An ultra-high performance concrete for construction and a method for preparing a concrete slab

Abstract

The method relates to the technical field of building materials, and discloses a kind of super high performance concrete for building and concrete slab preparation method, super high performance concrete includes the following components: cementitious material: 600~850 parts;Silica fume: 150~200 parts;Fine aggregate: coarse aggregate 300~360 parts;Synthetic anti-cracking fiber: 5~20 parts;Admixture: polycarboxylic acid high performance water reducing agent 15~35 parts, defoaming agent 0.5~3 parts;Titanium dioxide: 5~15 parts;Water: 150~200 parts.By using ordinary Portland cement, silica fume, quartz sand aggregate, polypropylene fiber, polycarboxylic acid high performance water reducing agent, defoaming agent, titanium dioxide, water, and adding nano silicon dioxide and slow-release antibacterial agent to prepare super high performance concrete, high toughness, high stability, high adaptability, high compressive strength, high fluidity and antibacterial performance of super high performance concrete are obtained.

Description

TECHNICAL FIELD

[0001] The method relates to the technical field of building materials, in particular to a kind of super high performance concrete for building and concrete slab preparation method. BACKGROUND

[0002] The super high performance concrete is prepared from ordinary Portland cement, silica fume, quartz sand aggregate, synthetic anti-cracking fiber, water reducing agent, defoaming agent, titanium dioxide and water, has high strength and durability, and is widely used in the preparation of building exterior wall curtain wall plate. In the prior art, the super high performance concrete is formed into a uniform mixture by forced mixing, and is cast into a mold using a steel or aluminum alloy mold. After curing, the curtain wall plate is obtained, and the surface can form a simple decorative pattern through the mold to meet the strength and aesthetic requirements of the building exterior wall.

[0003] However, the super high performance concrete formula in the prior art lacks optimized components, resulting in insufficient compressive strength and mixture fluidity, which makes it difficult to meet the molding requirements of complex decorative patterns, limiting the application of exterior curtain wall plates in high strength and complex modeling. SUMMARY

[0004] To overcome the shortcomings of the prior art, the method provides a kind of super high performance concrete for building and concrete slab preparation method, which solves the problem of lack of optimized components in the super high performance concrete formula in the prior art, resulting in insufficient compressive strength and mixture fluidity.

[0005] To achieve the above purpose, the method is implemented by the following technical scheme: a kind of super high performance concrete for building, by mass fraction, includes the following components:

[0006] Binder: 600-850 parts, ordinary Portland cement is selected, and the strength grade is not less than 42.5 grade;

[0007] Silica fume: 150-200 parts, average particle size 0.1-0.2 μm;

[0008] Aggregate: coarse aggregate 300-360 parts, particle size 0.6-1.2 mm quartz sand; medium aggregate 300-360 parts, particle size 0.3-0.6 mm quartz sand; fine aggregate 150-240 parts, particle size 0.1-0.3 mm quartz sand;

[0009] Synthetic anti-cracking fiber: 5-20 parts, length 6-12 mm;

[0010] Admixture: polycarboxylic acid high performance water reducing agent 15-35 parts, defoaming agent 0.5-3 parts;

[0011] Titanium dioxide: 5-15 parts;

[0012] Water: 150-200 parts, water-binder ratio 0.18-0.22.

[0013] Through the above technical solution, by using 600-850 parts of ordinary silicate cement, 150-200 parts of silica fume, quartz sand aggregate, 5-20 parts of synthetic crack-resistant fiber, 15-35 parts of polycarboxylate high-performance water-reducing agent, 0.5-3 parts of defoamer, 5-15 parts of titanium dioxide, and 150-200 parts of water, and controlling the water-cement ratio to 0.18-0.22, the cementitious material and silica fume form a high-strength matrix, the quartz sand aggregate fills the dense structure, and the synthetic crack-resistant fiber improves the tensile strength. Therefore, ultra-high performance concrete with a compressive strength of over 120 MPa and an elongation of over 500 mm is obtained, which is suitable for the preparation of exterior wall curtain wall panels.

[0014] Preferably, the additive further includes 1-5 parts of nano-silica with a particle size of 10-50 nm and a specific surface area of ​​200-300 m² / g; and 0.5-2 parts of a slow-release antibacterial agent, preferably a quaternary ammonium salt, with a slow-release period of 6-12 months.

[0015] By using the above technical solution, by adding 1 to 5 parts of nano-silica with a particle size of 10 to 50 nm and 0.5 to 2 parts of slow-release antibacterial agent and quaternary ammonium salt to the formula, the nano-silica fills the micropores and enhances the curing performance, and the slow-release antibacterial agent provides antibacterial function. Therefore, ultra-high performance concrete with compressive strength increased to more than 125 MPa and long-term antibacterial performance is obtained.

[0016] Preferably, the synthetic crack-resistant fiber is a polypropylene fiber with a diameter of 0.02 to 0.2 mm.

[0017] Through the above technical solution, polypropylene fibers with a length of 6-12 mm and a diameter of 0.02-0.2 mm are selected as synthetic crack-resistant fibers. The fibers are uniformly dispersed in the matrix to enhance tensile strength. Therefore, ultra-high performance concrete with reduced cracking is obtained, which is suitable for exterior wall curtain wall panels.

[0018] Preferably, the titanium dioxide is rutile titanium dioxide with a particle size of 0.2~0.3μm; the polycarboxylate high-performance water-reducing agent has a solid content of 20%~30% and a water reduction rate of 25%~35%.

[0019] Through the above technical solution, by using rutile titanium dioxide with a particle size of 0.2~0.3μm and polycarboxylate high-performance water-reducing agent with a solid content of 20%~30%, the rutile titanium dioxide improves the surface whiteness and the water-reducing agent optimizes the fluidity of the mixture, thus obtaining ultra-high performance concrete with an extension of more than 550mm and high surface whiteness, which is suitable for complex pattern molding.

