Ultra-high performance concrete for cast-in-place wet joints with disturbance resistance and its preparation method

Abstract

This invention relates to the field of cement-based building materials technology, and in particular to an ultra-high performance concrete for cast-in-place wet joints with anti-disturbance properties and its preparation method. By using composite cement, composite admixtures, and high-quality fine aggregates, and preparing internal curing aggregates to achieve humidity control, a composite expansion agent is used to inhibit concrete shrinkage, a special water-reducing agent is used to adjust the concrete's workability, and an early-setting admixture is used to achieve high early strength, low shrinkage, and consistent setting time in the ultra-high performance concrete, thereby reducing the impact of external disturbances on road and bridge construction.

Description

Technical Field

[0001] This invention relates to the field of cement-based building materials technology, and in particular to an ultra-high performance concrete for cast-in-place wet joints resistant to disturbance and its preparation method. Background Technology

[0002] With the rapid development of logistics and transportation, road infrastructure such as highways and bridges are bearing increasingly heavy traffic loads, and the maintenance costs caused by defects are gradually increasing.

[0003] To meet the high load and long service life design requirements of roads and bridges, UHPC is gradually being widely used in construction. Modern roads and bridges have large spans and long lengths, and often adopt segmented construction or assembly, so the treatment of joints is particularly critical.

[0004] Ordinary joint concrete has high drying shrinkage and poor bonding effect, resulting in poor resistance to disturbance. There is an urgent need to develop new types of ultra-high performance concrete for wet joints with early strength, good volume stability and moderate setting time. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides an ultra-high performance concrete for cast-in-place wet joints that resists disturbance. By using composite cement, composite admixtures, and high-quality fine aggregates, and preparing internal curing aggregates to achieve humidity control, it uses a composite expansion agent to inhibit concrete shrinkage, a special water-reducing agent to adjust the concrete's workability, and an early-setting admixture to achieve high early strength, low shrinkage, and consistent setting time in the ultra-high performance concrete, thereby reducing the impact of external disturbances on road and bridge construction.

[0006] Specifically, the ultra-high performance concrete for cast-in-place wet joints resistant to disturbance of the present invention is composed of the following raw materials in parts by weight:

[0007] 540-560 parts silicate cement, 200-220 parts aluminoferrite cement, 150-200 parts ultrafine fly ash, 120-180 parts microsilica, 100-200 parts internal curing aggregate, 700-900 parts fine aggregate, 15-20 parts activated calcium oxide, 5-10 parts activated magnesium oxide, 24-30 parts polycarboxylate superplasticizer, 0.1-0.3 parts lithium carbonate, 1.8-2.2 parts boric acid, 150-200 parts steel fiber, and 290-350 parts water.

[0008] This invention uses silicate cement and aluminoferrite cement as composite cement, which has certain micro-expansion characteristics. The ultrafine fly ash and microsilica powder have high activity, small particle size, and large specific surface area. Activated calcium oxide and activated magnesium oxide are used as composite expansion agents, and the cementitious material generates continuous compensating shrinkage during the setting process and the hydration process after final setting.

[0009] Preferably, the preparation process of the internal curing aggregate is as follows:

[0010] a. Mix 80-90 parts of porous silicate powder and 5-10 parts of sodium carbonate evenly, calcine at high temperature, maintain the temperature, and then rapidly cool to obtain modified porous silicate powder.

[0011] b. Mix 50-75 parts of steel slag powder, 15-35 parts of modified porous silicate powder, 8-15 parts of silicate cement, 2-5 parts of microsilica, and 0.03-0.05 parts of SAP particles evenly to obtain a powder.

[0012] c. Add 95-105 parts of powder to a cylindrical granulator, slowly spray in 18-25 parts of water, and granulate by rotation to obtain a 2.36-4.75mm blank.

[0013] d. Carbonize and cure the billet, soak it in water for curing, and then dry it to obtain the final product.

[0014] This invention prepares internally cured aggregates that achieve a balance between porosity and strength. Combined with the water absorption, retention and release properties of SAP particles, it enables self-curing during the later curing process of ultra-high performance concrete, reducing the drying shrinkage of the concrete.

[0015] Preferably, the polycarboxylate superplasticizer is polymerized from monomers of 10-15 parts acrylic acid, 70-90 parts methyl allyl alcohol polyoxyethylene ether, 3-8 parts 2-acrylamido-2-methylpropanesulfonic acid, and 2-7 parts cyclodextrin monocis-butenedioate.

