Ultra-high performance concrete and method for producing the same

Abstract

The application provides an ultra-high performance concrete and a preparation method thereof, and the concrete comprises the following raw materials in parts by weight: cement 260-280 parts, modified quartz sand powder 120-160 parts, modified steel fiber 8-15 parts, fly ash 20-26 parts, polycarboxylic acid water reducing agent 7-12 parts, EVA emulsion 16-24 parts, alkali-resistant glass fiber 4-7 parts, and water 140-180 parts. The preparation method of the modified steel fiber is as follows: the steel fiber is soaked in a potassium hydroxide solution and then dried, the dried steel fiber is added into a calcium hydroxide slurry, potassium carbonate is added for a first stirring reaction, a mixed solution of nano-SiO2 and a coupling agent is further added for a second stirring reaction, filtration and drying are performed, and the modified steel fiber is obtained. The ultra-high performance concrete prepared by the application has scientific proportioning of various raw materials, good toughness, strength and crack resistance, and can effectively improve the service life of the concrete.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of concrete material preparation, in particular to a kind of ultra-high performance concrete and preparation method thereof. BACKGROUND

[0002] Ultra-high performance concrete (UHPC) is a kind of cement-based composite material, with good mechanical properties, toughness and durability. Compared with ordinary cement, ultra-high performance concrete can reduce the use of a large amount of materials, reduce cost, save resources. Steel fiber is an important material for enhancing the toughness and strength of ultra-high performance concrete, in order to prevent steel fiber from rusting, it is usually necessary to carry out metal plating treatment on steel fiber to form a smooth protective layer. Thus, the interfacial adhesion between steel fiber and other composite materials is poor, leading to uneven mixing of cement-based composite materials, resulting in air holes in the use process of ultra-high performance concrete, and later cracking and other problems, and reducing the compressive strength and tensile strength of concrete. SUMMARY

[0003] In view of this, the present application provides an ultra-high performance concrete and a preparation method thereof. The ultra-high performance concrete of the present application can effectively enhance the adhesion strength of steel fiber and other composite materials while ensuring the strength and toughness of concrete in the use process, improve the uniform dispersibility of concrete material, reduce the later cracking phenomenon of concrete, and effectively improve the performance of concrete.

[0004] The technical scheme of the present application is as follows:

[0005] An ultra-high performance concrete, comprising the following raw materials by weight: cement 260-280 parts, modified quartz sand powder 120-160 parts, modified steel fiber 8-15 parts, fly ash 20-26 parts, polycarboxylate superplasticizer 7-12 parts, EVA emulsion 16-24 parts, alkali-resistant glass fiber 4-7 parts, and water 140-180 parts.

[0006] The preparation method of the modified steel fiber is as follows: the steel fiber is soaked in a potassium hydroxide solution and then dried, the dried steel fiber is added to a calcium hydroxide slurry, potassium carbonate is then added for a first stirring reaction, and then a mixed solution of nano-SiO2 and coupling agent is added for a second stirring reaction, followed by filtration and drying to obtain the modified steel fiber.

[0007] Further, the ultra-high performance concrete has the following characteristics: the mass ratio of the steel fiber, calcium hydroxide slurry, potassium carbonate and the mixed solution is 4-5:2-4:5-7:3-6; the concentration of the potassium hydroxide solution is 12-16 wt%; the concentration of the calcium hydroxide slurry is 2.0-5.0 wt%; and the coupling agent is one or a combination of two or more of silane coupling agent, titanate coupling agent or aluminate coupling agent.

[0008] Furthermore, the conditions for the first stirring reaction are as follows: stirring for 8-10 seconds with an interval of 8-10 seconds at a temperature of 65-80℃ and a stirring speed of 45-60r / min, with a total stirring time of 6-10min, and then increasing the stirring speed to 200-300r / min for 1-3h.

[0009] Furthermore, the preparation process of the mixed solution of nano-SiO2 and coupling agent is as follows: nano-SiO2, coupling agent and water are taken in a mass ratio of 1-2:0.1-0.3:2-3. Nano-SiO2 is added to water and stirred and mixed evenly. Then the coupling agent is added and stirred and mixed evenly to obtain the mixed solution of nano-SiO2 and coupling agent.

[0010] Furthermore, the secondary stirring reaction conditions are as follows: the reaction is carried out at a temperature of 50-70℃ and a stirring speed of 400-600 r / min for 30-60 min.

