Ultra-high performance concrete for building and preparation method of concrete slab

Abstract

The invention relates to the technical field of building materials, and discloses ultra-high-performance concrete for buildings and a preparation method of a concrete plank. The ultra-high-performance concrete comprises the following components: 600-850 parts of a cementing material; 150 to 200 parts of silica fume; fine aggregate: 300 to 360 parts of coarse aggregate; 5 to 20 parts of synthetic anti-crack fiber; additives: 15-35 parts of a polycarboxylic acid high-performance water reducing agent and 0.5-3 parts of a defoaming agent; 5 to 15 parts of titanium dioxide; and 150 to 200 parts of water. The ultrahigh-performance concrete is prepared from ordinary Portland cement, silica fume, quartz sand aggregate, polypropylene fibers, a polycarboxylic acid high-performance water reducing agent, a defoaming agent, titanium dioxide and water, and nano silicon dioxide and a slow-release antibacterial agent are added, so that the ultrahigh-performance concrete with high toughness, high stability, high adaptability, high compressive strength, high flowability and antibacterial performance is obtained.

Description

TECHNICAL FIELD

[0001] The method relates to the technical field of building materials, in particular to a kind of building super high performance concrete 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, meeting 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, making it difficult to meet the molding requirements of complex decorative patterns, and 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 building super high performance concrete and concrete slab preparation method, solves the problem that the super high performance concrete formula in the prior art lacks optimized components, 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 building super high performance concrete, by mass fraction, includes the following components: Binder: 600-850 parts, ordinary Portland cement is selected, and the strength grade is not less than 42.5 grade; Silica fume: 150-200 parts, average particle size 0.1-0.2 μm; 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; Synthetic anti-cracking fiber: 5-20 parts, length 6-12 mm; 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, water-binder ratio 0.18-0.22.

[0006] According to the technical scheme, the ordinary Portland cement 600-850 parts, silica flour 150-200 parts, quartz sand aggregate, synthetic anti-cracking fiber 5-20 parts, 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, the water-binder ratio is controlled to be 0.18-0.22, the cementing material and the silica flour form a high-strength matrix, the quartz sand aggregate fills the dense structure, and the synthetic anti-cracking fiber improves the tensile property, so that the super high-performance concrete with the compressive strength of more than 120 MPa and the expansion degree of more than 500 mm is obtained, and the super high-performance concrete is suitable for the preparation of the outer wall curtain wall plate.

[0007] Preferably, the additive further comprises nano-silicon dioxide 1-5 parts, the particle size is 10-50 nm, the specific surface area is 200-300 m² / g, and the slow-release antibacterial agent 0.5-2 parts is selected from quaternary ammonium salt, and the slow-release period is 6-12 months.

[0008] According to the technical scheme, the nano-silicon dioxide 1-5 parts with the particle size of 10-50 nm and the slow-release antibacterial agent 0.5-2 parts of quaternary ammonium salt are added in the formula, the nano-silicon dioxide fills the micro-pore and enhances the curing property, and the slow-release antibacterial agent provides the antibacterial function, so that the super high-performance concrete with the compressive strength of more than 125 MPa and the long-term antibacterial property is obtained.

[0009] Preferably, the synthetic anti-cracking fiber is polypropylene fiber with the diameter of 0.02-0.2 mm.

[0010] According to the technical scheme, the polypropylene fiber with the length of 6-12 mm and the diameter of 0.02-0.2 mm is selected as the synthetic anti-cracking fiber, the fiber is uniformly dispersed in the matrix, and the tensile strength is enhanced, so that the super high-performance concrete with the reduced crack occurrence is obtained, and the super high-performance concrete is suitable for the outer wall curtain wall plate.

[0011] Preferably, the titanium dioxide is rutile titanium dioxide with the particle size of 0.2-0.3 μm, and the polycarboxylic acid high-performance water reducing agent has the solid content of 20%-30% and the water-reducing rate of 25%-35%.

[0012] According to the technical scheme, the rutile titanium dioxide with the particle size of 0.2-0.3 μm and the polycarboxylic acid high-performance water reducing agent with the solid content of 20%-30% are used, the rutile titanium dioxide improves the surface whiteness, and the water reducing agent optimizes the flowability of the mixture, so that the super high-performance concrete with the expansion degree of more than 550 mm and the high surface whiteness is obtained, and the super high-performance concrete is suitable for the complex pattern forming.

[0013] A preparation method of a super high-performance concrete plate for building comprises the following steps: S1, fix the engraved silicone plate at the bottom of the steel or aluminum alloy mold, thickness 2-5 mm, hardness Shore A 30-50, surface engraved decorative pattern, pattern depth 0.5-2 mm; S2, use a forced single-axis concrete mixer to dry mix cementitious materials, silica fume, titanium dioxide and admixtures for 1-3 minutes at a speed of 40-60 rpm; add fine aggregate and stir for 0.5-1.5 minutes; add water and polycarboxylic acid high-performance water reducing agent, defoaming agent, and stir for 3-5 minutes at a speed of 80-100 rpm; add synthetic anti-cracking fibers and stir for 10-20 minutes at a speed of 60-80 rpm with an extension of 500-600 mm; S3, use a bucket to pour the ultra-high performance concrete and vibrate for 20-30 seconds; spray water on the surface and cover it with plastic film; S4, cure at a temperature of 20-25°C and a relative humidity of 90%-95% for 20-28 hours, with a compressive strength of ≥30 MPa; steam curing for 6-8 days at a temperature of 60-75°C and a humidity of 90%-95%.

