CN115557751A - Low-temperature-rise anti-crack concrete and application thereof - Google Patents
Low-temperature-rise anti-crack concrete and application thereof Download PDFInfo
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- CN115557751A CN115557751A CN202211275246.0A CN202211275246A CN115557751A CN 115557751 A CN115557751 A CN 115557751A CN 202211275246 A CN202211275246 A CN 202211275246A CN 115557751 A CN115557751 A CN 115557751A
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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
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/34—Non-shrinking or non-cracking materials
- C04B2111/343—Crack resistant materials
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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
- C04B2201/52—High compression strength concretes, i.e. with a compression strength higher than about 55 N/mm2, e.g. reactive powder concrete [RPC]
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- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
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Abstract
The invention discloses low-temperature-rise anti-crack concrete and application thereof. The invention ensures the mechanical property of the concrete, and simultaneously reduces the adiabatic temperature rise of the concrete by doping the viscosity reducer and reducing the using amounts of cement and cementing materials; by adding the lightweight aggregate, the basalt fiber and the expanding agent, internal curing is provided for the concrete, and the shrinkage of the concrete is reduced and compensated; and the self-repairing capability of the concrete is improved by adding the microcapsules. The concrete prepared by the invention has excellent rheological property and crack resistance, can meet the construction requirement of high-strength concrete elevation pumping, can obviously reduce the emission of carbon dioxide, effectively reduces the maintenance cost of the concrete, and has good economic and social benefits.
Description
Technical Field
The invention belongs to the field of building materials, and particularly relates to low-temperature-rise anti-crack concrete and application thereof.
Background
The high-strength concrete has higher compactness and strength, so that the service life of a concrete structure can be obviously prolonged, and the high-strength concrete can be widely applied to high-rise structures and severe environments. However, compared with common concrete, the high-strength concrete has high consumption of cementing materials and low water-cement ratio, so that the hydration heat of the concrete is high, the shrinkage deformation is large, and the cracking risk is increased. High strength concrete, once cracked, results in a decrease in the impermeability of the concrete, and as the deterioration of the concrete continues to progress, the durability of the concrete also decreases.
At present, the main technical means for improving the crack resistance of the high-strength concrete are reducing the shrinkage and adiabatic temperature rise of the concrete. The method for reducing shrinkage mainly comprises an expanding agent, a high-water-absorption resin, a shrinkage reducing agent and the like, wherein the high-water-absorption resin and the shrinkage reducing agent have high cost and are not popularized and applied on a large scale, the expanding agent needs to consume water when being hydrated, but the high-strength concrete has low water-gel ratio, the effect of inhibiting the shrinkage of the high-strength concrete is still needed to be researched, and the prior art has a single means and is lack of systematic research. The method for reducing the adiabatic temperature rise mainly comprises the steps of reducing the cement consumption, adding a hydration heat inhibitor, adding a large-dosage mineral admixture and the like, wherein the hydration heat inhibitor is high in cost, and the cement consumption and the large-dosage mineral admixture can reduce the adiabatic temperature rise of the concrete, but the early strength of the concrete is lost, and the requirement on the quality stability of the admixture is high. Therefore, how to improve the anti-cracking performance of the concrete while maintaining the high strength of the concrete has important research value.
Disclosure of Invention
The invention provides low-temperature-rise anti-cracking concrete and application thereof, aiming at solving the problem that the existing concrete has excellent crack resistance, durability and pumping performance while being difficult to maintain high strength.
The technical scheme provided by the invention is as follows:
in a first aspect, the invention provides a low-temperature-rise crack-resistant concrete, which comprises the following components: 220kg/m cement 3 ～280kg/m 3 100kg/m of fly ash 3 ～150kg/m 3 50kg/m of viscosity reducer 3 ～100kg/m 3 Microcapsules of 5kg/m 3 ～15kg/m 3 400kg/m river sand 3 ～600kg/m 3 100kg/m of lightweight aggregate 3 ～200kg/m 3 1000kg/m of crushed stone 3 ～1200kg/m 3 1kg/m basalt fiber 3 ～5kg/m 3 4kg/m of water reducing agent 3 ～8kg/m 3 15kg/m of an expanding agent 3 ～30kg/m 3 120kg/m of water 3 ～150kg/m 3 。
In some embodiments provided by the invention, the water-to-gel ratio of the low-temperature-elevated anti-crack concrete is 0.30-0.31.