[0011] Furthermore, the preparation method of the modified quartz sand powder is as follows: Quartz sand powder, graphene oxide, and polyethylene glycol solution are taken in a mass ratio of 3-5:1-3:6-8. Graphene oxide is added to polyethylene glycol solution and stirred and mixed. Quartz sand powder is then added and stirred and mixed. The mixture is then ultrasonically dispersed, filtered, and the filter residue is dried and pulverized to obtain modified quartz sand powder.

[0012] Furthermore, the modified quartz sand powder has a particle size of 40-60 mesh.

[0013] Furthermore, the concentration of the polyethylene glycol solution is 20-30 wt%.

[0014] The preparation method of this ultra-high performance concrete includes the following steps: cement, modified quartz sand powder, modified steel fiber, fly ash and alkali-resistant glass fiber are mixed evenly according to the proportion, and then polycarboxylate superplasticizer, EVA emulsion and water are added and mixed evenly. The mixture is then poured into a mold and cast to form ultra-high performance concrete.

[0015] Furthermore, the concentration of the EVA emulsion is 50-60 wt%.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] The prepared ultra-high performance concrete has scientific proportioning of each raw material, so that the concrete has good toughness, strength and crack resistance, and the service life of the concrete can be effectively improved. The calcium carbonate whisker and nano-SiO2 can be filled and attached on the steel fiber by modifying the steel fiber, so as to improve the bonding strength and dispersion performance of the steel fiber and the cement-based material, thereby improving the uniformity of the concrete material, reducing the cracking phenomenon of the concrete in the later period, improving the performance of the concrete, and effectively preventing the corrosion of the steel fiber and improving the service life. In the preparation process, the graphene oxide and the quartz sand powder are compounded, so that the graphene oxide and the quartz sand powder form a uniform network structure, improve the uniform dispersibility of the concrete material, prevent micro-cracks in the concrete, and the modified quartz sand can be better bonded with the steel fiber material, so as to improve the compactness of the concrete, thereby improving the toughness and crack resistance of the concrete, and improving the corrosion resistance and service life of the steel fiber. DETAILED DESCRIPTION

[0018] In order to better understand the technical content of the present application, the following specific examples are provided to further illustrate the present application.

[0019] The experimental methods used in the embodiments of the present application are conventional methods unless otherwise specified.

[0020] The materials, reagents and the like used in the embodiments of the present application can be obtained from commercial channels unless otherwise specified.

[0021] Example 1

[0022] The ultra-high performance concrete of this example comprises the following raw materials by weight: cement 270 parts, modified quartz sand powder 150 parts, modified steel fiber 9 parts, fly ash 24 parts, polycarboxylic acid water reducer 10 parts, EVA emulsion with a concentration of 50wt% 18 parts, alkali-resistant glass fiber 5 parts, and water 170 parts.

[0023] The steel fiber, calcium hydroxide slurry with a concentration of 3.0wt%, potassium carbonate, nano-SiO2 and the mixed solution of the coupling agent are weighed according to the mass ratio of 5:3:7:4;

[0024] The preparation process of the mixed solution of nano-SiO2 and the coupling agent is as follows: nano-SiO2, silane coupling agent and water are taken according to the mass ratio of 1:0.2:3, the nano-SiO2 is added into the water and stirred to mix uniformly, and then the coupling agent is added and stirred to mix uniformly, so as to obtain the mixed solution of nano-SiO2 and the silane coupling agent;

[0025] The preparation method of the modified steel fiber is as follows: the steel fiber is soaked in a 13wt% potassium hydroxide solution and then dried, the dried steel fiber is added into a calcium hydroxide slurry, potassium carbonate is further added, and then the mixture is stirred at a temperature of 70 DEG C and a stirring speed of 50 r / min for 10 s intermittently for 7 min, then the stirring speed is increased to 200 r / min for reaction for 2 h, then a mixed solution of nano-SiO2 and coupling agent is further added, and then the mixture is reacted at a temperature of 60 DEG C and a stirring speed of 500 r / min for 40 min, and then the mixture is filtered and dried to obtain the modified steel fiber.

[0026] The preparation method of the super high performance concrete comprises the following steps: cement, modified quartz sand powder, modified steel fiber, fly ash and alkali-resistant glass fiber are uniformly stirred and mixed according to proportions, polycarboxylic acid water reducing agent, EVA emulsion and water are further uniformly stirred and mixed, and then the mixture is poured into a mold for casting and forming to obtain the super high performance concrete.

[0027] Example 2

[0028] The super high performance concrete of the example comprises the following raw materials in parts by weight: cement 265 parts, modified quartz sand powder 140 parts, modified steel fiber 12 parts, fly ash 22 parts, polycarboxylic acid water reducing agent 9 parts, EVA emulsion with a concentration of 55wt% 16 parts, alkali-resistant glass fiber 6 parts and water 150 parts.

