Low-shrinkage ultra-high-strength concrete and preparation method thereof
Patent Information
- Application Number
- CN202611018056.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-07-09
- Publication Date
- 2026-09-15
Smart Images
Figure CN122749028A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of concrete technology, and in particular to a low-shrinkage ultra-high-strength concrete and its preparation method. Background Technology
[0002] Currently, the improvement of concrete materials in terms of strength, functionality, and durability has become a key requirement in the engineering field. Ultra-high strength concrete has the characteristics of high strength, excellent corrosion resistance and durability. It can reduce structural size, reduce structural weight, save land, reduce energy consumption, and reduce structural maintenance and reconstruction costs. Therefore, its preparation and application technology has become one of the key concrete technologies studied in the construction industry.
[0003] However, ultra-high strength concrete typically has characteristics such as high cementitious material content, low water-cement ratio, and large admixture dosage. Additionally, its high slurry viscosity makes pumping difficult. While existing ultra-high strength concrete can achieve high strength, it still faces pumping difficulties due to high viscosity and the risk of cracking caused by high shrinkage.
[0004] While traditional expansion agents can compensate for shrinkage, they suffer from drawbacks such as excessively rapid early expansion and insufficient compensation in later stages, making them difficult to match the hydration process of high-strength concrete. Traditional methods typically involve replacing part of the cement with mineral admixtures to reduce shrinkage, but excessive admixture dosage can sacrifice early strength. Therefore, how to synergistically improve low viscosity, low shrinkage, and crack resistance and durability while ensuring ultra-high strength has become an urgent technical problem to be solved. Summary of the Invention
[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a low-shrinkage ultra-high-strength concrete and its preparation method.
[0006] A low-shrinkage, ultra-high-strength concrete comprises the following raw materials by weight: 80-120 parts cement, 50-70 parts fly ash, 5-15 parts silica fume, 5-15 parts composite aggregate, 150-250 parts manufactured sand, 150-200 parts crushed stone, 1-2 parts polycarboxylate superplasticizer, 2-4 parts shrinkage reducer, 0.2-0.8 parts superabsorbent resin, 15-30 parts composite fiber, and 30-45 parts water.
[0007] The raw materials of the composite aggregate, by weight, include: 8-12 parts of nano-grade lightly calcined magnesium oxide, 2-5 parts of ultrafine calcium sulfoaluminate clinker, 1-3 parts of anhydrous gypsum, 0.2-0.5 parts of dispersant, 10-30 parts of activated porous basalt, and 0.02-0.35 parts of tetraethyl orthosilicate.
[0008] Preferably, the cement is P·O 52.5R ordinary Portland cement.
[0009] Preferably, the fly ash is Class I fly ash.
[0010] Preferably, the manufactured sand is limestone manufactured sand with a particle size of 0.15-4.5 mm.
[0011] Preferably, the crushed stone is limestone crushed stone with a particle size of 5-8 mm.
[0012] Preferably, the polycarboxylate superplasticizer is a TPEG type polycarboxylate superplasticizer or an HPEG type polycarboxylate superplasticizer.
[0013] Preferably, the shrinkage reducing agent is a polyether-type shrinkage reducing agent.
[0014] Preferably, the superabsorbent resin is sodium polyacrylate resin.
[0015] Preferably, the composite fiber includes steel fiber, polypropylene fiber and alkali-resistant glass fiber, and the mass ratio of steel fiber, polypropylene fiber and alkali-resistant glass fiber is 1-2:1-4:1-2.
[0016] Preferably, the dispersant is a polycarboxylate dispersant.
[0017] Preferably, the composite aggregate is prepared by the following steps: water, nano-grade lightly calcined magnesium oxide, ultrafine calcium sulfoaluminate clinker, anhydrous gypsum, and dispersant are mixed evenly, activated porous basalt is added and ultrasonically treated for 10-20 minutes, vacuum impregnated for 20-40 minutes, and allowed to stand at normal pressure for 1-2 hours to remove the solvent. Then, a composite liquid containing tetraethyl orthosilicate is sprayed onto the surface of the resulting solid, and the solid is cured in a sealed state at a relative humidity ≥85% and a temperature of 35-45℃ for 12-24 hours, and then dried at 50-60℃ for 1-3 hours.
[0018] More preferably, the frequency of ultrasonic treatment is 30-50 kHz.
[0019] More preferably, the vacuum degree of vacuum impregnation is 0.02-0.04 MPa.
