CN115582902A - Preparation method of fireproof anti-cracking ultrahigh-performance concrete beam - Google Patents
Preparation method of fireproof anti-cracking ultrahigh-performance concrete beam Download PDFInfo
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B1/00—Producing shaped prefabricated articles from the material
- B28B1/50—Producing shaped prefabricated articles from the material specially adapted for producing articles of expanded material, e.g. cellular concrete
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B11/00—Apparatus or processes for treating or working the shaped or preshaped articles
- B28B11/24—Apparatus or processes for treating or working the shaped or preshaped articles for curing, setting or hardening
- B28B11/245—Curing concrete articles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B23/00—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects
- B28B23/02—Arrangements specially adapted for the production of shaped articles with elements wholly or partly embedded in the moulding material; Production of reinforced objects wherein the elements are reinforcing members
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28C—PREPARING CLAY; PRODUCING MIXTURES CONTAINING CLAY OR CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28C5/00—Apparatus or methods for producing mixtures of cement with other substances, e.g. slurries, mortars, porous or fibrous compositions
- B28C5/003—Methods for mixing
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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
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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
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/02—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by adding chemical blowing agents
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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
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/08—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by adding porous substances
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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
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/10—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by using foaming agents or by using mechanical means, e.g. adding preformed foam
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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
- C04B2111/28—Fire resistance, i.e. materials resistant to accidental fires or high temperatures
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/34—Non-shrinking or non-cracking materials
- C04B2111/343—Crack resistant materials
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/40—Porous or lightweight 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
- C04B2201/30—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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- 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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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract
The invention belongs to the technical field of constructional engineering application, and particularly relates to a preparation method of a fireproof anti-cracking ultrahigh-performance concrete beam. The concrete beam comprises a concrete beam body and a reinforcing steel bar net rack arranged on the concrete beam body, wherein the reinforcing steel bar net rack comprises reinforcing steel bar net rings arranged at intervals along the long edge direction of the concrete beam body, transverse reinforcing steel bars and longitudinal reinforcing steel bars arranged in the reinforcing steel bar net rings, and the concrete beam body comprises a mixed cement part and an ultrahigh-performance concrete part wrapped outside the mixed cement part.
Description
Technical Field
The invention belongs to the technical field of constructional engineering application, and particularly relates to a preparation method of a fireproof anti-cracking ultrahigh-performance concrete beam.
Background
The fire disaster is a very common and destructive disaster, the direct loss caused by the fire disaster is only lower than that of drought and waterlogging, and the frequency of the fire disaster is the highest among various disasters; when a fire disaster occurs, performance indexes such as strength, rigidity and durability of the building material are obviously deteriorated, so that the bearing capacity and the seismic performance of a concrete member (or structure) are obviously reduced.
Under the conflagration condition, because the thermal expansion coefficient of steel is higher than the thermal expansion coefficient of concrete under the high temperature, can produce the gap in the interface department of steel and concrete for steel and concrete can not effectual combined operation, steel and concrete bear pressure load respectively, and simultaneously, in the cooling process, the concrete is great through its inside and outside difference in temperature when the natural cooling of air, causes the destruction aggravation of its inner structure. Therefore, the structure of the concrete beam is damaged, the service life of the concrete beam is further influenced, and the Ultra High Performance Concrete (UHPC) replaces the proportion of cement by adding mineral admixtures such as silica fume, fly ash and slag in a large proportion, so that the hydration reaction activity in the matrix is obviously improved. Therefore, compared with common concrete, the mechanical strength and durability of the UHPC are obviously improved, and the breaking strength, tensile strength and seismic energy consumption performance of the UHPC can be obviously improved by doping short fibers. However, the properties of ultra-high performance concrete also contribute to its susceptibility to bursting in the event of fire. The burst will reduce the section of the ultra-high performance concrete member, the internal temperature field is irregularly distributed, and the stressed steel bar is exposed. And the high-strength prestressed reinforcing steel bar is easy to generate stress relaxation and high-temperature creep under fire, the mechanical property is obviously degraded, the bearing capacity of the component is reduced, and the requirement of the preset fire-resistant grade is difficult to meet. Therefore, it is a major research direction to improve the fire resistance of the ultra-high performance concrete beam as much as possible in order to achieve a longer service life.
