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1、 泵送混凝土生产质量控制摘要文章主要阐述泵送混凝土生产过程中对原材料选择和控制、掺合料的掺量、外加剂掺量、浇筑过程及养护的控制以及工程应用效果。 关键词泵送；混凝土；原材料；质量；控制；养护；工程应用 作者简介廖德贵，广西电网公司桂林培训中心(桂林电力宾馆)总工程师，广西桂林，541002 中图分类号TU528 文献标识码A 文章编号1007-7723(2009)08-0123-0003 一、引言 当前，全国各地的基础设施建设正在轰轰烈烈地进行着。在所有的基础设施建设中，混凝土生产质量的控制成了关键，随着施工技术的不断发展，泵送混凝土的生产过程控制、施工工艺日趋先进，管理水平日趋科学化。所谓泵
2、送混凝土就是通过专用混凝土输送泵和管道靠泵压力将混凝土直接输送到浇筑点，这是业内人士众所周知的，勿需多述。但是如要完全控制好混凝土浇筑的全过程，进一步提高混凝土浇筑过程的施工效率，提高混凝土的质量，还必须从混凝土配合比设计的原材料、计量下料等细节进行控制；还有，混凝土的养护是获得优质混凝土不可缺少的部分，否则很难获得优质的混凝土产品。笔者多年来从事火电厂建设、民用设施建设，积累了一点经验，现就泵送混凝土生产质量控制的有关问题与大家共同探讨。 二、泵送混凝土原材料控制 (一)水泥 应确定水泥的品种、密度、表比面积、标准稠度用水量、已含矿物掺和料品种及含量、水化热、细度、凝结时间。泵送混凝土应选用
3、硅酸盐水泥、普通硅酸盐水泥、矿渣硅酸盐水泥和粉煤灰硅酸盐水泥，不宜采用火山灰质硅酸盐水泥。水泥品质应符合现行的国家标准GB/T175，选用的水泥强度应与混凝土的设计强度相适应，水泥产品一定要进行双控，采购入库的水泥在取得出厂合格证的同时，还应在出库前送试验室检验，检验合格后方可投入使用，同时确认各组分的含量是否发生较大变化，以便及时调整配合比。如：已含矿物掺和料含量发生变化时，应调整混凝土配合比中矿物掺和料的掺量，确保矿物掺和料占胶凝材料总量的比例不变，以保证混凝土的可泵性。 (二)砂子 确定砂子产地、松散堆积密度、表观密度、5mm以上颗粒的含量、氯离子含量、含水量等。泵送混凝土宜采用中砂，筛
4、除5mm以上颗粒后的细度模数应在2.3至3.0之间，其通过0.315mm筛孔的颗粒含量不应少于15。 当氯离子含量超标时，会对钢筋有锈蚀作用，最终破坏钢筋混凝土的使用寿命；当含水量发生变化时，应调整混凝土搅拌时的加水量，以确保水胶不变；当5mm以上颗粒的含量发生变化时，应调整石子用量，以保证混凝土的浆骨比不变。一般泵送混凝土的砂率不宜小于35，并不宜大于45。 (三)粗骨料 确定粗骨料品种、最大粒径、颗粒级配、级配后的空隙率等。 粗骨料宜采用连续级配，其针片状颗粒含量不宜大于10，其最大粒径不得超过钢筋间距的23、构件断面最小边长的14、混凝土板厚的12，同时不应超过管径的14，其空隙率应充分
5、给予重视，以不同粒径的二级配或三级配后的松散堆积密度空隙率不大于42为宜，在水胶比和浆骨比一定的条件下，砂石比的变动主要可影响施工性和变形性质，对硬化后的强度也会有影响。 (四)掺和料 确定其品种、密度、细度、烧失量、需水量比等。 泵送混凝土宜掺用粉煤灰或其他活性矿物掺和料，其质量应符合国家现行有关标准的规定。掺用矿物掺和料，既可以节约成本减少水泥用量，又能减少混凝土与管壁的摩擦，改善混凝土的可泵性，对混凝土的后期强度也有所改善。选择掺和料时，应着重关注掺和料的细度和需水量比。这两个因素控制不好，会给混凝土的强度和可泵性带来不利影响。矿物掺和料的掺量应根据工程性质、环境和施工条件来确定。一般泵
6、送混凝土的水泥和矿物掺和料的总量不宜少于300kgm3，对于地下和水下工程，尤其是大体积工程，矿物掺和料可用到最大掺量。 (五)外加剂 确定其品种、浓度、减水剂的减水率、引气剂的引气量等。 泵送混凝土应掺用泵送剂或减水剂，掺用泵送剂或减水剂，应根据施工需要及对混凝土性能要求、建筑物所处环境条件，适当选用相应性能的外加剂。只有选择合理的外加剂，才可改善混凝土的和易性、提离可泵性，合理降低混凝土中水泥用量，否则会适得其反。外加剂的掺量不能只凭其说明书上描述的掺量范围随意掺(占水泥质量的0.52.5，这个也太大了，其实它是针对多种水泥而言)，一旦确定了所用水泥的品种、牌号、强度等级，就必须经过试验，
7、找到其与所用水泥的最佳掺量。只有这样，外加剂才能发挥出它特有的功效，这才是我们所期望的。 当使用液体外加剂时，建议用部分已计量好的水将外加剂稀释，然后再加入到搅拌机里已搅拌均匀的水泥、掺和料、砂子、石子的混合物上；当使用粉剂外加剂时，可用部分已计量好的水将外加剂溶解，必须搅拌均匀，或者将粉剂外加剂与已计量好的水泥混合均匀后，然后加入到搅拌机中。 不能使用已变质的减水剂，有的外加剂有沉淀产生，但经过搅拌仍可用的，不属于变质范围。 当掺用引气型外加剂时，其混凝土含气量不宜大于4。 (六)拌和用水 一般应采用可饮用的自来水或洁净的淡水。 三、混凝土拌和物生产控制 (一)计量 生产过程中，必须保证原材
8、料称量的准确，建议每个台班应不少于一次校准，并严格控制各原材料称量的允许偏差值，每盘用料称量偏差一般控制如表1。 (二)水胶比 水胶比是影响混凝土强度的最主要因素，在水泥强度相同的条件下，混凝土强度随着水胶比的增大而降低。因此，拌制混凝土时应严格按照试验室出具的混凝土配合比设计报告进行配料，严禁随意更改水胶比。泵送混凝土的水胶比不宜大于0.60。 (三)坍落度 泵送混凝土坍落度一般控制在160200mm。坍落度损失后仍为140180mm左右，管道出口坍落度一般在120mm左右。现场施工时，应当根据泵送的水平距离、竖直距离、浇筑地点、浇筑部位选择适当的坍落度。因为坍落度过小，会造成泵送困难甚至堵
9、管；坍落度过大，不但浪费水泥，而且质量不易控制，还容易产生泌水或离析，对可泵性反而不利。 (四)试验1实内混凝土的搅拌时间实验室内混凝土的搅拌时间按表2控制。 当掺用外加剂时，搅拌时间应适当延长至180s。在混凝土搅拌站，当材料稳定时，混凝土的搅拌时间一般为90s，同时还应根据混凝土的运输距离作相应调整。 在一定程度上，混凝土强度随着搅拌时间的延长有所增长，但长时间搅拌既不经济也不合理，搅拌时间过长，不太坚硬的粗集料在大容量机中会因此脱角、破碎而影响混凝土质量。 (五)施工配合比的换算 在施工现场，拌和工应随时观察砂、石原材料的变化，随时测定砂、石的含水量，然后将试验室出具的理论配合比换算成施
10、工配合比，调整将要投入搅拌机的水、砂、石的质量。此项工作必须在保证水胶比不变的情况下进行。 (六)混凝土的养护 混凝土浇筑后，应及时进行养护。混凝土养护措施主要有喷雾养护、覆盖浇水养护。喷雾养护表面上空形成一层雾状隔热层，使表面混凝土在浇筑过程中减少阳光直射强度，降低表面环境温度，对减少混凝土在浇筑振捣过程中温度回升有较好效果；覆盖浇水养护，是以保护混凝土表面温度湿度为主。引起混凝土表面裂缝的原因是干缩和温度应力，干缩引起表面裂缝一般仅数厘米深度，主要靠养护解决。引起表面拉应力的温度因素有：气温变化、水化热和初始温差。气温变化主要有：气温骤降、气温年变化和日变化，特别是混凝土浇筑初期内部温度较
11、高时尤应注意表面保护。在混凝土表面覆盖塑料薄膜或湿麻包袋等，紧贴混凝土表面起到隔温效果，是防止表面裂缝的最有效措施。 四、工程应用 多年来，我们在来宾电厂、柳州电厂、桂林电厂、柳州回龙冲泵站、柳州堤防工程、合山电厂、田东电厂等民用建筑工程建设中，由于混凝土方量大，一直采用泵送混凝土的施工方法。我们不断更新和完善了泵送混凝土的施工工艺，加强对原材料的进场、搅拌过程控制、浇筑后的养护等各个细节的监督管理，从而提高了泵送混凝土生产质量，所生产的混凝土浇筑顺利，混凝土拌和物的和易性好、可泵性强，混凝土成品表面平整美观、光滑、密实。柳州回龙冲泵站、合山电厂等现场抽取的混凝土试块抗压强度和钻芯取样检测的结
12、果均满足设计要求，为创造优质工程提供了保证。 五、结论 第一，混凝土生产质量控制的关键在于原材料与拌和过程中各个细节的监督控制。施工过程中必须注意现场原材料的检测，同时分析和控制各因素、各环节，并有相关记录。 第二，认真贯彻质量目标，认真按照有关规范对混凝土生产质量严格控制，是获得优良泵送混凝土的保证。 参考文献 1GJ55-2000普通混凝土配合比设计规程S. 2廉慧珍，李玉琳关于混凝土配合比选择方法的讨论J.混凝土,2009，(5).organization system and working mode, the selection of a number of municipal st