[0020] A method for preparing ultra-high performance concrete slabs for construction includes the following steps:

[0021] S1. Fix a silicone plate with a thickness of 2-5mm and a hardness of Shore A30-50 to the bottom of a steel or aluminum alloy mold. Carve decorative patterns on the surface with a pattern depth of 0.5-2mm.

[0022] S2. Using a forced single-shaft concrete mixer, dry mix the cementitious materials, silica fume, titanium dioxide, and admixtures for 1-3 minutes at a speed of 40-60 rpm; add fine aggregates and mix for 0.5-1.5 minutes; add water, polycarboxylate superplasticizer, and defoamer, and mix for 3-5 minutes at a speed of 80-100 rpm; add synthetic crack-resistant fibers and mix for 10-20 minutes at a speed of 60-80 rpm, with a spread of 500-600 mm.

[0023] S3. Use a bucket to pour ultra-high performance concrete and vibrate for 20-30 seconds; spray the surface with water retention and cover with plastic film.

[0024] S4. Curing at 20~25℃ and 90%~95% relative humidity for 20~28 hours until the compressive strength is ≥30MPa, then demolding; steam curing for 6~8 days at 60~75℃ and 90%~95% humidity.

[0025] Through the above technical solution, by fixing and engraving a silicone plate at the bottom of the mold, with a thickness of 2-5mm and a hardness of Shore A 30-50, and engraving patterns on the surface with a depth of 0.5-2mm, using forced mixing to prepare ultra-high performance concrete with a spread of 500-600mm, pouring and vibrating for 20-30 seconds using a bucket, spraying water on the surface to retain moisture and covering it with a plastic film, curing for 20-28 hours, demolding after the compressive strength reaches 30MPa, steam curing for 6-8 days at a temperature of 60-75℃, the engraved silicone plate forms a precise pattern template, the mixing ensures uniformity of the mixture, and the pouring and curing promote strength, thus obtaining a curtain wall panel with a clear surface pattern, no peeling defects, and a compressive strength of not less than 120MPa.

[0026] Preferably, in step S1, before fixing the engraved silicone plate, the engraved silicone plate undergoes dynamic temperature control pretreatment. In a temperature control chamber, the initial temperature is maintained at 28~32℃ for 5~10 minutes, the temperature is increased to 48~52℃ and maintained for 10~15 minutes, and the temperature is decreased to 18~22℃ and maintained for 5~10 minutes. This cycle is repeated 2~3 times, with a total processing time of 30~40 minutes. The temperature control chamber has a power of 2~5kW, a temperature control accuracy of ±1~2℃, a heating rate of 2~3℃ / min, and a cooling rate of 2~3℃ / min.

[0027] Through the above technical solution, dynamic temperature control pretreatment is performed on the engraved silicone plate. The temperature control box has a power of 2~5kW and a temperature control accuracy of ±1~2℃. The temperature is maintained at 28~32℃ for 5~10 minutes, 48~52℃ for 10~15 minutes, and 18~22℃ for 5~10 minutes, and this cycle is repeated 2~3 times. The pretreatment forms a micron-level adsorption layer, which enhances the interfacial adhesion with concrete. Therefore, curtain wall panels with clearer surface patterns and fewer demolding defects are obtained.

[0028] Preferably, in step S3, layered pouring and zoned vibration are adopted. The first layer of ultra-high performance concrete accounts for 60% to 70% of the total thickness, and is vibrated for 20 to 30 seconds at a frequency of 40 to 60 Hz. The second layer of ultra-high performance concrete accounts for 30% to 40% of the total thickness, with a titanium dioxide content of 8 to 15 parts, and is vibrated for 10 to 15 seconds at a frequency of 50 to 70 Hz. The mold is divided into 4 to 6 vibration zones, with a vibration frequency of 40 to 60 Hz in the central zone and 50 to 70 Hz in the edge zone. The vibration equipment power is 3 to 5 kW, and the area of ​​each zone is 0.5 to 2 m².

[0029] Through the above technical solution, due to the use of layered casting, the first layer accounts for 60% to 70% of the thickness, is vibrated for 20 to 30 seconds at a frequency of 40 to 60 Hz, and the second layer accounts for 30% to 40% of the thickness, is vibrated for 10 to 15 seconds at a frequency of 50 to 70 Hz. The mold is divided into 4 to 6 vibration zones, with a center frequency of 40 to 60 Hz and an edge frequency of 50 to 70 Hz. Layered casting ensures uniform material distribution, and zoned vibration improves the consistency of density. Therefore, curtain wall panels with high pattern accuracy and uniform surface are obtained.

[0030] Preferably, in step S1, the pattern area of ​​the engraved silicone plate occupies 30% to 80% of the surface of the silicone plate, and is fixed by bolts or magnetic fixing devices with a spacing of 50 to 100 mm between the fixing devices, and the fit deviation between the mold and the silicone plate is ≤0.1 mm.

[0031] Through the above technical solution, since the area of ​​the engraved silicone plate pattern occupies 30% to 80% of the surface, and the fixing device is fixed with bolts or magnetic attraction at a spacing of 50 to 100 mm, the fitting deviation is ≤0.1 mm. The fixing device ensures that the silicone plate and the mold are tightly fitted, and the pattern template provides precise molding. Therefore, a curtain wall panel with high pattern molding accuracy and no offset is obtained.

[0032] Preferably, in step S4, the steam curing is carried out in stages: the temperature is 58-62℃ for the first 2-3 days and 73-77℃ for the next 3-5 days. The power of the steam curing chamber is 10-20kW, the temperature control accuracy is ±1-2℃, and the humidity is 90%-95%.

