26 Mar,2019 UTC+8 Views:
1. The amount of slag powder
Single-slag powder is generally 30% to 50%. When double doping, the slag powder is within 20% and the slag powder is within 30%. In the initial use, good mineral powder is controlled within 10%~20%. Later, through the trial and adjustment step by step. The amount of mineral powder is too high and the viscosity is large, which is not conducive to the construction of slag, and also prolongs the setting time of slag, especially for those vertical structures. Because the slag is in a plastic state for a long time, it is easy to cause plastic cracks. However, for large-volume slag, it is advantageous because it reduces the heat of hydration. However, the amount of mineral powder should not exceed 70%. As for the condensate condensing time, it is only necessary to pay special attention to the amount of mineral powder during winter construction. In addition, the dosage of early strength agent should be appropriately increased.
2, should strengthen the test, strictly control the fineness of the mineral powder
The large-scale slag vertical mill production line, the fineness of the produced slag powder is controlled within the range of 400 ~ 500m2 / kg. Due to its advanced production process, the fineness of the mineral powder is very stable. However, the fineness of the ball milled slag powder is difficult to reach 400 m2/kg or more. If the milling time is extended to barely reach 400 m2/kg or more, it is difficult to stabilize for a long time. Once the fineness of the slag powder drops, it will bring many problems to the slag, such as plasticity decline, segregation and bleeding, prolonged clotting time, early strength reduction, and even 28d strength will be reduced to varying degrees. Therefore, when using ball milled slag powder, the inspection should be strengthened to strictly control the fineness of the ore powder.
3. When complex doping, select the appropriate compound ratio for different grades of slag powder.
When the ore powder is used in a slag mixing station, it is often used in combination with mineral powder. This is because mineral powder is cheaper than mineral powder, and single mineral powder is not good for slag cost. Although the single mineral powder can greatly reduce the cost, the dosage is greatly limited; in addition, when the mineral powder and the mineral powder are used in combination, the "complementary complementarity" of the two can be fully utilized to improve the slag performance.
4. Maintenance of slag during complex mixing
The maintenance problem after compounding is very important for the quality of slag. The slag maintenance after the mineral powder and mineral powder is mixed is not enough (humidity is less than 80%), the hydration of cement is almost difficult to carry out, the strength development is very slow, and the early strength is low, which easily causes the plastic crack of the slag. For most construction sites, due to the construction schedule, structural form, maintenance methods and personnel quality, the maintenance has not received good attention, especially the vertical structure. If the maintenance is not good, cracks are likely to occur.
5, pay attention to adjust the slag condensation time
Compared with ordinary slag without mineral powder, the mixing time of slag powder to slag has a certain retarding effect, and the initial setting and final setting time of slag is delayed by 1~2h than the standard slag. Therefore, attention should be paid to adjusting the setting time of slag, especially in winter construction. The slag mix ratio should be adjusted, the amount of ore powder in the slag should be controlled and the early strength type water reducing agent should be used.