days, or the spraying pressure is above 0.20 MPa and the spraying time is 5 to 7 days, which can effectively reduce the porosity of the recycled aggregate and reduce the water absorption rate and crushing index value of the recycled aggregate. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 The present invention is a schematic flow chart of a method for preparing a microbial enhanced recycled aggregate. DETAILED DESCRIPTION

[0030] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0031] like Figure 1 As shown, a microbial enhanced recycled aggregate and a preparation method thereof, comprising the following steps:

[0032] S1. Prepare recycled aggregate;

[0033] S2, select microorganisms;

[0034] S3, culture microorganisms;

[0035] S4, immersion treatment;

[0036] S5. Drying and curing.

[0037] like Figure 1 As shown, in step S1, concrete, bricks, gravel, etc. are recovered from construction waste, and after crushing and screening, recycled aggregates with appropriate particle sizes are obtained (the particle size of the recycled aggregates is 0.15-4.75 mm or 10-20 mm).

[0038] like Figure 1 As shown, in step S2, bacteria that can promote cement hydration reaction (such as Bacillus pseudofirmus and Bacillus pasteurianus, the Bacillus pseudofirmus strain is numbered DSM8715, obtained from the China General Microbiological Culture Collection Management Center) are selected, and urea-decomposing bacteria are inoculated into a microbial culture medium for cultivation to obtain a microbial culture solution, which is capable of enhancing the strength of aggregate.

[0039] like Figure 1 As shown, the culture in step S3 is carried out under shaking conditions, the shaking frequency is 100-140 rpm; the culture temperature is 25-37° C., and the culture time is 10-48 h.

[0040] like Figure 1 As shown, the microbial culture solution obtained in step S3 is mixed with the mineralized culture solution to obtain a mixed culture solution;

[0041] The mass ratio of the recycled aggregate to the mixed culture solution is 1:1 to 1:1.2;

[0042] The recycled aggregate is then immersed or sprayed in the mixed liquid to obtain reinforced recycled aggregate.

[0043] like Figure 1 As shown, the soaking time in step S3 is 15 to 30 days, or the spraying pressure is above 0.20 MPa and the spraying time is 5 to 7 days.

[0044] like Figure 1 As shown, in step S4, the cleaned recycled aggregate is immersed in a culture solution containing the above-mentioned microorganisms, so that the microorganisms are attached to the surface of the aggregate and form a biofilm, and the culture is continued for a certain period of time to ensure that the microorganisms are effectively fixed and produce the required metabolites.

[0045] like Figure 1 As shown, in step S5, the recycled aggregate treated with microorganisms is taken out, gently rinsed, and appropriately dried;

[0046] As required, the dry aggregate, cement, fiber filler and other composite materials can be mixed for subsequent molding and curing.

[0047] like Figure 1 As shown, the microbial reinforced recycled aggregate includes the contents of claims 1-8.

[0048] The working principle of the invention is as follows: concrete, bricks, crushed stones and the like are recovered from construction waste, and recycled aggregates with appropriate particle sizes are obtained through crushing and screening; bacteria that can promote cement hydration reaction are selected, urea-decomposing bacteria are inoculated into a microbial culture medium for cultivation, a microbial culture solution is obtained, and fungi that can enhance the strength of aggregates are obtained, the microbial culture is carried out under oscillation conditions, and the oscillation frequency is 100-140 rpm; the culture temperature is 25-37° C., the culture time is 10-48 hours, the obtained microbial culture solution is mixed with a mineralized culture solution to obtain a mixed culture solution; the mass ratio of the recycled aggregate to the mixed culture solution is 1:1-1:1.2, and the recycled aggregate is then immersed or sprayed in the mixed solution, the immersion time is 15-30 days, or the spraying pressure is above 0.20 MPa, and the spraying time is 5-7 days, so as to obtain reinforced recycled aggregates; the recycled aggregates treated with microorganisms are taken out, gently rinsed, and appropriately dried, and as needed, the dried aggregates, cement, fiber fillers and other composite materials can be mixed for subsequent molding and curing treatment.

[0049] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A method for preparing microbial enhanced recycled aggregate, characterized in that: The preparation method comprises the following steps: S1. Prepare recycled aggregate; S2, select microorganisms; S3, culturing microorganisms; S4, impregnation treatment; S5. Drying and curing.

2. The method for preparing a microbial-enhanced recycled aggregate according to claim 1, characterized in that: In step S1, concrete, bricks, gravel, etc. are recovered from construction waste, and recycled aggregates with appropriate particle sizes are obtained through crushing and screening. The particle size of the recycled aggregates is 0.15-4.75 mm or 10-20 mm.

3. The method for preparing a microbial-enhanced recycled aggregate according to claim 1, characterized in that: In step S2, bacteria that can promote cement hydration reaction are selected, urea-decomposing bacteria are inoculated into a microbial culture medium and cultured to obtain a microbial culture solution, which is a fungus that can enhance the strength of aggregate.

4. The method for preparing a microbial-enhanced recycled aggregate according to claim 1, characterized in that: The culture in step S3 is carried out under shaking conditions, the shaking frequency is 100-140 rpm; the culture temperature is 25-37° C., and the culture time is 10-48 h.

5. The method for preparing a microbial-enhanced recycled aggregate according to claim 4, characterized in that: Mixing the microbial culture solution obtained in step S3 with the mineralized culture solution to obtain a mixed culture solution; The mass ratio of the recycled aggregate to the mixed culture solution is 1:1 to 1:1.2; The recycled aggregate is then immersed or sprayed in the mixed liquid to obtain reinforced recycled aggregate.

6. The method for preparing a microbial-enhanced recycled aggregate according to claim 5, characterized in that: The soaking time in step S3 is 15 to 30 days, or the spraying pressure is above 0.20 MPa and the spraying time is 5 to 7 days.

7. The method for preparing a microbial-enhanced recycled aggregate according to claim 1, characterized in that: In step S4, the cleaned recycled aggregate is immersed in a culture solution containing the above-mentioned microorganisms, so that the microorganisms are attached to the surface of the aggregate and form a biofilm, and the culture is continued for a certain period of time to ensure that the microorganisms are effectively fixed and produce the required metabolites.

8. The method for preparing recycled aggregate enhanced by microorganisms according to claim 1, characterized in that: In step S5, the recycled aggregate treated with microorganisms is taken out, gently rinsed, and appropriately dried; As required, dry aggregate, cement, fiber filler binder materials can be mixed for subsequent molding and curing.

9. The microbial enhanced recycled aggregate according to claim 1, characterized in that: The microbial reinforced recycled aggregate includes the contents of claims 1-8.

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