严寒气候下的大体积混凝土施工工法

'严寒气候下的大体积混凝土施工工法一、特点（1）、严寒地区冬季气候特点严寒、冻结期长、大风、沙尘暴。（2）、严寒、冻结期长直接影响和混凝土施工质量，大风、沙尘暴直接影响施工的有序有效地开展。由于普通地区的养护施工方法远远不能满足高寒地区施工,为了保证混凝土施工质量，使混凝土强度顺利、迅速增长，保温养护工作和措施就显得尤为重要。（3）、大体积混凝土内外温差控制是指大体量混凝土水泥水化产生水化热所产生混凝土内外的温差。内外温差过大会使混凝土温度应力产生不均匀收缩变形导致裂缝，从而降低混凝土强度，所以必须予以控制这种裂缝现浇混凝土结构。（4）、采用一次整体浇注混凝土的方法和“综合温控”施工技术，有利于提高结构的混凝土强度和整体性，同时提高了结构的抗震能力。 （5）、打破常规大体积混凝土内部降温，而采取蒸汽养护提升混凝土环境温度和湿度来控制大体积混凝土内外温差。二、适用范围工业项目中超长、超厚现浇钢筋混凝土结构，如连续性基础底板、箱型基础、设备基础等需要裂缝控制的钢筋混凝土工程。三、施工要点1、保温暖棚的搭设应根据工程项目的平面形状尺寸、结构形式等不同情况，合理、经济地搭设保温暖棚。（内蒙古液化天然气项目LNG储罐基础为直径helpingbuildtheteam,setupanaccuratepovertyalleviationmechanisms,implementingtherequirementsofaccuratepovertyalleviation.Fouristheenterpriseattachesgreatimportancetopeople"slivelihood.Morelimitedfinancialresourcesonthepeople"slivelihood,activelypromotethedevelopmentofsocialundertakingssuchaseducation,medicalandhealth,completedthe"ten"sproject"strengtheningoflow-incomehousing,publicrentalhousing,renovateruralandearthquakeresistanthousingprojectstoimprovepeople"shousingconditions;furtherprosperityanddevelopmentofculturalundertakingsandculturalinheritance,protection,rescueanddevelopment.Fiveisfullyengagedintheurbanandruralenvironment.Workingcasuallyparkedvehicles,trash,litteringorabandoning,noiseisdisturbing,andsoon.CompletedtheTownshipresidentStreetsolarstreetlights,cleardrainssludge,constructionoflatrines,wasteincinerationpool,advancingstreetlighting,landscaping,cleaning,hardening,improveruralhumansettlementenvironment.Thesixareworkingtogethertofightagainstnaturaldisasters.Torespondcalmlyandproperly"8.05"wangjiduVillageand"8.20"ancientvillagetorrentdebrisflowdisasters.Beforethedisaster,andtownshipPartyCommitteeteammembers,partymembersandcadresreservemilitia,armedpoliceofficersandmen,thecouragetodashthedangerzone,daredto 19.82米、基础高2.9米、基础埋深1.3米，采用φ48×3.5钢管扣件搭设暖棚骨架，外墙采取环行双排脚手架，钢管搭设桁架式屋盖，屋盖中心环下采取双钢管立柱支撑。然后根据此骨架，采用加工厂加工定做的方式，定做保温棉布进行遮盖围护，以形成封闭空间并且对封闭空间内的所有洞口进行封闭，从而避免内外冷暖空气对流，以达到保温和蓄热效果。）2、混凝土材料要求（1）水泥：应尽可能采用中低水化热的水泥。如采用325号（C30以下）、425号（C30及以上）矿渣硅酸盐水泥。为减少水泥用量，降低水化热。（2）细骨料：中粗砂，含泥量<2%。（3）粗骨料：5~25mm或5~40mm石子，优先选用5~40mm石子（自拌），减少混凝土收缩。含泥量<1%，符合筛分曲线要求。骨料中针状和片状<15%（重量比）。（4）外掺剂：在混凝土中可掺加复合型外加剂和粉煤灰，以减少绝对用水量和水泥用量，改善混凝土和易性与可泵性，延长缓凝时间。（5）模板：宜采用组合钢模。采取蒸汽养护，钢模传热比较快。3、混凝土配合比：采用集料泵送混凝土砂率应在40%~45%之间，在满足可泵性的前提下，尽量降低砂率。坍落度在满足泵送的条件下尽量取小值，以减少混凝土的收缩变形。4、控制新鲜混凝土的出机温度：混凝土中的各种原材料，尤其是石子与水，对出机温度影响最大。