Materials and General Requirements
The materials used in embankments, subgrades, earthen, shoulders, and miscellaneous backfills shall be soil, moorum, gravel, a mixture of these.
Clay having liquid limit exceeding 70 and plasticity index exceeding 45; shall be considered unsuitable for embankment.
Sub-grade and top 500mm portion of the embankment just below sub grade shall be non-expansive in nature.
Density requirements of embankment and subgrade materials
|S.No.||Type of Work||Maximum laboratory dry unit wt.|
|1||Embankments up to 3m height, not subjected to extensive flooding.||Not less than 15.2kN/m3|
|2||Embankments exceeding 3m height or embankments of any height subject to long periods of inundation||Not less than 16.0kN/m3|
|3||Subgrade and earthen shoulders/verges/backfill||Not less than 17.5kN/m3|
When necessary, the original ground shall be levelled to facilitate placement of first layer of embankment, Scarified, mixed with water and then compacted by rolling so as to achieve minimum dry density.
The embankment and subgrade material shall be spread in layers of uniform thickness not exceeding 200mm by mechanical means, finished by a motor grader and compacted.
Clods or hard lumps of earth shall be broken to have a maximum size of 75mm when being placed in the embankment and a maximum size of 50mm when being placed in the subgrade.
Construction of Granular Sub-Bases
This work shall consist of laying and compacting well graded material o prepared subgrade.
The material shall be laid in one or more layers as sub-base or lower sub-base and upper sub-base.
The water absorption value of the coarse aggregate if is greater than 2%, the soundness test shall be carried out.
This work shall consist of clean, crushed aggregates mechanically interlocked by rolling and bounding together with screening, binding material where necessary and water laid on a properly prepared sub-base/subgrade/base or existing pavement, as the case may be and finished.
Wet-Mix Macadam Sub-Base
This work shall consist of laying and compacting clean, crushed, graded aggregate and granular material, premixed with water, to a dense mass on a prepared subgrade/sub-base/base or existing pavement.
The material shall be laid in one layer or more as necessary to lines, grades and cross-sections.
The thickness of a single compacted Wet-Mix Macadam layer shall not be less than 75mm.
When vibrating or other approved types of compacting equipment are used, the compacted depth of a single layer of the sub-base course may be increased to 200mm.
Preparation of Base and Surface Courses (Bituminous)
This work shall consist of preparing an existing granular or black-topped surface to specified lines, grades and cross-section in advance of laying a bituminous course.
The work shall consist of scarifying and re-laying the granular base course or scarifying the existing surface, filling of potholes, sealing of cracks and application of a profile corrective course as necessary.
Prime Coat over Granular Base
This work shall consist of application of single cost of low viscosity liquid bituminous material to an absorbent granular surface preparatory to any superimposed bituminous treatment or construction. Objective is to ping in the capillary voids of the porous surface and to bend the loose material particles on existing surface using a binder of low viscosity which can penetrate into voids.
This work shall consist of application of a single coat of low viscosity liquid bituminous material to an existing road surface which is relatively impervious preparatory to another bituminous construction over it.
The work shall consist of construction, in a single course, of compacted crushed aggregates premixed with a bituminous binder, to serve as base/binder course, laid immediately after mixing, on a base prepared previously.
This work shall consist of the application of one coat or two coats of surface dressing, each coat consisting of a layer of bituminous binder sprayed on the base prepared previously, followed by a cover of stone shipping properly rolled to form a wearing course.
You May Also Like-
Important questions on Bituminous Materials
Important Question on Tar (Highway Material)
Traffic Studies- Traffic Volume Study & Speed Study
Grade Separated Structures
WATER BOUND MACADAM BITUMINOUS ROAD
The term ‘soil’ in soil engineering is defined as an unconsolidated material, composed of solid particles, produced by the disintegration of rocks. The void space between the particles may contain air, water or both. The soil particles may contain organic matter.
What are Bricks? Bricks are one of the oldest building materials and it’s extensively used at present as a loading material in construction methods because of its durability, strength, reliability, low cost, easy availability, etc. Bricks are manufactured by molding burnt clay or a mixture of sand and lime or of Portland cement concrete, in…
Water Proofing Materials Dampness in a building is the main cause of the deterioration of the building as well as for the ill-health of the occupants. The damp brickwork in the buildings is prone to fresh attack. Also, the soluble salts in bricks are liable to attack the cement mortar when the brickwork remains wet…
Sound Insulation A well-designed building should incorporate sound insulation to restrain the noise level. High noise conditions result in uncomfortable living conditions, mental strains, fatigue, and may even lead to a nervous breakdown or temporary deafness. Adequate insulation can be achieved by using sound-absorbing or sound repellent materials. Sound Insulating Materials Sound Insulating Materials fall…
Heat Insulating Materials The purpose of thermal insulation is to restrict the heat transfer from warmer to cooler areas. Transfer of heat takes place by three processes- the convection, the radiation and, the conduction. Convection In convection, heat is transferred from one place to another by the movement and mixing of liquids or gases. Radiation…