CN113292291A - Low-cost low-shrinkage coarse aggregate UHPC suitable for cast-in-place and preparation process thereof - Google Patents
Low-cost low-shrinkage coarse aggregate UHPC suitable for cast-in-place and preparation process 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
- C04B2201/30—Mortars, concrete or artificial stone characterised by specific physical values for heat transfer properties such as thermal insulation values, e.g. R-values
- C04B2201/32—Mortars, concrete or artificial stone characterised by specific physical values for heat transfer properties such as thermal insulation values, e.g. R-values for the thermal conductivity, e.g. K-factors
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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
A coarse aggregate UHPC suitable for in-situ casting with low cost and low shrinkage and a preparation process thereof belong to the field of building materials, and aim at providing a coarse aggregate UHPC suitable for in-situ casting with low cost and low shrinkage, which comprises the following components: the high-activity joint filling material comprises water, cement, fine aggregate, basalt coarse aggregate, a high-activity mineral admixture component, a low-activity joint filling material component, steel fiber, a water reducing component and a defoaming component, wherein the mass ratio of the water, the cement, the fine aggregate, the basalt coarse aggregate, the high-activity mineral admixture component, the low-activity joint filling material component, the steel fiber, the water reducing component and the defoaming component is 0.230-0.240: 1: 1.25: 1.80-1.95: 0.18 to 0.21: 0.17-0.19: 0.19 to 0.25: 0.0155 to 0.0160, 0.00224 to 0.00230. The coarse aggregate UHPC has the advantages of ultrahigh strength, durability, low shrinkage and the like.
Description
Technical Field
The invention belongs to the technical field of building materials, and particularly relates to a low-cost low-shrinkage coarse aggregate UHPC suitable for cast-in-place and a preparation process thereof.
Background
In recent years, due to the excellent performance of UHPC, the UHPC is widely concerned, especially the ultrahigh strength and durability are far better than those of the most widely used common concrete at present, but the UHPC also has the defects of large shrinkage, high cost and large hydration heat. The shrinkage of common concrete is about 0.01%, while the shrinkage of UHPC can reach 0.05%, and the volume stability of the concrete is related to the cracking problem of an engineering structure, and is a key factor for determining the actual engineering application effect of UHPC. At present, the use of UHPC in China is mostly concentrated on prefabrication in a prefabrication field and bridge deck pavement, and the UHPC is not beneficial to popularization due to high price and poor material volume stability.
Through research and research on related documents of UHPC design and preparation, shrinkage deformation characteristics, shrinkage regulation and control technology and shrinkage reduction mechanism, the research on the design and preparation of low-shrinkage UHPC and the shrinkage reduction mechanism thereof has the following problems:
(1) the shrinkage regulation and control technology of UHPC is still not ideal, the research of each shrinkage reduction technology on the shrinkage reduction mechanism of a UHPC system is not mature enough, and the coupling effect of different shrinkage reduction mechanisms on the whole process and staged shrinkage of UHPC needs to be deeply researched and explored;
(2) the UHPC design and preparation has higher requirements on aggregates, and common is natural river sand or quartz sand with good gradation, so that the UHPC has high natural resource consumption and high cost, and therefore, a suitable green ecological natural sand substitute is necessary to be searched;
(3) the water-to-gel ratio in a UHPC system is extremely low, the mixing amount of a cementing material is large, fine aggregates are basically selected as the aggregates, coarse aggregates do not exist, the system generates larger shrinkage deformation and higher potential cracking risk, and the research on the shrinkage effect of the coarse aggregates on the UHPC has a certain engineering application value;
(4) the existing research has limited reduction degree by adding coarse aggregate, and the mixing amount of the coarse aggregate of more scholars is 400kg/m3On the left and right, it is difficult to form the framework support effect of the general concrete coarse aggregate to offset the structural shrinkage of UHPC.
In the second national concrete lecture hall of Nanjing, professor Huang political university of Hunan summarizes the problems and deficiencies of UHPC popularization and application in China, and it is important to regulate and control the shrinkage performance of UHPC according to different environmental and structural requirements.