Disclosure of Invention
Aiming at the technical problems of the ultra-high performance concrete beam, the invention provides the preparation method of the fireproof anti-cracking ultra-high performance concrete beam which is reasonable in design, simple in structure, convenient to process and capable of effectively reducing fire damage.
In order to achieve the above object, the present invention provides a method for manufacturing a fireproof anti-cracking ultrahigh-performance concrete beam, which includes a concrete beam body and a reinforcing steel bar net rack disposed on the concrete beam body, wherein the reinforcing steel bar net rack includes reinforcing steel bar net rings disposed at intervals along a long side direction of the concrete beam body, and transverse reinforcing steel bars and longitudinal reinforcing steel bars disposed in the reinforcing steel bar net rings, the concrete beam body includes a mixed cement portion and an ultrahigh-performance concrete portion wrapped outside the mixed cement portion, the mixed cement portion wraps the reinforcing steel bar net rings, the transverse reinforcing steel bars and the longitudinal reinforcing steel bars extend out of the mixed cement portion, the mixed cement portion is formed by foaming cement and ultrahigh-performance concrete, and the method for manufacturing the fireproof anti-cracking ultrahigh-performance concrete beam includes the following steps:
a. firstly, weighing the needed ultra-high molecular weight polyethylene fiber according to the corresponding proportion of the ultra-high performance concrete for surface modification, and improving the bonding capacity of the ultra-high molecular weight polyethylene fiber for later use;
b. then, weighing corresponding nano materials according to the corresponding proportion of the ultra-high performance concrete, dissolving the nano materials in a gelatin solution, and performing ultrasonic dispersion;
c. b, adding the ultra-high molecular weight polyethylene fiber prepared in the step a into a gelatin solution, performing ultrasonic dispersion uniformly, and performing freeze drying to obtain the ultra-high molecular weight polyethylene fiber attached with gelatin for later use;
d. then weighing the cement, the porous ceramic powder and the foam stabilizer required for preparing the foamed cement, and adding the cement, the porous ceramic powder and the foam stabilizer into a stirring kettle for dry mixing uniformly;
e. after the mixture is uniformly stirred, adding water into the stirring kettle, and continuously stirring;
f. quickly adding the foaming catalyst into hydrogen peroxide, quickly stirring, quickly adding into a stirring kettle, and continuously stirring at the stirring speed of 1000r/min;
g. after 1 minute, adding the carbon fiber-based SiO2 aerogel and the coagulant into the stirring kettle, and continuously stirring to obtain a spare tire;
h. then, mixing dry materials required by the ultra-high performance concrete together and uniformly stirring for later use;
i. then adding part of the uniformly mixed dry materials into stirring equipment, and adding the high-performance water reducing agent dry powder into the stirring equipment while continuously stirring to ensure that the dry materials and the high-performance water reducing agent dry powder are fully and uniformly mixed;
j. weighing the required water according to the water-to-glue ratio of 0.16;
k. then, uniformly stirring the mixture of the dry material and the high-performance water reducing agent dry powder obtained in the step i and all the water obtained in the step j, adding the ultrahigh molecular weight polyethylene fiber attached with the gelatin obtained in the step c, uniformly stirring, and then adding the foamed cement prepared in the step g;
after stirring, injecting the stirred slurry into a mold, and naturally curing for one day to obtain a mixed cement part;
m, after the maintenance is finished, adding the uniformly mixed dry materials left in the step i into stirring equipment, and adding the high-performance water reducing agent dry powder while continuously stirring to fully and uniformly mix the dry materials and the high-performance water reducing agent dry powder;
n, adding the mixture into stirring equipment according to the water-to-glue ratio of 0.18, adding the rest of the ultra-high molecular weight polyethylene fibers adhered with the gelatin in the rest step c, uniformly stirring, removing the mold of the mixed cement part, injecting the mixture into the mold of the ultra-high performance concrete part, curing and molding, and curing and molding to obtain the fireproof anti-cracking ultra-high performance concrete beam;
and in the n steps, the curing and forming method comprises the steps of placing the hardened and demoulded fireproof anti-cracking ultrahigh-performance concrete beam into a dry heat curing box, curing at the constant temperature of 50 ℃ for 1 day, heating to 230 ℃ at the heating rate of 30 ℃/h, then maintaining for one day, taking out the fireproof anti-cracking ultrahigh-performance concrete beam after curing is completed, and continuing standard curing to 28 days to obtain the fireproof anti-cracking ultrahigh-performance concrete beam.
