CN113370367B

CN113370367B - Combined UHPC (ultra high performance polycarbonate) curing method

Info

Publication number: CN113370367B
Application number: CN202110728449.XA
Authority: CN
Inventors: 刘志峰; 陈松涛; 吴夏宗; 冯翔
Original assignee: Poly Changda Engineering Co Ltd
Current assignee: Poly Changda Engineering Co Ltd
Priority date: 2021-06-29
Filing date: 2021-06-29
Publication date: 2022-05-13
Anticipated expiration: 2041-06-29
Also published as: CN113370367A

Abstract

The invention discloses a combined UHPC (ultra high performance polycarbonate) curing method, which comprises three curing procedures, namely primary curing with a mold, demolding, spraying curing and high-temperature steam curing, wherein a temperature control system aiming at the three curing procedures is arranged in the curing method, and the curing is carried out on the UHPC through the three curing procedures, so that the temperature difference between the inside and the outside of the structure is reduced, and the hydration effect of the UHPC is promoted; when the long-line method is used for prefabricating, the sections on the two sides of the platform are prefabricated to the middle, the operation point is changed continuously, and fixed maintenance facilities cannot be adopted; and the steam curing facilities are not easy to be arranged due to limited field at the beam-making pedestal, reasonable steam curing modes and facilities are needed, the UHPC section prefabricated box beam curing facilities are more, accurate control is required, manual operation cannot be performed, a set of efficient control system is adopted, the curing quality is improved, and the labor cost is reduced.

Description

Combined UHPC (ultra high performance polycarbonate) curing method

Technical Field

The invention relates to the field of ultra-high performance concrete (UHPC) curing, in particular to a combined UHPC curing method.

Background

The UHPC mainly comprises materials such as cement, silica fume, fly ash, a water reducing agent, quartz sand, steel fiber and the like; the material is constructed according to the principle of maximum compactness, and the pores among the material particles are filled with materials with smaller particle sizes, so that the pores and microcracks in the material can be minimized; it has ultra-high strength and excellent durability due to its high compactness. The steel fiber dispersed in the UHPC can greatly slow down the expansion of the microcracks in the material, so that the UHPC has ultrahigh toughness. The UHPC is not added with coarse aggregate, and the used cement has high strength grade, large dosage and large generated hydration heat and shrinkage; particularly, once the temperature difference between the surface and the interior of the concrete is overlarge, the box girder with a large volume and a complex structure generates great temperature stress; uneven concrete shrinkage of each part in a complex structure can generate tensile stress in the structure; under the action of the two main stresses, the large-size box girder with the complex structure is easy to crack, the structural strength and the durability of the bridge are affected, and the consequence is very serious.

Maintenance of the large-volume box girder with the complex structure is one of the key factors for ensuring the performance of the box girder. UHPC concrete has two purposes: firstly, conditions for fully hydrating cement are created, and hardening of concrete is accelerated; and secondly, the phenomena of shrinkage, cracks, damage and the like which exceed the normal range due to the influence of natural factors such as sunshine, wind, dryness, cold and the like after the concrete is formed are prevented. The temperature and time requirements are different for the properties of UHPC and different strength grades. At present, the UHPC component with small volume or conventional structure is mainly cured by water and high-temperature steam in China.

Considering that the mature maintenance process aiming at the large-volume complicated-structure segmental precast box girder does not meet the requirement of maintaining the UHPC component of the project at present, a novel combined UHPC maintenance mode and a control system aiming at the large-volume UHPC complicated-structure segmental precast box girder need to be invented. The UHPC component has the advantages of easy solidification, large compactness, fast strength improvement and good durability, and meets the construction conditions of the long-line method prefabricated segment box girder.

Disclosure of Invention

The invention aims to provide a combined UHPC curing method.

