Materials Based On Nonmetallic Minerals

Basic info is found in Chapter 6.

Many loose mineral materials contain natural pores that make them useful as thermal insulation. Examples are fossil meal, perlite and vermiculite.

Materials such as Portland cement, gypsum and lime are bad insulators, but they have the potential as binders for different mineral aggregates, to make them into blocks, slabs, etc. In the same way expanded clay pellets, pumice, wood shavings and woodwool can be bound.

Aluminium powder added to cement in a mixture of lime, gypsum and Portland cement acts like yeast and forms gas within the concrete. This becomes a lightweight concrete with good insulating and acoustic properties. It is also possible to foam up a relatively normal mixture of concrete using air pressure and nitrogen.

Quartz sand is the main constituent of glass and has a very high thermal conductivity, but glass can be foamed to produce a highly insulating and stable foam glass. Glasswool also originates from quartz sand. The sand is melted and drawn out to thin fibres and used as highly insulating matting or loose wool. A similar material, rockwool, is based on the rock species diabase and lime, treated in almost the same way.

Products containing larger amounts of gypsum or lime usually have excellent moisture regulating properties. Concretes based on Portland cement most often take up and release moisture very slowly. Damage can therefore easily occur to organic materials in direct contact with it.

Montmorillonite is a clay mineral well suited to waterproofing because of its high moisture absorption coefficient. Render containing sulphur also has a high waterproofing quality.

Most mineral insulation products have weak wind-proofing qualities, and require a separate membrane or skin such as render, timber panelling, or the equivalent.

These climatic products are based on materials from resources with rich reserves. What they nearly all have in common is that their extraction often causes a large impact on nature, damaging ground

Table 14.5 Climatizing qualities of products from non-metallic minerals

Material

Composition

Areas of use

Sand

Sand

Thermal buffering, sound insulation

Concretes1

Cements, water, aggregates

Thermal buffering, sound insulation

Cement-based boards and plasters2

Cements, water, aggregates

Thermal buffering, sound insulation

Foamed concretes

Portland cement, water, sand, tensides

Thermal insulation

Aerated concretes

Cement, water, lime, gypsum, quartz, aluminium powder

Thermal insulation, moisture buffering

Lightweight concretes with mineral aggregate

Cement, water, with fossil meal, expanded perlite, expanded vermiculite, expanded clay pellets, expanded blast furnace slag or crushed pumice

Thermal insulation, sound insulation

Lightweight concretes with organic aggregate

Cement, water, with wood chips, saw dust, hacked straw, cellulose fibre or polystyrene pellets

Thermal insulation, sound insulation

Lime based plasters2

Lime, water, sand

Thermal buffering, sound insulation, moisture buffering

Gypsum boards2 and plasters

Gypsum, water. Boards are covered with a layer of cardboard and possibly added with silicon

Wind-barrieres, vapour retarders, sound-insulation, fireproofing, thermal buffering, moisture buffering

Calcium silicate sheets2

Silicon dioxide, water, lime, cellulose fibre

Sound insulation, fireproofing, thermal buffering, moisture buffering

Fossil meal, loose

Fossil meal

Thermal insulation

Perlite, expanded, loose

Perlite, possibly added with bitumen or silicon

Thermal insulation

Vermiculite, expanded, loose

Vermiculite

Thermal insulation

Quartz foam (silica aerogel)

Potassium waterglass, hydrochloric acid

Transparent thermal insulation

Foamglass

Glass (silicon dioxide, sodium carbonate, calcium carbonate etc.), manganese dioxide

Thermal insulation, damp-proofing

Glasswool

Quartz sand, soda, dolomite, lime, recycled glass, borax, phenol glue, silicone or aliphatic mineral oils

Thermal insulation, sound insulation

Rockwool

Coke, diabase, limestone, phenol glue, aliphatic mineral oils

Thermal insulation, sound absorption, sound insulation

Montmorillonite

Montmorillonite, usually between layers of cardboard

Damp-proofing

1 Discussed in Chapter 13, Structural materials.

2 Discussed in Chapter 15, Surface materials.

1 Discussed in Chapter 13, Structural materials.

2 Discussed in Chapter 15, Surface materials.

water and biotopes. The more highly refined products are, the more energy they consume in production, with associated pollution during the process.

Most mineral-based climatic materials are often chemically stable in the indoor climate. However, in many cases organic additives can cause problems by emitting irritating gases and encouraging the growth of micro-organisms. Some of the materials cause dust problems during the building process and even after the building is finished. Some raw materials include radioactive elements that lead to a higher concentration of radon in the indoor air.

As waste, mineral-based climatic materials can be considered chemically neutral; the main problem can be their volume. Attention must be given to coloured products, as the pigments may contain heavy metals.

Clean loose aggregates can be re-used, as can blocks and prefabricated units. They can also be crushed into insulating granules, which are particularly well suited to use as underlay for roads.

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