[0029] Steel fiber, calcium hydroxide slurry with a concentration of 2.5wt%, potassium carbonate, a mixed solution of nano-SiO2 and coupling agent are weighed according to a mass ratio of 4:2:5:6; wherein the coupling agent is a mixture of silane coupling agent and titanate coupling agent in a mass ratio of 1:1;

[0030] The preparation process of the mixed solution of nano-SiO2 and coupling agent is as follows: nano-SiO2, coupling agent and water are taken according to a mass ratio of 2:0.1:2, the nano-SiO2 is added into the water and stirred and mixed uniformly, and then the coupling agent is added and stirred and mixed uniformly to obtain the mixed solution of nano-SiO2 and coupling agent;

[0031] The preparation method of the modified steel fiber is as follows: the steel fiber is soaked in a 15wt% potassium hydroxide solution and then dried, the dried steel fiber is added into a calcium hydroxide slurry, potassium carbonate is further added, and then the mixture is stirred at a temperature of 65 DEG C and a stirring speed of 45 r / min for 8 s intermittently for 6 min, then the stirring speed is increased to 250 r / min for reaction for 3 h, then a mixed solution of nano-SiO2 and coupling agent is further added, and then the mixture is reacted at a temperature of 50 DEG C and a stirring speed of 400 r / min for 30 min, and then the mixture is filtered and dried to obtain the modified steel fiber;

[0032] The preparation method of the super high performance concrete comprises the following steps: uniformly stirring cement, modified quartz sand powder, modified steel fiber, fly ash and alkali-resistant glass fiber according to proportions, then uniformly stirring and stirring polycarboxylic acid water reducing agent, EVA emulsion and water, pouring into a mold, and pouring and forming to obtain the super high performance concrete.

[0033] Example 3

[0034] The super high performance concrete of the example comprises the following raw materials in parts by weight: cement 260 parts, modified quartz sand powder 120 parts, modified steel fiber 8 parts, fly ash 20 parts, polycarboxylic acid water reducing agent 7 parts, EVA emulsion with a concentration of 50wt% 20 parts, alkali-resistant glass fiber 4 parts, and water 140 parts.

[0035] Steel fiber, a mixed solution of calcium hydroxide slurry with a concentration of 5.0wt%, potassium carbonate, nano-SiO2 and silane coupling agent are weighed according to a mass ratio of 5:3:6:5; wherein the coupling agent is a mixture of silane coupling agent, titanate coupling agent and aluminate coupling agent according to a mass ratio of 1:1:1;

[0036] The preparation process of the mixed solution of nano-SiO2 and coupling agent is as follows: nano-SiO2, silane coupling agent and water are taken according to a mass ratio of 2:0.3:2, the nano-SiO2 is added to the water and stirred and mixed uniformly, then the silane coupling agent is added and stirred and mixed uniformly, to obtain the mixed solution of nano-SiO2 and silane coupling agent;

[0037] The preparation method of the modified steel fiber is as follows: the steel fiber is soaked in a potassium hydroxide solution with a concentration of 16wt% and then dried, the dried steel fiber is added to the calcium hydroxide slurry, then the potassium carbonate is added, and stirring is carried out at a temperature of 75℃ and a stirring speed of 55r / min for 9min with 10s intervals, then the stirring speed is increased to 300r / min for reaction for 2h, then the mixed solution of nano-SiO2 and coupling agent is added, and stirring is carried out at a temperature of 70℃ and a stirring speed of 600r / min for 60min, then filtration and drying are carried out, to obtain the modified steel fiber;

[0038] The preparation method of the modified quartz sand powder is as follows: quartz sand powder, graphene oxide and polyethylene glycol solution with a concentration of 20wt% are taken according to a mass ratio of 4:2:8, the graphene oxide is added to the polyethylene glycol solution and stirred and mixed uniformly, then the quartz sand powder is added and stirred and mixed uniformly and ultrasonic dispersion is carried out, the filter residue is obtained by filtration, and then drying and crushing are carried out, to obtain the modified quartz sand powder;

[0039] The preparation method of the super high performance concrete comprises the following steps: uniformly stirring cement, modified quartz sand powder, modified steel fiber, fly ash and alkali-resistant glass fiber according to proportions, then uniformly stirring polycarboxylic acid water reducing agent, EVA emulsion and water, and pouring the mixture into a mold after the stirring to form a super high performance concrete.

