CN112551988B - Ultrahigh-ductility concrete for earthquake-resistant engineering and preparation method thereof - Google Patents
Ultrahigh-ductility concrete for earthquake-resistant engineering and preparation method thereof Download PDFInfo
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- CN112551988B CN112551988B CN202011550469.4A CN202011550469A CN112551988B CN 112551988 B CN112551988 B CN 112551988B CN 202011550469 A CN202011550469 A CN 202011550469A CN 112551988 B CN112551988 B CN 112551988B
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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
- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/38—Fibrous materials; Whiskers
- C04B14/383—Whiskers
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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
- C04B2111/20—Resistance against chemical, physical or biological attack
- C04B2111/2038—Resistance against physical degradation
- C04B2111/2053—Earthquake- or hurricane-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
Abstract
The invention discloses ultra-high ductility concrete for earthquake-resistant engineering and a preparation method thereof, belonging to the technical field of building materials. Based on the theory of microcrack evolution effect, from the viewpoints of improving the elastic modulus of the reinforced material and increasing the development scale of microcracks in concrete, the calcium carbonate whiskers with high strength and high elastic modulus are introduced as an additional reinforced material and are assisted by an inorganic gelling agent to improve the gain effect of the calcium carbonate whiskers on the number of microcracks in the concrete, so that the ultra-high-ductility concrete material with the ultimate tensile strain not decreasing or reversely increasing along with the increase of the strain rate is prepared, and the technical problem that the ultimate tensile strain of PE-UHDC is decreased along with the increase of the strain rate is fundamentally solved.
Description
Technical Field
The invention relates to ultra-high ductility concrete for earthquake-resistant engineering and a preparation method thereof, belonging to the technical field of building materials.
Background
The ultra-high ductility concrete has ultra-high tensile strain, deformability and multi-joint cracking capability, and is increasingly widely applied to the field of building structure earthquake-resistant engineering. Currently, Polyethylene (PE) fibers are the most commonly used fiber reinforcement material for formulating ultra-high ductility concrete. The ultimate tensile strain of the polyethylene fiber reinforced ultra-high ductility concrete (PE-UHDC) is obviously higher than that of the traditional polyvinyl alcohol (PVA) fiber reinforced high ductility concrete (PVA-HDC). But like PVA-HDC, the uniaxial tensile behaviour of PE-UHDC also has a significant strain rate effect, i.e. the ultimate tensile strain of a material decreases with increasing strain rate (the time rate of change in strain, i.e. the derivative of strain with respect to time). This rate sensitivity obviously reduces the seismic capacity of PE-UHDC materials and structures. As is commonStrain rate epsilon corresponding to seismic load of&Is 1 × 10-2s-1About (belonging to the dynamic load range), and the strain rate corresponding to the loading rate of the uniaxial tensile test suggested in JC/T2461-2018 'mechanical property test method of high-ductility fiber reinforced cement-based composite material' is 1 x 10-5s-1On the left and right (belonging to the quasi-static load range), as the strain rate is increased from quasi-static to the dynamic range corresponding to the earthquake action, the ultimate tensile strain and the deformation capacity of the PE-UHDC are obviously weakened.
The reason why the ultimate tensile strain of PE-UHDC is reduced along with the increase of the strain rate can be explained by the theory of microcrack evolution effect under the action of dynamic load of concrete materials. The theory holds that: the loading rate can affect the expansion path of a single crack in the concrete, and along with the increase of the loading rate, the crack expansion path is more and more straight, so that more cracks penetrate through the aggregate; in addition, the loading rate affects the scale of development of the microcrack system in the concrete, and as the loading rate increases, the number of microcracks in the concrete at the same stress level decreases. The above two points are the main reasons why the ultimate tensile strain of PE-UHDC decreases with the increase of strain rate.
How to overcome the rate sensitivity problem of the PE-UHDC material under the action of dynamic tensile load is the key for fully exerting the PE-UHDC material and the structural performance. However, in the face of this technical problem, no relevant literature data provides a relatively ideal solution.