[0033] Through the above technical solution, the steam curing is carried out in stages. The temperature is 58~62℃ for the first 2~3 days and 73~77℃ for the next 3~5 days. The power of the curing box is 10~20kW and the temperature control accuracy is ±1~2℃. The staged curing optimizes the strength development and stabilizes the curing environment. Therefore, curtain wall panels with a compressive strength of over 120MPa and a stable surface are obtained.

[0034] Preferably, in step S3, the interval between the first and second layers of the layered pouring is 8 to 12 minutes, the bucket capacity is 0.3 to 0.8 m³, the pouring speed is 0.5 to 1.0 m³ / h, the surface spray water retention is 0.1 to 0.2 L / m², and the plastic film thickness is 0.05 to 0.1 mm.

[0035] Through the above technical solution, due to the layered pouring interval of 8 to 12 minutes, the bucket capacity of 0.3 to 0.8 m³, the pouring speed of 0.5 to 1.0 m³ / h, the surface spray water retention of 0.1 to 0.2 L / m², the plastic film thickness of 0.05 to 0.1 mm, the interval control of interlayer bonding, and the spray water retention to maintain surface humidity, a curtain wall panel with tight interlayer bonding and no surface cracks is obtained.

[0036] This method provides a method for preparing ultra-high performance concrete and concrete slabs for construction. It has the following beneficial effects:

[0037] 1. This method uses ordinary silicate cement, silica fume, quartz sand aggregate, polypropylene fiber, polycarboxylate superplasticizer, defoamer, titanium dioxide, and water, and adds nano-silica and slow-release antibacterial agent to formulate ultra-high performance concrete. The cementitious materials and silica fume form a high-strength matrix, the quartz sand aggregate ensures a dense structure, the polypropylene fiber enhances tensile strength, the superplasticizer and defoamer optimize fluidity, the nano-silica fills the micropores, and the slow-release antibacterial agent provides antibacterial function. Therefore, ultra-high performance concrete with high compressive strength, high fluidity and antibacterial properties is obtained.

[0038] This method uses a carved silicone plate fixed to the bottom of the mold, with decorative patterns carved on the surface. Combined with dynamic temperature control pretreatment, the pretreatment involves circulating temperature rise and fall in a temperature-controlled chamber to form a micron-level adsorption layer, which enhances the interfacial adhesion with ultra-high performance concrete. The fixing device ensures that the silicone plate is tightly attached to the mold. Therefore, a curtain wall panel with clear surface decorative patterns and no peeling or corner breakage is obtained, solving the demolding defect problem in the prior art.

[0039] This method employs layered casting, with the first and second layers cast to different thicknesses. The second layer has an increased titanium dioxide content. Different frequencies are used for vibration in different areas. Layered casting ensures uniform material distribution, while vibration in different areas improves density consistency. The titanium dioxide enhances surface whiteness and gloss. Therefore, curtain wall panels with high precision in decorative pattern forming and uniform surface quality are obtained.

[0040] This method uses forced mixing to prepare ultra-high performance concrete, controls the spread, uses a bucket to pour and controls the pouring interval, sprays the surface to retain water and covers it with a plastic film, mixes to ensure the uniformity of the mixture, and optimizes the interlayer bonding and surface humidity through pouring intervals and water retention measures. Therefore, it obtains curtain wall panels with tight interlayer bonding and no surface cracks. Attached Figure Description

[0041] Figure 1 This is a flowchart of a method for preparing ultra-high performance concrete and concrete slabs for building applications. Detailed Implementation

[0042] The following is in conjunction with the appendix Figure 1 The present application will be further described in detail with reference to the embodiments.

[0043] Ultra-high performance concrete (UHPC) is widely used in building exterior curtain wall panels due to its excellent mechanical properties and durability. However, existing technologies for preparing UHPC exterior curtain wall panels have a major drawback: traditional UHPC formulations struggle to simultaneously achieve high compressive strength, high flowability, and antibacterial properties, limiting the performance of the curtain wall panels in complex pattern forming and long-term use. The root cause of this problem lies in the lack of component optimization in existing formulations that balance strength, flowability, and functionality, making it difficult to meet the comprehensive requirements of exterior curtain wall panels in terms of mechanical properties, workability, and surface antibacterial properties.

[0044] Based on this discovery, the applicant optimized the formula and conducted process experiments. Initially, by adjusting the proportions of ordinary silicate cement, silica fume, and admixtures, a formula that balanced strength and flowability was selected. Subsequently, nano-silica and slow-release antibacterial agents were introduced to verify their functional improvement. Finally, through sculpted silicone panels and layered casting experiments, the surface quality of the curtain wall panels was optimized. This technical solution is proposed based on the above research results.

[0045] Sources of raw materials, reagents, methods and equipment

[0046] To ensure that those skilled in the art can implement this method, the sources of the raw materials, reagents, methods, and equipment used in the following embodiments are clearly specified. All raw materials, reagents, and equipment are commercially available or obtainable through conventional processing and meet industrial application standards.

[0047] Raw materials and reagents

[0048] Ordinary Portland cement: Strength grade 42.5, conforming to GB175-2007 standard.

[0049] Silica fume: average particle size 0.1~0.2μm, specific surface area 200~300m² / g.

[0050] Quartz sand: coarse aggregate: particle size 0.6~1.2mm;

[0051] Medium aggregate: particle size 0.3–0.6 mm;

[0052] Fine aggregate: particle size 0.1~0.3mm.

[0053] Synthetic crack-resistant fiber: polypropylene fiber, length 6-12mm, diameter 0.02-0.2mm.

[0054] Additives: Polycarboxylate high-performance water-reducing agent: solid content 20%~30%, water reduction rate 25%~35%.

[0055] Defoamer: Nonionic.