The technical problem solved by the invention is as follows:

(1) the UHPC section prefabricated box girder is large in volume, the temperature inside the structure is extremely high in the hardening process, and the average temperature is low (below 5 ℃ in extreme cases) in winter construction in some areas, so that the extremely large temperature difference between the inside and the outside of the prefabricated box girder is caused, and the temperature and the humidity are maintained through three maintenance procedures, so that the temperature difference between the inside and the outside of the structure of the prefabricated box girder is reduced, and the hydration effect of the prefabricated box girder is promoted;

(2) when the long-line method is used for prefabricating, the sections on the two sides of the platform are prefabricated to the middle, the operation point is changed continuously, and fixed maintenance facilities cannot be adopted; and steam curing facilities are not easy to be arranged in a limited place at the beam-making pedestal, and reasonable steam curing modes and facilities are required.

(3) The UHPC section precast box girder has more maintenance facilities, requires accurate control, cannot be operated by manpower, adopts a set of efficient control system, improves the maintenance quality and reduces the labor cost.

The purpose of the invention can be realized by the following technical scheme: a combined UHPC curing method comprises three curing procedures, namely primary curing with a mold, demolding, spraying and curing and high-temperature steam curing, wherein a temperature control system aiming at the three curing procedures is arranged in the curing method, and comprises the following steps;

the maintenance method comprises the following steps:

the method comprises the following steps: pouring concrete to manufacture the box girder, and standing for equal strength within a set time;

step two: in the standing equal-strength process, laying a preliminary maintenance facility with a mold, and arranging a temperature sensor;

step three: and (3) performing primary maintenance with a mold: the method comprises the following steps of judging the temperature difference between the inside and the outside of a beam body, supplying steam to the outside of the beam body when the conditions are met, and simultaneously radiating the inside of the beam body;

step four: demoulding, spraying and curing: dismantling the template, arranging a spraying maintenance facility outside the section to be maintained of the beam body, spraying and maintaining normal-temperature water, and keeping spraying and maintaining during the process of manufacturing the matched beam section of the beam body;

step five: and (4) transporting the manufactured matched beam section to a steam curing room, performing high-temperature steam curing, and then transporting the beam body to the next procedure.

The invention has the further technical improvements that: and in the first step, the box girder is poured on a girder manufacturing pedestal, a steam pipe interface and a water supply pipe interface are arranged on the girder manufacturing pedestal, air humidity data and air temperature data of the air environment are measured actually, and the air humidity data are matched with a set duration comparison table, so that the set duration with the same standing strength is determined.

The invention has further technical improvements that: at the area mould preliminary maintenance stage, temperature sensor real-time supervision roof beam internal and the external temperature data of roof beam to calculate its temperature difference, when temperature difference exceeded when setting for the difference in temperature, open the motorised valve, steam in the boiler room carries out the steam supply to the roof beam external portion through the steam pipe interface, simultaneously, starts the water pump motor, in the cooling tube of the internal portion of roof beam is inputed to normal atmospheric temperature water through the water supply pipe interface, absorbs the heat of the internal portion of roof beam and removes.

The invention has further technical improvements that: in the demolding spraying maintenance stage, before a template is removed, strength test is carried out on a concrete test block of a beam body to obtain demolding strength data, when the demolding strength data exceeds a demolding strength limit value, the template is removed, then a section to be maintained is calibrated, a spraying frame is covered on the outer side of the section to be maintained, a water supply pipe interface on a beam manufacturing pedestal is communicated with the spraying frame, canvas is arranged on the outer side of the spraying frame, the spraying frame and the section to be maintained of the beam body are coated together through the canvas, and a water pump motor is started to spray normal-temperature water to the outer surface of the beam body at regular time.

The invention has further technical improvements that: the matched beam section is manufactured while demoulding, spraying and maintaining, and spraying and maintaining are carried out on the matched beam section all the time in the manufacturing process of the matched beam section.

