Concrete crack self-repairing agent suitable for marine corrosion conditions

Abstract

The application discloses a kind of concrete crack self-repairing agent suitable for marine corrosion conditions, including component one and component two;The component one, component two are all core-shell structure;The outer shell of component one is polymer film;Inner layer includes the following components by mass percentage: 20%-30% barite powder, 50%-60% magnesium source, 20%-30% cement;The outer shell of component two is polymer film;Inner layer includes the following components by mass percentage: 20-30% barite powder, 5-10% microbial powder, 20-30% glucose, 20%-40% aluminum source, 10%-30% low-alkali cement.The repairing agent of the application is continuous grading solid particle pellet, and the fine aggregate of concrete is replaced with equal mass.By the synergistic effect of microbial mineralization and metal mineral hydration, the filling of concrete crack space and the solidification of invasive crack corrosion ions are realized, especially suitable for marine corrosion environment.

Description

TECHNICAL FIELD

[0001] The present application relates to a concrete repair agent, in particular to a concrete crack self-repairing agent suitable for marine corrosion conditions. BACKGROUND

[0002] Concrete is a typical brittle material, which is prone to cracking during service. It has been a common understanding in the current engineering field that concrete with cracks is in service. However, when concrete is in service in a strong corrosion environment such as seawater, corrosion ions rich in seawater will enter the interior of the concrete along the cracks, causing steel corrosion, producing expansive products, and greatly accelerating the deterioration rate of concrete. Therefore, concrete in marine environment should take measures in time at the early stage of cracking to limit the further development of cracks, so as to avoid rapid development of cracks and lead to structural failure and serious safety accidents.

[0003] For underwater parts or complex structure parts, it is difficult to implement manual supervision. When cracks occur in concrete, it is difficult to find and take manual repair measures, which will lead to continuous expansion of cracks. Self-repairing concrete can realize autonomous exploration and active repair of concrete cracks, which can better avoid the disrepair state of concrete cracks, thereby ensuring the safe service of engineering structures.

[0004] Current concrete crack self-repairing is mainly in conventional environment, and the applicability in marine corrosion environment is insufficient. Marine concrete crack self-repairing not only needs to realize the filling repair of cracks, but also needs to solidify the corrosion ions invading the cracks to avoid the corrosion of concrete materials. SUMMARY

[0005] The purpose of the present application is to provide a concrete crack self-repairing agent suitable for marine corrosion conditions, which can realize complete closure of cracks and inhibit corrosion of concrete.

[0006] Technical scheme: The concrete crack self-repairing agent suitable for marine corrosion conditions comprises component one and component two; the component one and the component two are both core-shell structures;

[0007] The outer shell of the component one is a polymer film; the inner layer comprises the following components in mass percentage: 20-30% barite powder, 50-60% magnesium source, and 20-30% cement;

[0008] The outer shell of the component two is a polymer film; the inner layer comprises the following components in mass percentage: 20-30% barite powder, 5-10% microbial powder, 20-30% glucose, 20-40% aluminum source, and 10-30% low-alkali cement.

[0009] The microorganism powder is a complex bacterial group of acetic acid bacteria and acetic acid oxidizing bacteria, and the number of acetic acid bacteria accounts for 40%-60%.

[0010] The magnesium source is magnesium acetate and / or four-water magnesium acetate.

[0011] The aluminum source is one or more of sodium metaaluminate, active alumina, and aluminum hydroxide.

[0012] The low-alkali cement is a low-alkali cement commonly used in the prior art, such as a sulfoaluminate cement or an aluminate cement.

[0013] The complex ratio of component one and component two is determined according to the molar ratio of the magnesium source and the aluminum source being 1:2.0-2.7.

[0014] The component one and the component two are mixed uniformly according to the ratio, and then a continuous grading spherical particle is prepared, and the particle diameter is 0.15mm-4.70mm.

[0015] The polymer film is realized by being immersed in a polymer solution and dried, and the polymer solution is at least one of a butyl benzene emulsion, a phenyl propyl emulsion, and an acetone benzene emulsion.

[0016] The thickness of the polymer film is 0.2mm-0.5mm.

[0017] The component one and the component two are mixed according to the ratio, and then are mixed into the concrete in the form of replacing the same mass of sand. 3 -2700kg / m 3 , and the loose bulk density is 1400kg / m 3 -1600kg / m 3 .

