结构混凝土刚性自防水局部失效的原因
Causes of local failure of structural concrete rigid self waterproofing
1)混凝土原材料难以严格控制造成混凝土性能缺失。
1) It is difficult to strictly control the raw materials of concrete, resulting in the lack of concrete performance.
第一，天然开采的砂石或人工破碎的砂石，都很难满足理想的级配要求，达不到理想抗渗的曲线。
First, it is difficult to meet the requirements of the ideal gradation for the naturally mined sand and gravel or the artificially crushed sand and gravel.
第二，砂、石、水泥、水的级配难以均匀 、准确。灰砂比偏大，砂子数量少，水泥量大，混凝土收缩大而产生裂缝。反之砂子多，水泥少，水泥不能全部包裹砂子，拌合干涩，缺乏粘结力，混凝土密实度不够。
Second, the gradation of sand, stone, cement and water is difficult to be uniform and accurate. The cement sand ratio is too large, the amount of sand is less, the amount of cement is large, and the shrinkage of concrete is large. On the contrary, more sand, less cement, cement can not all wrap sand, dry mixing, lack of cohesive force, concrete compactness is not enough.
第三，砂、石含泥量往往过大，超过要求的2%。
Third, the mud content of sand and stone is often too large, exceeding the required 2%.
第四，对掺加外加剂的认识不当，适量加入减水剂很有效果，但往往热衷于膨胀剂。膨胀剂先期有效，后期裂缝增多。
Fourth, the understanding of admixtures is not proper. It is effective to add appropriate amount of superplasticizer, but it is often keen on expansive agent. The expansion agent is effective in the early stage and cracks increase in the later stage.
2)结构混凝土的局部施工浇筑质量缺陷造成原因。
2) The reasons for the quality defects of local construction pouring of structural concrete.
a、由于混凝土结构不严密产生的通道，包括浇筑中混凝土振捣不实或施工过程出现暂停、与旧混凝土接磋不是按施工缝作业，形成带状混凝土局部松散。
a. Due to the concrete structure is not tight, including the concrete vibration is not solid or the construction process is suspended, and the connection with the old concrete is not according to the construction joint operation, forming the belt concrete partial loose.
b、模板支设不严密产生缝隙漏浆形成的局部混凝土不密实。
b. If the formwork is not set up tightly, the local concrete caused by gap leakage is not dense.
c、通过地下室自防水砼的支撑铁件或预埋件没有严格实施防止漏水措施(不加焊止水环等)引起的预埋件与混凝土之间的裂缝。
c. Through the basement self waterproof concrete supporting iron or embedded parts are not strictly implemented to prevent water leakage measures (without welding water stop ring, etc.) caused by cracks between embedded parts and concrete.