Disclosure of Invention
In order to solve the problem that the ultimate tensile strain of the existing PE-UHDC material is reduced along with the increase of the strain rate, the invention is based on the theory of microcrack evolution effect, and from the angles of improving the elastic modulus of a reinforced material and increasing the development scale of microcracks in concrete, by introducing calcium carbonate whiskers with high strength and high elastic modulus as an additional reinforced material and assisting an inorganic gelling agent, the gain effect of the calcium carbonate whiskers on the number of the microcracks in the concrete is improved, so that the ultra-high-ductility concrete material with the ultimate tensile strain not reduced or reversely increased along with the increase of the strain rate is prepared, and the technical problem that the ultimate tensile strain of the PE-UHDC material is reduced along with the increase of the strain rate is fundamentally solved.
In order to achieve the above object, the present invention provides an ultra-high ductility concrete for earthquake resistant engineering, the ultra-high ductility concrete comprises cement, silica fume, mineral powder, quartz sand, Polyethylene (PE) fiber, calcium carbonate whisker, a water reducing agent, hydroxyethyl cellulose, an inorganic gelling agent, an antifoaming agent, and water, wherein the amount of each component is:
in one embodiment of the invention, the cement comprises any one of portland cement, ordinary portland cement, portland slag cement, pozzolanic portland cement, portland fly ash cement, or composite portland cement.
In one embodiment of the present invention, the cement is preferably a cement having good compatibility with a water reducing agent, and most preferably a P · O52.5 type portland cement.
In one embodiment of the invention, the mass percent of silicon dioxide in the silica fume is not less than 96%, the average particle size is 0.05-0.2 μm, and the specific surface area is not less than 17000m2/kg。
In one embodiment of the invention, the mineral powder has an activity index of not less than 105% in 28 days and a specific surface area of not less than 500m2/kg。
In one embodiment of the present invention, the quartz sand has an average particle size of 0.08 to 0.13 mm.
In one embodiment of the invention, the PE fiber has a diameter of 20-40 μm, a length of 6-15 mm and a tensile strength of not less than 3000 MPa.
In one embodiment of the invention, the calcium carbonate whiskers have a diameter of 0.5-2 μm, a length of 20-30 μm, and an elastic modulus of 410-710 GPa.
In one embodiment of the present invention, the calcium carbonate whiskers are preferably aragonite-type calcium carbonate whiskers.
In one embodiment of the present invention, the water reducing agent comprises a naphthalene water reducing agent and a polycarboxylic acid water reducing agent, preferably a polycarboxylic acid high efficiency water reducing agent.
In one embodiment of the invention, the inorganic gelling agent is a gelling agent synthesized in patent publication No. CN 110304858B, a pervious concrete gelling agent.
The second object of the present invention is to provide a method for preparing the above ultra-high ductility concrete, the method comprising the steps of:
(1) weighing raw materials in proportion;
(2) mixing and dispersing 10-20% of water, calcium carbonate whiskers and hydroxyethyl cellulose to obtain a calcium carbonate whisker dispersion suspension;
(3) mixing a polycarboxylic acid high-efficiency water reducing agent and an inorganic gelling agent with 5-10% of water;
(4) mixing and stirring cement, silica fume, mineral powder and quartz sand;
(5) adding the rest water into the material obtained in the step (4), and mixing and stirring;
(6) adding the materials obtained in the step (2) and the step (3) into the material obtained in the step (5), and mixing and stirring;
(7) adding PE fibers into the material obtained in the step (6), and mixing and stirring;
(8) adding a defoaming agent into the material obtained in the step (7), and mixing and stirring to obtain the ultra-high ductility concrete;
wherein, the sequence of the step (2), the step (3) and the steps (4) to (5) can be changed or carried out simultaneously.
In one embodiment of the present invention, the mixing apparatus used in the present invention is preferably a concrete horizontal mixer.
In one embodiment of the invention, the dispersing method in the step (2) is preferably ultrasonic dispersing, the ultrasonic frequency is 19-26 kHz, and the ultrasonic time is 10-15 min.
