浅谈混凝土现浇楼板裂缝的控制及处理.doc

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1、【精品文档】如有侵权，请联系网站删除，仅供学习与交流浅谈混凝土现浇楼板裂缝的控制及处理.精品文档.浅谈混凝土现浇楼板裂缝的控制及处理【论文关键词】:现浇楼板；裂缝；控制；处理【论文摘要】:在建筑施工中，现场浇注的混凝土楼板常常会出现大小不等，深浅不一的裂缝现象，文章通过分析现浇混凝土楼板常见裂缝的表现状况，揭示了裂缝产生的原因，并且提出了如何控制预防和处理的根本性措施。钢筋混凝土的裂缝控制问题是建筑工程中很重要的问题之一，现浇混凝土楼板裂缝是公认的建筑施工中最难解决的问题之一，这些裂缝不仅影响建筑物的美观，而且影响建筑物的使用功能，大大降低了房屋结构的耐久性；破坏结构的整体性、降低其刚度；引起

2、钢筋腐蚀。因此如何解决这种常见的混凝土裂缝，是设计者和施工者都不可忽视的问题。一、裂缝表现斜向裂缝：多分布在房屋外墙转角所在房间的楼板上，裂缝一般成45o斜向，有时一只角同时出现两条裂缝，裂缝基本上为上下贯通。如某七层框架商住楼工程，结构总长度约为100m，设有两道温度缝，其基础一侧为条形基础，其余为独立承台基础。在工程交接时后两个月左右突然发现在靠其中一条温度缝的一跨柱角楼板有45。裂缝，从三层至六层楼板每层均有3条，但均未贯穿楼板。纵横向裂缝：主要表现为纵横向裂缝。如某教学楼，其现浇钢筋混凝土楼板大面积出现宽度0.10.3mm不等的纵横向裂缝。表面龟裂:此类裂缝主要表现在施工过程中产生的裂

3、缝，容易控制与处理。如某在建工程，因板面面积大，在晚上浇混凝土，第二天早上派人浇水，但前面浇，后面就干掉，到中午时板面出现龟裂缝，用肉眼可辩识。二、混凝土楼板裂缝产生的原因1.混凝土组成材料的影响(1)水泥方面的影响：水泥的收缩值般取决于C3A、SO3、石膏的含量及水泥细度等。即C3A含量大，细度较细的水泥收缩较大。石膏含量不足的水泥，具有较大的收缩，而SO3的含量对混凝土收缩的影响显著。(2)骨料方面的影响：混凝土收缩随骨料含量的增加而减小，随骨料弹性模量的增加而减小，同时，又随骨料中粘土含量的增加而增大。另外，在预拌混凝土中，其骨料的级配不十分合理也是造成混凝土出现裂缝的主要因素。(3)混

4、凝土配合比方面的影响：包括单位用水量，单位水泥用量，水灰比，砂率及灰浆比等参数。混凝土收缩主要取决于单位用水量和水泥用量，而用水量的影响比水泥用量大；在用水量一定的条件下，混凝土干缩随水泥用量的增大而增加，但增大的幅度较小；在骨灰比一定条件下，混凝土干缩随水灰比的增加而明显增大；在配合比相同条件下，混凝土干缩随砂率的增大而加大，但增大的幅度较小。(4)外加剂的种类和掺量方面的影响：掺用化学外加剂会使混凝土收缩有不同程度的增大。掺减水剂用于改善混凝土和易性，增大坍落度时，掺减水剂的混凝土收缩略大于不掺的收缩值；掺减水剂用于减水，提高强度或节约水泥时，掺减水剂混凝土的收缩接近或小于不掺的收缩值。2

5、.施工方面的原因(1)水灰比的变化对混凝上强度值的影响十分明显，基本上分别是水和水泥量变动对强度影响的叠加，故此，水、水泥、外加剂的计量变化，将直接影响混凝土的强度。对于大流动性的混凝土，其塑性收缩值为200×l0-4，中等流动性混凝土，其塑性收缩值约为(60100)×l0-4。表现较明显的是：满足坍落度大、流动性好的泵送条件的泵送混凝土，较易产生粗骨料少、砂浆多的现象，混凝土脱水凝固时，就会较易产生塑性收缩裂缝。(2)混凝土是由砂、石、水泥等粗细骨料按一定的配合比，经过水化反应而形成的水硬性胶凝材料，如果混凝土材料中的砂、石颗粒级配不好，则浇灌出的混凝土强度将降低，抵抗外

