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Showing posts from April, 2013

Cement concrete pavements, pre-stressed pavements

Cement concrete pavements: 

Cement concrete pavements comes under the category of the rigid pavement, due to the higher flexure strength of the concrete slab. CC pavements have the longer life, because of the higher durability and high load carrying capacity.CC pavements require very less maintenance, so the maintenance cost is reduced.CC pavements have very good aesthetic appearance.
There are some disadvantages of the CC pavements,

Initial cost of construction of the CC pavements is very high. The provision of the joints is mandatory.Pre-stressed concrete pavements: Pre-stressed concrete pavements are constructed by using the pre-stressing techniques. The lower layer of the concrete slab is compressed from its normal state, with the help of the high tension cables. The cable are laid on the position and are applied with the high tensile stresses on both the sides. When the bar is in the tension state, the concrete is poured in and is allowed to set.  When the tension arrangement of th…

Construction of WBM roads, WMM - Wet mix macadam - Transportation Engineering

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Hi, Here we are going to discuss the construction of the WBM and WMM roads in brief. 


(I) - WBM (Water Bound macadam)  roads construction:
The water bound macadam road construction technique was given by the John Macadam. This technique in present day is used as given below. For WBM construction we use three materials:
AggregatesScreenersBinders.Aggregates: We use the aggregates of different grades. IRC(Indian Roads Congress) has classified the coarse aggregates into 9 grades, according to their size.
For the construction of the WBM roads aggregates are used in the sub-base, base and surface course and so the aggregates are divided into 3 grades according to their size. Grade 1 - particles of size 90 mm to 40 mm. Grade 2 - particles of size 63 to 40 mm. Grade 3 - particles of size 50 to 20 mm. The grade 1 aggregates having size of 90 mm to 40 mm are preferred for the sub-base material and grade 2 for the base and grade 1 for the surface course. However, if we only use the WBM as the surface cou…