A biological reinforcement and corrosion protection process for bridge pier cracks

Abstract

This invention discloses a biological reinforcement and corrosion protection process for bridge pier cracks, comprising: S1, extracting calcium ions from South China Sea calcareous sand to obtain a calcium chloride solution; S2, installing a reaction sleeve mold reaction device at the location of the cracked bridge pier, filling the gap between the bridge pier and the mold reaction device with South China Sea calcareous sand particles in three batches, and injecting bacterial solution, urea, and the calcium chloride solution obtained in step S1 in batches for cyclic infusion, and repeating the cyclic infusion process. This invention, by using the calcium chloride solution extracted from South China Sea calcareous sand and the bacterial solution for cyclic infusion, can achieve biological reinforcement of bridge pier cracks, resulting in better compatibility and permeability with the bridge pier substrate material. It can penetrate even the smallest cracks, and the generated calcium carbonate crystals can effectively and better bond with the bridge pier substrate material, playing a role in filling and bonding cracks. It also has the advantages of low cost, convenient material sourcing, few and safe byproducts, and no pollution to the marine environment.

Description

Technical Field

[0001] This invention relates to a biological reinforcement and corrosion protection process for bridge pier cracks. Background Technology

[0002] The construction of islands is booming worldwide, with numerous cross-sea bridges emerging, especially in recent years with my country's massive investment in the construction of islands in the South China Sea. Concrete possesses excellent compressive strength and durability, along with good workability, making it the most common material in buildings and bridges. Common defects in concrete bridge structures include cracks, spalling, honeycombing, and voids. However, the final form of these defects is cracking. Although cracks are evaluated as part of durability under normal service conditions in codes, structural damage and even collapse often begin with the expansion of cracks, gradually transforming a safe state into an unsafe state over time.

[0003] Traditional methods for repairing bridge pier cracks include: interface enlargement reinforcement, external prestressing reinforcement, and embedded reinforcement. Interface enlargement reinforcement involves wrapping the surface of the existing column with a layer of concrete, thereby increasing the cross-sectional area and reinforcement of the component. This conventional reinforcement technique can improve the load-bearing capacity of the reinforced component, increase its cross-sectional stiffness, change its natural frequency, and improve its performance during normal service. External prestressing reinforcement, due to the prestressing effect, can offset some of the load effect in the cracks, changing the stress state of the pier. It can both remedy existing cracks and prevent the development of new cracks. Embedded reinforcement involves embedding reinforcing bars (high-strength steel bars, FRP bars, etc.) into pre-cut grooves in the structural surface (concrete cover), and injecting resin bonding material into the grooves to form a whole, thereby improving structural performance.

[0004] However, the above traditional methods either require altering the original pier structure or creating larger openings in the piers before reinforcement, and cannot fundamentally eliminate cracks in piers that have already developed cracks. Moreover, cross-sea bridges are located in the ocean, in a complex environment, far from the inland, where high-quality materials required for construction such as concrete and high-strength steel reinforcement are scarce. In particular, various raw materials for cement columns, especially calcium chloride, can only be transported from outside, and transporting them from the inland would be extremely costly. Summary of the Invention

[0005] In order to overcome the shortcomings of the prior art, the primary objective of this invention is to provide a biological reinforcement and corrosion protection process for bridge pier cracks.

[0006] This invention is achieved through the following technical solution:

[0007] A biological reinforcement and corrosion protection process for bridge pier cracks includes the following steps:

[0008] S1. Calcium chloride solution was obtained by extracting calcium ions from calcareous sand in the South China Sea.

[0009] S2. At the bridge pier where the crack was found, a reaction sleeve mold reaction device was installed. The South China Sea calcareous sand particles were loaded into the gap between the bridge pier and the mold reaction device in three batches. Bacterial liquid, urea and calcium chloride solution obtained in step S1 were injected in batches for cyclic injection, and the cyclic injection process was repeated.

[0010] Step S1 includes the following specific steps:

[0011] S1-1. Weigh the South China Sea calcareous sand and feed it into the crusher for mechanical crushing into small-diameter particles to obtain crushed South China Sea calcareous sand.

