【正文】 dmixtures, and easy to find flat surfaces to form a micromembrane to reduce evaporation and reduce drying shrinkage. Many have a retarding admixture to increase the workability and improve the function of plasticity, we in engineering practice in this area should be more contrast and research experiments than simply relying on external conditions to improve may be even more simple and economic. 4. early concrete conservation Practice has proved that the mon concrete cracks, the majority of surface cracks at different depths, mainly because of the temperature gradient caused by the cold temperature region is also vulnerable to a sharp fall in the formation of cracks. Insulation so that the concrete surface to prevent early cracking is particularly important. Thermal stress from the point of view, the insulation should meet the following requirements: 1) to prevent the concrete inside and outside the concrete surface temperature difference and gradient, to prevent surface cracks. 2) to prevent the concrete supercold, it should be possible to make concrete the construction period of not less than the minimum temperature of concrete used for the stability of the temperature. 第 111 頁(yè) 3) to prevent coldold concrete in order to reduce the concrete between the old and new constraints. Early concrete conservation, the main objective is to maintain the appropriate temperature and humidity conditions in order to achieve the effect of two aspects, on the one hand, the concrete from adverse temperature and humidity deformation invasion to prevent the harmful and drying shrinkage. On the one hand, to enable the smooth progress of cement hydration, with a view to meet the design capacity of the strength and crack resistance. Appropriate conditions of temperature and humidity are interrelated. Coagulation on the insulation often has the effect of moisture. Theoretical analysis of fresh concrete contained in the water fully meets the requirements of cement hydration and more than. However, due to evaporation and other factors often cause water loss, thereby delay or prevent the hydration of cement, concrete surface and most likely to be directly affected by such a negative impact. Concrete pouring, therefore the first few days after the critical period of conservation in the construction should pay attention to. 5. concluding remarks Above the temperature of concrete and cracks in the construction of the relation between theory and practice of the preliminary study, although the academic munity about the causes of cracks in concrete and calculation methods are different theories, but specific measures to prevent and improve the opinion it is quite uniform At the same time, the application in practice is also a relatively good effect, concrete construction and more depends on our observation, and more, when pared to multiissue analysis, and more sum up, bined with a wide range of prevention measures, the cracks in the concrete is pletely avoided 第 112 頁(yè) 中文翻譯： 混凝土施工溫度與裂縫 的探討 摘要：對(duì)施工中混凝土裂縫的成因進(jìn)行了探討，分析了混凝土的溫度應(yīng)力，詳細(xì)闡述了溫度應(yīng)力的控制和防止裂縫的措施，以避免混凝土產(chǎn)生裂縫，從而保證混凝土的施工質(zhì)量。由于遇到的主要是施工中的溫度裂縫，因此下面僅對(duì)施工中混凝土裂縫的成因 和處理措施做一探討。氣溫的降低也會(huì)在混凝土表面引起很大的拉應(yīng)力。混凝土是一種脆性材料，抗拉強(qiáng)度是抗壓強(qiáng)度的 1／ 10 左右，短期加荷時(shí)的極限拉伸變形只有（ ～ ）104 ，長(zhǎng)期加荷時(shí)的極限位伸變形也只有（ ～ ） 104. 由于原材料不均勻，水灰比不穩(wěn)定，及運(yùn)輸和澆筑過(guò)程中的離析現(xiàn)象，在同一塊混凝土中其抗拉強(qiáng)度又是不均勻的，存在著許多抗拉能力很低，易于出現(xiàn)裂縫的薄弱部位。但是在施工中混凝土由最高溫度冷卻到運(yùn)轉(zhuǎn)時(shí)期的穩(wěn)定溫度，往往在混凝土內(nèi)部引起相當(dāng)大的拉應(yīng)力。由 第 113 頁(yè) 于彈性模量的變化，這一時(shí)期在混 凝土內(nèi)形成殘余應(yīng)力。 根據(jù)溫度應(yīng)力引起的原因可分為兩類： （ 1）自生應(yīng)力：邊界上沒(méi)有任何約束或完全靜止的結(jié)構(gòu)，如果內(nèi)部溫度是非線性分布的，由于結(jié)構(gòu)本身互相約束而出現(xiàn)的溫度應(yīng)力。這兩種溫度應(yīng)力往往和混凝土的干縮所引起的應(yīng)力共同作用。 3． 溫度的控制和防止裂縫 的措施 為了防止裂縫，減輕溫度應(yīng)力可以從控制溫度和改善約束條件兩個(gè)方面著手。新澆筑早期拆模，在表面引起很大的拉應(yīng)力，出現(xiàn) “ 溫度沖擊 ” 現(xiàn)象。在溫度不太高及應(yīng)力低于屈服極限的條件下，鋼的各項(xiàng)性能是穩(wěn)定的，而與應(yīng)力狀態(tài)、時(shí)間及溫度無(wú)關(guān)。而且如果鋼筋的直徑細(xì)而間距 密時(shí)，對(duì)