In some embodiments provided herein, the low temperature elevated crack resistant concrete has a sand fraction of 0.25 to 0.28.
In some embodiments provided herein, the viscosity reducer comprises, by weight (0.01-0.03): (0.2-0.3): (0.1-0.2) silica fume, microbeads, superfine mineral powder and limestone powder (0.4-0.7).
In some embodiments provided herein, the viscosity reducer has a specific surface area of 1200kg/m or more 3 The average grain diameter is 2-6 μm, the viscosity ratio is more than or equal to 60 percent, and the fluidity ratio is more than or equal to 105 percent.
In some embodiments provided herein, the weight ratio of the viscosity reducer in the low temperature elevated anti-crack concrete is between 3.5% and 4.5%.
In some embodiments provided by the present invention, the microcapsule wall material is glucose modified urea formaldehyde resin, the core material is aqueous polyurethane modified acrylate, the microcapsule is spherical particles, the particle size is normal distribution, the average particle size is 20 μm to 30 μm, and the content of the core material is 70wt% to 85wt%.
In some embodiments provided herein, the microcapsules are prepared by:
1) Adding the mixture of the waterborne polyurethane and the acrylate monomer into an emulsifier solution, uniformly mixing to obtain a mixed emulsion, adding sodium metabisulfite and ammonium persulfate, and reacting at the temperature of 70 ℃ or above to obtain a waterborne polyurethane modified acrylate core material emulsion;
2) Uniformly mixing urea and formaldehyde in an aqueous solution, adjusting the pH value to 7-9, adding glucose, reacting at the temperature of 60 ℃ and above to obtain a glucose modified urea-formaldehyde resin prepolymer, adding a waterborne polyurethane modified acrylate core material emulsion into the glucose modified urea-formaldehyde resin prepolymer, adjusting the pH value to 3 +/-0.5, adding a catalyst, adding resorcinol after reaction, continuing the reaction, and purifying to obtain the microcapsule of the waterborne polyurethane modified acrylate wrapped by the glucose modified urea-formaldehyde resin.
In some embodiments provided herein, the catalyst is NH 4 Cl, urea and formaldehyde in a molar ratio of 1.
In some embodiments provided herein, the acrylate monomer mixture comprises acrylic acid, hydroxypropyl acrylate, and stearyl acrylate in a weight ratio of 3.
In some embodiments provided herein, the emulsifier is a complex emulsifier of sodium dodecylbenzenesulfonate and tween-80 in a weight ratio of 1.
In some embodiments of the present invention, the lightweight aggregate is ceramic sand or pumice, which is pre-wetted before use, has a particle size of 1mm to 5mm, and a bulk density of 700kg/m 3 ～900kg/m 3 The cylinder pressure strength is more than or equal to 7MPa, and the water absorption rate is more than or equal to 10 percent; the basalt fiber is formed by mixing long fibers and short fibers, the weight ratio of the long fibers to the short fibers is 7 3 (ii) a The water reducing agent is viscosity reduction type polycarboxylic acid high-performance reducerWater reducing rate of the water aqua is more than or equal to 30 percent; the expanding agent is MgO expanding agent, the MgO content is more than or equal to 90 percent, and the specific surface area is more than or equal to 20000m 2 /kg。
In a second aspect, the present invention provides the use of the low temperature elevated crack resistant concrete in the field of construction, in particular as high rise pump concrete.
