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Vermiculite is a 2:1 clay, meaning it has two tetrahedral sheets for every one octahedral sheet. It is a limited-expansion clay with a medium shrink–swell capacity . Vermiculite has a high cation-exchange capacity (CEC) at 100–150 meq /100 g.
In a study comparing lightweight expanded clay aggregate (LECA) and expanded vermiculite (EV), two materials used to make concrete, to a mycelium grown brick, the mycelium grown brick was found to be a better insulator. [13] These results are similar when comparing a different mycelium based composite with extruded polystyrene.
Lightweight expanded clay aggregate (LECA) or expanded clay (exclay) is a lightweight aggregate made by heating clay to around 1,200 °C (2,190 °F) in a rotary kiln. The heating process causes gases trapped in the clay to expand, forming thousands of small bubbles and giving the material a porous structure.
Aerated concrete produced by the addition of an air-entraining agent to the concrete (or a lightweight aggregate such as expanded clay aggregate or cork granules and vermiculite) is sometimes called cellular concrete, lightweight aerated concrete, variable density concrete, Foam Concrete and lightweight or ultra-lightweight concrete, [17] [18 ...
2:1 clay minerals crystallographic structure made of three superimposed sheets of tetrahedra-octahedra-tetrahedra (TOT layer unit), respectively. The 2:1 layer (TOT) structure consists of two silica (SiO 2) tetrahedral (T) layers which are electrostatically cross-linked via an Al 2 O 3 (), or Fe 2 O 3, octahedral (O) central layer.
The expanded material is a brilliant white, due to the reflectivity of the trapped bubbles. Unexpanded ("raw") perlite has a bulk density around 1100 kg/m 3 (1.1 g/cm 3 ), while typical expanded perlite has a bulk density of about 30–150 kg/m 3 (0.03–0.150 g/cm 3 ).
The product acts as a light weight filler in many products. The expanded microspheres are white, can be 15 to 90 micrometers in average diameter and can have a density of 15 to 70 kg/m 3. The expanded microspheres are used as a lightweight filler in composite materials such as cultured marble, in waterborne paints and crack fillers/joint compound.
Expanded polyethylene copolymers (EPC) are also known - such as 50:50 (weight) materials with polystyrene. Though other properties are intermediate between the two bases, toughness for the copolymer exceeds either, with good tensile and puncture resistance. It is particularly applicable for re-usable products. [1]