Self-healing UHPC (Ultra High Performance Concrete) material for bridge deck pavement and preparation method of self-healing UHPC material

Abstract

The invention discloses a self-healing UHPC material for bridge deck pavement and a preparation method thereof, and belongs to the technical field of concrete preparation, the material comprises 80-120 parts of cement, 20-35 parts of fine sand, 15-25 parts of a fine admixture, 10-20 parts of an additive, 13-22 parts of microfibers, 15-25 parts of a self-healing capsule, and 8-15 parts of an active proliferation agent; the cement is high-strength and low-porosity cement; the fine admixture is composed of silicon powder, slag powder and fly ash in a mass ratio of 1: 1: 1; the additive is an efficient water reducing agent; the microfibers are at least one of steel fibers, carbon fibers and glass fibers; the self-healing capsule is composed of urea resin, a capsule core material, a diluent, an imidazole curing agent and an auxiliary material. The UHPC material disclosed by the invention has high strength and high toughness, can bear larger load and deformation, and is several times of that of common concrete; the UHPC material also has high compactness and high durability, can resist various erosion and aging factors, has durability, and effectively prolongs the service life.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete preparation, and in particular relates to a self-healing UHPC material for bridge deck pavement and a preparation method thereof. Background Art

[0002] Ultra-high-performance concrete (UHPC), previously known as reactive powder concrete (RPC) in its early stages of development, is a cement-based composite material produced by optimizing particle grading, incorporating steel fibers, and employing an ultra-low water-cement ratio (typically <0.20). After 30 years of development, UHPC has transitioned from laboratory research to practical engineering applications. Its compressive strength can reach 120-200 MPa, and its elastic modulus exceeds 45 GPa, demonstrating excellent mechanical properties and durability. Particularly in the field of bridge deck paving, its high impermeability and wear resistance make it a promising solution to the rutting problems of conventional asphalt concrete and the cracking of cement concrete.

[0003] However, engineering practice has found that UHPC's inherently low water-to-binder ratio results in a high autogenous shrinkage value, approximately 3-5 times that of ordinary concrete, and is prone to microcracks during the initial curing period. Furthermore, during construction, it was discovered that its high fluidity and low cohesion not only require strict construction conditions but are also prone to defects such as hollowing and cracking, and are prone to grout leakage and misalignment at formwork joints.

[0004] In addition, when UHPC is used for bridge deck pavement, due to the alternating stress caused by dynamic vehicle loading and temperature cycles, calcium dissolution caused by deicing salt erosion, and degradation of the steel fiber and matrix interface caused by ultraviolet radiation, microcracks will generally appear in the UHPC pavement layer of the bridge deck after a few years of service, which will in turn cause chain damage such as steel bar corrosion and interlayer delamination.

[0005] Existing repair technologies, such as epoxy resin grouting, have difficulty penetrating microcracks and carry the risk of secondary cracking due to differences in thermal expansion coefficients. Furthermore, the unique traffic demands of bridge decks often present new challenges for traditional repair methods, such as limited road closures and insufficient anti-slip properties of the repair layer. While some studies have attempted to embed microcapsules within UHPC, the microcapsules have poor compatibility with the UHPC matrix and are prone to premature rupture under high-frequency vibrations of the bridge deck. Summary of the Invention

[0006] In view of this, the object of the present invention is to provide a self-healing UHPC material for bridge deck pavement and a preparation method thereof, so as to solve the problem that the current UHPC material is prone to cracking and cannot heal.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] The present invention provides a self-healing UHPC material for bridge deck pavement. The material comprises, by weight, 80-120 parts of cement, 20-35 parts of fine sand, 15-25 parts of fine admixture, 10-20 parts of additives, 13-22 parts of microfibers, 15-25 parts of self-healing capsules, and 8-15 parts of active proliferation agent.

[0009] The cement is high-strength, low-porosity cement; the fine admixture is composed of silicon powder, slag powder, and fly ash in a mass ratio of 1:1:1; the additive is a high-efficiency water reducer; the microfiber is at least one of steel fiber, carbon fiber, and glass fiber; the self-healing capsule is composed of urea-formaldehyde resin, capsule core material, diluent, imidazole curing agent, and auxiliary materials.

