The construction technology applied in the hydraulic engineering is related to the stability and service life of the whole project, and it is necessary to consider the impact of the external environmental changes and water load bearing capacity on the building when carrying out the technical design, in which the application of reinforced concrete construction technology can enhance the stability of its structure and improve the use effect.
In the construction process, the formwork should be fixed first, and only under the premise of ensuring the stability of the formwork can the concrete be poured, thus ensuring that the concrete is fixed in the designed formwork and ensuring the shape and structural stability. The article mainly elaborates on three aspects of formwork construction, reinforcement construction and concrete construction.
Formwork construction technology in reinforced concrete construction
Before the construction of hydraulic engineering, the first thing to do is to build the formwork, although the application of the formwork for the entire project belongs to the auxiliary tools, but the stability of the entire building structure has a direct impact, especially in the application of reinforced concrete construction technology must first carry out the construction of the formwork project, and to ensure the quality of the formwork, so as to help smoothly carry out the subsequent work, the main need to pay attention to Construction details are as follows.
1, the choice of formwork materials must meet the construction requirements
Hydraulic engineering construction is different from the general building, to be able to resist the impact of the external environment, disaster weather and hydraulic bearing, so the construction template material needs to meet certain strength and stiffness requirements, and in the subsequent construction process does not deform. In the process of erecting and splicing the formwork, attention should be paid to avoid leaving gaps, thus reducing the phenomenon of slurry leakage.
The surface of the formwork needs to achieve a certain degree of flatness and finish to ensure that the surface of the concrete does not appear pockmarked when it is shaped. And in the formwork selection, you need to first select the right size of the formwork according to the entire water conservancy project construction and scale, the formwork support model should also match with it, in all aspects are qualified, the formwork can be put into use.
2, formwork installation must meet the requirements of safety and stability
After the template material is prepared, it should be assembled together according to the different characteristics of each template in accordance with the professional method. The quality requirement of formwork installation is to achieve the strength, stiffness and stability of the design and regulations.
If the formwork is installed directly on the subsoil, it should be ensured that the subsoil has sufficient strength and should be padded with certain support plates to ensure the stability of the formwork. The joints between the formwork and the formwork should not exceed the specified width, which is specified to be no leakage. Before the installation of the formwork is completed and the concrete is not poured, all the debris inside the formwork except the pre-built parts and reinforcement structure should be cleaned up.
3、Pay attention to the protection of finished products when removing the formwork
When the concrete has solidified to a certain strength, the formwork should be removed. At this time, the formwork removal requirements shall not damage the finished concrete, especially the surface and angles shall not be damaged. Removal of the formwork should pay attention to the first installed formwork to be removed later, the removed formwork should be cleaned up in time and properly installed or reused.
Reinforcing steel engineering technology in concrete construction
1, the inspection and storage of reinforcing steel
The reinforcing steel must have the factory certificate of conformity, and by re-inspection test, test report, to prove that its technical data in line with the provisions of the current national technical standards before acceptance. If the product does not have the factory certificate or copy procedures do not meet the requirements, or the material certificate does not match, the batch is not clear shall not be accepted, strictly prohibited to use.
Rebar raw materials should be stacked into the warehouse or shed; in the absence of conditions, should choose a higher terrain, solid soil, more flat open-air site stacking, in the warehouse or around the site, forming a certain drainage slope or digging drains, in order to facilitate the drainage of water. Under the rebar stack to pad sleepers, not less than 20cm from the ground; the use of stacking frame, easy to distinguish the different grades, grades and specifications of steel, and easy access.
2、The connection of reinforcing steel
The connection of reinforcing steel can be divided into tying lap, mechanical connection or welding. The type and quality of mechanical and welded joints should be in accordance with the provisions of the relevant national standards. The joint of the reinforcing steel should be set at the less stressed place, and fewer joints should be set on the same reinforcing steel. Axial tension and small eccentric tension bars of the longitudinal reinforcement shall not be tied lap joints.
When the diameter of the tensile reinforcement d>28mm and the diameter of the compression reinforcement d>32mm, should not be tied lap joints. The lap joints of adjacent longitudinal reinforcing bars in the same member should be staggered. The length of the connection section of the lap joint of reinforcement tying is 1.3 times the lap length, where the midpoint of the lap joint is located within the length of the connection section of the lap joint belongs to the same connection section.
Concrete engineering construction technology
1、Inspection of concrete raw materials
The cement delivered to the site, there should be the manufacturer’s factory certificate and quality test report, the use of units should be accepted for inspection, if necessary, for re-inspection. And should be in accordance with the strength level of the marked species, the manufacturer’s factory batch number are placed neatly, not mixed. Concrete of various raw materials should be qualified before use, concrete mixing floor meters must be measured accurately, before each shift weighing, should be weighed to set the zero point effect check, and by obtaining the opening certificate before concrete pouring.
2、Optimize the design ratio of concrete
Collect raw materials for trial mixing, reduce the amount of cement as much as possible, add Class I fly ash, control the water-cement ratio within the range allowed by the specification, and use the secondary mix for coarse aggregates. Adding the right amount of fly ash has a good effect on improving the concrete’s compatibility, lowering temperature rise, reducing shrinkage and improving erosion resistance. In order to avoid cracks, the use of low and medium strength bottom cement in the design makes full use of the late strength of the concrete. In the design of the engineering structure, special attention should be paid to reduce the degree of restraint of the structure.
3, do a good job of concrete placement, pounding and maintenance work
In the water conservancy project concrete pouring and other engineering concrete pouring construction technology methods and construction requirements are basically the same, only need to arrange and pouring order according to the actual situation. For some structures where construction joints cannot be left, the pouring should be done at one time. In the process of pouring, attention should be paid to the comprehensive and appropriate amount of pounding to ensure the compactness of the concrete. When the concrete is poured, the initial set to the corresponding maintenance, until the strength of the concrete to meet the design requirements.
Precautions for construction of reinforced concrete in hydraulic engineering
1、Preventive measures for plastic shrinkage cracks
The first is to choose the right material, generally choose a smaller dry shrinkage value, good strength of silicate or ordinary silicate cement. Strictly control the water-cement ratio example, mixed with high-efficiency water reducing agent to increase the strength of concrete, reduce the amount of water and cement. To cover a film on the surface of the concrete in time to ensure the humidity of the concrete, or spray curing agent on the surface of the concrete, etc. for maintenance.
2、Preventive measures of subsidence cracks
To ensure the stability of the foundation, the geological structure of loose soil should be compacted and reinforced before construction. To ensure that the formwork has sufficient strength and stiffness to ensure that the force of the foundation is uniform. The concrete should not be soaked by water in the process of pouring, and the removal of the formwork should be controlled within a certain time, and attention should also be paid to the sequence of removing the formwork. When erecting formwork on frozen soil, attention should be paid to taking certain preventive measures.
Water conservancy project construction, should ensure the stability of the finishing structure and the safety of the later use, so in the planning and design stage should grasp the quality of construction of three aspects, namely, formwork, reinforcement engineering and concrete engineering.
According to the scale of water conservancy construction and specific needs to determine the selection of materials and technology application of each link, the construction site management personnel and technical operators to do a good job of training, the entire construction process should increase supervision, according to the design plan and requirements of strict construction operations, the site staff to do a positive deployment of work, so as to ensure that the quality of water conservancy construction and construction time to meet the requirements.