CN109678433B - Ultrahigh-strength self-compacting micro-expansion steel pipe concrete and preparation method thereof - Google Patents
Ultrahigh-strength self-compacting micro-expansion steel pipe concrete and preparation method thereof Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
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Abstract
The invention discloses ultrahigh-strength self-compacting micro-expansion steel pipe concrete and a preparation method thereof. The composition comprises the following components in parts by weight: 580-680 parts of cement, 30-60 parts of fly ash microbeads, 25-50 parts of silica fume, 20-35 parts of an expanding agent, 700-750 parts of machine-made sand, 800-1050 parts of broken stone, 0.4-1.2 parts of a shrinkage reduction functional material, 3.5-7 parts of an additive, 120-160 parts of water and 4-5.5 parts of copper-plated short and fine steel fibers. The invention adopts machine-made sand with high stone powder content to replace natural river sand, takes stone powder as an inert admixture, adopts high-activity fly ash microbeads and silica fume, and utilizes the ball effect and the micro-aggregate effect to enhance the workability and the compactness of concrete and improve the homogeneity of the concrete. The novel expanding agent is prepared from the fly ash and the phosphogypsum, so that the strength is improved, and the air content is further reduced and the compactness is improved by using the additive. The machine-made sand concrete with high stone powder content has excellent working performance, mechanical property, volume stability and crack resistance.
Description
Technical Field
The invention belongs to the technical field of materials, and particularly relates to ultrahigh-strength self-compacting micro-expansion steel pipe concrete and a preparation method thereof.
Background
At present, China is a positive value to greatly promote the western construction period, and a large number of bridges with good quality, excellent mechanical properties, economic manufacturing cost and easy construction are urgently needed in western regions in consideration of natural conditions of the western regions in high chongshan mountains and high mountains. Generally, natural river sand is needed for preparing high-performance fair-faced concrete for bridges, however, river sand resources in western regions are deficient, and in order to protect river beds, local abundant machine-made sand resources are used for replacing river sand.
The machine-made sand is formed by artificial crushing, some fine stone powder and mud powder with the grain diameter less than or equal to 0.75 mu m are inevitably introduced in the production process, the adsorption capacity of the additive to the concrete prepared by the machine-made sand is large, the working performance and the homogeneity of the concrete are poor, the concrete is easy to have bottom scraping and bleeding, the shrinkage of the concrete is obviously increased, and the concrete is easy to crack in the early stage, so that the national standard JTG TF50-2011 limits the stone powder content in the machine-made sand for the concrete. However, the fine powder is removed by adopting washing machine-made sand, which causes serious environmental pollution and increases the cost of concrete raw materials and the construction cost. Therefore, higher requirements are provided for the workability and the compressive strength of the concrete, the concrete is restrained by an external steel pipe after being hardened, and if the concrete is greatly contracted, the concrete can be separated, so that stress concentration is caused.
Disclosure of Invention
The invention aims to provide the ultrahigh-strength self-compacting micro-expansion steel pipe concrete prepared by utilizing the machine-made sand with high fine powder content and the preparation method thereof, and the ultrahigh-strength self-compacting micro-expansion steel pipe concrete has excellent working performance, mechanical property, volume stability and crack resistance, has good pumping property, is easy to construct, has lower control requirement on the stone powder content and has important practical application value.
In order to achieve the purpose, the technical scheme is as follows:
the ultrahigh-strength self-compacting micro-expansion steel pipe concrete comprises the following components in parts by weight:
580-680 parts of cement, 30-60 parts of fly ash microbeads, 25-50 parts of silica fume, 20-35 parts of an expanding agent, 700-750 parts of machine-made sand, 800-1050 parts of broken stone, 0.4-1.2 parts of a shrinkage reduction functional material, 3.5-7 parts of an additive, 120-160 parts of water and 4-5.5 parts of copper-plated short and fine steel fibers.
According to the scheme, the fineness modulus of the machine-made sand is 2.3-3.0, the crushing value is less than or equal to 7%, the methylene blue value is less than 1.5, the mass content of fine powder in the machine-made sand is 8-20%, and the particle size of the fine powder is less than or equal to 0.75 mu m.
According to the scheme, the specific surface area of the fly ash micro-beads is more than or equal to 1300m2The activity index is more than or equal to 101 percent, the water demand ratio is less than or equal to 95 percent, and the crystal structure is amorphous.
According to the scheme, the activity index of the silica fume is more than or equal to 105 percent, and the SiO content is2The mass content is more than or equal to 90 percent, the ignition loss is less than or equal to 5 percent, and the specific surface area is more than or equal to 16000m2/kg。
According to the scheme, the broken stone is limestone broken stone or basalt broken stone, the continuous gradation is 5-20, the mass content of needle-shaped particles is less than or equal to 8%, and the crushing value is less than or equal to 10%.
