探讨施工振捣不密实导致混凝土渗水问题.doc

http:/www.taxmbz.com http:/www.tscsqs.com http:/www.xintainz.com http:/www.fangshuidian.com 探讨施工振捣不密实导致混凝土渗水问题引起裂缝有两大类原因，一种由外荷载（如静、动荷载）的直接应力和结构次应力引起的裂缝；一种是混凝土渗水的原因是由于混凝土内部孔隙形成连通的渗水孔道。这些孔道主要来源于水泥浆中多余的水分蒸发而留下的气孔、水泥浆泌水所产生的毛细管孔道、内部的微裂以及施工振捣不密实产生的蜂窝、孔洞，这些都会。Is the cause of seepage water of concrete due to inside the concrete pore formed connected water seepage channel. Excess water in the channel mainly comes from the slurry evaporation hole left by the parities, the slurry water generated by the vibrating capillary channel, internal micro cracks and construction not dense honeycomb, holes, these will cause water seepage of concrete. 引起裂缝有两大类原因，一种由外荷载（如静、动荷载）的直接应力和结构次应力引起的裂缝；一种是结构因温度、膨胀、收缩、徐变和不均匀沉降等因素由变形变化引起的裂缝。Cause cracks has two kinds, a kind of by the outside load, such as static, dynamic loads caused by the direct stress and structural stress cracks; Is a kind of structure by temperature, expansion, shrinkage, creep and uneven settlement cracks caused by deformation of the change. 1.1 设计方面1.1 design aspects 选型：工艺、结构选型不当或实际运行与设计条件不符。Selection: technology, structure selection or improper operation does not accord with design conditions. 计算：结构分析计算简图不当，受力构件计算错误。Computing: improper structure calculation diagram, stress component calculation error. 沉降缝：水池的沉降缝或伸缩缝处理不当。Settlement joint and expansion joint of settlement joint: pool of improper handling. 图纸：套用图纸，使用不当。Using drawings, drawings: improper use. 1.2 材料缺陷1.2 material defects 从砼的性质来说影响因素大概有：干燥收缩、温差、塑性收缩、自干燥 、外加剂、徐变等。From the nature of the influence factors about: concrete, plastic shrinkage, drying shrinkage, temperature difference from dry, admixture, creep, etc. 1.3 施工管理1.3 construction management 地基处理：地基处理不符合设计要求。砼配合比：配合比设计是否合理，水泥与外加剂是否相适应，砂石级配及其含泥量是否符合规范要求，酱油砼坍落度控制是否合理，这些都影响到砼的质量及其收缩变形。(1) foundation treatment, foundation treatment is not in conformity with the design requirements. (2) the concrete mixture ratio, mixture ratio design whether reasonable, whether the cement and admixture, sand and gravel gradation and silt content conformed to the specification requirements, the concrete slump control is reasonable, all of these affect the quality, the shrinkage deformation of concrete. 浇筑震捣：砼浇筑震捣不均匀密实，施工缝和细部处理会带来结构开裂的后患；过震则使浮浆过厚，抹压又不及时，则砼表面出现塑性裂缝。(3) pouring vibrating: uneven vibrating compacted concrete casting, construction joint and structure that details can bring for cracking; Too thick shock makes the floating cement, plastering and not in time, the concrete surface of the plastic crack appeared. 拆摸板：边墙拆摸板过早（13d），砼水化热正处于高峰，内外温差最大。(4) open touch panel: sidewall touched down the board early (1 3 d), concrete hydration heat is in peak, the largest temperature difference between inside and outside. 养护：许多施工单位往往忽视砼养护这一环节，尤其是墙体和柱梁的保温保湿养护不到位，容易产生收缩裂缝。(5) maintenance: many construction units tend to ignore the concrete curing this link, especially the wall and column beam insulation moisture curing does not reach the designated position, prone to shrinkage crack. 管理：施工管理不严，赶进度，偷工减料，工人素质差，施工马虎等也是造成结构裂缝的人为因素。6 management, construction management is lax, catch up, to cut corners, workers' quality is poor, careless of construction and structure cracks caused by human factors. 1.4 维护管理1.4 maintenance and management 对维护缺乏认识。除荷载问题外，主要是环境温度和风速引起的收缩变形所致。钢筋砼结构与其他物件一样都存在"热胀冷缩"的特征，尤其复合土工膜超长结构更为明显，所以，应重视已浇结构的保温保湿维护工作。Lack of awareness to the maintenance. In addition to the load problem, mainly caused by shrinkage deformation due to ambient temperature and wind speed. Reinforced concrete structure and the other items are "heat bilges cold shrink" characteristics, especially super long structure is more obvious, therefore, should pay attention to have been watering the insulation structure of moisturizing maintenance work. 2 抗渗混凝土渗漏的预防措施2 impermeable concrete seepage prevention measures 2.1 设计因素2.1 design factors 设计中应充分考虑地下水作用的最不利情况，即地下水、地表水和毛细管水对结构的作用以及由于人为因素而引起的周围水文地质变化的影响。