[0012] S1-2, dilute hydrochloric acid and crushed South China Sea calcareous sand are introduced into a calcium ion extraction reactor for the first reaction to produce calcium chloride solution, carbon dioxide gas and water;

[0013] S1-3. The reaction mixture flowing out of the bottom of the calcium ion extraction reactor will be further separated in the sedimentation tank. The unreacted South China Sea calcium sand will be returned to the calcium ion extraction reactor for a second reaction to generate calcium chloride solution. The calcium chloride solution and the calcium chloride solution generated in the first reaction in step S1-2 will be collected as the final extraction product calcium chloride solution.

[0014] S1-4. Simultaneously, the remaining mixture is fed into a microfiltration system for further separation and purification. The product solution after passing through the microfiltration system will undergo a neutralization reaction in an acid-base neutralization reactor to obtain a sodium chloride solution with a certain salinity.

[0015] In step S2, the reaction sleeve mold reaction device is made of two semi-cylindrical PVC material tubes spliced ​​together, and has A port, B port, C port and D port respectively. The splice is waterproof and can be disassembled and reused.

[0016] Step S2 includes the following specific steps: South China Sea calcareous sand particles are filled into the gap between the bridge pier and the reaction sleeve mold reaction device in three stages. After the first layer of South China Sea calcareous sand particles is filled, bacterial solution is injected from port A, flows out through port B, and circulates back to port A for 8-10 hours without adding urea or calcium chloride solution. After 8-10 hours, the circulation of bacterial solution is stopped, and urea and calcium chloride solution are added for 13-17 hours of cyclic infusion. After 22-26 hours, another layer of South China Sea calcareous sand particles is filled, and the previous cyclic infusion process is repeated from port A to port C. After 46-50 hours, a final layer of South China Sea calcareous sand particles is filled, and the cyclic infusion process is repeated from port A to port D.

[0017] In step S1-1), the particle size of the crushed South China Sea calcareous sand is <0.5mm.

[0018] In step S1-2), the concentration of the dilute hydrochloric acid is 35-40%; the mass ratio of the dilute hydrochloric acid to the crushed South China Sea calcareous sand is 2.0-2.5:1.

[0019] In steps S1-3), the reaction mixture flowing out from the bottom of the calcium ion extraction reaction vessel consists of calcium chloride, water, unreacted South China Sea calcareous sand, residual dilute hydrochloric acid, and colloidal natural polysaccharide product EPS; the product solution after passing through the microfiltration system consists of water, calcium chloride, and a small amount of dilute hydrochloric acid; the microfiltration system is a membrane filter system; the alkali in the acid-base neutralization reactor is sodium hydroxide; and the salinity of the sodium chloride solution containing a certain salinity is 5-10 g / L NaCl.

[0020] The particle size of the South China Sea calcareous sand particles is 1-3 mm; the calcium chloride solution is prepared from the final extracted product calcium chloride solution obtained in steps S1-3) to a calcium chloride concentration of 6-8 g / L; and the concentration of urea is 18-22 g / L.

[0021] The types of bacteria used in the bacterial solution for reinforcement and the basic conditions for culturing the bacteria are as follows:

[0022] • Biological species: Bacillus basalis;

[0023] • Culture medium composition: casein peptone (15 g / L), calcium chloride (5 g / L), soybean peptone (5 g / L), pH 7.3;

[0024] • Culture conditions: Culture (30℃), 12-18 hours, 150 rpm;

[0025] • Test particle size: 0.5mm, 1mm and 2mm.

[0026] The present invention also discloses the application of the above-mentioned biological reinforcement and corrosion prevention technology for bridge pier cracks in the biological reinforcement and corrosion prevention of bridge pier cracks.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) This invention uses calcium ions extracted from calcareous sand in the South China Sea to obtain calcium chloride solution. By circulating the extracted calcium chloride solution with bacterial liquid, calcium carbonate in the calcareous sand in the South China Sea can be directly converted into calcium chloride, and biological reinforcement of bridge pier cracks can be achieved. This results in better coordination and permeability with the bridge pier substrate material, and can penetrate into the smallest cracks. The generated calcium carbonate crystals (biocement) can effectively combine with the bridge pier substrate material, playing the role of filling and bonding cracks. It also has the advantages of low cost, convenient material sourcing, few by-products and safety, and no pollution to the marine environment.