[0020] Preferably, the activated porous basalt is prepared as follows: porous basalt powder is soaked in a 3-5% (w / w) citric acid solution, activated at 50-60°C for 30-60 min, washed, and dried; then it is added to a 40-60% (w / w) ethanol aqueous solution, KH-570 silane coupling agent is added, the pH of the system is adjusted to 4-5, and stirred at 40-50°C for 1-2 h; subsequently, polyethylene glycol methacrylate, acrylic acid, and ammonium persulfate are added, and the grafting reaction is carried out at 70-80°C for 2-4 h. After the reaction is completed, the mixture is filtered, washed, and dried.
[0021] More preferably, the mass ratio of porous basalt powder, KH-570 silane coupling agent, polyethylene glycol methacrylate, acrylic acid, and ammonium persulfate is 10-30:1-2:8-12:3-6:0.1-0.3.
[0022] The preparation method of the above-mentioned low-shrinkage ultra-high-strength concrete includes the following steps: S1. Dry mix cement, fly ash, silica fume, and composite aggregate for 2-6 minutes. Add manufactured sand and crushed stone and continue dry mixing for 1-3 minutes. Add water, polycarboxylate superplasticizer, and shrinkage reducer and stir for 3-5 minutes. Then add super absorbent resin and water and continue stirring for 2-4 minutes to obtain the precast material. S2. Add composite fiber to the precast material and stir for 1-3 minutes until evenly dispersed. After casting and molding, cover with film to retain moisture, demold, and cure.
[0023] Preferably, in S1, the mass ratio of water added before and after is 15-25:15-20.
[0024] Preferably, in S2, the curing environment is a temperature of 20-25℃ and a relative humidity of not less than 95%.
[0025] Preferably, in S2, the curing time is 28 days.
[0026] Compared with existing technologies, the present invention has the following advantages: This invention uses activated porous basalt as a carrier. After acid activation, silane modification, and polyether segment grafting, its surface exhibits good dispersibility and interfacial compatibility. It can not only act as a micro-skeleton filler and lubricant in the cementitious system, reducing the frictional resistance in the slurry and improving the fluidity and pumpability of ultra-high strength concrete, but its pore structure can also support nano-sized lightly calcined magnesium oxide, ultrafine calcium sulfoaluminate clinker, and anhydrous gypsum. The activated porous basalt after loading is then cured with tetraethyl orthosilicate to form a surface coating layer, effectively avoiding the problems of excessively rapid early expansion and insufficient compensation in the later stage of traditional expansion agents, making the shrinkage compensation process more compatible with the hydration and hardening process of ultra-high strength concrete.
[0027] This invention utilizes a phased mixing process involving cement, fly ash, silica fume, composite aggregate, manufactured sand, crushed stone, water-reducing agent, shrinkage-reducing agent, and superabsorbent resin. This process ensures that the composite aggregate is evenly distributed between the cementitious material and the aggregate interface, forming a stable micro-filling and interface-controlled structure. The superabsorbent resin absorbs and stores water during the mixing stage and releases internal curing water during the hardening process. This alleviates the self-drying of the low water-cement ratio system and further activates the expansion components within the pores of the composite aggregate, achieving a synergistic effect of internal curing and delayed shrinkage compensation.
[0028] This invention does not rely solely on increasing the amount of mineral admixtures to reduce shrinkage. While ensuring ultra-high strength, it also enables concrete to have good pumpability, low shrinkage tendency, and excellent crack resistance and durability. Moreover, the preparation method is simple and suitable for large-scale promotion and use. Attached Figure Description
[0029] Figure 1The graph shows a comparison of the slump spread and 28-day compressive strength of the low-shrinkage ultra-high-strength concrete obtained in Example 5 and Comparative Examples 1-2.
[0030] Figure 2 The graph shows a comparison of the 28-day splitting tensile strength and 28-day elastic modulus of the low-shrinkage ultra-high-strength concrete obtained in Example 5 and Comparative Examples 1-2.
[0031] Figure 3 The graph shows a comparison of the 28-day autogenous shrinkage and 90-day drying shrinkage of the low-shrinkage ultra-high-strength concrete obtained in Example 5 and Comparative Examples 1-2. Detailed Implementation
[0032] The present invention will now be described in further detail with reference to specific embodiments. The given embodiments are merely illustrative of the invention and not intended to limit its scope. The embodiments provided below can serve as a guide for further improvements by those skilled in the art and do not constitute a limitation on the invention in any way.
[0033] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.