[0010] Furthermore, the urea-formaldehyde resin is synthesized from urea and formaldehyde; the capsule core material is epoxy resin glue, specifically E-51 epoxy resin; the diluent is n-butyl glycidyl ether; the curing agent is an imidazole curing agent, specifically MC120D; and the auxiliary materials are acidifier, catalyst, and surfactant.

[0011] Furthermore, the cement is at least one of ordinary Portland cement and slag Portland cement; the high-efficiency water reducer is an aminosulfonate water reducer; and the active proliferation agent is an active silicon ion proliferation agent.

[0012] Furthermore, the acidifier is nitric acid, the catalyst is a silicate catalyst, and the surfactant is lignin sulfonate.

[0013] Furthermore, a method for preparing a self-healing UHPC material for bridge deck pavement comprises the following steps:

[0014] S1. Add cement and fine sand into water and pre-mix, then add active growth agent and continue mixing;

[0015] S2, then add fine admixture, microfiber and additives and stir into a paste;

[0016] S3, adding the self-healing capsules and stirring evenly to form a concrete slurry;

[0017] S4, pouring the concrete slurry into the mold, vibrating and curing;

[0018] S5. Then cure under corresponding temperature and humidity conditions to ensure that the concrete is fully hydrated and achieves optimal performance, thus obtaining self-healing UHPC material.

[0019] Furthermore, in step S1, the mixing time of cement and fine sand is 20-30 minutes, the stirring rate is 100-120 rpm / min, and the stirring time after the active proliferation agent is added is 15-20 minutes.

[0020] Furthermore, in the step S2, after the fine admixture, microfiber and additive are added, the stirring time is 25-35 minutes; in the step S3, after the self-healing capsule is added, the stirring time is 15-20 minutes.

[0021] Furthermore, in step S5, the curing temperature of the concrete is room temperature, water is added multiple times to moisten the concrete surface, and the relative humidity should be above 95%.

[0022] Furthermore, in step S2, the self-healing capsules are prepared by the following steps:

[0023] P1, urea and formaldehyde were mixed in a molar ratio of 1.5:1.0, and reacted at 70° C. for 1 hour to synthesize a urea-formaldehyde resin prepolymer;

[0024] P2, E-51 cyclic resin, n-butyl glycidyl ether and MC120D curing agent were mixed in a mass ratio of 1:1:1 to form an epoxy resin glue;

[0025] P3. Use in-situ polymerization method to use epoxy resin glue as core material and urea-formaldehyde resin prepolymer as wall material, and synthesize micron-sized self-healing capsules under corresponding conditions.

[0026] Furthermore, in step P3, the corresponding temperature is first 50° C. for acidification, and then increased to 60° C. to enhance the solidification of the capsule wall.

[0027] The beneficial effects of the present invention are:

[0028] 1. The UHPC material of the present invention has high strength and toughness, capable of withstanding greater loads and deformations. Its strength can reach 130 MPa, several times that of ordinary concrete. Furthermore, UHPC material has high density and durability, making it resistant to various corrosion and aging factors. It also has long durability, effectively extending its service life. Furthermore, UHPC material has low carbon emissions and can be effectively recycled and reused, achieving environmentally friendly results.

[0029] 2. The UHPC material of the present invention has high strength and high toughness. Under the same paving environment, its usage is reduced by 50-75% compared with ordinary concrete, saving material and transportation costs and energy consumption. At the same time, the self-healing function also reduces the cost and time of maintenance and repair.

[0030] 3. In the present invention, when concrete cracks, the self-healing capsules will rupture and release healing substances. The healing substances can react with cement hydration products to generate new gelling substances, filling the cracks and restoring the strength and density of the concrete. The release of self-healing gel is a continuous process, which can continuously repair tiny cracks in the concrete.

[0031] 4. In the present invention, the acidifier in the growth agent improves the physical and chemical properties of concrete and enhances its durability. The catalyst accelerates the reaction, increasing the early strength and durability of concrete by accelerating the hydration reaction of cement. The surfactant's dispersing effect: The surfactant disperses cement particles and reduces agglomeration, thereby improving the workability and fluidity of concrete and increasing its strength and durability. The addition of the growth agent of the present invention forms a continuous network of crystals within the concrete. When new cracks appear, these crystals will "resurrect" and undergo a growth reaction to seal the new cracks.

[0032] 5. In the present invention, the addition of fine admixtures and microfibers can improve the toughness and crack resistance of concrete, making the concrete less likely to crack when subjected to external forces; at the same time, the high-efficiency water reducer can improve the fluidity and uniformity of concrete, which helps to evenly distribute the self-healing capsules in the concrete.

