Low-shrinkage high-strength self-healing concrete and preparation method thereof

Abstract

This invention relates to a low-shrinkage, high-strength, self-healing concrete and its preparation method, comprising: Step 1, mixing 2-4 parts of penetrating crystalline waterproofing agent and 100-200 parts of water evenly to obtain solution A; Step 2, mixing 6-20 parts of nano-silica and 3-4 parts of water-reducing agent and ultrasonically dispersing the mixture to obtain suspension B; Step 3, compounding 140-280 parts of iron tailings sand and 700-800 parts of river sand; then mixing the compounded iron tailings sand and river sand with 600-700 parts of coarse aggregate, 300-400 parts of cement and 100-150 parts of fly ash evenly to obtain dry mix C; Step 4, adding solution A to dry mix C and stirring evenly to obtain slurry D; Step 5, adding suspension B to slurry D and stirring evenly to obtain slurry E; Step 6, adding 7-18 parts of expanding agent to slurry E and stirring evenly to obtain low-shrinkage, high-strength, self-healing concrete. The concrete of this invention not only ensures stable and dense concrete volume and maintains good mechanical properties, but also possesses excellent self-healing properties for cracks.

Description

Technical Field

[0001] This invention relates to the field of building materials, specifically to a low-shrinkage, high-strength self-healing concrete and its preparation method. Background Technology

[0002] In current projects, it has been found that high-strength concrete, due to the high amount of gelling materials, low water-cement ratio, and continuous evaporation of internal moisture in the later stages, is prone to increased shrinkage, causing volume changes, resulting in cracks in the concrete, increasing the instability of the concrete structure, and posing a risk of damage.

[0003] Traditional methods for repairing concrete cracks can be divided into two types: passive repair and active repair.

[0004] Passive repair refers to artificial repair after concrete cracks have occurred. This type of repair is delayed, and the repair process can cause new environmental pollution and lead to problems with the incompatibility between organic components and concrete components.

[0005] Active repair is a self-healing behavior that actively detects and repairs cracks, and has advantages such as high repair efficiency, economy and environmental protection.

[0006] Compared to passive repair, active repair has the advantage of pre-repair, which can prevent concrete cracks from being discovered only after they have become large. It can continuously repair itself during the cracking process, thus avoiding potential safety hazards to the concrete structure.

[0007] Based on this, the present invention proposes a low-shrinkage, high-strength self-healing concrete and its preparation method. This concrete ensures stable and dense concrete volume and maintains good mechanical properties, while also possessing excellent crack self-healing properties. Summary of the Invention

[0008] To achieve the above-mentioned technical objectives, the present invention provides a low-shrinkage, high-strength self-healing concrete and its preparation method. The technical objectives of the present invention are achieved through the following technical solutions:

[0009] A low-shrinkage, high-strength, self-healing concrete comprises the following materials in parts by weight: 300-400 parts cement, 6-20 parts nano-silica, 100-150 parts fly ash, 700-800 parts river sand, 140-280 parts iron tailings sand, 600-700 parts coarse aggregate, 3-4 parts water-reducing agent, 2-4 parts penetrating crystalline waterproofing agent, 7-18 parts expansion agent, and 100-200 parts water.

[0010] Furthermore, the penetrating crystalline waterproofing agent comprises a precipitating agent, a complex, and a calcium ion compensator mixed in a weight ratio of 3:2:5.

[0011] Furthermore, penetrating crystalline waterproofing agents also include surfactants, which account for 0.1%-1% of the total content.

[0012] Furthermore, the precipitation reaction agent is a mixture of sodium silicate, sodium carbonate and potassium phosphate, with a weight ratio of 6-8:3-4:1-2.

[0013] Furthermore, the complex is a mixture of potassium sodium tartrate and sodium gluconate, wherein the weight ratio of potassium sodium tartrate to sodium gluconate does not exceed 35:1.

[0014] Furthermore, the calcium ion compensator is a mixture of calcium acetate and calcium hydroxide, with a weight ratio of 3:7.

[0015] Furthermore, the surfactant is hexadecyltrimethylammonium bromide.

[0016] Furthermore, the expanding agent includes calcium oxide, sulfur trioxide, and silicon dioxide, with the calcium oxide content being 50%-70%, the sulfur trioxide content being 10%-20%, and the silicon dioxide content being 3%-10%.

[0017] Furthermore, the expanding agent is a solid powder with a density of 2.85 g / cm³. 3 Specific surface area is 336 m² 2 / kg.