Disclosure of Invention
The invention aims to provide a low-cost and low-shrinkage coarse aggregate UHPC suitable for in-situ casting, which can solve the problems of high shrinkage, high cost and difficult cast-in-place construction of the conventional UHPC, and the test is developed in three steps. Step one, using a cementing material and quartz sand, using EMMA Mix Analyzer software specially developed for a tight packing theory, guiding practice theoretically, and preparing a common high-flow UHPC by taking compressive strength and flexural strength as control indexes; preferably selecting high-strength aggregate, designing grain size gradation by referring to the design principle of common concrete, filling gaps of the aggregate with the UHPC slurry prepared in the step one, and taking the compressive strength and the fluidity as control indexes; and step three, doping steel fibers on the basis of the step two, and taking the fluidity and the flexural strength as control indexes. The breaking strength of the common UHPC filling slurry without steel fibers prepared by the invention is more than 30MPa and more than three times of that of common concrete, and the ultra-strong cement stone formed after the UHPC slurry is hardened laterally restrains the coarse aggregate, so that the skeleton function of the high-strength coarse aggregate is fully exerted, and meanwhile, the skeleton function can resist shrinkage, thus the UHPC coarse aggregate which is suitable for cast-in-place and has low cost and low shrinkage can be obtained.
The invention aims to provide a coarse aggregate UHPC which is suitable for cast-in-place, has low cost and low shrinkage, has stable strength, good working performance and excellent volume stability, and has the following three difficulties:
(1) conventional UHPC was formulated. The cement and the mineral admixture are preferred, the addition amount of the mineral admixture is maximized (the hydration heat is reduced), the compression strength and the flexural strength are used as control indexes, and the flexural strength of 28d without steel fiber is more than 30MPa and is used as a main control index (3-4 times of common mortar or concrete).
(2) Basalt crushed stone is preferred. The basalt broken stone is preferably graded, the maximum grain size is less than 26.5mm, the apparent density of stones is more than 3.15, the mixture of UHPC slurry and stones is convenient to have a better blending proportion, meanwhile, the volume weight of the stones is about 30 percent larger than that of the slurry, and the slurry is pushed to flow in the process of sinking and self-compacting the stones, so that the coarse aggregate UHPC has excellent fluidity.
The particle size of the pebbles is selected to be matched with the diameter of the steel fiber. The uniformly scattered steel fibers in the mixture can block the movement of the stones, the length of the fibers is certain, the larger the particle size of the stones is, the larger the blocking effect is, the particle size of the stones is certain, and the longer the fibers are, the larger the blocking effect is. So the preferred length of steel fiber and particle size of stone is a difficult task of the present invention.
The invention adopts the following technical scheme:
a coarse aggregate UHPC suitable for cast-in-place low-cost low-shrinkage comprises the following components: the high-activity joint filling material comprises water, cement, fine aggregate, basalt coarse aggregate, a high-activity mineral admixture component, a low-activity joint filling material component, steel fiber, a water reducing component and a defoaming component, wherein the mass ratio of the water, the cement, the fine aggregate, the basalt coarse aggregate, the high-activity mineral admixture component, the low-activity joint filling material component, the steel fiber, the water reducing component and the defoaming component is 0.230-0.240: 1: 1.25: 1.80-1.95: 0.18 to 0.21: 0.17-0.19: 0.19 to 0.25: 0.0155 to 0.0160, 0.00224 to 0.00230.
Further, the cement is P.O 52.5.5 ordinary portland cement.
Further, the fine aggregate is quartz sand with the apparent density of 2500kg/m3～2700kg/m3The particle size range is as follows: 0.15 mm-0.6 mm, 40-80 meshes.
Further, the basalt coarse aggregate is basalt broken stone, and the apparent density of the raw stone is 3.2g/cm3Compressive strength of single axis>200MPa, the flake content of the broken stone is about 7.6, the water absorption is 0.3, the firmness index is 1.1, the polishing value is 52, the stone powder content is 0.4, the abrasion value of los angeles is 17.6, and the particle size comprises four intervals of 3-5 mm, 5-10 mm, 10-15 mm and 15-25 mm, and the broken stone can be compounded according to the proportioning requirement.
Further, the high-activity mineral admixture comprises superfine mineral powder and ground fly ash in a mass ratio of 1:1, wherein the particle size distribution of the superfine mineral powder is 1-10 mu m, and the specific surface area is 800-1000 m2Kg, apparent density 2.72g/cm3Index of activity135 of the total weight of the raw materials; the particle size distribution of the fine grinding coal ash is 1-10 mu m, and the specific surface area is 800-2Kg, apparent density 2.65g/cm3And an activity index of 130.
