CN113443878A - Ultra-high performance concrete hollow slab and preparation method thereof - Google Patents

Ultra-high performance concrete hollow slab and preparation method thereof Download PDF

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Publication number
CN113443878A
CN113443878A CN202110836329.1A CN202110836329A CN113443878A CN 113443878 A CN113443878 A CN 113443878A CN 202110836329 A CN202110836329 A CN 202110836329A CN 113443878 A CN113443878 A CN 113443878A
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ultra
high performance
performance concrete
parts
hollow slab
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夏春蕾
李宇容
李世元
任成传
王贯明
张磊
赵志刚
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Beijing Yantong Precast Concrete Co ltd
Beijing Municipal Engineering Research Institute
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Beijing Yantong Precast Concrete Co ltd
Beijing Municipal Engineering Research Institute
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    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B28/00Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
    • C04B28/02Compositions 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
    • C04B28/04Portland cements
    • CCHEMISTRY; METALLURGY
    • C04CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04BLIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B40/00Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
    • C04B40/04Preventing evaporation of the mixing water
    • EFIXED CONSTRUCTIONS
    • E04BUILDING
    • E04BGENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
    • E04B5/00Floors; Floor construction with regard to insulation; Connections specially adapted therefor
    • E04B5/02Load-carrying floor structures formed substantially of prefabricated units
    • E04B5/04Load-carrying floor structures formed substantially of prefabricated units with beams or slabs of concrete or other stone-like material, e.g. asbestos cement
    • E04B5/043Load-carrying floor structures formed substantially of prefabricated units with beams or slabs of concrete or other stone-like material, e.g. asbestos cement having elongated hollow cores

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  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Structural Engineering (AREA)
  • Architecture (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
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  • Inorganic Chemistry (AREA)
  • Curing Cements, Concrete, And Artificial Stone (AREA)

Abstract

The invention provides an ultra-high performance concrete hollow slab and a preparation method thereof, belonging to the technical field of concrete members. The invention provides a ground ultra-high performance concrete hollow slab which is of a totally-enclosed structure, wherein the outer wall of the ultra-high performance concrete hollow slab is formed by ultra-high performance concrete, and the inner part of the ultra-high performance concrete hollow slab is a foam slab; the ultra-high performance concrete comprises the following components in parts by weight: 25 parts of silicate 42.5R cement; 5 parts of silica fume; 5 parts of fly ash micro-beads; 22 parts of medium sand; 25 parts of fine sand; 5 parts of steel fiber; 6 parts of water; 0.7 part of water reducing agent; 0.8 part of anti-cracking toughening agent; 0.25 part of defoaming agent. The hollow slab provided by the invention has the characteristics of high strength, good durability and light weight. The results of the examples show that the hollow slab has the breaking strength of 19.2MPa and the splitting tensile strength of 15.6MPa, and the weight reduction rate is over 60 percent compared with a solid concrete slab.

Description

Ultra-high performance concrete hollow slab and preparation method thereof
The application is a divisional application of Chinese patent application with the application number of CN201811609452.4, the name of which is 'an ultra-high performance concrete and an ultra-high performance concrete hollow slab and a preparation method thereof' filed in 2018, 12 months and 27 days.
Technical Field
The invention belongs to the technical field of concrete members, and particularly relates to an ultrahigh-performance concrete hollow slab and a preparation method thereof.
Background
Buildings assembled from prefabricated parts at the site are called fabricated buildings. With the great support of the country for the fabricated building in recent years, the occupation ratio of the fabricated building in the building is greatly improved. A large number of building parts of the fabricated building are produced and processed by workshops, and the types of components mainly comprise: external wall panels, internal wall panels, laminated slabs, balcony/balcony partitions, air-conditioning panels, stairs, prefabricated beams, prefabricated columns and the like. In which the balcony partition mainly serves as a decoration and partition, but the weight thereof is extremely critical since it is located on a balcony, the lower part of which is unsupported. And the balcony baffle that adopts ordinary concrete prefabrication is lower because of its intensity especially bending strength for the extremely heaviness of this type baffle design is unfavorable for the balcony bearing.