冬季新鲜混凝土出机热量散失比较大，helpingbuildtheteam,setupanaccuratepovertyalleviationmechanisms,implementingtherequirementsofaccuratepovertyalleviation.Fouristheenterpriseattachesgreatimportancetopeople"slivelihood.Morelimitedfinancialresourcesonthepeople"slivelihood,activelypromotethedevelopmentofsocialundertakingssuchaseducation,medicalandhealth,completedthe"ten"sproject"strengtheningoflow-incomehousing,publicrentalhousing,renovateruralandearthquakeresistanthousingprojectstoimprovepeople"shousingconditions;furtherprosperityanddevelopmentofculturalundertakingsandculturalinheritance,protection,rescueanddevelopment.Fiveisfullyengagedintheurbanandruralenvironment.Workingcasuallyparkedvehicles,trash,litteringorabandoning,noiseisdisturbing,andsoon.CompletedtheTownshipresidentStreetsolarstreetlights,cleardrainssludge,constructionoflatrines,wasteincinerationpool,advancingstreetlighting,landscaping,cleaning,hardening,improveruralhumansettlementenvironment.Thesixareworkingtogethertofightagainstnaturaldisasters.Torespondcalmlyandproperly"8.05"wangjiduVillageand"8.20"ancientvillagetorrentdebrisflowdisasters.Beforethedisaster,andtownshipPartyCommitteeteammembers,partymembersandcadresreservemilitia,armedpoliceofficersandmen,thecouragetodashthedangerzone,daredto 同时考虑到运送距离比较远，混凝土在运送过程中热量损失大，宜在砂石堆场设置蒸汽锅炉，对骨料和水进行加热提高混凝土出机温度等措施。5、控制浇注入模温度：冬季施工对混凝土罐车进行保温并在输送泵送时采取保温措施，以保证混凝土入模温度在10℃以上。6、混凝土的施工：（1）混凝土浇筑顺序的安排：采取薄层连续浇筑延长浇筑间隙时间以利散热，以不出现冷缝为原则。（2）宜尽可能采用二次振捣工艺，以提高混凝土密实度和抗拉强度，对大面积的板面要进行拍打振实，去除浮浆，采取二次抹面，以减少混凝土表面的收缩裂缝。（3）混凝土在浇筑振捣过程中出现的泌水应及时排除。（4）根据大体积混凝土的施工特点和施工经验，实时测量混凝土内部中心与表面温度差，宜控制在25度之内。（5）利用测温技术进行施工，可以全面了解混凝土在强度发展过程中内部温度场分布状况，并根据温度梯度变化情况，实时指导施工，控制降温速率，控制裂缝的出现。7、测温（1）应根据工程项目的平面形状尺寸、厚度等不同情况，合理、经济地布设测温点，并测绘测温点布置图。（helpingbuildtheteam,setupanaccuratepovertyalleviationmechanisms,implementingtherequirementsofaccuratepovertyalleviation.Fouristheenterpriseattachesgreatimportancetopeople"slivelihood.Morelimitedfinancialresourcesonthepeople"slivelihood,activelypromotethedevelopmentofsocialundertakingssuchaseducation,medicalandhealth,completedthe"ten"sproject"strengtheningoflow-incomehousing,publicrentalhousing,renovateruralandearthquakeresistanthousingprojectstoimprovepeople"shousingconditions;furtherprosperityanddevelopmentofculturalundertakingsandculturalinheritance,protection,rescueanddevelopment.Fiveisfullyengagedintheurbanandruralenvironment.Workingcasuallyparkedvehicles,trash,litteringorabandoning,noiseisdisturbing,andsoon.CompletedtheTownshipresidentStreetsolarstreetlights,cleardrainssludge,constructionoflatrines,wasteincinerationpool,advancingstreetlighting,landscaping,cleaning,hardening,improveruralhumansettlementenvironment.Thesixareworkingtogethertofightagainstnaturaldisasters.Torespondcalmlyandproperly"8.05"wangjiduVillageand"8.20"ancientvillagetorrentdebrisflowdisasters.Beforethedisaster,andtownshipPartyCommitteeteammembers,partymembersandcadresreservemilitia,armedpoliceofficersandmen,thecouragetodashthedangerzone,daredto 2）温度测点以集成温度传感器作感温元件，要进行筛选和防老化处理。