Roadbaserefers to the sub-layer material, and it is placed directly on top of the undisturbed soil so as to provide a foundation to support the top layer of the road.This is the main structural layer which actually has the load distributing properties and a good roadbase should resist the permanent deformation and also the fatigue cracking from repeated loadings. Building roads starts right from planning and here carefully choosing the materials for a good roadbase is very important. Now roadbase can be of different kinds. It consists of granular materials which are properly placed and compacted to form a stiff layer used in road construction. To ensure the adequate stiffness binding agents are usually added. A ‘modified' roadbase basically incorporate a small amount of a binding agent such as lime; a ‘stabilized' roadbase consist of a larger amount of binding agents such as cement, fly ash or slag, one at a time or in a combination.

When the roadbase materials are stabilized, they are always fed through a dedicated stabilization mixing plant or a pug mill. Within these plants, the material is fed into a mixing chamber and this is where water and binders are added in a set sequence. This is to allow uniform dispersion of moisture and the binding additives. The uniform mixing and distribution of the stabilizing binders is critical to the roadbase performance. The amounts of stabilizing binders added are based on either the percentage by weight or volume. Also, the road surface has two kinds of layers, a based course and the wearing course. Sometimes in very light traffic conditions only a single layer is present. Basiclly the purpose of it is not only to resist the abrasion by traffic, but to rapidly shed surface water also.

For the construction of the roadbase, the material usually consists of well graded stone and dust mix which is held together by bitumen. The base course macadam is also important as this provides ultimate endurance against wearing. We must have noticed fragmented roads here and there; this is largely due to the incorrect roadbase course being laid there. For the smooth and strong road surface it is imperative to lay the correct roadbase. In America, the most popular material used in construction of roads is fiber.

Talking of road surface there are various aspects. Sometimes, Aggregate Base (AB) is made by mixing different sizes of crushed rock together, for building a road. An aggregate is normally made from quarried rock or it is sometimes made from recycled asphalt concrete or Portland cement concrete. Also the broken stone or cinders used in the construction or repair of roads material used in construction of roads is often called as road metal. Apart from this there are various types of road surfaces being built depending upon the requirements but the roadbases are usually more or less the same.The different types of road surfaces are asphalt, concrete and composite etc.

While making the roadbases various compliances have to be followed. Its strength and quality is not measured by the percentage of binder is added to the material but by testing the unconfined compressive strength (UGS). It includes the compaction of stabilised roadbase at the proper moisture content, curing and crushing under the controlled conditions, to test the compressive strength of the material.

It is also important for the roadbase material to be properly supplied by the supplier. Hence one should explain the requirements to him clearly. If there is a slight discrepancy, in the percentage of materials added in the mix meant for building the roadbase, the quality and thus the end product may get affected. So for building the best quality roads it is important to build the best roadbase because it determines the overall quality of road and its sustainability in long run.