6、界应力的能力也同时减弱，极易造成混凝土裂缝。(3)施工过程中过分振捣混凝土后，粗骨料沉落，水、空气被挤出，混凝土表面因泌水而形成竖向体积缩小沉落，从而成表面砂浆层，它比下层混凝土有较大的干缩性能，待水分蒸发后，容易形成塑性收缩裂缝。(4)模板、垫层在浇筑混凝土前淋水不足，过分干燥，浇筑混凝土后，因模板吸水量大，导致混凝土的收缩，产生塑性收缩裂缝。(5)工程施工中各工种交叉作业，楼面负筋位置的正确性难以得到有效的保证，经踩踏后将令钢筋弯曲、变形，减低了部分板负筋的有效高度，使该位置钢筋混凝土楼板上部抗拉能力大幅降低，从而导致该部混凝土楼板出现裂缝。(6)浇筑混凝土后过分抹平压光，会使较多的细骨料

7、浮到混凝土表面，形成含水量很大的水泥浆层。空气中的二氧化碳与水泥浆中的氢氧化钙发生作用生成碳酸钙，其化学反应式为CO2+Ca(OH)2=CaCO3+H20，于是浇筑硬化后期(56d后)引起混凝土明显收缩，即碳化收缩，导致混凝土楼板出现裂缝。(7)混凝土的保湿养护对其强度增长和各类性能的提高十分重要，特别是早期的妥善养护可以避免表面脱水，并大量减少混凝土初期收缩裂缝的产生。过早的养护会影响混凝土的胶结能力；而过迟的养护，混凝土会因受日晒风吹令其表面游离水分过快蒸发，水泥由于缺乏必要的水化水，从而产生急剧的体积收缩(据有关资料反映，当混凝土表面的水分蒸发率超过0.5kgm2*h时，混凝土体积将急剧

8、收缩)，此时的混凝土早期强度低，未能抵抗该种收缩应力而产生开裂。特别是在夏、冬两季，因昼夜温差较大，养护不当最容易产生温差裂缝。三、混凝土裂缝的控制措施(1)优选水泥品种。混凝土结构引起裂缝的主要原因之一是由于水泥水化热的大量积聚致使混凝土出现早期升温及后期降温而产生的温差变化，为此，在施工中可采取一些措施，如选用矿渣水泥、粉煤灰水泥等低热水泥品种来配制混凝土。(2)控制材料的使用。根据施工的具体条件降低水灰比，减少水的用量，提高混凝土的密实度，可以减少混凝土的泌水、离析等现象，使混凝土的收缩变形减小。施工时尽可能选用良好的颗粒级配方案，用颗粒级配大的粗中砂来拌制混凝土，严格控制砂、石中的含泥

9、量。另外，还应控制施工工期，尽量不要在高温季节施工，可减少温差应力对混凝土变形的影响。(3)提高操作水平。加强混凝土振捣，可以提高混凝土的密实性和抗拉强度；加强对混凝土成品的保护和养护，避免温差裂缝的产生；对已浇筑好的混凝土应在浇筑后lO到12小时内及时做好浇水养护，以使混凝土有足够的湿度保持水化反应，并且连续养护日期一般不少于半个月。这样，不仅有利于混凝土在规定龄期内达到设计要求的强度，而且还可以在养护时降低混凝土的表面温度，减少混凝土内部的约束作用，防止收缩裂缝的产生。(4)控制钢筋位置。在绑扎构造钢筋时为防止钢筋走位，可以用一些技术措施进行控制，从而有效地控制和减少板面裂缝的发生。四、混

10、凝土裂缝处理依据混凝土裂缝宽度，深度以及扩展情况，采取不同的处理方法。(一)对于浅表面裂缝(沉缩裂缝，干缩裂缝)，缝宽小于0.5m，可用下列方法：1.裂缝表面清理干净，用水泥浆刮抹。2.稍深一些的裂缝，沿裂缝凿去薄弱部分，用水冲洗后，用1：2水泥砂浆修补。(二)裂缝较深(10mm以上)1.注射环氧树脂黏合剂。注射前，用电吹风吹干裂缝，然后用注射器把黏合剂缓慢注入，至全部充满。2.裂缝口扩成v型，用毛刷清除粉末，用电吹风吹干，在扩口内填入环氧树脂胶泥即可。结束语综上所述，现浇楼板的裂缝问题并不是一个无法跨越的难题，只要我们严格把好材料进场关，系统控制施工工艺，严格操作程序，现浇混凝土楼板的裂缝问

