Unit weight of Engineering Materials
Unit weight means weight of material per unit volume(1 m3 or 1m x 1m x 1m ).
Unit weight of cement : 14.40 KN/m3
Unit weight of Sand :17 KN/m3
Unit weight of Aggregate :15 KN/m3
Unit weight of Brick Masonry :19.20 KN/m3
Unit weight of Brick Stone :20.80 to 27 KN/m3
Unit weight of Steel :78.50 KN/m3
Unit weight of Wood :12 KN/m3
Unit weight of Plain Cement Concrete : 24 KN/m3
Unit weight of R.C.C : 25 KN/m3
Unit weight of Water : 10 KN/m3
Precautions taken while storing Cement:
- the first and most important is that cement should not be stored in moist conditions means the storing room should be well proof against any ingress.
- must be stored in air tight containers or polythene bags.
- maintain some 1m distance away from walls for keeping cement bags.
- the surface where cement bags are kept must be damped proof or keep it on any tarpaulin sheet.
- the cement bags must be arranged in header and stretcher form.
- the maximum height of keeping cement bags should be kept in between 6 to 10 bags.
- or for any extra safety we can use moisture removal conditioners.
- But its better to use cement bags as early as possible.
Short note on Timber?
Timber is a technical name given to wood, when the circumferential distance of wood is not less than 600mm. But word timber means “to build”. Hence timber is a building material and used for engineering purposes. A well-seasoned timber has a moisture content less than 15%. It is a valuable/costly material, as it is not available easily in many parts of country because getting 600mm circumference for a tree takes many years.
Two important defects caused by fungi are:-
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- Dry rot:- This happens when there is a lack of ventilation means no free circulation of air.
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- Wet rot:- This happens when there were alternate dry and wet conditions.
The explanation is for 1st year students, as the word shows ‘seasoning‘ means removal of water in presence of proper air circulation under controlled conditions and while seasoning, water does not exceed 15% of its dry weight.
Following benefits are:-
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- to make it durable against cracks, warp and sharp.
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- to make it fit for receiving treatments of paints, varnishes, preservatives, etc.
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- to make it workable for various operations while construction work.
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- to increase strength, hardness and stiffness against rough use.
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- increase electrical resistance power.
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- to make it suitable for joining with other types of timber.
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- to make it suitable for burning as a fuel.
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