1. Laitance and control measures

自密實混凝土澆筑完畢后，表面容易出現較多浮漿。為避免過多浮漿的出現，應在澆筑過程中，根據不同部位，控制其相應的擴展度。如本梁場小箱梁澆筑，在澆筑底板時，混凝土的坍落擴展度控制在690mm～710mm；當澆筑頂板時，混凝土坍落擴展度控制在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

自密實混凝土和易性不穩定，混凝土在澆筑時，和易性不良，易出現分散、離析及“假凝”現象。在混凝土拌和前，需嚴格控制檢測骨料的含水率、粉料的入機溫度及運輸過程中對攪拌運輸車防曬措施及運輸時間的控制。

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

自密實混凝土在澆筑時，常因擴展度偏大或者偏小造成施工困難，進而導致結構物出現實體質量問題。其主要原因是骨料中所含的水分，尤其陰雨天氣因素，及潮濕環境因素，使骨料中所含水分發生較大變化。所以需對混凝土的骨料含水率通過“多檢多測”的方式來控制骨料中所含水分，以保證混凝土使用時具有良好的坍落擴展度，方便施工，進而保證施工成型質量。

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.