Concrete crack repairing method

Abstract

The invention provides a concrete crack repairing method. The concrete crack repairing method is characterized in that a concrete block, an electrolytic tank, a positive electrode and a negative electrode are included; cracks are formed in the surfaces of the concrete blocks; the electrolytic tank comprises a cathode tank and an anode tank which are isolated from each other; the repairing method comprises the following steps: 1) injecting a silicate solution into the cathode tank, injecting a calcium salt solution into the anode tank, putting the negative electrode into the silicate solution, and putting the positive electrode into the calcium salt solution; completely immersing the cracks of the concrete blocks into the silicate solution; (2) an electric field is applied between the positive electrode and the negative electrode, the environment temperature is kept at 10-30 DEG C for 7-28 days, the silicate solution is replaced once every day during the period, and the electric field intensity of the electric field is 6-24 V / cm. By means of the repairing method, the original mechanical performance of concrete can be guaranteed, meanwhile, the bonding performance and the fusion degree of cracks are improved, and the service life of the cracks is prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of civil engineering material repair, and particularly to a method for repairing concrete cracks. Background Art

[0002] Due to advantages such as wide raw material sources, good performance, and low price, concrete is widely used in civil engineering around the world today. However, during the preparation process of concrete, there are a large number of micro-cracks and pores inside, and cracks are very likely to occur during service. This not only greatly shortens its service life but also causes huge economic losses and may even lead to serious safety accidents. Therefore, it is an urgent problem to be solved currently to efficiently and economically repair concrete cracks. Traditional crack repair technologies, such as reinforcement repair method, grouting method, filling method, concrete replacement method, etc., still have great limitations in the repair of concrete structure cracks in a water environment. Not only is the construction difficulty relatively large, but in many cases, the repair effect is difficult to guarantee.

[0003] As a new method for repairing concrete structure cracks, the electrodeposition technology has advantages such as high efficiency, economy, and no pollution. In the prior art, usually, a suitable mineral electrolyte is used as an external electrolyte solution (Zn 2+ 、Mg 2+ salt electrolyte solution), an inert metal placed in the external electrolyte solution is used as the anode, and the steel bars in the concrete structure with cracks are used as the cathode. A certain direct current is applied between the cathode and the anode. Positive and negative ions move towards the steel bars in the concrete and the external environment respectively. The cations migrating from the external electrolyte solution to the concrete will react with the products contained in the concrete itself or generated by the electrode reaction to form insoluble substances, so that a layer of sediment is generated in and on the surface of the concrete structure cracks, thereby achieving the purpose of crack repair.

[0004] However, the above method has the following problems: Firstly, using steel bars as the cathode will cause hydrogen embrittlement during the reaction process, resulting in a decrease in the bonding force between the steel bars and the concrete, and damaging and reducing the mechanical properties of the concrete itself; Secondly, the sediments generated by the above method (such as ZnO and Mg(OH) 2 etc.) have large differences in composition and properties from the main component cement of the concrete. These sediments have poor adhesion when filled into the cracks and are very likely to crack again or even fall off. Summary of the Invention

[0005] Aiming at the problems in the background art, the present invention provides a method for repairing concrete cracks to solve the problems that the crack fillers generated after repairing concrete cracks in the prior art have poor adhesion, are easy to crack and fall off, and affect the strength of the concrete itself.

[0006] To achieve the object of the present invention, the present invention provides a method for repairing concrete cracks, and its innovation lies in: including a concrete block, an electrolytic cell, a positive electrode and a negative electrode; there are cracks on the surface of the concrete block; the electrolytic cell includes a cathode cell and an anode cell that are isolated from each other; the repair method includes: 1) Inject a silicate solution into the cathode cell, inject a calcium salt solution into the anode cell, place the negative electrode in the silicate solution, and place the positive electrode in the calcium salt solution; then completely immerse the cracks of the concrete block in the silicate solution; 2) Apply an electric field between the positive electrode and the negative electrode, and maintain it for 7 to 28 days at an ambient temperature of 10°C to 30°C, and replace the silicate solution once a day during this period; The electric field strength of the electric field is 6V / cm to 24V / cm.