[0018] Furthermore, the purity of the nano-silica is greater than 98%, the particle size is 6-30 nm, and the specific surface area is 300 m². 2 The refractive index is not less than 1.45%.

[0019] Furthermore, the fineness modulus of the river sand is 2.6, and the bulk density is 1410 kg / m³. 3 The apparent density is 2763 kg / m³. 3 It contains 1.9% stone powder and has a water absorption rate of 1.3%.

[0020] Furthermore, the iron tailings sand has a silica content greater than 75%, a fineness modulus of 2.5, and a bulk density of 1398 kg / m³. 3 Apparent density 2650 kg / m³ 3 It contains 1.8% stone powder and has a water absorption rate of 4.6%.

[0021] Furthermore, the coarse aggregate is one or a mixture of two types of continuously graded basalt, granite, gneiss, and andesite crushed stone with a particle size of 5-20 mm, a crushing index of 5.5%, and a bulk density of 1410 kg / m³. 3 .

[0022] Furthermore, the fly ash is classified as secondary fly ash, containing 0.45% sulfur trioxide and having a specific surface area of ​​570 m². 2 / kg, water requirement 92%, loss on ignition 4.2%.

[0023] Furthermore, the cement is P.II52.5 silicate cement, and the total mass percentage of silica, calcium oxide, and alumina in the cement is not less than 80%, with a specific surface area of ​​385 m². 2 / g, apparent density is 3010kg / m³ 3 28-day strength ≥ 55 MPa.

[0024] Furthermore, the water-reducing agent is a composite polycarboxylate high-efficiency water-reducing agent with a molecular topological structure, a water reduction rate of >25%, and a solid content of 20%±2%.

[0025] This invention also provides a method for preparing low-shrinkage, high-strength, self-healing concrete, wherein the raw materials are measured according to the weight ratio, and the method includes the following steps:

[0026] Step 1: Mix the penetrating crystalline waterproofing agent and water until homogeneous to obtain solution A;

[0027] Step 2: Mix nano-silica and water-reducing agent and disperse by ultrasonication to obtain suspension B;

[0028] Step 3: Mix the iron tailings sand and river sand to a fineness modulus of 2.2-2.6, and the porosity of the mixed material is less than 40%; then mix the mixed iron tailings sand, river sand, coarse aggregate, cement and fly ash evenly to obtain dry mix C.

[0029] Step 4: Add solution A to dry mixture C and stir until homogeneous to obtain slurry D;

[0030] Step 5: Add suspension B to slurry D and stir evenly to obtain slurry E;

[0031] Step 6: Add the expansion agent to slurry E and stir evenly to obtain low-shrinkage, high-strength, self-healing concrete.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] 1. The nano-silica used in this invention has nano-size and high pozzolanic activity. When used in combination with fly ash, it can exert the pozzolanic effect more efficiently. At the same time, it consumes calcium hydroxide crystals, generates more CSH gel, refines hydration products, improves the interface transition zone, reduces total porosity and critical porosity, making the structure more compact and improving the volume stability of concrete. Nano-silica can promote crystal nucleation and crystal growth in cementitious materials, increase the hydration reaction rate, and improve the early strength and durability of cementitious materials.

[0034] 2. In this invention, the CSH gel structure generated by the hydration of iron tailings sand results in a uniform distribution of hydration products encapsulated in the gel material. These hydration products interconnect, filling cracks and pores in the transition zone between aggregate and mortar, reducing harmful pores in the microstructure and further optimizing the pore structure. Furthermore, the loose and porous microstructure of the iron tailings sand itself can also act as a carrier, adsorbing and uniformly distributing the active chemical substances in the penetrating crystalline waterproofing agent within the cementitious substrate. The rational utilization of tailings sand not only reduces the accumulation of iron tailings sand and protects the ecological environment but also reduces the consumption of building materials, actively responding to the dual-carbon policy and lowering the economic cost of engineering projects.

[0035] 3. The penetrating crystalline waterproofing agent in this invention is composed of a variety of active substances, and the precipitation reaction agent in the cement is Ca. 2+ Precipitates such as CSH, calcium carbonate, calcium silicate, and calcium phosphate are formed. Calcium hydroxide, a calcium ion compensator, is alkaline; using only calcium hydroxide will cause a strong alkaline reaction in cementitious materials, inhibiting the hydration process. Calcium acetate, however, is weakly acidic and provides the necessary CaO for precipitate formation. 2+ In addition, it can neutralize alkalinity, ensuring the normal hydration of cement-based materials. Both provide Ca... 2+ Ca inside and outside the concrete 2+ The concentration difference and osmotic pressure facilitate the penetration of carbonate ions, thereby generating more crystals.