[0016] The polycarboxylate superplasticizer of this invention can adjust the rheological properties of the slurry, maintain the fluidity of concrete while improving the dispersion effect of the internal curing aggregate, and has a good synergistic effect with boric acid. For the cementitious material system of this invention, it can extend the initial setting time of concrete while shortening the final setting time, and achieve early strength of concrete in combination with lithium carbonate, reducing the impact of external disturbances on road and bridge construction.

[0017] Preferably, the silicate cement is P·Ⅱ52.5 cement with a specific surface area > 380m². 2 / kg.

[0018] Preferably, the specific surface area of ​​the ultrafine fly ash is ≥1500 m². 2 / kg, 28d activity index ≥100%.

[0019] Preferably, the microsilica powder is monocrystalline microsilica powder with a specific surface area ≥18000 m². 2 / kg, SiO2 content ≥96%.

[0020] Preferably, the steel fiber is copper-plated straight steel fiber with a diameter of 0.21-0.23 mm and a length of 12-14 mm.

[0021] Preferably, in the internal maintenance aggregate preparation process, the porous silicate powder in step a is diatomaceous earth, containing 88.95% SiO2 by mass, with an average pore diameter of 56.2 nm, a particle size ≤0.075 mm, and a loss on ignition of 0.39%.

[0022] Preferably, in the internal curing aggregate preparation process, step a involves heating to 900-1100℃ for calcination and holding for 1-2 hours.

[0023] Preferably, in the internal curing aggregate preparation process, the SAP particle size in step b is ≤0.15mm.

[0024] Preferably, in the internal curing aggregate preparation process, the carbonization pressure in step d, carbonization curing, is 0.1-0.5 MPa, the temperature is 20-24℃, the relative humidity is 50-70%, and the carbonization curing time is 24-48 h.

[0025] Preferably, in the internal curing aggregate preparation process, the soaking and curing time in step d is 24-30 hours.

[0026] This invention also relates to a method for preparing the above-mentioned ultra-high performance concrete for cast-in-place wet joints resistant to disturbance, specifically including the following steps:

[0027] 1) Weigh each raw material according to its weight.

[0028] 2) Add the internal curing aggregate and some water to the mixer and mix to pre-wet.

[0029] 3) Add silicate cement, aluminoferrate cement, ultrafine fly ash, microsilica powder, fine aggregate, activated calcium oxide, and activated magnesium oxide to the mixer and mix thoroughly. Add steel fibers and mix thoroughly.

[0030] 4) Mix the polycarboxylate superplasticizer, lithium carbonate, boric acid, and remaining water thoroughly to obtain an additive solution.

[0031] 5) Add the additive solution to the mixer and mix thoroughly to obtain a slurry.

[0032] 6) The slurry is then molded and cured to obtain the final product.

[0033] This invention has the following technical advantages:

[0034] 1. The ultra-high performance concrete of this invention has low total shrinkage and drying shrinkage, which can effectively reduce problems such as insufficient interfacial bond strength caused by auto-shrinkage during pouring and shrinkage cracking during later curing and operation.

[0035] 2. This invention achieves ultra-high early strength in concrete through raw material formulation and controls the difference between initial and final setting times, facilitating construction and ensuring structural quality after construction. It also results in high later-stage mechanical properties.

[0036] 3. This invention is simple to construct, highly practical, and can be used for in-situ pouring of wet joints, with strong resistance to disturbance. Detailed Implementation

[0037] To characterize the technical effects of this invention, concrete was prepared and its properties were tested. During the experiment, the silicate cement used was P·Ⅱ52.5 cement with a specific surface area of ​​395 m². 2 / kg, the specific surface area of ​​ultrafine fly ash is 1600m² 2 / kg, with a 28-day activity index of 105%, the microsilica powder is monocrystalline microsilica powder with a specific surface area of ​​18000 m². 2 / kg, SiO2 content is 96%, steel fiber is copper-plated straight steel fiber with diameter of 0.21-0.23mm and length of 12-14mm, porous silicate powder is diatomaceous earth powder from Linjiang City, Jilin Province, with SiO2 mass fraction of 88.95%, average pore diameter of 56.2nm, particle size ≤0.075mm, and loss on ignition of 0.39%.

