1、附录：专业英语翻译 Discuss the construction temperature and crack of the concrete lightly The summary , through observation live for many years, through consulting the monograph about stress within the concrete, explain to concrete temperature reason , on-the-spot concrete control and measure , prevention of
2、 crack of temperature that crack produce. Keyword Concrete Temperature stress Crack Control The concrete occupies the important position in modern engineering construction. But today, the crack of the concrete is comparatively general, the cracks are nearly omnipresent in the science of bridge build
3、ing. Though we take various kinds of measures in constructing, careful, but the crack still occurs now and then. Tracing it to its cause, it is one of them incompletely that our change to concrete temperature stress pays attention to. In the large volume concrete, temperature stress and temperature
4、control are significant. This is mainly because of the reason of two respects. First of all, concrete often appear the temperature crack in not constructing, influence the globality and durability of the structure. Secondly, in the course of operating, the temperature change has remarkable influence
5、 that cant be ignored on the stress state of the structure. Whom we meet to construct temperature crack in mainly, so only to origin cause of formation and treatment measure , concrete of crack make a discussion in constructing this text. Reason of a crack Have many kinds of reasons to produce the c
6、rack in the concrete, it is mainly the changes of temperature and humidity, fragility and disparity of the concrete, and the structure is unreasonable, the raw materials not up to standard (if the alkali aggregate react), the template is out of shape, the foundation does not subside etc. evenly . Th
7、e cement emits a large amount of heat of hydration when the concrete is hardenned, inside temperature is rising constantly, cause the stress of drawing on the surface. In the course of lowering the temperature , is it congeal foundation pay restrain to mix always later stage, will present the stress
8、 of drawing within the concrete . Reducing of temperature can surface cause heavy stress of drawing very in concrete too. When these draw the stress and go beyond resisting the ability of splitting of concrete , namely will present the crack . A lot of inside humidity of concrete change very light o
9、r change relatively slow, surface humidity might change heavy the violent change takes placing. Such as maintaining thoroughly, when getting wetter when not doing,contract surface there arent deformation doing, often cause the crack too. The concrete is a kind of fragility material , tensile strengt
10、h is about 1/10 of the compression strength, is it carry on ones shoulder or back limit when draw out of shape to have *104 only , is it carry on ones shoulder or back limit location when stretch out of shape to there is *104 to add for a long time to add a short time. Because raw materials even, wa
11、ter dust than unstable, transport and build phenomenon of emanating of course, its tensile strength is not even in the same concrete, a lot of resist the ability of drawing very low, it is apt to present the weak position of the crack. Among armored concrete , draw stress to undertake by reinforcing
12、 bar mainly , concrete bear stress of keeping just. Or reinforcing bar mix if edge position gone to to congeal present the stress of drawing in the structure in plain concrete, must rely on the concrete oneself to bear . Require to avoid the stress of drawing or only very small stress of drawing app
13、ears of the the general design. But the concrete is cooled from maximum temperature to the steady temperature of operating period in constructing, often cause sizable to draw the stress within the concrete. The temperature stress can exceed other outsides and load the stresses caused sometimes, know
14、 change law , temperature of stress for carry on reasonable structural design and construct extremely important. Analysis of 2 temperature stresses Can be divided into following three stages according to the forming process of the temperature stress: (1)It is early: Build concrete is it is it over b
15、asically to send out heat to cement to begin , generally one one day by oneself. Two characteristics at this stage, first, the cement emits a large amount of heat of hydration, second , mix and congeal the changing sharply of elastic model quantity. Because of the change of elastic model quantity ,
16、form the remaining stress in the concrete in this period. (2)Middle period: Up till the concrete is cooled until stability temperature from cement send out heat function basically when expiring, in this period, the temperature stress is mainly because the cooling of the concrete and external tempera
17、ture change cause, these stresses and remnants stresses that is formed in early days are superposed , mix and congeal the elastic mould amount that goes to and does not change much during this period. (3)Later period: Operation period after the complete cooling of concrete. Temperature stress whethe
18、r external temperature change cause mainly, these stresses and first two kinds of remnants stresseses are changed and added . Can be divided into two kinds according to the reason why the temperature stress causes: (1)Spontaneous stress: There are not any restraint or totally static structure at the
19、 border, if inside temperature is non-linear distribution, temperature stress appearing because structure restrains from each other. For example, the body of mound of the bridge, the physical dimension is relatively large, surface temperature is low when the concrete is cooled, inside temperature is
20、 high, present the stress of drawing on the surface, present the stress of pressing in the middle. (2)Restrain the stress: All of the structure ones or it restrain external one some border,cant out of shape and stress not cause not free. Such as case roof beam roof concrete and guardrail concrete. T
21、his two kinds of temperature stresses draw back stresses caused to act on with the doing of concrete together frequently. It is a more complicated job to want to analyse the distribution , size of the temperature stress accurately according to known temperature. In case of great majority , need to r
22、ely on the model test or the number value to calculate. To is it make temperature stress have sizable limp to creep concrete, at the stress accounting temperature, must consider the influence that creep , calculate concretly that no longer states thinly here. Control and preventing the measure of th
23、e crack of 3 temperature For prevent crack , lighten temperature stress can from control temperature and is it is it set about to restrain terms from two to improve. The measure of controlling temperature is as follows: (1)Is it improve aggregate grade mix , is it do rigid concrete to spend , mix mi
24、xture to adopt, is it guide angry pharmaceutical or plastification pharmaceutical ,etc. measure in order to reduce cement consumption of concrete to add； (2)Add water or the water to cool the broken stone in order to reduce the temperature of building of the concrete while mixing and shutting the co
25、ncrete； (3)Reduce the thickness of building while building the concrete on hot day, utilize and build the aspect to dispel the heat； (4)Bury the water pipe underground in the concrete, enter the cold water to lower the temperature openly； (5)Stipulate rational form removal time, the temperature keep
26、s warm the surface while lowering suddenly, in case that the rapid temperature gradient takes place in the concrete surface； (6)The concrete with medium and long-term and exposed construction builds a piece of surface or thin wall structure, take the measure of keeping warm in cold season； The measu
27、re of improving condition of restraining is: (1)Divide and sew and divide one rationally ； (2)Prevent the foundation from rising and falling too big； (3)Rational arrangement construction process, prevent the too big discrepancy in elevation and side from exposing for a long time； In addition, improv
28、e the performance of the concrete and improve and resist the ability of splitting, strengthen maintenance , prevent the surface from being done and contracted , especially guarantee the quality of the concrete is very important to preventing the crack, should pay special attention to avoiding produc
29、ing and running through the crack , the globality resumed its structure after appearing is very difficult, so should rely mainly on preventing the emergence of the running through crack while constructing. In construction of concrete , for raise turnover rate of template , demand concrete form remov
30、al as soon as possible that build newly often. Should consider form removal time properly when concrete temperature is higher than the temperature, so as not to cause the superficial early crack of concrete. Building the early form removal newly, cause very large stress of drawing on the surface, th
31、e phenomenon that temperature is assaulted appears. Build initial stage in concrete, because heat of hydration is sent out, the surface causes sizable to draw the stress, surface temperature is also higher than temperature at this moment, remove the template at this moment , surface temperature is lowered suddenly, must cause temperature gradient , thus add and draw the stress on the surface , change and add with the heat of hydration stress, in addition, the concrete dries and contracts , the superficial stress of