[0034] The manufactured sand used below is limestone manufactured sand, with a particle size range of 0.15-4.5 mm. The crushed stone used below is limestone crushed stone, with a particle size range of 5-8 mm. The porous basalt powder used below was purchased from Hebei Hengyue Mineral Products Co., Ltd., with a particle size of 80 μm. The polycarboxylate superplasticizer used below was purchased from Shandong Yuanlian Chemical Co., Ltd. The shrinkage reducing agent used below is from Evonik, brand name SITREN. ® SRAP 260. The sodium polyacrylate resin used below was purchased from Fuhe New Materials Technology (Shanghai) Co., Ltd. The polycarboxylate dispersant used below was purchased from Shenzhen Huiya New Materials Technology Co., Ltd., model HY-416.
[0035] The composite fibers used below are composed of steel fibers, polypropylene fibers and alkali-resistant glass fibers in a mass ratio of 1:3:2.
[0036] The composite solution containing tetraethyl orthosilicate used below was prepared by the following operation: 1.5g of tetraethyl orthosilicate was added to 35g of 50% ethanol aqueous solution, and the pH of the system was adjusted to 3 using 1mol / L hydrochloric acid.
[0037] Example 1: A low-shrinkage ultra-high strength concrete, the raw materials of which include: 800g of P·O 52.5R ordinary Portland cement, 500g of Grade I fly ash, 60g of silica fume, 50g of composite aggregate, 1500g of manufactured sand, 1500g of crushed stone, 10g of polycarboxylate superplasticizer, 20g of shrinkage reducer, 2g of sodium polyacrylate resin, 150g of composite fiber, and 300g of water.
[0038] The raw materials for the composite aggregate include: 80g of nano-grade lightly calcined magnesium oxide, 20g of ultrafine calcium sulfoaluminate clinker, 10g of anhydrous gypsum, 2g of polycarboxylate dispersant, 100g of activated porous basalt, and 0.2g of tetraethyl orthosilicate.
[0039] Activated porous basalt was prepared as follows: 100g of porous basalt powder was soaked in 1000g of 3% citric acid solution, activated at 50℃ for 30min, washed until neutral, and dried at 80℃ to constant weight; then added to 1000g of 40% ethanol aqueous solution, 10g of KH-570 silane coupling agent was added, the pH of the system was adjusted to 4, and stirred at 40℃ for 1h; subsequently, 80g of polyethylene glycol methacrylate, 30g of acrylic acid and 1g of ammonium persulfate were added, and the grafting reaction was carried out at 70℃ for 2h. After the reaction was completed, the mixture was filtered, washed and dried.
[0040] The composite aggregate is prepared by the following steps: 2000g of water, nano-grade lightly calcined magnesium oxide, ultrafine calcium sulfoaluminate clinker, anhydrous gypsum, and polycarboxylate dispersant are mixed evenly. Activated porous basalt is added and ultrasonically treated for 10 minutes at a frequency of 30kHz. Vacuum impregnation is carried out for 20 minutes under a vacuum of 0.02MPa. The mixture is then allowed to stand at normal pressure for 1 hour to remove the solvent. Finally, a composite liquid containing tetraethyl orthosilicate is sprayed onto the surface of the resulting solid. The mixture is then cured in a sealed state at a relative humidity ≥85% and a temperature of 35℃ for 12 hours, and dried at a temperature of 50℃ for 1 hour.
[0041] The preparation method of the above-mentioned low-shrinkage ultra-high-strength concrete includes the following steps: S1. Dry mix P·O 52.5R ordinary Portland cement, Grade I fly ash, silica fume, and composite aggregate at 100 r / min for 2 min. Add manufactured sand and crushed stone and continue dry mixing for 1 min. Add 150 g of water, polycarboxylate superplasticizer, and shrinkage reducer. Stir at 300 r / min for 3 min. Then add sodium polyacrylate resin and 150 g of water and continue stirring for 2 min to obtain the precast material. S2. Add composite fibers to the precast material and stir at 50 r / min for 1 min until evenly dispersed. After casting and molding, cover with a film to keep moist. Demold after 24 hours and cure for 28 days in an environment with a temperature of 20℃ and a relative humidity of not less than 95%.
[0042] Example 2: A low-shrinkage, ultra-high-strength concrete comprises the following raw materials: 1200g of P·O 52.5R ordinary Portland cement, 700g of Grade I fly ash, 80g of silica fume, 150g of composite aggregate, 2500g of manufactured sand, 2000g of crushed stone, 20g of polycarboxylate superplasticizer, 40g of shrinkage reducer, 8g of sodium polyacrylate resin, 300g of composite fiber, and 450g of water.