[0036] 4. The cetyltrimethylammonium bromide in the penetrating crystalline waterproofing agent of this invention has good surface stability, which is beneficial to improving the homogeneity of the overall active material of the penetrating crystalline waterproofing agent, and it remains stable in strong alkali.

[0037] 5. When cracks appear in concrete, the penetrating crystallizer reacts with Ca... 2+ The reaction produces insoluble white crystals that can immediately, repeatedly, and actively target and fill cracks smaller than 0.5mm, eliminating the need for manual passive repair after cracks appear, saving costs, and improving the safety and service life of concrete.

[0038] 6. The concrete components of this invention are rationally blended and tightly packed, achieving ideal mechanical properties. The composite polycarboxylate high-efficiency water-reducing agent used has a molecular topological structure, which reduces the frictional resistance between aggregates inside the concrete, improves the adsorption of cement particles, reduces the viscosity of the concrete, promotes the dispersion of the paste, facilitates the fusion and uniform distribution of the concrete components with the penetrating crystallizer, and plays an auxiliary role in the self-healing of the concrete. Attached Figure Description

[0039] Figure 1This is a schematic diagram of the cracks caused by the three-point bending failure of concrete in Embodiment 2 of the present invention.

[0040] Figure 2 This is a schematic diagram of the self-healing of concrete cracks after 28 days of curing, according to Embodiment 2 of the present invention.

[0041] Figure 3 This is a schematic diagram of the cracks caused by the three-point bending failure of concrete in Comparative Example 5 of the present invention.

[0042] Figure 4 This is a schematic diagram of the self-healing of concrete cracks after 28 days of curing in Comparative Example 5 of this invention.

[0043] Figure 5 This is a schematic diagram of the process for preparing low-shrinkage, high-strength, self-healing concrete according to the present invention. Detailed Implementation

[0044] The technical solution of the present invention will be further described below with reference to specific embodiments:

[0045] A low-shrinkage, high-strength, self-healing concrete comprises the following materials in parts by weight: 300-400 parts cement, 6-20 parts nano-silica, 100-150 parts fly ash, 700-800 parts river sand, 140-280 parts iron tailings sand, 600-700 parts coarse aggregate, 3-4 parts water-reducing agent, 2-4 parts penetrating crystalline waterproofing agent, 7-18 parts expansion agent, and 100-200 parts water.

[0046] The penetrating crystalline waterproofing agent comprises a precipitating agent, a complexing agent, and a calcium ion compensator mixed in a weight ratio of 3:2:5. The penetrating crystalline waterproofing agent also includes a surfactant, which accounts for 0.1%-1% of the total content. The surfactant is hexadecyltrimethylammonium bromide, which contributes to the homogeneity of the overall active material in the penetrating crystalline waterproofing agent. The precipitating agent is a mixture of sodium silicate, sodium carbonate, and potassium phosphate, with a weight ratio of 6-8:3-4:1-2. The complexing agent is a mixture of sodium potassium tartrate and sodium gluconate, with a weight ratio not exceeding 35:1. The calcium ion compensator is a mixture of calcium acetate and calcium hydroxide, with a weight ratio of 3:7. To better understand this invention, a set of example data is provided below:

[0047] The added penetrating crystalline waterproofing agent is 100 kg, and the surfactant content is 1%, which means it contains 1 kg of surfactant. The remaining 99% is a precipitating agent, complexing agent, and calcium ion compensator prepared in a 3:2:5 weight ratio: 29.7 kg of precipitating agent, 19.8 kg of complexing agent, and 49.5 kg of calcium ion compensator. In the precipitating agent, sodium silicate, sodium carbonate, and potassium phosphate are mixed in a 6:3:1 ratio: 17.82 kg of sodium silicate, 8.91 kg of sodium carbonate, and 2.97 kg of potassium phosphate. The ratio of sodium potassium tartrate to sodium gluconate does not exceed 35:1, which means the maximum content of sodium potassium tartrate is 19.25 kg. Calcium acetate and calcium hydroxide are 14.85 kg and 34.65 kg, respectively.