[0018] The component one and the component two are mixed according to the ratio, and then are mixed into the concrete in the form of replacing the same mass of sand.

[0019] Invention principle: The magnesium source of component one and the aluminum source of component two of the repair agent of the present application will react to form magnesium-aluminum double metal hydroxide under strong alkaline conditions. This reaction will consume hydroxyl ions in the crack solution, reduce the pH of the crack solution, and provide suitable conditions for the growth and reproduction of microorganisms. At the same time, the magnesium-aluminum double metal hydroxide formed will bind a large number of water molecules to expand in volume, quickly reducing the crack water carrying capacity. In addition, the magnesium-aluminum double metal hydroxide formed has a special interlayer structure, which can adsorb and fix the chloride ions and sulfate ions invading the crack, avoiding their corrosive and destructive effects on the concrete. After the pH of the crack area is reduced, the activity of acetic acid bacteria increases, which will decompose glucose in the solution to produce acetic acid and carbon dioxide. Acetic acid can further react with hydroxyl ions in the solution to maintain low alkaline conditions in the crack. Carbon dioxide will also hydrate quickly under alkaline conditions to form carbonate ions, which will combine with calcium ions dissolved from the concrete matrix to form calcium carbonate precipitates. Under the dual action of double metal hydroxide and acetic acid bacteria, the pH of the crack is maintained at a low level, and the activity of acetic acid oxidizing bacteria is greatly increased, which can decompose acetate ions into carbon dioxide. Carbon dioxide will continue to react with alkaline substances in the matrix to form more products and accumulate in the crack space, forming a better sealing effect.

[0020] Beneficial effects: Compared with the prior art, the present application has the following remarkable effects: (1) The present application realizes the filling of the concrete crack space and the solidification of the invading crack corrosion ions through the synergistic effect of microbial mineralization and metal mineral hydration, especially suitable for marine corrosion environment. (2) The repair agent particles are prepared according to continuous particle size, and the same mass replaces fine aggregate, which has little effect on the fineness modulus of fine aggregate and no significant negative effect on the strength of concrete. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The photo of the repair agent of Example 1;

[0022] Figure 2 The crack repair rate of the concrete prepared by the repair agent of Examples 1-3;

[0023] Figure 3 The effect of the repair agent of Example 1 on the mechanical strength of concrete;

[0024] Figure 4 The change of pH and the number of microorganisms in the crack solution of marine concrete under simulated conditions;

[0025] Figure 5 The change of glucose and acetate ions in the crack solution of marine concrete under simulated conditions;

[0026] Figure 6 The change of chloride ions and sulfate ions in the crack solution of marine concrete under simulated conditions;

[0027] Figure 7SEM image of the repair product. DETAILED DESCRIPTION

[0028] The present application is described in further detail below.

[0029] Example 1

[0030] Preparation of component one particles: mixed according to the proportions of 30% barite powder, 50% magnesium acetate, and 20% sulphoaluminate cement. The mixed powder was put into a sugar-coating machine, and the powder and water were alternately added to gradually agglomerate the mixed powder into solid spherical particles. The 0.15-4.7 mm solid spherical particles were sieved out. The outer layer was sprayed with a butyl benzene emulsion, and a polymer film was formed after drying for 2 h, with a thickness of about 0.2 mm.

[0031] Preparation of component two particles: mixed according to the proportions of 20% barite powder, 5% microbial powder, 20% glucose, 35% sodium metaaluminate, and 20% sulphoaluminate cement. The number of acetic acid bacteria in the microbial powder accounted for 40%. The mixed powder was put into a sugar-coating machine, and the powder and water were alternately added to gradually agglomerate the mixed powder into solid spherical particles. The 1.0-4.7 mm solid spherical particles were sieved out. The outer layer was sprayed with a butyl benzene emulsion, and a polymer film was formed after drying for 2 h, with a thickness of about 0.2 mm.

[0032] The apparent density of component one was 2700 kg / m 3 , and the apparent density of component two was 2500 kg / m 3 . Component one and component two were compounded according to a magnesium source to aluminium source molar ratio of 1:2.0. The self-repairing concrete was prepared according to Table 1, and the size of the formed test piece was a φ100 mm x 100 mm cylinder.