[0043] The raw materials for the composite aggregate include: 120g of nano-grade lightly calcined magnesium oxide, 50g of ultrafine calcium sulfoaluminate clinker, 30g of anhydrous gypsum, 5g of polycarboxylate dispersant, 300g of activated porous basalt, and 3.5g of tetraethyl orthosilicate.
[0044] Activated porous basalt was prepared as follows: 300g of porous basalt powder was soaked in 2000g of 5% citric acid solution, activated at 60℃ for 60min, washed until neutral, and dried at 95℃ to constant weight; then added to 2000g of 60% ethanol aqueous solution, 20g of KH-570 silane coupling agent was added, the pH of the system was adjusted to 5, and stirred at 50℃ for 2h; subsequently, 120g of polyethylene glycol methacrylate, 60g of acrylic acid and 3g of ammonium persulfate were added, and the grafting reaction was carried out at 80℃ for 4h. After the reaction was completed, the mixture was filtered, washed and dried.
[0045] The composite aggregate is prepared by the following steps: 4000g of water, nano-grade lightly calcined magnesium oxide, ultrafine calcium sulfoaluminate clinker, anhydrous gypsum, and polycarboxylate dispersant are mixed evenly. Activated porous basalt is added and ultrasonically treated for 20 minutes at a frequency of 50kHz. Vacuum impregnation is carried out for 40 minutes under a vacuum of 0.04MPa. The mixture is then allowed to stand at normal pressure for 2 hours to remove the solvent. Finally, a composite liquid containing tetraethyl orthosilicate is sprayed onto the surface of the resulting solid. The mixture is then cured in a sealed state at a relative humidity ≥85% and a temperature of 45℃ for 24 hours, and dried at a temperature of 60℃ for 3 hours.
[0046] The preparation method of the above-mentioned low-shrinkage ultra-high-strength concrete includes the following steps: S1. Dry mix P·O 52.5R ordinary Portland cement, Grade I fly ash, silica fume, and composite aggregate at 300 r / min for 6 min. Add manufactured sand and crushed stone and continue dry mixing for 3 min. Add 250 g of water, polycarboxylate superplasticizer, and shrinkage reducer. Stir at 500 r / min for 5 min. Then add sodium polyacrylate resin and 200 g of water and continue stirring for 4 min to obtain the precast material. S2. Add composite fibers to the precast material and stir at 100r / min for 3 minutes until evenly dispersed. After casting and molding, cover with a film to keep moist. Demold after 24 hours and cure for 28 days in an environment with a temperature of 22℃ and a relative humidity of not less than 95%.
[0047] Example 3: A low-shrinkage ultra-high-strength concrete, the raw materials of which include: 900g of P·O 52.5R ordinary Portland cement, 650g of Grade I fly ash, 150g of silica fume, 80g of composite aggregate, 2200g of manufactured sand, 1700g of crushed stone, 18g of polycarboxylate superplasticizer, 25g of shrinkage reducer, 6g of sodium polyacrylate resin, 180g of composite fiber, and 390g of water.
[0048] The raw materials for the composite aggregate include: 90g of nano-grade lightly calcined magnesium oxide, 40g of ultrafine calcium sulfoaluminate clinker, 15g of anhydrous gypsum, 4g of polycarboxylate dispersant, 150g of activated porous basalt, and 3g of tetraethyl orthosilicate.
[0049] Activated porous basalt was prepared as follows: 150g of porous basalt powder was soaked in 1800g of 3.5% citric acid solution, activated at 58℃ for 40min, washed until neutral, and dried at 105℃ to constant weight; then added to 1800g of 45% ethanol aqueous solution, 18g of KH-570 silane coupling agent was added, the pH of the system was adjusted to 4.5, and stirred at 42℃ for 100min; subsequently, 90g of polyethylene glycol methacrylate, 50g of acrylic acid and 1.5g of ammonium persulfate were added, and the grafting reaction was carried out at 77℃ for 2.5h. After the reaction was completed, the mixture was filtered, washed and dried.
[0050] The composite aggregate is prepared by the following steps: 3500g of water, nano-grade lightly calcined magnesium oxide, ultrafine calcium sulfoaluminate clinker, anhydrous gypsum, and polycarboxylate dispersant are mixed evenly. Activated porous basalt is added and ultrasonically treated for 12 minutes at a frequency of 45kHz. Vacuum impregnation is carried out for 35 minutes under a vacuum of 0.025MPa, followed by standing at normal pressure for 80 minutes to remove the solvent. Then, a composite liquid containing tetraethyl orthosilicate is sprayed onto the surface of the resulting solid. The solid is cured for 15 hours under sealed conditions at a relative humidity ≥85% and a temperature of 42℃, and then dried at a temperature of 58℃ for 1.5 hours.