According to the scheme, the expanding agent is prepared in the following way:
1) weighing and uniformly mixing the fly ash, the phosphogypsum and the solid sulfur ash according to the mass ratio of (5) (2.5-4.5) to (1.5-2.5);
2) adding water according to the water-solid ratio of 5 (1-2) and stirring for 3 min;
3) and curing the mixed raw materials by steam, sieving the raw materials by a 150-mesh sieve, drying, cooling and sealing to obtain the expanding agent.
According to the scheme, the shrinkage-reducing functional material is prepared in the following mode:
1) mixing dipropylene glycol monobutyl ether, succinic anhydride and maleic anhydride according to the molar ratio of 1 (1.5-2) to 1.2-1.5, reacting for 4-6 h at 80-120 ℃, and condensing to obtain a polymer macromonomer A with a shrinkage reducing function;
2) grinding and homogenizing 50-70% of magnesium slag and 30-50% of dolomite, and pre-calcining at 700-900 ℃ for 50-80 min to obtain a prefabricated mixed powder; mixing the prefabricated mixed powder with fluorite powder according to a mass ratio of 5 (1.5-3), hydrolyzing for 20-30 min at 80-120 ℃, filtering, purifying, drying, calcining for 50-60 min at a low temperature of 500-600 ℃, naturally cooling, and grinding until the screen residue of a square hole with the diameter of 60 mu m is less than or equal to 5% to obtain an expansion component B; wherein the MgO and the CaO account for 60-70% and 30-40% respectively by mass;
3) grinding 30-40% of sodium montmorillonite and 60-70% of kaolin by mass percentage, homogenizing, and controlling the 60 mu m square hole screen residue to be less than or equal to 5% to obtain a layered silicate mineral C with water retention property;
4) heating a polymer macromonomer A to 70-80 ℃, then respectively adding an expansion component B and a phyllosilicate mineral C, uniformly stirring, keeping the temperature for 20-30 min to obtain a polymer emulsion, and then adding Na (OH)2And adjusting the pH value of the solution to be neutral, finally drying at 50-60 ℃, grinding and sieving with a 200-mesh sieve to obtain the material with the function of reducing shrinkage.
According to the scheme, the additive is a polycarboxylic acid high-efficiency water reducing agent and is prepared in the following mode:
1) putting methacrylic acid, polyethylene glycol monomethyl ether and hydroquinone into a three-neck flask according to the molar ratio of (3-5): 2-3.5): 1, stirring and heating to 60-75 ℃ under the action of a catalyst I, reacting for 6-8 h, keeping the temperature for 0.5-1.5 h, adjusting the pH to be neutral by using sodium hydroxide, and separating to obtain methoxy polyethylene oxide methacrylate; wherein the catalyst I is a p-toluenesulfonic acid solution with the mass concentration of 1-2%, and the addition amount of the catalyst I is 5-10% of the mass of methacrylic acid;
2) mixing ethylene oxide and propylene oxide at a molar ratio of (1-3) to 1 at 100-150 ℃, carrying out random copolymerization by using potassium hydroxide as a basic catalyst II, and controlling the polymerization degree of the copolymer within the range of 80-90 to obtain EPE block copolyether;
3) and (2) mixing the methoxy polyethylene oxide methacrylate, the EPE block copolyether and the chain transfer agent according to the molar ratio of (2.5-4) to (6-9) to 1, stirring, introducing nitrogen, adding a small amount of deionized water, heating to 75-90 ℃, reacting for 2.5-4 h, and adjusting the pH to 6-7 by using a sodium hydroxide solution to obtain the polycarboxylic acid type high-efficiency water reducing agent.
According to the scheme, the two ends of the copper-plated short and thin steel fiber are not provided with end hooks, the short fiber is round and thin, the breaking elongation is 14%, and the tensile strength is 1620 MPa.
The preparation method of the ultrahigh-strength self-compacting micro-expansion concrete filled steel tube comprises the following steps:
1) the machine-made sand and the crushed stone are mixed uniformly in a dry mode in advance according to the proportion, and then the cement, the fly ash microbeads, the silica fume and the expanding agent are added to be mixed uniformly in a continuous dry mode;
2) mixing the additive and water, slowly pouring 70% of the mixture into a stirring pot, simultaneously starting stirring for 1-2 min, adding the copper-plated short and thin steel fibers, and slowly adding the rest additive and water to obtain a mixed concrete mixture; pouring the mixed mixture into a mold, and maintaining to obtain the ultrahigh-strength self-compacting micro-expansion steel pipe concrete.