In one embodiment of the invention, the ultrasonic dispersion is performed using an integrated ultrasonic processor.
In one embodiment of the invention, in the step (3), the water reducing agent, the inorganic gelling agent and 5-10% of water are stirred for 3-5 min in the stirring and mixing process, and the stirring speed is 50-70 r/min.
In one embodiment of the invention, the mixing and stirring in the step (4) are carried out for 3-5 min at a stirring speed of 50-70 r/min.
In one embodiment of the present invention, the mixing and stirring in step (5) is performed for 1-2 min at a stirring speed of 50-70 rpm.
In one embodiment of the invention, the mixing and stirring in the step (6) is carried out for 3-5 min at a stirring speed of 50-70 rpm.
In one embodiment of the invention, the mixing and stirring in the step (7) are carried out for 10-15 min at a stirring speed of 50-70 rpm.
In one embodiment of the present invention, the mixing and stirring in step (8) is performed for 1-2 min at a stirring speed of 50-70 rpm.
The invention also provides the application of the concrete material and the preparation method in the field of buildings.
Compared with the prior art, the invention has the following beneficial effects:
the most remarkable advantage of the ultra-high ductility concrete provided by the invention is that the concrete is quasi-static (epsilon) along with the strain rate&＝1×10-5s-1Left and right) to a dynamic range (epsilon) corresponding to seismic action&＝1×10-2s-1Left and right) with no decrease or reverse increase in ultimate tensile strain and deformability, for example, in the examples, the ultimate tensile strain of the formulated PE-UHDC is from ε&＝1×10-5s-1The increase of 3.5% to ε&＝1×10-2s-1The yield is improved by 77.1% compared with the prior art by 6.2%. The invention solves the technical problem that the ultimate tensile strain of the PE-UHDC is reduced along with the increase of the strain rate, and can further give full play to the excellent anti-seismic performance of the PE-UHDC material and the structure.
Drawings
FIG. 1 is a schematic drawing of the dimensions of a tensile test piece.
FIG. 2 is a drawing of a tensile testing apparatus.
FIG. 3 concrete prepared in example 1 and having a strain rate of 10-5s-1Tensile stress-strain curve.
FIG. 4 example 1 preparationTo concrete at a strain rate of 10-4s-1Tensile stress-strain curve.
FIG. 5 concrete prepared in example 1 and having a strain rate of 10-3s-1Tensile stress-strain curve.
FIG. 6 concrete prepared in example 1 and having a strain rate of 10-2s-1Tensile stress-strain curve.
Detailed Description
The hydroxyethyl cellulose is selected from QP-300H series hydroxyethyl cellulose produced by Cellosize company; the polycarboxylic acid high-efficiency water reducing agent is selected from Viscocrete-540P series water reducing agents produced by Sika company; the antifoaming agent is selected from DF6352DD series antifoaming agent manufactured by AXILAT company; the inorganic gelling agent is prepared by a method of 'a pervious concrete gelling agent' in the patent technology of the granted publication No. CN 110304858B, and the preparation method of the embodiment 1 is specifically selected; the silica fume is purchased from platinum-based New materials science and technology limited; the mineral powder is purchased from platinum-lubricating new material science and technology limited; quartz sand was purchased from intelligence environmental protection ltd; the calcium carbonate crystal whisker is purchased from Shanghai pelargonium composite new material science and technology company Limited; PE fiber was purchased from a special rope reel, Splendid, model ZTD77, available from Dongguan.
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.
Example 1
The raw materials of the ultra-high ductility concrete comprise cement, silica fume, mineral powder, quartz sand, Polyethylene (PE) fiber, calcium carbonate whisker, polycarboxylic acid high-efficiency water reducing agent, hydroxyethyl cellulose, inorganic gelling agent, defoaming agent and water, all of which meet the requirements in the invention content, and are implemented according to the mixing ratio in Table 1.
