Thursday, November 21, 2013



     The timber which is to be used for the structural purposes is to be dressed, planed.  Framed and placed in proper position. The term carpentry includes can  forms of  construction which have to resist stresses due to loads coming upon them. Thus a carpenter constructs permanent timber works such as roofs, floors, etc as well as  temporary timber works such as  scaffolding, shoring, centering , etc.
     The term joinery is used  to indicate the art of preparing I internal fittings and finishing’s of timber. Thus a joiner constructs timber works such as doors, windows,  stairs, floor boards, furniture, cupboards, etc. Thus the joinery is used for delicate c instruction requiring precise workmanship  for enhancing the architectural beauty of timber.
     In India , the  word carpentry is used only to incite both types of trades, namely, carpentry an joinery and the workman who is employed for the work of  carpentry and  joinery is known as a carpenter.
    In this chapter, the salient features of carpentry and joinery   will discussed.


The  cement concrete possesses the following important properties :
1)      It had a high compressive strength.
2)       It is free from corrosion and there is no appreciable effect of atmospheric agents on it.
3)      It  hardens with age and the process of hardening continues for a long  time after the concrete had attained sufficient strength. It  is this property of cement concrete which gives it a distinct place among  the building materials.
4)      It is proved to be more economical than steel. This  is due to the fact that sand and pebbles or crushed rock, forming the bulk of cement concrete, to the extent of about 8% to 90%, are usually available at moderate cost.  The form work, which is of steel or timber , can be sued over and over again or for other purposes after it is removed.
5)      It binds rapidly with steel and as it is weak in  tension, the  steel reinforcement  is placed in cement concrete at suitable places to take up the tensile stresses.  This is teemed as the Reinforced Cement Concrete or simply  R.C.C.
6)      Under the following two conditions,  it had a tendency to shrink :
a)      There is initial shrinkage of cement concrete which is mainly due to loss of water through forms, absorption by surfaces of forms, etc.
b)       The shrinkage of cement concrete occurs as it hardens. This tendency of cement concrete can be minimized by proper curing of concrete.
c)        It had a tendency to be porous. This is due to the presence of voids which are formed during and after its placing. Following two precautions are necessary to avoid this tendency. :
There should be proper grading and consolidating of the aggregates. The minimum water-cement ration should be adopted.
7)      It forms a hard surface, capable of resisting abrasion.
8)       It  should be remembered that apart form other materials, the concert e comes to the site in the form of raw materials only. It  final strength and quality to the site in the form of raw materials only. It final strength  it. However the depend entirely  and local conditions and persons handling it. However the materials of which concrete is composed may be subjected to rigid specifications )

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