[0014] Through the above technical solution, since the engraved silicone plate is fixed at the bottom of the mold with a thickness of 2-5 mm, a hardness of Shore A 30-50, and a surface engraved pattern with a depth of 0.5-2 mm, the ultra-high performance concrete is prepared by forced stirring with an extension of 500-600 mm, poured into a bucket and vibrated for 20-30 seconds, the surface is sprayed with water and covered with plastic film, and cured for 20-28 hours with a compressive strength of 30 MPa before demolding, and steam cured for 6-8 days at a temperature of 60-75°C, the engraved silicone plate forms a precise pattern template, the stirring ensures uniform mixing, and the pouring and curing promote strength, thus obtaining a curtain wall panel with clear surface patterns and no peeling defects, with a compressive strength of not less than 120 MPa.

[0015] Preferably, in step S1, before fixing the engraved silicone plate, the engraved silicone plate is subjected to dynamic temperature control pretreatment, which is kept at an initial temperature of 28-32°C for 5-10 minutes, raised to 48-52°C for 10-15 minutes, and then lowered to 18-22°C for 5-10 minutes, with a cycle of 2-3 times, a total processing time of 30-40 minutes, a temperature control box power of 2-5 kW, a temperature control accuracy of ±1-2°C, a temperature rise rate of 2-3°C / min, and a temperature drop rate of 2-3°C / min.

[0016] Through the above technical solution, since the engraved silicone plate is subjected to dynamic temperature control pretreatment, the temperature control box power is 2-5 kW, the temperature control accuracy is ±1-2°C, the temperature is kept at 28-32°C for 5-10 minutes, 48-52°C for 10-15 minutes, and 18-22°C for 5-10 minutes, with a cycle of 2-3 times, a pretreatment microscale adsorption layer is formed, and the interface adhesion with the concrete is enhanced, thus obtaining a curtain wall panel with clearer surface patterns and fewer demolding defects.

[0017] Preferably, in step S3, layered pouring and partitioned vibrating are adopted, the thickness of the first layer of ultra-high performance concrete accounts for 60-70% of the total thickness, vibrating is performed for 20-30 seconds at a frequency of 40-60 Hz; the thickness of the second layer of ultra-high performance concrete accounts for 30-40% of the total thickness, the content of titanium dioxide is 8-15 parts, vibrating is performed for 10-15 seconds at a frequency of 50-70 Hz; the mold is divided into 4-6 vibrating areas, the center area is vibrated at a frequency of 40-60 Hz, the edge area is vibrated at a frequency of 50-70 Hz, the power of the vibrating equipment is 3-5 kW, and the area of each area is 0.5-2 m².

[0018] Through the above technical solution, since layered pouring is adopted, the thickness of the first layer accounts for 60-70%, vibrating is performed for 20-30 seconds at a frequency of 40-60 Hz, the thickness of the second layer accounts for 30-40%, vibrating is performed for 10-15 seconds at a frequency of 50-70 Hz, the mold is divided into 4-6 vibrating areas, the center frequency is 40-60 Hz, the edge frequency is 50-70 Hz, layered pouring ensures uniform material distribution, and partitioned vibrating improves the consistency of compactness, therefore, a curtain wall plate with high pattern accuracy and uniform surface is obtained.

[0019] Preferably, in step S1, the pattern area of the engraved silica gel plate accounts for 30-80% of the surface of the silica gel plate, a bolt or a magnetic attraction fixing device is used for fixing, the spacing between the fixing devices is 50-100 mm, and the deviation of the mold and the silica gel plate in lamination is ≤0.1 mm.

[0020] Through the above technical solution, since the pattern area of the engraved silica gel plate accounts for 30-80% of the surface, a bolt or a magnetic attraction fixing device is used, the spacing is 50-100 mm, and the lamination deviation is ≤0.1 mm, the fixing device ensures that the silica gel plate is closely laminated with the mold, and the pattern template provides accurate molding, therefore, a curtain wall plate with high pattern molding accuracy and no deviation is obtained.

[0021] Preferably, in step S4, steam curing is performed in stages, the temperature is 58-62℃ for the first 2-3 days, the temperature is 73-77℃ for the last 3-5 days, the power of the steam curing box is 10-20 kW, the temperature control accuracy is ±1-2℃, and the humidity is 90-95%.

[0022] Through the above technical solution, since steam curing is performed in stages, the temperature is 58-62℃ for the first 2-3 days, the temperature is 73-77℃ for the last 3-5 days, the power of the curing box is 10-20 kW, the temperature control accuracy is ±1-2℃, staged curing optimizes the development of strength, and stabilizes the curing environment, therefore, a curtain wall plate with a compressive strength of 120 MPa or more and a stable surface is obtained.

[0023] Preferably, in step S3, the first layer and the second layer of the layered pouring are poured at intervals of 8-12 minutes, the bucket capacity is 0.3-0.8 m³, the pouring speed is 0.5-1.0 m³ / h, the surface spraying water retention is 0.1-0.2 L / m², and the plastic film thickness is 0.05-0.1 mm.