TABLE 1 compounding ratio (kg/m) used in example 13Wherein the cement is P.O 52.5 type ordinary portland cement)
(1) Accurately weighing raw materials according to the mixing ratio shown in table 1 in the implementation process;
(2) mixing 20% water with calcium carbonate whisker and hydroxyethyl cellulose, and ultrasonically dispersing for 15min by using an integrated ultrasonic processor (brand: square demand, model: PZ-2000L) to obtain a material A;
(3) mixing a polycarboxylic acid high-efficiency water reducing agent and an inorganic gelling agent with 10% of water, and manually stirring at normal temperature for 3min at a stirring speed of 50 revolutions per minute to obtain a material B;
(4) mixing and stirring all cement, silica fume, mineral powder and quartz sand in a concrete horizontal mixer (a manufacturer: Hebeixin Namingshen instrument and equipment Co., Ltd., model: HJW-60) for 3min at a stirring speed of 70 r/min to obtain a material C;
(5) adding the rest water, and continuously stirring at normal temperature for 2min at the stirring speed of 70 r/min;
(6) adding the material A and the material B into the material obtained in the step (5), and continuing stirring at normal temperature for 3min, wherein the stirring speed is 70 r/min;
(7) then, adding all PE fibers, and continuing stirring at normal temperature for 15min, wherein the stirring speed is 70 r/min;
(8) and finally, adding all the defoaming agents, stirring at normal temperature for 2min, and stirring at the speed of 70 r/min to obtain the material of the embodiment.
Referring to JC/T2461-. Total test 10-5s-1、10-4s-1、10- 3s-1、10-2s-1Four strain rate parameters, 3 specimens per group.
The test effect of the embodiment is as follows: example at a strain rate of 10-5s-1、10-4s-1、10-3s-1And 10-2s-1Tensile stress-strain curves for the following tensile strength and ultimate tensile strength are shown in FIG. 3, FIG. 4, FIG. 5 and FIG. 6, respectivelyThe strain statistics are shown in table 2. By comparison, the PE-UHDC material provided by the invention has the advantages that the ultimate tensile strain does not decrease or increase reversely with the increase of the strain rate, and is composed of epsilon&＝1×10-5s-1The increase of 3.5% to ε&＝1×10-2s-16.2 percent of the time, is improved by 77.1 percent, so that the method solves the technical problem that the ultimate tensile strain of the PE-UHDC is reduced along with the increase of the strain rate, and can further give full play to the excellent anti-seismic performance of the PE-UHDC material and the structure.
Table 2 test results of example 1
Example 2
The raw materials used in this example were the same as in example 1, and the compounding ratios shown in Table 3 were used, and the preparation process and the test method were the same as in example 1.
TABLE 3 mixing ratio (kg/m) used in example 23Wherein the cement is P.O 52.5 type ordinary portland cement)
The test effect of the embodiment is as follows: example at a strain rate of 10-5s-1、10-4s-1、10-3s-1And 10-2s-1The tensile strength and ultimate tensile strain results are shown in table 4. By comparison, the PE-UHDC material provided by the embodiment also shows the tendency of no decrease and no reverse increase of the ultimate tensile strain along with the increase of the strain rate, wherein the tendency is shown by epsilon&＝1×10-5s-1The 1.6% increase in time is ε&＝1×10-2s-1The time is 2.7 percent, and the improvement is 68.7 percent. However, the strength and ultimate tensile strain of the PE-UHDC material provided by this example were lower than those of example 1.
Table 4 test results of example 2
Example 3
The raw materials used in this example were the same as in example 1, and the compounding ratios shown in Table 5 were used, and the preparation process and the test method were the same as in example 1.
TABLE 5 compounding ratio (kg/m) used in example 33Wherein the cement is P.O 52.5 type ordinary portland cement)
The test effect of the embodiment is as follows: example at a strain rate of 10-5s-1、10-4s-1、10-3s-1And 10-2s-1The tensile strength and ultimate tensile strain results are shown in table 6. By comparison, the PE-UHDC material provided by the embodiment also shows the tendency of no decrease and no reverse increase of the ultimate tensile strain along with the increase of the strain rate, wherein the tendency is shown by epsilon&＝1×10-5s-1The increase of 3.3% to ε&＝1×10-2s-1The time is 5.0 percent, and the improvement is 51.5 percent. Compared with example 1, the PE-UHDC material provided by the embodiment has lower strength and lower ultimate tensile strain, but is better than example 2.