11、题可以得到有效解决，为社会的安全稳定作出更大的贡献，为企业自身创造出更好的经济效益。（英文版 ） Two regulations promulgated for implementation is in the party in power for a long time and the rule of law conditions, the implementation of comprehensive strictly strategic plan, implementation in accordance with the rules and discipline to manage t

12、he party, strengthen inner-party supervision of major initiatives. The two regulations supporting each other, the adhere to a positive advocate, focusing on morality is of Party members and Party leading cadres can see, enough to get a high standard; around the party discipline, disciplinary ruler r

13、equirements, listed as negative list, focusing on vertical gauge, draw the party organizations and Party members do not touch the bottom line . Here, the main from four square face two party rules of interpretation: the first part introduces two party Revised regulations the necessity and the revisi

14、on process; the second part is the interpretation of the two fundamental principles of the revision of laws and regulations in the party; the third part introduces two party regulations modified the main changes and needs to grasp several key problems; the fourth part on how to grasp the implementat

15、ion of the two regulations of the party. and revised the necessity and revised history of the CPC Central Committee the amendment to the Chinese Communist Party members and leading cadres honest politics several guidelines and column 1 by 2015 to strengthen party laws and regulations focus. Two part

16、y regulations revision work lasted a Years, pooling the wisdom of the whole party, ideological consensus, draw historical experience, respect for the wisdom of our predecessors, which reflects the unity of inheritance and innovation; follow the correct direction, grasp the limited goals, adhere to t

17、he partys leadership, to solve the masses of the people reflect a focus on the problem. The new revision of the and , reflects the partys 18 and the eighth session of the third, the spirit of the fourth plenary session, reflecting the experience of studying and implementing the General Secretary Xi

18、Jinping series of important speech, reflects the partys eighteen years comprehensive strictly practice. (a) revised two regulations of the party need of in based on revised, the promulgation and implementation of January 2010, to strengthen the construction of the contingent of leading cadres play a

19、n important role. But with the party to manage the party strictly administering the deepening, has not been able to fully meet the actual needs. Content is too complicated, eight prohibition, 52 are not allowed to hard to remember, and also difficult to put into practice; the second is concisely pos

20、itive advocated by the lack of prohibited provisions excessive, no autonomy requirements; the third is banned terms and discipline law, both with the party discipline, disciplinary regulations repeat and Criminal law and other laws and regulations repeat; the fourth is to clean the theme is not prom

21、inent, not for the existing problems, and is narrow, only needle of county-level leading cadres above. is in 1997 based on revision, in December 2003 the promulgation and implementation, to strengthen the construction of the party play very important role. Along with the development of the situation

22、, which many provisions have been unable to fully meet the comprehensive strictly administering the practice needs. One is Ji law, more than half of the provisions and criminal law and other countries laws and regulations Repetition; two is the political discipline regulations is not prominent, not

23、specific, for violation of the party constitution, damage the authority of Party Constitution of misconduct lack necessary and serious responsibility to pursue; third is the main discipline for the leading cadres, does not cover all Party members. Based on the above situation, need to and the two is

24、 likely to be more relevant regulations first amendment. By revising, really put the authority of Party discipline, the seriousness in the party tree and call up the majority of Party members and cadres of the party constitution of party compasses party consciousness. (II) two party regulations revi

25、sion process the Central Committee of the Communist Party of China attaches great importance to two regulations revision . Xi Jinping, general books recorded in the Fifth Plenary Session of the eighth session of the Central Commission for Discipline Inspection, on the revised regulations made clear

26、instructions. According to the central deployment, the Central Commission for Discipline Inspection from 2014 under six months begin study two regulations revision. The Standing Committee of the Central Commission for Discipline Inspection 4 review revised. Comrade Wang Qishan 14 times held a specia

27、l meeting to study two regulations revision, amendment clarifies the direction, major issues of principle, path and target, respectively held a forum will listen to part of the province (area) secretary of the Party committee, Secretary of the Discipline Inspection Commission, part of the central mi

28、nistries and state organs Department The first party committee is mainly responsible for people, views of experts and scholars and grassroots party organizations and Party members. Approved by the Central Committee of the Communist Party of China, on 7 September 2015, the general office of the Centr

29、al Committee of the Party issued a notice to solicit the provinces (autonomous regions, municipalities) Party, the central ministries and commissions, state ministries and commissions of the Party (party), the General Political Department of the military, every 3 people organization of Party of two

