CRACK SELF-HEALING AGENT FOR CEMENT-BASED MATERIALS CAPABLE OF BINDING CORROSIVE IONS IN SEAWATER, AND PREPARATION METHOD THEREOF

Abstract

Disclosed are a crack self-healing agent for cement-based materials capable of binding corrosive ions in seawater, and a preparation method thereof. A core material of the agent is an active inorganic composite component capable of chemically binding Cl, Mg, and S, a wall layer is polymethyl methacrylate, and an interface improvement layer is a cement layer. A preparation method includes: (1) thoroughly mixing active components capable of binding corrosive ions, and filling a resulting mixture into a direct compression mold; (2) applying a pressure to the direct compression mold and holding the pressure on using a pressing machine, and demolding to obtain a core material body; (3) placing the core material body obtained in a solution of PMMA in acetone for coating, and taking out the core material body and drying; (4) coating a layer of cement before the acetone is completely volatilized to obtain the crack self-healing agent.

Claims

1. A crack self-healing agent for cement-based materials capable of binding corrosive ions in seawater, comprising an active component core material capable of binding corrosive ions, a wall layer, and an interface improvement layer, wherein the active component core material capable of binding corrosive ions is a mixture of a calcium-containing inorganic substance, an aluminum-containing inorganic substance, and a macromolecule water-absorbent resin; the wall layer is a polymethyl methacrylate (PMMA) layer, which covers the active component core material capable of binding corrosive ions; and the interface improvement layer is a cement layer.

2. The crack self-healing agent for cement-based materials capable of binding corrosive ions in seawater according to claim 1, wherein a molar ratio of the calcium-containing inorganic substance to the aluminum-containing inorganic substance is (3-5):1; and a weight of the macromolecule water-absorbent resin is 0% to 10% of a total weight of the calcium-containing inorganic substance and the aluminum-containing inorganic substance.

3. The crack self-healing agent for cement-based materials capable of binding corrosive ions in seawater according to claim 1, wherein the calcium-containing inorganic substance comprises one or more from the group consisting of calcium oxide and calcium hydroxide; and the aluminum-containing inorganic substance comprises one or more from the group consisting of sodium metaaluminate and metakaolin.

4. The crack self-healing agent for cement-based materials capable of binding corrosive ions in seawater according to claim 1, wherein the crack self-healing agent has a particle size of 4 mm to 8 mm.

5. A preparation method of the crack self-healing agent for cement-based materials capable of binding corrosive ions in seawater according to claim 1, comprising the following steps: (1) thoroughly mixing active components capable of binding corrosive ions, and filling a resulting mixture into a direct compression mold; (2) applying a pressure to the direct compression mold and holding the pressure on using a pressing machine, and demolding to obtain a core material body; (3) placing the core material body obtained in a solution of PMMA in acetone for coating, and taking out the core material body and drying; and (4) coating a layer of cement before the acetone is completely volatilized to obtain the crack self-healing agent for cement-based materials capable of binding corrosive ions in seawater.

6. The preparation method according to claim 5, wherein in step (2), a pressure of 250 psi to 750 psi is applied.

7. The preparation method according to claim 5, wherein in step (2), a pressure of 250 psi to 750 psi is held for 30 s to 60 s.

8. The preparation method according to claim 5, wherein in step (3), the solution of PMMA in acetone has a concentration of 0.2 g/mL to 0.3 g/mL.

9. The preparation method according to claim 5, wherein in step (3), the process of placing the core material body obtained in a solution of PMMA in acetone for coating and taking out the core material body and drying is repeated 3 to 6 times.

10. A method for crack self-healing and steel bar protection in marine concrete, comprising: using the crack self-healing agent for cement-based materials capable of binding corrosive ions in seawater according to claim 1.

11. A method for crack self-healing and steel bar protection in marine concrete, comprising: using the crack self-healing agent for cement-based materials capable of binding corrosive ions in seawater according to claim 2.

12. A method for crack self-healing and steel bar protection in marine concrete, comprising: using the crack self-healing agent for cement-based materials capable of binding corrosive ions in seawater according to claim 3.

13. A method for crack self-healing and steel bar protection in marine concrete, comprising: using the crack self-healing agent for cement-based materials capable of binding corrosive ions in seawater according to claim 4.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0034] FIG. 1 is a schematic diagram of the core material prepared in the present disclosure;

[0035] FIG. 2 is a schematic diagram of the cement self-healing agent capable of binding corrosive ions prepared in the present disclosure;

[0036] FIG. 3 shows a crack healing rate curve of the self-healing cement paste prepared in Example 1 of the present disclosure; and

[0037] FIG. 4 shows an open circuit potential (OCP) curve of a steel bar in the self-healing cement paste prepared in Example 2 of the present disclosure.