在埋设前应对感温元件作环氧树脂封闭。在浇注前应按测温布置图要求，对测点予以固定和保护，以确保测温工作的顺利进行。（3）每次测温后，应立即汇总整理混凝土内部温度场与混凝土内外温差数值，提供给施工指挥部门，以指导现场的施工。8、养护养护是大体积混凝土施工中一项十分关键的工作。养护主要是保持适宜的温度和湿度，以便控制混凝土内表温差，促进混凝土强度的正常发展及防止混凝土裂缝的产生和发展。严寒地区冬季施工宜采用蒸汽养护，在保温暖棚内混凝土侧模及顶部用无缝钢管制作蒸汽喷管使混凝土表面受热均匀，同时在喷管外用塑料薄膜搭设蒸汽养护罩。当混凝土浇筑完后，封闭养护罩，通入蒸汽提升混凝土养护环境温度，实时监控混凝土内外温差。当混凝土强度达到1.2MPa后，在混凝土表面进行蓄水养护并加盖塑料薄膜覆盖。养护必须根据混凝土内表温差和降温速率，及时调整养护措施。四、施工工序helpingbuildtheteam,setupanaccuratepovertyalleviationmechanisms,implementingtherequirementsofaccuratepovertyalleviation.Fouristheenterpriseattachesgreatimportancetopeople"slivelihood.Morelimitedfinancialresourcesonthepeople"slivelihood,activelypromotethedevelopmentofsocialundertakingssuchaseducation,medicalandhealth,completedthe"ten"sproject"strengtheningoflow-incomehousing,publicrentalhousing,renovateruralandearthquakeresistanthousingprojectstoimprovepeople"shousingconditions;furtherprosperityanddevelopmentofculturalundertakingsandculturalinheritance,protection,rescueanddevelopment.Fiveisfullyengagedintheurbanandruralenvironment.Workingcasuallyparkedvehicles,trash,litteringorabandoning,noiseisdisturbing,andsoon.CompletedtheTownshipresidentStreetsolarstreetlights,cleardrainssludge,constructionoflatrines,wasteincinerationpool,advancingstreetlighting,landscaping,cleaning,hardening,improveruralhumansettlementenvironment.Thesixareworkingtogethertofightagainstnaturaldisasters.Torespondcalmlyandproperly"8.05"wangjiduVillageand"8.20"ancientvillagetorrentdebrisflowdisasters.Beforethedisaster,andtownshipPartyCommitteeteammembers,partymembersandcadresreservemilitia,armedpoliceofficersandmen,thecouragetodashthedangerzone,daredto 保温暖棚搭设垫层施工小型蒸汽锅炉安装暖气散热片安装钢筋安装模板安装混凝土施工蒸汽养护降温实时测温五、质量标准混凝土施工及裂缝控制等质量标准，按现行施工规范中的有关规定执行。六、机具设备1、结构支模、扎筋、混凝土拌制、运输、浇筑、脚手架搭设、蒸汽锅炉安装等所需的机具设备，可根据不同工程对象按通常施工要求设置。2、测温设备采用铜热电阻集成温度传感器，大体积混凝土温度微机实时监测仪。条件不容许的情况下，可采取人工采集温度数据。3、可根据搭设保温暖棚内部空间大小选择蒸汽锅炉的大小。七、劳动组织及安全helpingbuildtheteam,setupanaccuratepovertyalleviationmechanisms,implementingtherequirementsofaccuratepovertyalleviation.Fouristheenterpriseattachesgreatimportancetopeople"slivelihood.Morelimitedfinancialresourcesonthepeople"slivelihood,activelypromotethedevelopmentofsocialundertakingssuchaseducation,medicalandhealth,completedthe"ten"sproject"strengtheningoflow-incomehousing,publicrentalhousing,renovateruralandearthquakeresistanthousingprojectstoimprovepeople"shousingconditions;furtherprosperityanddevelopmentofculturalundertakingsandculturalinheritance,protection,rescueanddevelopment.Fiveisfullyengagedintheurbanandruralenvironment.Workingcasuallyparkedvehicles,trash,litteringorabandoning,noiseisdisturbing,andsoon.CompletedtheTownshipresidentStreetsolarstreetlights,cleardrainssludge,constructionoflatrines,wasteincinerationpool,advancingstreetlighting,landscaping,cleaning,hardening,improveruralhumansettlementenvironment.Thesixareworkingtogethertofightagainstnaturaldisasters.Torespondcalmlyandproperly"8.05"wangjiduVillageand"8.20"ancientvillagetorrentdebrisflowdisasters.Beforethedisaster,andtownshipPartyCommitteeteammembers,partymembersandcadresreservemilitia,armedpoliceofficersandmen,thecouragetodashthedangerzone,daredto 1、劳动力情况可根据工程施工作业面的大小、结构形式和混凝土的浇筑顺序，以及混凝土的泵送能力等因素合理安排混凝土浇筑过程中使用劳动力人员数量。养护阶段可以按照二班或三班制昼夜值班，主要以监控温差等技术人员为主。2、安全本工法应严格遵守有关建筑安装企业施工的安全标准。以下几点尤为重要：（1）、蒸汽锅炉的安装、使用需要报检当地安监、锅检部门备案。（2）、暖气片选用与安装参照《新型散热器的选用与安装》图集号05K405。（3）、现场临时用电必须实行“三相五线”制，用电设备必须安装防漏电保护器，一机一闸一保护。固定电源线要尽可能架空，无法架空时，须采用防水橡胶电缆，拖地电缆必须符合耐压要求，严格禁止使用已老化的电缆或不合格品。八、工程实例内蒙古巴彦淖尔市位于中国北疆，内蒙古自治区西部。该地区属于典型的干旱半干旱大陆性气候，其特点是降雨量少而集中，蒸发强烈，干燥多风昼夜温差大。根据磴口县的气象站实时资料，2009年11月至2010年的3月底为冻结期，平均温度在零下15℃左右，最低温度零下26℃，风力平均4级以上时常风力达7级以上并伴随有沙尘暴天气。地表最大冻结深度为0.80m。helpingbuildtheteam,setupanaccuratepovertyalleviationmechanisms,implementingtherequirementsofaccuratepovertyalleviation.Fouristheenterpriseattachesgreatimportancetopeople"slivelihood.Morelimitedfinancialresourcesonthepeople"slivelihood,activelypromotethedevelopmentofsocialundertakingssuchaseducation,medicalandhealth,completedthe"ten"sproject"strengtheningoflow-incomehousing,publicrentalhousing,renovateruralandearthquakeresistanthousingprojectstoimprovepeople"shousingconditions;furtherprosperityanddevelopmentofculturalundertakingsandculturalinheritance,protection,rescueanddevelopment.Fiveisfullyengagedintheurbanandruralenvironment.Workingcasuallyparkedvehicles,trash,litteringorabandoning,noiseisdisturbing,andsoon.CompletedtheTownshipresidentStreetsolarstreetlights,cleardrainssludge,constructionoflatrines,wasteincinerationpool,advancingstreetlighting,landscaping,cleaning,hardening,improveruralhumansettlementenvironment.Thesixareworkingtogethertofightagainstnaturaldisasters.Torespondcalmlyandproperly"8.05"wangjiduVillageand"8.20"ancientvillagetorrentdebrisflowdisasters.Beforethedisaster,andtownshipPartyCommitteeteammembers,partymembersandcadresreservemilitia,armedpoliceofficersandmen,thecouragetodashthedangerzone,daredto 我公司于2009年12月至2010年3月在内蒙古巴彦淖尔华油天然气磴口县30×104Nm3/d液化天然气项目两台LNG储罐基础冬季施工中采用本工法分别组织进行一次性浇筑890m3混凝土施工，效果良好。