[0007] Further, the silicate solution is a sodium silicate solution or a potassium silicate solution; the calcium salt solution is a calcium hydroxide solution or a calcium nitrate solution.

[0008] Further, the concentration of the silicate solution is 0.01mol / L to 1mol / L; the concentration of the calcium salt solution is 0.05mol / L to 1mol / L.

[0009] Further, the positive electrode and the negative electrode are made of a platinum mesh, a stainless steel mesh or a titanium mesh.

[0010] Thus, the present invention has the following beneficial effects: Since the steel bars inside the concrete are no longer used as the cathode, but the repair is carried out by setting up a cathode cell outside the concrete, the hydrogen embrittlement phenomenon of the steel bars that may occur in the electro-deposition method is avoided, thereby ensuring that the original mechanical properties of the concrete will not be damaged during the repair process. On the other hand, the present invention uses a silicate solution as the reaction solution in the cathode cell, and the deposited filler generated by the reaction is a substance mainly composed of hydrated calcium silicate and calcium carbonate, which is similar to the main components of the cement in the concrete, and can greatly improve the bonding effect and fusion degree of the deposited filler in the cracks with the concrete, and improve the service life of the crack filling. At the same time, since during the reaction process, the silicate reacts with the concrete and consumes substances such as Ca(OH) in the concrete itself, resulting in a decrease in the Ca ion concentration in the concrete, the present invention adds a calcium salt solution to the anode cell, and continuously supplements Ca ions through the driving of the electric field. This mechanism not only ensures the sufficient generation of hydrated calcium silicate, but also maintains the Ca 2 dynamic balance, avoiding the weakening of the microscopic structure of the concrete caused by the consumption of calcium ions, and thus stabilizing its alkaline environment. 2+ BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The drawings of the present invention are described as follows.

[0012] Appendix​Figure 1 Schematic structural diagram of the device adopted in the present invention.

[0013] In the figure: 1, concrete block; 2, electrolytic cell; 3, positive electrode; 4, negative electrode; 21, cathode cell; 22, anode cell. Specific implementation mode

[0014] The present invention will be further described below in conjunction with embodiments.

[0015] The method for repairing concrete cracks according to the present invention involves a device including a concrete block 1, an electrolytic cell 2, a positive electrode 3 and a negative electrode 4; there are cracks on the surface of the concrete block 1; the electrolytic cell 2 includes a cathode cell 21 and an anode cell 22 that are isolated from each other; the repair method includes: 1) Inject a silicate solution into the cathode cell 21, inject a calcium salt solution into the anode cell 22, place the negative electrode 4 in the silicate solution, and place the positive electrode 3 in the calcium salt solution; then immerse the cracks of the concrete block 1 completely in the silicate solution. 2) Apply an electric field between the positive electrode 3 and the negative electrode 4, and maintain it for 7 to 28 days at an ambient temperature of 10°C to 30°C. During this period, replace the silicate solution once a day. The electric field strength of the electric field is 6V / cm to 24V / cm.

[0016] In order to improve the quality of the crack deposition filler, the silicate solution is a sodium silicate solution or a potassium silicate solution; the calcium salt solution is a calcium hydroxide solution or a calcium nitrate solution.

[0017] In order to achieve the best reaction effect, the concentration of the silicate solution is 0.01mol / L to 1mol / L; the concentration of the calcium salt solution is 0.05mol / L to 1mol / L.

[0018] In order to ensure the best reaction effect, the positive electrode and the negative electrode are made of platinum mesh, stainless steel mesh or titanium mesh. To verify the effect of the present invention, the inventor conducted the following experiments: A fine aggregate concrete structure specimen with a molding size of 40mm×40mm×160mm was prepared. The cement was 42.5-grade ordinary Portland cement, the water-cement ratio was 0.45, and the ash-sand ratio was 1:2.5. During the molding of the concrete structure specimen, steel feeler gauges were used to prefabricate concrete cracks. The crack width and crack depth were controlled by the size of the steel feeler gauges. After molding, it was placed in a standard curing room. After the concrete structure specimen was cured under standard conditions for 28 days, it was placed in an electrolytic cell, with the crack opening in the cathode cell. A certain concentration of calcium hydroxide solution and sodium silicate solution were respectively poured into the anode cell and the cathode cell. Titanium meshes were placed in the solutions of the anode cell and the cathode cell as metal electrodes, and a DC power supply was connected.

