Materials
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Rice husk

Rice husk

Product composed of the bracts (glumes and lemma) that surround and adhere more or less tightly to cereal grains, particularly rice husk (also known as pulone), which results from the initial dehusking operations.

The processing of rice generates a large amount of waste material: for ever ton of processed rice about 270kg of waste are produced, (200kg of rice husk and 70kg of bran) in addition to the straw. Rice husk, the “skin” of the rice grain, is one of the most interesting waste materials, as we at Archingreen have also been able to experience.

Features:

Thermal and acoustic insulation
Breathability and hygrothermal comfort
Sustainability
Durability
Biodegradability

Applications:

Thermal and acoustic insulation material
Natural mortars and plasters
Artificial wood
Rice husk ash for cements

Breathability (μ)

≤ 3

Ability of a material to be passed through by water vapor
Protect yourself from condensation and mold: the lower its value, the greater your ability to dispose of internal moisture
Thermal Conductivity (λ)

0,051-0,053 W/mK

The ability of a substance to transmit heat
To defend against the cold: the lower its value, the greater the insulation capacity
Specific Heat Capacity (Cp)

1.480 J/KgK

Amount of heat required to raise the temperature of a substance by one degree
To protect against heat: the higher its value, the slower it accumulates heat
Density (ρ)

125 Kg/m3

How is the mass of a material distributed in the space it occupies
To defend against heat: the greater its value, the greater its ability to defend against heat

As every traditional agro-food product, there is a highly specific technical vocabulary to identify every little part of a plant and each stage of the processing. It is essential knowing some of this terminology to understand what rice husk is.

Paddy rice, or unprocessed, threshed rice, undergoes dehusking, a sort of peeling process where the discarded part is “pulone” or rice husk. Rice husk makes out about 17% to 23% of the total weight of puddy rice depending on the variety.

The husk’s function is to mechanically protect the grain, prevent water loss and block UV rays allowing for gradual growth.

Beige-brown in color, it has a harder and more resistant texture, is light and bulky, with a density ranging between 120 and 140kg/m³. mainly composed by cellulose and hemicellulose (45% of the mass) rice husk is insect resistant, does not rot and does not mold.

Thermal and acoustic insulation

Rice husk has a low thermal conductivity, making it an excellent natural insulator.

Lightly, irregularity and porosity of rice husk, made up largely of cellulose, makes it highly effective for acoustic insulation.

Breathability and hygrometric well-being

As a natural material is breathable and a ensures hygroscopic comfort: it permit to the house to breathe in every temperature conditions.

Sustainability

As an agricultural waste product does not require additional processing for use, and due to widespread rice production across Italy, transport consumption can be also minimized.

Durability

Resistant to mold, fungi ad parasites thanks to his high silica content.

High silica content maker rice husk heat-and-fire resistant.

Biodegradability

Even at the end of its life cycle, it has a minimal environmental impact: it is completely biodegradable so it easy to dispose of.

Applications

Thermal and acoustic insulation

Rice husk is used like an insulating material for walls, roofs and floors, thanks to his fibrous and lightweight structure that provides excellent energy performance.

It can also be injected directly into wall cavities. There are also rigid panels made from compressed husk often combined with other natural materials which are suitable for interior and exterior cladding systems.

Natural mortars and plasters

Rice husk is mixed with lime or clay for natural mortars production, used as plasters, screeds and subfloors, known for their lightly, breathability and insulating properties.

Artificial wood

Husk can be substitutive to the main component in bio-composite materials as a substitute for woods, with excellent resistance to parasites, mold and cracking.

Rice husk ash for cements

The ash obtained from burning rice husk is very rich in silica and can be used as a pozzolanic material in concrete and cements: it makes cement lighter, stronger and more workable.

Explore other materials

Rice husk

Features:

Applications:

Thermal and acoustic insulation

Breathability and hygrometric well-being

Sustainability

Durability

Biodegradability

Applications

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Cork

Lime

Common reed

Cellulose