The invention has further technical improvements that: in the process of manufacturing the matched beam section of the section to be maintained, the starting or closing control operation of the water pump motor is automatically controlled according to the comparison result of the temperature and the humidity of the beam body and the preset value, and when the current matched beam section is manufactured, the spraying frame is moved to the next section to be maintained to perform repeated operation.

The invention has further technical improvements that: steam conduit, spray piping, air exhauster and temperature sensor have been laid to the room of curing by vaporization, through the temperature sensor temperature in the room of curing by vaporization real-time supervision, when needs keep rising temperature or constant temperature state, let in steam in to the room of curing by vaporization pipeline, when needs keep the cooling state, let in normal atmospheric temperature water in to spray piping, open the air exhauster simultaneously.

The invention has further technical improvements that: the internal and external temperature and the temperature rise and fall speed of the beam body in the preliminary curing process of the belt mold are controlled within the preliminary curing set threshold value, and the temperature rise and fall speed of the steam curing room are controlled within the final curing set threshold value in the high-temperature steam curing process.

Compared with the prior art, the invention has the beneficial effects that:

1. when the invention is used, in the preliminary curing stage with the mold, the temperature sensor monitors the temperature data inside and outside the beam body in real time, calculates the temperature difference, opens the electric valve when the temperature difference exceeds the set temperature difference, supplies steam to the outside of the beam body through the steam pipe interface in the boiler room, simultaneously starts the water pump motor, inputs normal temperature water into the cooling pipe inside the beam body through the water supply pipe interface, absorbs and removes the heat inside the beam body, in the demolding spray curing stage, before the template is disassembled, performs the strength test on the concrete test block of the beam body to obtain the demolding strength data, when the demolding strength data exceeds the demolding strength limit value, the template is disassembled, then the curing section is calibrated, the spray frame is covered outside the curing section, and the water supply pipe interface on the beam manufacturing pedestal is communicated with the spray frame, and the canvas is arranged outside the spray frame, the spray frame and the section to be cured of the beam body are coated together through the canvas, the water pump motor is started to spray normal-temperature water to the outer surface of the beam body at regular time, the UHPC section prefabricated box beam is large in size, the temperature inside the structure is extremely high in the hardening process, the average temperature in winter construction in some areas is low, the great temperature difference between the inside and the outside of the prefabricated box beam is caused, the temperature and humidity curing is carried out on the prefabricated box beam through three curing procedures, the temperature difference between the inside and the outside of the structure is reduced, and the hydration effect of the prefabricated box beam is promoted.

2. After the preliminary curing with the mold is carried out until the concrete reaches the mold removal strength, the template is removed, then spraying curing facilities are laid, the spraying frame is moved to the position of the section to be cured to cover the whole section to be cured, and the spraying frame is placed in the box chamber; the water supply pipe interface on the beam making pedestal is communicated with a spraying frame, a temperature control system controls a water pump motor to regularly supply normal-temperature water to spray on the outer surface of the beam body according to the temperature, the spraying frame is covered by canvas, the wettability of the outer surface of the beam body can be effectively kept, the moisture loss caused by air evaporation is reduced, the beam body keeps spraying and maintaining in the process of manufacturing a matched beam section, the beam body is prefabricated from sections at two sides of the pedestal to the middle part during the prefabrication by a long-line method, the operation point continuously changes, and fixed maintenance facilities cannot be adopted; and the steam curing facility is difficult to set up in the limited place of system roof beam pedestal department, need take reasonable steam curing mode and facility, spray the frame through setting up in a flexible way to moving to spraying the frame, carrying out the segmentation health preserving to the roof beam body, the reasonable place that has utilized has avoided the inconvenience that the dismouting brought repeatedly simultaneously.

3. Through setting up temperature sensor, gather the temperature data of the internal and external portion of roof beam in real time to turn into wireless signal through the temperature signal converter of fixing on the side form and launch to the main control system on, and then realize the automatic control to steam curing facility and spraying facility, can not only rely on the manual work to operate, take one set of efficient control system, improve the maintenance quality, reduce the human cost.