[0048] The expanding agent is a calcium oxide-based expanding agent; it is a white solid powder with a density of 2.85 g / cm³. 3 Specific surface area is 336 m² 2 / kg. The expanding agent includes calcium oxide, sulfur trioxide, and silicon dioxide, with calcium oxide content of 50%-70%, sulfur trioxide content of 10%-20%, and silicon dioxide content of 3%-10%.

[0049] The purity of the nano-silica is greater than 98%, the particle size is 6-30 nm, and the specific surface area is 300 m². 2 The refractive index is not less than 1.45%.

[0050] The fineness modulus of the river sand is 2.6, and the bulk density is 1410 kg / m³. 3 The apparent density is 2763 kg / m³. 3 It contains 1.9% stone powder and has a water absorption rate of 1.3%.

[0051] The iron tailings sand has a silica content greater than 75%, a fineness modulus of 2.5, and a bulk density of 1398 kg / m³. 3 Apparent density 2650 kg / m³ 3 The stone powder content is 1.8%, the water absorption rate is 4.6%, and the toxicity of the leachate from the iron tailings sand needs to meet the requirements for solid waste.

[0052] The coarse aggregate is one or a combination of two of the following continuously graded basalt crushed stone, granite crushed stone, gneiss crushed stone, and andesite crushed stone with a particle size of 5-20 mm, a crushing index of 5.5%, and a bulk density of 1410 kg / m³. 3 .

[0053] The fly ash is classified as Grade II fly ash, containing 0.45% sulfur trioxide and having a specific surface area of ​​570 m². 2 / kg, water requirement 92%, loss on ignition 4.2%.

[0054] The cement is P.II52.5 silicate cement, and the total mass percentage of silica, calcium oxide, and alumina in the cement is not less than 80%. The specific surface area of ​​the cement is 385 m². 2 / g, apparent density is 3010kg / m³ 3 28-day strength ≥ 55 MPa.

[0055] The water-reducing agent is a composite polycarboxylate high-efficiency water-reducing agent with a molecular topological structure, a water reduction rate of >25%, and a solid content of 20%±2%.

[0056] This embodiment also provides a method for preparing low-shrinkage, high-strength, self-healing concrete, wherein the raw materials are measured according to the weight ratios in the above embodiments, such as... Figure 5 As shown, the method includes the following steps:

[0057] Step 1: Mix the penetrating crystalline waterproofing agent and water until homogeneous to obtain solution A;

[0058] Step 2: Mix nano-silica and water-reducing agent and disperse by ultrasonication to obtain suspension B;

[0059] Step 3: Mix iron tailings sand and river sand to a fineness modulus of 2.2-2.6, and the porosity of the mixed material is less than 40%; then mix the mixed iron tailings sand, river sand, coarse aggregate, cement and fly ash evenly to obtain dry mix C.

[0060] Step 4: Add solution A to dry mixture C and stir until homogeneous to obtain slurry D;

[0061] Step 5: Add suspension B to slurry D and stir evenly to obtain slurry E;

[0062] Step 6: Add the expansion agent to slurry E and stir evenly to obtain low-shrinkage, high-strength, self-healing concrete.

[0063] To better understand the present invention, the following embodiments and comparative examples are provided:

[0064] Example 1

[0065] A low-shrinkage, high-strength, self-healing concrete is prepared by the following method:

[0066] Step 1: Mix 2.2 parts of penetrating crystalline waterproofing agent and 140 parts of water in a magnetic stirrer and stir at 400 rpm for 2 minutes until the mixture is homogeneous to obtain solution A.

[0067] Step 2: Mix 11 parts of nano silica and 3.6 parts of water-reducing agent and disperse them by ultrasonication at a frequency of 55 kHz, a power of 130 W, and a duration of 4 min to obtain suspension B for later use.

[0068] Step 3: Mix 240 parts iron tailings sand, 700 parts coarse aggregate, 350 parts cement, 730 parts river sand and 120 parts fly ash in a mixer for 2 minutes to obtain dry mix C.

[0069] Step 4: Add solution A to dry mixture C and stir until homogeneous to obtain slurry D;

[0070] Step 5: Add suspension B to slurry D and stir evenly to obtain slurry E;

[0071] Step 6: Add the expansion agent to slurry E and stir evenly to obtain low-shrinkage, high-strength, self-healing concrete.

[0072] Example 2

[0073] The concrete samples from Example 1, after 28 days of curing, were subjected to three-point bending failure, resulting in cracks of 0.1-0.5 mm.