The invention adopts machine-made sand with high fine powder content to replace river sand to prepare the ultra-high strength steel pipe concrete, when the fine powder (stone powder and mud powder) content in the machine-made sand is higher, the obtained concrete has large adsorption capacity to additives, the working performance and the homogeneity of the concrete are poor, and the concrete is easy to have the problems of bottom scraping and bleeding; the superfine particle size of the concrete can improve the compactness of the concrete, improve the interface between cement slurry and coarse aggregate in the concrete, reduce harmful capillary pores and improve the strength and corrosion resistance of the concrete; the silica fume has the functions of improving cohesiveness and retaining water, and avoids the segregation and bleeding phenomena of the ultrahigh-strength steel pipe concrete prepared from the machine-made sand with high fine powder content; the compounding of the active fly ash micro-beads and the silica fume can also effectively improve an interface transition region in the concrete gelled slurry body, generate C-S-H gel with lower Ca/Si, and improve the capability of resisting external erosion, thereby improving the durability of the concrete, improving the fluidity and cohesiveness of the machine-made sand ultrahigh-strength steel pipe concrete, and being beneficial to pumping construction.
Concrete prepared by adopting the high-fine-powder-content machine-made sand has large shrinkage and is easy to crack in the early stage, the concrete is restrained by an external steel pipe after being hardened, and if the concrete shrinks greatly, the concrete and the steel pipe are separated to form stress concentration, so that the mechanical property of the structure is influenced, and the service life of a bridge is shortened. The expanding agent prepared by the invention can generate an expansive product when hydrated in concrete, and fills capillary pores and defects in concrete gelled slurry, so that the volume stability of the concrete is improved; meanwhile, the doped saturated pre-wet shale ceramsite can slowly release water in the concrete strength development process, so that the drying shrinkage and self-shrinkage caused by the reduction of the internal humidity of the concrete are reduced, and the early cracking sensitivity of the concrete is reduced; the admixture also has the shrinkage reducing function, and can obviously reduce the tension of capillary pores in the concrete gelled slurry so as to effectively inhibit the shrinkage of the concrete; the effect is synergistic effect, and the anti-cracking performance of the obtained concrete can be effectively improved.
The polymer macromonomer with the shrinkage reducing function in the shrinkage reducing functional material adopted by the invention can reduce the surface tension of capillary liquid in the concrete, reduce the compressive stress generated by water evaporation, reduce the concrete shrinkage, greatly reduce the free water amount of the capillary wall capable of carrying out migration evaporation, mostly convert the free water into bound water, and reduce the dependence of expansion components on external maintenance water. The sodium montmorillonite and kaolin phyllosilicate mineral have a water retention function at the early stage, and water begins to be released under the action of negative pressure along with the consumption of free water in the concrete, so that a stable humidity field with higher relative humidity is provided, the humidity field can provide guarantee for MgO and CaO expansion components, and the MgO and CaO expansion components have the effect of continuously compensating shrinkage on the concrete, so that the volume stability and the anti-cracking performance of the high-stone-powder-content machine-made sand concrete are improved. Meanwhile, the expansion product can further block capillary channels, reduce the porosity of the concrete, enable the concrete to be more compact and prevent external erosive ions from entering the interior of the concrete.
During the super high strength steel pipe concrete pump sending process, concrete and steel pipe inner wall friction, under the effect of shear stress, easy segregation, and require the concrete to have great mobility, avoid stifled pipe, it is good to protect the water retention, and self-compaction degree is high, and early strength rises fast. The additive can improve the dispersion degree of cement particles and improve the cementation property of cement: with the progress of cement hydration reaction, the polyether side chain gradually generates hydrolysis reaction from the main chain in the strong alkaline environment of cement, and the fluidity retention capacity of concrete is improved.
The machine-made sand self-compacting concrete is usually small in water gel, the brittleness of the machine-made sand self-compacting concrete continuously increases along with the increase of strength, and when the machine-made sand self-compacting concrete is close to the ultimate bearing capacity, the brittle failure of the high-strength concrete is caused by the propagation and the expansion of microcracks in the high-strength concrete. The invention adopts the added copper-plated short and thin steel fiber, and can effectively prevent the expansion of internal microcracks and the occurrence and development of macroscopic cracks by virtue of the disorderly distribution of the copper-plated short and thin steel fiber in the matrix concrete, restrain the transverse deformation of the concrete when being pressed, delay the damage process and improve the deformation resistance and the compressive strength of the high-strength concrete to a certain extent.