In a third aspect, the invention provides a preparation method of low-temperature-rise anti-crack concrete, which comprises the following steps:
1) Weighing the following raw materials in proportion: 220kg/m cement 3 ～280kg/m 3 100kg/m of fly ash 3 ～150kg/m 3 50kg/m of viscosity reducer 3 ～100kg/m 3 Microcapsules 5kg/m 3 ～15kg/m 3 River sand 400kg/m 3 ～600kg/m 3 100kg/m of lightweight aggregate 3 ～200kg/m 3 1000kg/m of crushed stone 3 ～1200kg/m 3 1kg/m of basalt fiber 3 ～5kg/m 3 4kg/m of water reducing agent 3 ～8kg/m 3 15kg/m of an expanding agent 3 ～30kg/m 3 120kg/m of water 3 ～150kg/m 3 ；
2) Uniformly mixing the lightweight aggregate with 10 percent of the total water amount, and carrying out pre-wetting treatment;
3) Pouring cement, fly ash, a viscosity reducer, microcapsules and an expanding agent into a stirring pot, and uniformly stirring for 1-2 min to obtain mixed powder;
4) Adding the pre-wet lightweight aggregate into the mixed powder, stirring for 30s, adding river sand and broken stone, and stirring for 30s to obtain a mixed concrete dry mixed material;
5) And (3) uniformly mixing the water reducing agent and part of water, adding the mixture into the dry concrete mixture, stirring for more than 30s, pouring all the remaining water into a stirring pot, and continuously stirring for 2-3 min to obtain the low-temperature-rise anti-crack concrete.
Compared with the prior art, the invention has the following beneficial effects:
(1) On the premise of meeting the requirement of the mechanical property of the concrete, the viscosity reducer is doped, the dosage of the cement and the cementing material is reasonably controlled, the hydration heat release of the concrete is effectively delayed, and the adiabatic temperature rise and the temperature stress of the concrete are reduced, so that the cracking risk of the high-strength concrete is reduced.
(2) By combining the technical means of the lightweight aggregate, the expanding agent and the basalt fiber, the invention not only can play the role of internal curing, release water, compensate the drying and water loss of concrete and reduce the tension of capillary tubes, thereby reducing the shrinkage of the concrete, but also can provide water source for the expanding agent, generate an expansive product through hydration reaction and effectively compensate the shrinkage of the concrete. In addition, the basalt fiber has good environmental protection performance and mechanical property, can exert the effects of crack resistance and toughening in concrete, can reduce and refine cracks, and can improve the crack resistance of the concrete.
(3) The invention takes the microcapsule and the expanding agent as the main body of the repair material, can effectively repair physical damage on the surface of the concrete and improve the service life of the concrete. In addition, by doping the basalt fibers, the toughness of the concrete can be improved, the width of a concrete crack can be effectively controlled, and a good matrix environment is provided for self-repairing of the concrete.
(4) The viscosity reducer and the viscosity reduction type polycarboxylate superplasticizer are adopted, so that the accumulation state of concrete particles can be optimized, the plastic viscosity and the yield stress of high-strength concrete are obviously reduced, and the working performance and the pumping performance of the concrete are improved.
Detailed Description
For a better understanding of the present invention, the following examples are given to further illustrate the present invention, but the present invention is not limited to the following examples. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
The problem of concrete cracking generally exists, the characteristics, the mix proportion, the structure size, the environmental temperature, the environmental humidity and the like of raw materials of the concrete can influence the hydration heat release and the shrinkage of the high-strength concrete, and under the constraint condition, when the tensile strength of the concrete is lower than the temperature stress or the shrinkage stress, the high-strength concrete can crack. In order to solve the problem of cracking, the invention adopts the following technical means:
(1) The viscosity reducer is prepared by mainly using the limestone powder and the microbeads, so that the viscosity and the yield stress of high-strength concrete are remarkably reduced, the pumping performance of the concrete is improved, and most importantly, the adiabatic temperature rise is reduced. The limestone powder is used for improving the distribution state among cement slurry particles to enable the particle size distribution of the cement slurry particles to be close to fullerene distribution, and meanwhile, the limestone powder is also used for filling pores among the cement particles to play a role in reducing water, and under the condition that the water consumption is the same, the surplus water content of the system can be increased, so that the rheological property of the system is improved. The microbeads are smooth spherical particles, can play a roll ball effect in concrete, are beneficial to relative sliding among concrete particles, reduce the viscosity and yield stress of the concrete and improve the working performance and rheological property of the concrete.