[0038] Example 1

[0039] Concrete, characterized in that it is composed of the following raw materials in parts by weight:

[0040] 560 parts silicate cement, 210 parts aluminoferrite cement, 170 parts ultrafine fly ash, 140 parts microsilica, 200 parts internal curing aggregate, 800 parts fine aggregate, 17 parts activated calcium oxide, 5 parts activated magnesium oxide, 28 parts polycarboxylate superplasticizer, 0.2 parts lithium carbonate, 1.9 parts boric acid, 160 parts steel fiber, and 340 parts water.

[0041] The preparation process of the internal curing aggregate is as follows:

[0042] a. Mix 80 parts of porous silicate powder and 7 parts of sodium carbonate evenly, heat to 1000℃ and calcine, hold at that temperature for 1.5 hours, then rapidly cool to obtain modified porous silicate powder.

[0043] b. Mix 65 parts of steel slag powder, 25 parts of modified porous silicate powder, 12 parts of silicate cement, 3 parts of microsilica powder, and 0.05 parts of SAP particles evenly to obtain a powder.

[0044] c. Add 100 parts of powder to a cylindrical granulator, slowly spray in 25 parts of water, and granulate by rotation to obtain a blank with a diameter of 2.36-4.75 mm.

[0045] d. Carbonize and cure the billet in an environment with a pressure of 0.3 MPa, a temperature of 20℃, and a relative humidity of 60% for 24 hours, then soak and cure it for 24 hours, and finally dry it to obtain the final product.

[0046] The polycarboxylate superplasticizer is polymerized from monomers of 15 parts acrylic acid, 85 parts methyl allyl alcohol polyoxyethylene ether, 5 parts 2-acrylamido-2-methylpropanesulfonic acid, and 6 parts cyclodextrin monocis-butenedioate.

[0047] Tests showed that the initial setting time of the concrete was 68 minutes, the final setting time was 115 minutes, the 1-day compressive strength was 97.8 MPa, the 3-day compressive strength was 131.2 MPa, the 28-day compressive strength was 149.6 MPa, and the total shrinkage was 450 × 10⁻⁶ MPa. -6 Shrinkage 251×10 -6 .

[0048] Example 2

[0049] Concrete, characterized in that it is composed of the following raw materials in parts by weight:

[0050] 560 parts silicate cement, 200 parts aluminoferrite cement, 170 parts ultrafine fly ash, 160 parts microsilica, 190 parts internal curing aggregate, 810 parts fine aggregate, 18 parts activated calcium oxide, 7 parts activated magnesium oxide, 30 parts polycarboxylate superplasticizer, 0.2 parts lithium carbonate, 2.1 parts boric acid, 170 parts steel fiber, and 340 parts water.

[0051] The preparation process of the internal curing aggregate is as follows:

[0052] a. Mix 90 parts of porous silicate powder and 10 parts of sodium carbonate evenly, heat to 1000℃ and calcine, hold at that temperature for 1.5 hours, then rapidly cool to obtain modified porous silicate powder.

[0053] b. Mix 70 parts of steel slag powder, 30 parts of modified porous silicate powder, 8 parts of silicate cement, 3 parts of microsilica powder, and 0.05 parts of SAP particles evenly to obtain a powder.

[0054] c. Add 105 parts of powder to a cylindrical granulator, slowly spray in 22 parts of water, and granulate by rotation to obtain a blank with a diameter of 2.36-4.75 mm.

[0055] d. Carbonize and cure the billet in an environment with a pressure of 0.3 MPa, a temperature of 20℃, and a relative humidity of 60% for 24 hours, then soak and cure it for 24 hours, and finally dry it to obtain the final product.

[0056] The polycarboxylate superplasticizer is polymerized from 13 parts acrylic acid, 90 parts methyl allyl alcohol polyoxyethylene ether, 7 parts 2-acrylamido-2-methylpropanesulfonic acid, and 4 parts cyclodextrin monocis-butenedioate as monomers.

[0057] Testing revealed that the concrete's initial setting time was 80 minutes, final setting time was 133 minutes, 1-day compressive strength was 98.1 MPa, 3-day compressive strength was 136.4 MPa, 28-day compressive strength was 152.3 MPa, and total shrinkage was 443 × 10⁻⁶ MPa. -6Shrinkage 246×10 -6 .

[0058] Comparative Example 1

[0059] Concrete, characterized in that it is composed of the following raw materials in parts by weight:

[0060] 560 parts silicate cement, 210 parts aluminoferrite cement, 170 parts ultrafine fly ash, 140 parts microsilica, 1000 parts fine aggregate, 17 parts activated calcium oxide, 5 parts activated magnesium oxide, 28 parts polycarboxylate superplasticizer, 0.2 parts lithium carbonate, 1.9 parts boric acid, 160 parts steel fiber, and 340 parts water.