[0033] 6. The UHPC material of the present invention has broad application prospects in engineering fields such as bridges, buildings, and tunnels due to its high strength, high durability, and self-healing ability.

[0034] Other advantages, objectives and features of the present invention will be described in the following description and will be apparent to those skilled in the art to some extent, or those skilled in the art can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to make the purpose, technical solutions and beneficial effects of the invention clearer, the present invention is described with the following drawings:

[0036] Figure 1 This is a process flow chart for the preparation of the present invention. DETAILED DESCRIPTION

[0037] like Figure 1 As shown, the present invention provides a method for preparing a self-healing UHPC material for bridge deck pavement.

[0038] Example 1

[0039] S1. Add 80 parts of cement and 20 parts of fine sand into water and stir at 100 rpm / min for 25 minutes. Then add 8 parts of active growth agent and continue stirring for 18 minutes.

[0040] S2, then add 15 parts of fine admixture and 13 parts of microfiber and stir for 15 minutes, and add 10 parts of high-efficiency water reducer under stirring conditions and stir until it becomes a paste;

[0041] S3, adding 15 parts of self-healing capsules and continuing stirring for 18 minutes to obtain concrete slurry;

[0042] S4. Pour the concrete slurry into the mold, vibrate and cure until the concrete reaches the designed strength;

[0043] S5. Then, at room temperature, water is poured onto the surface to maintain the relative humidity above 95%, ensuring that the concrete is fully hydrated and achieves optimal performance, thus obtaining a self-healing UHPC material.

[0044] In the present invention, cement, as the main cementitious material, can provide the basic strength of concrete; fine sand can fill the gaps between cement particles to form a denser concrete structure; fine admixtures can improve the fluidity of cement slurry and enhance the strength, impermeability and durability of UHPC materials; microfibers significantly improve the toughness and crack resistance of UHPC materials and help achieve self-healing function; high-efficiency water reducers can reduce the viscosity of cement slurry and improve fluidity and uniformity.

[0045] Example 2

[0046] S1. Add 120 parts of cement and 35 parts of fine sand into water and stir at 100 rpm / min for 25 minutes. Then add 15 parts of active growth agent and continue stirring for 18 minutes.

[0047] S2, then add 25 parts of fine admixture and 22 parts of microfiber and stir for 15 minutes, and add 10 parts of high-efficiency water reducer under stirring conditions and stir until it becomes a paste;

[0048] S3, adding 25 parts of self-healing capsules and continuing stirring for 18 minutes to obtain concrete slurry;

[0049] S4. Pour the concrete slurry into the mold, vibrate and cure until the concrete reaches the designed strength;

[0050] S5. Then, at room temperature, water is poured onto the surface to maintain the relative humidity above 95%, ensuring that the concrete is fully hydrated and achieves optimal performance, thus obtaining a self-healing UHPC material.

[0051] The difference between Example 2 and Example 1 is that the number of parts of each raw material component is different, but both are within the scope of protection of the present invention.

[0052] Example 3

[0053] S1. Add 100 parts of cement and 28 parts of fine sand into water and stir at 100 rpm / min for 25 minutes. Then add 12 parts of active growth agent and continue stirring for 18 minutes.

[0054] S2, then add 20 parts of fine admixture and 16 parts of microfiber and stir for 15 minutes, and add 10 parts of high-efficiency water reducer under stirring conditions and stir until it becomes a paste;

[0055] S3, adding 20 parts of self-healing capsules and continuing stirring for 18 minutes to obtain concrete slurry;

[0056] S4. Pour the concrete slurry into the mold, vibrate and cure until the concrete reaches the designed strength;

[0057] S5. Then, at room temperature, water is poured onto the surface to maintain the relative humidity above 95%, ensuring that the concrete is fully hydrated and achieves optimal performance, thus obtaining a self-healing UHPC material.

[0058] The difference between Example 3 and Example 1 is that the number of parts of each raw material component is different, but both are within the scope of protection of the present invention.

[0059] In order to verify the superiority of the raw materials, methods and ratios of the present invention, comparative examples 1 to 4 are set here.

[0060] Comparative Example 1

[0061] S1. Add 80 parts of cement and 20 parts of fine sand into water and stir at 100 rpm / min for 25 minutes.