[0033] Table 1: Mix proportion of self-repairing concrete

[0034]

[0035] The prepared self-repairing concrete was cured for 28 d under standard conditions. The cured test piece was prepared according to the splitting method to form a crack with a width of about 1.0 mm, and the crack width was fixed. The test piece with the crack was cured for 28 d under simulated seawater conditions, and the crack area repair rate was tested. Figure 1 The photo of the repair agent of Example 1 shows that the repair agent particles have a spherical shape, and the inside is a core-shell structure, which can provide sufficient loading space for the repair component. At the same time, the circular shape structure makes the repair agent added to the concrete not produce large stress concentration, avoids becoming a weak point of the concrete, and reduces the mechanical strength of the concrete.

[0036] Example 2

[0037] Component one: 20% barite powder, 60% magnesium acetate, 20% aluminate cement were mixed to prepare 0.15mm-4.7mm solid pellet particles. The outer layer was sprayed with styrene-acrylic emulsion, and a polymer film was formed after drying for 2h. The spraying and drying were repeated until the film thickness was about 0.5mm.

[0038] Component two: 30% barite powder, 10% microbial powder, 30% glucose, 20% sodium metaaluminate, 10% aluminate cement were mixed to prepare 0.15mm-4.7mm solid pellet particles. The number of acetate bacteria in the microbial powder accounted for 60%. The outer layer was sprayed with styrene-acrylic emulsion, and a polymer film was formed after drying for 2h. The spraying and drying were repeated until the film thickness was about 0.5mm.

[0039] The apparent density of component one was 2500kg / m 3 , and the apparent density of component two was 2700kg / m 3 . Component one and component two were compounded according to a magnesium source to aluminum source molar ratio of 1:2.7. The self-repairing concrete was prepared according to Table 1, and the molded test piece size was a φ100mm×100mm cylinder.

[0040] The prepared self-repairing concrete was cured for 28d under standard conditions. The cured test piece was prepared according to the splitting method to have a crack width of about 1.0mm, and the crack width was fixed. The test piece with the crack was cured for 28d under simulated seawater conditions, and the crack area repair rate was tested.

[0041] Example 3

[0042] Component one: 20% barite powder, 50% magnesium acetate tetrahydrate, 30% aluminate cement were mixed to prepare 0.15mm-4.7mm solid pellet particles. The outer layer was sprayed with vinyl acetate styrene emulsion, and a polymer film was formed after drying for 2h, with a thickness of about 0.2mm.

[0043] Component two: 20% barite powder, 5% microbial powder, 25% glucose, 40% aluminum hydroxide, 10% aluminate cement were mixed to prepare 0.15mm-4.7mm solid pellet particles. The number of acetate bacteria in the microbial powder accounted for 40%. The outer layer was sprayed with vinyl acetate styrene emulsion, and a polymer film was formed after drying for 2h, with a thickness of about 0.2mm.

[0044] Component one and component two were compounded according to a magnesium source to aluminum source molar ratio of 1:2.0. The self-repairing concrete was prepared according to Table 1, and the molded test piece size was a φ100mm×100mm cylinder.

[0045] The prepared self-healing concrete was cured under standard conditions for 28 days. After curing, cracks approximately 1.0 mm wide were created in the specimens using a splitting method, and the crack width was fixed. The cracked specimens were then cured for 28 days in simulated seawater conditions, and the crack area repair rate was measured.

[0046] Figure 2 The repair ability of the repair agents prepared in Examples 1-3 shows that the crack repair rates of the three examples all reach 95%, and the repair effect is good, indicating that the repair agents prepared with the above ratios can better achieve efficient repair of concrete cracks and basically achieve complete closure of the cracks.

[0047] Self-healing concrete was prepared using the repair agent prepared in Example 1 according to Table 2, with the repair agent replacing 1%-5% of the fine aggregate by mass. Concrete specimens were 100 mm × 100 mm × 100 mm cubes. The formed specimens were cured under standard conditions for 28 days before compressive strength testing.

[0048] Table 2 Concrete mix ratio

[0049]

[0050] like Figure 3 As shown in the figure, there is no significant decrease in the compressive strength of concrete, indicating that the addition of the repair agent has no negative effect on the mechanical properties of concrete.