In recent years, ultra-high performance concrete materials gradually show the corner in the field of constructional engineering, and because of the ultra-high bending strength and bending strength of the ultra-high performance concrete, a large partition which is thinner and lighter than conventional concrete becomes possible. However, the existing ultrahigh-performance concrete has high viscosity and poor fluidity, is difficult to freely flow in a pouring gap between moulds, and is easy to cause defects and cavities in the pouring process; secondly, the surface of the existing ultra-high performance concrete is easy to air-dry and crust after being poured, the operable time of the surface is only 1 hour, and the final setting time is more than 6 hours, so that the surface of the hollow slab cannot be smoothly collected in the later period like common concrete. Therefore, the ultra-high performance concrete members currently on the market are generally of the solid plate type.
Disclosure of Invention
The invention aims to provide an ultra-high performance concrete hollow slab and a preparation method thereof, and the ultra-high performance concrete adopted by the invention has good fluidity, so that the ultra-high performance concrete hollow slab can be used for pouring the hollow slab; the preparation method of the hollow slab can realize smooth surface folding of the ultrahigh concrete.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides an ultra-high performance concrete hollow slab, which is of a fully closed structure, wherein the outer wall of the ultra-high performance concrete hollow slab is formed by ultra-high performance concrete, and the inner part of the ultra-high performance concrete hollow slab is a foam slab;
the ultra-high performance concrete comprises the following components in parts by weight: 25 parts of silicate 42.5R cement; 5 parts of silica fume; 5 parts of fly ash micro-beads; 22 parts of medium sand; 25 parts of fine sand; 5 parts of steel fiber; 6 parts of water; 0.7 part of water reducing agent; 0.8 part of anti-cracking toughening agent; 0.25 part of defoaming agent; the water reducing agent is a polycarboxylic acid water reducing agent, and the water reducing rate is 40%;
the particle size of the fly ash micro-beads is 1-100 mu m; the content of the micro-beads in the fly ash micro-beads is more than 75 wt%, and the water demand ratio is less than 96%;
the grain diameter of the medium sand is [20,40] meshes, and the grain diameter of the fine sand is (40,80] meshes.
Preferably, the thickness of the outer wall is 2-3 cm, and the thickness of the foam plate is 10-20 cm.
Preferably, the length of the steel fiber is 15-17 mm, and the diameter of the steel fiber is 0.18-0.22 mm.
Preferably, the anti-cracking toughening agent is a silicone-acrylic emulsion, and the solid content of the silicone-acrylic emulsion is 50-60%.
The invention provides a preparation method of the ultra-high performance concrete hollow slab, which comprises the following steps:
assembling the outer templates to obtain outer template cavities;
fixing the foam board in the cavity of the outer template, and forming a pouring gap between the outer template and the foam board;
pouring the ultrahigh-performance concrete into a gap between the outer template and the foam board, spraying an anti-evaporation agent on a pouring surface, and performing surface folding treatment to obtain a hollow primary blank; the evaporation reducing agent is a sodium stearate surfactant with the solid content of 5%;
and (4) after the hollow primary blank is subjected to steam curing, removing the outer template to obtain the ultra-high performance concrete hollow slab.
Preferably, before assembling the outer formworks, the method further comprises the step of coating a release agent on the outer formworks.
Preferably, before the steam curing, the hollow slab after the surface folding is kept still for 8-12 hours.
Preferably, the spraying amount of the evaporation reducing agent is 0.8-1.2 kg/m2
Preferably, the steam curing temperature is 50-60 ℃, and the time is 40-50 h.
Preferably, the mode that the foam board is fixed inside the outer formwork comprises: and placing a steel plate or a wood plate at the exposed end of the foam plate, and fixing the steel plate or the wood plate.