Preferably, in the step k, the addition amount of the foamed cement is one tenth of the mass of the mixed cement portion.
Preferably, in the step h, the dry materials are cement, silica fume, mineral powder, quartz powder and quartz sand.
Preferably, in the step h, the mass ratio of cement, silica fume, mineral powder, quartz powder and quartz sand is 1: 0.13:0.1:1:0.22.
Preferably, the dry powder of the high-performance water reducing agent accounts for 2 percent of the mass of the dry material.
Compared with the prior art, the invention has the advantages and positive effects that,
1. the invention provides a preparation method of a fireproof anti-cracking ultrahigh-performance concrete beam, which is characterized in that the structure of the existing ultrahigh-performance concrete beam is improved, so that foamed cement is doped in the ultrahigh-performance concrete wrapping a reinforcing steel bar net rack, the closed pore characteristics of the foamed cement are utilized, the integral heat conduction system is reduced, and the internal temperature is further controlled, so that the influence of fire houses on the beam is reduced, and the purpose of prolonging the service life is achieved.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the description of the embodiments are briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without inventive labor.
Fig. 1 is a schematic structural view of a fireproof and cracking-resistant ultra-high performance concrete beam provided in example 1;
in the above figures, 1, a concrete beam body; 11. a mixed cement part; 12. an ultra-high performance concrete section; 2. a steel bar net rack; 21. a steel bar net ring; 22. transverse reinforcing steel bars; 23. longitudinal reinforcing steel bars.
Detailed Description
In order that the above objects, features and advantages of the present invention can be more clearly understood, the present invention will be further described with reference to the accompanying drawings and examples. It should be noted that the embodiments and features of the embodiments of the present application may be combined with each other without conflict.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, however, the present invention may be practiced in other ways than those specifically described herein, and therefore the present invention is not limited to the specific embodiments of the present disclosure.
The important improvement of this embodiment lies in that the concrete beam body 1 includes the mixed cement portion 11 and the ultra-high performance concrete portion 12 wrapped outside the mixed cement portion 11, wherein, the main purpose of the mixed cement portion 11 is to reduce the thermal conductivity coefficient while guaranteeing other various performances, and there are two purposes set in this way, one is difficult for the reinforcing bar to be heated, thus lead to the inflation, the second purpose is, in the cooling process, the inside and outside temperature difference is great when the concrete is naturally cooled by the air, and this great mainly refers to the reason that the outside temperature is lower than the inside temperature and produces, if the inside temperature rises not greatly, then under the condition that the influence of the rapid reduction of the outside temperature to the inside is less, this problem can be solved, for this reason, the mixed cement portion 11 wraps the reinforcing bar net ring 21 in, the setting of the horizontal reinforcing bar 22 and the longitudinal reinforcing bar 23 stretching out of the mixed cement portion 11, this setting, can make the reinforcing bar that is located in the mixed cement portion 11 can not be too high in temperature, thus, can reduce the inflation as far as possible. The purpose of wrapping the ultra-high performance concrete part 12 is mainly because in this embodiment, the mixed cement part 11 is formed by mixing foamed cement and ultra-high performance concrete, and the foamed cement will be pulverized to a certain extent after receiving high temperature, and the pulverization will cause other changes, which affect the service life, for this reason, the ultra-high performance concrete part 12 is used for protection, and the ultra-high performance concrete part 12 is made of ultra-high performance concrete, which is easy to crack, and therefore, in order to improve the crack resistance, this embodiment also improves the processing method thereof.