[0019] Example 1: The crack width of the concrete specimen is 0.5 mm, the crack depth is 10 mm, the calcium hydroxide solution used is a saturated solution, the concentration of the sodium silicate solution is 0.05 mol / L, the applied voltage is 48 V, the solution temperature is fixed at 25 °C, the power-on time is 7 days, and the solution is replaced once a day during power-on to maintain the concentration. The concrete crack healing rate and crack filling depth are measured to be 100% and 10 mm, the surface coverage rate of the sediment is 9.2%, and the concrete mass increase rate is 1.06% compared with the untreated specimen.

[0020] Example 2: The crack width of the concrete specimen is 1 mm, the crack depth is 15 mm, the calcium hydroxide solution used is a saturated solution, the concentration of the sodium silicate solution is 0.05 mol / L, the applied voltage is 48 V, the solution temperature is fixed at 25 °C, the power-on time is 7 days. The concrete crack healing rate and crack filling depth are measured to be 100% and 15 mm, the surface coverage rate of the sediment is 11.7%, and the concrete mass increase rate is 1.23% compared with the untreated specimen.

[0021] Example 3: The crack width of the concrete specimen is 1 mm, the crack depth is 15 mm, the calcium hydroxide solution used is a saturated solution, the concentration of the sodium silicate solution is 0.05 mol / L, the applied voltage is 96 V, the solution temperature is fixed at 25 °C, the power-on time is 7 days. The concrete crack healing rate and crack filling depth are measured to be 83.5% and 13.2 mm, the surface coverage rate of the sediment is 6.3%, and the concrete mass increase rate is 1.1% compared with the untreated specimen.

[0022] Example 4: The crack width of the concrete specimen is 1 mm, the crack depth is 15 mm, the calcium hydroxide solution used is a saturated solution, the concentration of the sodium silicate solution is 0.05 mol / L, the applied voltage is 48 V, the solution temperature is fixed at 25 °C, the power-on time is 28 days. The concrete crack healing rate and crack filling depth are measured to be 100% and 15 mm, the surface coverage rate of the sediment is 26.7%, and the concrete mass increase rate is 1.75% compared with the untreated specimen.

Claims

1. A method for repairing concrete cracks, characterized in that: The invention comprises a concrete block, an electrolytic cell, a positive electrode and a negative electrode; the surface of the concrete block has cracks; the electrolytic cell comprises a cathode pool and an anode pool which are isolated from each other; and the repair method comprises: 1) Inject silicate solution into the cathode tank, inject calcium salt solution into the anode tank, place the negative electrode in the silicate solution, and place the positive electrode in the calcium salt solution; then completely immerse the cracks in the concrete block in the silicate solution; 2) applying an electric field between the positive electrode and the negative electrode, maintaining the field at an ambient temperature of 10°C to 30°C for 7 to 28 days, during which the silicate solution is replaced once a day; The electric field strength of the electric field is 6V / cm~24V / cm.

2. The method for repairing concrete cracks according to claim 1, characterized in that: The silicate solution is a sodium silicate solution or a potassium silicate solution; the calcium salt solution is a calcium hydroxide solution or a calcium nitrate solution.

3. The method for repairing concrete cracks according to claim 1 or 2, characterized in that: The concentration of the silicate solution is 0.01 mol / L to 1 mol / L; the concentration of the calcium salt solution is 0.05 mol / L to 1 mol / L.

4. The method for repairing concrete cracks according to claim 1 or 2, characterized in that: The positive electrode and the negative electrode are both made of platinum mesh, stainless steel mesh or titanium mesh.

5. The method for repairing concrete cracks according to claim 3, characterized in that: The positive electrode and the negative electrode are both made of platinum mesh, stainless steel mesh or titanium mesh.

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