Further, the low-activity joint filler comprises the following components of superfine heavy calcium powder and quartz powder: the mass ratio of the quartz powder is 2.8: 1, wherein the specific surface area of the superfine heavy calcium powder is 370-380 m2Kg, 325 mesh, apparent density 2.6g/cm3(ii) a The specific surface area of the quartz powder is 350-380 m2Kg, 330-350 meshes, and apparent density of 2.68g/cm3。
Furthermore, the diameter of the steel fiber is 0.2-0.3 mm, the length of the steel fiber is 12-15 mm, and the tensile strength of the steel fiber is 1500-2000 MPa.
Further, the water reducing component comprises a high-performance polycarboxylic acid water reducing agent for common concrete, and the defoaming component comprises an ether emulsion defoaming agent for common concrete.
A preparation method of a coarse aggregate UHPC suitable for cast-in-place low-cost low-shrinkage comprises the following steps:
firstly, preparing water, cement, fine aggregate, basalt coarse aggregate, a high-activity mineral admixture component, a low-activity joint filling material component, steel fiber, a water reducing component and a defoaming component according to the above proportion;
secondly, pre-wetting a cylinder of a stirrer, then putting cement, fine aggregate, basalt coarse aggregate, a high-activity mineral admixture component and a low-activity joint filler component into the stirrer, pre-stirring for 1-2 min, then adding a water reducing component, a defoaming component and water, and stirring for 3-5 min;
and step three, uniformly dispersing the steel fibers into the mixture obtained in the step two, and stirring for 1-2 min to obtain the coarse aggregate UHPC mixture.
The invention is invented based on the defects of high shrinkage, high cost and difficult cast-in-place construction of the conventional UHPC, the development principle comprises the compact packing theory of the UHPC and the framework action principle of the common concrete, namely: the UHPC high-flow slurry is used for filling gaps of the coarse aggregate, and the cement stone after the UHPC slurry is hardened is used for forming the ultra-high tensile strength lateral constraint coarse aggregate, so that the strength of the coarse aggregate is fully exerted, the selected coarse aggregate is the basalt macadam, and the uniaxial compressive strength can reach more than 200MPa, so that the UHPC coarse aggregate designed by using the UHPC design principle and the common concrete design principle has the advantages of ultra-high strength, durability, low shrinkage and the like.
Mineral admixtures of the invention: cement: aggregate ≈ 0.16: 0.23: 1, about 1.1: 1, the hydration heat per unit volume of the invention is small, the adiabatic temperature rise is less than 70 ℃, the invention is suitable for the cast-in-place of large-volume and special-shaped components, the invention is successfully applied to the foundation reinforcement engineering of large-scale wind driven generators, the cracking is not generated, the aggregate price is relatively low, and the material cost can be reduced by about 40-60% (compared with the common UHPC).
The invention has the following beneficial effects:
1. the cast-in-place low-cost low-shrinkage coarse aggregate UHPC is prepared from water, cement, fine aggregate, basalt coarse aggregate, a high-activity mineral admixture component, a low-activity joint filler component, steel fiber, a water reducing component and a defoaming component. The invention adopts water, cement, fine aggregate, high-activity mineral admixture component, low-activity joint filling material component, water reducing component and defoaming component to prepare the compact-packed common UHPC, preferably selects high-strength basalt broken stone as the coarse aggregate, and has one proportion giving consideration to the closest packing theory of the UHPC and the skeleton action principle of the common concrete. Therefore, the coarse aggregate UHPC not only has the high strength of the conventional UHPC, but also has the volume stability characteristic of the common concrete, and is more superior to the common UHPC in comprehensive performance.
2. The invention pours the coarse aggregate UHPC with low cost and low shrinkage on site, wherein the coarse aggregate accounts for 40-50% of the total mass of the mixture and 35-45% of the total volume, thus greatly reducing the dosage of the cementing material in unit volume. The unit price of the cementing material is about 8-10 times of that of basalt macadam, and the cost is saved remarkably. The performance of the coarse aggregate UHPC can basically replace the use of cast-in-place ordinary UHPC, the requirements on quartz sand and cementing materials are greatly relieved, and the invention has the advantages of simple formula, low cost and wide application value.
3. The invention is suitable for casting the UHPC coarse aggregate with low cost and low shrinkage on site, uses common materials, has a stirring form similar to that of common concrete, has short time, is simple to cast and maintain, is closer to the production general knowledge of construction workers, can effectively avoid the cracking of the UHPC performance caused by the construction process which is suitable for common concrete and is different from the UHPC, and is beneficial to market popularization.