Drawings

In order to facilitate understanding for those skilled in the art, the present invention will be further described with reference to the accompanying drawings.

FIG. 1 is a schematic view of the process of the present invention;

FIG. 2 is a schematic view of the piping arrangement of the beam forming pedestal of the present invention;

FIG. 3 is a schematic view of the connection relationship of the side mold units according to the present invention;

FIG. 4 is a schematic cross-sectional view of the steam pipeline and the insulating layer according to the present invention;

FIG. 5 is a schematic view showing the demolded spray curing state according to the present invention.

In the figure: 1. a pedestal foundation; 2. pedestal buttresses; 3. bottom die; 4. a water supply hose; 5. a steam supply hose; 6. a movable joint; 8. side mould; 9. a steam line; 10. a vibrator; 11. an exhaust fan; 12. supporting a side mould; 13. a heat-insulating layer; 14. a spray rack; 15. a spray pipe; 16. rotating the spray head; 17. canvas.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1-5, a combined UHPC curing process, the curing process comprising the steps of:

the method comprises the following steps: after concrete is poured on a beam-making pedestal, standing for equal strength, wherein the set time of standing for equal strength is related to the current air humidity data and the current air temperature data, the air humidity data and the air temperature data in the current air environment are measured, and data comparison is carried out according to a provided set time comparison table to obtain set time suitable for standing for equal strength in the current air environment, wherein the set time comparison table is a data comparison standard obtained through multiple experimental arrangement in a laboratory environment;

step two: in the equal-strength process of the box girder, a preliminary maintenance facility with a mold is arranged, and the method specifically comprises the following steps: connecting steam pipe interfaces on the beam-making pedestal to steam pipe joints on the side mold 8, the box girder box chamber and the top cover; connecting the water supply pipe interface on the beam making pedestal to the spray pipe on the processing top cover and the cooling pipe in the beam body; temperature sensors in the side die 8, the processing top cover, the box chamber and the beam body are connected to a temperature signal converter fixed on the side die 8, and temperature signals are converted into wireless signals through the signal converter and are transmitted to a control host.

After the primary curing of the belt mold is started, the control host automatically acquires temperature data inside and outside the beam body through the temperature sensor, difference value operation is carried out on the temperature data inside the beam body and the temperature data outside the beam body to obtain a temperature difference value, if the temperature difference value is larger than a set temperature difference value, the set temperature difference value is specifically set to be 20 ℃, the temperature control system controls an electric valve in a boiler room to be opened and supplies steam, and the temperature outside the beam body is increased; and meanwhile, controlling a water pump motor to supply normal-temperature water at regular time, leading the normal-temperature water to carry away heat inside the beam body through a cooling pipe in the beam body, comparing the real-time temperature inside and outside the beam body with a primary curing set threshold value in the process of controlling the temperature inside and outside the beam body, calculating the change speed of the temperature inside and outside the beam body, and controlling the real-time temperature and the change speed of the temperature within the primary curing set threshold value by controlling the size of a switch of an electric valve and the power of the water pump motor.

Step three: the area mould is preliminary maintained to the concrete and is reached the back of form removal intensity, demolishs the template, lays immediately and sprays the maintenance facility, specifically does: the spraying frame 14 is transported to the position of the section to be cured to cover the whole section to be cured, and the spraying frame 14 is placed in the box chamber; the water supply pipe interface on the beam making pedestal is communicated to the spraying frame 14, the temperature control system regularly supplies normal-temperature water to spray to the outer surface of the beam body according to the temperature control water pump motor, the spraying frame 14 is covered by canvas 17, the humidity of the outer surface of the beam body can be effectively kept, the moisture loss caused by air evaporation is reduced, and the beam body keeps spraying and maintaining in the process of manufacturing the matching beam section.