(2) The invention takes microcapsules and an expanding agent as main bodies of repair materials, and adds basalt fibers to repair cracked concrete, wherein: the microcapsule wall material adopts glucose modified urea-formaldehyde resin, and the glucose is polyhydroxy aldehyde containing six-membered rings, so that the content of hydroxyl in the resin can be increased, acetal can be generated by the reaction of the microcapsule wall material and formaldehyde, and the defect of high content of free formaldehyde in unmodified urea-formaldehyde resin can be obviously improved; the microcapsule core material adopts glucose modified polyacrylate with good mechanical property, weather resistance and processability, and the defects of poor water resistance, hot sticking, cold brittleness and the like of unmodified polyacrylate can be overcome; the magnesium oxide expanding agent is adopted, so that the magnesium hydroxide, the magnesium carbonate trihydrate, the magnesium-rich calcite and other products can be generated through hydration reaction, the volume expansion is generated in the concrete hardening process to compensate the shrinkage, the volume stability of the concrete is improved, and the hydration products can be crystallized and precipitated at the concrete cracks to generate a self-repairing effect; the basalt fiber can play a role in resisting cracking and toughening in concrete, can reduce and refine cracks and improve the crack resistance of the concrete.
The microcapsule adopted by the invention is prepared by the following method:
1) Uniformly mixing an emulsifier and deionized water to form a solution A;
2) Adding waterborne polyurethane, acrylic acid, hydroxypropyl acrylate and octadecyl acrylate into the solution A, heating to 35 ℃, and uniformly stirring at the stirring speed of 600r/min to form emulsion B;
3) Adding sodium metabisulfite and ammonium persulfate into the emulsion B, heating to 80 ℃, and carrying out polymerization reaction to generate emulsion C;
4) Adding a defoaming agent into the emulsion C, and dispersing at a high speed to obtain an emulsion D;
5) Mixing urea and formaldehyde, uniformly stirring at the stirring speed of 400-600 r/min, adding KOH or NaOH solution, adjusting the pH of the solution to 7-9, heating to 70 ℃, and fully reacting to obtain a mixed solution E;
6) Adding glucose (15% of the weight of urea) into the mixed solution E, continuously stirring, and cooling to 50 ℃ to obtain a prepolymer F;
7) Mixing the emulsion D and the prepolymer F uniformly, stirring fully at the stirring speed of 400-500 r/min, adding HCl solution, adjusting the pH of the mixed solution to 3, and adding a catalyst NH 4 Heating Cl to 70 ℃, and reacting for 3h to generate a mixed solution G;
8) Adding resorcinol into the mixed solution G, and continuously stirring for 2 hours to form microcapsules;
9) And filtering the mixed solution containing the microcapsules, washing the mixed solution with ionized water, and performing suction filtration and drying to obtain the microcapsules.
In the following examples, in the examples of the present invention and comparative examples, P.II 52.5 portland cement was used as the cement, and the specific surface area was 335kg/m, unless otherwise specified 3 (ii) a The fly ash is F-class I fly ash, and the average grain diameter is 11.9 mu m; the specific surface area of the viscosity reducer is 1360kg/m 3 The average particle size is 3.8 mu m; river sand is medium sand in the area II, and the fineness modulus is 2.80; the lightweight aggregate is shale ceramic sand with the bulk density of 830kg/m 3 The grain diameter is 1 mm-5mm, and the water absorption rate of 24h is 12.5%; the crushed stone is 5-25 mm continuous graded crushed stone; the elastic modulus of the basalt fiber is 95GPa, the weight ratio of the long fiber to the short fiber is 7The length is 12mm, and the length of the short and long fibers is 6mm; the water reducing agent is a viscosity reduction type polycarboxylic acid high-performance water reducing agent, and the water reducing rate is 35%; the expanding agent is a magnesium oxide expanding agent, and the MgO content is 92.3 percent; the water is common tap water; the micro-beads are finished products of the fly ash, and the content and the activity of the glass bodies are higher than those of the fly ash.
