Sleepers shall be laid on the treated foundation, and supports shall be erected on the sleepers.
The bottom surface of the lower part of the steel hoop is processed and leveled as a whole, and the steel hoop is supported by channel steel.
⑤ concrete The soil mixture shall be mixed evenly, the color shall be consistent, and there shall be no segregation and bleeding.
I-beams shall be placed horizontally on the support and firmly connected with each other.
The purpose of preparation is to clarify the construction process, operation points and quality standards of highway bridge capping, and standardize and guide the construction of bridge capping.
The split screw shall be used to make the formwork in place.
③ The reinforcement must be straightened and derusted before processing.
the surface of reinforcement shall be clean, and the surface oil stain, paint dirt, scale rust, etc.
② The quantity of reinforcement shall be determined according to the diameter, shape and blanking size of reinforcement according to the design drawings.
5.2 formwork installation (1) shaped combined formwork shall be adopted for bent cap bottom formwork and side formwork, which shall be processed by professional formwork manufacturers.
full support shall be erected on the ground below the bent cap, and then formwork shall be laid on the support; ② Hoop and cantilever type, that is, set steel plate hoops on the pier column under the bent cap, tighten the splicing bolts of the hoops, and then use the hoops to set up the support and lay the formwork.
③ the concrete raw materials shall be accurately prepared in strict accordance with the construction mix proportion.
(2) When the floor support ① is in the form of full support, the base within the construction range under the bent cap shall be treated.
③ concrete cushion blocks of the same grade shall be set between the reinforcement and the formwork.
5.3 reinforcement installation (1) reinforcement blanking and processing ① reinforcement shall have factory certificate or test report when entering the site, and shall be accepted in batches, stored separately and set up signboards according to different specifications, grades, steel grades and grades.
During lifting, the four point lifting method is used, and the positioning of the reinforcement framework must meet the requirements Meet the requirements of the design and bridge and culvert construction specifications.
② the reinforcement joints of the same section shall not exceed 25% and shall be staggered.
⑥ in summer, when mixing concrete, ice or water shall be added to cool the aggregate to reduce the pouring temperature of concrete, or night pouring shall be used.
④ strictly control the mixing time of concrete.
(6) In order to prevent the collision and swing between the formwork and the reinforcement cage, the wind rope shall be set during the hoisting of the formwork to maintain the stability of the formwork during the hoisting process.
The thickness of the reinforced concrete protective layer shall meet the requirements of the design and specifications.
(2) Survey and setting out to determine the axis and elevation of bent cap.
Test pieces shall be selected according to the regulations for mechanical, chemical and weldability tests.
If the pump truck fails to continue pouring, replace the pump truck in time.
② The support is erected with bowl buckle frame.
4.0 construction process flow (Fig.
② the concrete shall be mixed centrally by the mixing plant, and the forced mixer shall be used for mixing the concrete.
When preparing concrete, determine the slump of concrete mixture according to the site conditions and construction conditions.
The strength and stiffness of the formwork shall meet the design and specification requirements.
⑤ the grade, diameter, number and spacing of reinforcement shall meet the design requirements.
③ during winter construction, thermal insulation measures shall be taken for the transmission pipe.
The formwork shall be adjusted and reinforced through internal and external support to make it stable.
The straightening and rust removal of reinforcement shall meet the following requirements: a.
I-beam is erected on the steel hoop, and sleepers are laid on the upper part of the I-beam as the construction platform.
shall be removed before use.
Firstly, according to the elevation and pier column size, two semicircular steel hoops are tightly hooped at the corresponding position of the column.
① Floor type support, i.e.
5.4 concrete construction (1) Concrete production ① the construction mix proportion shall be determined according to the mix proportion design of the laboratory and in combination with the moisture content of on-site sand and gravel materials, and the concrete shall be mixed strictly according to the construction mix proportion.
(3) Concrete pouring ① before concrete pouring, the concrete at the top of the pier column shall be roughened, and the formwork, reinforcement, embedded parts, as well as various machines, tools and equipment shall be inspected.
The treated construction area shall be flat and dense, with corresponding bearing capacity and no subsidence.
Click the above text to pay attention to our capping construction operation instruction 1.0.
Two channel steels are used as the beam for lifting the reinforcement framework, and the truck crane is used to lift it in place.
Welding can be used if necessary.
