Rapid repairing material for bridge expansion joint anchoring area and preparation method of rapid repairing material

Abstract

The invention discloses a rapid repairing material for an anchoring area of a bridge expansion joint and a preparation method of the rapid repairing material. The rapid repairing material is prepared from the following raw materials in parts by weight: a magnesium oxide cement binding material, an additive, fine aggregate, coarse aggregate, a functional aid and water, wherein the functional auxiliary agent comprises ammonium dihydrogen phosphate, polyethylene glycol and calcium stearate, the surface of ammonium dihydrogen phosphate particles is uniformly coated with the polyethylene glycol through a spray drying method, and then the surface of the polyethylene glycol-ammonium dihydrogen phosphate particles is coated with calcium stearate powder in a mechanical mixing mode, so that the functional auxiliary agent is obtained; the repairing material is prepared by uniformly mixing the coarse aggregate, the magnesium oxide cement binding material, the additive and the fine aggregate, adding the functional additive, uniformly mixing, adding water, and uniformly stirring. The rapid repairing material is beneficial to construction, has high early strength, can be opened in a short time, and ensures that the later strength is not reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of pavement repair materials, and particularly relates to a bridge expansion joint anchorage zone rapid repair material and a preparation method thereof. BACKGROUND

[0002] The bridge expansion joint anchorage zone concrete is prone to damage phenomena such as cracking, net cracking, peeling and the like due to long-term exposure to air, a harsh use environment and repeated impact of loads, and peeling of the concrete from the main beam structure and the bridge deck pavement layer. Therefore, the bridge expansion joint anchorage zone concrete always needs to be repaired, but repeated damage often occurs after repair.

[0003] At present, common repair technologies for the bridge expansion joint anchorage zone mainly include ordinary concrete repair, fast-hardening cement concrete repair, modified asphalt mixture repair and epoxy resin concrete repair. The ordinary concrete repair has a long curing period, which causes slow repair of the bridge expansion joint, prolongs the road closure period, affects vehicle traffic, and has a negative impact on highway operation. Although the fast-hardening cement concrete has excellent early strength, it has deficiencies in late strength, durability, elasticity and impact resistance and the like, and is prone to secondary cracking and damage within a short period after repair.

[0004] In the prior art, a magnesium phosphate cement-based material is used for repair; the magnesium phosphate cement has excellent bonding performance with the base material, can effectively repair cracks and damaged parts, and has high compressive and flexural strength within a short time; due to the fast reaction speed of the magnesium phosphate cement material, the material is often hardened before construction after mixing of raw materials, and thus cannot be constructed; therefore, borax is added to the magnesium phosphate cement material to delay the setting time.

[0005] However, in the prior art, the borax affects the early strength of the magnesium phosphate cement material, increases the viscosity of the slurry, affects the fluidity, and even cracks and defects may occur in the magnesium phosphate cement crystals, which may affect the long-term durability; therefore, the borax is not a good choice for delaying the setting time of the magnesium phosphate cement material.

[0006] Therefore, there is an urgent need for a new repair material which can delay the setting time of the magnesium phosphate cement material without affecting the early and late strength of the magnesium phosphate cement material. SUMMARY

[0007] The present application aims to provide a bridge expansion joint anchorage zone rapid repair material which has high early strength to shorten the curing time, has a certain fluidity, delays the setting time for convenient construction, and ensures that the late strength does not decrease.

[0008] Technical solution: The bridge expansion joint anchorage zone rapid repair material provided by the application comprises the following raw materials in parts by weight: magnesia cementitious material 45-50 parts, additive 0.15-0.30 parts, fine aggregate 10-14 parts, coarse aggregate 33-38 parts, functional additive 2-4 parts and water 3-5 parts; wherein the functional additive comprises ammonium dihydrogen phosphate, polyethylene glycol and calcium stearate in a mass ratio of 1:(0.03-0.05):(0.05-0.08), and the structure of the functional additive is that the ammonium dihydrogen phosphate particles, the polyethylene glycol slow-release layer and the calcium stearate water-repellent layer are sequentially arranged from inside to outside.