Compared with the prior art, the invention has the beneficial effects that:
the invention adopts the machine-made sand with high fine powder content to prepare the ultra-high strength micro-expansion steel pipe concrete, and preferably selects the active fly ash micro-beads with high activity and mineral water reduction and the silica fume with the functions of water retention and viscosity regulation as mineral admixture, thereby effectively improving the segregation and bleeding phenomena of the machine-made sand with high fine powder content to prepare the ultra-high strength micro-expansion steel pipe concrete, improving the cohesiveness of slurry, improving the wrapping property of cementing materials to aggregates, increasing the fluidity of the concrete, greatly improving the pumpability of the concrete and being easy to construct.
The high-performance admixture developed by the invention can obviously improve the working performance and the fluidity retention capacity of concrete, uniformly disperse gelled particles in the concrete, reduce the cement consumption and the water consumption of single-side concrete, and improve the compactness and the strength of the concrete; the alkyl polyether shrinkage reducing group on the water reducing agent can reduce the surface tension of a pore solution in a concrete slurry body, reduce the shrinkage of concrete, enable the prepared steel pipe concrete to have self-compaction performance, and improve the construction speed and the engineering quality of the ultrahigh-strength micro-expansion steel pipe concrete engineering.
The invention relates to a preparation technology of ultra-high strength micro-expansion steel pipe concrete, which applies a compensation shrinkage principle and a concrete internal curing technology to the preparation of high fine powder content machine-made sand self-compaction ultra-high strength micro-expansion steel pipe concrete, and further aims at the problems of large shrinkage, early cracking and the like of the concrete prepared by high fine powder content machine-made sand on the basis of improving the cohesiveness of the concrete by adopting silica fume and fly ash micro-beads and avoiding segregation and layering in the pumping process; and preferably, the high-strength porous lightweight aggregate can slowly release water in the early strength development process of the concrete, reduce drying shrinkage and self-shrinkage caused by the reduction of the internal humidity of the concrete, reduce the early cracking sensitivity of the concrete, and realize the improvement of the cracking resistance of the ultra-high-strength micro-expansion steel pipe concrete from the early stage to the later stage.
Aiming at the characteristics of low water-cement ratio, high brittleness and easy generation of microcracks of high-performance concrete, the invention selects the copper-plated short and thin steel fibers by comparing different steel fibers through a large number of experiments. The fiber has no end hook at two ends and short length, can be disorderly arranged along with slurry in concrete, and is not easy to be mutually overlapped to form a shed frame structure, thereby causing stress concentration. The copper-plated short and fine steel fibers have good dispersibility, have low influence on the working performance of concrete, are randomly arranged inside and can exert certain constraint on each direction of a concrete structure, and the risk of early hydration, temperature rise and cracking of the concrete is reduced.
Detailed Description
The following examples further illustrate the technical solutions of the present invention, but should not be construed as limiting the scope of the present invention.
The cement adopts Nychium omeiense P.O 42.5 ordinary portland cement; the silica fume is available from Wydomngling technologies, Inc. and has an activity index of 105% and SiO292 percent of mass content, 4.5 percent of ignition loss and 17000m of specific surface area2Per kg; the fly ash micro-beads are provided by Technical Co Ltd for building new materials by Tianjin, and the specific surface area is 1470m2Per kg, the activity index is 103 percent, the water demand ratio is 92 percent, and the crystal state is not realized; the fineness modulus of the machine-made sand is 2.74, the crushing value is 6.7%, the mass content of the fine powder is 14.3%, and the methylene blue value is 1.4; the crushed stone is 5-20 mm basalt crushed stone with continuous gradation, the mass content of needle-shaped particles is 7%, and the crushing value is 6%; the elongation at break of the copper-plated short and fine steel fiber is 14 percent, and the tensile strength is 1620 MPa; the water is ordinary tap water.
Examples 1 to 2
A method for preparing ultra-high strength micro-expansion steel tube concrete (C30-C40) by using machine-made sand with high fine powder content comprises the following steps:
1) weighing the raw materials according to the mixture ratio shown in the table 1-1;
2) pouring the weighed machine-made sand and crushed stone into a stirring pot according to the proportion, dry-mixing for 1min, uniformly mixing, adding cement, fly ash microbeads, silica fume, an expanding agent and a shrinkage reduction functional material, continuously dry-mixing for 1.5min, mixing an additive and water, slowly pouring 70% of the mixture into the stirring pot, simultaneously starting stirring for 2min, adding the weighed steel fibers, slowly adding the rest water and the additive, continuously stirring for 1min to obtain a uniform mixture, pouring the uniform mixture into a mold, and carrying out standard maintenance after 1d of mold removal to obtain the ultrahigh-strength micro-expansion steel pipe concrete prepared from the high-fine powder content machine-made sand.
