What is cement quick-setting agent and how to use it?
TIME：2019-07-11 READER：297
Cement accelerators are produced with the widespread use of cement concrete and are constantly evolving. The application of cement quick-setting admixture in shotcrete can greatly increase the speed and thickness of the jet, while increasing the strength and reducing the rebound. The cement quick-setting agent enables the concrete to condense quickly after it is sprayed onto the work surface.
First, the cement quick-setting agent should have the following properties:
1. No adverse effects on concrete, such as steel rust, alkali-aggregate reaction, long-term durability, etc.
2, have a higher early strength, the late strength reduction can not be too large (less than 30%);
3. Initially set the concrete within 3 to 5 minutes after the concrete is sprayed out, and finally set within 10 minutes;
4. Minimize the water-cement ratio to prevent excessive shrinkage and improve impermeability;
5. Make the concrete have a proper viscosity to prevent the rebound from being too high;
6. No adverse effects on construction workers and the environment, no corrosive effect on steel bars;
7, raw materials are easy to get, the price is lower.
Second, the use of cement accelerator:
Cement accelerators are mainly used in shotcrete and trapping projects. Shotcrete can be used in tunnels, underground roadways and other projects to achieve fast, high quality. How to incorporate the accelerator should be determined by the process conditions.
When dry shotcrete is applied, when the cement, coarse aggregate and fine aggregate are added, the powdered quick-setting admixture is added at the same time, and these materials can be evenly stirred by the compressed air. The powdered quick-setting coagulant can be used in wet spraying, but it needs to be added as a compressed gas stream at the nozzle and cannot be directly added to the wet jet or pump. The liquid quick-setting admixture is first dissolved in water during spraying, and is diluted with water in an appropriate amount after spraying, and is added at the nozzle by means of a water pump or a wind pressure, so that it is easy to make the quick-setting admixer uniform.
An appropriate amount of quick-setting admixture is added to the silicate cement. The cement paste has plasticity at an appropriate water-cement ratio and appropriate temperature, and the setting time can be controlled within 10 minutes. The general requirement for the quick-setting admixture is that the pure pulp has good fluidity, and it does not appear to be rapidly dry and thick and non-plastic.
First, the cement quick-setting agent should have the following properties:
1. No adverse effects on concrete, such as steel rust, alkali-aggregate reaction, long-term durability, etc.
2, have a higher early strength, the late strength reduction can not be too large (less than 30%);
3. Initially set the concrete within 3 to 5 minutes after the concrete is sprayed out, and finally set within 10 minutes;
4. Minimize the water-cement ratio to prevent excessive shrinkage and improve impermeability;
5. Make the concrete have a proper viscosity to prevent the rebound from being too high;
6. No adverse effects on construction workers and the environment, no corrosive effect on steel bars;
7, raw materials are easy to get, the price is lower.
Second, the use of cement accelerator:
Cement accelerators are mainly used in shotcrete and trapping projects. Shotcrete can be used in tunnels, underground roadways and other projects to achieve fast, high quality. How to incorporate the accelerator should be determined by the process conditions.
When dry shotcrete is applied, when the cement, coarse aggregate and fine aggregate are added, the powdered quick-setting admixture is added at the same time, and these materials can be evenly stirred by the compressed air. The powdered quick-setting coagulant can be used in wet spraying, but it needs to be added as a compressed gas stream at the nozzle and cannot be directly added to the wet jet or pump. The liquid quick-setting admixture is first dissolved in water during spraying, and is diluted with water in an appropriate amount after spraying, and is added at the nozzle by means of a water pump or a wind pressure, so that it is easy to make the quick-setting admixer uniform.
An appropriate amount of quick-setting admixture is added to the silicate cement. The cement paste has plasticity at an appropriate water-cement ratio and appropriate temperature, and the setting time can be controlled within 10 minutes. The general requirement for the quick-setting admixture is that the pure pulp has good fluidity, and it does not appear to be rapidly dry and thick and non-plastic.
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