In the process of dosing and mixing of Ewende micro silica powder (silica fume), the following matters need to be paid attention to:
- Choosing the appropriate dosing method: Usually the concrete industry uses densified micro silica powder, and can choose manual dosing or automatic dosing.
- Timing of adding: Due to the unique superfine characteristics of micro silica powder, it should be put into micro silica powder immediately after aggregate feeding, and the powdered micro silica powder should not be added into the concrete that has already been mixed properly.
- Mixing time: The mixing time of concrete mixed with micro silica powder is longer than that of ordinary concrete. Generally speaking, the mixing time should be 0.5 times longer than that of ordinary concrete, 20-25% longer or 50-60 seconds longer, the specific time is subject to obtaining good uniformity.
- Matching ratio: Micro silica powder concrete and casting material should be made by the laboratory to make the construction matching ratio, and the construction should be strictly according to the matching ratio.
- Joining method: There are two procedures for joining micro silica powder. First, put into the aggregate, then put into the micro silica powder, cement dry mix, and then add water and other additives; second, put into the coarse aggregate + 75% water + micro silica powder + 50% fine aggregate, mixing 15-30 seconds, and then put into the cement + additives + 50% fine aggregate + 25% water, mixing until uniform. Never add the micro silica powder into the already mixed concrete.
In addition, the use of micro silica powder should be noted that it should be used in conjunction with high- efficiency water reducing agent to achieve good results; at the same time, it is recommended to mix fly ash and finely ground slag in order to improve the construction performance of concrete. And, after the concrete is mixed with micro silica powder, early maintenance should be strengthened to prevent the concrete from producing plastic shrinkage cracks. The specific mixing amount and use method may vary according to the project demand and actual situation, it is recommended to test and adjust according to the specific situation before use.