In the following examples and comparative examples, the microcapsules are glucose-modified urea-formaldehyde resin-coated aqueous polyurethane-modified acrylate, the average particle size is 24.3 μm, and the core material content is 85wt%; the preparation method comprises the following steps:
1) Mixing 15g of an emulsifier (a composite emulsifier of sodium dodecyl benzene sulfonate and tween-80 in a weight ratio of 1) with 200g of deionized water to obtain an emulsifier solution, then adding 240g of waterborne polyurethane and 100g of an acrylate monomer mixture (acrylic acid, hydroxypropyl acrylate and octadecyl acrylate in a weight ratio of 3;
2) 100g of urea and 200g of formaldehyde solution (molar ratio, urea: formaldehyde = 1) is stirred uniformly, the pH value of the solution is adjusted to be 7-9, 15g of glucose is added, the reaction is carried out for 2 hours at 70 ℃ to obtain a glucose modified urea formaldehyde resin prepolymer, 300g of dispersed aqueous polyurethane modified acrylate core material emulsion is added into the glucose modified urea formaldehyde resin prepolymer, the pH value is adjusted to be 3, and then a catalyst NH is added 4 And Cl, stirring uniformly, reacting for 3h, finally adding 8g of resorcinol, mixing uniformly, reacting for 2h, filtering, washing and drying to obtain the microcapsule of the glucose modified urea-formaldehyde resin coated waterborne polyurethane modified acrylate.
Example 1
The low-temperature-rise anti-crack concrete provided by the embodiment comprises the following raw materials in percentage by weight:
230kg/m cement 3 135kg/m of fly ash 3 95kg/m viscosity reducer 3 Microcapsules 10kg/m 3 480kg/m river sand 3 140kg/m of ceramic sand 3 1096kg/m of crushed stone 3 Basalt fiber 3kg/m 3 6kg/m of water reducing agent 3 20kg/m of an expanding agent 3 140kg/m of water 3 . The raw material formulation is detailed in table 1.
The preparation method of the low-temperature-rise anti-crack concrete provided by the embodiment comprises the following steps:
1) Weighing the raw materials;
2) Uniformly mixing the weighed pottery sand with 10% of the total water amount, and performing pre-wetting treatment;
3) Pouring cement, fly ash, a viscosity reducer, microcapsules and an expanding agent into a stirring pot, and continuously stirring for 1min to obtain mixed powder;
4) Adding the pre-wetted pottery sand into the mixed powder, continuously stirring for 30s, adding river sand and broken stone, and continuously stirring for 30s to obtain a mixed dry mixture;
5) And (3) uniformly mixing the water reducing agent and 70% of water, adding the mixture into the dry mixture, continuously stirring for 30s, pouring all the remaining water into a stirring pot, and continuously stirring for 2-3 min to obtain the low-temperature-rise anti-crack concrete.
Example 2
The low-temperature-rise anti-crack concrete provided by the embodiment comprises the following raw materials:
cement 240kg/m 3 128kg/m of fly ash 3 90kg/m of viscosity reducer 3 Microcapsules of 12kg/m 3 480kg/m river sand 3 140kg/m of ceramic sand 3 1096kg/m of crushed stone 3 Basalt fiber 3kg/m 3 6kg/m of water reducing agent 3 20kg/m of an expanding agent 3 140kg/m of water 3 . The raw material formulation is detailed in table 1.
The preparation method of the low-temperature-rise anti-crack concrete provided by the embodiment comprises the following steps of:
1) Weighing the raw materials;
2) Uniformly mixing the weighed pottery sand with 10% of the total water amount, and carrying out pre-wetting treatment;
3) Pouring cement, fly ash, a viscosity reducer, microcapsules and an expanding agent into a stirring pot, and continuously stirring for 1min to obtain mixed powder;
4) Adding the pre-wetted pottery sand into the mixed powder, continuously stirring for 30s, adding river sand and broken stone, and continuously stirring for 30s to obtain a mixed dry mixture;
5) And (3) uniformly mixing the water reducing agent and 70% of water, adding the mixture into the dry mixture, continuously stirring for 30s, pouring all the remaining water into a stirring pot, and continuously stirring for 2-3 min to obtain the low-temperature-rise anti-crack concrete.
Example 3
The low-temperature-rise anti-crack concrete provided by the embodiment comprises the following raw materials:
cement 255kg/m 3 105kg/m of fly ash 3 95kg/m viscosity reducer 3 Microcapsules 10kg/m 3 428kg/m river sand 3 Ceramic sand 160kg/m 3 1096kg/m of crushed stone 3 Basalt fiber 3kg/m 3 6kg/m of water reducing agent 3 20kg/m of an expanding agent 3 140kg/m of water 3 . The raw material formulation is detailed in table 1.