3) The preparation method of the shrinkage-reducing functional material described in the embodiments 1-2 comprises the following steps: 1) mixing dipropylene glycol monobutyl ether, succinic anhydride and maleic anhydride according to the molar ratio of 1:1.5:1.2, reacting for 6 hours at 100 ℃, and condensing to obtain a polymer macromonomer A with a shrinkage reducing function; 2) grinding 73% of magnesium slag and 27% of dolomite in percentage by mass, homogenizing, pre-calcining at 900 ℃ for 65min, mixing the prefabricated mixed powder with fluorite powder according to the mass ratio of 5:2, then hydrolyzing at 80 ℃ for 30min, filtering, purifying, drying, then calcining at 550 ℃ for 60min, naturally cooling, grinding until the residue of a square hole with 60 mu m is less than or equal to 5%, and obtaining an expansion component B, wherein MgO and CaO account for 60% and 40% in percentage by mass respectively; 3) grinding 34% of sodium montmorillonite and 66% of kaolin, homogenizing, and controlling the 60-micron square-hole screen residue to be less than or equal to 5% to obtain a layered silicate mineral C with water retention property; 4) weighing the components prepared in the steps 1) to 3) according to the following mass percentage, wherein the polymer macromonomer A42%, the expansion component B30% and the phyllosilicate mineral C28% are heated to 70 ℃, then the expansion component B and the phyllosilicate mineral C are respectively added, the polymer macromonomer A is uniformly stirred and the temperature is kept for 25min to obtain polymer emulsion, and Na (OH) is added2And regulating the pH value of the solution to be neutral, drying at 60 ℃, grinding and sieving by a 200-mesh sieve to obtain the internal curing shrinkage-reducing functional material.
4) The preparation method of the admixture described in the embodiment 1-2 comprises the following steps: 1) adding methacrylic acid, polyethylene glycol monomethyl ether and hydroquinone into a three-neck flask according to the molar ratio of 4.5:2:1, stirring and heating to 65 ℃ under the action of a catalyst I, reacting for 8 hours, keeping the temperature for 1.5 hours, separating liquid after treating with sodium hydroxide until the solution is neutral, wherein the catalyst I is a p-toluenesulfonic acid solution with the mass concentration of 1%, and the addition amount of the catalyst I is 7% of the mass of the methacrylic acid, so as to obtain the methoxy polyethylene oxide methacrylate. Carrying out random copolymerization on ethylene oxide and propylene oxide at a molar ratio of 2.5:1 at 130 ℃ by taking potassium hydroxide as an alkaline catalyst II, and controlling the copolymer to be within the range of 80-90 polymerization degrees to obtain a polycarboxylate superplasticizer molecular side chain monomer (EPE block copolyether); mixing a polycarboxylate superplasticizer molecular main chain, a polycarboxylate superplasticizer molecular side chain monomer (EPE block copolyether) and a chain transfer agent in a molar ratio of 2:9:1 in a four-neck flask, stirring, introducing nitrogen, adding a small amount of deionized water, heating to 85 ℃, and reacting for 3 hours. And after the reaction is finished, adjusting the pH value to 6 by using a 40% sodium hydroxide solution to obtain the polycarboxylic acid high-efficiency water reducing agent.
5) The preparation method of the expanding agent described in the embodiments 1-2 comprises the following steps: 1) weighing and uniformly mixing the fly ash, the phosphogypsum and the solid sulfur ash according to the mass ratio of 5:3: 1.5. 2) Adding water according to the water-solid ratio of 5:1, and stirring for 3 min. 3) And curing the mixed raw materials by steam, sieving the raw materials by a 150-mesh sieve, drying, cooling and sealing to obtain the expanding agent.
The performance test results of the ultra-high strength micro-expansion steel pipe concrete obtained in examples 1-2 are shown in tables 1-2.
TABLE 1-1 concrete mix proportion (kg/m) of ultra-high strength micro-expansion steel tube described in examples 1 to 23)
TABLE 1-2 Properties of ultra-high Strength micro-expansive Steel tube concrete described in examples 1-2
Examples 3 to 4
A method for preparing ultra-high strength micro-expansion steel tube concrete (C120-C140) by using machine-made sand with high fine powder content comprises the following steps:
1) weighing the raw materials according to the mixture ratio shown in the table 2-1;
2) pouring the weighed machine-made sand and crushed stone into a stirring pot according to the proportion, dry-mixing for 1min, then adding the weighed cement, fly ash microbeads, silica fume, an expanding agent and a shrinkage reduction material, continuously dry-mixing for 1min, then mixing an additive and water, slowly pouring the mixture into the stirring pot, simultaneously starting stirring, wherein the duration time is 2min, adding the weighed steel fibers, slowly adding the rest water and the additive, continuously stirring for 1min, obtaining a uniform concrete mixture, finally pouring into a mold, and carrying out standard maintenance after 1d of mold removal, thus obtaining the self-compacting anti-cracking fair-faced concrete prepared from the high-fine powder content machine-made sand. The properties of the self-compacting anti-crack fair-faced concrete obtained in examples 3 to 4 are shown in Table 2-2.