Table 6 test results of example 3
When the selected components are in the range of the invention, the ultra-high ductility concrete material with the ultimate tensile strain not decreasing and reversely increasing along with the increase of the strain rate can be prepared according to the method in the invention, thereby fundamentally solving the technical problem that the ultimate tensile strain of PE-UHDC decreases along with the increase of the strain rate.
Example 4
The preparation and testing of the concrete was carried out as follows, using the raw materials of example 1 and the proportions indicated in table 1.
(1) Accurately weighing raw materials according to the mixing ratio shown in table 1 in the implementation process;
(2) mixing and stirring all cement, silica fume, mineral powder and quartz sand in a concrete horizontal mixer (manufacturer: Hebeixin Namingshen instrument and equipment Co., Ltd., model: HJW-60) for 3min at a stirring speed of 70 r/min;
(3) adding all water, calcium carbonate crystal whiskers, hydroxyethyl cellulose, a polycarboxylic acid water reducing agent and an inorganic gelling agent, and continuously stirring at normal temperature for 2min, wherein the stirring speed is 70 r/min;
(4) then, adding all PE fibers, and continuing stirring at normal temperature for 15min, wherein the stirring speed is 70 r/min;
(5) and finally, adding all the defoaming agents, stirring at normal temperature for 2min, and stirring at the speed of 70 r/min to obtain the material in the comparative example 3.
The test method of example 4 was the same as example 1. Test effects of example 4: this example has a strain rate of 10-5 s-1、10-4 s-1、10-3 s-1And 10-2 s-1The tensile strength and ultimate tensile strain results are shown in table 7. By comparison, the PE-UHDC material provided by the embodiment can show the trend of no decrease and no reverse increase of the ultimate tensile strain along with the increase of the strain rate, but the effect is not very obvious, and only the epsilon&＝1×10-5 s-12.9% increase to ε&＝1×10-2 s-1The time is 3.4 percent, and the improvement is 17.2 percent. Compared with example 1, the strength and ultimate tensile strain of the PE-UHDC material provided by the present example are very low, which shows that the preparation process has a very significant influence on the performance of the PE-UHDC material of the present invention.
Table 7 test results of example 4
Comparative example 1
The comparative example selects cement, silica fume, mineral powder, quartz sand, Polyethylene (PE) fiber, polycarboxylic acid high-efficiency water reducing agent, inorganic gelling agent, defoaming agent and water as raw materials, all the raw materials meet the requirements in the invention content, and the mixing proportion is implemented according to the table 8.
TABLE 8 compounding ratio (kg/m) used in comparative example 13Wherein the cement is P.O 52.5 type ordinary portland cement)
(1) Accurately weighing the raw materials according to the mixing ratio shown in the table 8 in the implementation process;
(2) mixing a polycarboxylic acid high-efficiency water reducing agent and an inorganic gelling agent with 10% of water, and manually stirring at normal temperature for 3min at a stirring speed of 50 revolutions per minute to obtain a material A;
(3) mixing and stirring all cement, silica fume, mineral powder and quartz sand in a concrete horizontal mixer (manufacturer: Hebeixin Namingshen instrument and equipment Co., Ltd., model: HJW-60) for 3min at a stirring speed of 70 r/min;
(4) adding the rest water, and continuously stirring at normal temperature for 2min at the stirring speed of 70 r/min;
(5) adding the material A into the material obtained in the step (4), and continuing stirring at normal temperature for 3min, wherein the stirring speed is 70 r/min;
(6) then, adding all PE fibers, and continuing stirring at normal temperature for 15min, wherein the stirring speed is 70 r/min;
(7) and finally, adding all the defoaming agents, stirring at normal temperature for 2min, and stirring at the speed of 70 r/min to obtain the material in the comparative example 1.