[0009] The application adopts the magnesia cementitious material, and on the basis of improving the early strength of the magnesium phosphate cement, when the magnesium phosphate cement is prepared by using the magnesia and ammonium dihydrogen phosphate, a layered coating structure functional additive composed of ammonium dihydrogen phosphate, polyethylene glycol and calcium stearate is introduced, that is, the polyethylene glycol is first coated on the ammonium dihydrogen phosphate, and then the calcium stearate is coated on the polyethylene glycol, the surface of the polyethylene glycol is hydrophobically modified by the calcium stearate, and the polyethylene glycol and the ammonium dihydrogen phosphate are prevented from being dissolved first in the mixing process of the repair material in the early hydration stage; the reaction between the ammonium dihydrogen phosphate and the magnesia is temporarily isolated in the early hydration stage by the coating of the polyethylene glycol, the setting time of the repair material is delayed, the fluidity is improved, and sufficient time is provided for construction. With the continuous heat release in the cement hydration process in the magnesia cementitious material system, the temperature of the entire repair material system is continuously increased, and when the hydration heat temperature is increased to a certain degree, the polyethylene glycol is melted, the ammonium dihydrogen phosphate coated by the polyethylene glycol is released, and then reacts with the magnesia to form the magnesium phosphate cement, thereby improving the early strength of the repair material. In addition, the ammonium dihydrogen phosphate and the magnesia release a large amount of heat, accelerate the setting and hardening of the low-alkalinity cement gel material, and make the early strength of the repair material increase faster and more quickly.

[0010] Further, the magnesia cementitious material used in the repair material of the application comprises the following raw materials in parts by weight: cement 65-70 parts, silica powder 3-5 parts, magnesia 19-22 parts and fly ash 5-8 parts.

[0011] Further, the additive used in the repair material of the application comprises a polycarboxylate superplasticizer and tartaric acid in a mass ratio of 1:(0.5-1.0).

[0012] Further, the fine aggregate used in the repair material of the application is quartz sand with a particle size of 0.15-5 mm.

[0013] Further, the coarse aggregate used in the repair material of the application is shale ceramsite or coal gangue ceramsite with a particle size of 3-8 mm and an apparent density of 800-1000 kg / m 3 , the cylinder compressive strength is ≥4.5 MPa, and the coarse aggregate is in a saturated surface-dry state.

[0014] Further, the cement used in the patching material of the present application is 42.5 grade low alkalinity sulphoaluminate cement; the magnesium oxide is heavy-burned magnesium oxide, and the fly ash is first-grade ash, and the specific surface area of the magnesium oxide and the fly ash is greater than 300 m 2 / kg; the SiO2 content of the silica powder is greater than or equal to 96%, and the specific surface area thereof is greater than 20000 m 2 / kg.

[0015] Further, the molecular weight of the polyethylene glycol used in the patching material of the present application is 3000-6000.

[0016] Further, the functional additive used in the patching material of the present application is prepared by the following steps: uniformly coating polyethylene glycol on the surface of ammonium dihydrogen phosphate particles by a spray drying method, and then coating calcium stearate powder on the surface of the polyethylene glycol-ammonium dihydrogen phosphate particles by a mechanical mixing method to obtain the functional additive.

[0017] The preparation method of the bridge expansion joint anchoring area rapid patching material of the present application comprises the following steps:

[0018] (1) Preparing coarse aggregate: soaking the coarse aggregate in water until the saturated surface-dry state is reached;

[0019] (2) Preparing rapid patching material: uniformly mixing the magnesium oxide cementitious material, the additive, the fine aggregate and the coarse aggregate prepared in step (1), then adding the functional additive, and uniformly mixing and then adding water and stirring.

[0020] Beneficial effects: Compared with the prior art, the significant advantages of the present application are: the rapid patching material not only has high early strength, and the 2h and 1d compressive strengths thereof are not less than 30MPa and 45MPa respectively, which can effectively shorten the curing opening time; at the same time, the setting time of the patching material can be controlled in the range of 30-50min, which provides a favorable operation time range for construction; and the late strength thereof can be ensured not to be reduced, and the late strength is high, and the 7d and 28d compressive strengths thereof are not less than 50MPa and 60MPa respectively. DETAILED DESCRIPTION

[0021] The technical solutions of the present application will be further described in detail below in combination with examples.

