CN101244608A - Cast-in-situ beam maintaining method - Google Patents

Abstract

The invention relates to a maintenance method for cast-in-place beam, which is characterized in that a steam pipeline is respectively arranged at the bottom of the bottom plate, in the lower side of two flange plates and in the internal box; a maintaining tarpaulin is supported at a steel tube bracket erected on walkway railing in both sides of the mould; the maintaining time for static period is between six to eight hours, and the constant temperature can be controlled between 30 to 35 DEG C; generally, the constant temperature period is kept for twelve hours, and the temperature decreasing speed is no more than five DEG C per hour. The maintenance method of the invention has the advantages of capability to provide complete maintenance technology for cast-in-place beam in field environment, great durability for cast-in-place beam, early removal for the internal mould, short turnover for mould and bracket, accelerated construction speed, increased construction efficiency, ensured prefabricated quality for the beam and saved cost.

Description

Cast-in-situ beam maintaining method

Technical field

The present invention relates to a kind of cast-in-situ beam maintaining method.

Background technology

Existing heat and moisture preserving maintaining process is mostly at bridge girder plant or precast plant and decide, and maintenance problem and complete maintaining process extremely are short of in the cast-in-situ box girder lowered in field environment and be directed to.And the maintenance problem of cast-in-situ box girder also is of equal importance, the durability of cast-in-place beam, and the model turnaround time, the operation and the engineering cost of whole piece circuit made in same restriction.

Summary of the invention

The objective of the invention is: a kind of precast beam maintenance process is provided.

The objective of the invention is to realize by the enforcement following technical proposals:

A kind of cast-in-situ beam maintaining method is characterized in that: adopt following maintenance step:

Step 1, case beam are on pedestal before the maintenance of prefabricated back, in base plate bottom side and two flange plate downsides, interior case, respectively arrange one of jet chimney, each jet chimney adopts independently control valve, with military quilt or sponge back cover, set up steel pipe support on the railing of aisle, model both sides at the bed die downside, support ground keeps space, the 1m left and right sides in top of concrete, tarpaulin is supported on the support, hang down around it and form a maintenance cover, tight whole pedestal and case beam shade

Step 2, beam body concrete pouring finish, curing period to hydrothermal curing is limited to quiet stopping the phase, time was controlled at 6～8 hours, the quiet phase of stopping can be supplied with steam in a small amount temperature of shed is controlled at about 20 ℃ in canopy, the point for measuring temperature of temperature measurer is arranged in span centre, three cross sections of beam-ends head amount to 18 each observation station, represent in beam body web, base plate, top board, flange plate, the maintenance canopy respectively and interior oven temperature, degree.

Step 3: temperature is risen to the thermostat temperature of regulation by the quiet phase of stopping; Programming rate must not be greater than per hour 10 ℃, and programming rate is unsuitable too fast;

Step 4: thermostat temperature should be controlled at 30～35 ℃; Constant temperature phase ordinary circumstance keeps 12h, also can prolong constant temperature time by the laboratory decision according to the test specimen detection case;

Step 5: when reaching the regulation constant temperature time, take out with the concrete of beam maintenance and check that test specimen stops the steam supply cooling after test reaches concrete demoulding intensity, cooling rate is not more than per hour 5 ℃; When temperature of shed cool to canopy outside during temperature difference≤15 ℃, remove maintenance cover and temperature instrumentation;

In whole temperature controlled processes, regulate evaporation tube steam supply by control valve, the temperature of each one in the control maintenance cover, the temperature difference at each position is not more than 10 ℃ in the canopy cover.

Adopt above-described maintenance process, the curing temperature of moisture-heat preservation is controlled at 30-35 ℃, and to the late strength of concrete development, works durability effect is very obvious, and construction speed is fast, improves efficiency of construction, guarantees the beam prefabricated quality of case, has saved cost simultaneously.

Description of drawings

Fig. 1 is a cast-in-situ box girder curing means schematic diagram.

The point for measuring temperature layout drawing of Fig. 2 temperature measuring equipment.

The specific embodiment

The case beam is on pedestal before the maintenance of prefabricated back, respectively arrange 6 one of jet chimneys in base plate bottom side and two flange plate downsides, interior case, each jet chimney adopts independently control valve, at the bed die downside with military quilt or sponge 4 back covers, keep humidity in the maintenance canopy, prevent that steam from leaking.Set up steel pipe support 3 on aisle, the model both sides railing 1, support ground keeps space, the 1m left and right sides in top of concrete, is beneficial to steam and flows, and prevents the concrete hot-spot.Tarpaulin 2 is supported on the support, and hanging down around it forms a maintenance cover, tight whole pedestal and case beam shade, the concrete layout as shown in Figure 1.