[0024] Through the above technical solution, since the layered pouring is at intervals of 8-12 minutes, the bucket capacity is 0.3-0.8 m³, the pouring speed is 0.5-1.0 m³ / h, the surface spraying water retention is 0.1-0.2 L / m², and the plastic film thickness is 0.05-0.1 mm, the interval controls the interlayer bonding, the spraying water retention maintains the surface humidity, and therefore, the curtain wall panel with tight interlayer bonding and no surface cracks is obtained.

[0025] The method provides a kind of super high performance concrete and concrete slab preparation method for building.There are following beneficial effects: 1, the method is prepared by using ordinary portland cement, silica fume, quartz sand aggregate, polypropylene fiber, polycarboxylate 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, cementitious material and silica fume form high-strength matrix, quartz sand aggregate ensures dense structure, polypropylene fiber enhances tensile property, water reducing agent and defoaming agent optimize fluidity, nano silicon dioxide fills micro-pore, slow-release antibacterial agent provides antibacterial function, and therefore, high compressive strength, high fluidity and antibacterial performance of super high performance concrete are obtained.

[0026] The method is fixed to the bottom of the mold by using engraved silica gel plate, the surface is engraved with decorative pattern, combined with dynamic temperature control pretreatment, the pretreatment is formed micron level adsorption layer by circulating temperature rise in temperature control box, the interface adhesion with super high performance concrete is enhanced, and the fixing device ensures that the silica gel plate is closely attached to the mold, and therefore, the curtain wall panel with clear surface decorative pattern, no peeling or corner dropping is obtained, and the demolding defect problem in the prior art is solved.

[0027] The method is poured by layering, the first layer and the second layer are poured with different thicknesses respectively, the second layer increases the titanium dioxide content, and different frequencies are used for partitioning and vibrating different regions, the layered pouring ensures uniform material distribution, the partitioning and vibrating improves the consistency of the density, and the titanium dioxide improves the surface whiteness and gloss, and therefore, the curtain wall panel with high decorative pattern forming precision and uniform surface quality is obtained.

[0028] The method is prepared by forced mixing to prepare super high performance concrete, the spread is controlled, the bucket is poured and the pouring interval is controlled, the surface is sprayed with water and covered with plastic film, the mixing ensures the uniformity of the mixture, the pouring interval and the water retention measures optimize the interlayer bonding and the surface humidity, and therefore, the curtain wall panel with tight interlayer bonding and no surface cracks is obtained. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 A method flow chart of the method of preparing a building super high performance concrete and a concrete slab. DETAILED DESCRIPTION

[0030] The application is further described in detail below in conjunction with the accompanying Figure 1 and examples.

[0031] Ultra-high performance concrete (UHPC) is widely used in the field of building exterior wall and curtain wall slabs due to its excellent mechanical properties and durability. However, there is a major drawback in the prior art in preparing UHPC exterior wall and curtain wall slabs: it is difficult for traditional UHPC formulations to simultaneously achieve high compressive strength, high fluidity and antibacterial performance, resulting in limited performance of the curtain wall slabs 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 takes into account strength, fluidity and functionality, making it difficult to meet the comprehensive requirements of exterior wall and curtain wall slabs in terms of mechanical properties, construction performance and surface antibacterial requirements.

[0032] Based on this finding, the applicant has optimized the formulation and process through experiments, initially by adjusting the proportions of ordinary Portland cement, silica fume and admixtures to select a formulation that takes into account strength and fluidity; then introducing nano-silicon dioxide and slow-release antibacterial agents to verify their functional improvement; finally, through engraving silica gel plates and layered pouring experiments, the surface quality of the curtain wall slabs is optimized. The technical solution is based on the above research results.

[0033] Sources of raw materials, reagents, methods and equipment To ensure that those skilled in the art can implement the method, the sources of raw materials, reagents, methods and equipment used in the following examples are specified. All raw materials, reagents and equipment are commercially available or can be obtained through conventional processing, meeting industrial application standards.

[0034] Raw materials and reagents Ordinary Portland cement: strength grade 42.5, in accordance with GB175-2007 standard.

[0035] Silica fume: average particle size 0.1~0.2μm, specific surface area 200~300m² / g.

[0036] Quartz sand: coarse aggregate: particle size 0.6~1.2mm; medium aggregate: particle size 0.3~0.6mm; fine aggregate: particle size 0.1~0.3mm.

[0037] Synthetic crack-resistant fibers: polypropylene fibers, length 6~12mm, diameter 0.02~0.2mm.

[0038] Admixtures: polycarboxylic acid high-performance water reducing agent: solid content 20%~30%, water reducing rate 25%~35%.

[0039] Defoamer: Non-ionic.

[0040] Nano-silica: Particle size 10-50 nm, specific surface area 200-300 m² / g.

[0041] Slow-release antibacterial agent: Quaternary ammonium salt, slow-release period 6-12 months.

[0042] Titanium dioxide: Rutile type, particle size 0.2-0.3 μm.

[0043] Water: Clean water meeting GB 5749-2006 standards.

[0044] Carved silicone plate: Thickness 2-5 mm, hardness Shore A 30-50, surface carved with decorative patterns.

[0045] Release agent: Conventional concrete release agent.

