The compaction value used depends on the requirements of the material being tested and for roadbase the value is normally, 100% of standard compaction but the moisture content will be somewhat less than OMC and mostly in the order of 85% of OMC.

Asphalt road surfaces are also considered a sustainable option for road paving material where bitumen is used as binder as this material can be recycled. The bitumen, produced by the refineries, plays an important role in road durability which is also important for sustainability.

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.

A wide variety of materials are used in the construction of roads these are soils (naturally occurring or processed), aggregates (fine aggregates or coarse aggregates obtained from rocks), binders like lime, bituminous materials, and cement, and miscellaneous materials used as admixtures for improved performance of …

Asphalt concrete

A typical flexible pavement structure (see Figure 2) consists of:

• Surface Course. The layer in contact with traffic loads.
• Base Course. The layer immediately beneath the surface course.
• Subbase Course. The layer between the base course and subgrade.

four layers

A subgrade is made up of native soil that has been compacted to withstand the loads above it. There is no consistency in regards to the terms of subbase and subgrade, but normally the subgrade is the native soil while the subbase is the layer of soil or aggregate on top of the subgrade.

The selection of the pavement and gravel thickness is based on three criteria (Figure 3): (1) the thickness of the asphalt pavement is 0.1 m and the gravel base thickness is 0.2 m, which is shortened to 10 to 20 types; (2) the thickness of the asphalt pavement is 0.18 m and the gravel base thickness is 0.2 m, which is …

The authors suggest the following computation method for obtaining pavement thickness using Gray’s formula: (1) carefully study the traffic mix likely to occur at a project site; (2) calculate the total load and radius of the contact area on the basis of the proportions of vehicle types; (3) add an extra impact factor …

6-12 inches

2” thick

The 60-70 grade is usually used only in pavements where traffic is very heavy such as principle city streets and very heavily trafficked rural highways. The second grade, 85-100, is by far the most widely used material for plant mixes and is suitable for most pavements.

Two inches

Several procedures can be used to calculate the thickness of the proposed asphalt pavement. All are based on the volume and weight of the traffic that will use the facility and on the load-supporting capability of the underlying soil.

➢The sub-base material should have minimum CBR of 20% for cumulative traffic up to 2 msa and 30% for traffic exceeding 2 msa. ➢The material should be tested for CBR at the dry density and moisture content expected in the field.

300mm

three types

Explanation: The design life of flexible pavement is considered as 15 years, it may last even further if properly maintained. Explanation: The design period of cement roads is usually taken as 30 years but they can even last longer if properly maintained and designed.

The California Bearing Ratio (CBR) test is a penetration test used to evaluate the subgrade strength of roads and pavements. The results of these tests are used with the curves to determine the thickness of pavement and its component layers. This is the most widely used method for the design of flexible pavement.

50mm

Polyester Overlays

Which bitumen does not need heating? Explanation: The cutback bitumen which is the most economical type may or may not require heating, whereas the remaining required to be heated.

Bituminus concrete is a mixture of stone aggregates and coarse sand with bitumen as the binding material. Whereas, Bitumen mecadam is a mixture of stone aggregate only binded with bitmen and has porisity but more compressive strength that’s why it is used as strengthening layer to increase the strength of the pavement.

2.2 Bituminous macadam (BM) shall consist of mineral aggregate and appropriate binder, mixed in a hot mix plant and laid with a mechanized paver. It is an open graded mixture suitable for base course. It is laid in a single course or in a multiple layers on a previously prepared base.

First of all i want to tell you that DBM act as bituminous base course while BC acts as wearing course. LAYING OF DBM(Dense Bituminous macadam) /BC(Bituminous concrete) Laying of DBM/BC is done with the help of paver.

CONSTRUCTION OF BITUMEN BOUND MACADAM FOR STRENGTHENING OF ROAD PAVEMENT. BBM is similar to WBM, except that key aggregates and bitumen are used as binder, instead of screenings and water. The BBM layer can conventionally be laid over an existing bitumen layer, after applying a tack coat.

The bending moment (BM) is the algebraic sum of the moments of the forces and reactions acting on one side of the section about the section. It can also be visualized as torque as it is also force multiplied by the distance from point of its application.

1- How can we calculate the required DBM/BC quantity? Length of DBM/BC layer (L) = 1 Km = 1000 Met. Breadth of DBM/BC Layer (B)= 5 Met. Thickness of DBM/BC Layer (T) = 50 mm =0.050 Met.

Method Statement For Laying of Binder Coarse (BC), Dense Bituminous Macadam (DBM), Bituminous Macadam (BM) for the main carriageway and Semi Dense Bituminous Macadam (SDBM) for the service roads.