混凝土工冬季 施工方案
吉林市中百利呈建设工程有限公司
2015年2月2日
目 录
1.工程概况················································2 2.编制依据···············································2 3.施工准备················································2 3.1材料准备··············································2 3.2机具准备··············································2 3.3人员准备··············································2 3.4现场准备··············································2 3.5技术准备···············································3 4.施工方法················································3 4.1混凝土的拌制··········································3 4.2混凝土的运输···········································4 4.3混凝土的浇筑·········································4 4.4混凝土的养护·········································6 5.混凝土的测温···········································6 5.1测点布置原则·········································6 5.2测温方法·············································6 5.3测温要求·············································6 5.4大体积混凝土养护测温记录·····························6 5.5 混凝土拆模要求·······································7 6.冬季施工的质量通病以及预防措施 ························8 6.1 钢筋的锈蚀与混凝土裂缝·······························8
6.2 结构疏散与水分转移···································8 6.3 表面起灰·············································8 6.4 结晶腐蚀-混凝土表面返霜······························8 7.安全技术措施···········································8 8.质量保证措施···········································9
1 工程概况
本工程系吉林市城市建设控股集团有限公司开发的办公楼，位于吉林市重庆街南侧，中兴街东侧，总建筑面积约12万m2，其中地下二层，两层总建筑面积约为38080万m2，办公楼地下二层，地上25层，建筑面积约8.2万m2。
当室外日平均气温连续5d稳定低于5℃时，就应采取冬期施工的技术措施进行混凝土施工。混凝土所以能凝结、硬化并取得强度，是水泥和水进行水化作用的结果。水化作用的速度在一定湿度条件下主要取决于温度，温度愈高，强度增长也愈快，反之则慢。当温度降至0℃以下时，水化作用基本停止，温度再继续降至-2～-4℃，混凝土内的水开始结冰，水结冰后体积增大8%～9%，在混凝土内部产生冰晶应力，使强度很低的水泥石结构内部产生微裂纹，同时减弱了水泥与砂石和钢筋之间的粘结力，从而使混凝土后期强度降低。受冻的混凝土在解冻后，其强度虽然能继续增长，但已不能 再达到原设计的强度等级。
试验证明，混凝土遭受冻结带来的危害，与遭冻的时间早晚、水灰比等有关，遭冻时间愈早，水灰比愈大，则强度损失愈多，反之则损失少。
经过试验得知，混凝土经过预先养护达到一定强度后再遭冻结，其后期抗压强度损失就会减少。一般把遭冻结其后期抗压强度损失在5%以内的预养强度值定为“混凝土受冻临界强度”。对用普通硅酸盐水泥的硅酸盐水泥配制的混凝土，受冻临界强度为设计的混
凝土强度标准值的30%；对用矿渣硅酸盐水泥配制的混凝土，受冻临界强度定为设计的混凝土强度标准值的40%。 2 编制依据
1.《建筑工程冬期施工规程》JGJ104-97
2.《混凝土结构工程施工质量验收规范》GB50204-2002 3.《混凝土外加剂应用技术规范》GB50119-2003 4.《建筑施工技术》 3 施工准备 3.1 材料准备
3.1.1 水泥：水泥标号为P.O.42.5级的普通硅酸盐水泥。此种水泥水化热比较低，适合本工程使用。水泥进场时必须有质量证明书及复试试验报告，并对其品种、标号、包装、出厂日期等检查验收。 3.1.2 砂：选用质地坚硬、级配良好的中砂，含泥量不大于3%。 3.1.3 石子：粒径0.5～2.5cm的级配碎石，混凝土低于C30时，含泥量不大于2%。
3.1.4 混凝土外加剂：选用早强剂型复合防冻剂，并应有减水、引气作用，含气量应控制在2%～4%。 3.2 机具准备
主要冬施材料情况表
序号 1 2 3 冬施主要材料 聚乙烯塑料布 （0.8mm厚黑色） 塑料防水彩条布 保温草袋（草帘） 使用部位 梁、柱、板模板包裹封闭保温及板面覆盖 各层迎风面挡风封闭 各层板、柱、墙保温层 使用量 应明确数量 应明确数量 应明确数量
混凝土工程冬季施工方案