[0051] The preparation method of the above-mentioned low-shrinkage ultra-high-strength concrete includes the following steps: S1. Dry mix P·O 52.5R ordinary Portland cement, Grade I fly ash, silica fume, and composite aggregate at 250 r / min for 3 min. Add manufactured sand and crushed stone and continue dry mixing for 2 min. Add 220 g of water, polycarboxylate superplasticizer, and shrinkage reducer. Stir at 350 r / min for 4.5 min. Then add sodium polyacrylate resin and 170 g of water and continue stirring for 3 min to obtain the precast material. S2. Add composite fibers to the precast material and stir at 90r / min for 2min until evenly dispersed. After casting and molding, cover with film to keep moist. Demold after 24h and cure for 28 days in an environment with a temperature of 25℃ and a relative humidity of not less than 95%.
[0052] Example 4: A low-shrinkage ultra-high-strength concrete, the raw materials of which include: 1100g of P·O 52.5R ordinary Portland cement, 550g of Grade I fly ash, 50g of silica fume, 120g of composite aggregate, 1800g of manufactured sand, 1800g of crushed stone, 12g of polycarboxylate superplasticizer, 35g of shrinkage reducer, 4g of sodium polyacrylate resin, 280g of composite fiber, and 360g of water.
[0053] The raw materials for the composite aggregate include: 110g of nano-grade lightly calcined magnesium oxide, 30g of ultrafine calcium sulfoaluminate clinker, 25g of anhydrous gypsum, 3g of polycarboxylate dispersant, 250g of activated porous basalt, and 1g of tetraethyl orthosilicate.
[0054] Activated porous basalt was prepared as follows: 250g of porous basalt powder was soaked in 1200g of 4.5% citric acid solution, activated at 52℃ for 50min, washed until neutral, and dried at 105℃ to constant weight; then added to 1200g of 55% ethanol aqueous solution, 12g of KH-570 silane coupling agent was added, the pH of the system was adjusted to 4.5, and stirred at 48℃ for 80min; subsequently, 110g of polyethylene glycol methacrylate, 40g of acrylic acid and 2.5g of ammonium persulfate were added, and the grafting reaction was carried out at 73℃ for 3.5h. After the reaction was completed, the mixture was filtered, washed and dried.
[0055] The composite aggregate is prepared by the following steps: 2500g of water, nano-grade lightly calcined magnesium oxide, ultrafine calcium sulfoaluminate clinker, anhydrous gypsum, and polycarboxylate dispersant are mixed evenly. Activated porous basalt is added and ultrasonically treated for 18 minutes at a frequency of 35kHz. Vacuum impregnation is carried out for 25 minutes under a vacuum of 0.035MPa. The mixture is then allowed to stand at normal pressure for 100 minutes to remove the solvent. Finally, a composite liquid containing tetraethyl orthosilicate is sprayed onto the surface of the resulting solid. The mixture is then cured for 21 hours at a relative humidity ≥85% and a temperature of 38℃ under sealed conditions, and dried at a temperature of 52℃ for 2.5 hours.
[0056] The preparation method of the above-mentioned low-shrinkage ultra-high-strength concrete includes the following steps: S1. Dry mix P·O 52.5R ordinary Portland cement, Grade I fly ash, silica fume, and composite aggregate at 150 r / min for 5 min. Add manufactured sand and crushed stone and continue dry mixing for 2 min. Add 180 g of water, polycarboxylate superplasticizer, and shrinkage reducer. Stir at 450 r / min for 3.5 min. Then add sodium polyacrylate resin and 180 g of water and continue stirring for 3 min to obtain the precast material. S2. Add composite fibers to the precast material and stir at 70r / min for 2min until evenly dispersed. After casting and molding, cover with a film to keep moist. Demold after 24 hours and cure for 28 days in an environment with a temperature of 25℃ and a relative humidity of not less than 95%.
[0057] Example 5: A low-shrinkage ultra-high strength concrete, the raw materials of which include: 1000g of P·O 52.5R ordinary Portland cement, 600g of Grade I fly ash, 100g of silica fume, 100g of composite aggregate, 2000g of manufactured sand, 1750g of crushed stone, 15g of polycarboxylate superplasticizer, 30g of shrinkage reducer, 5g of sodium polyacrylate resin, 230g of composite fiber, and 375g of water.