[0040] Example 4

[0041] The super high performance concrete of the example comprises the following raw materials in parts by weight: cement 280 parts, modified quartz sand powder 160 parts, modified steel fiber 15 parts, fly ash 26 parts, polycarboxylic acid water reducing agent 12 parts, EVA emulsion with a concentration of 60wt% 24 parts, alkali-resistant glass fiber 7 parts, and water 180 parts.

[0042] The steel fiber, calcium hydroxide slurry with a concentration of 4.0wt%, potassium carbonate, nano-SiO2 and the mixed solution of coupling agents are weighed according to a mass ratio of 4:4:6:3; wherein the coupling agent is a mixture of silane coupling agent and aluminate coupling agent according to a mass ratio of 2:1;

[0043] The preparation process of the mixed solution of nano-SiO2 and coupling agents is as follows: nano-SiO2, coupling agents and water are taken according to a mass ratio of 1:0.2:3, the nano-SiO2 is added into the water and stirred to be uniformly mixed, then the coupling agents are added and stirred to be uniformly mixed, and a mixed solution of nano-SiO2 and coupling agents is obtained;

[0044] The preparation method of the modified steel fiber is as follows: the steel fiber is soaked in a potassium hydroxide solution with a concentration of 12wt% and then dried, the dried steel fiber is added into the calcium hydroxide slurry, potassium carbonate is added, and stirring is carried out at a temperature of 80℃ and a stirring speed of 60r / min for 8s intermittently for 9s for a total stirring time of 10min, then the stirring speed is increased to 200r / min for reaction for 1h, then the mixed solution of nano-SiO2 and coupling agents is added, and stirring is carried out at a temperature of 55℃ and a stirring speed of 450r / min for reaction for 50min, then filtration and drying are carried out, and a modified steel fiber is obtained;

[0045] The preparation method of the modified quartz sand powder is as follows: quartz sand powder, graphene oxide and polyethylene glycol solution with a concentration of 30wt% are taken according to a mass ratio of 5:3:7, the graphene oxide is added into the polyethylene glycol solution and stirred to be uniformly mixed, then the quartz sand powder is added and stirred to be uniformly mixed, ultrasonic dispersion is carried out, the filter residue is taken after filtration, and drying and crushing are carried out, and a modified quartz sand powder is obtained;

[0046] The preparation method of the super high performance concrete comprises the following steps: uniformly stirring cement, modified quartz sand powder, modified steel fiber, fly ash and alkali-resistant glass fiber according to proportions, then uniformly stirring polycarboxylic acid water reducing agent, EVA emulsion and water, and pouring the mixture into a mold after the stirring to form a super high performance concrete.

[0047] Comparative Example 1

[0048] The raw material formula of the concrete of this comparative example is different from that of Example 1, as follows:

[0049] The ultra-high performance concrete comprises the following raw materials by weight: cement 300 parts, modified quartz sand powder 200 parts, modified steel fiber 35 parts, fly ash 16 parts, polycarboxylic acid water reducer 18 parts, EVA emulsion with a concentration of 30wt% 12 parts, alkali-resistant glass fiber 12 parts, and water 100 parts.

[0050] Comparative Example 2

[0051] The steel fiber of this comparative example is not modified compared with Example 1, as follows:

[0052] The ultra-high performance concrete of this comparative example comprises the following raw materials by weight: cement 270 parts, modified quartz sand powder 150 parts, steel fiber 9 parts, fly ash 24 parts, polycarboxylic acid water reducer 10 parts, EVA emulsion with a concentration of 50wt% 18 parts, alkali-resistant glass fiber 5 parts, and water 170 parts.

[0053] The preparation method of the ultra-high performance concrete comprises the following steps: mixing the cement, modified quartz sand powder, steel fiber, fly ash, and alkali-resistant glass fiber in proportion, then adding the polycarboxylic acid water reducer, EVA emulsion, and water to mix uniformly, pouring into a mold, and pouring and forming, to obtain the ultra-high performance concrete.

[0054] Comparative Example 3

[0055] The quartz sand powder and steel fiber of this comparative example are not modified compared with Example 1, as follows:

[0056] The ultra-high performance concrete of this example comprises the following raw materials by weight: cement 270 parts, quartz sand powder 150 parts, modified steel fiber 9 parts, fly ash 24 parts, polycarboxylic acid water reducer 10 parts, EVA emulsion with a concentration of 50wt% 18 parts, alkali-resistant glass fiber 5 parts, and water 170 parts.

[0057] The preparation method of the ultra-high performance concrete comprises the following steps: mixing the cement, quartz sand powder, steel fiber, fly ash, and alkali-resistant glass fiber in proportion, then adding the polycarboxylic acid water reducer, EVA emulsion, and water to mix uniformly, pouring into a mold, and pouring and forming, to obtain the ultra-high performance concrete.

