What Is Wbm In Road Construction?

What Is Wbm In Road Construction
WBM road means water bound macadam road. The wearing surface of WBM road consist of clean and crushed aggregates which are mechanically interlocked by rolling operation. The material is bound with filler material (which are also called as screenings) and water, laid on prepared base course.

What is difference between WBM and WMM?

Difference Between WMM and WBM Road – Here are the differences between WMM (Wet Mix Macadam) and WBM (Water Bound Macadam) roads.

WMM Road WBM Road
WMM roads are more durable. WBM roads are less durable.
WMM roads get dry very fast WBM roads take time to get dry.
It can be constructed at a faster pace. It took more time to construct.
It consumes less water. It consumes more water.
In WMM roads stone aggregates and binders are used. In WBM roads stone aggregates, screenings, and binder material (Stone dust with water) is used.

Water Bound Macadam Road

What is a WBM?

What is a WBM file? – Black and white bitmap image used by mobile devices such as PDAs and cell phones; can be transferred between phones via SMS text messages; similar to a,BMP file, but only supports monochrome images. More Information Wireless bitmap files more commonly use the,WBMP extension.

What is WBM test?

Know More About Test – WBM(Water Bound Macadam) conventional method and WMM(Wet Mix Macadam) modern technology- are base course layers for Pavement/Road design. In case of WBM stone aggregates and binders are overlaid on one another at the time of construction.But in case of WMM,aggregates and binding materials are premixed in a batching plant or in a concrete mixing machine and then brought to the site for overlaying and rolling.

Sr No. Particulars Sample Size required Minimum Time Reuqured Tests As Per Indian Standard
1 Job Mix formula for GSB Agg Each size- 100 kg 02 Days MOTRH
2 Job Mix formula for WMM Agg Each size- 100 kg 02 Days MOTRH
3 Field Density test by sand replacement Note: Transportation extra and Min 10 Point per Visit Agg Each size- 100 kg 02 Days IS 2720

What is the unit of WBM and WMM?

Why is Wet Mix Macadam used? – A wet mix macadam road is more durable than a WBM road. The WMM roads dry faster than a WBM road and can be opened to traffic in less time, whereas WBM road takes a month to get dry. Even the construction of WMM road is faster.

Water-bound Macadam (WBM) materials consist of stone aggregates, binders, and screening materials. In a WMM, only stone aggregates and binders are used. The Stone aggregates are larger when used in WBM and vary from 90 mm to 20 mm depending upon the grades. However, in WMM, the stone aggregates are smaller, and the size varies from 4.75 mm to 20 mm.

While the measurement in WBM is in cubic meters, the WMM is measured in square meters.

What is GSB size?

GSB :- Granular sub base or GSB is a typical layer adopted in highway construction, which is laid above the subgrade and below the crust materials. Naturally available material consisting of various grades may be used for GSB, the largest grain size up to 65mm.

What is GSB and WMM?

Basic concept of pavement analysis and design

Bituminous pavement

The subgrade is a compacted soil layer. The base and sub-base course could be made up of bound or unbound granular layer. As per Indian specifications (), some examples of base or sub-base layers are: Granular sub-base(GSB), Water Bound Macadam (WBM), Wet Mix Macadam (WMM) etc. The binder course is made up bituminous material. As per Indian specifications (), some examples of binder course are: Bituminous Macadam (BM), Dense Bituminous Macadam (DBM) etc. The wearing course is the top bituminous layer which is comes in contact to the vehicle tyre. Wearing course provides impermeability to the pavement surface against water percolation (). The binder course and wearing course together are called bituminous surfacing.

/td>

/td>

table>

Basic concept of pavement analysis and design

What is the thickness of WBM road?

The WBM Course shall be constructed in layers such that thickness of each compacted layer is not more than 100 mm for grading 1. The compacted thickness of layer shall be 75 mm for grading 2 and grading 3.

What is the size of WBM?

The oldest type of highway pavement used in modern times is known as Macadam after the name of Johan Macadam, a Scottish Engineer. The term Macadam in the present time means the road surface and base constructed of crushed or broken aggregates cemented together by the action of rolling and water.

The binding action in WBM is achieved by stone screening used as filler in the presence of water. Water bound macadam is constructed in thickness varying from 8 to 10 cm depending upon the design requirements. The surface course of WBM gets deteriorated very soon under the action of mixed traffic. So nowadays the WBM is used as a base course for the superior type of pavement such as bituminous or cement concrete surfacing.

Generally, the layers in WBM are laid in 12 to 15 cm thickness. The total thickness may be up to 30 to 35 cm depending upon the design requirements. Each layer is compacted to 75 to 80% of its loose thickness by smoothed wheel roller. In WBM roads generally, camber is provided of the order of 1 in 36 to 1 in 48.

Where WBM roads are used?

The term ‘ Macadam ‘ in the present day means, the pavement base course made of crush or broken aggregate mechanically interlock by rolling and the voids fill with screening and binding material with the assistance of water, WBM roads may also be use as a sub base, base course or even surfacing course of low volume roads,

How many types of WBM are there?

Materials Required For WBM Road Construction. – There are mainly 3 types of materials which are used in the construction of WBM road.

Course Aggregate Screenings (filler material) Binding Material