The preparation method of the fireproof anti-cracking ultrahigh-performance concrete beam comprises the following steps:
in this embodiment, the dry materials are cement, silica fume, mineral powder, quartz powder and quartz sand, wherein the cement is 42.5-grade ordinary portland cement.
The main component of the silica fume is silicon dioxide, also called as micro-silica powder, which is a by-product in the smelting of metal silicon and ferrosilicon alloy. The role of silica fume in concrete is mainly the volcano ash chemical effect and the micro aggregate filling physical effect. The silica can react with calcium hydroxide after cement hydration, and the combination product is calcium silicate gel. The calcium hydroxide has a reducing effect on the strength of the concrete, but the calcium silicate gel can increase the strength of the concrete, so the strength of the concrete can be improved to a certain extent by adding the silica fume. After the additive is added into UHPC, the function of improving the compactness of the UHPC can be achieved.
The fly ash is mainly waste fine ash collected from a chimney of a coal-fired power plant, can be recycled as an admixture in concrete, can play a filling effect and a ball bearing effect in a UHPC matrix, and improves the fluidity of the UHPC matrix.
Mineral powder, also known as granulated blast furnace slag powder, is one of the important materials for preparing high-performance concrete acknowledged in the world today. In the preparation of UHPC, during steam curing, the mineral powder can exert volcanic ash activity, can effectively reduce the content of calcium hydroxide in the matrix, and is beneficial to improving the strength of the UHPC. In addition, it can be used as micro aggregate in the matrix to improve the pore structure in the matrix, increase the density and play a role in filling.
Quartz sand is present as an aggregate in the preparation of UHPC.
The quartz powder mainly plays a filling role in UHPC, and the quartz powder fills gaps among other particles with a tiny particle size, so that the bulk density of the UHPC is improved.
The high-performance water reducing agent dry powder is a polycarboxylic acid high-efficiency water reducing agent which is a high-performance water reducing agent and is one of indispensable raw materials for preparing UHPC. The main function of doping a small amount of high-efficiency water reducing agent in UHPC is to ensure that the prepared UHPC still has good workability and mechanical property under the condition of extremely low water-to-gel ratio.
The fiber mainly fulfills the toughening purpose in UHPC, at present, steel fiber and ultra-high molecular weight polyethylene fiber are commonly used in the market, in the embodiment, short fiber of the ultra-high molecular weight polyethylene fiber is selected, and the mixing amount of the short fiber is 2 percent of the total volume.
The nano material is nano CaCO 3 Nano SiO 2 Nano Al 2 O 3 Sodium and sodiumRice MgO, carbon nanotubes, and graphene oxide, in this embodiment, graphene oxide is selected. The doping amount is 0.026% of the total weight.
The addition amount of the nano material is small in the whole preparation of the ultra-high performance concrete, and the water-gel ratio of the ultra-high performance concrete is low, so that the nano material is difficult to disperse.
Therefore, the purpose of nano material dispersion is achieved. In this embodiment, firstly, the required ultra-high molecular weight polyethylene fibers are weighed according to the corresponding proportion of the ultra-high performance concrete to perform surface modification, so as to improve the bonding capability of the ultra-high molecular weight polyethylene fibers, for standby use, the improvement of the bonding capability of the ultra-high molecular weight polyethylene fibers mainly takes into account that the ultra-high molecular weight polyethylene fibers are large in doping amount, generally have a diameter of about 3mm, and have a certain volume, so that when stirring is performed by using stirring equipment, the ultra-high molecular weight polyethylene fibers can be uniformly dispersed, and the nano material is adsorbed on the ultra-high molecular weight polyethylene fibers, so that the purpose of improving dispersibility can be achieved by using the nano material.