[0022] In the raw materials used in the present application, the cement is 42.5 grade low alkalinity sulphoaluminate cement; the SiO2 content of the silica powder is 98%, and the specific surface area thereof is 30000 m 2 / kg; the magnesium oxide is heavy-burned magnesium oxide, and the fly ash is first-grade ash, and the specific surface area of the heavy-burned magnesium oxide and the fly ash reaches 400 m 2 / kg; the particle size of the coarse aggregate is 3mm, and the apparent density thereof is 900 kg / m 3The fine aggregate is quartz sand with a particle size of 5 mm; and the molecular weight of the polyethylene glycol is 3000.

[0023] The mass ratio of the ammonium dihydrogen phosphate, the polyethylene glycol and the calcium stearate in the functional additive is 1:(0.03-0.05):(0.05-0.08), and the specific mass ratio is shown in Table 2; and the specific preparation method comprises the following steps:

[0024] (1) Put the ammonium dihydrogen phosphate particles into a fluidized bed, start the air system of the fluidized bed, and make the ammonium dihydrogen phosphate particles in a uniform distribution state by controlling the air flow to be 30 m 3 / h;

[0025] (2) Dissolve the polyethylene glycol in ethanol to form a polyethylene glycol solution with a concentration of 15%; start the spraying system, and spray the polyethylene glycol solution on the surface of the ammonium dihydrogen phosphate particles in the fluidized state at a speed of 10 mL / min;

[0026] (3) Control the temperature of the fluidized bed to be 60℃ to make the polyethylene glycol solution quickly dry on the surface of the ammonium dihydrogen phosphate particles to form a uniform coating film;

[0027] (4) After the spraying is completed, continue to dry for 30 minutes to remove the residual ethanol solvent to obtain the ammonium dihydrogen phosphate coated with polyethylene glycol;

[0028] (5) Put the ammonium dihydrogen phosphate coated with polyethylene glycol into the calcium stearate powder, and ultrasonically mix for 0.5 h to make the calcium stearate wrapped on the surface of the polyethylene glycol to obtain the functional additive.

[0029] Example 1

[0030] In this example, the raw materials and components in the raw materials are weighed according to Table 1 and Table 2, and the main raw materials in Table 1 are used to determine the sub-raw materials; and the repair material is prepared according to the following steps:

[0031] (1) Prepare the coarse aggregate: the coarse aggregate is selected as shale ceramsite, and is soaked in water for 24 h to reach a saturated surface dry state and then taken out;

[0032] (2) Prepare the rapid repair material: first, mix the components of the magnesium oxide cementitious material and the components of the admixture evenly; then, mix the prepared magnesium oxide cementitious material, the admixture, the fine aggregate and the coarse aggregate prepared in step (1) evenly, and finally add the prepared functional additive, mix evenly, and then add water and stir evenly to obtain the bridge expansion joint anchorage zone rapid repair material.

[0033] Table 1

[0034]

[0035] Table 2 (the weight ratio of each component of raw materials in the table)

[0036]

[0037]

[0038] Example 2

[0039] The rapid repair material in this example is prepared according to the weight parts of the raw materials and each component in the raw materials in Table 1 and Table 2, and the repair material is prepared according to the following steps:

[0040] (1) Preparation of coarse aggregate: The coarse aggregate selected is shale ceramsite, which is soaked in water for 24 h, and taken out after reaching the saturated surface dry state;

[0041] (2) Preparation of rapid repair material: First, mix the components of the magnesium oxide cementitious material uniformly, and mix the components of the admixture uniformly; then mix the prepared magnesium oxide cementitious material, admixture, fine aggregate, and the coarse aggregate prepared in step (1) uniformly, then add the prepared functional additive, mix uniformly, and then add water and stir uniformly; the bridge expansion joint anchorage zone rapid repair material is obtained.

[0042] Example 3

[0043] The rapid repair material in this example is prepared according to the weight parts of the raw materials and each component in the raw materials in Table 1 and Table 2; and the repair material is prepared according to the following steps:

[0044] (1) Preparation of coarse aggregate: The coarse aggregate selected is coal gangue ceramsite, which is soaked in water for 24 h, and taken out after reaching the saturated surface dry state;

[0045] (2) Preparation of rapid repair material: First, mix the components of the magnesium oxide cementitious material uniformly, and mix the components of the admixture uniformly; then mix the prepared magnesium oxide cementitious material, admixture, fine aggregate, and the coarse aggregate prepared in step (1) uniformly, then add the prepared functional additive, mix uniformly, and then add water and stir uniformly; the bridge expansion joint anchorage zone rapid repair material is obtained.