13、rengthening group to build innovation and strengthen the organization of the basic level organizations advanced model.(seven) the manual work of the Communist Youth League Organization published and League branch of manual work, to promote the use of two manuals in the citys organizations at various
14、 levels. The county committee, directly under the group (work) is under the jurisdiction of grassroots League and group (total) using branch ratio shall not be less than 70%.Three, to further strengthen the groups leadership and team building(a) to strengthen the leagues leadership at all levels of
15、construction. Continue to do a good job of municipal Party Committee Organization Department on the strengthening of the Communist Youth League cadres management opinions implementation. To promote the group counties (autonomous counties, cities) Commission and city directly under the group (workers
16、) appointed to carry out the Five team building activities. Improve the League Association Department working mechanism. Conscientiously fulfill the duties of CO, combined with the city group directly under (the) Committee of the general election and the adjustment, actively jointly with the unit wh
17、ere the party organization department good group leadership selection with the work. Do a good job in municipal Party committee assistant committee leadership and leading cadres of the annual assessment work, adhere to and improve the assistant secretary of the Communist Youth League talk system gro
18、up To weave individual conversation and collective conversation, to strengthen the committees of all levels, the Standing Committee of the Standing Committee, the establishment of a sound system of central group learning, the system of investigation and study, the system of important issues and the
19、reporting system.(two) to strengthen the work of education and training of cadres to conscientiously implement the Central Committee. On the implementation of grassroots cadres training project and opinions on carrying out the mission municipal CYL Cadres training project implementation opinions, fu
20、ll implementation of the project of the City Youth League cadres training education. Focus on the county grassroots cadres and workers focused on training, the new school system vocational training League cadres, for the Municipal Organization Department jointly held the third session of the Communi
21、st Youth League system training cadres in party. Focusing on the construction of new socialist countryside, strengthening village cadres and rural construction team group member of the young team, the county organizations at various levels throughout the year is expected to train 100 00 rural grassr
22、oots cadres, plans to train 1000 village secretary of the village Party branch.(three) actively promote grassroots cadres election work. Under the unified leadership of the party organization, to strengthen grassroots organizations direct work, standardize the election work rules and procedures, in
23、the designated candidate, open competition to democratically elected branch secretary at the same time, actively and steadily the development of Township, streets and other grassroots organizations in the direct election of the pilot work, on the basis of summarizing the experience and gradually exp
24、and the scope of the pilot, and gradually formed a set of measures and cadres election system.(four) to strengthen the cadres testing exercise. To study the development of XX city from 2006 to 2008 cadres testing exercise planning. To select outstanding cadres to the central mission in Beijing, Shan