[0029] (2) The present invention provides biological reinforcement of bridge pier cracks, and at the same time, a protective layer formed by biologically reinforced South China Sea calcareous sand particles will be generated on the outer surface of the bridge pier, which can effectively prevent the impact and corrosion of the surrounding environment on the bridge body. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the process for biological reinforcement and corrosion protection of bridge pier cracks according to the present invention.

[0031] Figure 2 This is a schematic diagram of the structure of the bridge pier reinforcement device of the present invention;

[0032] Figure 3 This is a cross-sectional schematic diagram of the bridge pier reinforcement device of the present invention;

[0033] Figure 4 This is a schematic diagram of the extraction device for extracting calcium ions using calcareous sand from the South China Sea, as described in this invention. Detailed Implementation

[0034] The present invention will be further illustrated below through specific embodiments. The following embodiments are specific implementations of the present invention, but the implementation of the present invention is not limited to the following embodiments.

[0035] The raw materials used in the embodiments and comparative examples of this invention were all purchased from the market.

[0036] Microfiltration system: Hangzhou Kailu Membrane Technology Co., Ltd., Model: MBR equipment (complete set).

[0037] Test method for quality before (after) reinforcement: measurement by weighing.

[0038] Test method for porosity before (after) reinforcement: Considering the concept of relative porosity, the mass obtained by weighing before reinforcement is calculated (the sample volume is equal before and after the test, and the conversion is made by measuring the mass).

[0039] Test method for unconfined compressive strength: The standard specimen size for the compressive strength test should have a diameter-to-height ratio of 1:2. The instrument used for the compressive strength test is an electronic universal testing machine manufactured by MES Industrial Systems (China), model E45.105. The test setting is a loading speed of 0.5 mm / min. The specimen is placed stably on the platform, and loading is continued until the specimen shows obvious failure. During the process, the instrument collects data through pressure and displacement sensors and transmits it to the computer operating platform. The software platform generates stress-strain curves in real time, and finally obtains the unconfined compressive strength result of the specimen.

[0040] Example 1:

[0041] like Figure 1 As shown, a biological reinforcement and corrosion protection process for bridge pier cracks includes the following steps:

[0042] S1. Calcium chloride solution is obtained by extracting calcium ions from calcareous sand in the South China Sea. The process flow is as follows: Figure 4 As shown;

[0043] Step S1 includes the following specific steps:

[0044] S1-1. Weigh the South China Sea calcareous sand and feed it into a crusher for mechanical crushing into small-diameter particles to obtain crushed South China Sea calcareous sand; particles crushed to <0.5mm diameter are used to extract calcium chloride solution; particles crushed to 1-3mm diameter are used to generate a protective layer on the outer surface of bridge piers.

[0045] S1-2, 35% dilute hydrochloric acid and crushed South China Sea calcareous sand with a particle size <0.5mm are fed into the calcium ion extraction reactor at a mass ratio of 2.5:1 to carry out the first reaction to produce calcium chloride solution, carbon dioxide gas and water;

[0046] S1-3. The reaction mixture flowing out of the bottom of the calcium ion extraction reactor will be further separated in the sedimentation tank. The unreacted South China Sea calcium sand will be returned to the calcium ion extraction reactor for a second reaction to generate calcium chloride solution. The calcium chloride solution and the calcium chloride solution generated in the first reaction in step S1-2 will be collected as the final extraction product calcium chloride solution.