[0046] Comparative Example 1

[0047] The rapid repair material in this example is prepared according to the weight parts of the raw materials and each component in the raw materials in Table 1 and Table 2; it can be seen that the components of Comparative Example 1 and Example 1 are basically the same, the difference is that the functional additive is ammonium dihydrogen phosphate and calcium stearate; the repair material is prepared according to the following steps:

[0048] (1) Preparation of functional additives: ammonium dihydrogen phosphate particles were mixed with calcium stearate powder, and ultrasonic mixing was performed for 0.5 h to allow calcium stearate to coat the surface of ammonium dihydrogen phosphate;

[0049] (2) Preparation of coarse aggregate: shale ceramsite was selected as the coarse aggregate, which was soaked in water for 24 h, and then taken out when it reached the saturated surface dry state;

[0050] (3) Preparation of rapid repair material: first, the components of magnesium oxide cementitious material were mixed uniformly, and the components of admixture were mixed uniformly; then the prepared magnesium oxide cementitious material, admixture, fine aggregate, and coarse aggregate prepared in step (2) were mixed uniformly, and then the functional additive prepared in step (1) was added, mixed uniformly, and then water was added and stirred uniformly; the bridge expansion joint anchorage zone rapid repair material was obtained.

[0051] Comparative Example 2

[0052] In this example, the raw materials and components in the raw materials were weighed according to Tables 1 and 2; it can be seen that the components of Comparative Example 1 and Example 1 are basically the same, the difference is that the functional additive is only ammonium dihydrogen phosphate; the repair material was prepared according to the following steps:

[0053] (1) Preparation of coarse aggregate: shale ceramsite was selected as the coarse aggregate, which was soaked in water for 24 h, and then taken out when it reached the saturated surface dry state;

[0054] (2) Preparation of rapid repair material: the components of magnesium oxide cementitious material were mixed uniformly, and the components of admixture were mixed uniformly; then the magnesium oxide cementitious material, fine aggregate, admixture, and coarse aggregate prepared in step (1) were mixed uniformly, and then the functional additive ammonium dihydrogen phosphate was added, mixed uniformly, and then water was added and stirred uniformly; the bridge expansion joint anchorage zone rapid repair material was obtained.

[0055] Performance test

[0056] I. Setting time test

[0057] The bridge expansion joint anchorage zone rapid repair materials prepared in Examples 1-3 and Comparative Examples 1-2 were determined for setting time at 20℃ according to JTG 3420-2020, and the results are shown in Table 3.

[0058] Table 3

[0059] Examples Initial set time / min Final set time / min Example 1 32 39 Example 2 43 49 Example 3 44 47 Comparative Example 1 12 15 Comparative Example 2 6 10

[0060] II. Compressive strength test

[0061] The bridge expansion joint anchorage zone rapid repairing material prepared from examples 1-3 and comparative examples 1-2 is poured into a mold with a size of 150mm*150mm*150mm, 12 pieces per group, vibration densification on a vibration table, scraping, and placed in a curing box with a temperature of 20℃ and a relative humidity of 90% for curing, and the 2h compressive strength is tested after 2h, and the rest is placed in the curing box for curing until 1d, 7d and 28d ages, and the compressive strength is measured, and the results are shown in Table 4.

[0062] Table 4

[0063]

[0064] From the setting time in Table 3 and the compressive strength at 1d, 7d and 28d ages in Table 4, it can be seen that the initial setting time in examples 1-3 is delayed to more than 30min, enough operation time is reserved for the staff, and the compressive strength after 1d is as high as 45MPa, and the compressive strength at 28d is as high as 60MPa, completely meeting the strength requirements of early and late cement repairing materials.

[0065] In comparative example 2, ammonium dihydrogen phosphate and magnesium oxide in the retarder-free component will react quickly, and can completely solidify in about ten minutes, and this quick setting time leads to the failure of construction operation. In comparative example 1, ammonium dihydrogen phosphate is coated with a hydrophobic agent, and the time is only prolonged by five or six minutes compared with comparative example 2, and it can be seen that directly coating ammonium dihydrogen phosphate with a hydrophobic agent cannot effectively delay the release time of ammonium dihydrogen phosphate.