25、ghai, Guangzhou and other central organs and sending work in developed areas. With the Central Committee the implementation of the western region and ethnic minorities cadres training plan . To carry out the eighth batch of municipal organs attachment cadre management, selection, training work. The
26、outstanding cadres to start the National Development Bank XX branch testing exercise.(five) to strengthen the group construction. The main position to play the role of Youth League cadre education and training as the city, in accordance with the requirements of post training, further curriculum scie
27、ntifically and rationally, adopt arrangement menu course, basic theory includes group work, focus, hot and difficult issues, to enhance the content and practice; to strengthen the construction of teaching staff, the integration of teachers, establish a quality teacher training team, establish and im
28、plement course evaluation system; take delivery of training to the countryside, on-site training, and increase the rural grassroots cadres training efforts.Four, efforts to strengthen the work of young talent(a) to tenth XX young 54 medal in recognition of the publicity, and actively explore the XX
29、youth service. 54 Medal of institutionalization, standardization and socialization mechanism. Give full play to the XX award in recognition of 54 youth medal Association, Youth Award winner in the 54 chapter, investigation activities. Who won the Youth Service medal, dedication to the society to cre
30、ate conditions, build the stage. During the 54, named in recognition of the tenth XX young 54 medal. The association of XX editing of young talent , the exchange of information and communication platform for the XX of outstanding young talents.(two) the establishment of municipal Party committee of
31、young talent information database. In accordance with the feasible, effective, classification management, implement step by step principle, the establishment of municipal Party committee of youth talent database; guiding organizations at various levels generally established the young talent database
32、, construction of city, county (directly under the Communist Youth League), grassroots organizations three young talent information database the relevant information collection system, and gradually establish the citys young people, the Communist Youth League youth talent information network, provid
33、e information platform for young talent resource development.Five, take effective measures to strengthen the mission management(a) to strengthen the mission management work. Strengthen the dues collection and management, continue to adhere to the dues collection regularly reporting system, the annua
34、l comprehensive award in recognition of the tour and the tour one vote veto system audit system. Do statistical work in the group. The group service award in recognition of the advanced units, standardization, promoting group management work institutionalized.(two) to strengthen the organization of
35、research and information exchange efforts. Grassroots carry out research, efforts to form a number of theoretical results. Make full use of the network carrier, to explore the establishment of electronic group service system, promote the work of Communist Youth League information.Attachment 4:XX mun
36、icipal Party Committee Propaganda Department of the Communist Youth League work pointsIn 2006, the Communist Youth League propaganda ideological work XX to Deng Xiaoping theory and the important thought of Three Represents as guidance, study and implement the partys sixteen and the spirit of the the