3) The preparation method of the shrinkage-reducing functional material described in the embodiments 1-2 comprises the following steps: 1) mixing dipropylene glycol monobutyl ether, succinic anhydride and maleic anhydride in a molar ratio of 1:2:1.4, reacting for 5 hours at 120 ℃, and condensing to obtain a polymer macromonomer A with a shrinkage reducing function; 2) grinding and homogenizing 55 mass percent of magnesium slag and 45 mass percent of dolomite, pre-calcining at 900 ℃ for 60min, mixing the prefabricated mixed powder with fluorite powder according to the mass ratio of 5:2, then hydrolyzing at 110 ℃ for 30min, filtering, purifying, drying, then calcining at 550 ℃ for 55min, naturally cooling, grinding until the residue of a square hole with 60 mu m is less than or equal to 5 percent, and obtaining an expansion component B, wherein MgO and CaO account for 66 percent and 34 percent respectively; 3) grinding and homogenizing 40% of sodium montmorillonite and 60% of kaolin respectively in percentage by mass, and controlling the 60 mu m square hole screen residue to be less than or equal to 5% to obtain a layered silicate mineral C with water retention property; 4) weighing the components prepared in the steps 1) to 3) according to the following mass percentage, wherein the polymer macromonomer A48%, the expansion component B32% and the layered silicate mineral C20% are heated to 80 ℃, then the expansion component B and the layered silicate mineral C are respectively added, the polymer macromonomer A is uniformly stirred and the temperature is kept for 25min to obtain polymer emulsion, and Na (OH) is added2And regulating the pH value of the solution to be neutral, drying at 60 ℃, grinding and sieving by a 200-mesh sieve to obtain the internal curing shrinkage-reducing functional material.
4) The preparation method of the admixture described in the embodiment 1-2 comprises the following steps: 1) adding methacrylic acid, polyethylene glycol monomethyl ether and hydroquinone into a three-neck flask according to the molar ratio of 4:3:1, stirring and heating to 75 ℃ under the action of a catalyst I, reacting for 6 hours, preserving heat for 1.5 hours, separating liquid after treating with sodium hydroxide until the solution is neutral, wherein the catalyst I is a p-toluenesulfonic acid solution with the mass concentration of 1%, and the addition amount of the catalyst I is 8% of the mass of the methacrylic acid, so as to obtain the methoxy polyethylene oxide methacrylate. Carrying out random copolymerization on ethylene oxide and propylene oxide at a molar ratio of 2.5:1 at 120 ℃ by taking potassium hydroxide as an alkaline catalyst II, and controlling the copolymer to be within the range of 80-90 polymerization degrees to obtain a polycarboxylate superplasticizer molecular side chain monomer (EPE block copolyether); mixing a polycarboxylate superplasticizer molecular main chain, a polycarboxylate superplasticizer molecular side chain monomer (EPE block copolyether) and a chain transfer agent in a molar ratio of 3.5:8:1 in a four-neck flask, stirring, introducing nitrogen, adding a small amount of deionized water, heating to 80 ℃, and reacting for 2.5 hours. And after the reaction is finished, adjusting the pH value to 6 by using a 40% sodium hydroxide solution to obtain the polycarboxylic acid high-efficiency water reducing agent.
5) The preparation method of the expanding agent described in embodiments 3 to 4 includes the following steps: 1) weighing and uniformly mixing the fly ash, the phosphogypsum and the solid sulfur ash according to the mass ratio of 5:3: 2. 2) Adding water according to the water-solid ratio of 5:2, and stirring for 3 min. 3) And curing the mixed raw materials by steam, sieving the raw materials by a 150-mesh sieve, drying, cooling and sealing to obtain the expanding agent.