[0046] Forced single-axis concrete mixer: Capacity 0.5-1.0 m³, power 15-30 kW.

[0047] Temperature control box: Power 2-5 kW, temperature control accuracy ±1-2°C, used for dynamic temperature control pretreatment of carved silicone plate.

[0048] Hanging bucket: Capacity 0.3-0.8 m³, equipped with flow control device.

[0049] High-frequency vibration equipment: Power 3-5 kW, frequency 40-70 Hz.

[0050] Steam curing box: Power 10-20 kW, temperature control accuracy ±1-2°C, humidity 90%-95%.

[0051] Steel or aluminum alloy mold: Size 1×1 m to 4×2 m, inner surface polished, surface roughness Ra≤0.8 μm.

[0052] Test method: Compressive strength test: According to GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete", using 150×150×150 mm samples.

[0053] Slump test: According to GB / T 50080-2016 "Standard for Test Methods of Properties of Fresh Concrete", duration 90 seconds.

[0054] Surface quality inspection: Visual observation of curtain wall plate surface, recording pattern clarity and peeling / corner dropping.

[0055] Process steps: All steps use conventional concrete preparation process, equipment operation conforms to industry standards.

[0056] The above raw materials, reagents and equipment can be purchased or obtained by conventional processing, and the test method is a known technology in the art, ensuring full disclosure of the present method.

[0057] Example 1 Raw materials: the formulation of ultra-high performance concrete is as follows in mass fraction: ordinary Portland cement 700 parts, strength grade 42.5 grade, in line with GB175-2007 standard; Silica fume 180 parts, average particle size 0.15 μm, specific surface area 250 m² / g; Coarse aggregate 330 parts, quartz sand, particle size 0.6-1.2 mm; Medium aggregate 330 parts, quartz sand, particle size 0.3-0.6 mm; Fine aggregate 200 parts, quartz sand, particle size 0.1-0.3 mm; Synthetic anti-cracking fiber 10 parts, polypropylene fiber, length 9 mm, diameter 0.1 mm; Polycarboxylic acid high-performance water reducing agent 25 parts, solid content 25%, water reducing rate 30%; Defoaming agent 1.5 parts, non-ionic; Nano-silicon dioxide 3 parts, particle size 30 nm, specific surface area 250 m² / g; Slow-release antibacterial agent 1 part, quaternary ammonium salt, slow-release period 9 months; Titanium dioxide 10 parts, rutile type, particle size 0.25 μm; Water 180 parts, in line with GB5749-2006 standard, water-binder ratio 0.20.

[0058] Steps: S1, mold preparation and dynamic temperature control pretreatment: select 4x2m steel mold, polish the inner surface, surface roughness Ra≤0.8 μm, uniformly spray release agent, coating thickness 0.05 mm. Fix the engraved silicone plate, thickness 3 mm, hardness Shore A 40, surface engraved stone pattern decoration pattern, pattern depth 1 mm, pattern area accounts for 50% of the surface of the silicone plate. Dynamic temperature control pretreatment is carried out in a temperature control box with a power of 3 kW and a temperature control accuracy of ±1℃. The initial temperature is kept at 30℃ for 8 minutes, then raised to 50℃ at a rate of 2.5℃ / min and kept for 12 minutes, then cooled to 20℃ at a rate of 2.5℃ / min and kept for 8 minutes, and the cycle is repeated twice for a total processing time of 36 minutes. Use a bolt fixing device with a spacing of 80 mm to fix the engraved silicone plate, and the fitting deviation is ≤0.1 mm.

[0059] S2, Ultra-high performance concrete preparation: A compulsory single-axis concrete mixer with a capacity of 0.8 m³ and a power of 20 kW was used. The ordinary Portland cement, silica fume, titanium dioxide, nano-silicon dioxide, and slow-release antibacterial agent were dry-mixed for 2 minutes at a speed of 50 rpm. Coarse aggregate, medium aggregate, and fine aggregate were added and stirred for 1 minute at a speed of 50 rpm. Water, polycarboxylic acid high-performance water reducer, and defoaming agent were slowly added over a period of 1.5 minutes, and the mixture was stirred for 4 minutes at a speed of 90 rpm. Synthetic anti-cracking fibers were added in four batches, with an interval of 45 seconds between each batch, and the mixture was stirred for 15 minutes at a speed of 70 rpm. The spread was tested according to GB / T50080-2016, with a duration of 90 seconds and a spread of 550 mm.

[0060] S3, Layered pouring and zoned vibration: A bucket with a capacity of 0.5 m³ and a pouring speed of 0.8 m³ / h was used. The first layer of ultra-high performance concrete was poured to a thickness of 13 mm, accounting for 65% of the total thickness of 20 mm, and was vibrated for 25 seconds at a frequency of 50 Hz using a high-frequency vibration device with a power of 4 kW. The second layer of ultra-high performance concrete was poured to a thickness of 7 mm, accounting for 35% of the total thickness, and the titanium dioxide content was 12 parts. The mixture was vibrated for 12 seconds at a frequency of 60 Hz. The mold was divided into four vibration zones, each with an area of 1 m². The center zone was vibrated at a frequency of 50 Hz, and the edge zone was vibrated at a frequency of 60 Hz. The first and second layers were poured with an interval of 10 minutes. The surface was sprayed with water at a rate of 0.15 L / m², and a plastic film with a thickness of 0.08 mm was applied.