[0058] The raw materials for the composite aggregate include: 100g of nano-grade lightly calcined magnesium oxide, 35g of ultrafine calcium sulfoaluminate clinker, 20g of anhydrous gypsum, 3.5g of polycarboxylate dispersant, 200g of activated porous basalt, and 2g of tetraethyl orthosilicate.
[0059] Activated porous basalt was prepared as follows: 200g of porous basalt powder was soaked in 1500g of 4% citric acid solution, activated at 55℃ for 45min, washed until neutral, and dried at 105℃ to constant weight; then it was added to 1500g of 50% ethanol aqueous solution, 15g of KH-570 silane coupling agent was added, the pH of the system was adjusted to 4.5, and stirred at 45℃ for 90min; subsequently, 100g of polyethylene glycol methacrylate, 45g of acrylic acid and 2g of ammonium persulfate were added, and the grafting reaction was carried out at 75℃ for 3h. After the reaction was completed, the mixture was filtered, washed and dried.
[0060] The composite aggregate is prepared by the following steps: 3000g of water, nano-grade lightly calcined magnesium oxide, ultrafine calcium sulfoaluminate clinker, anhydrous gypsum, and polycarboxylate dispersant are mixed evenly. Activated porous basalt is added and ultrasonically treated for 15 minutes at a frequency of 40kHz. Vacuum impregnation is carried out for 30 minutes under a vacuum of 0.03MPa, followed by standing at normal pressure for 90 minutes to remove the solvent. Then, a composite liquid containing tetraethyl orthosilicate is sprayed onto the surface of the resulting solid. The solid is cured for 18 hours under sealed conditions at a relative humidity ≥85% and a temperature of 40℃, and then dried at a temperature of 55℃ for 2 hours.
[0061] The preparation method of the above-mentioned low-shrinkage ultra-high-strength concrete includes the following steps: S1. Dry mix P·O 52.5R ordinary Portland cement, Grade I fly ash, silica fume, and composite aggregate at 200 r / min for 4 min. Add manufactured sand and crushed stone and continue dry mixing for 2 min. Add 200 g of water, polycarboxylate superplasticizer, and shrinkage reducer. Stir at 400 r / min for 4 min. Then add sodium polyacrylate resin and 175 g of water and continue stirring for 3 min to obtain the precast material. S2. Add composite fibers to the precast material and stir at 80r / min for 2min until evenly dispersed. After casting and molding, cover with film to keep moist. Demold after 24h and cure for 28 days in an environment with a temperature of 25℃ and a relative humidity of not less than 95%.
[0062] Comparative Example 1: An ultra-high strength concrete, the raw materials of which include: 1000g of P·O 52.5R ordinary Portland cement, 600g of Grade I fly ash, 100g of silica fume, 100g of composite aggregate, 2000g of manufactured sand, 1750g of crushed stone, 15g of polycarboxylate superplasticizer, 30g of shrinkage reducer, 5g of sodium polyacrylate resin, 230g of composite fiber, and 375g of water.
[0063] The raw materials for the composite aggregate include: 100g of nano-grade lightly calcined magnesium oxide, 35g of ultrafine calcium sulfoaluminate clinker, 20g of anhydrous gypsum, 3.5g of polycarboxylate dispersant, 200g of activated porous basalt, and 2g of tetraethyl orthosilicate.
[0064] Activated porous basalt was prepared as follows: 200g of porous basalt powder was soaked in 1500g of 4% citric acid solution, activated at 55℃ for 45min, washed until neutral, and dried at 105℃ to constant weight.
[0065] The composite aggregate is prepared by the following steps: 3000g of water, nano-grade lightly calcined magnesium oxide, ultrafine calcium sulfoaluminate clinker, anhydrous gypsum, and polycarboxylate dispersant are mixed evenly. Activated porous basalt is added and ultrasonically treated for 15 minutes at a frequency of 40kHz. Vacuum impregnation is carried out for 30 minutes under a vacuum of 0.03MPa, followed by standing at normal pressure for 90 minutes to remove the solvent. Then, a composite liquid containing tetraethyl orthosilicate is sprayed onto the surface of the resulting solid. The solid is cured for 18 hours under sealed conditions at a relative humidity ≥85% and a temperature of 40℃, and then dried at a temperature of 55℃ for 2 hours.