4. The invention is suitable for casting the coarse aggregate UHPC with low cost and low shrinkage in situ, has stable strength, good working performance, excellent volume stability, slump expansion degree of 650-750 mm, can realize self-leveling and has better use value.
5. The invention is suitable for casting the low-cost and low-shrinkage coarse aggregate UHPC on site, the stirring time is less than 10min, the binding material proportion is smaller, the stirring resistance is smaller, the forced stirrer with common power on the construction site can stir, and the invention has better popularization significance.
6. The invention is suitable for casting the coarse aggregate UHPC with low cost and low shrinkage in site, the 28d standard compressive strength is more than 130MPa, the steam curing strength can reach 170-180MPa, and the compressive strength has smaller discreteness and more stable strength due to the doping of more coarse aggregates.
7. The coarse aggregate UHPC suitable for in-situ casting with low cost and low shrinkage has smaller shrinkage which is about 100 mu epsilon because more coarse aggregates are doped, is far smaller than the conventional UHPC, has stronger anti-cracking performance, and is more suitable for large-volume and large-volume structures in-situ casting.
8. The coarse aggregate UHPC suitable for cast-in-place low-cost and low-shrinkage is suitable for cast-in-place large-volume concrete because more coarse aggregates are doped, the proportion of mineral admixture is larger, the cement consumption is relatively less, and the method is suitable for cast-in-place large-volume concrete.
9. The low-cost and low-shrinkage coarse aggregate UHPC suitable for in-situ casting is lower in cost and is 40-60% cheaper than a common UHPC material due to the fact that more coarse aggregates are doped, and the mixing amount of the pour point depressant and quartz sand is greatly reduced, and market popularization is facilitated.
Detailed Description
Example 1
A coarse aggregate UHPC suitable for cast-in-place low-cost low-shrinkage is mainly prepared from the following raw materials: the high-activity joint filling material is prepared from water, cement, fine aggregate, basalt coarse aggregate, a high-activity mineral admixture component, a low-activity joint filling material component, steel fiber, a water reducing component and a defoaming component, wherein the mass ratio of the water, the cement, the fine aggregate, the basalt coarse aggregate, the high-activity mineral admixture component, the low-activity joint filling material component, the steel fiber, the water reducing component and the defoaming component is 0.230: 1: 1.25: 1.95: 0.21: 0.17: 0.25: 0.0158 and 0.00225.
The cement is P.O 52.5.5 ordinary portland cement.
The fine aggregate is quartz sand, and the apparent density of the fine aggregate is 2500kg/m3～2700kg/m3The particle size range of the fine aggregate is as follows: 0.15 mm-0.6 mm, 40-80 meshes.
The basalt coarse aggregate is basalt broken stone produced in filial piety city of Hubei province, and the apparent density of the raw stone is 3.2g/cm3Compressive strength of single axis>200MPa, the flake content of the broken stone is about 7.6, the water absorption is 0.3, the firmness index is 1.1, the polishing value is 52, the stone powder content is 0.4, the los Angeles abrasion value is 17.6, and the particle size comprises four intervals of 3-5 mm 0%, 5-10 mm 30%, 10-15 mm 0% and 15-25 mm 70%.
The high-activity mineral admixture comprises superfine mineral powder and pulverized coal ash. The particle size distribution of the superfine mineral powder is 1-10 mu m, and the specific surface area is 800-1000 m2Kg, apparent density 2.72g/cm3An activity index of 135; the particle size distribution of the fine grinding coal ash is 1-10 mu m, and the specific surface area is 800-2Kg, apparent density 2.65g/cm3And an activity index of 130. Superfine mineral powder: grinding fine coal ash is 1: 1.
the low-activity joint filler comprises the following components of superfine heavy calcium powder, quartz powder and superfine heavy calcium powder: the mass ratio of the quartz powder is 2.8: 1. the specific surface area of the coarse whiting powder is 370-380 m2Kg, 325 mesh, apparent density 2.6g/cm3(ii) a The specific surface area of the quartz powder is 350-380 m2Kg, 330-350 meshes, and apparent density of 2.68g/cm3。
The diameter of the steel fiber is 0.2-0.3 mm, the length of the steel fiber is 12-15 mm, and the tensile strength of the steel fiber is 1500-2000 MPa.
The water reducing component and the defoaming component are high-performance polycarboxylic acid water reducing agent and ether emulsion defoaming agent for common concrete.