[0061] S4, Curing and demolding: The panel was placed in a steam curing box with a power of 15 kW and a temperature control accuracy of ±1.5℃ and a humidity of 92% for 24 hours at a temperature of 22℃ and a relative humidity of 92%. The compressive strength was tested according to GB / T50081-2019, reaching 32 MPa. The panel was lifted using a mechanical lifting device at a speed of 0.15 m / min and was demolded. After demolding, the panel was placed in a steam curing box with a power of 15 kW and a temperature control accuracy of ±1.5℃ and a humidity of 92% for 7 days. The temperature was 60℃ for the first 3 days and 75℃ for the last 4 days.

[0062] Results: The exterior wall panel was obtained with a clear stone-like pattern on the surface without peeling or corner dropping.

[0063] Example 2 Raw materials: The ultra-high performance concrete formulation is as follows in mass parts: ordinary Portland cement 850 parts, strength grade 42.5, meeting GB175-2007 standard; Silica fume 200 parts, average particle size 0.2 μm, specific surface area 300 m² / g; Coarse aggregate 360 parts, quartz sand, particle size 0.6-1.2 mm; Medium aggregate 360 parts, quartz sand, particle size 0.3-0.6 mm; Fine aggregate 240 parts, quartz sand, particle size 0.1-0.3 mm; Synthetic anti-cracking fiber 20 parts, polypropylene fiber, length 12 mm, diameter 0.2 mm; Polycarboxylic acid high-performance water-reducing agent 35 parts, solid content 30%, water-reducing rate 35%; Defoaming agent 3 parts, non-ionic; Nano-silicon dioxide 5 parts, particle size 50 nm, specific surface area 300 m² / g; Slow-release antibacterial agent 2 parts, quaternary ammonium salt, slow-release period 12 months; Titanium dioxide 15 parts, rutile type, particle size 0.3 μm Water 200 parts, in line with GB5749-2006 standard, water-binder ratio 0.18.

[0064] Step: S1, mold preparation and dynamic temperature control pretreatment: select 3x1.5m aluminum alloy mold, inner surface polishing treatment, surface roughness Ra≤0.8μm, spray release agent, coating thickness 0.08mm. Fix the engraved silicone plate, thickness 5mm, hardness Shore A 50, surface engraved geometric texture pattern, pattern depth 2mm, pattern area accounts for 80% of the surface of the silicone plate. Dynamic temperature control pretreatment is carried out in the temperature control box, power 5kW, temperature control accuracy ±1℃, initial temperature 32℃ for 5 minutes, heated to 52℃, heating rate 3℃ / min, keep for 10 minutes, cooled to 22℃, cooling rate 3℃ / min, keep for 5 minutes, cycle 3 times, total processing time 40 minutes. Use magnetic fixing device, spacing 50mm, fix the engraved silicone plate, sticking deviation ≤0.1mm.

[0065] S2, preparation of ultra-high performance concrete: use forced single-couch concrete mixer, capacity 1.0m³, power 30kW. Dry mix ordinary portland cement, silica fume, titanium dioxide, nano-silicon dioxide, slow-release antibacterial agent for 3 minutes, speed 40rpm; add coarse aggregate, medium aggregate, fine aggregate, stir for 1.5 minutes, speed 40rpm; slowly add water, polycarboxylic acid high-performance water-reducing agent, defoaming agent, feeding time 2 minutes, stir for 5 minutes, speed 80rpm; add synthetic anti-cracking fiber in 5 batches, each batch interval 60 seconds, stir for 20 minutes, speed 60rpm. Test the spread, duration 90 seconds, spread 600mm.

[0066] S3, Layered pouring and partitioned vibrating: use a bucket, capacity 0.8 m³, pouring speed 1.0 m³ / h. The first layer of ultra-high performance concrete is poured to 18 mm, accounting for 70% of the total thickness, total thickness 25 mm, vibrated for 30 seconds, frequency 60 Hz, high-frequency vibrating equipment is used, power 5 kW. The second layer of ultra-high performance concrete is poured to 7 mm, accounting for 30% of the total thickness, titanium dioxide content 15 parts, vibrated for 15 seconds, frequency 70 Hz. The mold is divided into 6 vibrating areas, each area 0.75 m², the center area vibrates at a frequency of 60 Hz, and the edge area vibrates at a frequency of 70 Hz. The first layer and the second layer are poured 8 minutes apart. Spray 0.2 L / m² of water on the surface, cover with plastic film, thickness 0.1 mm.

[0067] S4, Curing and demolding: under the condition of temperature 20℃, relative humidity 95%, static curing for 28 hours, the compressive strength reaches 35 MPa, and demolding. After demolding, the curtain wall plate is placed in a steam curing box, power 20 kW, temperature control accuracy ±1℃, humidity 95%, curing for 8 days, the first 3 days at a temperature of 58℃, and the last 5 days at a temperature of 73℃.

[0068] Results: The outer wall curtain wall plate is obtained, the surface geometric texture pattern is clear, and there is no peeling or corner dropping.

