1. Laitance and control measures

自密实混凝土浇筑完毕后，表面容易出现较多浮浆。为避免过多浮浆的出现，应在浇筑过程中，根据不同部位，控制其相应的扩展度。如本梁场小箱梁浇筑，在浇筑底板时，混凝土的坍落扩展度控制在690mm～710mm；当浇筑顶板时，混凝土坍落扩展度控制在670mm～690mm。

After the self compacting concrete is poured, more laitance is easy to appear on the surface. In order to avoid the appearance of excessive laitance, the corresponding expansion degree should be controlled according to different parts in the pouring process. If the small box girder is poured in the beam yard, the slump expansion of concrete is controlled between 690mm and 710mm when pouring the bottom slab; When pouring the roof, the slump expansion of concrete should be controlled between 670 mm and 690 mm.

2和易性及控制措施

2. Workability and control measures

自密实混凝土和易性不稳定，混凝土在浇筑时，和易性不良，易出现分散、离析及“假凝”现象。在混凝土拌和前，需严格控制检测骨料的含水率、粉料的入机温度及运输过程中对搅拌运输车防晒措施及运输时间的控制。

The workability of self compacting concrete is not stable. When pouring, the workability of concrete is poor, and it is easy to appear dispersion, segregation and "false setting" phenomenon. Before concrete mixing, it is necessary to strictly control the moisture content of the tested aggregate, the temperature of the powder into the machine, and the control of the sun protection measures and transportation time of the mixing truck during the transportation.

3骨料含水率及控制措施

3. Aggregate moisture content and control measures

自密实混凝土在浇筑时，常因扩展度偏大或者偏小造成施工困难，进而导致结构物出现实体质量问题。其主要原因是骨料中所含的水分，尤其阴雨天气因素，及潮湿环境因素，使骨料中所含水分发生较大变化。所以需对混凝土的骨料含水率通过“多检多测”的方式来控制骨料中所含水分，以保证混凝土使用时具有良好的坍落扩展度，方便施工，进而保证施工成型质量。

When self compacting concrete is poured, it is often difficult to construct due to the large or small expansion, which leads to the solid quality problems of the structure. The main reason is that the moisture content in aggregate, especially in rainy weather and humid environment, changes greatly. Therefore, it is necessary to control the moisture content of aggregate through "multi inspection and multi measurement" method, so as to ensure that the concrete has good slump expansion, facilitate the construction, and ensure the quality of construction molding.