CN102635244A - Construction method of slide mould under high-temperature environment - Google Patents

Abstract

The invention provides a construction method of a slide mould under a high-temperature environment and belongs to the technical field of civil engineering construction. The method mainly comprises the following steps of: firstly, selecting a proper additive; dividing temperatures of each day into sections from time according to the characteristic that a day and night temperature difference is great; then, setting a concrete mixing proportion by sections; adding ice blocks when concrete is agitated; agitating by a concrete tank car and the like so as to reduce a temperature of casting concrete; when a mould slides, adopting an interval lifting process; and covering a cotton felt on the surface of the cast concrete and utilizing an annular spraying and maintenance measure. By using the method, the technical difficulty that the slide mould cannot be realized by a regular construction method under the environment with a high temperature and the great day and night temperature difference is solved; and the method disclosed by the invention has the characteristics of fast construction period and low cost.

Description

The job practices of sliding formwork under hot environment

Technical field

The invention belongs to the civil engineering technical field, be specifically related to the job practices of a kind of sliding formwork under hot environment.

Background technology

In the also Monba gill cement mill project that certain unit undertakes the construction of, need build 1 of raw material homogenizing storehouse, 3 of clinker warehouses, 4 of cement bunkers, storehouse top mark Gao Jun is about 45m; Interior diameter is all about 20m; Wall thickness is 350mm, and strength grade of concrete C30 requires to adopt slding form operation.This engineering is positioned at desert area, and 39 ℃ of the annual mean highest temperatures are during construction; 48 ℃ of day maximum temperatures; Maximum 20 ℃ of day and night temperature, and the locality is Portland cement, the early strength height; Following at present problem is produced in conventional slding form operation meeting: concrete slump loss is fast, and is almost nil 1.5 hours inner concrete slumps; Concrete initial set, final setting time weak point, wherein the initial setting time is 1.5h, final setting time 2.5h; Normally night, the ready-mixed concrete mold clearing temperature reached 36-37 ℃.Thereby can't satisfy concrete from agitator to the pouring place haulage time 0.5h and from pump truck or ground pump to the sliding formwork storehouse wall build the requirement of the thick needs 1h of 500mm.

48 ℃ of maximum temperatures, it is high and can't carry out the problem of reinforced concrete structure sliding formwork that under the environment that day and night temperature is maximum 20 ℃, because of concrete slump loss is big, initial set, final setting time are short, concrete stirs mold clearing temperature.Under the big environment of high temperature, day and night temperature, the reinforced concrete structure sliding formwork can't be realized by conventional slding form operation method.

Summary of the invention

The present invention is directed to the technical problem that existing slding form operation method exists under the hot environment, the job practices of a kind of sliding formwork under hot environment is provided.

The job practices particular content of sliding formwork provided by the present invention under hot environment is following:

(1) selects suitable Concrete admixtures; This Concrete admixtures requires to satisfy the requirement of concrete design strength and the slding form operation requirement under the hot environment; Be that concrete strength meets design requirement; Concrete slump >=the 160mm of pouring location, initial setting time >=2.5h, final setting time >=4h;

(2) characteristics big according to day and night temperature, segmentation is provided with concrete mix;

(3) stir through on the rocks, the concrete tank of ready-mixed concrete, reduce the mold clearing temperature and the molding temperature of ready-mixed concrete, promptly the concrete molding temperature be controlled at≤33 ℃, reduce the obstruction and the slump-loss of concrete pump;

(4) take intermittently that sliding formwork promotes technology, concrete correlated performance is complementary under this at intermittence sliding formwork lifting technology and the hot environment;

(5) on the surface of concreting, cover cotton felt and adopt annular spray maintenance measure, reduce concrete and produce the crack because of dehydration.

The inventive method is specified as follows at present:

1, selects the suitable external agent for use

In order to solve concrete initial set, the short technical problem of final setting time, when design of concrete, at first select the suitable external agent for use.

According to the performance of different Admixtures, the Admixture of selecting for use should possess following characteristics:

(1) is liquid, is convenient to metering.

(2) under the prerequisite of guaranteed strength, has deferred action, i.e. concrete initial set time >=2.5h, final setting time >=4h.

(3) have the buck effect, the slump >=160mm reduces pump pressure simultaneously.

(4) reduce cement consumption, reduce the heat of hydration that cement produces.

Concrete is joined by degree of the falling .1o examination of routine, and Admixture is pressed cement consumption admixture step by step, until satisfying above requirement.

2, segmentation is provided with concrete mix

According to the big characteristics of day and night temperature every day, in time with the temperature section of every day, according to temperature section with also segmentation setting of concrete mix, to adapt to the temperature requirement of different time sections.

Press the concrete mix that temperature section is provided with, only need adjustment Admixture consumption, concrete is consistent at the correlated performance of different time sections basically.

3, reduce the going out of ready-mixed concrete, molding temperature

It is on the rocks when (1) concrete stirs

According to curing temperature relation in the U.S. " the high temperature concrete ACI 305R-1999 " standard, the mold clearing temperature that adopts ready-mixed concrete on the rocks is calculated in temperature, the slump and water requirement, makes it satisfy the mold clearing temperature requirement after concrete stirs.

(2) to template sunshade, watering cooling, reduce concrete molding temperature.

(3) adopt the concrete tank stirring technique

Enforcement through above measure; Reduced the concrete molding temperature, both the concrete molding temperature be controlled at≤33 ℃, reduce concrete stir, slump-loss in the transportation; Concrete slump>=the 160mm of pouring location satisfies the pumping condition and has reduced the plugging phenomenon.