The invention provides a hollow slab, which is of a fully-closed structure, wherein the outer wall of the hollow slab is made of ultra-high performance concrete, the inner part of the hollow slab is made of a foam slab, and the ultra-high performance concrete comprises the following components in parts by weight: 20-30 parts of Portland cement; 3-8 parts of silica fume; 3-8 parts of fly ash microbeads; 20-30 parts of medium sand; 20-30 parts of fine sand; 4-7 parts of steel fiber; 5-7 parts of water; 0.5-1 part of a water reducing agent; 0.5-1 part of anti-cracking toughening agent; 0.5-1 part of a defoaming agent; the water reducing rate of the water reducing agent is more than 35%. The gap of the ultra-high performance concrete is minimized, so that the extrusion of water in the gap is facilitated, and the fluidity of the concrete is improved; in addition, the fly ash micro-beads are adopted to replace fly ash, the particles of the fly ash micro-beads are relatively round and smooth, the ball effect is achieved, the viscosity of the ultra-high performance concrete can be greatly reduced, and the fluidity of the ultra-high performance concrete is improved; in addition, the invention adopts the water reducing agent with higher water reducing rate, and controls the addition amount of the water reducing agent in the range, so that more released water is released, and the fluidity of the concrete is improved. The hollow slab provided by the invention has the characteristics of high strength, good durability and light weight. The results of the examples show that the hollow slab has the breaking strength of 19.2MPa and the splitting tensile strength of 15.6MPa, and the weight reduction rate is over 60 percent compared with a solid concrete slab.
The invention also provides a preparation method of the hollow slab in the technical scheme, and the anti-evaporation agent is sprayed on the casting surface, so that the water evaporation of the casting surface can be inhibited, the surface is prevented from being rapidly skinned, the smooth surface folding is realized, and the hollow ultra-thin-wall ultra-high performance concrete member is successfully obtained.
Drawings
FIG. 1 is a schematic view showing the construction of an ultra high performance concrete core slab according to the present invention,
wherein, 1-foam board, 2-outer wall;
FIG. 2 is a photograph of a cross section of an ultra high performance concrete hollow core slab of example 3.
Detailed Description
The invention provides an ultra-high performance concrete, which comprises the following components in parts by weight:
Figure BDA0003177190440000031
the water reducing rate of the water reducing agent is more than 35%.
In the present invention, each component is a commercially available product without specific description.
The ultra-high performance concrete provided by the invention comprises 20-30 parts by weight of portland cement, preferably 22-27 parts by weight, and more preferably 25 parts by weight. In the present invention, the portland cement is preferably 42.5R cement.
Based on the weight part of the Portland cement, the ultra-high performance concrete provided by the invention comprises 3-8 parts of silica fume, preferably 4-7 parts, and more preferably 5 parts. In the invention, the average particle size of the silica fume is preferably 0.1-0.3 μm, and the content of silicon dioxide in the silica fume is more than 92 wt.%.
Based on the weight parts of the portland cement, the ultrahigh-performance concrete provided by the invention comprises 3-8 parts of fly ash microbeads, preferably 4-7 parts, and more preferably 5 parts. In the invention, the particle size of the fly ash micro-beads is preferably 1-100 μm, more preferably 10-85 μm, and more preferably 20-70 μm; the content of the microbeads in the fly ash microbeads is preferably more than 75 wt.%, and more preferably more than 80 wt.%; the water demand ratio of the fly ash microbeads is preferably less than 96%, more preferably 94-95%, and most preferably 94%. The invention adopts the fly ash micro-beads to replace fly ash, the particles of the fly ash micro-beads are relatively round and smooth, the fly ash micro-beads have a ball effect, the viscosity of the ultra-high performance concrete can be greatly reduced, the fluidity of the ultra-high performance concrete is improved, and the ultra-high performance concrete can be further used for pouring hollow slabs.
Based on the weight part of the Portland cement, the ultrahigh-performance concrete provided by the invention comprises 20-30 parts of medium sand, preferably 21-26 parts of medium sand, and more preferably 22 parts of medium sand. In the present invention, the particle size of the medium sand is preferably [20,40] mesh. In the invention, the medium sand is preferably quartz sand or river sand; the silica content of the medium sand is preferably greater than 95 wt.%.
Based on the weight part of the Portland cement, the ultra-high performance concrete provided by the invention comprises 20-30 parts of fine sand, preferably 21-26 parts, and more preferably 25 parts. In the present invention, the fine sand preferably has a particle size of (40, 80) mesh, and in the present invention, the fine sand preferably is quartz sand or river sand, and the content of silica in the fine sand is preferably more than 95 wt.%.
