【正文】 定合理的拆模時間，充分發(fā)揮混凝土的“應(yīng)力松弛效應(yīng)”；混凝土拆模后，及時回填土，避免結(jié)構(gòu)側(cè)面長期暴露。常用的塑性材料有聚氯乙烯膠泥、塑料油膏、丁基橡膠等等；常用的剛性止水材料為聚合物水泥砂漿。三是選用能抑制堿骨料反應(yīng)的摻和料。裂縫的寬度受溫度變化影響較大，冬季較寬，夏季較窄。一般在干熱和大風(fēng)天氣裂縫較為常見，形狀多為中間寬、兩端細(xì)、互不連貫且長短不一，較長的裂縫可達(dá) 2m－ 3m，寬度可達(dá) ，嚴(yán)重影響混凝土的抗?jié)B性和耐久性。 關(guān)鍵詞：混凝土；裂縫；預(yù)防；處理 1 前言 建筑工程施工中，如果混凝土構(gòu)件出現(xiàn)裂縫，就會影響混凝土構(gòu)件的剛度和建筑物結(jié)構(gòu)的整體抵抗能力，即使裂縫的出現(xiàn)不會導(dǎo)致混凝土構(gòu)件的破壞或建筑物的倒塌，也會影響到建筑外觀，當(dāng)裂縫寬度超出一定限度時，也會造成鋼筋銹蝕，影響結(jié)構(gòu)構(gòu)件的耐久性能。原地基土必須密實(shí)、均勻，并達(dá)到設(shè)計要求的承載能力；回填土嚴(yán)格按規(guī)范規(guī)定分層夯實(shí)，達(dá)到設(shè)計要求的壓實(shí)系數(shù)。五是在混凝土中 摻加一定量的緩凝劑，推遲熱峰的出現(xiàn)時間。通常的處理措施是在裂縫的表面涂抹水泥漿、環(huán)氧膠泥或在混凝土表面涂刷油漆、瀝青等防腐材料，在防護(hù)的同時為了防止混凝土受各種作用的影響繼續(xù)開裂，采用在裂縫的表面粘貼玻璃纖維布的方法，當(dāng)混凝土表面裂縫數(shù)量較多，分布面較廣時，常采用增加一層水泥砂漿或細(xì)石混凝土整體面層的方法處理，同時整體面層內(nèi)宜配置雙向鋼絲網(wǎng)。 適當(dāng)選擇配合比，避免水 灰比、水泥用量、砂率過大、嚴(yán)格控制砂、石的含泥量，避免使用粉砂，以提高混凝土抗拉強(qiáng)度。 在工程施工中，一般采取的措施為：在混凝土施工時應(yīng)注意布點(diǎn)下料的位置盡量要少；振搗下層鋼筋時可輕輕地對上部鋼筋進(jìn)行振動，盡量減少上部鋼筋粘帶水泥漿；澆筑混凝土以前可對鋼筋及模板用水濕潤，降低鋼筋及模板的溫度；夏季混凝土澆筑盡量選在早晨或晚間溫度較涼爽時；施工時應(yīng)嚴(yán)格控制鋼筋的保護(hù)層厚度。 bulk structure, when concrete and the outside temperature difference, heat conservation, proper removal time by the Director, the temperature control at 25 ℃ or less. Prevention of structural concrete temperature cracking caused by external constraints, the general technical measures can be taken to the following aspects: 1,A selection of low heat or hot cement (such as slag cement, sulfate resistant cement, fly ash cement) in preparing the concrete。 summer concrete pouring as much as possible when the temperature is cooler morning or evening。 concrete in winter construction chlorine mixed with salt as early strength agent, Gaja nitrate should also be doped with rust inhibitor (1% 2% of the cement quality)。 mixing cement in the concrete amount of 5% 10% of the VEA concrete microexpanders to counteract the control concrete cracking due to shrinkage and cooling caused by concrete shrinkage. 7 ,dualcontrol puting measures taken before the pouring of concrete construction conditions and to be taken crack prevention control measures, calculate the maximum possible cooling contraction of tensile stress, when found to exceed the calculated age of concrete tensile strength, adjustment measures taken to control the stress within the allowable range。 additional support points on the ponent reinforcement。 避免降溫與干縮共同作用導(dǎo)致的應(yīng)力疊加；在混凝 土中摻加水泥用量5%10%的 VEA 混凝土微膨脹劑，以抵消由于干縮和降溫引起的混凝土收縮，控制混凝土開裂。在氣溫高、濕度低、風(fēng)速大的天氣應(yīng)及早覆蓋、噴水霧養(yǎng)護(hù)，并適當(dāng)延長養(yǎng)護(hù)時間。二是采用級配較好的砂石骨料配制混凝土。二是在保證混凝土強(qiáng)度的前提下。三是澆筑混凝土之前，將基層和模板均勻澆水濕透。中文 5153 字 附錄 A 論建筑工程中混凝土裂縫的預(yù)防與處理 作者：阿西夫四是及時覆蓋握料薄膜或者潮濕的草墊、麻片等，保持混凝土凝結(jié)前表面濕潤， 或者在混凝土表面噴灑養(yǎng)護(hù)劑等進(jìn)行養(yǎng)護(hù)。改善骨料級配，摻加粉煤灰或高效減水劑等來減少水泥用量。三是混凝土澆筑要振搗密實(shí)。