PRESERVATION MEASURES

TO REMEDY FROM

TIMBER ROT

Common used engineering materialCommon used engineering material

Has less strength in green Has less strength in green

Strength can be increased by Strength can be increased by seasoningseasoning

Shrinkage should be eliminated before Shrinkage should be eliminated before useuse

INTRODUCTION

Alternate dry and wet conditionsAlternate dry and wet conditions

Defective seasoning of the timberDefective seasoning of the timber

Fungi developing diseases such as rotsFungi developing diseases such as rots

Insects such as marine borers, beetles, Insects such as marine borers, beetles, termites etctermites etc

Lack of ventilationLack of ventilation

Dark and damp conditionsDark and damp conditions

DECAY OF TIMBER

Decay of timber is not chemical action Decay of timber is not chemical action

Timber in dry and well ventilated place Timber in dry and well ventilated place or continuously submerged under fresh or continuously submerged under fresh water last for long timewater last for long time

Wood embedded in ground should be Wood embedded in ground should be treated with creosote, coal tar or treated with creosote, coal tar or chemicalschemicals

Rots disintegrate timber and produce Rots disintegrate timber and produce HH22S and COS and CO22 gases gases

DECAY OF TIMBER

Rot due to certain fungi which feed on wood and convert them into fine powder

Dry rot is due to certain species of fungi

DRY ROT

DRY ROT IN SUB FLOOR VOID WET ROT IN SUB FLOOR VOID

not properly seasoned timber

warm moist conditions

confined atmospheric condition

unseasoned timber if tarred, charred or painted

DRY ROT

Decomposition of timber due to moisture where timber converts into grayish brown powder

Some reasons for wet rot are:

alternate wet and dry conditions

unseasoned timber exposed to rain and wind

WET ROT

Protect timber structure from attacks of fungi and insects, borers, termites and marine organisms

Prolongs the life and durability of timber structures

Preservatives are painted, sprayed or impregnated

PRESERVATION OF TIMBER

Most efficient means is good seasoning and free circulation of fresh air

Leaks in water supply pipes, rain water and drains should be avoided

Timber should be kept dry during construction and also protect timber from getting damp after construction

PRESERVATION OF TIMBER

Prevent dampness to timber floor (DPC) and ventilate the space below and around the timber floor

Exposed timber can be preserved by impregnation of poisonous chemicals to fungi

Protect against moisture by oil paint

PRESERVATION OF TIMBER

There are three types of There are three types of preservativespreservatives:

i. Oil typei. Oil type

ii. Chemical (organic solvent) and ii. Chemical (organic solvent) and

iii. Water soluble preservativesiii. Water soluble preservatives

Coal tar, oil paints, creosote oiCoal tar, oil paints, creosote oil are are most common used preservativesmost common used preservatives

PRESERVATIVES

Should be cheap, durable, unaffected by heat and light, non combustible and easily available

Smell should not be very unpleasant

Safe

Should not affect strength and outlook

Should offer high resistance to moisture

Should efficiently kill fungi and insects

QUALITIES OF PRESERVATIVES

Charring Charring – Kept wet for ½ - 1 hrs and – Kept wet for ½ - 1 hrs and then burnt to depth about 15mmthen burnt to depth about 15mm

TarringTarring – Applying hot tar in the – Applying hot tar in the surfacesurface

- Mainly used for submerged surfaces- Mainly used for submerged surfaces

PaintingPainting – Makes timber beautiful and – Makes timber beautiful and also prevents white ant attack also prevents white ant attack

METHODS OF PRESERVATION OF TIMBER

In sewers / drains made from concrete, the sewer acids causes corrosion of concrete

Ground water with concentration of alkaline salts is harmful to sewer pipes

Sulphate resisting cement or high alumina cement is recommended

Seawater has same effect

Mixture of air and sea water rapidly corrodes concrete and steel

CORROSION OF CONCRETE

Protection

lining pipes with clay tiles

using stoneware pipes

jointing materials can be from resisting cement or high alumina cement

Use of coal tar or bitumen

CORROSION OF CONCRETE