DETAILED DESCRIPTION

[0038] The technical solutions of the present disclosure will be further described in detail below in conjunction with specific examples and accompanying drawings, but the protection scope and implementation manners of the present disclosure are not limited thereto.

[0039] In a specific embodiment of the present disclosure, the calcium oxide used is analytically pure, with a particle size of 200 mesh; the sodium metaaluminate used is analytically pure, with a particle size of 200 mesh; the metakaolin used is commercially pure, with a particle size of 3 μm; and the macromolecule water-absorbent resin used is commercially pure, with a particle size of 50 mesh to 60 mesh.

[0040] The crack self-healing agent for cement-based materials capable of binding corrosive ions in seawater provided in the present disclosure includes an active component core material capable of binding corrosive ions, a wall layer, and an interface improvement layer, where the active component core material capable of binding corrosive ions is a mixture of a calcium-containing inorganic substance, an aluminum-containing inorganic substance, and a macromolecule water-absorbent resin; the wall layer is a PMMA layer, which covers the active component core material capable of binding corrosive ions; and the interface improvement layer is a cement layer. A molar ratio of the calcium-containing inorganic substance to the aluminum-containing inorganic substance may be (3-5):1; a weight of the macromolecule water-absorbent resin may be 0% to 10% of a total weight of the calcium-containing inorganic substance and the aluminum-containing inorganic substance; and the calcium-containing inorganic substance may be calcium oxide, and the aluminum-containing inorganic substance may be sodium metaaluminate. The crack self-healing agent may have a particle size of 5 mm to 7 mm.

Example 1

[0041] A crack self-healing agent for cement-based materials capable of binding corrosive ions in seawater was provided, and a preparation method thereof specifically included the following steps:

[0042] (1) Calcium oxide, sodium metaaluminate, and low cross-linked sodium polyacrylate (macromolecule water-absorbent resin) were adopted as active components capable of binding corrosive ions, 10 g of calcium oxide, 5 g of sodium metaaluminate, and 1.5 g of low cross-linked sodium polyacrylate were each weighed and thoroughly mixed in a V-type mixer, an appropriate amount of a resulting mixture was filled into a direct compression mold, and the mold was assembled.

[0043] (2) A pressure of 750 psi was applied to the direct compression mold using a pressing machine and held for 30 s, and then demolding was conducted to obtain a core material, as shown in FIG. 1.

[0044] (3) The core material was immersed in a solution of 0.2 g/mL PMMA in acetone, then taken out after a surface of the core material was completely wetted, and then dried in a fume hood until the acetone was completely volatilized. The immersion and drying process was repeated 6 times. Before the acetone was completely volatilized the last time, a layer of cement powder was coated on the surface to finally obtain the crack self-healing agent with a size of 6 t 1 mm, as shown in FIG. 2.

[0045] (4) The crack self-healing agent was added to a cement paste at 5% of a volume of the cement paste. As shown in FIG. 3, when a hardened cement paste cracks, the crack self-healing agent enables cement test blocks to quickly block cracks of 0.4 mm, which can effectively prevent environmental corrosive ions from entering an interior of a matrix.

Example 2

[0046] A crack self-healing agent for cement-based materials capable of binding corrosive ions in seawater was provided, and a preparation method thereof specifically included the following steps:

[0047] (1) Calcium oxide, metakaolin, and low cross-linked sodium polyacrylate (macromolecule water-absorbent resin) were adopted as active components capable of binding corrosive ions, 16 g of calcium oxide, 6 g of metakaolin, and 1.1 g of low cross-linked sodium polyacrylate were each weighed and thoroughly mixed in a V-type mixer, an appropriate amount of a resulting mixture was filled into a direct compression mold, and the mold was assembled.

[0048] (2) A pressure of 250 psi was applied to the direct compression mold using a pressing machine and held for 60 s, and then demolding was conducted to obtain a core material, as shown in FIG. 1.

[0049] (3) The core material was immersed in a solution of 0.3 g/mL PMMA in acetone, then taken out after a surface of the core material was completely wetted, and then dried in a fume hood until the acetone was completely volatilized. The immersion and drying process was repeated 3 times. Before the acetone was completely volatilized the last time, a layer of cement powder was coated on the surface to finally obtain the crack self-healing agent with a size of 6±1 mm, as shown in FIG. 2.

[0050] (4) The crack self-healing agent was added to a cement paste at 8% of a volume of the cement paste. As shown in FIG. 4, when a hardened cement paste cracks, the crack self-healing agent can effectively reduce an OCP of steel bars in the matrix, which reduces the possibility of steel bar corrosion and shows some degree of reinforcement.

[0051] The examples above are preferred implementations of the present disclosure. However, the implementations of the present disclosure are not limited by the examples above. Any change, modification, substitution, combination, and simplification made without departing from the spiritual essence and principle of the present disclosure should be an equivalent replacement manner, and all are included in the protection scope of the present disclosure.