TYPES OF PAVEMENT: Pavement design consist of determining pavement thickness or the thickness of individual layer of pavement, in order to serve traffic for an anticipated design period based upon various factors like wheel load temperature etc. Commonly there are three types of pavements: 1. FLEXIBLE PAVEMENT 2. RIGID PAVEMENT 3. COMPOSITE PAVEMENT FUNCTIONS OF PAVEMENT: * To provide a smooth, strong, and adequately skid resistant riding surface with low noise deduction in all seasons. * They distribute traffic wheel load safely over a large area of sub grade, so that the stresses and strains are kept within allowable limits. BITIMINOUS C.C ROAD -------------------------------
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PAVEMENT DESIGN
Types of pavements: Based on the type of material used for construction pavement are classified into three types. 1. Flexible pavement:
SURFACE COURSE
SURFACE COURSE
BASE(GRANULAR)
BITMUNIOUS BASE
SUB BASE GRANULAR
SURFACE GRADE
SUB GRADE
FULL DEPTH BITUMINOUS PAVEMENT
BITMUNIOUS PAVEMENT
SURFACE COURSE
SUB BASE GRANULAR
SUB GRADE
GRANULAR PAVEMENT
Rigid pavement: The surface course consist of A.C.C slab with or without reinforcement Under wheel loads the top and bottom sides of fibers in slabs experiences compression and tension stresses respectively.
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PAVEMENT DESIGN
SURFACE COURSE
SUB BASE GRANULAR
SUB GRADE
Sub base layer in rigid pavements are provided for the following reasons: To decrease deflections in slab with an accompany reduces tendency for pumping mud. Sub base layer is required if the plastic sub grade soil is susceptible to pumping and has a tendency to weaken severely on the presence of melting frost. Sub base layer should be provided with the sub grade tends to change its volume with wearing moist content. Composite pavements: in this the wearing course of pavement is constructed by spreading bugs or precast,rectangular cement concrete blocks,interlocking concrete block. A composite pavement consist of cement concrete or cement treated granular granular or bituminous layer. The following factors should be considered at the stage of construction of pavement Purpose of load Location ,natural ground condition Traffic intensity and growth rate Type of vehicle and design speed Nature of wheel load Local availability of materials Purposed frequency and maintenance Stage construction
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PAVEMENT DESIGN
Funds availability for initial stage and for regular post construction maintenance. FACTORS AFFECTING DESIGN OF PAVEMENT Material characteristics: pavement material consist of different types of sub grade soil,granular materials,bindus,bitumen,tar,cement etc. Physical and engineering properties for different materials used for constructing for any kind of pavement plays an important role in thickness design of pavement. Traffic volume:- According to Indian practice(IRC 9-1972) an average traffic volume per day is calculated from 7 days 24 hours traffic count, estimation of future traffic volume for a design period is calculated in terms of standard axles per year.
A : Estimated traffic volume P: present traffic volume from traffic count survey r: growth rate of traffic nc: N flexiable = 365 X TGF X A X VDF X LDF X