The preparation method of the cast-in-place low-cost low-shrinkage coarse aggregate UHPC comprises the following steps:
(1) preparing water, cement, fine aggregate, basalt coarse aggregate, a high-activity mineral admixture component, a low-activity joint filling material component, steel fiber, a water reducing component and a defoaming component according to the mass ratio;
(2) pre-wetting a barrel of a stirrer, then putting cement, fine aggregate, basalt coarse aggregate, a high-activity mineral admixture component and a low-activity joint filling material component into the stirrer, pre-stirring for 1-2 min, then adding a water reducing component, a defoaming component and water, and stirring for 3-5 min;
(3) and (3) uniformly dispersing the steel fibers into the mixture obtained in the step (2), and stirring for 1-2 min to obtain the coarse aggregate UHPC mixture.
Example 2
A coarse aggregate UHPC suitable for cast-in-place low-cost low-shrinkage is mainly prepared from the following raw materials: the high-activity joint filling material is prepared from water, cement, fine aggregate, basalt coarse aggregate, a high-activity mineral admixture component, a low-activity joint filling material component, steel fiber, a water reducing component and a defoaming component, wherein the mass ratio of the water, the cement, the fine aggregate, the basalt coarse aggregate, the high-activity mineral admixture component, the low-activity joint filling material component, the steel fiber, the water reducing component and the defoaming component is 0.235: 1: 1.25: 1.90: 0.21: 0.18: 0.22: 0.01560, 0.00228.
The cement is P.O 52.5.5 ordinary portland cement.
The fine aggregate is quartz sand, and the apparent density of the fine aggregate is 2500kg/m3～2700kg/m3The particle size range of the fine aggregate is as follows: 0.15 mm-0.6 mm, 40-80 meshes.
The basalt coarse aggregate is basalt broken stone produced in filial piety city of Hubei province, and the apparent density of the raw stone is 3.2g/cm3Compressive strength of single axis>200MPa, a macadam pin flake content of about 7.6, a water absorption of 0.3, a firmness index of 1.1, a polished value of 52, a stone dust content of 0.4, los AngelesThe abrasion value is 17.6, and the particle size comprises four ranges of 3-5 mm to 10%, 5-10 mm to 25%, 10-15 mm to 0% and 15-25 mm to 65%.
The high-activity mineral admixture comprises superfine mineral powder and pulverized coal ash. The particle size distribution of the superfine mineral powder is 1-10 mu m, and the specific surface area is 800-1000 m2Kg, apparent density 2.72g/cm3An activity index of 135; the particle size distribution of the fine grinding coal ash is 1-10 mu m, and the specific surface area is 800-2Kg, apparent density 2.65g/cm3And an activity index of 130. Superfine mineral powder: grinding fine coal ash is 1: 1.
the low-activity joint filler comprises the following components of superfine heavy calcium powder, quartz powder and superfine heavy calcium powder: the mass ratio of the quartz powder is 2.8: 1. the specific surface area of the coarse whiting powder is 370-380 m2Kg, 325 mesh, apparent density 2.6g/cm3(ii) a The specific surface area of the quartz powder is 350-380 m2Kg, 330-350 meshes, and apparent density of 2.68g/cm3。
The diameter of the steel fiber is 0.2-0.3 mm, the length of the steel fiber is 12-15 mm, and the tensile strength of the steel fiber is 1500-2000 MPa.
The water reducing component and the defoaming component are high-performance polycarboxylic acid water reducing agent and ether emulsion defoaming agent for common concrete.
The preparation method of this example is the same as example 1.
Example 3
A coarse aggregate UHPC suitable for cast-in-place low-cost low-shrinkage is mainly prepared from the following raw materials: the high-activity joint filling material is prepared from water, cement, fine aggregate, basalt coarse aggregate, a high-activity mineral admixture component, a low-activity joint filling material component, steel fiber, a water reducing component and a defoaming component, wherein the mass ratio of the water, the cement, the fine aggregate, the basalt coarse aggregate, the high-activity mineral admixture component, the low-activity joint filling material component, the steel fiber, the water reducing component and the defoaming component is 0.235: 1: 1.25: 1.95: 0.20: 0.17: 0.25: 0.0160 and 0.00224.
The cement is P.O 52.5.5 ordinary portland cement.