[0047] S1-4. Due to the addition of dilute hydrochloric acid in the aforementioned steps, the calcium chloride solution is acidic and contains some remaining impurities. Further filtration and neutralization of the mixed solution are necessary: ​​first, the remaining mixture is fed into a microfiltration system for further separation and purification. The product solution after microfiltration will be as follows: Figure 4 The neutralization reaction is carried out in the acid-base neutralization reactor shown to obtain a sodium chloride solution with a certain salinity;

[0048] The reaction mixture flowing out from the bottom of the calcium ion extraction reaction vessel consists of calcium chloride, water, unreacted South China Sea calcareous sand, residual dilute hydrochloric acid, and colloidal natural polysaccharide product EPS; the product solution after passing through the microfiltration system consists of water, calcium chloride, and a small amount of dilute hydrochloric acid; the microfiltration system is a membrane filter system; the alkali in the acid-base neutralization reactor is sodium hydroxide; and the salinity of the sodium chloride solution containing a certain salinity is 5 g / L.

[0049] S2. At the pier where cracks are found, install as follows: Figure 2 and Figure 3 The reaction sleeve mold reaction device shown is composed of two semi-cylindrical PVC material pipes spliced ​​together, with ports A, B, C, and D respectively. The splice is waterproof and can be disassembled and reused. South China Sea calcareous sand particles are filled into the gap between the bridge pier and the reaction sleeve mold reaction device in three stages. After the first layer of South China Sea calcareous sand particles is filled, bacterial solution is injected through port A, flows out through port B, and circulates back to port A. This circulation lasts for 10 hours, during which no urea (concentrated) is added. The bacterial solution (calcium chloride solution with a concentration of 18 g / L) and the final extract product calcium chloride solution obtained from steps S1-3 were mixed to a calcium chloride solution with a concentration of 6-8 g / L; after 10 hours, the circulation of the bacterial solution was stopped, and urea and calcium chloride solution were added and circulated for 13 hours; after 26 hours, another layer of South China Sea calcareous sand particles was filled, and the previous circulation and irrigation process was repeated from port A to port C; after 46 hours, a final layer of South China Sea calcareous sand particles was filled, and the circulation and irrigation process was repeated from port A to port D;

[0050] The types of bacteria used in the bacterial solution for reinforcement and the basic conditions for culturing the bacteria are as follows:

[0051] • Biological species: Bacillus spasii;

[0052] • Culture medium composition: casein peptone (15 g / L), calcium chloride (5 g / L), soybean peptone (5 g / L), pH 7.3;

[0053] • Culture conditions: Culture (30℃), 12-18 hours, 150 rpm;

[0054] • Test particle size: 0.5mm, 1mm and 2mm.

[0055] Example 2:

[0056] A biological reinforcement and corrosion protection process for bridge pier cracks includes the following steps:

[0057] S1. Calcium chloride solution was obtained by extracting calcium ions from calcareous sand in the South China Sea.

[0058] Step S1 includes the following specific steps:

[0059] S1-1. Weigh the South China Sea calcareous sand and feed it into a stone crusher for mechanical crushing into small-diameter particles to obtain crushed South China Sea calcareous sand; particles crushed to <0.5mm diameter are used to extract calcium chloride solution; particles crushed to 3mm diameter are used to generate a protective layer on the outer surface of bridge piers.

[0060] S1-2, 40% dilute hydrochloric acid and crushed South China Sea calcareous sand with a particle size <0.5mm are fed into the calcium ion extraction reactor at a mass ratio of 2.0:1 to carry out the first reaction to produce calcium chloride solution, carbon dioxide gas and water;

[0061] S1-3. The reaction mixture flowing out of the bottom of the calcium ion extraction reactor will be further separated in the sedimentation tank. The unreacted South China Sea calcium sand will be returned to the calcium ion extraction reactor for a second reaction to generate calcium chloride solution. The calcium chloride solution and the calcium chloride solution generated in the first reaction in step S1-2 will be collected as the final extraction product calcium chloride solution.

[0062] S1-4. Since dilute hydrochloric acid was added in the above steps, the calcium chloride solution is acidic and contains some remaining impurities. The mixed solution needs to be further filtered and neutralized: the remaining mixture is first put into a microfiltration system for further separation and purification. The product solution after passing through the microfiltration system will be neutralized in an acid-base neutralization reactor to obtain a sodium chloride solution with a certain salinity.