4, sliding formwork adopts and intermittently promotes technology

The time of each climbing shuttering was controlled at about one hour under the normal temperature; When the concreting lap time is long under the high temperature,, whenever promoted 2-3 stroke at a distance from 30 minutes for reducing concrete lift height; Each stroke 50～100mm promotes about 250mm at every turn.

5, on the surface of concreting, cover cotton felt and adopt annular spray maintenance measure

Conventional concrete curing be direct water pipe at interval certain hour the concrete surface behind the final set 4h is watered, the dehydration under hot environment of this method is fast, can not satisfy concrete maintenance demand.

Maintenance process after the improvement adopts high-pressure hydraulic pump and circular spray tube on the cotton felt that covers on the wall of inside and outside storehouse, to spray water on the basis that cotton felt covers on the concrete surface of having built, and daytime is every at a distance from 1-2 hour water spray once, keeps the storehouse wall moist; Confirm according to temperature night.

The beneficial effect of the inventive method is following:

Use of the present invention has solved also Monba gill cement plant 48 ℃ of maximum temperatures, under the environment that day and night temperature is maximum 20 ℃; Because of concrete slump loss big; Initial set, final setting time are short, and molding temperature is high and can't carry out the problem of reinforced concrete structure sliding formwork, make characteristics fast, that cost is low of conventional slding form operation duration be able to continue use down at high temperature, environment that day and night temperature is big; Shorten the duration, reduced cost.

The specific embodiment

The inventive method practical implementation step is following:

1, selects the suitable external agent for use

Select Rheobuild 850 Admixtures that are suitable for the high temperature characteristics for use, these Admixture original producton location United Arab Emirates, fluid concrete under hot climate; Performance with raising and curing concrete reduces pump pressure, prolongs concrete apart from advantages such as transportations; Its initial setting time: 3h; Final setting time: 4.5h, the slump: 180～220mm, intensity satisfies the C30 requirement.

Concrete is joined by degree of the falling .1o examination of routine, and Admixture is pressed cement consumption admixture step by step, until satisfying above requirement.

2, segmentation is provided with concrete mix

The characteristics big according to local day and night temperature in time with temperature section, are the high temperature period between at 10 in the morning at 3 in afternoon, after at 3 in afternoon to 10 of the next mornings be the general period, design two kinds of match ratios, press the period and adjust the Admixture consumption.

Press the concrete mix that temperature section is provided with, only need adjustment Admixture consumption, concrete is consistent at the correlated performance of different time sections basically.

3, reduce the going out of ready-mixed concrete, molding temperature

It is on the rocks when (1) concrete stirs

According to curing temperature relation in the U.S. " the high temperature concrete ACI 305R-1999 " standard, the mold clearing temperature that adopts ready-mixed concrete on the rocks is calculated in temperature, the slump and water requirement, makes it satisfy the mold clearing temperature requirement after concrete stirs.

(2) to template sunshade, watering cooling, reduce concrete molding temperature.

(3) adopt the concrete tank stirring technique

Concrete tank is made up of two motors, and one is used for vehicle ', and one is used for the concrete stirring, simultaneously, is provided with the control water meter in the concrete tank.

Concrete mixing plant only carries out concrete batching, adds 70% frozen water during batching, in tank car, stirs and adds 30% water, reduces concrete transportation, mixing time, reduces slump-loss.

Enforcement through above measure; Reduced the concrete molding temperature, both the concrete molding temperature be controlled at≤33 ℃, reduce concrete stir, slump-loss in the transportation; Concrete slump>=the 160mm of pouring location satisfies the pumping condition and has reduced the plugging phenomenon.

4, sliding formwork adopts and intermittently promotes technology

Whenever promoted 2-3 stroke at a distance from 30 minutes, each stroke 50～100mm promotes about 250mm at every turn.Hoistway is separated by the decision of depanning concrete surface intensity, and the lifting operating personnel must in time observe concrete surface, and links up with the related personnel, accomplishes that the lifting of water velocity and platform is complementary.

5, on the surface of concreting, cover cotton felt and adopt annular spray maintenance measure

On the basis that cotton felt covers on the concrete surface of having built, adopt high-pressure hydraulic pump and circular spray tube on the cotton felt that covers on the wall of inside and outside storehouse, to spray water, daytime is every at a distance from 1-2 hour water spray once, keeps the storehouse wall moist; Confirm according to temperature night.

Claims (1)

1. the job practices of a sliding formwork under hot environment is characterized in that this method particular content is following:

(1) selects suitable Concrete admixtures; This Concrete admixtures requires to satisfy the requirement of concrete design strength and the slding form operation requirement under the hot environment; Be that concrete strength meets design requirement; Concrete slump >=the 160mm of pouring location, initial setting time >=2.5h, final setting time >=4h;

(2) characteristics big according to day and night temperature, segmentation is provided with concrete mix;

(3) stir through on the rocks, the concrete tank of ready-mixed concrete, reduce the mold clearing temperature and the molding temperature of ready-mixed concrete, promptly the concrete molding temperature be controlled at≤33 ℃, reduce the obstruction and the slump-loss of concrete pump;

(4) take intermittently that sliding formwork promotes technology, concrete correlated performance is complementary under this at intermittence sliding formwork lifting technology and the hot environment;

(5) on the surface of concreting, cover cotton felt and adopt annular spray maintenance measure, reduce concrete and produce the crack because of dehydration.