The fine aggregate is quartz sand, and the apparent density of the fine aggregate is 2500kg/m3～2700kg/m3Granules of fine aggregateThe diameter range is as follows: 0.15 mm-0.6 mm, 40-80 meshes.
The basalt coarse aggregate is basalt broken stone produced in filial piety city of Hubei province, and the apparent density of the raw stone is 3.2g/cm3Compressive strength of single axis>200MPa, the flake content of the broken stone is about 7.6, the water absorption is 0.3, the firmness index is 1.1, the polishing value is 52, the stone powder content is 0.4, the los Angeles abrasion value is 17.6, and the particle size comprises four intervals of 3-5 mm 0%, 5-10 mm 0%, 10-15 mm 100% and 15-25 mm 0%.
The high-activity mineral admixture comprises superfine mineral powder and pulverized coal ash. The particle size distribution of the superfine mineral powder is 1-10 mu m, and the specific surface area is 800-1000 m2Kg, apparent density 2.72g/cm3An activity index of 135; the particle size distribution of the fine grinding coal ash is 1-10 mu m, and the specific surface area is 800-2Kg, apparent density 2.65g/cm3And an activity index of 130. Superfine mineral powder: grinding fine coal ash is 1: 1.
the low-activity joint filler comprises the following components of superfine heavy calcium powder, quartz powder and superfine heavy calcium powder: the mass ratio of the quartz powder is 2.8: 1. the specific surface area of the coarse whiting powder is 370-380 m2Kg, 325 mesh, apparent density 2.6g/cm3(ii) a The specific surface area of the quartz powder is 350-380 m2Kg, 330-350 meshes, and apparent density of 2.68g/cm3。
The diameter of the steel fiber is 0.2-0.3 mm, the length of the steel fiber is 12-15 mm, and the tensile strength of the steel fiber is 1500-2000 MPa.
The water reducing component and the defoaming component are high-performance polycarboxylic acid water reducing agent and ether emulsion defoaming agent for common concrete.
The preparation method of this example is the same as example 1.
Example 4
A coarse aggregate UHPC suitable for cast-in-place low-cost low-shrinkage is mainly prepared from the following raw materials: the high-activity joint filling material is prepared from water, cement, fine aggregate, basalt coarse aggregate, a high-activity mineral admixture component, a low-activity joint filling material component, steel fiber, a water reducing component and a defoaming component, wherein the mass ratio of the water, the cement, the fine aggregate, the basalt coarse aggregate, the high-activity mineral admixture component, the low-activity joint filling material component, the steel fiber, the water reducing component and the defoaming component is 0.240: 1: 1.25: 1.95: 0.18: 0.17: 0.19: 0.0155 and 0.00224.
The cement is P.O 52.5.5 ordinary portland cement.
The fine aggregate is quartz sand, and the apparent density of the fine aggregate is 2500kg/m3～2700kg/m3The particle size range of the fine aggregate is as follows: 0.15 mm-0.6 mm, 40-80 meshes.
The basalt coarse aggregate is basalt broken stone produced in filial piety city of Hubei province, and the apparent density of the raw stone is 3.2g/cm3Compressive strength of single axis>200MPa, the flake content of the broken stone is about 7.6, the water absorption is 0.3, the firmness index is 1.1, the polishing value is 52, the stone powder content is 0.4, the los Angeles abrasion value is 17.6, and the particle size comprises four intervals of 3-5 mm 0%, 5-10 mm 100%, 10-15 mm 0% and 15-25 mm 0%.
The high-activity mineral admixture comprises superfine mineral powder and pulverized coal ash. The particle size distribution of the superfine mineral powder is 1-10 mu m, and the specific surface area is 800-1000 m2Kg, apparent density 2.72g/cm3An activity index of 135; the particle size distribution of the fine grinding coal ash is 1-10 mu m, and the specific surface area is 800-2Kg, apparent density 2.65g/cm3And an activity index of 130. Superfine mineral powder: grinding fine coal ash is 1: 1.
the low-activity joint filler comprises the following components of superfine heavy calcium powder, quartz powder and superfine heavy calcium powder: the mass ratio of the quartz powder is 2.8: 1. the specific surface area of the coarse whiting powder is 370-380 m2Kg, 325 mesh, apparent density 2.6g/cm3(ii) a The specific surface area of the quartz powder is 350-380 m2Kg, 330-350 meshes, and apparent density of 2.68g/cm3。
The diameter of the steel fiber is 0.2-0.3 mm, the length of the steel fiber is 12-15 mm, and the tensile strength of the steel fiber is 1500-2000 MPa.