[0074] Comparative Example 1

[0075] A low-shrinkage, high-strength, self-healing concrete is made by replacing the fly ash in Example 1 with an equal amount of cement.

[0076] Comparative Example 2

[0077] A low-shrinkage, high-strength, self-healing concrete differs from Example 1 in that it does not contain nano-silica.

[0078] Comparative Example 3

[0079] A low-shrinkage, high-strength, self-healing concrete differs from Example 1 in that it does not contain an expansion agent.

[0080] Comparative Example 4

[0081] A low-shrinkage, high-strength, self-healing concrete differs from Example 1 in that an equal amount of iron tailings sand is replaced with river sand.

[0082] Comparative Example 5

[0083] A low-shrinkage, high-strength self-healing concrete differs from Example 2 in that it does not contain a penetrating crystalline waterproofing agent.

[0084] For a clearer comparison, the component proportions of each concrete in Examples 1-2 and Comparative Examples 1-5 are summarized in Table 1:

[0085]

[0086]

[0087] Shrinkage (drying shrinkage) values ​​were tested on the samples of Examples 1-2 and Comparative Examples 1-5 after 28 days of curing. Three-point bending tests were performed on the samples of Example 2 and Comparative Example 5 to create cracks of 0.1-0.5 mm. The repair rate was tested after 28 days, as shown in Table 2.

[0088]

[0089] As can be seen from Table 2:

[0090] Compared with Comparative Example 1, Comparative Example 1 lacked fly ash. The shrinkage value of concrete in Comparative Example 1 after 28 days of curing was greater than that of concrete in Example 1 after 28 days of curing. Fly ash can improve the strength of concrete and inhibit the drying shrinkage of concrete.

[0091] Compared with Example 1, no nano-silica was added in Comparative Example 2. The shrinkage value of the concrete in Comparative Example 2 after 28 days of curing was greater than that of the concrete in Example 1 after 28 days of curing. Nano-silica can improve the strength of concrete and inhibit the drying shrinkage of concrete.

[0092] Compared with Example 1, no expansive agent was added in Comparative Example 3. The shrinkage value of the concrete in Comparative Example 3 after 28 days of curing was greater than that of the concrete in Example 1 after 28 days of curing. The expansive agent can improve the strength of concrete and inhibit the drying shrinkage of concrete.

[0093] Compared with Example 1, no iron tailings sand was added in Comparative Example 4. The shrinkage value of the concrete in Comparative Example 4 after 28 days of curing was greater than that of the concrete in Example 1 after 28 days of curing. Iron tailings sand can improve the strength of concrete and inhibit the drying shrinkage of concrete.

[0094] Compared to Example 2, Comparative Example 5 did not contain a penetrating crystalline waterproofing agent. The shrinkage rate of the concrete in Comparative Example 5 after 28 days of curing was higher than that of the concrete in Example 2 after 28 days of curing. Three-point bending failure tests were performed after 28 days of curing, and the cracking of the concrete in Comparative Example 5 and Comparative Example 2 was examined after another 28 days of curing. Figures 1-4 As shown, Figure 1 The cracks that appeared after the concrete underwent three-point bending failure in Example 2 were completely and automatically healed after 28 days of curing. The healing process was as follows: Figure 2 As shown; Example 3 shows the cracks generated after the concrete underwent three-point bending failure in Comparative Example 5. After 28 days of curing, the cracks also spontaneously healed, but not completely. The healing situation is as follows. Figure 4 As shown in Example 2 and Comparative Example 5, the addition of penetrating crystalline waterproofing agent can improve the strength of concrete, inhibit the drying shrinkage of concrete, and accelerate the self-healing effect of cracks.

[0095] This embodiment is merely a further explanation of the present invention and is not intended to limit the present invention. Those skilled in the art can make non-inventive modifications to this embodiment as needed after reading this specification, but such modifications are protected by patent law as long as they are within the scope of the claims of the present invention.