[0056] Nano silica: Particle size 10~50nm, specific surface area 200~300m² / g.

[0057] Sustained-release antibacterial agents: quaternary ammonium salts, with a sustained-release period of 6 to 12 months.

[0058] Titanium dioxide: rutile type, particle size 0.2~0.3μm.

[0059] Water: Clean water that meets the GB5749-2006 standard.

[0060] Engraved silicone sheet: 2-5mm thick, Shore A 30-50 hardness, with decorative patterns engraved on the surface.

[0061] Release agent: Conventional concrete release agent.

[0062] Forced single-shaft concrete mixer: capacity 0.5~1.0m³, power 15~30kW.

[0063] Temperature control chamber: power 2~5kW, temperature control accuracy ±1~2℃, used for dynamic temperature control pretreatment of engraved silicone plates.

[0064] Hoisting bucket: capacity 0.3-0.8m³, equipped with flow control device.

[0065] High-frequency vibrating equipment: power 3~5kW, frequency 40~70Hz.

[0066] Steam curing chamber: power 10~20kW, temperature control accuracy ±1~2℃, humidity 90%~95%.

[0067] Steel or aluminum alloy molds: sizes from 1×1m to 4×2m, with polished inner surfaces and a surface roughness Ra≤0.8μm.

[0068] Test method:

[0069] Compressive strength test: According to GB / T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", a 150×150×150mm sample was used.

[0070] Spreadability test: According to GB / T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", duration is 90 seconds.

[0071] Surface quality inspection: Visually inspect the surface of the curtain wall panel and record the clarity of the pattern and the condition of peeling / corner breakage.

[0072] Process steps: All steps adopt conventional concrete preparation processes, and equipment operation complies with industry standards.

[0073] All the above raw materials, reagents and equipment can be obtained through market purchase or conventional processing. The testing methods are well-known in the field, ensuring full disclosure of this method.

[0074] Example 1

[0075] Raw materials: By weight, the ultra-high performance concrete formula is as follows: 700 parts of ordinary Portland cement, strength grade 42.5, conforming to GB175-2007 standard;

[0076] 180 parts of silica fume, with an average particle size of 0.15 μm and a specific surface area of ​​250 m² / g;

[0077] 330 parts coarse aggregate, quartz sand, particle size 0.6-1.2mm;

[0078] 330 parts of medium aggregate, quartz sand, particle size 0.3-0.6mm;

[0079] 200 parts fine aggregate, quartz sand, particle size 0.1-0.3 mm;

[0080] 10 parts of synthetic crack-resistant fiber, polypropylene fiber, 9mm in length and 0.1mm in diameter;

[0081] 25 parts of polycarboxylate high-performance water-reducing agent, solid content 25%, water reduction rate 30%;

[0082] 1.5 parts of defoamer, nonionic type;

[0083] Three parts of nano-silica, with a particle size of 30nm and a specific surface area of ​​250m² / g;

[0084] One part of a sustained-release antibacterial agent, a quaternary ammonium salt, with a sustained-release period of 9 months;

[0085] 10 parts of titanium dioxide, rutile type, particle size 0.25μm;

[0086] 180 parts water, conforming to GB5749-2006 standard, water-to-binder ratio 0.20.

[0087] Steps: S1. Mold Preparation and Dynamic Temperature Control Pretreatment: Select a 4×2m steel mold, polish the inner surface to a surface roughness Ra≤0.8μm, and uniformly spray a release agent with a coating thickness of 0.05mm. Fix a 3mm thick, Shore A40 hardness engraved silicone plate with a stone-like decorative pattern engraved on the surface. The pattern depth is 1mm, and the pattern area occupies 50% of the silicone plate surface. Perform dynamic temperature control pretreatment in a temperature control chamber with a power of 3kW and a temperature control accuracy of ±1℃. Maintain an initial temperature of 30℃ for 8 minutes, then raise the temperature to 50℃ at a rate of 2.5℃ / min and maintain for 12 minutes. Then lower the temperature to 20℃ at a rate of 2.5℃ / min and maintain for 8 minutes. Repeat this cycle twice for a total treatment time of 36 minutes. Use bolt fixing devices with a spacing of 80mm to fix the engraved silicone plate, ensuring a fit deviation ≤0.1mm.

[0088] S2. Preparation of Ultra-High Performance Concrete: A forced-drive single-shaft concrete mixer with a capacity of 0.8 m³ and a power of 20 kW was used. Ordinary Portland cement, silica fume, titanium dioxide, nano-silica, and slow-release antibacterial agent were dry-mixed for 2 minutes at 50 rpm. Coarse aggregate, medium aggregate, and fine aggregate were added and mixed for 1 minute at 50 rpm. Water, polycarboxylate superplasticizer, and defoamer were slowly added over a period of 1.5 minutes, followed by 4 minutes of mixing at 90 rpm. Synthetic crack-resistant fibers were added in four batches, with a 45-second interval between each batch, and mixed for 15 minutes at 70 rpm. The spread was tested according to GB / T50080-2016, with a duration of 90 seconds and a spread of 550 mm.

[0089] S3. Layered Pouring and Zonal Vibration: A 0.5m³ bucket is used, with a pouring speed of 0.8m³ / h. The first layer of ultra-high performance concrete is poured to 13mm, accounting for 65% of the total thickness, with a total thickness of 20mm. Vibration is performed for 25 seconds at a frequency of 50Hz using a 4kW high-frequency vibrator. The second layer of ultra-high performance concrete is poured to 7mm, accounting for 35% of the total thickness, with a titanium dioxide content of 12 parts per cubic centimeter. Vibration is performed for 12 seconds at a frequency of 60Hz. The mold is divided into four vibration zones, each 1m² in area. The central zone is vibrated at a frequency of 50Hz, and the edge zones at a frequency of 60Hz. There is a 10-minute interval between the first and second layers. The surface is sprayed with 0.15L / m² of water for moisture retention and covered with a 0.08mm thick plastic film.