There are many methods for modifying the ultra-high molecular weight polyethylene fiber, and this embodiment provides a method with a good effect, which specifically includes the following steps:
soaking the ultra-high molecular weight polyethylene fiber in ethanol, ultrasonically cleaning and drying; carrying out plasma treatment on the washed and dried ultrahigh molecular weight polyethylene fibers; and finally, soaking the ultra-high molecular weight polyethylene fiber after the plasma treatment in an ethanol/water mixed solution containing a silane coupling agent, taking out after reacting for 1-5 h, and carrying out dehydration condensation reaction at 90-130 ℃ for 0.5-3 h to obtain the ultra-high molecular weight polyethylene fiber with improved bonding capacity. The purpose of doing so is to improve the surface roughness of the ultra-high molecular weight polyethylene fiber under the action of ensuring the performance of the ultra-high molecular weight polyethylene fiber, and further improve the bonding capability of the ultra-high molecular weight polyethylene fiber for later use.
Then, weighing corresponding nano materials according to the corresponding proportion of the ultra-high performance concrete, then dissolving the nano materials in gelatin solution, and performing ultrasonic dispersion, wherein in the embodiment, gelatin is selected mainly in consideration of the fact that gelatin is solid at low temperature and begins to liquefy under the condition of about 30-34 ℃, and along with the liquefaction of gelatin, the nano materials can be separated from the ultra-high molecular weight polyethylene fibers under the stirring action, and the nano materials are uniformly distributed under the action of the ultra-high molecular weight polyethylene fibers, so that the aim of uniform distribution is achieved after the nano materials are separated. The solid content of the gelatin solution is enough to meet the requirement of uniform attachment of the nano material, and a large amount of water can be added to immerse the gelatin when the gelatin solution is used.
Then, adding the ultra-high molecular weight polyethylene fiber into gelatin solution, after ultrasonic dispersion, freeze-drying, wherein the vacuum freeze-drying technology is a drying technology which freezes wet materials or solution into solid at a lower temperature (-10 ℃ to-50 ℃), then directly sublimes water in the solution into gas state without liquid state under vacuum (1.3-13 Pa), and finally dehydrates the materials, thus obtaining the ultra-high molecular weight polyethylene fiber attached with the gelatin for later use. This was done to ensure uniform dispersion by ultrasonic dispersion and then to ensure the gelatin containing nanomaterial to adhere to the ultra high molecular weight polyethylene fibers by vacuum freeze drying. Then, it is ready for use.
Then, 60 to 80 parts of cement is added; 10-20 parts of carbon fiber-based SiO2 aerogel; 10-20 parts of porous ceramic powder; 5-8 parts of hydrogen peroxide foaming agent; 0.3 to 0.5 portion of manganese oxide foaming catalyst; 5-8 parts of a coagulant of a compound of sodium carbonate and triethanolamine, wherein the mass ratio of the sodium carbonate to the triethanolamine is 10; 2-4 parts of a foam stabilizer of calcium stearate modified by a nano intercalation technology; the balance of water, and the cement is Portland cement. The porous ceramic powder is particles processed by the existing waste porous ceramics into particles with the particle size of 325 meshes, and the mesh size is the common particle size of the existing portland cement, and of course, the particle size can be larger and is not more than 180 meshes at most. The balance of water, the water-cement ratio of 0.46.
The cement, the porous ceramic powder and the foam stabilizer which are weighed are added into a stirring kettle to be uniformly dry-mixed, the purpose of the uniform dry-mixing is mainly to fully mix the cement, the porous ceramic powder and the foam stabilizer, calcium stearate modified by a nano-intercalation technology is selected as the foam stabilizer, and the stability of bubbles is a key factor related to the preparation process and the performance of the foamed cement in the process of growing the bubbles. Microscopically, in the porous material, a liquid film (namely, a liquid film generated by cement slurry) plays a role of separating bubbles, and the destruction of the bubbles is the rupture of the liquid film around the bubbles. The instability of the bubbles is also manifested by the bubbles fusing with each other and growing up. The stability of the bubbles is mainly affected by surface tension and cement paste viscosity. The change in surface tension causes a change in the size of the bubbles, and thus the surface tension affects the stability of the bubbles. In the early stage of mixing cement slurry, friction between internal fluid layers is quite complex, the formed slurry has low plastic viscosity and high flow rate, and bubbles are easy to fuse or break. For this purpose, in this embodiment, the cement, the porous ceramic powder and the foam stabilizer are added into a stirring kettle and mixed to be uniform.