Step four: after the beam body is matched with the section, the spraying frame 14 is moved to the next section to be cured, and the section is moved to a steam curing room, wherein a steam pipeline 9, a spraying pipeline 15, an exhaust fan 11 and a temperature sensor are arranged in the steam curing room. After the high-temperature steam curing is started, the control host automatically records the temperature in the steam curing room, and when the temperature needs to be raised or kept constant, the electric valve on the steam pipeline 9 is controlled to be opened to introduce steam into the steam curing room; when the temperature needs to be reduced, the spraying pipeline 15 and the exhaust fan 11 are opened, the real-time temperature inside and outside the beam body is compared with the final-maintenance set threshold value, the change speed of the temperature inside and outside the beam body is calculated, and the real-time temperature and the change speed of the temperature are controlled within the final-maintenance set threshold value by controlling the switch size of the electric valve and the gear of the exhaust fan 11.

Step five: after the high-temperature steam curing is finished, the secondary hydration reaction and shrinkage of the UHPC are basically finished, and the performance indexes such as strength and the like meet the design requirements, namely, the beam body is moved to a trimming pedestal to enter the next procedure.

The beam-making pedestal comprises a pedestal foundation 1 and pedestal buttresses 2, the pedestal foundation 1 is provided with three pedestal buttresses 2 at equal intervals, the top ends of the three pedestal buttresses 2 are jointly provided with a bottom die 3, a steam supply hose 5 and a water supply hose 4 are embedded in the bottom die 3, the steam supply hose 5 and the water supply hose 4 are horizontally arranged, two ends of the steam supply hose 5 and the water supply hose 4 are respectively provided with a movable joint 6, the movable joints are longitudinally arranged relative to the bottom die 3, the steam supply hose 5 is connected with a boiler room through an air supply pipe, and the water supply hose 4 is connected with a water pump motor through a water supply pipe;

the preliminary maintenance with the mold needs to arrange steam supply pipelines, side molds 8 and a processing top cover, wherein the arrangement of the steam supply pipelines is specifically to arrange a boiler room to a steam curing room and to arrange the boiler room to a beam-making pedestal (the steam supply pipelines are provided with interfaces along the longitudinal direction of the beam-making pedestal, so that steam is supplied to an operation point when the operation point moves along the pedestal during beam making; a steam pipeline 9, a heat preservation layer 13, an exhaust fan 11 and the like are erected on the side mold 8 and used for heating and cooling the side mold 8; the top cover is processed into a covering shed with the size of the area of a single maximum segment top plate by using a steel structure, the covering shed adopts a heat-insulating layer 13 as a surface layer, and a steam pipeline 9, a spray header and the like are arranged in the covering shed and used for ascending and cooling the top plate; the heat preservation layer 13 is specifically a heat preservation blanket, the heat preservation blanket is used under the bottom die 3 and used with the closed space at two ends of the inner cavity of the box chamber, the side die 8 is further provided with a plurality of vibrators 10, bubbles generated in the concrete pouring process are eliminated, the density is improved, the steam pipeline 9 is arranged on one side of the heat preservation layer 13, the side die 8 and the bottom die 3 are uniformly provided with a plurality of side die supports 12, and the side die 8 and the bottom die 3 are fixedly connected through the side die supports 12.

Demoulding steam curing needs to set up spray frame 14, and spray frame 14 adopts steel skeleton to process into the frame (cover the whole festival section that needs the maintenance), and the shower is laid to steel skeleton side and top surface department, and steel skeleton outside covers canvas 17, and sets up spray pipe 15 on spray frame 14, evenly sets up a plurality of rotatory nozzles 16 on spray pipe 15, reaches the purpose that evenly sprays, avoids temperature and humidity distribution difference to cause structural deformation greatly.

Wherein, the high-temperature steam curing needs to be separately provided with a special steam curing room.

The control system mainly comprises a control host, temperature sensors of all parts, a signal converter, a control circuit and electric valves of all parts, automatic and accurate control of maintenance facilities is achieved, labor intensity of workers is reduced, and quality of the beam body is guaranteed.