本项目冬季施工是巴彦淖尔地区第一个成功冬季施工案例，冬季施工的特点代表性很强具有借鉴价值。helpingbuildtheteam,setupanaccuratepovertyalleviationmechanisms,implementingtherequirementsofaccuratepovertyalleviation.Fouristheenterpriseattachesgreatimportancetopeople"slivelihood.Morelimitedfinancialresourcesonthepeople"slivelihood,activelypromotethedevelopmentofsocialundertakingssuchaseducation,medicalandhealth,completedthe"ten"sproject"strengtheningoflow-incomehousing,publicrentalhousing,renovateruralandearthquakeresistanthousingprojectstoimprovepeople"shousingconditions;furtherprosperityanddevelopmentofculturalundertakingsandculturalinheritance,protection,rescueanddevelopment.Fiveisfullyengagedintheurbanandruralenvironment.Workingcasuallyparkedvehicles,trash,litteringorabandoning,noiseisdisturbing,andsoon.CompletedtheTownshipresidentStreetsolarstreetlights,cleardrainssludge,constructionoflatrines,wasteincinerationpool,advancingstreetlighting,landscaping,cleaning,hardening,improveruralhumansettlementenvironment.Thesixareworkingtogethertofightagainstnaturaldisasters.Torespondcalmlyandproperly"8.05"wangjiduVillageand"8.20"ancientvillagetorrentdebrisflowdisasters.Beforethedisaster,andtownshipPartyCommitteeteammembers,partymembersandcadresreservemilitia,armedpoliceofficersandmen,thecouragetodashthedangerzone,daredto helpingbuildtheteam,setupanaccuratepovertyalleviationmechanisms,implementingtherequirementsofaccuratepovertyalleviation.Fouristheenterpriseattachesgreatimportancetopeople"slivelihood.Morelimitedfinancialresourcesonthepeople"slivelihood,activelypromotethedevelopmentofsocialundertakingssuchaseducation,medicalandhealth,completedthe"ten"sproject"strengtheningoflow-incomehousing,publicrentalhousing,renovateruralandearthquakeresistanthousingprojectstoimprovepeople"shousingconditions;furtherprosperityanddevelopmentofculturalundertakingsandculturalinheritance,protection,rescueanddevelopment.Fiveisfullyengagedintheurbanandruralenvironment.Workingcasuallyparkedvehicles,trash,litteringorabandoning,noiseisdisturbing,andsoon.CompletedtheTownshipresidentStreetsolarstreetlights,cleardrainssludge,constructionoflatrines,wasteincinerationpool,advancingstreetlighting,landscaping,cleaning,hardening,improveruralhumansettlementenvironment.Thesixareworkingtogethertofightagainstnaturaldisasters.Torespondcalmlyandproperly"8.05"wangjiduVillageand"8.20"ancientvillagetorrentdebrisflowdisasters.Beforethedisaster,andtownshipPartyCommitteeteammembers,partymembersandcadresreservemilitia,armedpoliceofficersandmen,thecouragetodashthedangerzone,daredto'