The concrete can be poured only after all conditions meet the requirements and all preparations are arranged.
At least 4 cushion blocks / m2 shall be set between the reinforcement and the formwork on the side and bottom of the member, and the cushion blocks shall be tied tightly with the reinforcement.
(3) Install the bottom formwork according to the measurement results.
The installation of side plates must ensure the perpendicularity, the linear straightness of the whole formwork and the section size of the upper opening of the pier cap.
Double sided adhesive tape shall be pasted at the joints of all formwork to prevent slurry leakage.
② each bent cap must be poured at one time without construction joints in the middle..
② the concrete is pumped into the mold by a concrete pump.
(4) The side formwork and end formwork shall be hoisted as a whole.
(2) Reinforcement installation: ① for low pier bent cap, it can be bound and formed on the laid bottom formwork after the bent cap bottom formwork is installed; for high pier bent cap, it can be bound and formed in the reinforcement yard and transported to the site.
When laying the bottom formwork, two layers of square timber shall be laid on the top of I-beam, and the elevation of bent cap bottom formwork shall be adjusted with wooden wedge.
After the erection of the support, carefully check whether each bearing part is padded and firm.
Water and aggregate shall be treated according to thermal engineering The heating temperature required for concrete pouring shall be determined through calculation and actual trial mixing.
The formwork must be polished clean before installation, and the release agent meeting the requirements shall be applied evenly to facilitate formwork removal.
In order to prevent the hoop from sliding down during formwork erection or concrete pouring, two layers of waterproof geotextile shall be padded inside the hoop, so as to increase friction, prevent corrosion inside the hoop from polluting the column surface, and effectively prevent column wear during disassembly and assembly of the hoop.
After the bottom formwork is assembled and installed, the automatic leveling level is used to accurately control the elevation and control the bottom formwork elevation within the allowable range of the design.
Sleepers shall be paved as the working platform (3) hoop type shall be adopted for the cantilever type.
Sponge strips shall be pasted at the joint of bottom formwork and pier column, and the pier top shall be roughened according to the measured elevation.
A rubber pad is added between the steel hoop and the column.
The moisture content of coarse and fine aggregates shall be strictly measured before mixing the concrete Rate, accurately measure the change of water content of coarse and fine aggregates caused by weather changes, so as to adjust the construction mix proportion in time.
The cement shall not be directly heated, but shall be transported into the greenhouse for preheating before use.
During the feeding process, the pumping speed shall be maintained Continuity.
During summer construction, the transmission pipe shall be covered, watered, padded or painted white.
The two steel hoops are connected with high-strength bolts.
B.
The column top elevation shall be measured and the hoop position shall be determined according to the hoop size.
The concrete mix proportion for construction in winter shall be adjusted, smaller water cement ratio and slump shall be selected, and admixtures shall be selected reasonably.
The reinforcement shall be straight without local bending, and the coiled reinforcement and bent reinforcement shall be straightened.
The bound or welded reinforcement shall be firm and the reinforcement position shall be accurate.
④ the thickness of the reinforcement The crossing points shall be bound firmly with iron wire.
Survey and setting out, determine the scope of foundation treatment, and tamp the soft foundation after replacement, rolling, hardening and filling.
(2) Transportation and molding of concrete ① the concrete is transported from the mixing plant to the pouring site by a transport tanker and mixed slowly during transportation; when the mixer truck arrives at the pouring site, rotate at a high speed for 20 ~ 30s, check the uniformity and slump of the concrete, and feed the concrete after it is qualified.
(5) After the formwork is erected, the elevation of the formwork control point shall be measured to determine the concrete pouring position.
4-1) Construction process flow chart of bent cap 5.0 construction methods and requirements 5.1 support erection (1) support types for cast-in-situ bent cap construction mainly include floor support type, hoop cantilever type, etc.
2.0 the preparation is based on technical code for construction of highway bridges and culverts, standard for quality inspection and evaluation of highway engineering, technical code for safety of highway engineering construction 3.0 scope of application and conditions are applicable to the construction of capping beams of highway bridges.
The split screw and the support in the formwork shall be set on the same plane.
The elevation of bent cap and suspended beam shall be adjusted with square timber.
If necessary, reduce the pumping speed to maintain the continuity of pumping.
If the time is insufficient, the mixture will not meet the uniform requirements, and if the time is too long, the mixture may produce segregation.