[0090] S4. Curing and Demolding: The panels are left to cure statically for 24 hours at 22℃ and 92% relative humidity. The compressive strength is then tested and, according to GB / T50081-2019, reaches 32MPa. Demolding is then performed using mechanical lifting equipment at a speed of 0.15m / min. After demolding, the curtain wall panels are placed in a steam curing chamber with a power of 15kW, a temperature control accuracy of ±1.5℃, and a humidity of 92%. Curing is carried out for 7 days, with the temperature at 60℃ for the first 3 days and 75℃ for the following 4 days.

[0091] Result: The exterior wall curtain wall panels obtained have clear stone-like patterns on the surface, with no peeling or chipping.

[0092] Example 2

[0093] Raw materials: By weight, the ultra-high performance concrete formula is as follows: 850 parts of ordinary Portland cement, strength grade 42.5, conforming to GB175-2007 standard;

[0094] 200 parts of silica fume, average particle size 0.2μm, specific surface area 300m² / g;

[0095] 360 parts coarse aggregate, quartz sand, particle size 0.6-1.2mm;

[0096] 360 parts of medium aggregate, quartz sand, particle size 0.3-0.6mm;

[0097] 240 parts fine aggregate, quartz sand, particle size 0.1-0.3 mm;

[0098] 20 parts of synthetic crack-resistant fiber, polypropylene fiber, 12mm in length and 0.2mm in diameter;

[0099] 35 parts of polycarboxylate high-performance water-reducing agent, solid content 30%, water reduction rate 35%;

[0100] 3 parts defoamer, nonionic type;

[0101] Five parts of nano-silica, with a particle size of 50 nm and a specific surface area of ​​300 m² / g;

[0102] Two portions of sustained-release antibacterial agent, quaternary ammonium salts, with a sustained-release period of 12 months;

[0103] 15 parts of titanium dioxide, rutile type, particle size 0.3 μm

[0104] 200 parts water, conforming to GB5749-2006 standard, water-to-binder ratio 0.18.

[0105] Steps: S1. Mold Preparation and Dynamic Temperature Control Pretreatment: Select a 3×1.5m aluminum alloy mold, polish the inner surface to a surface roughness Ra≤0.8μm, and spray with a release agent to a coating thickness of 0.08mm. Fix a 5mm thick, Shore A50 hardness engraved silicone plate with a geometric pattern engraved on the surface. The pattern depth is 2mm, and the pattern area occupies 80% of the silicone plate surface. Perform dynamic temperature control pretreatment in a temperature control chamber with a power of 5kW and a temperature control accuracy of ±1℃. Maintain an initial temperature of 32℃ for 5 minutes, then raise the temperature to 52℃ at a rate of 3℃ / min and maintain for 10 minutes. Then lower the temperature to 22℃ at a rate of 3℃ / min and maintain for 5 minutes. Repeat this cycle 3 times for a total treatment time of 40 minutes. Use a magnetic fixing device with a spacing of 50mm to fix the engraved silicone plate, ensuring a fit deviation ≤0.1mm.

[0106] S2. Preparation of Ultra-High Performance Concrete: A forced-drive single-shaft concrete mixer with a capacity of 1.0 m³ and a power of 30 kW was used. Ordinary Portland cement, silica fume, titanium dioxide, nano-silica, and slow-release antibacterial agent were dry-mixed for 3 minutes at 40 rpm. Coarse aggregate, medium aggregate, and fine aggregate were added and mixed for 1.5 minutes at 40 rpm. Water, polycarboxylate superplasticizer, and defoamer were slowly added over a period of 2 minutes, followed by 5 minutes of mixing at 80 rpm. Synthetic crack-resistant fibers were added in 5 batches, with a 60-second interval between each batch, and mixed for 20 minutes at 60 rpm. The spread was tested for 90 seconds, achieving a spread of 600 mm.

[0107] S3. Layered Pouring and Zonal Vibration: A 0.8m³ bucket is used, with a pouring speed of 1.0m³ / h. The first layer of ultra-high performance concrete is poured to 18mm, accounting for 70% of the total thickness, with a total thickness of 25mm. Vibration is performed for 30 seconds at a frequency of 60Hz using a 5kW high-frequency vibrator. The second layer of ultra-high performance concrete is poured to 7mm, accounting for 30% of the total thickness, with a titanium dioxide content of 15 parts per cubic centimeter. Vibration is performed for 15 seconds at a frequency of 70Hz. The mold is divided into 6 vibration zones, each with an area of ​​0.75m². The vibration frequency is 60Hz in the central zone and 70Hz in the edge zone. There is an 8-minute interval between the first and second layers. The surface is sprayed with 0.2L / m² of water for moisture retention and covered with a 0.1mm thick plastic film.

[0108] S4. Curing and Demolding: The panels are left to cure statically for 28 hours at 20℃ and 95% relative humidity. Once the compressive strength reaches 35MPa, the panels are demolded. After demolding, the curtain wall panels are placed in a steam curing chamber with a power of 20kW, temperature control accuracy of ±1℃, and humidity of 95%. Curing is carried out for 8 days, with the temperature at 58℃ for the first 3 days and 73℃ for the following 5 days.

[0109] Result: The obtained exterior wall curtain wall panels have clear geometric texture patterns on the surface, with no peeling or corner chipping.

