Acoustical Materials

STRAWStraw is the inedible chaff, or stalks, of grain grasses such as wheat, rice, barley, and rye, and has been used by farmers for generations as animal bedding and for visual and sound barriers for their homes and fields

● Straw can be used in the form of panels or bales

● Straw-bale is also used as construction material

● Straw also can be sewed into a frame to make panels

● fragile but flexible material is easy to work with

● full sound absorption, attenuation and sound transmission is seen

● available in various sizes

Strawbale wall detail

● provides noise reduction through sound absorption

● provides thermal insulation, reduces ceiling maintenance

● is lightweight ● is very low of cost● is easily available● natural and eco friendly● not a conventional material● should be well protected from water.

pros and cons

COIR FIBRECoir Fibre is obtained from the husk of the coconut. It is suitable as a substitute to synthetic fibres and wood-based materials for acoustic absorption purposes. These fibres have many advantages because they are cheaper, renewable, non-abrasive and do not give rise to health and safety issues during processing and handling. It is being used in tropical areas like Kerala for some time.

● Coir is gold hued, naturally lustrous and fibrous in terms of texture.

● It is available in tropical areas like Kerala, Goa, etc.

● It is used in combination with perforated panels and these panels can then used for acoustical treatment.

● Available sizes of perforated panels - 1000mm x 2000mm, 1250mm x 2500mm, 1500mm x 3000mm.

● Tiles and Mattings are also made out of coir which make good sound absorbing materials.

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pros and cons

● is strong, brittle and light-weight.

● 100% biodegradable.

● no potential health and safety risk during processing and handling.

● is available in abundance.

● absorbs sound and reduces noise.

● can be recycled.

● not very durable.

● not very popular; can become difficult to source.

CORKCork is a prime subset of bark tissue that is harvested for commercial use.Cork can be separated from trees without causing permanent damage.It is an impermeable, buoyant material.

● Cork is very easy to install.● It is used in buildings where it is

necessary to reduce noise transmission from floor to floor or from room to room.

● Acoustic cork deadens the impact noise, such as that made by high heel shoes on hardwood floors, ceramic, marble or stone flooring.

● Cork wall panels and cork ceiling tiles are used for acoustical treatment.

● It can help absorb and dissipate sounds to reduce disruptions and improve the acoustics in a room.

pros and cons

● is very light-weight.

● is durable and long-lasting.

● is renewable.

● is resistant to dust and toxin absorption.

● is inexpensive.

● without proper protection, it can stain.

● it is not water-proof.

MOSSMoss is a natural lichen which can used indoors as well as in shaded outdoor areas. It needs a min. relative humidity of 40%, and does not require any maintenance, light or water. It blends with other acoustic materials like ceramic, wood, PVC, EPS etc. It has an absorption value of around 1.0.

● Moss panels are attached to a base (eg-MDF, aluminium) with an acoustic layer of natural fibres.

● It is available in various sizes like 30cmx30cm, 80cmx80cm, and can be attached with or without seams.

● It could enhance the ‘Green’ quotient of buildings.

● It is a lichen and hence has a grass like appearance.

● It is available in various colours.Method of installation

Pros

● easy installation and requires no maintenance

● high performance acoustic insulator

● bio-degradable, non-toxic, available in colours

● compliments other materials

● Dust repellent/ does not attract fungal attacks

● Delays the spread of fire

Cons

● High initial cost

● Technology mostly in development stage

● Environmental factors needs to be taken care of.

HempcreteHempcrete is a bio-composite made of the inner woody core of the hemp plant mixed with a lime-based binder. The hemp core has a high silica content which allows it to bind well with lime.It is not used as a structural element, only as insulating infill between the frame members though it does tend to reduce racking. All loads are carried by internal framing. Wood stud framing is most common making it suitable for low-rise construction. Hempcrete buildings ten stories high have been built in Europe.

The material is mixed in mortar mixers for 1-2 minutes and stuffed by hand into the wall cavities. The wall is slip-formed with temporary wooden or plastic “shuttering” forming the inner/outer surface forms.

Construction costs may be reduced by:Shallower foundations30-40% less lumber, labour in

framingLower transport costs of materials

to siteReduced mechanical (HVAC)

requirements

ProsThermal Mass InsulationDurable and RecyclableNegative CarbonHigh Thermal Resistance Design Flexibility (adjustable

thickness)Fire and Pest Resistant (NO Termites)Significantly Reduce Co2 EmissionsInherently AirtightNo Waste (re-build or fertilise)ZERO LANDFILL

● Hempcrete breathes well, and care must be taken to maintain it.

● Only lime-based paints can be used.

● They are more expensive and more difficult than the modern latex acrylic paints.

Cons

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