[0051] Simulated seawater was prepared at a ratio of 4.53 g / L NaCl₂, 5.20 g / L Mg₂Cl₂, 4.09 g / L Na₂SO₄, 1.16 g / L CaCl₂, and 0.695 g / L KCl. Ordinary Portland cement was mixed with simulated seawater at a ratio of 1:10. After standing for 24 hours, the supernatant was collected to prepare a simulated solution for marine concrete cracks. Components 1 and 2, prepared in Example 1, were mixed in appropriate proportions and ground into powder. The repair agent particles were mixed with the marine concrete crack solution at a ratio of 1:5. The crack solution was then tested for pH, microbial population changes, and glucose concentration.

[0052] like Figure 4 As shown in the figure, after the addition of the repair agent, the pH of the solution gradually decreased and stabilized to about 10.2. The pH of the solution stabilized at a low alkaline level, and the number of microorganisms in the solution began to gradually increase. It can be seen that the OD 600 The curve gradually increases to about 1.8, indicating that a large number of microorganisms appear in the solution. Figure 5As shown, the glucose concentration gradually decreased with the increase of microbial population, indicating that glucose was consumed. With the degradation of grape, acetate ions gradually appeared and gradually disappeared after reaching a certain concentration, indicating that when acetobacter was active, glucose was decomposed into acetic acid molecules. A large amount of acetate could not be consumed by acetic acid oxidizing bacteria in time, resulting in accumulation. With the gradual increase of acetic acid oxidizing bacteria, acetic acid molecules were gradually decomposed. Figure 6 As shown, the concentrations of chloride ions and sulfate ions rapidly decreased to stable at the early stage of the reaction, indicating that the chloride ions and sulfate ions were adsorbed and fixed, and also indicating that the harm to concrete that they might bring was limited. Figure 7 For the SEM image of the repair product, it can be seen that the repair product densely fills the crack space.

Claims

1. A concrete crack self-repairing agent suitable for marine corrosion conditions, characterized by, It comprises component one and component two; both of the component one and the component two are core-shell structure; The outer shell of the component one is polymer film; the inner layer comprises the following components in percentage by mass: 20-30% barite powder, 50%-60% magnesium source, 20%-30% cement; The outer shell of the component two is polymer film; the inner layer comprises the following components in percentage by mass: 20-30% barite powder, 5-10% microbial powder, 20-30% glucose, 20%-40% aluminum source, 10%-30% low-alkali cement.

2. The concrete crack self-repairing agent suitable for marine corrosion conditions according to claim 1, characterized by, The microbial powder is a composite bacterial group of acetic acid bacteria and acetic acid oxidizing bacteria, and the proportion of acetic acid bacteria in the composite bacterial group is 40%-60%.

3. The concrete crack self-repairing agent suitable for marine corrosion conditions according to claim 1, characterized by, The magnesium source is magnesium acetate and / or magnesium acetate tetrahydrate.

4. The concrete crack self-repairing agent suitable for marine corrosion conditions according to claim 1, characterized by, The aluminum source is one or more of sodium metaaluminate, active alumina and aluminum hydroxide.

5. The concrete crack self-repairing agent suitable for marine corrosive conditions according to claim 1, characterized in that, The mixing ratio of the component one and the component two is determined according to the molar ratio of the magnesium source and the aluminum source being 1:2.0-2.

7.

6. The concrete crack self-repairing agent suitable for marine corrosive conditions according to claim 1, characterized by, The component one and the component two are mixed uniformly according to the ratio and then made into continuously graded spherical particles with a particle diameter of 0.15mm-4.70mm.

7. The concrete crack self-repairing agent suitable for marine corrosive conditions according to claim 1, characterized by, The polymer film is realized by dipping in a polymer solution and drying, and the polymer solution is at least one of butyl benzene emulsion, phenylpropyl emulsion and acetone benzene emulsion.

8. The concrete crack self-repairing agent suitable for marine corrosive conditions according to claim 1, characterized by, The thickness of the polymer film is 0.2mm-0.5mm.

9. The concrete crack self-repairing agent suitable for marine corrosive conditions according to claim 1, characterized in that, Component one and component two granules have apparent densities of 2500 kg / m 3 -2700 kg / m 3 , respectively, and bulk densities of 1400 kg / m 3 -1600 kg / m 3 , respectively.

10. The concrete crack self-repairing agent suitable for marine corrosive conditions according to claim 1, characterized in that, The component one and the component two are mixed according to the ratio and then mixed into concrete in the form of replacing sand with the same mass.

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