Pavement Materials

1.0 INTRODUCTION

1.1 General

In regard to material testing and investigations involving various pavement layers, a (1m x 1m) test pit was dug and the various pavement layers were taken out upto the subgrade level, namely

* Bituminous layer

* Base course

* Sub grade course

* Sub grade soil

The various layer materials were tested to identify the various causes of failure of pavements and to suggest the remedial measures for strengthening and improvement of the pavement under consideration.

The following pavement materials were tested.

1. Subgrade soil for CBR value, Liquid limit, plastic limit, Plasticity Index etc.

2. Bitumen for penetration, softening point etc.

3. Bitumen emulsions as per IS: 8887

All the above investigations and testing of various materials was done in laboratory premises of CENTRAL ROAD RESEARCH INSTITUTE (CRRI), NEW DELHI.

Pavement materials :-

Aggregates 

Important properties of aggregate and In pavement construction with stabilized soils, bituminous, ¬treated subbase material, asphalt base, binder and surface courses, and maintenance operations of surface treatments, seal coats, and patching, the aggregate represents from 90 to 97 percent by weight of the total paving material. For economy in such construction, there should be and generally is, primary use of locally available construction aggregates rather than importing aggregates from long distances.

Photo 1.1 Road aggregates

Aggregate materials are produced from rock quarries as manufactured stone or obtained from natural gravel or soil deposits. Metal are refining and energy-producing processes produce artificial aggregates as a by-product. Representa¬tive of these are blast-furnace slag, wet-bottom-furnace slag, cinders, and other slags resulting from extraction of metals from their ores. There is also a class of synthetic aggre¬gates produced by calcinations and partial fusion of raw soil and rock materials such as clay and shale. In the future it may be prudent both ecologically and ec020mically to use as aggregate reprocessed construction materials reclaimed from building and pavement demolition.

Bitumen

Bitumen is a mixture of organic liquids that are highly viscous, black, sticky, entirely soluble in carbon disulfide, and composed