The water reducing component and the defoaming component are high-performance polycarboxylic acid water reducing agent and ether emulsion defoaming agent for common concrete.
The preparation method of this example is the same as example 1.
Example 5
A coarse aggregate UHPC suitable for cast-in-place low-cost low-shrinkage is mainly prepared from the following raw materials: the high-activity joint filling material is prepared from water, cement, fine aggregate, basalt coarse aggregate, a high-activity mineral admixture component, a low-activity joint filling material component, steel fiber, a water reducing component and a defoaming component, wherein the mass ratio of the water, the cement, the fine aggregate, the basalt coarse aggregate, the high-activity mineral admixture component, the low-activity joint filling material component, the steel fiber, the water reducing component and the defoaming component is 0.230: 1: 1.25: 1.95: 0.21: 0.17-0.19: 0.19: 0.0155 and 0.000230.
The cement is P.O 52.5.5 ordinary portland cement.
The fine aggregate is quartz sand, and the apparent density of the fine aggregate is 2500kg/m3～2700kg/m3The particle size range of the fine aggregate is as follows: 0.15 mm-0.6 mm, 40-80 meshes.
The basalt coarse aggregate is basalt broken stone produced in filial piety city of Hubei province, and the apparent density of the raw stone is 3.2g/cm3Compressive strength of single axis>200MPa, the flake content of the broken stone is about 7.6, the water absorption is 0.3, the firmness index is 1.1, the polishing value is 52, the stone powder content is 0.4, the los Angeles abrasion value is 17.6, and the particle size comprises four intervals of 3-5 mm to 18%, 5-10 mm to 0%, 10-15 mm to 12% and 15-25 mm to 70%.
The high-activity mineral admixture comprises superfine mineral powder and pulverized coal ash. The particle size distribution of the superfine mineral powder is 1-10 mu m, and the specific surface area is 800-1000 m2Kg, apparent density 2.72g/cm3An activity index of 135; the particle size distribution of the fine grinding coal ash is 1-10 mu m, and the specific surface area is 800-2Kg, apparent density 2.65g/cm3And an activity index of 130. Superfine mineral powder: grinding fine coal ash is 1: 1.
the low-activity joint filler comprises the following components of superfine heavy calcium powder, quartz powder and superfine heavy calcium powder: the mass ratio of the quartz powder is 2.8: 1. the specific surface area of the coarse whiting powder is 370-380 m2Kg, 325 mesh, apparent density 2.6g/cm3(ii) a The specific surface area of the quartz powder is 350-380 m2Kg, 330-350 meshes, and apparent density of 2.68g/cm3。
The diameter of the steel fiber is 0.2-0.3 mm, the length of the steel fiber is 12-15 mm, and the tensile strength of the steel fiber is 1500-2000 MPa.
The water reducing component and the defoaming component are high-performance polycarboxylic acid water reducing agent and ether emulsion defoaming agent for common concrete.
The preparation method of this example is the same as example 1.
Strength test
The testing steps are as follows: respectively loading the polypropylene fiber concrete obtained in the embodiments 1-5 of the invention into test molds at one time, inserting and tamping the polypropylene fiber concrete along the walls of each test mold by using a spatula during loading, then placing the test molds on a vibration table, vibrating the test molds for two times, scraping off redundant cast-in-place coarse aggregate UHPC with low cost and low shrinkage at the openings of the test molds, then trowelling the coarse aggregate UHPC, placing the coarse aggregate UHPC into a concrete curing box for curing for 24 hours, removing the molds, finally moving the coarse aggregate into a standard concrete curing room for curing, and taking out the coarse aggregate after 28 days.
According to the specified method of GB/T50081-2002 standard of mechanical property test method of common concrete, the strength of the UHPC test block of the cast-in-place coarse aggregate with low cost and low shrinkage is detected, and the test result is shown in Table 1.
TABLE 1 Strength test results of Polypropylene fiber recycled concrete obtained in examples 1 to 5 of the present invention
Claims (9)
1. A coarse aggregate UHPC suitable for cast-in-place low-cost low-shrinkage is characterized in that: comprises the following components: the high-activity joint filling material comprises water, cement, fine aggregate, basalt coarse aggregate, a high-activity mineral admixture component, a low-activity joint filling material component, steel fiber, a water reducing component and a defoaming component, wherein the mass ratio of the water, the cement, the fine aggregate, the basalt coarse aggregate, the high-activity mineral admixture component, the low-activity joint filling material component, the steel fiber, the water reducing component and the defoaming component is 0.230-0.240: 1: 1.25: 1.80-1.95: 0.18 to 0.21: 0.17-0.19: 0.19 to 0.25: 0.0155 to 0.0160, 0.00224 to 0.00230.