The test method of comparative example 1 was the same as example 1. This comparative example had a strain rate of 10-5s-1、10-4s-1、10-3s-1And 10-2s-1The tensile strength and ultimate tensile strain results are shown in table 9. By comparison, it can be seen that the PE-UHDC material provided by the comparative example shows a decreasing trend of the ultimate tensile strain with the increasing strain rate, which is represented by epsilon&＝1×10-5s-12.8% reduction to ε&＝1×10-2s-1The proportion is 1.9 percent, and is reduced by 32.1 percent, which shows that the tensile ductility of the UHDC material prepared by singly using the PE fiber has obvious rate effect, which obviously does not facilitate the material to more fully exert the excellent shock resistance.
Table 9 test results of comparative example 1
Comparative example 2
The comparative example selects cement, silica fume, mineral powder, quartz sand, calcium carbonate whisker, polycarboxylic acid high-efficiency water reducing agent, hydroxyethyl cellulose, inorganic gelling agent, defoaming agent and water as raw materials, all the raw materials meet the requirements in the claims, and the operation is carried out according to the mixing ratio in the table 10.
TABLE 10 compounding ratio (kg/m) used in comparative example 23Wherein the cement is P.O 52.5 type ordinary portland cement)
(1) Accurately weighing the raw materials according to the mixing ratio shown in the table 10 in the implementation process;
(2) mixing 20% water with calcium carbonate whisker and hydroxyethyl cellulose, and ultrasonically dispersing for 15min by using an integrated ultrasonic processor (brand: square demand, model: PZ-2000L) to obtain a material A;
(3) mixing a polycarboxylic acid high-efficiency water reducing agent and an inorganic gelling agent with 10% of water, and manually stirring at normal temperature for 3min at a stirring speed of 50 revolutions per minute to obtain a material B;
(4) mixing and stirring all cement, silica fume, mineral powder and quartz sand in a concrete horizontal mixer (a manufacturer: Hebeixin Namingshen instrument and equipment Co., Ltd., model: HJW-60) for 3min at a stirring speed of 70 r/min to obtain a material C;
(5) adding the rest water, and continuously stirring at normal temperature for 2min at the stirring speed of 70 r/min;
(6) adding the material A and the material B into the material obtained in the step (5), and continuing stirring at normal temperature for 3min, wherein the stirring speed is 70 r/min;
(7) and finally, adding all the defoaming agents, stirring at normal temperature for 2min at the stirring speed of 70 r/min to obtain the material of the comparative example 2.
The test method of comparative example 2 was the same as example 1. Test effects of comparative example 2: this comparative example had a strain rate of 10-5s-1、10-4s-1、10-3s-1And 10-2s-1The tensile strength and ultimate tensile strain results are shown in table 10. As can be seen by comparison, the calcium carbonate whisker reinforced cement-based composite material provided by the comparative example shows a remarkable reduction trend of the ultimate tensile strain along with the increase of the strain rate, wherein the strain rate is represented by epsilon&＝1×10-5s-10.062% reduction to ε&＝1×10-2s-1The 0.037% drop by 40.3% indicates that the tensile ductility of cement-based materials formulated with calcium carbonate whiskers and inorganic gelling agents also had a significant rate effect.
Table 10 test results of comparative example 2
Comparative example 3
The comparative example selects cement, silica fume, mineral powder, quartz sand, polycarboxylic acid high-efficiency water reducing agent, hydroxyethyl cellulose, inorganic gelling agent, defoaming agent and water as raw materials, all the raw materials meet the requirements in the claims, and the operation is carried out according to the mixing ratio in the table 11.
