According to the civil engineering of concrete structure crack control
Zhang in a green sea blue even design and research institute of civil room 222004
Abstract: the reinforced concrete structure has the very strong applicability, widely use of civil engineering. But due to the disadvantages of concrete itself, all kinds of civil engineering of the concrete structure is easy to appear structure crack. This is both civil engineering quality problems is also plagued the construction engineers and construction units of a difficult problem. Through analysis of civil engineering concrete structural cracks analysis of the causes, and combine these causes of cracks in the proposed control measures, so as to the actual project construction process help.
Keywords: civil engineering; Concrete structure; Crack; control
Civil engineering that is used for industrial and civil engineering construction. The materials, structural problems, carrying their construction time, weather conditions, humidity, temperature and other reasons, appear structure crack is the inevitable. But, if no cracks take measures to control, more than the maximum cracks of concrete structure will be the service life and safety of the negative impact of the, many have completed and put to use for the engineering fracture existence or expand to bring users of psychological negative effect. This also is at present not reasonable for crack control led to project is complaints and produce sounds quality one of the causes of the dispute. So, in civil engineering of the concrete structure construction process, analysis of mastery of the structure crack the disadvantage factors, timely reasonable measures to crack control and processing, can avoid for the structure of bearing caused cracks appear. Once appear inevitable crack to timely found out and remedial measures to achieve the design, construction and use requirement.
A, the causes of cracks in the concrete structure
The cracking of the concrete structure of reason basically has the following kinds: (a) with the loading shall be used for structure works directly from the body of the crack. The crack in the design structure have been calculated, when structure out under the effect of load deformation and cracking, should reconsider, should not be to design of equivalent stress state on view. The loading of the stress lead to excessive produce of crack is not belong to this a; (2) in the cracks of the concrete structure deformation. This is because the cracks of an engineering structures at room temperature and very body temperature to structural volume is not the same, the high temperature expansion contributes to structures by compression, once the freeze is difficult to restore; (3) engineering materials in the process of construction in accordance with the scientific construction method of no use in crack, it mainly appear in the high temperature environment construction engineering structures. The construction process of crack control but found the edge timely solve; (4) the foundation, etc to reverse displacement and stress non-uniform structure from the crack. The surface of the parallel displacement of structure will not influence. Once at the same time appear horizontal displacement and vertical displacement, engineering structures will be in two different under the direction of the force in reverse, crack, and it may be possible to expand the crack; (5) due to prevent structure stress and settlement body beforehand the cracks of the design, the cracks of the concrete structure is to the whole body safety, especially the security and design of the pedestal crack.
Second, the crack control measures and methods
Civil engineering construction period generally are very short, both must ensure the quality, and to ensure the safety of the design. To solve the problem of cracks can be realized through to the structure design of the body could predict of cracks and prevent calculated design and construction process of technology and the transformation of the control, the side found way to solve the edge.
(a) the modern civil engineering structure design generally have the transition to the computer model design
In the design of concrete structures to fully consider the model and the practical engineering construction with which, at the same time, the maximum allowed for crack of the model of the structure were also predicted.
First to concrete structures of columns and the situation of internal subdivision, for different length of beam and column combining site force of the scattered to do the design, avoid a structure stress and the other part too large a part too small force structure; The design of the structure of preventing the crack in all kinds of unknown to in construction in time on the computer can be modified and in the same problems encountered in the construction of the avoid; To control the in design of concrete frame the rigidity, high sure to root for each beam and the length of the column on the reasonable decorate, the greater the stiffness of the overall structure of the smaller than also grow taller, but according to actual condition is not possible to grow taller than all the same design small; For our country some areas surface structure is weak, the surface structure more for density is small of mud and sand foundation, and the civil engineering fully consider the settlement, ignore this of the consequences of not just crack, may have the whole project will collapse; On the foundation of the design, can use the increase of buried depth to buy foundation strengthen the basic structure of the stability and the stiffness to reduce cracks, through to the same project foundation strength design of the differences of foundation to the differences between the non-uniform deformation of foundation caused crack control; Finally, the earthquake, landslide and debris flow is prone to multiple areas of the civil engineering and design thinking by these geological disaster under the influence of the negative impact of the most could be influenced by the structure of the components on the strength of the increasing design.
(2) in the construction process on the crack prevention and control measures
1. Through the preparation for construction of the control to strengthen the control of crack
First of all to the quality of the construction of the construction unit evaluation, eliminate the use of construction qualification discrepancy of units for homework; To design the construction drawings for detailed to discuss and inspection work, the structure of the cracks of possible body parts and construction process of comprehensive HuiShen. A design to ensure that clear, no structure deformation of contraction, the structure of the pouring belt design and reasonable measures to strengthen the contraction of seam design, two to clear the strength of reinforced configuration, too thick and meticulous reinforced would give structure parts of the negative impact of the, third, we need to think about the big volume of concrete component to have enough reinforced bone pieces; The organization of construction of construction to reasonable control, fully consider the concrete construction technology and flow.
2. Through the construction process of strengthening the control of crack control
Control material, cement, coarse aggregate, fine aggregate and material choice of the additive must comply with the safety standards for material to the expansion of the materials, alkaline reaction to the material, the severe foam containing clay materials more sand, gap and quality of a material is not enough hard material to carefully distinguish, eliminate the use of substandard construction materials; Try to minimize the water consumption of construction materials, is prohibited in the process of concrete pouring water, in strict accordance with the ingredients of a fixed amount, no less to stir materials; The casting of concrete component template and reinforcing cage production must be in terms of quality and quantity strictly checks. Eliminate the use of low quality varieties of reinforcing steel bar and reinforced need to pass a quality and replacement of technical personnel detection and accounting may continue to construction. Casting template to often add check and prevent the loose, deformation, sink phenomenon to appear, etc. If appear several ways of one or more to timely through strengthening, thickening remedy.
3. Through the on construction site to strengthen the control of crack control
To strengthen the construction of the maintenance, the maintenance of concrete in time, to ensure the concrete water content, high temperature homework more to wireless concrete filling water; Embed pipe to strengthen the control of crack in of pipe interchange will through the crack of strengthening the pipeline steel implanted strength; The crack of construction to the clean up in time, ensure that different pouring concrete tight connection time; The most important point, the construction process of concrete used in white concrete thing to serious and careful vibrating, ensure the concrete things as concrete body evenly distributed. And at the same time grasp reinforced concrete of the same position, in order to ensure the concrete body stiffness even, in different temperature, humidity, wind speed cases according to the real-time situation on a body of early concrete curing.
Although in design, construction prevention, construction process and construction site control all steps have done well, to remedy of cracks in time, but there are still not avoid cracks appear, such as board face and bottom crack, long transfixion crack, etc. Faced with these, usually in decorating a process of hydraulic pressure grouting, besmear brushs closed, laying a steel wire nets concrete reinforcing, enhance fiber reinforced materials and high pressure encapsulating compound way enhancement processing, etc.
Concrete structure construction process is a complicated process, a link any negligence may be the construction quality of adverse effects. As long as the strengthening design, material management and use, the construction of strict execution and management, we can very well to avoid the cracking of the prevention and control and various.
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