Based on the weight parts of the Portland cement, the ultrahigh-performance concrete provided by the invention comprises 4-7 parts of steel fibers, preferably 5-6 parts, and more preferably 5 parts. In the invention, the length of the steel fiber is preferably 15-17 mm, and the diameter of the steel fiber is preferably 0.18-0.22 mm; the steel fibers are preferably straight fibers or end hook fibers.
Based on the weight part of the Portland cement, the ultra-high performance concrete provided by the invention comprises 5-7 parts of water, preferably 6-7 parts, and more preferably 6 parts. The source of the water is not particularly required in the present invention, and water of a source well known to those skilled in the art can be used.
Based on the weight portion of the portland cement, the ultrahigh-performance concrete provided by the invention comprises 0.5-1 part of a water reducing agent, preferably 0.6-0.9 part, and more preferably 0.7 part. In the invention, the water reducing rate of the water reducing agent is more than 35%, preferably 35-40%. In the present invention, the water reducing agent is preferably a polycarboxylic acid water reducing agent. The invention adopts the water reducing agent with higher water reducing rate, and controls the addition amount of the water reducing agent in the range, so that more released water is released, the fluidity of the concrete is further improved, and the ultrahigh-performance concrete can be used for pouring the hollow slab.
Based on the weight parts of the Portland cement, the ultrahigh-performance concrete provided by the invention comprises 0.5-1 part of anti-cracking toughening agent, preferably 0.7-0.9 part, and more preferably 0.8 part. In the invention, the anti-cracking toughening agent is preferably silicone-acrylic emulsion; the solid content of the silicone-acrylate emulsion is preferably 50-60%, and more preferably 55%.
Based on the weight part of the Portland cement, the ultra-high performance concrete provided by the invention comprises 0.2-0.3 part of defoaming agent, and preferably 0.25 part. In the present invention, the antifoaming agent is preferably P803.
The components and the proportion are adopted, so that the gap of the ultra-high performance concrete is minimized, the extrusion of water in the gap is facilitated, and the fluidity of the concrete is improved.
The preparation method of the ultra-high performance concrete has no special requirements, and all the components are directly and uniformly mixed.
As shown in fig. 1, the invention also provides an ultra-high performance concrete hollow slab, which is a fully closed structure, wherein the outer wall 2 of the ultra-high performance concrete hollow slab is formed by molding the ultra-high performance concrete according to the technical scheme, and the inner part of the ultra-high performance concrete hollow slab is a foam slab 1.
In the invention, the thickness of the outer wall of the ultra-high performance concrete hollow slab is preferably 2-3 cm, and the thickness of the foam slab is preferably 10-20 cm, and more preferably 20 cm. The length and width of the hollow board are not particularly limited in the present invention, and the length and width of the board known to those skilled in the art can be adopted. In a specific embodiment of the invention, the length of the ultra-high performance concrete hollow slab is 230cm, the width is 105cm, and the thickness is 25 cm; the inner foam panels had a length of 225cm, a width of 100cm and a thickness of 20 cm. The hollow slab of the invention is not an actual hollow structure, but the concrete in the concrete solid slab is replaced by the foam slab, and the interior formed by the solid concrete slab is a closed slab of the foam slab.
The invention also provides a preparation method of the ultra-high performance concrete hollow slab, which comprises the following steps:
assembling the outer templates to obtain outer template cavities;
fixing the foam board in the cavity of the outer template, and forming a pouring gap between the outer template and the foam board;
pouring the ultrahigh-performance concrete into a gap between the outer template and the foam board, spraying an anti-evaporation agent on a pouring surface, and performing surface folding treatment to obtain a hollow primary blank;
and (4) after the hollow primary blank is subjected to steam curing, removing the external mold to obtain the ultra-high performance concrete hollow slab.
The outer formwork is assembled to obtain the outer formwork cavity.
In the present invention, the outer form is preferably a steel form. The invention has no special requirements on the source of the steel template, and the steel template known by the technical personnel in the field can be adopted. The invention has no special requirements on the assembling mode, and the assembling mode known by the technicians in the field can be adopted. In the invention, the bottom and the periphery of the outer formwork cavity are surrounded by the outer formwork, and the top of the outer formwork cavity is in an open and exposed state, so that the foam board is conveniently placed in the outer formwork cavity and concrete is poured, and the outer formwork cavity obtained after assembly corresponds to the outer contour of the hollow board.
