【正文】 土內(nèi)部達(dá)到最高溫度后，熱量逐漸散發(fā)而達(dá)到使用溫度或最低溫度，它們與最高溫度的差值就是內(nèi)部溫差；這三種溫差都會(huì)產(chǎn)生溫度裂縫。 由于混凝土的抗拉強(qiáng)度很小，當(dāng)結(jié)構(gòu)或構(gòu)件的某一部分由于外部作用產(chǎn)生的拉應(yīng)力大于混凝土的抗拉強(qiáng)度時(shí)，就會(huì)出現(xiàn)裂縫。s shrinkage, the author thinks carefully select material, and in the use of reasonable construction method, can effectively prevent the cracks. 混凝土施工裂縫原因及防治 混凝土施工裂縫原因不外乎外因和內(nèi)因。 20 mm. To minimize the mouth 3 concrete temperature. (b) concrete mixing in a storehouse after good transport process, to prevent to produce separation, lactation water, mortar loss should shorten transportation time, concrete loading not too full. (2)Concrete pouring and open mode. Pouring process may be closegrained, vibration to vibration time should be uniform in surface functional plasma advisable, uniform spacing, vibrating force scope affected overlap 1/2 advisable, after casting, paction, surface must, in order to prevent the surface crack. Try to avoid in the solar radiation, high time due to the needs of the project if pouring in summer construction, avoid noon pouring temperature period, try to arrange at night. Time should be removed, according to air temperature and strength. In the actual temperature curing of the concrete conditions of strength, strength design of concrete center and 75%, the lowest temperature control surface in 25 degrees Celsius, expected the concrete surface temperature drop more than 9 degrees Celsius above does not allow removed. (3) Do surface insulation protection of mass concrete temperature crack, is mainly caused by excessive temperature. Concrete pouring, due to internal heat faster, more surface temperature will form the internal and external surface by internal restraint, contraction, but the tensile stress, not more than usually have small tensile strength and the concrete cracks. But if the air raid, or by excessive ventilation cooling, make the surface temperature will easily lead to excessive temperature crack in the concrete, and so on, especially after dismantling formwork, low season in the immediate surface protection. To prevent excessive temperature crack, cause surface. In addition, the average day temperature in 2 ~ 3d consecutive decline not less than 6 ~ 8 degrees Celsius, 28d age concrete surface must surface within the protection. (4) Of the mass concrete casting: Construction scheme, besides should satisfy each place of concrete in early before a new concrete are covered and rammed finished outside, still should consider structure size, steel pipe, buries the bolts and leave, concrete and hydration heat supply, the influence of factors such as the monly used method has the following kinds: Comprehensive stratified: In the first layer after pouring all prehensive casting, casting back second, should make the first layer of concrete yet, so early, continuous casting until pletion by far. Using this scheme, applicable to the general structure of planar size shoulds not be too big, when construction from the short side began to push along the long side, is more appropriate. When necessary, can be divided into two sections from middle to both ends to or from the middle and construction. Section 2 layer: Concrete casting, starting from scratch, casting a certain distance to the second floor, so after pouring in other layers on casting. Due to the total number of layers, therefore, after the first layer top pouring concrete yet at the end of the beginning of the second period, and can turn from layered casting. This scheme is applicable to units within the time required, the supply of concrete less like the first option on that. This scheme is applicable to structure is too big and thickness of large area or length. Incline stratified: Requirements of slope not greater than cant 1/3, applicable to greatly exceed the length of the structure of the thickness of the three times. From the bottom layer of concrete casting, gradually move. measures Maintenance