The preparation method of the low-temperature-rise anti-crack concrete provided by the embodiment comprises the following steps:
1) Weighing the raw materials;
2) Uniformly mixing the weighed pottery sand with 10% of the total water amount, and carrying out pre-wetting treatment;
3) Pouring cement, fly ash, viscosity reducer, microcapsule and expanding agent into a stirring pot, and continuously stirring for 1min to obtain mixed powder;
4) Adding the pre-wetted pottery sand into the mixed powder, continuously stirring for 30s, adding river sand and broken stone, and continuously stirring for 30s to obtain a mixed dry mixture;
5) And (3) uniformly mixing the water reducing agent and 70% of water, adding the mixture into the dry mixture, continuously stirring for 30s, pouring all the residual water into a stirring pot, and continuously stirring for 2-3 min to obtain the low-temperature-rise anti-crack concrete.
Comparative example 1
The raw material formula and the preparation method of the low-temperature-rise anti-crack concrete provided by the comparative example are basically the same as those of the example 1, and the difference is that: the raw materials of the composite material are not added with microcapsules, ceramic sand, basalt fibers and an expanding agent, and the formula of the raw materials is detailed in table 1.
Comparative example 2
The raw material formula and the preparation method of the low-temperature-rise anti-crack concrete provided by the comparative example are basically the same as those of the example 1, and the difference is that: the viscosity reducer is not added, and the raw material formula is detailed in table 1.
Comparative example 3
The raw material formula and the preparation method of the low-temperature-rise anti-crack concrete provided by the comparative example are basically the same as those of the example 1, and the difference is that: the pottery sand is not added, the river sand is adopted completely, and the raw material formula is shown in table 1.
Comparative example 4
The raw material formula and the preparation method of the low-temperature-rise anti-crack concrete provided by the comparative example are basically the same as those of the example 1, and the difference is that: basalt fibers are not added, and the raw material formula is detailed in table 1.
Comparative example 5
The raw material formula and the preparation method of the low-temperature-rise anti-crack concrete provided by the comparative example are basically the same as those of the example 1, and the difference is that: the raw materials are shown in table 1 in detail.
Comparative example 6
The raw material formula and the preparation method of the low-temperature-rise anti-crack concrete provided by the comparative example are basically the same as those of the example 1, and the difference is that: the microcapsules were not incorporated and the raw material formulation is detailed in table 1.
TABLE 1 examples 1-3, comparative examples 1-6 increase the mix ratio (kg/m) of the crack-resistant concrete at low temperature 3 )
Table 2 working properties and rheological properties of low temperature elevated crack resistant concrete provided in examples 1 to 3 and comparative examples 1 to 6
TABLE 3 mechanical Properties, adiabatic temperature rise crack resistance, and durability of the low-temperature rise crack resistant concretes provided in examples 1 to 3 and comparative examples 1 to 6
Table 4 self-repairing Properties of low temperature rise crack resistant concretes provided in examples 1 to 3 and comparative examples 1 to 6
The results in tables 2, 3 and 4 show that the lightweight aggregate, the basalt fiber and the expanding agent can obviously influence the shrinkage performance of the concrete, the viscosity reducer can obviously reduce the adiabatic temperature rise of the concrete and improve the rheological property of the concrete, and overall, the low-temperature-rise anti-crack concrete prepared by the method has better various properties and can meet the actual construction requirements. In addition, after the microcapsule is doped, the self-repairing capability of the concrete can be obviously improved while other performances of the concrete are not influenced.
The results in tables 2, 3 and 4 show that the C60 concrete prepared by the invention has lower heat insulation temperature rise value and drying shrinkage, and the concrete has excellent crack resistance and pumping performance while maintaining high mechanical property and good durability. Secondly, the self-repairing system established by the invention has high repairing efficiency when the concrete cracks, greatly prolongs the service life of the concrete, reduces the later-stage maintenance cost of the concrete, and has good economic benefit and social benefit. The low-temperature rising anti-crack concrete prepared by the method can adjust the working performance and the rheological property according to the actual construction requirement so as to meet the requirements of different construction seasons and pumping heights, and the actual pumping height can reach 200-300 m.
The above are only preferred embodiments of the present invention, and it should be noted that those skilled in the art can make various modifications and changes without departing from the inventive concept of the present invention, which falls within the protection scope of the present invention.