30、regulations revision opinion. Central Commission for Discipline Inspection of extensive solicitation of opinions, careful study, attracting, formed a revised sent reviewers. In October 8 and October 12, Central Committee Political Bureau Standing Committee and the Political Bureau of the Central Com

31、mittee After consideration of the two regulations revised draft. On October 18, the Central Committee of the Communist Party of China formally issued two regulations. Can say, two laws amendment concentrated the wisdom of the whole party, embodies the party. Second, and revision of the basic princip

32、les of two party regulations revision work and implement the partys eighteen, ten eight plenary, the spirit of the Fourth Plenary Session of the Eleventh Central Committee and General Secretary Xi Jinping important instructions on the revised and , highlighting the ruling party characteristics, seri

33、ous discipline, the discipline quite in front of the law, based on the current, a long-term, advance as a whole, with Bu Xiuding independent and . Main principle is: first, adhere to the party constitution to follow. The constitution about discipline and self-discipline required specific, awaken the

34、 party constitution of party compasses party consciousness, maintaining the authority of the constitution. General Secretary Xi Jinping pointed out that no rules, no side round. Party constitution is the fundamental law, the party must follow the general rules. In early 2015 held the eighth session

35、of the Central Commission for Discipline Inspection Fifth Plenary Session of the 16th Central Committee, Xi Jinping again pointed out that constitution is the party must follow the general rules, but also the general rules. the revision of the and is Method in adhere to the regulations established f

36、or the purpose of combining rule of virtue is to adhere to the party constitution as a fundamental to follow, the constitution authority set up, wake up the party constitution and party rules the sense of discipline, the party constitution about discipline and self-discipline specific requirements.

37、4 second is to adhere to in accordance with the regulations governing the party and the party. The Party of rule of virtue de, mainly refers to the partys ideals and beliefs, excellent traditional style. The revised the closely linked to the self-discipline, insisting on the positive initiative, for

38、 all members, highlight the vital few, emphasized self-discipline, focusing on the morality, and the majority of Party members and the ideological and moral standards. The revised Ji method separately, Ji, Ji Yan to Method, as a negative list, emphasizing the heteronomy, focusing on vertical gauge.

39、Is this one high and one low, a positive reaction, the strict party discipline and practice results transformation for the integration of the whole party to observe moral and discipline requirements, for the majority of Party members and cadres provides benchmarking and ruler. Third, insist on to. I

40、n view of the problems existing in the party at the present stage, the main problems of Party members and cadres in the aspect of self-discipline and abide by the discipline to make clearly defined, especially the partys eighteen years strict political discipline and political rules, organization an

41、d discipline and to implement the central eight provisions of the spirit against the four winds and other requirements into Disciplinary provisions. Not one pace reachs the designated position, focusing on in line with reality, pragmatic and effective. After the revision of major changes, major chan

42、ges in the and modified and needs to grasp several key problems (a) adhere to according to regulations governing the party and party with morals in combination, for at the present stage, the leadership of the party members and cadres and Party members in existing main problems of self-discipline, pu

43、t forward principles, requirements and specifications, showing Communists noble moral pursuit, reflected at all times and in all over the world ethics from high from low 5 common requirements. One is closely linked to the self-discipline, removal and no direct relation to the provisions of . the sec

44、ond is adhere to a positive advocate, eight prohibition 52 are not allowed to about the content of the negative list moved into synchronization amendment . Three is for all the party members, will apply object from the leadership of the party members and cadres to expand to all Party members, fully

45、embodies the comprehensive strictly required. The fourth is prominent key minority, seize the leadership of the party members and cadres is the key, and put forward higher requirements than the ordinary Party members. Five is to simplify, and strive to achieve concise, easy to understand, easy to re

46、member. The revised is the ruling Party since the first insists on a positive advocate forAll Party members and the self-discipline norms, moral declaration issued to all members of the party and the National Peoples solemn commitment. criterion of a clean and honest administration consists of 4 par

47、ts, 18, more than 3600 words. After the revision of the , a total of eight, 281 words, including lead, specification and Party member cadre clean fingered self-discipline norms, etc. Part 3 members low-cost clean and self-discipline, the main contents can be summarized as four must eight code. Lead part, reiterated on ideal and faith, fundamental purpose, the fine traditions and work style, noble sentiments, such as four must the principle of requirements, strong tone of self-disc