The present invention preferably further comprises applying a release agent to the outer formworks prior to assembling the outer formworks. The invention has no special requirements on the type of the release agent, and the release agent known to a person skilled in the art can be adopted. The invention has no special requirement on the brushing amount of the release agent, and the brushing amount known by the technical personnel in the field can be adopted.
After the outer formwork cavity is obtained, the foam board is fixed in the outer formwork cavity, and a pouring gap is formed between the outer formwork and the foam board; in the present invention, the outer wall of the outer formwork cavity is preferably not in contact with the foam slab, so that casting voids are formed around the foam slab.
In the invention, the thickness of the foam plate is preferably 10-20 cm, and more preferably 20 cm. The foam board plays a role of internal filling and also plays a role of an internal template. The pouring gap between the foam board and the outer template is preferably ensured through the four-corner gasket. In the invention, the four-corner gaskets are uniformly distributed on one side opposite to the exposed end of the foam board, and the interval between every two adjacent four-corner gaskets is preferably 38-42 cm. In the invention, the pouring gap is used for subsequently pouring the ultra-high performance concrete, thereby forming the outer wall of the hollow slab. In the present invention, the fixing manner of the foam board in the cavity of the outer formwork preferably includes: and placing a steel plate or a wood plate at the exposed end of the foam plate, and fixing the steel plate or the wood plate. In the present invention, the length of the steel or wood plate is preferably the same as the length of the foam board, and the width of the steel or wood plate is preferably the same as the width of the foam board. The present invention preferably fixes the steel plate or the wood plate by pressing it with a fixing member mounted on the outer mold. According to the invention, the steel plate or the wood plate which is as long as the foam plate is placed on the foam plate, so that the foam plate can be prevented from floating upwards in the pouring process, and the smooth pouring of the hollow plate is further ensured.
The present invention preferably further comprises installing embedments on the outer form prior to securing the foam board within the outer form. The invention has no special requirements on the shape and the installation mode of the embedded part, and the embedded part with the shape and the installation mode which are well known by the technicians in the field can be adopted.
After the pouring gap is formed, the ultra-high performance concrete is poured into the gap between the outer template and the foam board to form a pouring surface. The invention has no special requirements on the pouring mode of the ultrahigh-performance concrete, and the pouring mode known by the technicians in the field can be adopted. After a pouring surface is formed, the invention sprays the anti-steaming agent on the pouring surface, and carries out surface folding treatment to obtain a hollow primary blank.
In the present invention, the evaporation reducing agent is preferably a sodium stearate surfactant with a solid content of 5%. In the invention, the spraying amount of the evaporation reducing agent is preferably 0.8-1.2 kg/m2More preferably 1kg/m2. The invention has no special requirement on the spraying mode of the anti-evaporation agent, and the spraying mode known by the technicians in the field can be adopted. According to the invention, the evaporation reducing agent is sprayed on the casting surface, so that the evaporation of water on the casting surface can be inhibited, the surface is prevented from being rapidly skinned, and the smooth surface recovery is realized. In the invention, the pouring surface refers to the surface of the ultra-high performance concrete exposed after pouring, namely the surface not contacted with the template.
After the hollow primary blank is obtained, the invention carries out steam curing on the hollow primary blank. In the invention, the steam curing temperature is preferably 50-60 ℃, and more preferably 55 ℃; the steam curing time is preferably 40-50 h, and more preferably 48 h.
Before the steam curing, the method preferably further comprises the step of standing the cast blank after the surface is collected for 8-12 hours. According to the invention, the cast blank after being collected is kept stand for 8-12 h to obtain a hollow primary blank, and then steam curing is carried out, so that the self-growth of the early strength of concrete can be ensured, and the hollow slab uplift caused by too fast evaporation of water in the hollow slab can be avoided.
After steam curing, the outer formwork is dismantled, and the ultra-high performance concrete hollow slab is obtained. The invention has no special requirement on the dismounting mode of the outer template, and the dismounting mode known by the technicians in the field can be adopted.