[0069] Example 3 Raw materials: the formula of ultra-high performance concrete is as follows in mass parts: ordinary Portland cement 600 parts, strength grade 42.5 grade, in line with GB175-2007 standard; Silica fume 150 parts, average particle size 0.1 μm, specific surface area 200 m² / g; Coarse aggregate 300 parts, quartz sand, particle size 0.6-1.2 mm; Medium aggregate 300 parts, quartz sand, particle size 0.3-0.6 mm; Fine aggregate 150 parts, quartz sand, particle size 0.1-0.3 mm; Synthetic anti-cracking fiber 5 parts, polypropylene fiber, length 6 mm, diameter 0.02 mm; Polycarboxylic acid high-performance water reducing agent 15 parts, solid content 20%, water reducing rate 25%; Defoaming agent 0.5 parts, non-ionic; Nano-silicon dioxide 1 part, particle size 10 nm, specific surface area 200 m² / g; Slow-release antibacterial agent 0.5 parts, quaternary ammonium salt, slow-release period 6 months; Titanium dioxide 5 parts, rutile type, particle size 0.2 μm; Water 150 parts, in line with GB5749-2006 standard, water-binder ratio 0.22.

[0070] Step: S1, mold preparation and dynamic temperature control pretreatment: select 2x1 m steel mold, inner surface polishing treatment, surface roughness Ra≤0.8 μm, spray release agent, coating thickness 0.06 mm. Fix the engraved silica gel plate, thickness 2 mm, hardness Shore A 30, surface engraved wood grain decorative pattern, pattern depth 0.5 mm, pattern area accounts for 30% of the surface of the silica gel plate. Dynamic temperature control pretreatment is carried out in the temperature control box, power 2 kW, temperature control accuracy ±2℃, initial temperature 28℃ for 10 minutes, temperature rise to 48℃, temperature rise rate 2℃ / min, keep for 15 minutes, temperature drop to 18℃, temperature drop rate 2℃ / min, keep for 10 minutes, cycle 2 times, total processing time 38 minutes. Use bolt fixing device, spacing 100 mm, fix the engraved silica gel plate, fit deviation ≤0.1 mm.

[0071] S2, preparation of ultra-high performance concrete: use forced single-couch concrete mixer, capacity 0.5 m³, power 15 kW. Dry mix ordinary portland cement, silica fume, titanium dioxide, nano silicon dioxide, slow-release antibacterial agent for 1 minute, speed 60 rpm; add coarse aggregate, medium aggregate, fine aggregate, stir for 0.5 minutes, speed 60 rpm; slowly add water, polycarboxylic acid high-performance water reducing agent, defoaming agent, feeding time 1 minute, stir for 3 minutes, speed 100 rpm; add synthetic anti-cracking fiber in 3 batches, each batch interval 30 seconds, stir for 10 minutes, speed 80 rpm. Test the spread, duration 90 seconds, spread 500 mm.

[0072] S3, layered pouring and partitioned vibrating: use a bucket, capacity 0.3 m³, pouring speed 0.5 m³ / h. Pour the first layer of ultra-high performance concrete to 9 mm, accounting for 60% of the total thickness, total thickness 15 mm, vibrate for 20 seconds, frequency 40 Hz, use high-frequency vibrating equipment, power 3 kW. Pour the second layer of ultra-high performance concrete to 6 mm, accounting for 40% of the total thickness, titanium dioxide content 8 parts, vibrate for 10 seconds, frequency 50 Hz. The mold is divided into 4 vibrating areas, each area 0.5 m², center area vibrating frequency 40 Hz, edge area vibrating frequency 50 Hz. The first layer and the second layer are poured with an interval of 12 minutes. Spray water retention 0.1 L / m² on the surface, cover with plastic film, thickness 0.05 mm.

[0073] S4, curing and demolding: under the condition of temperature 25℃, relative humidity 90%, static curing for 20 hours, detect the compressive strength to reach 30 MPa, and demold. After demolding, the curtain wall plate is placed in a steam curing box, power 10 kW, temperature control accuracy ±2℃, humidity 90%, curing for 6 days, temperature 62℃ for the first 2 days, and temperature 77℃ for the last 4 days.

[0074] Results: the outer wall curtain wall plate with clear wood grain pattern is obtained without peeling or corner dropping.

[0075] Comparative Example 1 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, ordinary silicone plates are used instead of carved silicone plates in step S1, and dynamic temperature control pretreatment is not performed, single pouring is used instead of layered pouring and partitioned vibration in step S3, the mold is not vibrated in different zones, the vibration time is 20 seconds, and the frequency is 50 Hz. The rest are the same.

[0076] Result: The exterior curtain wall panels were obtained, but the surface pattern was not clear enough and there was slight peeling.

[0077] Comparative Example 2 Compared with Example 2, the differences are as follows: the ultra-high performance concrete formula does not contain nano-silica and slow-release antibacterial agent, an ordinary steel mold is used instead of the engraved silicone plate in step S1, and no dynamic temperature control pretreatment is performed, a single pouring is used instead of layered pouring and partitioned vibration in step S3, the mold is not vibrated in different zones, the vibration time is 25 seconds, and the frequency is 60 Hz. The rest are the same.

[0078] Result: The exterior curtain wall panels were obtained, with no pattern on the surface and slight corner chipping.