Claims (10)
1. The low-temperature-rise anti-crack concrete is characterized by comprising the following components: 220kg/m cement 3 ～280kg/m 3 100kg/m of fly ash 3 ～150kg/m 3 50kg/m of viscosity reducer 3 ～100kg/m 3 Microcapsules 5kg/m 3 ～15kg/m 3 400kg/m river sand 3 ～600kg/m 3 100kg/m of lightweight aggregate 3 ～200kg/m 3 1000kg/m of crushed stone 3 ～1200kg/m 3 1kg/m basalt fiber 3 ～5kg/m 3 4kg/m of water reducing agent 3 ～8kg/m 3 15kg/m of an expanding agent 3 ～30kg/m 3 120kg/m of water 3 ～150kg/m 3 。
2. The low temperature elevated crack resistant concrete according to claim 1, wherein: the water-cement ratio of the low-temperature-rise anti-crack concrete is 0.30-0.31.
3. The low temperature elevated crack resistant concrete according to claim 1, wherein: the sand rate of the low-temperature-rise anti-crack concrete is 0.25-0.28.
4. The low temperature elevated crack resistant concrete according to claim 1, wherein: the viscosity reducer comprises the following components in percentage by weight (0.01-0.03) to (0.2-0.3): (0.1-0.2) and (0.4-0.7) silica fume, microbeads, superfine mineral powder and limestone powder.
5. The low temperature elevated crack resistant concrete according to claim 1 or 4, wherein: the viscosity reducer ratioThe surface area is more than or equal to 1200kg/m 3 The average grain diameter is 2-6 μm, the viscosity ratio is not less than 60%, and the fluidity ratio is not less than 105%.
6. The low temperature elevated crack resistant concrete according to claim 1 or 4, wherein: the weight ratio of the viscosity reducer in the low-temperature-rise anti-crack concrete is 3.5-4.5%.
7. The low temperature elevated crack resistant concrete according to claim 1, wherein: the wall material of the microcapsule is glucose modified urea-formaldehyde resin, the core material is waterborne polyurethane modified acrylate, the microcapsule is spherical particles, the particle size is normally distributed, the average particle size is 20-30 μm, and the content of the core material is 70-85 wt%.
8. The low temperature elevated crack resistant concrete according to claim 7, wherein: the microcapsule is prepared by the following method:
1) Adding the mixture of the waterborne polyurethane and the acrylate monomer into an emulsifier solution, uniformly mixing to obtain a mixed emulsion, adding sodium metabisulfite and ammonium persulfate, and reacting at the temperature of 70 ℃ or above to obtain a waterborne polyurethane modified acrylate core material emulsion;
2) Uniformly mixing urea and formaldehyde in an aqueous solution, adjusting the pH value to 7-9, adding glucose, reacting at the temperature of 60 ℃ and above to obtain a glucose modified urea-formaldehyde resin prepolymer, adding an aqueous polyurethane modified acrylate core material emulsion into the modified urea-formaldehyde resin prepolymer, adjusting the pH value to 3 +/-0.5, adding a catalyst, adding resorcinol after reaction, continuing the reaction, and purifying to obtain the microcapsule of the aqueous polyurethane modified acrylate wrapped by the glucose modified urea-formaldehyde resin.
9. The low temperature elevated crack resistant concrete according to claim 1, wherein: the lightweight aggregate is ceramic sand or pumice, is subjected to pre-wetting treatment before use, has the particle size of 1-5 mm and the bulk density of 700kg/m 3 ～900kg/m 3 The cylinder pressure strength is more than or equal to 7MPa,the water absorption rate is more than or equal to 10% after 24 hours; the basalt fiber is formed by mixing long fibers and short fibers, the weight ratio of the long fibers to the short fibers is 7 3 (ii) a The water reducing agent is a viscosity reduction type polycarboxylic acid high-performance water reducing agent, and the water reducing rate is more than or equal to 30%; the expanding agent is MgO expanding agent, the MgO content is more than or equal to 90 percent, the specific surface area is more than or equal to 20000m 2 /kg。
10. Use of the low temperature elevated crack resistant concrete according to any one of claims 1 to 9 in the field of construction.
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| CN117776635A (en) * | 2024-02-28 | 2024-03-29 | 北京城建集团有限责任公司 | Large-volume shrinkage compensation impervious concrete for garbage pool and leachate pool |
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