The ultra-high performance concrete hollow slab and the method for manufacturing the same according to the present invention will be described in detail with reference to the following examples, which should not be construed as limiting the scope of the present invention.
Example 1
The ultra-high performance concrete comprises the following components in parts by weight: 25 parts of silicate 42.5R cement; 5 parts of silica fume; 5 parts of fly ash micro-beads; 22 parts of medium sand; 25 parts of fine sand; 5 parts of steel fiber; 6 parts of water; 0.7 part of water reducing agent; 0.8 part of anti-cracking toughening agent; 0.25 part of defoaming agent; the water reducing agent is a polycarboxylic acid water reducing agent, and the water reducing rate is 40%.
Example 2
The ultra-high performance concrete comprises the following components in parts by weight: 22 parts of silicate 42.5R cement; 6 parts of silica fume; 7 parts of fly ash microbeads; 22 parts of medium sand; 25 parts of fine sand; 5 parts of steel fiber; 6 parts of water; 0.7 part of water reducing agent; 0.8 part of anti-cracking toughening agent; 0.25 part of defoaming agent; the water reducing agent is a polycarboxylic acid water reducing agent, and the water reducing rate is 40%.
Comparative example 1
The difference from the embodiment 1 is that the fly ash is used as a raw material;
the ultra-high performance concrete comprises the following components in parts by weight: 25 parts of silicate 42.5R cement; 5 parts of silica fume; 5 parts of fly ash; 22 parts of medium sand; 25 parts of fine sand; 5 parts of steel fiber; 6 parts of water; 0.7 part of water reducing agent; 0.8 part of anti-cracking toughening agent; 0.25 part of defoaming agent; the water reducing agent is a polycarboxylic acid water reducing agent, and the water reducing rate is 40%.
Comparative example 2
The difference from the example 1 lies in the water reducing rate of the water reducing agent;
the ultra-high performance concrete comprises the following components in parts by weight: 25 parts of silicate 42.5R cement; 5 parts of silica fume; 5 parts of fly ash micro-beads; 22 parts of medium sand; 25 parts of fine sand; 5 parts of steel fiber; 6 parts of water; 0.7 part of water reducing agent; 0.8 part of anti-cracking toughening agent; 0.25 part of defoaming agent; the water reducing agent is a polycarboxylic acid water reducing agent, and the water reducing rate is 30%.
Fluidity tests were performed on the ultra-high performance concrete of examples 1-2 and comparative examples 1-2, and the performance data obtained under the test conditions refer to GB/T50081-2002 Standard test methods for mechanical Properties of ordinary concrete, and are shown in Table 1.
TABLE 1 Performance of ultra high Performance concrete of examples 1-2 and comparative examples 1-2
Example 1 Example 2 Comparative example 1 Comparative example 2
Extension degree mm 720 720 640 620
As can be seen from the data in Table 1, the comparative example 1 adopts the ultra-high performance concrete obtained by using the fly ash as the raw material, and the expansibility is only 640 mm; the comparison document 2 adopts a water reducing agent with a low water reducing rate, and the obtained concrete has an expansion degree of 620 mm; the super-high performance concrete provided by the invention has the expansion degree of 720mm, which shows that the fluidity of the concrete is greatly improved by adopting the fly ash micro-beads to replace fly ash and adopting the water reducing agent with high water reducing rate.
Example 3
Preparing the ultra-high performance concrete hollow slab:
(1) firstly, coating a release agent on the steel external template, assembling, and then installing an embedded part for connecting the hollow plate on the steel template. And placing and fixing the cut foam inner die inside the outer die, and keeping the distance of 2-3 cm between the foam plate and the steel film through the four-corner gasket.
(2) And placing a steel plate on the upper part of the foam, wherein the steel plate is as long as the upper part of the foam, and then pressing the steel plate by using a fixing piece arranged on a die to prevent the foam plate from floating upwards.
(3) And then pouring the stirred ultrahigh-performance concrete in the embodiment 1 into a gap between the steel outer mold and the foam board, spraying an anti-steaming agent on a pouring surface after pouring, keeping the pouring surface wet, performing surface folding treatment, and performing steam curing after 12h to finally form the ultrahigh-performance concrete hollow board.