2. The coarse aggregate UHPC suitable for cast-in-place low-cost and low-shrinkage according to claim 1, which is characterized in that: the cement is P.O 52.5.5 ordinary portland cement.
3. The coarse aggregate UHPC suitable for cast-in-place low-cost and low-shrinkage according to claim 2, which is characterized in that: the fine aggregate is quartz sand with apparent density of 2500kg/m3～2700kg/m3The particle size range is as follows: 0.15 mm-0.6 mm, 40-80 meshes.
4. The coarse aggregate UHPC suitable for cast-in-place low-cost and low-shrinkage according to claim 3, which is characterized in that: the basalt coarse aggregate is basalt broken stone, and the apparent density of the raw stone is 3.2g/cm3Compressive strength of single axis>200MPa, the flake content of the broken stone is about 7.6, the water absorption is 0.3, the firmness index is 1.1, the polishing value is 52, the stone powder content is 0.4, the abrasion value of los angeles is 17.6, and the particle size comprises four intervals of 3-5 mm, 5-10 mm, 10-15 mm and 15-25 mm.
5. The coarse aggregate UHPC suitable for cast-in-place low-cost and low-shrinkage according to claim 4, wherein: the high-activity mineral admixture comprises superfine mineral powder and ground fly ash in a mass ratio of 1:1, wherein the particle size distribution of the superfine mineral powder is 1-10 mu m, and the specific surface area is 800-1000 m2Kg, apparent density 2.72g/cm3An activity index of 135; the particle size distribution of the fine grinding coal ash is 1-10 mu m, and the specific surface area is 800-2Kg, apparent density 2.65g/cm3And an activity index of 130.
6. The UHPC coarse aggregate suitable for cast-in-place low-cost and low-shrinkage according to claim 5, wherein: the low-activity joint filler comprises the following components of superfine heavy calcium powder, quartz powder and superfine heavy calcium powder: the mass ratio of the quartz powder is 2.8: 1, wherein the specific surface area of the superfine heavy calcium powder is 370-380 m2Kg, 325 mesh, apparent density 2.6g/cm3(ii) a The specific surface area of the quartz powder is 350-380 m2Kg, 330-350 meshes, and apparent density of 2.68g/cm3。
7. The UHPC coarse aggregate suitable for cast-in-place low-cost and low-shrinkage as claimed in claim 6, wherein: the diameter of the steel fiber is 0.2-0.3 mm, the length of the steel fiber is 12-15 mm, and the tensile strength of the steel fiber is 1500-2000 MPa.
8. The UHPC coarse aggregate suitable for cast-in-place low-cost low-shrinkage according to claim 7, wherein: the water reducing component comprises a high-performance polycarboxylic acid water reducing agent for common concrete, and the defoaming component comprises an ether emulsion defoaming agent for common concrete.
9. A method for preparing a coarse aggregate UHPC suitable for cast-in-place low cost and low shrinkage according to any of claims 1 to 8, wherein the method comprises the following steps: the method comprises the following steps:
firstly, preparing water, cement, fine aggregate, basalt coarse aggregate, a high-activity mineral admixture component, a low-activity joint filling material component, steel fiber, a water reducing component and a defoaming component according to the above proportion;
secondly, pre-wetting a cylinder of a stirrer, then putting cement, fine aggregate, basalt coarse aggregate, a high-activity mineral admixture component and a low-activity joint filler component into the stirrer, pre-stirring for 1-2 min, then adding a water reducing component, a defoaming component and water, and stirring for 3-5 min;
and step three, uniformly dispersing the steel fibers into the mixture obtained in the step two, and stirring for 1-2 min to obtain the coarse aggregate UHPC mixture.
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| CN115849794A (en) * | 2022-12-01 | 2023-03-28 | 中建八局第四建设有限公司 | Low-cost coarse aggregate UHPC and production facility thereof |
| CN116514488A (en) * | 2023-05-05 | 2023-08-01 | 山东高速股份有限公司 | Early strength high toughness ultra-high performance concrete and preparation method and application thereof |
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