What is the active mineral admixture? What are the varieties?
The active mineral admixture is the pozzolanic admixture, with silicon oxide and aluminum oxide as the main components. It does not have or have only very low gelling properties itself, but in the presence of water, can be chemically combined with calcium hydroxide to generate hydrates and hardened in air or water. With natural mineral materials or industrial wastes as raw materials, the active mineral admixture can be used directly or finely ground beforehand as a component of concrete or mortar to improve its performance and save cement.
Since mineral admixtures have a certain improving effects on the performance of mortar, can take full advantages of these industrial wastes, enhance the comprehensive utilization of resources, improve the greening level of ready-mixed mortar, protect the environment and reduce the production cost of mortar, it is advocated to add with an appropriate amount of mineral admixtures. Its dosage should be consistent with relevant provisions and determined by the test.
The commonly used active mineral admixtures are fly ash, granulated blast furnace slag powder, silica fume and zeolite powder.
In the use of mineral admixtures, take into account the performance requirements of mortar, conditions of other raw materials as well as the characteristics of mineral admixtures. In general, for the ready-mixed mortar of low strength grades, priority should be given to the choice of fly ash, while for the ready-mixed mortar of high strength grades, the compound use of slag powder and fly ash may be considered; when the aggregate gradation is poor, a relatively large amount of high quality fly ash should be considered to improve the operability of mortar; in the preparation of wet-mixed mortar, priority should be given to the use of fly ash; in winter construction, an appropriate increase in the dosage of slag powder should be considered; when the machine spraying process is used, the dosage of fly ash should be appropriately increased to increase the viscosity of mortar and reduce falling ash.