The porous ceramic powder particles are mainly added into a flake structure rather than a particle structure, the smoothness of bubbles can be improved, the porous ceramic powder particles are mainly used for filling gaps because the porous ceramic powder particles do not react, and the flake porous ceramic powder particles provide an early strength effect for the foamed cement to form a good network-shaped frame structure.
After the mixture is uniformly stirred, water is added into the stirring kettle, the stirring is continued, the water-cement ratio is about 0.46, the existing research shows that the microbial foaming agent contains a large amount of water, and therefore, the integral ratio of the microbial foaming agent to the water reaches 0.46.
Then, the manganese oxide foaming catalyst is rapidly added into hydrogen peroxide, the mixture is rapidly stirred and then rapidly added into a stirring kettle, the stirring is continued, the stirring speed is 1000r/min, in the embodiment, the main function of adding the catalyst is to enable hydrogen peroxide to rapidly react, the same purpose is achieved by the same stirring rotating speed, and the hydrogen peroxide can complete the reaction within 10-20S, so that the purpose is that the foaming cement is preparedThe slurry can be condensed and hardened within 10 minutes, so that the reaction speed and the stirring speed are increased, bubbles are prevented from rising more sufficiently, the bottom of the mold is free of bubbles, the number of bubbles on the upper portion is large, uniform distribution of the bubbles is ensured, and meanwhile, convenience is brought to carbon fiber-based SiO 2 And (4) adding aerogel.
After 1 minute, the carbon fiber-based SiO was then applied 2 Aerogel and coagulant are added to the stirred tank and stirring is continued, in this example, carbon fiber based SiO 2 The addition of the aerogel can seal a large amount of microcracks, improve the closed porosity and avoid the reaction of the carbon fiber-based SiO 2 The aerogel can be used as a supplement to bond cement and porous ceramic powder particles together to form a good network-like framework structure.
The coagulant added at this time also has the effect of preventing the slurry from rapidly solidifying, and the carbon fiber-based SiO 2 The aerogel does not work, in the embodiment, the coagulant mixed by the mass ratio of sodium carbonate to triethanolamine of 10.
During the stirring process of the re-foaming cement, the ultra-high performance concrete also needs to be prepared, because the ultra-high performance concrete and the foaming cement need to be fully fused, and the closed cells and bubbles of the foaming cement are uniformly distributed by utilizing the uniform distribution of the foaming cement, thereby achieving the purpose of heat insulation.
Therefore, dry materials required by the ultra-high performance concrete are mixed together and stirred uniformly, and then the high-performance water reducing agent dry powder is added into the uniformly mixed dry materials and stirred, so that the dry materials and the high-performance water reducing agent dry powder are fully and uniformly mixed, and the step is a common preparation step of the ultra-high performance concrete, and is not described in detail.
Then, the required water is weighed according to the water-to-glue ratio of 0.16. (because the foamed cement contains a certain amount of water, the final water-cement ratio is 0.18, and therefore the water addition amount is small) then weighing a mixture of part of dry materials and high-performance water reducing agent dry powder, uniformly stirring the mixture with all the obtained water, then adding the ultra-high molecular weight polyethylene fibers attached with the gelatin into the mixture, and uniformly stirring the mixture. Meanwhile, the stirred foamed cement is added into the water, and in the process, as the hydration process is a heat release process, the gelatin can be heated in the hydration process, so that the gelatin is separated from the ultra-high molecular weight polyethylene fiber and can be distributed more uniformly along with stirring. At this time, the foamed cement is uniformly distributed in the ultra-high performance concrete, curing is carried out, the curing is natural curing, and the purpose of curing is mainly to enable the mixed cement part 11 to be basically molded.