[0062] S2, then add 15 parts of fine admixture and 13 parts of microfiber and stir for 15 minutes, and add 10 parts of high-efficiency water reducer under stirring conditions, stir until it becomes a paste to obtain concrete slurry;

[0063] S3, pouring concrete slurry into the mold, vibrating and curing until the concrete reaches the designed strength;

[0064] S4. Then, at room temperature, water is poured onto the surface to maintain the relative humidity above 95%, ensuring that the concrete is fully hydrated and achieves optimal performance, thereby obtaining UHPC material.

[0065] The difference between Comparative Example 1 and Example 1 is that the self-healing capsules and active silicon ion multiplier are not included, and the UHPC material obtained has almost no healing function. After the construction is completed, cracks exist during use that have not healed.

[0066] Comparative Example 2

[0067] S1. Add 80 parts of cement and 20 parts of fine sand into water and stir at 100 rpm / min for 25 minutes. Then add 8 parts of active multiplication agent and continue stirring for 18 minutes. Then, add 10 parts of high-efficiency water reducer under stirring conditions and stir until it becomes a paste.

[0068] S2, adding 15 parts of self-healing capsules and continuing stirring for 18 minutes to obtain concrete slurry;

[0069] S3, pouring concrete slurry into the mold, vibrating and curing until the concrete reaches the designed strength;

[0070] S4. Then, at room temperature, water is poured onto the surface to maintain the relative humidity above 95%, ensuring that the concrete is fully hydrated and achieves optimal performance, thus obtaining a self-healing UHPC material.

[0071] The difference between Comparative Example 2 and Example 1 is that no fine admixture or microfiber is added, and the obtained UHPC material has insufficient rigidity and is prone to collapse during use. After collapse, the UHPC material cannot be effectively healed.

[0072] Comparative Example 3

[0073] S1. Add 140 parts of cement and 10 parts of fine sand into water and stir at 100 rpm / min for 25 minutes. Then add 20 parts of active growth agent and continue stirring for 18 minutes.

[0074] S2, then add 5 parts of fine admixture and 30 parts of microfiber and stir for 15 minutes, and add 5 parts of high-efficiency water reducer under stirring conditions and stir until it becomes a paste;

[0075] S3, adding 5 parts of self-healing capsules and continuing stirring for 18 minutes to obtain concrete slurry;

[0076] S4. Pour the concrete slurry into the mold, vibrate and cure until the concrete reaches the designed strength;

[0077] S5. Then, at room temperature, water is poured onto the surface to maintain the relative humidity above 95%, ensuring that the concrete is fully hydrated and achieves optimal performance, thereby obtaining UHPC material.

[0078] The difference between Comparative Example 3 and Example 1 is that the ratio of the raw materials is not within the scope of the present application, and the obtained UHPC material has poor self-healing performance and high brittleness, and cannot be effectively repaired and healed in time after cracking.

[0079] Comparative Example 4

[0080] S1. 80 parts of cement, 20 parts of fine sand, 15 parts of fine admixture, 10 parts of water reducer, 15 parts of self-healing capsules, and 8 parts of active silicon ion multiplier are stirred for 40 minutes to form a concrete paste;

[0081] S2. Pour the concrete slurry into the mold, vibrate and cure until the concrete reaches the designed strength;

[0082] S3. Then, at room temperature, water is poured onto the surface to maintain the relative humidity above 95%, ensuring that the concrete is fully hydrated and achieves optimal performance, thereby obtaining UHPC material.

[0083] The difference between Comparative Example 4 and Example 1 is that all the raw materials are directly added at once without giving each raw material sufficient reaction time, so the prepared UHPC material is not stirred evenly and has poor self-healing performance.

[0084] The self-healing UHPC materials prepared in Examples 1 to 3 and the UHPC materials prepared in Comparative Examples 1 to 4 were applied to the experimental road surface. After one natural month, their self-healing properties were tested. The results are shown in Table 1:

[0085]

[0086]

[0087] As can be seen from the table above, the self-healing UHPC materials of Examples 1-3, prepared using the raw materials, formulations, and methods of the present invention, exhibit high strength and toughness for engineering applications, as well as excellent self-healing performance and durability, making them effectively suitable for high-intensity environments. However, due to changes in formulations, raw materials, and methods, the resulting UHPC materials of Comparative Examples 1-4 exhibit various deficiencies and fail to effectively address the issues of the present invention. In summary, only materials produced using the raw materials, formulations, and methods of the present invention can be effectively applied and address the issues of the present invention.