[0058] The flexural and compressive strengths of the ultra-high performance concrete are tested according to GB / T50081-2019 "Standard for Testing Methods of Physical and Mechanical Properties of Concrete".

[0059] The raw materials of the ultra-high performance concrete of the above-mentioned examples 1-4 and comparative examples 1-3 are respectively prepared into sample concrete pieces with a size of 100 mm x 100 mm x 400 mm, and then cured for 28 days under the condition of a temperature of 20 DEG C and a humidity of > 95%, and the anti-cracking strength, the compressive strength and the tensile strength are tested according to the standard of GB / T50081-2019 "Test methods of physical and mechanical properties of concrete".

[0060] Breaking strength / MPa Compressive strength / MPa Tensile strength / MPa Example 1 17.78 168.51 25.42 Example 2 18.45 170.84 25.76 Example 3 19.03 176.46 26.02 Example 4 19.62 181.23 26.43 Comparative Example 1 15.27 152.72 21.39 Comparative Example 2 14.52 141.83 19.54 Comparative Example 3 12.91 138.90 18.67

[0061] The above results show that the ultra-high performance concrete prepared by the examples 1-4 of the present application has good anti-cracking strength, compressive strength and tensile strength compared with the comparative examples 1-3, and by modifying the steel fibers and quartz sand, the pore structure of the concrete is effectively improved, the compactness, toughness and strength of the concrete are improved, the performance of the concrete is effectively improved, and the service life of the concrete is improved.

[0062] The above only describes the preferred embodiments of the present application and is not intended to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A type of ultra-high performance concrete, characterized in that, The raw materials include the following parts by weight: 260-280 parts cement, 120-160 parts modified quartz sand powder, 8-15 parts modified steel fiber, 20-26 parts fly ash, 7-12 parts polycarboxylate superplasticizer, 16-24 parts EVA emulsion, 4-7 parts alkali-resistant glass fiber, and 140-180 parts water. The modified steel fiber is prepared as follows: steel fibers are soaked in potassium hydroxide solution and then dried. The dried steel fibers are added to calcium hydroxide slurry, and potassium carbonate is added for a first stirring reaction. Then, a mixed solution of nano-SiO2 and coupling agent is added for a second stirring reaction. After filtration and drying, the modified steel fiber is obtained. The first stirring reaction conditions are: stirring for 8-10 seconds with an interval of 8-10 seconds at a temperature of 65-80℃ and a stirring speed of 45-60 r / min, with a total stirring time of 6-10 min. Then, the stirring speed is increased to 200-300 r / min and the reaction is carried out for 1-3 h. The second stirring reaction conditions are: stirring for 30-60 min at a temperature of 50-70℃ and a stirring speed of 400-600 r / min. The modified quartz sand powder is prepared by taking quartz sand powder, graphene oxide, and polyethylene glycol solution in a mass ratio of 3-5:1-3:6-8. Graphene oxide is added to polyethylene glycol solution and stirred and mixed. Quartz sand powder is then added and stirred and mixed. The mixture is then ultrasonically dispersed, filtered, and the filter residue is dried and pulverized to obtain modified quartz sand powder.

2. The ultra-high performance concrete according to claim 1, characterized in that, The mass ratio of the steel fiber, calcium hydroxide slurry, potassium carbonate, and the mixed solution is 4-5:2-4:5-7:3-6; the concentration of the potassium hydroxide solution is 12-16 wt%; the concentration of the calcium hydroxide slurry is 2.0-5.0 wt%; and the coupling agent is one or a combination of two or more of the following: silane coupling agent, titanate coupling agent, or aluminate coupling agent.

3. The ultra-high performance concrete according to claim 1, characterized in that, The preparation process of the mixed solution of nano-SiO2 and coupling agent is as follows: nano-SiO2, coupling agent and water are taken in a mass ratio of 1-2:0.1-0.3:2-3. Nano-SiO2 is added to water and stirred and mixed. Then the coupling agent is added and stirred and mixed to obtain the mixed solution of nano-SiO2 and coupling agent.

4. The method for preparing ultra-high performance concrete according to any one of claims 1-3, characterized in that, Includes the following steps: Cement, modified quartz sand powder, modified steel fiber, fly ash, and alkali-resistant glass fiber are mixed evenly according to the specified ratio. Then, polycarboxylate superplasticizer, EVA emulsion, and water are added and mixed evenly before being poured into a mold and cast to form ultra-high performance concrete.

5. The method for preparing ultra-high performance concrete according to claim 4, characterized in that, The concentration of the EVA emulsion is 50-60 wt%.