Water bound macadam, Civil Engineering

Water Bound Macadam:

Water Bound Macadam (WBM) is a dense and compact course of a road pavement composed of stone aggregates held together by a film consisting of gravel or screenings with a minimum amount of water.

The stone aggregates are of three gradings.

553_Water Bound Macadam.png

Table : Grading of Stones For WBM

Grading 1 is used in the lower layers, and gradings 2 and 3 are used in the middle and top layers respectively. Stone aggregates, over-burnt brick ballast and Kankar can be used. The loose thickness of the aggregates will be about 120-140 per cent of the compacted thickness. The quantity of screenings and binding material required is about 0.23-0.35 cu m per 10 sq m of area, depending upon the grading selected. The construction follows the sequence of steps as below :

(a) spread the aggregates manually

(b) dry rolling

(c) wet rolling

(d) application of screenings, watering and rolling

(e) application of binding material, watering and rolling

(f)  spreading a thin layer of coarse sand and light-rolling

The rolling operations shall begin with the outside rear wheel covering parts of the shoulder and coarse aggregates, the roller moving forward and backward, the overlap of rear wheel being half its width in each pass. About 4 passes on the aggregates plus four passes after the screenings are applied should be adequate.

WBM is now used only for low volume roads.

Posted Date: 1/22/2013 4:37:35 AM | Location : United States







Related Discussions:- Water bound macadam, Assignment Help, Ask Question on Water bound macadam, Get Answer, Expert's Help, Water bound macadam Discussions

Write discussion on Water bound macadam
Your posts are moderated
Related Questions
Need to know about compressive strength test and tensile strength test of cement

determine the reaction and draw shear

Maximum shear stress - state of stress: Consider the state of stress. (a) According to principal stress theory the equivalent stress for this case is simply σ 1 , i.e. 300

briefly explain the stacking of materials in the site for general building

construction the ellips in all method

I would like to know if anyone can help me with my const estimating project

Can I get an online project to work on in civil engineering??

Explain the Scaling - underwater inspection of bridges? Scaling is the gradual and continuing loss of the surface mortar and aggregate over an area. This condition is commonly


Explain the Methods of Underwater Inspection? There are three common methods of carrying out underwater inspection of bridge elements. a)  Wading inspection b)  Scuba div