TABLE 11 compounding ratio (kg/m) used in comparative example 33Wherein the cement is P.O 52.5 type ordinary portland cement)
(1) Accurately weighing the raw materials according to the mixing ratio shown in Table 11 in the implementation process;
(2) mixing a polycarboxylic acid high-efficiency water reducing agent and an inorganic gelling agent with 10% of water, and manually stirring at normal temperature for 3min at a stirring speed of 50 revolutions per minute to obtain a material A;
(3) mixing and stirring all cement, silica fume, mineral powder and quartz sand in a concrete horizontal mixer (a manufacturer: Hebeixin Namingshen instrument and equipment Co., Ltd., model: HJW-60) for 3min at a stirring speed of 70 r/min to obtain a material B;
(4) adding the rest of water into the material B, and continuously stirring for 2min at normal temperature, wherein the stirring speed is 70 r/min;
(5) adding the material A into the material obtained in the step (4), and continuing stirring at normal temperature for 3min, wherein the stirring speed is 70 r/min;
(6) and finally, adding all the defoaming agents, stirring at normal temperature for 2min, and stirring at the speed of 70 r/min to obtain the material in the comparative example 3.
The test method of comparative example 3 was the same as example 1. Test effects of comparative example 3: this comparative example had a strain rate of 10-5s-1、10-4s-1、10-3s-1And 10-2s-1The tensile strength and ultimate tensile strain results are shown in table 12. As can be seen by comparison, the cement-based composite material provided by the comparative example shows a remarkable decrease trend of the ultimate tensile strain along with the increase of the strain rate, wherein the decrease trend is represented by epsilon&＝1×10-5s-10.054% of the time is reduced to epsilon&＝1×10-2s-1The 0.031% drop by 42.6% indicates that the tensile ductility of the cement-based material formulated with the inorganic gelling agent alone also has a significant rate effect.
Table 12 test results of comparative example 3
Comparative example 4
The comparative example selects cement, silica fume, mineral powder, quartz sand, ultra-short cut PE fiber, calcium carbonate whisker, polycarboxylic acid high-efficiency water reducing agent, hydroxyethyl cellulose, defoaming agent and water as raw materials, all the raw materials meet the requirements in the claims, and the mixing proportion is implemented according to the table 13.
TABLE 13 compounding ratio (kg/m) used in comparative example 43Wherein the cement is P.O 52.5 type ordinary portland cement)
(1) Accurately weighing the raw materials according to the mixing ratio shown in Table 13 in the implementation process;
(2) mixing 20% water with calcium carbonate whisker and hydroxyethyl cellulose, and ultrasonically dispersing for 15min by using an integrated ultrasonic processor (brand: square demand, model: PZ-2000L) to obtain a material A;
(3) mixing the polycarboxylic acid high-efficiency water reducing agent with 10% of water, and manually stirring at normal temperature for 3min at a stirring speed of 50 rpm to obtain a material B;
(4) mixing and stirring all cement, silica fume, mineral powder and quartz sand in a concrete horizontal mixer (a manufacturer: Hebeixin Namingshen instrument and equipment Co., Ltd., model: HJW-60) for 3min at a stirring speed of 70 r/min to obtain a material C;
(5) adding the rest water, and continuously stirring at normal temperature for 2min at the stirring speed of 70 r/min;
(6) adding the material A and the material B into the material obtained in the step (5), and continuing stirring at normal temperature for 3min, wherein the stirring speed is 70 r/min;
(7) then, adding all PE fibers, and continuing stirring at normal temperature for 15min, wherein the stirring speed is 70 r/min;
(8) and finally, adding all the defoaming agents, stirring at normal temperature for 2min, and stirring at the speed of 70 r/min to obtain the material of the comparative example 4.
The test method of comparative example 4 was the same as example 1. Test effects of comparative example 4: this comparative example had a strain rate of 10-5s-1、10-4s-1、10-3s-1And 10-2s-1The tensile strength and ultimate tensile strain results are shown in table 14. As can be seen by comparison, the high ductility cement-based composite material provided by the comparative example has an ultimate tensile strain dependentThe increase in strain rate showed a slight decrease in strain rate, from ε&＝1×10-5s-1The 3.1% reduction to ε&＝1×10-2s-1The time is reduced by 19.4% by 2.5%, which shows that the high-ductility cement-based composite material prepared by the method has a certain rate effect on the tensile ductility.
