Blending amount
一般来说 5-10% 胶凝材料的用量.
The mixing method of silica fume is divided into internal mixing 和 external mixing.
- 内部混合: under the premise of the same amount of water, 1 部分硅粉可替代 3-5 水泥零件 (重量) 并在保持混凝土抗压强度不变的同时提高混凝土的其他性能.
- External mixing: the amount of cement remains unchanged, and the addition of silica fume significantly improves the strength of concrete and other properties. 掺有硅粉的混凝土有一定坍落度损失时. 比例测试中需要注意这一点.
Silica fume must be used in conjunction with water reducing agents, it is recommended to compound fly ash and finely ground slag to improve its constructability.
When formulating concrete with silica fume, the general weight ratio with cementitious materials is:
- 高性能混凝土: 5-10%.
- 水工混凝土: 5-10%
- 喷射混凝土: 5-10%.
- 泵送助剂: 2-3%.
- wear-resistant industrial flooring: 6-8%.
- 聚合物砂浆, 保温砂浆: 10-15%.
- Indefinite refractory castables: 6-8%. Before use, please select the reasonable and economic mixing amount through experiment according to the actual needs.
Mixing method.
Silica fume concrete and castables should be made by the test room. Strictly follow the construction ratio. Silica fume should be added to the mixer immediately after the aggregates are fed. There are two procedures for adding.
- Into the aggregate, 其次是硅粉, 水泥干混料, and then add water and other admixtures.
- 放入粗骨料 + 75% 水 + 微硅粉 + 50% 细骨料, mix for 15-30 秒, 然后放入水泥 + 混合物 + 50% 细骨料 + 25% 水, mix until uniform. 混合时间为 20-25% 或者 50-60 比普通混凝土长几秒. Never add silica powder into the already mixed concrete.
Construction method
There is no significant difference between the construction method of silica fume concrete and ordinary concrete, but it is necessary to organize and vibrate densely during construction well. The early strength of silica fume concrete will make the final setting time earlier, which should be paid attention to when plastering; 同时, the addition of silica fume will improve the viscosity of concrete and significantly reduce water secretion, making plastering slightly difficult.
Construction safety
Silica fume concrete construction safety should be strictly in accordance with the relevant national construction specifications for concrete projects, but because silica fume is light, it is strictly prohibited to throw the material from a height to prevent silica fume from flying.