While one embodiment of the present invention has been described in detail, the description is only a preferred embodiment of the present invention and should not be taken as limiting the scope of the invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.

Claims

1. A combined UHPC curing method is characterized in that: the maintenance method comprises three maintenance procedures, namely primary maintenance with a mold, demolding, spraying maintenance and high-temperature steam maintenance, and a temperature control system for the three maintenance procedures is arranged in the maintenance method and comprises the following steps;

the maintenance method comprises the following steps:

the method comprises the following steps: pouring concrete to manufacture the box girder, and standing within a set time with equal strength, specifically: pouring of the box girder is completed on a girder making pedestal, a steam pipe interface and a water supply pipe interface are arranged on the girder making pedestal, air humidity data and air temperature data of an air environment are measured actually, and the air humidity data are matched with a set duration comparison table, so that the set duration with standing equal strength is determined;

step three: and (3) performing primary maintenance with a mold: through the internal and external difference in temperature of roof beam judgement, carry out the steam supply to the external portion of roof beam when satisfying the condition, dispel the heat to the internal portion of roof beam simultaneously, specifically:

in the preliminary maintenance stage with the mold, a temperature sensor monitors temperature data inside and outside the beam body in real time, the temperature difference of the temperature data is calculated, when the temperature difference exceeds a set temperature difference, an electric valve is opened, steam in a boiler room supplies steam to the outside of the beam body through a steam pipe interface, meanwhile, a water pump motor is started, normal-temperature water is input into a cooling pipe inside the beam body through a water supply pipe interface, and heat inside the beam body is absorbed and removed;

step four: demoulding, spraying and curing: dismantling a template, arranging a spraying maintenance facility outside a section to be maintained of the beam body, spraying and maintaining normal-temperature water, and keeping spraying and maintaining in the process of manufacturing a matched beam section of the beam body, in the stage, before dismantling the template, carrying out strength test on a concrete test block of the beam body to obtain demolded strength data, dismantling the template when the demolded strength data exceeds a demolded strength limit value, then calibrating the section to be maintained, covering a spraying frame (14) outside the section to be maintained, communicating a water supply pipe interface on a beam making pedestal with the spraying frame (14), arranging canvas (17) outside the spraying frame (14), coating the spraying frame (14) and the section to be maintained of the beam body together through the canvas (17), and starting a water pump motor to regularly spray the normal-temperature water to the outer surface of the beam body;

step five: and (4) transferring the manufactured matched beam section to a steam curing room, performing high-temperature steam curing, and transferring the beam body to the next procedure after the high-temperature steam curing is completed.

2. The combined UHPC curing method of claim 1, wherein the matched beam section is manufactured while demoulding and spray curing is performed, and the matched beam section is always spray cured in the manufacturing process.

3. The combined UHPC curing method of claim 1, wherein in the process of manufacturing the matched beam section of the section to be cured, the start or stop control operation of the water pump motor is automatically controlled according to the comparison result of the temperature and the humidity of the beam body and a preset value, and when the manufacturing of the current matched beam section is completed, the spray rack (14) is moved to the next section to be cured for repeated operation.

4. A combined UHPC curing method according to claim 3 wherein the steam curing room is provided with a steam pipe (9), a spray pipe (15), an exhaust fan (11) and a temperature sensor, the temperature in the room is monitored in real time by the temperature sensor, when it is desired to maintain a temperature-rising or constant-temperature state, steam is fed into the room through the steam pipe (9), when it is desired to maintain a temperature-lowering state, normal-temperature water is fed into the spray pipe (15) while the exhaust fan (11) is turned on.

5. The combined UHPC curing method of claim 4, wherein the internal and external temperature and the temperature increase and decrease speed of the beam body during the primary curing process with the die are controlled within the initial curing set threshold value, and the temperature increase and decrease speed of the steam curing room during the high-temperature steam curing process are controlled within the final curing set threshold value.