After the curing is completed, the mold is taken down, the mold of the ultra-high performance concrete part 12 is installed, then the residual dry materials and the high performance water reducing agent dry powder are fully and uniformly mixed, and then the required water is weighed according to the water-to-glue ratio of 0.18. And adding the rest ultra-high molecular weight polyethylene fiber attached with gelatin into the mixture, uniformly stirring the mixture, and pouring the mixture into a mould to obtain a coarse product of the fireproof anti-cracking ultra-high performance concrete beam. The main purpose of casting only after the preliminary molding of the mixed cement portion 11 is to make the mixed cement portion 11 have better integrity with the ultra-high performance concrete.
And then curing and forming the hardened and demoulded fireproof anti-cracking ultrahigh-performance concrete beam after hardening and forming, wherein the curing and forming method comprises the steps of placing the hardened and demoulded fireproof anti-cracking ultrahigh-performance concrete beam into a dry heat curing box, curing at the constant temperature of 50 ℃ for 1 day, heating to 230 ℃ at the heating rate of 30 ℃/h, then maintaining for one day, taking out the fireproof anti-cracking ultrahigh-performance concrete beam after curing is finished, and continuing standard curing for 28 days to obtain the fireproof anti-cracking ultrahigh-performance concrete beam. The aim of the method is to achieve the aim of sectional maintenance, and through experiments, the crack resistance of the sectional maintenance is better than that of standard maintenance and ordinary maintenance.
Then, carrying out a Fire bursting test according to ISO 834 standard, presetting the Fire test time to be 150min, when the deflection deformation of the beam reaches L/20 (L is a net span length), or the deformation rate reaches the Fire resistance limit judgment standard of Fire resistance tests (BSEN 1363-1; if the test piece is about to be damaged in 150min, continuing heating until the damage standard is reached; otherwise, the test is stopped.
The experimental conclusion is that: the fireproof anti-cracking ultrahigh-performance concrete beam does not burst in a 150-min fire test, and the design requirement is met.
The above description is only a preferred embodiment of the present invention, and not intended to limit the present invention in other forms, and any person skilled in the art may apply the above modifications or changes to the equivalent embodiments with equivalent changes, without departing from the technical spirit of the present invention, and any simple modification, equivalent change and change made to the above embodiments according to the technical spirit of the present invention still belong to the protection scope of the technical spirit of the present invention.
Claims (5)
1. The utility model provides a preparation method of anti ultra high performance concrete beam that splits of fire prevention, includes the concrete beam body and sets up the steel bar net rack at the concrete beam body, the steel bar net rack includes the steel bar net circle that sets up along the long limit direction interval of concrete beam body and sets up horizontal reinforcing bar and the longitudinal reinforcement in the steel bar net circle, a serial communication port, the concrete beam body is including mixed cement portion and the ultra high performance concrete portion of parcel outside mixed cement portion, wherein, including mixed cement portion wraps up the steel bar net circle, horizontal reinforcing bar and longitudinal reinforcement stretch out mixed cement portion and set up, mixed cement portion mixes for foaming cement and ultra high performance concrete and forms, and the preparation method of fire prevention anticracking ultra high performance concrete beam includes following step:
a. firstly, weighing required ultrahigh molecular weight polyethylene fibers according to the corresponding proportion of the ultrahigh performance concrete for surface modification, and improving the bonding capacity of the ultrahigh molecular weight polyethylene fibers for later use;
b. then, weighing corresponding nano materials according to the corresponding proportion of the ultra-high performance concrete, dissolving the nano materials in a gelatin solution, and performing ultrasonic dispersion;
c. b, adding the ultra-high molecular weight polyethylene fiber prepared in the step a into a gelatin solution, performing ultrasonic dispersion uniformly, and performing freeze drying to obtain the ultra-high molecular weight polyethylene fiber attached with gelatin for later use;