FIG. 2 is a photograph showing a cross section of an ultra high performance concrete hollow slab of example 3, wherein FIG. 2 shows that the inside of the hollow slab is a foam slab and the outside is ultra high performance concrete.
The performance test of the ultra-high performance concrete hollow slab obtained in the example 3 is carried out, the test standard is GB/T31387-2015 activated powder concrete, and the test result shows that the flexural strength of the hollow slab is 19.2MPa, the splitting tensile strength is 15.6MPa, and the weight reduction rate of the hollow slab is 60% compared with that of a solid slab cast by the ultra-high performance concrete.
According to the embodiments, the invention provides the ultra-high performance concrete hollow slab and the preparation method thereof, and the ultra-high performance concrete provided by the invention has good fluidity, so that the ultra-high performance concrete hollow slab can be used for pouring the hollow slab; the preparation method of the hollow slab can realize smooth surface folding of the ultrahigh concrete.
The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims (10)

1. The ultra-high performance concrete hollow slab is characterized in that the ultra-high performance concrete hollow slab is of a fully closed structure, the outer wall of the ultra-high performance concrete hollow slab is formed by ultra-high performance concrete, and the inner part of the ultra-high performance concrete hollow slab is a foam slab;
the ultra-high performance concrete comprises the following components in parts by weight: 25 parts of silicate 42.5R cement; 5 parts of silica fume; 5 parts of fly ash micro-beads; 22 parts of medium sand; 25 parts of fine sand; 5 parts of steel fiber; 6 parts of water; 0.7 part of water reducing agent; 0.8 part of anti-cracking toughening agent; 0.25 part of defoaming agent; the water reducing agent is a polycarboxylic acid water reducing agent, and the water reducing rate is 40%;
the particle size of the fly ash micro-beads is 1-100 mu m; the content of the micro-beads in the fly ash micro-beads is more than 75 wt%, and the water demand ratio is less than 96%;
the grain diameter of the medium sand is [20,40] meshes, and the grain diameter of the fine sand is (40,80] meshes.
2. The ultra-high performance concrete hollow slab as claimed in claim 1, wherein the thickness of the outer wall is 2-3 cm, and the thickness of the foam slab is 10-20 cm.
3. The ultra high performance concrete hollow core slab of claim 1, wherein the steel fiber has a length of 15 to 17mm and a diameter of 0.18 to 0.22 mm.
4. The ultra-high performance concrete hollow slab as claimed in claim 1, wherein the anti-cracking toughening agent is a silicone-acrylic emulsion, and the solid content of the silicone-acrylic emulsion is 50-60%.
5. The method for preparing the ultra-high performance concrete hollow slab as claimed in any one of claims 1 to 4, comprising the steps of:
assembling the outer templates to obtain outer template cavities;
fixing the foam board in the cavity of the outer template, and forming a pouring gap between the outer template and the foam board;
pouring the ultrahigh-performance concrete into a gap between the outer template and the foam board, spraying an anti-evaporation agent on a pouring surface, and performing surface folding treatment to obtain a hollow primary blank; the evaporation reducing agent is a sodium stearate surfactant with the solid content of 5%;
and (4) after the hollow primary blank is subjected to steam curing, removing the outer template to obtain the ultra-high performance concrete hollow slab.
6. The method of claim 5, further comprising applying a release agent to the outer form prior to assembling the outer form.
7. The preparation method of claim 5, further comprising standing the hollow slab after the surface is closed for 8-12 hours before the steam curing.
8. The method according to claim 5, wherein the amount of the evaporation reducing agent sprayed is 0.8 to 1.2kg/m2
9. The method according to claim 5 or 7, wherein the steam curing is performed at 50 to 60 ℃ for 40 to 50 hours.
10. The method for preparing the foam board according to claim 5, wherein the manner of fixing the foam board inside the outer template comprises: and placing a steel plate or a wood plate at the exposed end of the foam plate, and fixing the steel plate or the wood plate.
CN202110836329.1A 2018-12-27 2018-12-27 Ultra-high performance concrete hollow slab and preparation method thereof Pending CN113443878A (en)

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