SETTING ACCELERATORS Short setting times are required to guarantee high-volume production, and to keep repair times of aggregates as short as possible. The use of a setting accelerator in cement-containing bodies allows the creation of a lattice of hardly soluble silicate compounds. This gives the components sufficient strength, and the result is that they can be removed from the moulds easily, before the cement bond develops its full potential.
Short setting times are required to guarantee high-volume production, and to keep repair times of aggregates as short as possible. The use of a setting accelerator in cement-containing bodies allows the creation of a lattice of hardly soluble silicate compounds. This gives the components sufficient strength, and the result is that they can be removed from the moulds easily, before the cement bond develops its full potential.
Chemical binders are applied in refractory bodies to reduce or even replace hydraulic binding agents. These alternative binders allow a compaction of refractory vibration bodies. After drying, these vibration bodies can be heated faster than hydraulically bonded bodies.
Thixotropic vibration bodies or self-flowing castables are often used in refractory applications. These bodies must be processed with low water contents, and good flow properties are required, which can be achieved by the use of dispersants. The desired effect is an increase in density and strength, and an improved corrosion resistance.
Flocculents are mainly used for the flocculation of silica sol (e.g. LITHOSOL 1530). Flocculents destabilise the silica sol and bring about gel formation.
Powder wetting agents permit – after their activation through the addition of water – the dispersion of hydrophobic raw materials in refractory vibration bodies (e.g. soot and graphite). Wetting agents are surface-active preparations exhibiting high surface affinity, which in turn decreases the surface tension of the preparation water.
The use of splinter porosity-inducing agents serves to adjust the pore size, pore volume and pore distribution in a targeted manner. A typical example of application is the manufacture of abrasive tools. Fibrous porosity-inducing agents are employed to reduce cracks and shrinkage and to permit faster de-watering.