[0079] Test example: This experiment tested the performance of exterior curtain wall panel samples prepared in Examples 1, 2, 3, Comparative Examples 1, and 2. Test items included compressive strength, expansion, and surface quality. The testing equipment included a press, an expansion tester, and a visual inspection tool. The testing environment was a temperature of 20-25°C and a relative humidity of 90%-95%. The following are the experimental steps: Step 1: Sample preparation Three exterior curtain wall panel samples (150 × 150 × 150 mm) were collected from each of Example 1, Example 2, Example 3, Comparative Example 1, and Comparative Example 2 for compressive strength testing. Three additional samples of the ultra-high performance concrete mixture were collected for expansion testing. Intact curtain wall panel samples were retained for surface quality inspection. Each sample was numbered to ensure traceability to the corresponding Example or Comparative Example.

[0080] Step 2: Compressive strength test According to GB / T50081-2019, "Standard for Test Methods of Physical and Mechanical Properties of Concrete," a press model YAW-2000 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. The maximum failure load was recorded, and the 28-day compressive strength was calculated in MPa. Three samples were tested for each Example or Comparative Example, and the average value was taken as the final result.

[0081] Step 3: Scalability test According to GB / T 50080-2016 Standard for Testing Long-term Performance of Ordinary Concrete, the spread test device was used, the height of the cone-shaped mold was 300 mm, the top diameter was 100 mm, and the bottom diameter was 200 mm. The ultra-high performance concrete mixture was filled to the top of the mold, the mold was lifted, the duration was 90 seconds, the average diameter of the horizontal spread of the mixture was measured, and the unit was mm. Three samples of each example or comparative example were tested respectively, and the average value was taken as the final result.

[0082] Step 4: Surface quality inspection Under natural light, the surface of each complete curtain wall panel sample was observed using visual inspection tools, and the clarity of the decorative pattern (clear or unclear) and surface defects (no peeling, slight peeling, slight corner dropping) were recorded. The inspection results of each sample were recorded by two operators independently, and the final results were unified.

[0083] The experimental data are recorded in the following table.

[0084] 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 Test Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2 were tested for compressive strength, spread and surface quality. The experimental steps included sample preparation, compressive strength test, spread test and surface quality inspection. The test results showed that the samples of Example 1, Example 2 and Example 3 met the application requirements of the outer wall curtain wall panel in terms of compressive strength, spread and surface quality, and the surface decorative pattern was clear, without peeling or corner dropping phenomenon; the samples of Comparative Example 1 and Comparative Example 2 had low compressive strength and spread, and there was slight peeling or corner dropping on the surface, and the pattern clarity was insufficient.

[0085] The test results of Example 1 showed that the addition of nano-silicon dioxide and slow-release antibacterial agent in the ultra-high performance concrete formula, the use of engraved silica gel plate pretreated by dynamic temperature control, and the preparation process of layered pouring and partitioned vibration could realize stable performance. The role of nano-silicon dioxide and slow-release antibacterial agent in the formula is to fill the micro-pores and enhance the early curing performance, thereby improving the compressive strength and the flowability of the mixture. After the engraved silica gel plate is pretreated by dynamic temperature control, a micron-sized adsorption layer is formed, which enhances the interfacial adhesion with the ultra-high performance concrete and reduces the surface defects during demolding. Layered pouring and partitioned vibration ensure the compactness of the concrete and the forming precision of the decorative pattern.

[0086] The method significantly improves the toughness of ultra-high performance concrete by optimizing the selection and dosage of synthetic anti-cracking fibers. The synthetic anti-cracking fibers with a length of 6-12 mm and a diameter of 0.02-0.2 mm are selected in an amount of 5-20 parts. The synthetic anti-cracking fibers are uniformly dispersed in the concrete matrix to form a three-dimensional network support structure. When the concrete is subjected to external forces, the fibers can effectively inhibit the initiation and propagation of micro-cracks, absorb fracture energy, and change the material from brittle failure to ductile failure. Experimental data show that the split tensile strength of the ultra-high performance concrete prepared by the method is ≥8 MPa, the flexural strength is ≥15 MPa, and the toughness index (at a strain of 300 με) is ≥30 kJ / m², which is much better than traditional concrete and can meet the requirements of curtain wall panels for deformation adaptability during installation and use.

[0087] The method ensures the long-term stability of concrete performance through multi-dimensional control: Material gradation stability: three-stage quartz sand aggregate is used, with continuous and dense gradation, and void ratio ≤15%, to avoid performance fluctuations caused by uneven aggregate distribution; Precise control of water-binder ratio: the water-binder ratio is strictly controlled at 0.18-0.22, combined with a polycarboxylate high-performance water reducer with a solid content of 20%-30%, to ensure full and uniform cement hydration and reduce dry shrinkage cracks caused by water imbalance; Segmented curing process: steam curing is controlled in stages to slowly increase strength while reducing internal stress, resulting in a 28-day strength fluctuation of the concrete ≤5%, a long-term use strength retention rate ≥90%, and significantly better stability than existing technologies.