[0061] The polycarboxylate superplasticizer is polymerized from monomers of 15 parts acrylic acid, 85 parts methyl allyl alcohol polyoxyethylene ether, 5 parts 2-acrylamido-2-methylpropanesulfonic acid, and 6 parts cyclodextrin monocis-butenedioate.

[0062] Tests showed that the initial setting time of the concrete was 75 minutes, the final setting time was 133 minutes, the 1-day compressive strength was 94.5 MPa, the 3-day compressive strength was 102.4 MPa, the 28-day compressive strength was 119.7 MPa, and the total shrinkage was 1340 × 10⁻⁶ MPa. -6 Shrinkage 760×10 -6 .

[0063] Comparative Example 2

[0064] Concrete, characterized in that it is composed of the following raw materials in parts by weight:

[0065] 560 parts silicate cement, 210 parts aluminoferrite cement, 170 parts ultrafine fly ash, 140 parts microsilica, 190 parts 2.36-4.75mm ceramsite sand, 5 parts SAP particles, 800 parts fine aggregate, 17 parts activated calcium oxide, 5 parts activated magnesium oxide, 28 parts polycarboxylate superplasticizer, 0.2 parts lithium carbonate, 1.9 parts boric acid, 160 parts steel fiber, and 340 parts water.

[0066] The polycarboxylate superplasticizer is polymerized from monomers of 15 parts acrylic acid, 85 parts methyl allyl alcohol polyoxyethylene ether, 5 parts 2-acrylamido-2-methylpropanesulfonic acid, and 6 parts cyclodextrin monocis-butenedioate.

[0067] Testing revealed that the concrete's initial setting time was 69 minutes, final setting time was 128 minutes, 1-day compressive strength was 81.7 MPa, 3-day compressive strength was 92.4 MPa, 28-day compressive strength was 109.0 MPa, and total shrinkage was 910 × 10⁻⁶ MPa. -6 Shrinkage 495×10 -6 .

[0068] Comparative Example 3

[0069] Concrete, characterized in that it is composed of the following raw materials in parts by weight:

[0070] 560 parts silicate cement, 210 parts aluminoferrite cement, 170 parts ultrafine fly ash, 140 parts microsilica, 200 parts internal curing aggregate, 800 parts fine aggregate, 17 parts activated calcium oxide, 5 parts activated magnesium oxide, 28 parts polycarboxylate superplasticizer, 0.2 parts lithium carbonate, 1.9 parts boric acid, 160 parts steel fiber, and 340 parts water.

[0071] The preparation process of the internal curing aggregate is as follows:

[0072] a. Mix 80 parts of porous silicate powder and 7 parts of sodium carbonate evenly, heat to 1000℃ and calcine, hold at that temperature for 1.5 hours, then rapidly cool to obtain modified porous silicate powder.

[0073] b. Mix 65 parts of steel slag powder, 25 parts of modified porous silicate powder, 12 parts of silicate cement, 3 parts of microsilica powder, and 0.05 parts of SAP particles evenly to obtain a powder.

[0074] c. Add 100 parts of powder to a cylindrical granulator, slowly spray in 25 parts of water, and granulate by rotation to obtain a blank with a diameter of 2.36-4.75 mm.

[0075] d. Carbonize and cure the billet in an environment with a pressure of 0.3 MPa, a temperature of 20℃, and a relative humidity of 60% for 24 hours, then soak and cure it for 24 hours, and finally dry it to obtain the final product.

[0076] The polycarboxylate superplasticizer is polymerized from 15 parts acrylic acid, 90 parts methyl allyl alcohol polyoxyethylene ether, and 7 parts 2-acrylamido-2-methylpropanesulfonic acid as monomers.

[0077] Tests showed that the initial setting time of the concrete was 122 min, the final setting time was 215 min, the 1-day compressive strength was 87.6 MPa, the 3-day compressive strength was 113.2 MPa, the 28-day compressive strength was 122.7 MPa, and the total shrinkage was 760 × 10⁻⁶ MPa. -6 Shrinkage 435×10 -6 .