[0110] Example 3

[0111] Raw materials: By weight, the ultra-high performance concrete formula is as follows: 600 parts of ordinary Portland cement, strength grade 42.5, conforming to GB175-2007 standard;

[0112] 150 parts of silica fume, average particle size 0.1 μm, specific surface area 200 m² / g;

[0113] 300 parts coarse aggregate, quartz sand, particle size 0.6-1.2mm;

[0114] 300 parts of medium aggregate, quartz sand, particle size 0.3-0.6mm;

[0115] 150 parts fine aggregate, quartz sand, particle size 0.1-0.3 mm;

[0116] Five parts of synthetic crack-resistant fiber, polypropylene fiber, 6 mm in length and 0.02 mm in diameter;

[0117] 15 parts of polycarboxylate high-performance water-reducing agent, solid content 20%, water reduction rate 25%;

[0118] 0.5 parts of defoamer, nonionic type;

[0119] One part of nano-silica, with a particle size of 10nm and a specific surface area of ​​200m² / g;

[0120] 0.5 parts of a sustained-release antibacterial agent, a quaternary ammonium salt, with a sustained-release period of 6 months;

[0121] Five parts of titanium dioxide, rutile type, particle size 0.2 μm;

[0122] 150 parts water, conforming to GB5749-2006 standard, water-to-binder ratio 0.22.

[0123] Steps: S1. Mold Preparation and Dynamic Temperature Control Pretreatment: Select a 2×1m steel mold, polish the inner surface to a surface roughness Ra≤0.8μm, and spray with a release agent to a coating thickness of 0.06mm. Fix a 2mm thick, Shore A30 hardness engraved silicone plate with a wood grain decorative pattern engraved on the surface. The pattern depth is 0.5mm, and the pattern area occupies 30% of the silicone plate surface. Perform dynamic temperature control pretreatment in a temperature control chamber with a power of 2kW and a temperature control accuracy of ±2℃. Maintain an initial temperature of 28℃ for 10 minutes, then raise the temperature to 48℃ at a rate of 2℃ / min and maintain for 15 minutes. Then lower the temperature to 18℃ at a rate of 2℃ / min and maintain for 10 minutes. Repeat this cycle twice for a total treatment time of 38 minutes. Use bolt fixing devices with a spacing of 100mm to fix the engraved silicone plate, ensuring a fit deviation ≤0.1mm.

[0124] S2. Preparation of Ultra-High Performance Concrete: A forced-drive single-shaft concrete mixer with a capacity of 0.5 m³ and a power of 15 kW was used. Ordinary Portland cement, silica fume, titanium dioxide, nano-silica, and slow-release antibacterial agent were dry-mixed for 1 minute at 60 rpm. Coarse, medium, and fine aggregates were added and mixed for 0.5 minutes at 60 rpm. Water, polycarboxylate superplasticizer, and defoamer were slowly added over a period of 1 minute, followed by 3 minutes of mixing at 100 rpm. Synthetic crack-resistant fibers were added in three batches, with a 30-second interval between each batch, and mixed for 10 minutes at 80 rpm. The spread was tested for 90 seconds, achieving a spread of 500 mm.

[0125] S3. Layered Pouring and Zonal Vibration: A 0.3m³ bucket is used, with a pouring speed of 0.5m³ / h. The first layer of ultra-high performance concrete is poured to 9mm, accounting for 60% of the total thickness, with a total thickness of 15mm. Vibration is performed for 20 seconds at a frequency of 40Hz using a 3kW high-frequency vibrator. The second layer of ultra-high performance concrete is poured to 6mm, accounting for 40% of the total thickness, with 8 parts titanium dioxide. Vibration is performed for 10 seconds at a frequency of 50Hz. The mold is divided into four vibration zones, each with an area of ​​0.5m². The vibration frequency is 40Hz in the central zone and 50Hz in the edge zone. There is a 12-minute interval between the first and second layers. The surface is sprayed with 0.1L / m² of water for moisture retention and covered with a 0.05mm thick plastic film.

[0126] S4. Curing and Demolding: The panels are left to cure statically for 20 hours at 25℃ and 90% relative humidity. Once the compressive strength reaches 30MPa, the panels are demolded. After demolding, the curtain wall panels are placed in a steam curing chamber with a power of 10kW, a temperature control accuracy of ±2℃, and a humidity of 90%. Curing is carried out for 6 days, with the temperature at 62℃ for the first 2 days and 77℃ for the following 4 days.

[0127] Result: The exterior wall curtain wall panels obtained have clear wood grain patterns on the surface, with no peeling or chipping.

[0128] Comparative Example 1

[0129] Compared with Example 1, the differences are as follows: the ultra-high performance concrete formula does not contain nano-silica and slow-release antibacterial agent; in step S1, ordinary silicone board is used instead of carved silicone board and dynamic temperature control pretreatment is not performed; in step S3, single pouring is used instead of layered pouring and zoned vibration, the mold is not zoned for vibration, the vibration time is 20 seconds, the frequency is 50Hz, and the rest are the same.

[0130] Result: The obtained exterior wall curtain wall panels had unclear surface patterns and slight peeling.

[0131] Comparative Example 2

[0132] Compared with Example 2, the differences are: the ultra-high performance concrete formula does not contain nano-silica and slow-release antibacterial agent; in step S1, ordinary steel molds are used instead of carved silicone plates and dynamic temperature control pretreatment is not performed; in step S3, single pouring is used instead of layered pouring and zoned vibration, the mold is not zoned for vibration, the vibration time is 25 seconds, the frequency is 60Hz, and the rest are the same.

[0133] Result: The obtained exterior wall curtain wall panels have no pattern on the surface and have slight corner chipping.

[0134] Test example:

[0135] This experiment tested the performance of exterior wall curtain wall panel samples prepared in Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2. The tests included compressive strength, swell, and surface quality. The testing equipment included a press, a swell testing device, and visual inspection tools. The testing environment was 20–25°C and 90%–95% relative humidity. The experimental steps are as follows:

[0136] Step 1: Sample Preparation

[0137] Three exterior wall panel samples (150×150×150mm each) were taken from each of Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2 for compressive strength testing; three samples of ultra-high performance concrete mixture were also taken for scalability testing; intact curtain wall panel samples were retained for surface quality inspection. Each sample was labeled with a number to ensure traceability to the corresponding example or comparative example.