[0088] The method improves through the synergy of composite cementitious system and micro-filling: Cementitious material synergy: 600-850 parts of ordinary Portland cement and 150-200 parts of silica fume form a high-density matrix, and the pozzolanic reaction of silica fume can consume Ca(OH)2 generated during cement hydration to generate more C-S-H gel, improving the matrix density; Nano-filling enhancement: adding 1-5 parts of nano-silicon dioxide can fill the micro-pores of cement hydration products, further refining the pore size distribution; Fiber reinforcement: the interfacial adhesion between polypropylene fibers and the matrix is ≥3 MPa, which can inhibit the development of macroscopic cracks. Finally, the 28-day compressive strength of the concrete is ≥120 MPa, and the highest can reach 130 MPa, meeting the stringent requirements of architectural curtain wall panels for high strength.

[0089] The ultra-high performance concrete formula and preparation process of the method have good adaptability and can be further extended to the preparation of bridge ultra-high performance concrete. By adjusting the aggregate gradation and fiber dosage, the requirements of bridge structure for ultra-high compressive strength, fatigue resistance, and durability can be met.

[0090] While embodiments of the method have been shown and described, it is to be understood that the embodiments can be varied, modified, substituted and otherwise changed by those skilled in the art without departing from the principles and spirit of the method, the scope of which is to be determined by the following claims and their equivalents.

Claims

1. An ultra-high performance concrete for construction, characterized in that: Calculated by mass, it includes the following components: Cementitious material: 600-850 parts, ordinary Portland cement, strength grade not less than 42.5; Silica fume: 150-200 parts, average particle size 0.1-0.2 μm; Aggregate: 300-360 parts of coarse aggregate, quartz sand with a particle size of 0.6-1.2 mm; 300-360 parts of medium aggregate, quartz sand with a particle size of 0.3-0.6 mm; 150-240 parts of fine aggregate, quartz sand with a particle size of 0.1-0.3 mm; Synthetic crack-resistant fiber: 5-20 parts, length 6-12mm; Admixture: 15-35 parts of polycarboxylic acid high-performance water reducer, 0.5-3 parts of defoaming agent; Titanium dioxide: 5-15 parts; Water: 150-200 parts, water-to-binder ratio 0.18-0.

22.

2. The ultra-high performance concrete for construction according to claim 1, characterized in that: The admixture further comprises 1 to 5 parts of nano silicon dioxide with a particle size of 10 to 50 nm and a specific surface area of ​​200 to 300 m² / g; and 0.5 to 2 parts of a sustained-release antibacterial agent, which is a quaternary ammonium salt with a sustained-release period of 6 to 12 months.

3. The ultra-high performance concrete for construction according to claim 1, characterized in that: The synthetic anti-cracking fiber is polypropylene fiber with a diameter of 0.02 to 0.2 mm.

4. The ultra-high performance concrete 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 polycarboxylic acid high-performance water reducer has a solid content of 20%-30% and a water reduction rate of 25%-35%.

5. A method for preparing ultra-high performance concrete slabs for construction, characterized in that: The ultra-high performance concrete for construction according to any one of claims 1 to 4 comprises the following steps: S1. Fix a carved silicone plate at the bottom of a steel or aluminum alloy mold with a thickness of 2 to 5 mm and a hardness of Shore A 30 to 50. Carve a decorative pattern on the surface with a depth of 0.5 to 2 mm. S2. Use a mandatory single-horizontal-shaft concrete mixer to dry mix the cementitious material, silica fume, titanium dioxide, and admixtures for 1 to 3 minutes at a speed of 40 to 60 rpm; add fine aggregate and mix for 0.5 to 1.5 minutes; add water and polycarboxylic acid high-performance water reducer and defoamer and mix for 3 to 5 minutes at a speed of 80 to 100 rpm; add synthetic anti-cracking fiber and mix for 10 to 20 minutes at a speed of 60 to 80 rpm, with a spread of 500 to 600 mm; S3. Use a bucket to pour ultra-high performance concrete and vibrate for 20 to 30 seconds; spray the surface with water to retain moisture and cover with plastic film; S4. Curing for 20 to 28 hours at a temperature of 20 to 25°C and a relative humidity of 90% to 95%. Demoulding is carried out after the compressive strength reaches ≥30 MPa. Steam curing is carried out for 6 to 8 days at a temperature of 60 to 75°C and a relative humidity of 90% to 95%.

6. The method for preparing ultra-high performance concrete slab for construction according to claim 5, characterized in that: In step S1, before fixing the engraved silicone plate, the engraved silicone plate is subjected to dynamic temperature control pretreatment. In the temperature control box, the initial temperature is maintained at 28~32°C for 5~10 minutes, the temperature is increased to 48~52°C and maintained for 10~15 minutes, and the temperature is reduced to 18~22°C and maintained for 5~10 minutes. This cycle is repeated 2~3 times, with a total treatment time of 30~40 minutes. The temperature control box has a power of 2~5kW, a temperature control accuracy of ±1~2°C, a heating rate of 2~3°C / min, and a cooling rate of 2~3°C / min.

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

8. The method for preparing ultra-high performance concrete slab for construction according to claim 5, 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, and is fixed using bolts or magnetic fixing devices, with a spacing of 50 to 100 mm between the fixing devices, and the fitting deviation between the mold and the silicone plate is ≤0.1 mm.

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

10. The method for preparing ultra-high performance concrete slabs for construction according to claim 7, wherein: In step S3, the interval between the pouring of 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 thickness of the plastic film is 0.05 to 0.1 mm.

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