[0088] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made in form and details without departing from the scope defined by the claims of the present invention.

Claims

1. A self-healing UHPC material for bridge deck pavement, characterized by: The material comprises, by weight, 80-120 parts of cement, 20-35 parts of fine sand, 15-25 parts of fine admixture, 10-20 parts of additives, 13-22 parts of microfibers, 15-25 parts of self-healing capsules, and 8-15 parts of active proliferation agent; The cement is high-strength, low-porosity cement; the fine admixture is composed of silicon powder, slag powder, and fly ash in a mass ratio of 1:1:1; the additive is a high-efficiency water reducer; the microfiber is composed of steel fiber, carbon fiber, and glass fiber in a mass ratio of 1:1:1; the self-healing capsule is composed of urea-formaldehyde resin, capsule core material, diluent, imidazole curing agent, and auxiliary materials.

2. The self-healing UHPC material for bridge deck pavement according to claim 1, characterized in that: The urea-formaldehyde resin is synthesized from urea and formaldehyde; the capsule core material is epoxy resin glue, specifically E-51 epoxy resin; the diluent is n-butyl glycidyl ether; the curing agent is an imidazole curing agent, specifically MC120D; and the auxiliary materials are an acidifier, a catalyst, and a surfactant.

3. The self-healing UHPC material for bridge deck pavement according to claim 1, characterized in that: The cement is at least one of ordinary Portland cement and slag Portland cement; the high-efficiency water reducer is an aminosulfonate water reducer; and the active proliferation agent is an active silicon ion proliferation agent.

4. The self-healing UHPC material for bridge deck pavement according to claim 2, characterized in that: The acidulant is nitric acid, the catalyst is a silicate catalyst, and the surfactant is lignin sulfonate.

5. A method for preparing a self-healing UHPC material for bridge deck pavement, using the UHPC material according to any one of claims 1 to 4, characterized in that: The following steps are included: S1. Add cement and fine sand into water and pre-mix, then add active growth agent and continue mixing; S2, then add fine admixture, microfiber and additives and stir into a paste; S3, adding the self-healing capsules and stirring evenly to form a concrete slurry; S4, pouring the concrete slurry into the mold, vibrating and curing; S5. Then cure under corresponding temperature and humidity conditions to ensure that the concrete is fully hydrated and achieves optimal performance, thus obtaining self-healing UHPC material.

6. The method for preparing a self-healing UHPC material for bridge deck pavement according to claim 5, characterized in that: In step S1, the cement and fine sand are stirred for 20-30 minutes at a stirring rate of 100-120 rpm / min, and the stirring time after the active proliferation agent is added is 15-20 minutes.

7. The method for preparing a self-healing UHPC material for bridge deck pavement according to claim 5, characterized in that: In the step S2, after the fine admixture, microfiber, and additive are added, the stirring time is 25-35 minutes; in the step S3, after the self-healing capsule is added, the stirring time is 15-20 minutes.

8. The method for preparing a self-healing UHPC material for bridge deck pavement according to claim 5, characterized in that: In step S5, the curing temperature of the concrete is room temperature, water is added multiple times to moisten the concrete surface, and the relative humidity should be above 95%.

9. The method for preparing a self-healing UHPC material for bridge deck pavement according to claim 5, characterized in that: In step S3, the self-healing capsules are prepared by the following steps: P1, urea and formaldehyde were mixed in a molar ratio of 1.5:1.0, and reacted at 70° C. for 1 hour to synthesize a urea-formaldehyde resin prepolymer; P2, E-51 cyclic resin, n-butyl glycidyl ether and MC120D curing agent were mixed in a mass ratio of 1:1:1 to form an epoxy resin glue; P3. Using the in-situ polymerization method, and adding acidifiers, catalysts, and surfactants, epoxy resin glue is used as the core material and urea-formaldehyde resin prepolymer is used as the wall material, and micron-sized self-healing capsules are synthesized under corresponding conditions.

10. The method for preparing a self-healing UHPC material for bridge deck pavement according to claim 9, characterized in that: In step P3, the corresponding temperature is first 50° C. for acidification, and then increased to 60° C. to enhance the solidification of the capsule wall.

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