Table 14 test results of comparative example 4
Although the present invention has been described with reference to the preferred embodiments, it should be understood that various changes and modifications can be made therein by those skilled in the art without departing from the spirit and scope of the invention as defined in the appended claims.
Claims (9)
1. The ultra-high ductility concrete for earthquake-resistant engineering is characterized by comprising the following components in parts by weight:
the dosage of the components is kg/m3
400-450% of cement
Silica fume 375-430
350-420 parts of mineral powder
Quartz sand 450-550
PE fiber 9.7-19.4
7.15-28.6 calcium carbonate whiskers
5.6-13.4 parts of water reducing agent
0.12 to 0.18% of hydroxyethyl cellulose
10-15 parts of inorganic gelling agent
0.1-0.15% of defoaming agent
225-280 parts of water;
the preparation method comprises the following steps:
(1) weighing raw materials in proportion;
(2) mixing and dispersing 10-20% of water, calcium carbonate whiskers and hydroxyethyl cellulose to obtain a calcium carbonate whisker dispersion suspension;
(3) mixing a polycarboxylic acid high-efficiency water reducing agent and an inorganic gelling agent with 5-10% of water;
(4) mixing and stirring cement, silica fume, mineral powder and quartz sand;
(5) adding the rest water into the material obtained in the step (4), and mixing and stirring;
(6) adding the materials obtained in the step (2) and the step (3) into the material obtained in the step (5), and mixing and stirring;
(7) adding PE fibers into the material obtained in the step (6), and mixing and stirring;
(8) adding a defoaming agent into the material obtained in the step (7), and mixing and stirring to obtain the ultra-high ductility concrete;
wherein, the sequence among the step (2), the step (3) and the steps (4) - (5) can be changed or carried out simultaneously;
the inorganic gelling agent is synthesized by a patent technology of a pervious concrete gelling agent of an authorized publication number CN 110304858B.
2. The ultra-high ductility concrete according to claim 1, wherein the cement comprises any one of portland cement, ordinary portland cement, portland slag cement, pozzolanic portland cement, portland fly ash cement, or composite portland cement.
3. The ultra-high ductility concrete as claimed in claim 1 or 2, wherein the silica fume has a silica content of not less than 96% by mass, an average particle diameter of 0.05 to 0.2 μm, and a specific surface area of not less than 17000m2/kg。
4. The ultra-high ductility concrete as claimed in claim 1, whereinCharacterized in that the activity index of the mineral powder in 28 days is not less than 105 percent, and the specific surface area is not less than 500m2/kg。
5. The ultra-high ductility concrete as claimed in claim 1, wherein the PE fiber has a diameter of 20 to 40 μm, a length of 6 to 15mm, and a tensile strength of not less than 3000 MPa.
6. The ultra-high ductility concrete as claimed in claim 1, wherein the calcium carbonate whiskers have a diameter of 0.5 to 2 μm, a length of 20 to 30 μm, and an elastic modulus of 410 to 710 GPa.
7. The ultra-high ductility concrete as claimed in claim 1, wherein the dispersion method in the step (2) is ultrasonic dispersion, the ultrasonic frequency is 19 to 26kHz, and the ultrasonic time is 10 to 15 min.
8. The ultra-high ductility concrete according to claim 1, wherein in the step (3), the water reducing agent and the inorganic gelling agent are stirred for 3-5 min at a stirring speed of 50-70 r/min in the process of stirring and mixing with 5% -10% of water.
9. Use of the ultra-high ductility concrete according to any one of claims 1 to 8 in the field of construction.
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| CN113754383B (en) * | 2021-10-13 | 2022-07-05 | 昭通市宜昭高速公路投资开发有限公司 | Bendable concrete and preparation method thereof |
| CN114477904A (en) * | 2022-02-16 | 2022-05-13 | 中国建筑科学研究院有限公司 | Cement-based high-ductility anti-seismic material for anti-seismic reconstruction of village and town buildings and preparation method thereof |
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