Table 2-1 ultra-high strength self-compacting micro-expansive steel tube concrete mix proportion (kg/m) described in examples 3-43)
Table 2-2 properties of ultra-high strength self-compacting micro-expansive steel tube concrete obtained in examples 3-4
The results show that different strength grades (C100-C140) can be designed according to actual engineering requirements, and the ultrahigh-strength self-compacting micro-expansion steel tube concrete prepared by the invention by utilizing the machine-made sand with high fine powder content contains gasThe amount is less than or equal to 2.0 percent, the slump is more than 240mm, the expansion is more than 600mm, the loss of the slump and the expansion after 2 hours is less than 15mm, the good workability is realized, the pumping is facilitated, the segregation and delamination phenomena can be better avoided, and the 90d shrinkage is less than or equal to 2 multiplied by 10-4The anti-cracking grade is grade V; the self-compacting anti-cracking concrete bridge has excellent self-compacting anti-cracking performance, can improve the construction speed and the construction quality of concrete engineering, meets the requirement of the design quality of the ultra-high strength steel pipe concrete bridge, has wide raw material sources, low control requirement on the content of machine-made sand powder and simple preparation process.
Claims (7)
1. The ultrahigh-strength self-compacting micro-expansion concrete filled steel tube is characterized by comprising the following components in parts by weight:
580-680 parts of cement, 30-60 parts of fly ash microbeads, 25-50 parts of silica fume, 20-35 parts of an expanding agent, 700-750 parts of machine-made sand, 800-1050 parts of broken stone, 0.4-1.2 parts of a shrinkage reduction functional material, 3.5-7 parts of an additive, 120-160 parts of water and 4-5.5 parts of copper-plated short and fine steel fibers;
the swelling agent is prepared in the following way:
1) weighing and uniformly mixing the fly ash, the phosphogypsum and the solid sulfur ash according to the mass ratio of (5) (2.5-4.5) to (1.5-2.5);
2) adding water according to the water-solid ratio of 5 (1-2) and stirring for 3 min;
3) curing the mixed raw materials by steam, sieving the raw materials by a 150-mesh sieve, drying, cooling and sealing to obtain the expanding agent;
the shrinkage-reducing functional material is prepared in the following way:
1) mixing dipropylene glycol monobutyl ether, succinic anhydride and maleic anhydride according to the molar ratio of 1 (1.5-2) to 1.2-1.5, reacting for 4-6 h at 80-120 ℃, and condensing to obtain a polymer macromonomer A with a shrinkage reducing function;
2) grinding and homogenizing 50-70% of magnesium slag and 30-50% of dolomite, and pre-calcining at 700-900 ℃ for 50-80 min to obtain a prefabricated mixed powder; mixing the prefabricated mixed powder with fluorite powder according to a mass ratio of 5 (1.5-3), hydrolyzing for 20-30 min at 80-120 ℃, filtering, purifying, drying, calcining for 50-60 min at a low temperature of 500-600 ℃, naturally cooling, and grinding until the screen residue of a square hole with the diameter of 60 mu m is less than or equal to 5% to obtain an expansion component B; wherein the MgO and the CaO account for 60-70% and 30-40% respectively by mass;
3) grinding 30-40% of sodium montmorillonite and 60-70% of kaolin by mass percentage, homogenizing, and controlling the 60 mu m square hole screen residue to be less than or equal to 5% to obtain a layered silicate mineral C with water retention property;
4) heating a polymer macromonomer A to 70-80 ℃, then respectively adding an expansion component B and a layered silicate mineral C, uniformly stirring, keeping the temperature for 20-30 min to obtain a polymer emulsion, adding a NaOH solution to adjust the pH value to be neutral, finally drying at 50-60 ℃, grinding, and sieving with a 200-mesh sieve to obtain a shrinkage-reducing functional material;
the additive is a polycarboxylic acid water reducer and is prepared in the following way:
1) putting methacrylic acid, polyethylene glycol monomethyl ether and hydroquinone into a three-neck flask according to the molar ratio of (3-5): 2-3.5): 1, stirring and heating to 60-75 ℃ under the action of a catalyst I, reacting for 6-8 h, keeping the temperature for 0.5-1.5 h, adjusting the pH to be neutral by using sodium hydroxide, and separating to obtain methoxy polyethylene oxide methacrylate; wherein the catalyst I is a p-toluenesulfonic acid solution with the mass concentration of 1-2%, and the addition amount of the catalyst I is 5-10% of the mass of methacrylic acid;
2) mixing ethylene oxide and propylene oxide at a molar ratio of (1-3) to 1 at 100-150 ℃, carrying out random copolymerization by using potassium hydroxide as a basic catalyst II, and controlling the polymerization degree of the copolymer within the range of 80-90 to obtain EPE block copolyether;
3) and (2) mixing the methoxy polyethylene oxide methacrylate, the EPE block copolyether and the chain transfer agent according to the molar ratio of (2.5-4) to (6-9) to 1, stirring, introducing nitrogen, adding a small amount of deionized water, heating to 75-90 ℃, reacting for 2.5-4 h, and adjusting the pH to 6-7 by using a sodium hydroxide solution to obtain the polycarboxylic acid water reducer.