[0063] The reaction mixture flowing out from the bottom of the calcium ion extraction reaction vessel consists of calcium chloride, water, unreacted South China Sea calcareous sand, residual dilute hydrochloric acid, and colloidal natural polysaccharide product EPS; the product solution after passing through the microfiltration system consists of water, calcium chloride, and a small amount of dilute hydrochloric acid; the microfiltration system is a membrane filter system; the alkali in the acid-base neutralization reactor is sodium hydroxide; and the salinity of the sodium chloride solution containing a certain salinity is 10 g / L.

[0064] S2. At the pier where cracks are found, install as follows: Figure 2 and Figure 3The reaction sleeve mold reaction device shown is composed of two semi-cylindrical PVC material pipes spliced ​​together, with ports A, B, C, and D respectively. The splice is waterproof and can be disassembled and reused. South China Sea calcareous sand particles are filled into the gap between the bridge pier and the reaction sleeve mold reaction device in three stages. After the first layer of South China Sea calcareous sand particles is filled, bacterial solution is injected through port A, flows out through port B, and circulates back to port A. This circulation lasts for 8 hours without the addition of urea. The concentration of the bacterial solution was 18 g / L, and the calcium chloride solution (the final extract obtained from steps S1-3) was mixed to a calcium chloride concentration of 8 g / L. After 8 hours, the circulation of the bacterial solution was stopped, and urea and calcium chloride solution were added and circulated for 17 hours. After 22 hours, another layer of South China Sea calcareous sand particles was filled, and the previous circulation and irrigation process was repeated from port A to port C. After 50 hours, a final layer of South China Sea calcareous sand particles was filled, and the circulation and irrigation process was repeated from port A to port D.

[0065] The types of bacteria used in the bacterial solution for reinforcement and the basic conditions for culturing the bacteria are as follows:

[0066] • Biological species: Bacillus spasii;

[0067] • Culture medium composition: casein peptone (15 g / L), calcium chloride (5 g / L), soybean peptone (5 g / L), pH 7.3;

[0068] • Culture conditions: Culture (30℃), 12-18 hours, 150 rpm;

[0069] • Test particle size: 0.5mm, 1mm and 2mm.

[0070] Comparative Example 1:

[0071] Calcium carbonate and acetic acid need to react at a relatively high temperature (50°C). The calcium ions generated are mainly calcium acetate. The reinforcement experiment on the bridge pier cracks was carried out, and the other steps were the same as in Example 1.

[0072] Comparative Example 2:

[0073] The traditional method of using solid calcium chloride to reinforce bridge pier cracks was adopted, and other steps were the same as in Example 1.

[0074] Application of the processes in Examples 1-2 and Comparative Examples 1-2 in the biological reinforcement of bridge pier cracks:

[0075] Before reinforcing the bridge piers, the strength of the reinforcing cement was tested. Using a model with a radius and height of 1:2, biologically reinforced cement columns were made using 0.5mm diameter South China Sea calcareous sand particles, as described above. Unconfined compressive strength (UCS) tests were conducted to measure the mass before and after reinforcement, the porosity before and after reinforcement, and the unconfined compressive strength. The test results are shown in Table 1.

[0076] Table 1

[0077] Example 1 Example 2 Comparative Example 1 Comparative Example 2 Mass before reinforcement / g 38.82 38.05 32.36 33.23 Mass after reinforcement / g 49.07 45.37 31.44 32.89 Relative porosity / % 20.89 18.27 7.43 8.87 Unconfined compressive strength / MPa 6.16 5.34 2.96 2.34

[0078] Application of the processes in Examples 1-2 and Comparative Examples 1-2 in corrosion prevention of bridge pier cracks:

[0079] The samples from Examples 1-2 and Comparative Examples 1-2 were placed in a weakly alkaline environment with pH=9 for one month to simulate corrosion. After one month, an unconfined compressive strength test was conducted again, and the unconfined compressive strength after one month was recorded to characterize the corrosion resistance performance. The test results are shown in Table 2.