[0078] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A type of ultra-high performance concrete for cast-in-place wet joints resistant to disturbance, characterized in that, Composed of the following raw materials in parts by weight: 540-560 parts silicate cement, 200-220 parts aluminoferrite cement, 150-200 parts ultrafine fly ash, 120-180 parts microsilica, 100-200 parts internal curing aggregate, 700-900 parts fine aggregate, 15-20 parts activated calcium oxide, 5-10 parts activated magnesium oxide, 24-30 parts polycarboxylate superplasticizer, 0.1-0.3 parts lithium carbonate, 1.8-2.2 parts boric acid, 150-200 parts steel fiber, and 290-350 parts water. The preparation process of the internal curing aggregate is as follows: a. Mix 80-90 parts of porous silicate powder and 5-10 parts of sodium carbonate evenly, calcine at high temperature, maintain the temperature, and then rapidly cool to obtain modified porous silicate powder. b. Mix 50-75 parts of steel slag powder, 15-35 parts of modified porous silicate powder, 8-15 parts of silicate cement, 2-5 parts of microsilica, and 0.03-0.05 parts of SAP particles evenly to obtain a powder. c. Add 95-105 parts of powder to a cylindrical granulator, slowly spray in 18-25 parts of water, and granulate by rotation to obtain a 2.36-4.75mm blank. d. Carbonize and cure the billet, soak it in water for curing, and then dry it to obtain the final product. The polycarboxylate superplasticizer is polymerized from monomers of 10-15 parts acrylic acid, 70-90 parts methyl allyl alcohol polyoxyethylene ether, 3-8 parts 2-acrylamido-2-methylpropanesulfonic acid, and 2-7 parts cyclodextrin monocis-butenedioate.

2. The ultra-high performance concrete for cast-in-place wet joints with anti-disturbance properties as described in claim 1, characterized in that, The silicate cement is P·Ⅱ52.5 cement with a specific surface area >380m². 2 / kg.

3. The ultra-high performance concrete for cast-in-place wet joints with anti-disturbance properties as described in claim 1, characterized in that, The ultrafine fly ash has a specific surface area ≥1500m² 2 / kg, 28d activity index ≥100%.

4. The ultra-high performance concrete for cast-in-place wet joints with anti-disturbance properties as described in claim 1, characterized in that, The microsilica powder is monocrystalline microsilica powder with a specific surface area ≥18000m². 2 / kg, SiO2 content ≥96%.

5. The ultra-high performance concrete for cast-in-place wet joints with anti-disturbance properties as described in claim 1, characterized in that, The steel fiber is a copper-plated straight steel fiber with a diameter of 0.21-0.23 mm and a length of 12-14 mm.

6. The ultra-high performance concrete for cast-in-place wet joints with anti-disturbance properties as described in claim 1, characterized in that, In the internal curing aggregate preparation process, the porous silicate powder in step a is diatomaceous earth, containing 88.95% SiO2 by mass, with an average pore diameter of 56.2 nm, a particle size ≤0.075 mm, and a loss on ignition of 0.39%.

7. The ultra-high performance concrete for cast-in-place wet joints with anti-disturbance properties as described in claim 1, characterized in that, In the internal curing aggregate preparation process, the SAP particle size in step b is ≤0.15mm.

8. The ultra-high performance concrete for cast-in-place wet joints with anti-disturbance properties as described in claim 1, characterized in that, In the internal curing aggregate preparation process, the carbonization pressure in step d, carbonization curing, is 0.1-0.5 MPa, the temperature is 20-24℃, the relative humidity is 50-70%, and the carbonization curing time is 24-48 h.

9. The ultra-high performance concrete for cast-in-place wet joints with anti-disturbance properties as described in claim 1, characterized in that, In the internal curing aggregate preparation process, the soaking and curing time in step d is 24-30 hours.

10. The method for preparing ultra-high performance concrete for cast-in-place wet joints with anti-disturbance properties according to any one of claims 1-9, characterized in that, Includes the following steps: 1) Weigh each raw material according to its weight. 2) Add the internal curing aggregate and some water to the mixer and mix to pre-wet. 3) Add silicate cement, aluminoferrate cement, ultrafine fly ash, microsilica powder, fine aggregate, activated calcium oxide, and activated magnesium oxide to the mixer and mix thoroughly. Add steel fibers and mix thoroughly. 4) Mix the polycarboxylate superplasticizer, lithium carbonate, boric acid, and remaining water thoroughly to obtain an additive solution. 5) Add the additive solution to the mixer and mix thoroughly to obtain a slurry. 6) The slurry is then molded and cured to obtain the final product.