Claims

1. A low-shrinkage, high-strength, self-healing concrete, characterized in that, The materials are configured according to the following weight parts: 300-400 parts cement, 6-20 parts nano silica, 100-150 parts fly ash, 700-800 parts river sand, 140-280 parts iron tailings sand, 600-700 parts coarse aggregate, 3-4 parts water-reducing agent, 2-4 parts penetrating crystalline waterproofing agent, 7-18 parts expansion agent, and 100-200 parts water. The penetrating crystalline waterproofing agent comprises a precipitating agent, a complex, and a calcium ion compensator mixed in a weight ratio of 3:2:

5. The penetrating crystalline waterproofing agent also includes a surfactant, which accounts for 0.1%-1% by weight in the penetrating crystalline waterproofing agent; The precipitation reagent is a mixture of sodium silicate, sodium carbonate and potassium phosphate, in a weight ratio of 6-8:3-4:1-2. The complex is a mixture of potassium sodium tartrate and sodium gluconate, wherein the weight ratio of potassium sodium tartrate to sodium gluconate does not exceed 35:

1. The calcium ion compensator is a mixture of calcium acetate and calcium hydroxide, wherein the weight ratio of calcium acetate to calcium hydroxide is 3:

7. The surfactant is hexadecyltrimethylammonium bromide; The iron tailings sand and river sand are blended to a fineness modulus of 2.2-2.6, and the porosity of the blended sand is less than 40%.

2. The low-shrinkage, high-strength, self-healing concrete according to claim 1, characterized in that, The expanding agent comprises calcium oxide, sulfur trioxide, and silicon dioxide, wherein the content of calcium oxide is 50%-70%, the content of sulfur trioxide is 10%-20%, and the content of silicon dioxide is 3%-10%.

3. The low-shrinkage, high-strength, self-healing concrete according to claim 2, characterized in that, The expanding agent is a solid powder with a density of 2.85 g / cm³ and a specific surface area of ​​336 m² / kg.

4. The low-shrinkage, high-strength, self-healing concrete according to claim 1, characterized in that, The nano-silica has a purity greater than 98%, a particle size of 6-30 nm, a specific surface area of ​​300 m², and a refractive index of not less than 1.45%.

5. The low-shrinkage, high-strength, self-healing concrete according to claim 1, characterized in that, The river sand has a fineness modulus of 2.6, a bulk density of 1410 kg / m³, an apparent density of 2763 kg / m³, a stone powder content of 1.9%, and a water absorption rate of 1.3%.

6. The low-shrinkage, high-strength, self-healing concrete according to claim 1, characterized in that, The iron tailings sand has a silica content greater than 75%, a fineness modulus of 2.5, a bulk density of 1398 kg / m³, an apparent density of 2650 kg / m³, a stone powder content of 1.8%, and a water absorption rate of 4.6%.

7. The low-shrinkage, high-strength, self-healing concrete according to claim 1, characterized in that, The coarse aggregate is one or a combination of two of the following: basalt, granite, gneiss, and andesite crushed stone with a particle size of 5-20 mm and a crushing index of 5.5% and a bulk density of 1410 kg / m³.

8. The low-shrinkage, high-strength, self-healing concrete according to claim 1, characterized in that, The fly ash is secondary fly ash, with a sulfur trioxide content of 0.45%, a specific surface area of ​​570 m² / kg, a water requirement ratio of 92%, and a loss on ignition of 4.2%.

9. The low-shrinkage, high-strength, self-healing concrete according to claim 1, characterized in that, The cement is P.Ⅱ52.5 silicate cement, and the total mass percentage of silica, calcium oxide and alumina in the cement is not less than 80%. The specific surface area of ​​the cement is 385 m² / g, the apparent density is 3010 kg / m³, and the 28-day strength is ≥55 MPa.

10. The low-shrinkage, high-strength, self-healing concrete according to claim 1, characterized in that, The water-reducing agent is a composite polycarboxylate high-efficiency water-reducing agent with a molecular topological structure, a water reduction rate of >25%, and a solid content of 20%±2%.

11. A method for preparing low-shrinkage, high-strength, self-healing concrete as described in any one of claims 1-10, characterized in that, The method involves measuring each raw material according to a weight ratio, and includes the following steps: Step 1: Mix the penetrating crystalline waterproofing agent and water thoroughly to obtain solution A; Step 2: Mix nano-silica and water-reducing agent and disperse by ultrasonication to obtain suspension B; Step 3: Mix the iron tailings sand and river sand to a fineness modulus of 2.2-2.6, and the porosity of the mixed material is less than 40%; then mix the mixed iron tailings sand, river sand, coarse aggregate, cement and fly ash evenly to obtain dry mix C. Step 4: Add solution A to dry mixture C and stir until homogeneous to obtain slurry D; Step 5: Add suspension B to slurry D and stir evenly to obtain slurry E; Step 6: Add the expansion agent to slurry E and stir evenly to obtain low-shrinkage, high-strength, self-healing concrete.

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