姜 骞,于 诚
姜骞,于诚.水下隧道工程清水混凝土外观砂斑的成因分析[J].混凝土与水泥制品,2021(3):20-23,27.
JIANG Q,YU C.Causes Analysis for Sand Spots on Fair-faced Concrete for Side Wall in Underwater Tunnel[J].CHINA CONCRETE AND CEMENT PRODUCTS,2021(3):20-23,27.
水下隧道工程清水混凝土外观砂斑的成因分析
姜 骞,于 诚
姜骞,于诚.水下隧道工程清水混凝土外观砂斑的成因分析[J].混凝土与水泥制品,2021(3):20-23,27.
JIANG Q,YU C.Causes Analysis for Sand Spots on Fair-faced Concrete for Side Wall in Underwater Tunnel[J].CHINA CONCRETE AND CEMENT PRODUCTS,2021(3):20-23,27.
摘 要:为了研究清水混凝土外观砂斑的形成原因,对某水下隧道工程敞开段侧墙清水混凝土进行了质量调研与试验分析。结果表明:砂斑主要与混凝土用水量增加有关;原材料中粉煤灰品质的波动增加了混凝土用水量;为了在相同减水剂掺量下满足混凝土拌合物的流动性要求,大幅增加用水量造成混凝土中自由水过多,析出带走混凝土表面的胶凝材料颗粒,由此导致砂斑缺陷;针对缺陷的成因,从原材料品质控制、拌合生产、浇筑施工和及时养护等角度,提出了提升清水混凝土外观质量的建议。
Abstract: Aiming at a better understanding of cause of sand spots formation on fair-faced concrete for side wall in open section of some underwater tunnel, concrete construction quality on-site and experimental research within-laboratory were conducted. The results show that the concrete defect is found to be related to overuse of mixing water. To fulfill the workability of fresh concrete with same dosage of water reducer, water demand of concrete mixtures is increased for quality variation of fly ash. The excessive quantities of mixing water in the system lead to too much free water in paste. Binder particles on the surface of concrete are flushed away, and the sand spots appear. In addition, considering the cause of the defect, concrete surface quality promotion advices, including control of raw materials quality, pouring construction, and immediately curing, are put forward.
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