d. then weighing cement, porous ceramic powder and a foam stabilizer which are needed for preparing the foamed cement, adding the cement, the porous ceramic powder and the foam stabilizer into a stirring kettle, and uniformly mixing;
e. after the mixture is stirred uniformly, adding water into the stirring kettle, and continuing stirring;
f. quickly adding the foaming catalyst into hydrogen peroxide, quickly stirring, quickly adding into a stirring kettle, and continuously stirring at the stirring speed of 1000r/min;
g. after 1 minute, adding the carbon fiber-based SiO2 aerogel and the coagulant into the stirring kettle, and continuing stirring to prepare a spare tire;
h. then, mixing dry materials required by the ultra-high performance concrete together and uniformly stirring for later use;
i. then adding part of the uniformly mixed dry materials into stirring equipment, and adding the high-performance water reducing agent dry powder while continuously stirring to ensure that the dry materials and the high-performance water reducing agent dry powder are fully and uniformly mixed;
j. weighing the required water according to the water-to-glue ratio of 0.16;
k. then, uniformly stirring the mixture of the dry material and the high-performance water reducing agent dry powder obtained in the step i and all the water obtained in the step j, adding the ultrahigh molecular weight polyethylene fiber attached with the gelatin obtained in the step c, uniformly stirring, and then adding the foamed cement prepared in the step g;
l, after stirring, injecting the stirred slurry into a mold, and naturally curing for one day to obtain a mixed cement part;
m, after the maintenance is finished, adding the uniformly mixed dry materials left in the step i into stirring equipment, and adding the high-performance water reducing agent dry powder into the stirring equipment while continuously stirring the mixture to ensure that the dry materials and the high-performance water reducing agent dry powder are fully and uniformly mixed;
n, adding the mixture into stirring equipment according to the water-to-glue ratio of 0.18, adding the rest ultrahigh molecular weight polyethylene fibers attached with the gelatin in the rest step c, uniformly stirring, removing the mold of the cement mixing part, injecting the mixture into the mold of the ultrahigh performance concrete part, curing and molding,
after curing and forming, obtaining the fireproof anti-cracking ultrahigh-performance concrete beam after curing and forming; and in the n steps, the curing and forming method comprises the steps of placing the hardened and demoulded fireproof anti-cracking ultrahigh-performance concrete beam into a dry heat curing box, curing at the constant temperature of 50 ℃ for 1 day, then heating to 230 ℃ at the heating rate of 30 ℃/h, then maintaining for one day, taking out the fireproof anti-cracking ultrahigh-performance concrete beam after curing is completed, and continuing standard curing to 28 days to obtain the fireproof anti-cracking ultrahigh-performance concrete beam.
2. The method for preparing a fireproof and cracking-resistant ultra-high performance concrete beam according to claim 1, wherein in the k step, the addition amount of the foaming cement is one tenth of the mass of the mixed cement part.
3. The method for preparing a fireproof anti-cracking ultra-high performance concrete beam as claimed in claim 2, wherein in the step h, the dry materials are cement, silica fume, mineral powder, quartz powder and quartz sand.
4. The preparation method of the fireproof anti-cracking ultrahigh-performance concrete beam according to claim 3, wherein in the step h, the mass ratio of cement, silica fume, mineral powder, quartz powder and quartz sand is 1: 0.13:0.1:1:0.22.
5. The method for preparing the fireproof anti-cracking ultrahigh-performance concrete beam as claimed in claim 4, wherein the dry powder of the high-performance water reducing agent accounts for 2% of the mass of the dry materials.
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| CN116330436A (en) * | 2023-03-28 | 2023-06-27 | 中国海洋大学 | Porous hydraulic cementing film and preparation method and application thereof |
| CN116789424A (en) * | 2023-07-19 | 2023-09-22 | 捷安特（昆山）有限公司 | Preparation method of carbon fiber cement composite material |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116330436A (en) * | 2023-03-28 | 2023-06-27 | 中国海洋大学 | Porous hydraulic cementing film and preparation method and application thereof |
| CN116789424A (en) * | 2023-07-19 | 2023-09-22 | 捷安特（昆山）有限公司 | Preparation method of carbon fiber cement composite material |
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