[0066] In the bridge expansion joint anchorage zone rapid repairing material of the application, the mass ratio of ammonium dihydrogen phosphate, polyethylene glycol and calcium stearate can be 1:(0.03-0.05):(0.05-0.08); the mass ratio of polycarboxylate superplasticizer and tartaric acid can be 1:(0.5-1.0); the particle size of fine aggregate can be 0.15-5mm; the particle size of coarse aggregate can be 3-8mm, and the apparent density can be 800-1000kg / m 3 , the cylinder compressive strength is ≥4.5MPa; the specific surface area of magnesium oxide and fly ash is greater than 300m 2 / kg; the SiO2 content in silica powder is ≥96%, and the specific surface area is greater than 20000m 2 / kg; the molecular weight of polyethylene glycol can be 3000-6000; using the preparation process and the defined parameter range of the application, the technical effects claimed by the application can be achieved, and therefore, it is not necessary to separately list the evidence.

Claims

1. A rapid repair material for the anchorage area of ​​a bridge expansion joint, characterized in that: The invention comprises the following raw materials in parts by weight: 45-50 parts of magnesium oxide cement binder, 0.15-0.30 parts of admixture, 10-14 parts of fine aggregate, 33-38 parts of coarse aggregate, 2-4 parts of functional additives and 3-5 parts of water; wherein the functional additives comprise ammonium dihydrogen phosphate, polyethylene glycol and calcium stearate in a mass ratio of 1:(0.03-0.05):(0.05-0.08), and the structure of the functional additives is, from the inside out, ammonium dihydrogen phosphate particles, a polyethylene glycol sustained-release layer and a calcium stearate hydrophobic layer.

2. The rapid repair material for the anchorage area of ​​a bridge expansion joint according to claim 1 is characterized in that: The magnesium oxide cement gelling material comprises the following raw materials in parts by weight: 65-70 parts of cement, 3-5 parts of silica powder, 19-22 parts of magnesium oxide and 5-8 parts of fly ash.

3. The rapid repair material for the anchorage area of ​​a bridge expansion joint according to claim 1 is characterized in that: The admixture includes a polycarboxylate water reducer and tartaric acid in a mass ratio of 1:(0.5-1.0).

4. The rapid repair material for the anchorage area of ​​a bridge expansion joint according to claim 1, characterized in that: The fine aggregate is quartz sand with a particle size of 0.15-5 mm.

5. The rapid repair material for the anchorage area of ​​a bridge expansion joint according to claim 1 is characterized in that: The coarse aggregate is shale ceramsite or coal gangue ceramsite with a particle size of 3-8 mm and an apparent density of 800-1000 kg / m 3 , cylinder compressive strength ≥4.5MPa; and the coarse aggregate is in a saturated surface dry state.

6. The rapid repair material for the anchorage area of ​​a bridge expansion joint according to claim 2, characterized in that: The cement is 42.5 grade low alkalinity sulphoaluminate cement; the magnesium oxide is dead-burned magnesium oxide; the fly ash is first-grade ash; the specific surface area of ​​the magnesium oxide and the fly ash is greater than 300m 2 / kg; the SiO2 content in the silicon micropowder is ≥96%, and its specific surface area is greater than 20,000m 2 / kg.

7. The rapid repair material for the anchorage area of ​​a bridge expansion joint according to claim 1, characterized in that: The molecular weight of the polyethylene glycol is 3000-6000.

8. The rapid repair material for anchorage areas of bridge expansion joints according to claim 1, characterized in that: The functional additive is prepared by the following steps: polyethylene glycol is evenly coated on the surface of ammonium dihydrogen phosphate particles by spray drying, and calcium stearate powder is then coated on the surface of the polyethylene glycol-dihydrogen phosphate particles by mechanical mixing to obtain the functional additive.

9. A method for preparing a rapid repair material for an anchorage area of ​​a bridge expansion joint according to any one of claims 1 to 8, characterized in that: The following steps are involved: (1) Preparation of coarse aggregate: Soak the coarse aggregate in water until it reaches a saturated surface dry state; (2) Preparing a quick repair material: Mix the magnesium oxide cement binder, admixture, fine aggregate and the coarse aggregate prepared in step (1) evenly, then add the functional additive, mix evenly, and then add water and stir evenly.

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