[0138] Step 2: Compressive Strength Test

[0139] According to GB / T50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", a YAW-2000 compression press was used with a maximum load of 2000 kN and a loading rate of 0.5 MPa / s. A uniform load was applied to each sample until failure, and the maximum failure load was recorded. The 28-day compressive strength was calculated in MPa. Three samples from each example or comparative example were tested separately, and the average value was taken as the final result.

[0140] Step 3: Extensibility Test

[0141] According to GB / T50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures", a spread test device was used, with a conical mold height of 300 mm, a top diameter of 100 mm, and a bottom diameter of 200 mm. Ultra-high performance concrete mixture was filled to the top of the mold, the mold was lifted, and the duration was 90 seconds. The average diameter of the horizontal spread of the mixture was measured, in mm. Three samples from each example or comparative example were tested separately, and the average value was taken as the final result.

[0142] Step 4: Surface Quality Inspection

[0143] Under natural light, the surface of each complete curtain wall panel sample was observed using visual inspection tools. The clarity of the decorative pattern (clear or unclear) and surface defects (no peeling, slight peeling, slight corner chipping) were recorded. The inspection results for each sample were recorded independently by two operators, and the results were then combined to form the final result.

[0144] The experimental data are recorded in the table below.

[0145] Sample origin Compressive strength (MPa) Spread (mm) Surface quality Example 1 125.3 548 Clear pattern, no flaking Example 2 128.7 595 Clear pattern, no flaking Example 3 120.1 503 Clear pattern, no flaking Comparative Example 1 108.5 485 Unclear pattern, slight flaking Comparative Example 2 105.2 472 No pattern, slight corner chipping

[0146] The test examples involved compressive strength, swell, and surface quality tests on the exterior wall curtain wall panel samples prepared in Examples 1, 2, 3, Comparative Example 1, and Comparative Example 2. The experimental steps included sample preparation, compressive strength testing, swell testing, and surface quality inspection. The test results showed that the samples from Examples 1, 2, and 3 met the application requirements for exterior wall curtain wall panels in terms of compressive strength, swell, and surface quality, with clear surface decorative patterns and no peeling or corner chipping. The samples from Comparative Example 1 and Comparative Example 2 had lower compressive strength and swell, slight peeling or corner chipping on the surface, and insufficient pattern clarity.

[0147] The test results of Example 1 show that the addition of nano-silica and slow-release antibacterial agents to the ultra-high performance concrete formulation, along with the use of sculpted silicone plates under dynamic temperature-controlled pretreatment and a layered pouring and zoned vibration process, can achieve stable performance. The nano-silica and slow-release antibacterial agents in the formulation fill micropores and enhance early curing performance, thereby improving compressive strength and mixture flowability. After dynamic temperature-controlled pretreatment, the sculpted silicone plates form a micron-level adsorption layer, enhancing interfacial adhesion with the ultra-high performance concrete and reducing surface defects during demolding. Layered pouring and zoned vibration ensure the density of the concrete and the accuracy of the decorative patterns.

[0148] This method significantly improves the toughness of ultra-high performance concrete by optimizing the selection and dosage of synthetic crack-resistant fibers. Five to twenty parts of synthetic crack-resistant fibers with lengths of 6–12 mm and diameters of 0.02–0.2 mm are used. These fibers are uniformly dispersed in the concrete matrix, forming a three-dimensional network support structure. When the concrete is subjected to external forces, the fibers effectively inhibit the initiation and propagation of microcracks, absorb fracture energy, and transform the material from brittle failure to ductile failure. Experimental data show that the ultra-high performance concrete prepared by this method has a splitting tensile strength ≥8 MPa, a flexural strength ≥15 MPa, and a toughness index (at 300 με strain) ≥30 kJ / m², which is far superior to traditional concrete and can meet the deformation adaptability requirements of curtain wall panels during installation and use.

[0149] This method ensures the long-term stability of concrete performance through multi-dimensional control:

[0150] Stable material gradation: Three-stage quartz sand aggregate is used, with continuous and dense gradation and a porosity of ≤15%, avoiding performance fluctuations caused by uneven aggregate distribution;

[0151] Precise control of water-cement ratio: The water-cement ratio is strictly controlled at 0.18~0.22, combined with a polycarboxylate high-performance water-reducing agent with a solid content of 20%~30%, to ensure that the cement hydration is sufficient and uniform, and to reduce drying shrinkage cracks caused by moisture imbalance.

[0152] Segmented curing process: Steam curing is controlled in stages, which slowly increases the strength while reducing internal stress, so that the strength fluctuation of concrete is ≤5% after 28 days and the long-term strength retention rate is ≥90%, and the stability is significantly better than existing technologies.

[0153] This method achieves synergistic improvement through a composite cementitious system and micro-filling:

[0154] Synergistic effect of cementitious materials: 600-850 parts of ordinary Portland cement and 150-200 parts of silica fume form a high-density matrix. The pozzolanic reaction of silica fume can consume Ca(OH)2 produced by cement hydration, generate more CSH gel, and improve the density of the matrix.

[0155] Nano-filler reinforcement: Adding 1 to 5 parts of nano-silica can fill the micropores of cement hydration products and further refine the pore size distribution;

[0156] Fiber reinforcement: The interfacial bond strength between polypropylene fibers and the matrix is ​​≥3MPa, inhibiting the development of macroscopic cracks. Ultimately, this results in a 28-day compressive strength of concrete ≥120MPa, with a maximum of 130MPa, meeting the stringent high-strength requirements of building curtain wall panels.

