What is granular sub-base?

The granular subbase forms the lowest (bottom) layer of the pavement structure, and acts as the principal foundation for the subsequent road profile, provides drainage for the pavement structure, and protects the structure from frost.

What is granular subgrade?

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 subbase and base?

Base may consist of unbound materials, such as gravel or crushed stone, or stabilized materials, such as asphalt-, cement- or lime-treated materials. The subbase course is typically a granular borrow that is placed between the base and subgrade. It can be constructed as either a treated or untreated layer.

What is granular base aggregate?

In a pavement structure, the granular base and subbase are compacted aggregate layers between the asphalt concrete or the Portland cement concrete pavement layers and the underlying subgrade material.

What is GSB made of?

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%.

What is the function of granular base course?

Explanation: Granular base course is sufficient to be provided in low volume roads and moderate traffic roads. For heavy traffic loads, high quality materials are required to be used as a base course. Lean cement concrete or dry lean concrete can be used in the heavy traffic roads. 7.

What is a sub base?

Designover 3 years ago. The sub-base is the main load-bearing layer of paving construction. A well-designed sub-base should evenly spread the load of traffic, whether pedestrian or vehicular, down to the sub-grade, also known as the formation level.

What is sub base used for?

The function of a subbase is to help prevent pumping of fine-grained, subgrade soils. Pumping, which leads to the loss of soil material beneath slab edges and joints, occurs when three factors exist in combination: pumpable soils, excess water under the pavement, and frequent heavy truck loads.

What material is sub base?

The subbase is the layer of aggregate material that lies immediately below the pavement and usually consists of crushed aggregate or gravel or recycled materials (see Section 6C-1 – Pavement Systems for more information).

What is sub base made of?

Sub-base material is produced by crushing either limestone or granite rock. The sub-base is designed to evenly spread the load on traffic bearing areas such as pavements and roads. Made up of a load-bearing layer of aggregate, the sub-base is laid on the sub-grade layer below.

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