Building construction-5

Insulating material- SAWDUST

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Sawdust or wood

dust is a by-product of cutting, grinding, drilling, sanding, or otherwise pulverizing wood with a saw or other tool.

It is also the byproduct of certain animals, birds and insects which live in wood, such as the woodpecker and carpenter ant.

Material origin

sample Average particle/ fibre size (m)

18.2 MPa 36.4 MPa 54.6 MPa

72.9 MPa

Saw dust 90 0.200 0.216 0.222 0.240125 0.198 0.212 0.219 0.232150 0.195 0.211 0.215 0.226180 0.190 0.202 0.211 0.218355 0.185 0.199 0.209 0.213

Thermal conductivity (k±0.005/W/m/K)

Wood has an R value of roughly 1.5 for softwoods and less than one for hardwoods.Softwood, you’d need about 18 inches or so to get to R-20.

chemical properties

• C-carbon content• N-nitrogen content• C:N- carbon is to nitrogen compositionCertain woods and their dust contain toxins that can produce severe allergic reactions.

Sawdust is flammable. It is water absorbant. Swells when absorbs

water and shrinks when moisture content decreases from the required amount.

Texture and colour varies from trees to trees.

Physical properties

Sawdust insulation is probably the most cost effective insulating material

available. When used to fill the space within the wall, it should be buffered with hydrated lime (three shovelfuls of lime to a wheel barrowful of sawdust). Lime acts as a preservative, an insecticide, and a dehydrator.

Any sawdust added to the basic 2 1/2 to 1 mortar mix (the ratio of aggregate to cementing material) will lower the compression strength of the wall. However, I feel you can safely add 50 percent of the total volume in sawdust.

Using shovelfuls for measures, the following recipe will make an average mixer load: 1 part portland cement, 3 parts hydrated lime, 10 parts sandy gravel, and 7 parts sawdust. Although adding insulation to the lime mortar mix will have only a minimal effect on the R-value of the wall, the added sawdust will have two other important effects. First, by retaining moisture within the mixture, the tiny wood particles help the matrix cure more slowly, resulting in a stronger wall. Second, they build up the basic batch, thus allowing the mix to go a little further, which is a significant consideration in these times of tight money.

SAWDUST AS AN INSULATING MATERIAL

Timber cladding

Boarding

Sawdust insulated timber frame wall

Lining paperBoarding

Timber studding / PAROC eXtra Internal surface

Insulating elements

Lining paper Sawdust insulation Boarding Vapour/air barrier Internal surface 

1. Make fake snow. Mix sawdust with white paint and glue to cover holiday crafts

with simulated snow.

2. Get a grip. Winter loggers spread sawdust on their truck paths. It provides traction and strengthens compacted snow while protecting the ground underneath. 

3. Soak up spills. Keep a bucket handy for accidents. Sawdust is highly absorbent and can quickly contain spills of oil or paint. 

4. Feed your plants. Sawdust mixed with manure or a nitrogen supplement keeps your plants healthy and moist, too. 

5. Make a fire starter. Melt candle wax in a nonstick pot, add sawdust until the liquid thickens, pour into an empty egg carton, and let cool. Use the briquettes to help get a fire going. 

Other uses

6. Fill wood holes and defects. Used by professional floor refinishers, very

fine sawdust or "wood flour" makes an excellent, stainable filler when mixed into a putty with wood glue. 

7. Pack a path. Tamp sawdust into a dirt walkway to curtail erosion and create a soft, fragrant pathway through your garden or wooded lot. 

8. Chase away weeds. Sawdust from walnut wood is a natural weed killer. Sweep this variety between the cracks of your walkway. 

9. Lighten up cement. Sawdust mixed into mortar has long been used when erecting cordwood walls to aid in bonding the logs together. Do the same when casting lightweight vessels and moisture-loving planters. 

10. Clean a floor. Moisten a pile of sawdust with water and use a push broom to sweep it around the concrete floor of your garage, basement, or shop. The wet sawdust will capture and absorb fine dust and grime.

Types based on

Fineness

Dry sawdust or planer shavings properly

packed in the walls and attics of buildings afford excellent heat insulation.

During construction the brickwork had been back-plastered and a space which had been left between the bricks and the tiles was filled with sawdust insulation.

Combining sawdust with water, and freezing creates a better insulating barrier in an ice capsule.

Advantages

As it settles it becomes more dense,

decreasing the resistance to thermal  conduction. 

It isn’t fire resistant and can absorb water easily, therefore it has to be treated with lime to make it damp proof and fire resisting.

Disadvantages

Thank you