[0066] The above-mentioned method for preparing ultra-high strength concrete includes the following steps: S1. Dry mix P·O 52.5R ordinary Portland cement, Grade I fly ash, silica fume, and composite aggregate at 200 r / min for 4 min. Add manufactured sand and crushed stone and continue dry mixing for 2 min. Add 200 g of water, polycarboxylate superplasticizer, and shrinkage reducer. Stir at 400 r / min for 4 min. Then add sodium polyacrylate resin and 175 g of water and continue stirring for 3 min to obtain the precast material. S2. Add composite fibers to the precast material and stir at 80r / min for 2min until evenly dispersed. After casting and molding, cover with film to keep moist. Demold after 24h and cure for 28 days in an environment with a temperature of 25℃ and a relative humidity of not less than 95%.
[0067] Comparative Example 2: An ultra-high strength concrete, the raw materials of which include: 1000g of P·O 52.5R ordinary Portland cement, 600g of Grade I fly ash, 100g of silica fume, 100g of composite aggregate, 2000g of manufactured sand, 1750g of crushed stone, 15g of polycarboxylate superplasticizer, 30g of shrinkage reducer, 5g of sodium polyacrylate resin, 230g of composite fiber, and 375g of water.
[0068] The raw materials for the composite aggregate include: 100g of nano-grade lightly calcined magnesium oxide, 35g of ultrafine calcium sulfoaluminate clinker, 20g of anhydrous gypsum, 3.5g of polycarboxylate dispersant, and 200g of activated porous basalt.
[0069] Activated porous basalt was prepared as follows: 200g of porous basalt powder was soaked in 1500g of 4% citric acid solution, activated at 55℃ for 45min, washed until neutral, and dried at 105℃ to constant weight; then it was added to 1500g of 50% ethanol aqueous solution, 15g of KH-570 silane coupling agent was added, the pH of the system was adjusted to 4.5, and stirred at 45℃ for 90min; subsequently, 100g of polyethylene glycol methacrylate, 45g of acrylic acid and 2g of ammonium persulfate were added, and the grafting reaction was carried out at 75℃ for 3h. After the reaction was completed, the mixture was filtered, washed and dried.
[0070] The composite aggregate is prepared by the following steps: nano-sized lightly calcined magnesium oxide, ultrafine calcium sulfoaluminate clinker, anhydrous gypsum, and polycarboxylate dispersant are mixed evenly, and then activated porous basalt is added and mixed evenly.
[0071] The above-mentioned method for preparing ultra-high strength concrete includes the following steps: S1. Dry mix P·O 52.5R ordinary Portland cement, Grade I fly ash, silica fume, and composite aggregate at 200 r / min for 4 min. Add manufactured sand and crushed stone and continue dry mixing for 2 min. Add 200 g of water, polycarboxylate superplasticizer, and shrinkage reducer. Stir at 400 r / min for 4 min. Then add sodium polyacrylate resin and 175 g of water and continue stirring for 3 min to obtain the precast material. S2. Add composite fibers to the precast material and stir at 80r / min for 2min until evenly dispersed. After casting and molding, cover with film to keep moist. Demold after 24h and cure for 28 days in an environment with a temperature of 25℃ and a relative humidity of not less than 95%.
[0072] The slump spread of the ultra-high strength concrete obtained in Example 5 and Comparative Examples 1-2 was determined with reference to GB / T 50080-2016 "Standard for Test Methods of Performance of Ordinary Concrete Mixtures".
[0073] The 28-day compressive strength, 28-day splitting tensile strength, and 28-day modulus of elasticity of the ultra-high strength concrete obtained in Example 5 and Comparative Examples 1-2 were determined with reference to GB / T 50081-2019 "Standard for Test Methods of Physical and Mechanical Properties of Concrete".
[0074] like Figure 1 and Figure 2 As shown, the ultra-high strength concrete obtained in Example 5 has the highest slump expansion, 28-day compressive strength, 28-day splitting tensile strength, and 28-day modulus of elasticity, which are significantly better than the comparative example.
[0075] The 28-day autogenous shrinkage and 90-day drying shrinkage of the ultra-high strength concrete obtained in Example 5 and Comparative Examples 1-2 were measured in accordance with GB / T 50082-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete".
[0076] like Figure 3 As shown, the ultra-high strength concrete obtained in Example 5 exhibits the lowest 28-day autogenous shrinkage and 90-day drying shrinkage, significantly superior to the comparative example.