[0080] Table 2

[0081]

[0082] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A biological reinforcement and corrosion protection process for bridge pier cracks, characterized in that, Includes the following steps: S1. Calcium chloride solution was obtained by extracting calcium ions from calcareous sand in the South China Sea. S2. At the bridge pier where the crack was found, a reaction sleeve mold reaction device was installed. The South China Sea calcareous sand particles were loaded into the gap between the bridge pier and the mold reaction device in three batches. Bacterial liquid, urea and calcium chloride solution obtained in step S1 were injected in batches for cyclic injection, and the cyclic injection process was repeated. In step S2, the reaction sleeve mold reaction device is made of two semi-cylindrical PVC material tubes spliced ​​together, and has A port, B port, C port and D port respectively. The splice is waterproof and can be disassembled and reused. Step S2 includes the following specific steps: South China Sea calcareous sand particles are filled into the gap between the bridge pier and the reaction sleeve mold reaction device in three stages. After the first layer of South China Sea calcareous sand particles is filled, bacterial solution is injected from port A, flows out through port B, and circulates back to port A for 8-10 hours without adding urea or calcium chloride solution. After 8-10 hours, the circulation of bacterial solution is stopped, and urea and calcium chloride solution are added for 13-17 hours of cyclic infusion. After 22-26 hours, another layer of South China Sea calcareous sand particles is filled, and the previous cyclic infusion process is repeated from port A to port C. After 46-50 hours, a final layer of South China Sea calcareous sand particles is filled, and the cyclic infusion process is repeated from port A to port D.

2. The biological reinforcement and corrosion protection process for bridge pier cracks according to claim 1, characterized in that, Step S1 includes the following specific steps: S1-1. Weigh the South China Sea calcareous sand and feed it into the crusher for mechanical crushing into small-diameter particles to obtain crushed South China Sea calcareous sand. S1-2, dilute hydrochloric acid and crushed South China Sea calcareous sand are introduced into a calcium ion extraction reactor for the first reaction to produce calcium chloride solution, carbon dioxide gas and water; S1-3. The reaction mixture flowing out of the bottom of the calcium ion extraction reactor will be further separated in the sedimentation tank. The unreacted South China Sea calcium sand will be returned to the calcium ion extraction reactor for a second reaction to generate calcium chloride solution. The calcium chloride solution and the calcium chloride solution generated in the first reaction in step S1-2 will be collected as the final extraction product calcium chloride solution. S1-4. Simultaneously, the remaining mixture is fed into a microfiltration system for further separation and purification. The product solution after passing through the microfiltration system will undergo a neutralization reaction in an acid-base neutralization reactor to obtain a sodium chloride solution with a certain salinity.

3. The biological reinforcement and corrosion protection process for bridge pier cracks according to claim 2, characterized in that, In step S1-1, the particle size of the crushed South China Sea calcareous sand is <0.5 mm.

4. The biological reinforcement and corrosion protection process for bridge pier cracks according to claim 2, characterized in that, In steps S1-2, the concentration of the dilute hydrochloric acid is 35-40%; the mass ratio of the dilute hydrochloric acid to the crushed South China Sea calcareous sand is 2.0-2.5:

1.

5. The biological reinforcement and corrosion protection process for bridge pier cracks according to claim 2, characterized in that, In steps S1-3, the reaction mixture flowing out from the bottom of the calcium ion extraction reaction vessel consists of calcium chloride, water, unreacted South China Sea calcareous sand, residual dilute hydrochloric acid, and colloidal natural polysaccharide product EPS; the product solution after passing through the microfiltration system consists of water, calcium chloride, and a small amount of dilute hydrochloric acid; the microfiltration system is a membrane filter system; the alkali in the acid-base neutralization reactor is sodium hydroxide; and the salinity of the sodium chloride solution containing a certain salinity is 5~10 g / L NaCl.

6. The biological reinforcement and corrosion protection process for bridge pier cracks according to claim 1, characterized in that, The particle size of the South China Sea calcareous sand particles is 1-3 mm; the calcium chloride solution is prepared from the final extracted product calcium chloride solution obtained in steps S1-3 to a calcium chloride concentration of 6-8 g / L; the concentration of the urea is 18-22 g / L.

7. The application of the bio-reinforcement and corrosion protection technology for bridge pier cracks as described in claim 1 in the bio-reinforcement and corrosion protection of bridge pier cracks.

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