1) should be fully considered in the design of the most unfavorable situation of the groundwater, groundwater, surface water and capillary water and the function of structure caused by man-made factors and surrounding hydrological geological change. 结构设计中，应根据地下工程确定的几何尺寸，合理配置钢筋，使大体积混凝土具有足够的抗裂能力而不出现裂缝。(2) in the design, should according to the geometry size specified in the underground engineering, the reasonable configuration of reinforced, make with enough mass concrete crack resistance ability without cracks. 根据结构断面形状、荷载、埋深，基础的强度，采用结构自防水混凝土，即补偿收缩混凝土。(3) according to the structure of the cross section shape, load, buried depth, foundation strength, adopts the structure of the waterproof concrete and shrinkage compensating concrete. 以膨胀加强带取代后浇缝即在结构收缩应力最大的地方，产生相应较大的膨胀来补偿结构的收缩。(4) expansion reinforcing band instead of post-cast seam shrinkage stress in the structure's biggest place, produce the corresponding large expansion structure to compensate for shrinkage. 根据结构设计，合理设置后浇带和变形缝。5. According to the structure design, reasonable and setting post-cast strip deformation seam. 设计图中，应着重绘制加强带、后浇带、变形缝和施工缝等构造详图，便于施工。6 design drawing, the drawing should be paid to strengthen post-cast strip belt, detail, construction joint and deformation joint construction, convenient for construction. 2.2 施工因素2.2 the construction factors 当混凝土内外最大温差小于25时，混凝土就不会产生表面裂缝。因此要作好测温记录，以掌握实际温度场的变化。1) when the concrete is less than 25 , the maximum temperature difference inside and outside surface cracks in concrete are not produced. So to make a good record of temperature measurement, in order to grasp the actual changes in the temperature field. 抗渗混凝土用的水泥，宜优先选用强度等级为42.5级的矿渣硅酸盐水泥，但应注意延长搅拌时间。(2) the permeability of concrete with cement, appropriate is preferable strength slag Portland cement with a magnitude of 42.5 grade, but should be extended mixing time. 严格控制砂石含泥量，并通过精心级配，提高混凝土的抗拉强度。(3) strict control sand silt content, and through carefully graded, improve the tensile strength of concrete. 基础底板和围护墙可采用240370mm厚的砖模，混凝土浇筑后，砖模不拆即回填土。(4) foundation slab and the enclosure wall can use 240 370 mm thick brick mold, concrete pouring, brick die don't dismantle the backfill soil. 基础底板采用预应力混凝土，利用预应力筋张拉后的弹性回缩，消除结构裂缝。(5) foundation slab using prestressed concrete, prestress tendons tensioning after elastic retraction, eliminate structural cracks. 防水泥凝土必须使用同一品种水泥。6. Prevent cement must use the same varieties of cement concrete. 混凝土采用分层浇筑。7 different layers of the concrete pouring. 加强对商品混凝土现场监控力度专人检测混凝土的坍落度和搅拌时间。Today to strengthen commercial concrete on-site monitoring strength detection of concrete slump and mixing time. 防水混凝土及补偿收缩混凝土的养护，严重影响结构的抗渗性，特别是早期养护更为敏感。一般养护要注意：Pet-name ruby waterproof concrete and shrinkage compensating concrete curing, seriously affect the impermeability of structure, especially the early curing is more sensitive. General maintenance should pay attention to: a.防水混凝土和hea补偿收缩混凝土终凝后(浇筑后46h)，应立即覆盖双层草帘或麻袋养护。A. waterproof concrete and hea compensation shrinkage concrete after the final set (4 6 h after casting), should be covered immediately double hulls or sack of maintenance. b.不宜采用电热养护，容易产生温度裂缝，降低混凝土的抗渗性。B. unfavorable use electric heat curing, easy to produce temperature crack, reduce the permeability resistance of concrete. c.不宜采用蒸汽养护，导致混凝土结构抗渗性下降。C. should not be using steam curing, led to the decrease of the permeability resistance of concrete structure. d.防水混凝土不应过早拆模，避免混凝土表面裂缝。D. waterproof concrete should not be too early to open mold, avoid concrete surface cracks. e.冬期施工，防水泥凝土的原材料可采用预热法，混凝土的出机温度不宜大于35。E. winter construction, cement preheating method can be used raw materials of concrete, the concrete of the temperature of the machine should not be greater than 35 . f.防水混凝土冬期宜采用蓄热法养护。当采用暖棚养护法时，棚内应保持一定湿度，防止混凝土早期脱水。F. waterproof concrete winter appropriate USES heat storage method of curing. When greenhouses curing method is used, the relative should maintain a certain humidity, prevent concrete early dehydration.