Hardcast is a range of silica based acid resistant materials. Hardcast Light is the cellular insulation version.
Hardcast Light is virtually impervious. It consists of Hollofill; small ceramic hollow spheres, in a dense impervious acid resistant silica matrix. It is prepared by mixing powder and a liquid binder, to a pourable consistency. It sets in roughly an hour.
Hardcast Light is essentially silica, 78% pure. Totally inorganic.
The particles are all fine; the largest particle size being 350micron.The particles cannot easily be discerned with the naked eye.
The density is very low, 1,l to 1,2g/cm3 after drying at 4000°C.
The apparent porosity is 15%. The pores are all very fine, resulting in very low permeability. The true porosity is high, in the region of 50%, giving about 35% volume of totally closed pores.
Hardcast Light is a very efficient thermal insulator, due to its low density, impermeability and ultra-fine closed porosity.
It is almost impervious. This can easily be demonstrated by the tongue test. It does not adhere to the tongue at all. It has the feel of glass when tested by the tongue.
Hardcast Light starts deforming by melting at around 1100°C.
The only acid which rapidly attacks Hardcast is hydrofluoric acid. Hardcast is dissolved by alkaline solutions.
The very low permeability of Hardcast Light ensures that gases barely penetrate it. Deposition of solids in the material cannot exceed 15% by volume.
As the name implies, Hardcast is a hard, strong material. It may slump under pressure before it is dry.
The set is an irreversible chemical reaction, and is not easily disturbed by contamination. Set is considerably accelerated by high ambient temperatures. The surface will rapidly set and form a skin byair-drying. This skin is not chemically set and is not acid resistant. The skin should be scraped off if it forms while still placing the material. The skin may shrink and tear under conditions of lowrelative humidity. To prevent this, place plastic sheet on top of the skin immediately after it has formed.
Powder and binder are mixed to a pourable consistency, and poured into place. The shuttering must be well sealed, as the material is fine and fluid. No vibration is required.
The material can develop no major structural defects when installed by pouring into sound shuttering.
Mixing by hand is possible. Mixing by shovel on the floor is not possible as the mix is too fluid. Pan mixers should have a door seal in good condition. The ratio of powder to liquid binder is 100 parts to 70 parts.
Hardcast Light is ideal for pumping.
For applications under heat, drying out should proceed slowly to 400°C. The low permeability should be borne in mind to prevent steam explosions. Drying may start immediately. Fluffy white efflorescence may grow from the surface. It is not a problem, and can be washed off. Colour; Light grey.
Silica is known to be a respiratory hazard. Hands should be washed at frequent intervals while installing Hardcast, as it sets rapidly due to the warmth and evaporation. After use, apply skin cream several times. Prolonged exposure will cause hands to feel rough and dry, the same as with portland cement. Binder will burn if it enters a cut or the eyes. Wash eyes thoroughly with water. Binder is not harmful if swallowed, but has an unpleasant soapy taste.
Hardcast Light powder is supplied in 15kg plastic bags, wire tied. Hardcast Binder is supplied in 33,3 kg plasic drums.
The wet density is 1,36tons per cubic meter, and orders should be placed for the total mass. Powder and binder will be correctly proportioned by the supplier.
Thermal insulation where acids are present. Gas tight sealing in any application up to 1000°C. Protection of steelwork against corrosive gases, hot of cold.