[0157] The ultra-high performance concrete formulation and preparation process described in this method have good adaptability and can be further extended to the preparation of ultra-high performance concrete for bridges. By adjusting the aggregate gradation and fiber content, the requirements of bridge structures for ultra-high compressive strength, fatigue resistance and durability can be met.

[0158] Although embodiments of the method have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the method, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing ultra-high performance concrete slabs for construction, characterized in that, Includes the following steps: S1. Fix a silicone plate with a thickness of 2-5mm and a hardness of Shore A30-50 to the bottom of a steel or aluminum alloy mold, and carve decorative patterns on the surface with a pattern depth of 0.5-2mm. S2. Using a forced single-shaft concrete mixer, dry mix the cementitious materials, silica fume, titanium dioxide, nano silica, and slow-release antibacterial agent for 1-3 minutes at a speed of 40-60 rpm; add coarse aggregate, medium aggregate, and fine aggregate and mix for 0.5-1.5 minutes; add water, polycarboxylate high-performance water-reducing agent, and defoamer, and mix for 3-5 minutes at a speed of 80-100 rpm; add synthetic crack-resistant fibers and mix for 10-20 minutes at a speed of 60-80 rpm, with a spread of 500-600 mm. By weight: Cementitious materials: 600-850 parts, ordinary Portland cement, strength grade not lower than 42.5; Silica fume: 150–200 parts, average particle size 0.1–0.2 μm; Aggregates: 300-360 parts coarse aggregate, 0.6-1.2 mm quartz sand; 300-360 parts medium aggregate, 0.3-0.6 mm quartz sand; 150-240 parts fine aggregate, 0.1-0.3 mm quartz sand. Synthetic crack-resistant fiber: 5-20 parts, length 6-12 mm; 15-35 parts of polycarboxylate high-performance water-reducing agent, and 0.5-3 parts of defoamer; Titanium dioxide: 5-15 parts; Water: 150-200 parts, water-to-gel ratio 0.18-0.22; 1-5 parts of nano-silica; 0.5–2 parts of sustained-release antibacterial agent; S3. Use a bucket to pour ultra-high performance concrete and vibrate for 20-30 seconds; spray the surface with water retention and cover with plastic film. S4. Curing at 20-25℃ and 90%-95% relative humidity for 20-28 hours until the compressive strength is ≥30MPa, then demolding; steam curing for 6-8 days at 60-75℃ and 90%-95% humidity. In step S1, before fixing the engraving silicone plate, the engraving silicone plate is subjected to dynamic temperature control pretreatment. In the temperature control chamber, the initial temperature is maintained at 28-32℃ for 5-10 minutes, the temperature is increased to 48-52℃ and maintained for 10-15 minutes, and the temperature is decreased to 18-22℃ and maintained for 5-10 minutes. This cycle is repeated 2-3 times, with a total processing time of 30-40 minutes. The temperature control chamber power is 2-5kW, the temperature control accuracy is ±1-2℃, the heating rate is 2-3℃ / min, and the cooling rate is 2-3℃ / min.

2. The method for preparing ultra-high performance concrete slabs for construction according to claim 1, characterized in that, The nano-silica particles have a particle size of 10–50 nm and a specific surface area of ​​200–300 m². 2 / g; Sustained-release antibacterial agents are selected from quaternary ammonium salts, with a sustained-release period of 6 to 12 months.

3. The method for preparing ultra-high performance concrete slabs for construction according to claim 1, characterized in that, The synthetic crack-resistant fiber is a polypropylene fiber with a diameter of 0.02–0.2 mm.

4. The method for preparing ultra-high performance concrete slabs for construction according to claim 1, characterized in that, The titanium dioxide is rutile titanium dioxide with a particle size of 0.2–0.3 μm; the polycarboxylate high-performance water-reducing agent has a solid content of 20%–30% and a water reduction rate of 25%–35%.

5. The method for preparing ultra-high performance concrete slabs for construction according to claim 1, characterized in that, In step S3, layered pouring and zoned vibration are adopted. The first layer of ultra-high performance concrete accounts for 60%–70% of the total thickness and is vibrated for 20–30 seconds at a frequency of 40–60 Hz. The second layer of ultra-high performance concrete accounts for 30%–40% of the total thickness, with a titanium dioxide content of 8–15 parts, and is vibrated for 10–15 seconds at a frequency of 50–70 Hz. The mold is divided into 4–6 vibration zones, with a vibration frequency of 40–60 Hz in the central zone and 50–70 Hz in the edge zone. The vibration equipment power is 3–5 kW, and the area of ​​each zone is 0.5–2 m². 2 .

6. The method for preparing ultra-high performance concrete slabs for construction according to claim 1, characterized in that, In step S1, the pattern area of ​​the engraved silicone plate occupies 30% to 80% of the surface of the silicone plate. It is fixed with bolts or magnetic fixing devices with a spacing of 50 to 100 mm between the fixing devices. The fit deviation between the mold and the silicone plate is ≤0.1 mm.

7. The method for preparing ultra-high performance concrete slabs for construction according to claim 1, characterized in that, In step S4, the steam curing is carried out in stages: the temperature is 58-62℃ for the first 2-3 days and 73-77℃ for the next 3-5 days. The power of the steam curing chamber is 10-20kW, the temperature control accuracy is ±1-2℃, and the humidity is 90%-95%.

8. The method for preparing ultra-high performance concrete slabs for construction according to claim 5, characterized in that, In step S3, the interval between the first and second layers of the layered pouring is 8-12 minutes, and the bucket capacity is 0.3-0.8m³. 3 The pouring speed is 0.5–1.0 m / s. 3 / h; Surface spray water retention capacity: 0.1~0.2L / m 2 The thickness of the plastic film is 0.05 to 0.1 mm.

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