Water bound macadam road layers or foundation | WBM road specification | What are the components of WBM road?
Water bound macadam road layers or foundation: - Water bound macadam road foundation, also known as WBM, is a type of road construction technique that involves a mix of stone aggregates and fines in different layers to create a strong and durable surface. WBM road layers The foundation of a water bound macadam road is made up of several layers. 1. Sub-grade - The first layer is the sub-grade layer which is the natural soil or aggregate layer before any modification. Function - The sub-grade layer is the natural or prepared surface on which the pavement is constructed. Its primary function is to provide a stable and even surface for the pavement layers. 2. Sub-base - The second layer is the sub-base layer made up of graded aggregates in varying sizes, thicker in depth and laid to a specific level of compaction. Function - The sub-base layer, placed above the sub-grade, is primarily designed to improve the structural capacity of the pavement system. It helps in distributing the load