37、 fifth Plenary Session of the 16th CPC Central Committee implementation of the eight plenary session of the two committee, the citys cultural work conference, the Propaganda Department of the meeting and the the fourth Plenary Session of the 15th CPC Central Committee permanent mission spirit, close
38、ly around 11th Five-Year XX the goal of full implementation of Scientific Outlook on Development, emancipating the mind, seeking truth from facts, keep pace with the times, close to reality, close to life, close to the young, persevere grasp orientation, grasping deepening, grasping construction inn
39、ovation, further improve the groups propaganda and ideological work ability, unity To guide the majority of members of the youth to achieve the 11th Five-Year planning tasks, the overall construction of a well-off society, building a socialist harmonious society to make new contributions.One, adhere
40、 to the Three Represents important thought and Scientific Outlook on Development education to guide the youth, to further strengthen the ideological and political education of youth(a) armed with youth science theory. Unremittingly with Deng Xiaoping theory and the important thought of Three Represe
41、nts armed members of youth education, to promote the study and implement to expand the depth and breadth. To study and implement the important thought of Three Represents with the establishment and implementation of Scientific Outlook on Development combine with the implementation of the requirement
42、s of constructing socialist harmonious society with Scientific Outlook on Development, carry out education as an important part of the theory of armed youth in the new period, strengthen the establishment and implementation of Scientific Outlook on Development education, educate and guide the youth
43、to fully understand the great significance of establishment and implementation of Scientific Outlook on Development, in-depth understanding of the Scientific Outlook on Development era back The king, the practice foundation, basic connotation, historical status, spirit and practice requirements, a p
44、rofound understanding of Scientific Outlook on Development with Marxism Leninism, Mao Zedong thought, inheriting and developing relationship between Deng Xiaoping theory and the important thought of Three Represents, to help young people establish and consciously practice Scientific Outlook on Devel
45、opment. Persist in learning, grasping the backbone, grasp the practice, grasp the opportunity. Catch club, effective way to grasp the network, with the group of cadres, young students and young backbone fronts as the focus, to promote the work of the armed youth theory to develop in depth, to help t
46、he youth continue to firm ideals and beliefs, to build a powerful spiritual pillar. To carry out the study and implementation of the partys sixteen session of the five Eight plenary session of the two plenary session of the Central Committee and the party spirit, to the citys Youth League members th
47、inking into the spirit of the meeting, to achieve the goal of national consciousness and XX economic and social development in 11th Five-Year period. Contribute to help and guide the youth to a profound understanding of the significance and main task of building a socialist harmonious society, actively join the construction of socialist harmonious society.(two) to strengthen the ideological and moral construction of teenagers. Thoroughly implement the central spirit of the document No. 8, No. 16 and the program for Improving Civic Morality to minors and students as focus groups, to s