What is WBM?

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 do you mean by WBM?

The full form of WBM is Water Bound Macadam. It is the layer of road constructed from broken stone aggregates bound together by stone dust or screening material and water applied during construction and compacted by a heavy smoothed wheel roller.

What is WBM and WMM?

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.

What are the components of WBM?

What are the advantages of WBM road?

WBM Road Construction Part - 1 | Water Bound Macadam Road | Civil Technology

Which of the material is used for WBM road?

The coarse aggregates used in W.B.M generally consists of hard varieties of crushed aggregates or broken stones. However, soft aggregates like over burnt bricks metal, kankar and laterite may be used.

What is binding material in WBM?

Binding Material consisting of fine grain material passing 0.425 mm sieve is use in WBM construction thus to prevent raveling of the stones. Kankar nodules or lime stone dust may also be utilize, if locally available.

What is the density of WBM?

Effect on Maximum Dry Density (MDD): it is observed that WBM-A exhibited MDD of 20.60kN/m3 and WBM-B exhibited MDD of 22.66kN/m3, indicating 10% increase in MDD for WBM –B after partial replacement by steel slag, specific gravity of steel slag is higher compared to conventional aggregates.

What is WBM pavement?

Full form of WBM is Water Bound Macadam. It is the layer of broken stone aggregates bound together by stone dust or screening material and water applied during construction and compacted by heavy smoothed wheel roller.

What are the uses and limitations of WBM roads?

These roads are only suitable for slow moving iron wheeled traffic such as tongas, bullock carts etc. Constant use of road by iron wheels, the road metal gets crushed. Considering these factors, it may be inferred that a W.B.M road survives only for a short time.

What is GSB road?

Granular Sub-base (GSB) consists of laying and compacting well graded material on prepared sub-grade in accordance with the specifications.: GSB layer is intermediate layer in between Sub-grade and Wet mix macadam. GSB layer is laid in roads and higway works due to its properties .

What is PQC in road construction?

Pavement Quality Concrete (PQC) is normally employed for providing a strong surface of rigid pavements. PQC is also used for construction of runways in airports in order to distribute the heavy impact load from wheel to sub- grade layers [1].

What is GSB and WMM?

WMM = Wet Mix Macadam (40 mm down aggregates, mix design required) GSB = Granular Sub Base (63 - 40 mm aggregate or 70mm down aggregates) SR = Soil Replacement (preferably quary materials)

Which is better Wmm or WBM?

The WMM roads are said to be more durable. The WMM roads get dry fast and can be opened for traffic within less time as compared to the WBM roads, which take about one month for getting dry. WMM roads are soon-ready to be blacktopped with the Bituminous layers. WMM roads are constructed at a faster rate.

What is subgrade in road construction?

In transport engineering, subgrade is the native material underneath a constructed road, pavement or railway track (US: railroad track). It is also called formation level.

Is WBM a flexible pavement?

W.B.M is one type of flexible pavement. When a fast moving vehicle passes over a W.B.M road, the slurry of Murom is sucked out by the pneumatic wheel tires. The stone pieces get disturbed and finally the road surface is disintegrated. Thus the W.B.M roads are not suitable for fast moving vehicles with the wheel Tires.

What is the full form of CC road?

Road having their wearing surface consisting of cement concrete slab are called as cement concrete road. Cement concrete roads are considered as most serviceable and rigid pavements.

Why is it called water bound macadam?

Water bound macadam roads: The roads whose wearing course consist of clean crushed aggregates, mechanically interlocked by rolling and bound together with filler material and water and laid on a well compacted base course, is called water bound macadam road.

What is G1 G2 G3 in road construction?

G1, G2, and G3 are the aggregate gradations ranging from the most porous to the least porous, respectively. Properties of SFP include its volumetric properties, quality, and durability.

What is WMM material?

Wet Mix Macadam(WMM) work includes laying and compacting clean, crushed, graded aggregate and granular material, premixed with water, to a dense mass on a prepared GSB layer or existing pavement as per the requirement of the project.

What is the minimum thickness used in bituminous macadam?

6. What is the minimum thickness used in bituminous macadam? Explanation: The pavement used in bituminous Macadam is usually of a thickness of 50mm and maximum is 100 mm. Explanation: The interface between the existing pavement and new pavement can be provided by using tack coat.

What is DLC in road construction?

Dry Lean Concrete (DLC) is an important part of modern rigid pavement. It is a plain concrete with a large ratio of aggregate to cement than conventional concrete and generally used as a base/sub base of rigid pavement.

What is minimum thickness of GSB?

➢The recommended minimum thickness of granular base is 225 mm for traffic upto 2 msa and 250 mm for traffic exceeding 2 msa.

What is the thickness of WBM road?

Total number of layers and thickness of WBM road depends upon the details of design pavement. In general for ordinary roads, single layer of compacted thickness 75 mm may be sufficient. For special roads, 2 layers of 150 mm each compacted thickness may be provided.

What is the ratio of GSB?

GSB material is a mix of sand & gravels, crushed stone & broken rock. GSB material typically contain crushed stone > 50%. Material having CBR > 30% & PI < 6%. Water absorption < 2% & Agg impact value (AIV) < 40%.