[0077] The present invention has been described in detail above. Those skilled in the art will recognize that the invention can be practiced in a wide range of ways with equivalent parameters, concentrations, and conditions without departing from its spirit and scope, and without requiring unnecessary experiments. While specific embodiments have been provided, it should be understood that further modifications can be made to the invention. In summary, according to the principles of the invention, this application is intended to include any changes, uses, or improvements to the invention, including changes made using conventional techniques known in the art that depart from the scope disclosed herein.
Claims
1. A low-shrinkage, ultra-high-strength concrete, characterized in that, Its raw materials, by weight, include: 80-120 parts cement, 50-70 parts fly ash, 5-15 parts silica fume, 5-15 parts composite aggregate, 150-250 parts manufactured sand, 150-200 parts crushed stone, 1-2 parts polycarboxylate superplasticizer, 2-4 parts shrinkage reducer, 0.2-0.8 parts superabsorbent resin, 15-30 parts composite fiber, and 30-45 parts water. The raw materials of the composite aggregate, by weight, include: 8-12 parts of nano-grade lightly calcined magnesium oxide, 2-5 parts of ultrafine calcium sulfoaluminate clinker, 1-3 parts of anhydrous gypsum, 0.2-0.5 parts of dispersant, 10-30 parts of activated porous basalt, and 0.02-0.35 parts of tetraethyl orthosilicate.
2. The low-shrinkage ultra-high-strength concrete according to claim 1, characterized in that, The polycarboxylate superplasticizer is either a TPEG type or an HPEG type.
3. The low-shrinkage ultra-high-strength concrete according to claim 1, characterized in that, The shrinkage reducing agent is a polyether-type shrinkage reducing agent.
4. The low-shrinkage ultra-high-strength concrete according to claim 1, characterized in that, The superabsorbent resin is sodium polyacrylate resin.
5. The low-shrinkage ultra-high-strength concrete according to claim 1, characterized in that, The composite fibers include steel fibers, polypropylene fibers, and alkali-resistant glass fibers, with a mass ratio of 1-2:1-4:1-2.
6. The low-shrinkage ultra-high-strength concrete according to claim 1, characterized in that, The composite aggregate is prepared by the following steps: water, nano-grade lightly calcined magnesium oxide, ultrafine calcium sulfoaluminate clinker, anhydrous gypsum, and dispersant are mixed evenly. Activated porous basalt is added and ultrasonically treated for 10-20 minutes, vacuum impregnated for 20-40 minutes, and allowed to stand at normal pressure for 1-2 hours to remove the solvent. Then, a composite liquid containing tetraethyl orthosilicate is sprayed onto the surface of the resulting solid. Under sealed conditions, it is cured at a relative humidity ≥85% and a temperature of 35-45℃ for 12-24 hours, and then dried at 50-60℃ for 1-3 hours.
7. The low-shrinkage ultra-high-strength concrete according to claim 6, characterized in that, The frequency of ultrasonic treatment is 30-50kHz; the vacuum degree of vacuum impregnation is 0.02-0.04MPa.
8. The low-shrinkage ultra-high-strength concrete according to claim 1, characterized in that, Activated porous basalt was prepared as follows: Porous basalt powder was soaked in a 3-5% (w / w) citric acid solution and activated at 50-60℃ for 30-60 min, then washed and dried; then it was added to a 40-60% (w / w) ethanol aqueous solution, KH-570 silane coupling agent was added, the pH of the system was adjusted to 4-5, and the mixture was stirred at 40-50℃ for 1-2 h; subsequently, polyethylene glycol methacrylate, acrylic acid and ammonium persulfate were added, and the grafting reaction was carried out at 70-80℃ for 2-4 h. After the reaction was completed, the mixture was filtered, washed and dried.
9. The low-shrinkage ultra-high-strength concrete according to claim 1, characterized in that, The mass ratio of porous basalt powder, KH-570 silane coupling agent, polyethylene glycol methacrylate, acrylic acid, and ammonium persulfate is 10-30:1-2:8-12:3-6:0.1-0.
3.
10. A method for preparing low-shrinkage ultra-high-strength concrete as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Dry mix cement, fly ash, silica fume, and composite aggregate for 2-6 minutes. Add manufactured sand and crushed stone and continue dry mixing for 1-3 minutes. Add water, polycarboxylate superplasticizer, and shrinkage reducer and stir for 3-5 minutes. Then add super absorbent resin and water and continue stirring for 2-4 minutes to obtain the precast material. S2. Add composite fiber to the precast material and stir for 1-3 minutes until evenly dispersed. After casting and molding, cover with film to retain moisture, demold, and cure.