2. The ultra-high strength self-compacting micro-expansion steel tube concrete as claimed in claim 1, wherein the fineness modulus of the machine-made sand is 2.3-3.0, the crushing value is less than or equal to 7%, the methylene blue value is less than 1.5, the mass content of fine powder in the machine-made sand is 8-20%, and the particle size of the fine powder is less than or equal to 0.75 μm.
3. The ultra-high strength self-compacting micro-expansion steel tube concrete as claimed in claim 1, characterized in that the specific surface area of the fly ash micro-beads is not less than 1300m2The activity index is more than or equal to 101 percent, the water demand ratio is less than or equal to 95 percent, and the crystal structure is amorphous.
4. The ultra-high strength self-compacting micro-expansion steel tube concrete according to claim 1, characterized in that the silica fume has an activity index of 105% or more and SiO2The mass content is more than or equal to 90 percent, the ignition loss is less than or equal to 5 percent, and the specific surface area is more than or equal to 16000m2/kg。
5. The ultra-high strength self-compacting micro-expansion steel tube concrete as claimed in claim 1, wherein the crushed stone is limestone crushed stone or basalt crushed stone, 5-20 mm continuous gradation, the mass content of needle-shaped flaky particles is less than or equal to 8%, and the crushing value is less than or equal to 10%.
6. The ultra-high strength self-compacting micro-expansion steel tube concrete according to claim 1, wherein the copper-plated short and thin steel fibers have no end hooks at both ends, are round and straight, have 14% elongation at break, and have 1620MPa tensile strength.
7. The method for preparing the ultra-high strength self-compacting micro-expansion steel tube concrete as recited in any one of claims 1-6, comprising the following steps:
1) the machine-made sand and the crushed stone are mixed uniformly in a dry mixing manner in advance according to the proportion, and then the cement, the fly ash micro-beads, the silica fume, the expanding agent and the shrinkage reducing functional material are added to be continuously mixed uniformly in a dry mixing manner;
2) mixing the additive and water, slowly pouring 70% of the mixture into a stirring pot, simultaneously starting stirring for 1-2 min, adding the copper-plated short and thin steel fibers, and slowly adding the rest additive and water to obtain a mixed concrete mixture;
3) pouring the mixed mixture into a mold, and maintaining to obtain the ultrahigh-strength self-compacting micro-expansion steel pipe concrete.
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| CN110937842B (en) * | 2019-12-18 | 2021-12-07 | 中建商品混凝土有限公司 | Additive for improving crack resistance and thixotropy of super high-rise pumped concrete |
| CN111116159B (en) * | 2020-01-02 | 2021-04-30 | 华南理工大学 | Phosphogypsum steel pipe concrete and preparation method thereof |
| CN111285648A (en) * | 2020-02-20 | 2020-06-16 | 中交上海三航科学研究院有限公司 | High-durability low-viscosity high-strength machine-made sand concrete, preparation method and application |
| CN111393105A (en) * | 2020-03-25 | 2020-07-10 | 中建西部建设西南有限公司 | Full-machine-made sand high-strength super-high-rise pumping concrete and production method and application thereof |
| CN112608122B (en) * | 2020-12-08 | 2022-08-19 | 广东省水利电力勘测设计研究院有限公司 | Micro-expansive epoxy emulsion modified self-compacting concrete for composite lining structure |
| CN113480272A (en) * | 2021-08-17 | 2021-10-08 | 雨发建设集团有限公司 | Self-curing micro-expansive ultrahigh-performance concrete and preparation method thereof |
| CN113773006B (en) * | 2021-09-16 | 2022-09-09 | 中交公路长大桥建设国家工程研究中心有限公司 | Ultrahigh-strength lightweight concrete and preparation method thereof |
| CN115321915A (en) * | 2022-08-25 | 2022-11-11 | 四川精益达工程检测有限责任公司 | C120 ultrahigh-strength compensation shrinkage self-compacting concrete filled steel tube and preparation method thereof |
| CN115504754B (en) * | 2022-10-18 | 2023-06-20 | 中铁大桥局集团有限公司 | Steel pipe concrete based on solid waste expansion and preparation method thereof |
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| CN101235138B (en) * | 2008-02-22 | 2010-12-08 | 江苏钟山化工有限公司 | Epoxy propane/epoxy ethane block copolyether and its preparation method and use |
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| CN107987222A (en) * | 2017-11-28 | 2018-05-04 | 合肥华福土工合成材料有限公司 | A kind of preparation method of high water reducing type solid high-performance polycarboxylate water-reducer |
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