加強(qiáng)混凝土表面的抹壓，但應(yīng)注意避免過分抹壓。 采取“雙控 計算 ”措施，即在澆筑混凝土前按施工條件和擬采取的防裂控制措施，計算可能產(chǎn)生的最大降溫收縮拉應(yīng)力，當(dāng)發(fā)現(xiàn)超過計算齡期的混凝土抗拉強(qiáng)度時，調(diào)整所采取的措施使應(yīng)力控制在允許范圍內(nèi)；混凝土澆筑后，應(yīng)根據(jù)實(shí)測溫度和溫度升降曲線，計算每階段降溫時混凝土累計拉應(yīng)力，當(dāng)其大于該齡期的混凝土抗拉極限強(qiáng)度時，應(yīng)采取保溫養(yǎng)護(hù)措施，使各階段降溫時混凝土的累計拉應(yīng)力小于該齡期混凝土允許的抗拉強(qiáng)度，以控制裂縫出現(xiàn)。 prestressed reinforcement in the ponent. Grouting, caulking block method Grouting method applies to the structural integrity of the influential or the repair of concrete cracks in the impermeable requirements, it is the use of pressure equipment will cementing material pressure concrete cracks cementing material hardened with concrete to form a whole, and thus play blocking the purpose of reinforcement. Commonly used in the cementing material grout, epoxy, methacrylate, polyurethane and other chemical caulking is the most monly used crack block, it usually gouges along the cracks, filling them with plastic or rigid sealing material in the slot. In order to achieve the purpose of closed cracks. Commonly used plastic material PVC clay, plastic ointment, butyl rubber, etc.。 concrete pouring should be based on the measured temperature and temperature lift curves to calculate each stage of cooling when the concrete tensile stress accumulated when its greater than the age of the concrete tensile ultimate strength heat conservation measures should be taken so that the accumulated tensile stress of concrete in various stages of cooling is less than allowed by the age of concrete tensile strength, to control the crack appears. More plex reasons concrete cracks, depending on the circumstances and conditions, to take one or several of the measures. settlement crack control Settlement cracks in the concrete surface along the long direction of horizontal reinforced through broad distribution of surface, usually in the form removal after the 3d7d appear, mainly due, if the concrete pouring, the aggregate particles sink, grout float, blocked by steel or embedded parts or aggregate, cause the concrete the construction, the general measures taken. Note the location of material distribution in the concrete construction should be as far as possible less。 slide template should ensure that the installation of the size and quality of construction Ruoyin some reason stopped sliding time too long, you should release the template and then sliding to prevent crack concrete. 6. Conclusion Types of concrete cracks in large construction projects, and is a mon phenomenon, its presence will not only affect the appearance of the building, will also affect the use of the building function and durability, severe cases will be a threat to people39。 dampened with water before pouring of concrete can be reinforced and the template, reduci