Beam body concrete pouring finishes, curing period to hydrothermal curing is limited to quiet stopping the phase, time was controlled at 6～8 hours, the quiet phase of stopping can be supplied with steam in a small amount temperature of shed is controlled at about 20 ℃ in canopy, the point for measuring temperature 5 of temperature measurer is arranged in span centre, three cross sections of beam-ends head amount to 18 observation stations, represent in beam body web, base plate, top board, flange plate, the maintenance canopy respectively and interior oven temperature, degree.

Temperature is risen to the thermostat temperature of regulation by the quiet phase of stopping; Programming rate must not be greater than per hour 10 ℃, and programming rate is unsuitable too fast;

Thermostat temperature should be controlled at 30～35 ℃; Constant temperature phase ordinary circumstance keeps 12h, also can prolong constant temperature time by the laboratory decision according to the test specimen detection case;

Step 5: when reaching the regulation constant temperature time, take out with the concrete of beam maintenance and check that test specimen stops the steam supply cooling after test reaches concrete demoulding intensity, cooling rate is not more than per hour 5 ℃; When temperature of shed cool to canopy outside during temperature difference≤15 ℃, remove maintenance cover and temperature instrumentation;

In whole temperature controlled processes, regulate evaporation tube steam supply by control valve, the temperature of each one in the control maintenance cover, the temperature difference at each position is not more than 10 ℃ in the canopy cover.

Adopt above-described maintenance process, complete maintaining process in the cast-in-situ box girder lowered in field environment is provided, the curing temperature of moisture-heat preservation is controlled at 30-35 ℃, late strength of concrete is developed, works durability effect is very obvious, on the one hand, has avoided concrete to endure cold when intensity is very low, the good environment that a strength development is arranged has been guaranteed its inherent quality; On the other hand, reduced case beam temperature difference between inside and outside concrete, make the secondary stress that causes by internal-external temperature difference reduce, prevented that Temperature Cracks from appearring in concrete, and it is early strong to have improved concrete, make the internal mold dismounting time in advance, model, support are shortened turnover period, have accelerated construction speed greatly, improved efficiency of construction, guarantee the beam prefabricated quality of case, saved cost simultaneously.

Claims (1)

1, a kind of cast-in-situ beam maintaining method is characterized in that: adopt following maintenance step:

Step 1, case beam are on pedestal before the maintenance of prefabricated back, in base plate bottom side and two flange plate downsides, interior case, respectively arrange one of jet chimney, each jet chimney adopts independently control valve, at the bed die downside with military quilt or sponge back cover, set up steel pipe support on the railing of aisle, model both sides, support ground keeps space, the 1m left and right sides in top of concrete, and tarpaulin is supported on the support, hang down around it and form a maintenance cover, tight whole pedestal and case beam shade;

Step 2, beam body concrete pouring finish, curing period to hydrothermal curing is limited to quiet stopping the phase, time was controlled at 6～8 hours, the quiet phase of stopping can be supplied with steam in a small amount temperature of shed is controlled at about 20 ℃ in canopy, the point for measuring temperature of temperature measurer is arranged in span centre, three cross sections of beam-ends head amount to 18 each observation station, represent in beam body web, base plate, top board, flange plate, the maintenance canopy respectively and interior oven temperature, degree.

Step 3: temperature is risen to the thermostat temperature of regulation by the quiet phase of stopping; Programming rate must not be greater than per hour 10 ℃, and programming rate is unsuitable too fast;

Step 4: thermostat temperature should be controlled at 30～35 ℃; Constant temperature phase ordinary circumstance keeps 12h, also can prolong constant temperature time by the laboratory decision according to the test specimen detection case;

Step 5: when reaching the regulation constant temperature time, take out with the concrete of beam maintenance and check that test specimen stops the steam supply cooling after test reaches concrete demoulding intensity, cooling rate is not more than per hour 5 ℃; When temperature of shed cool to canopy outside during temperature difference≤15 ℃, remove maintenance cover and temperature instrumentation;

In whole temperature controlled processes, regulate evaporation tube steam supply by control valve, the temperature of each one in the control maintenance cover, the temperature difference at each position is not more than 10 ℃ in the canopy cover.

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