CONCRETE PAVEMENTS

DIFFERENCES BETWEEN CONCRETE AND ASPHALT PAVEMENT

DIFFERENCES BETWEEN CONCRETE AND ASPHALT PAVEMENT ContAsphalt pavement is flexible pavementConcrete pavement is rigid pavementIn both pavement load is distributed over subgradeMajor factor in rigid pavement is structural strength of concreteIn concrete pavement reinforcement, texture, colour can be providedAfter 10-15years asphalt pavement need rehabilitationAsphalt pavement is more susceptible to water

CONCRETE PAVEMENT FUNDAMENTALSConcrete pavement is becoming more versatile pavement.They may be designed for a life of 5,10,20,50 years.Each concrete pavement consist of important components:Transverse jointTie barDowel barSub baseSub gradeLongitudinal joint

JOINTED PLAIN CONCRETE PAVEMENTJointed Plain Concrete Pavement contain enough joints to control natural cracksJPCP do not contain any steel reinforcementSmooth steel bars at transverse joints and deformed steel bars at longitudinal jointsToday majority of the U.S state agencies build jointed plain pavement

CONCRETE PAVEMENT TYPES Concrete pavement is divided in to 3 typesJointed plainJointed reinforcedContinuously reinforcedEach type used to control crack developmentCrack development due to concrete shrinks, contracts and expandsCracking can be controlled by use of joints and reinforcing steel

JOINTED PLAIN CONCRETE PAVEMENT

JOINTED REINFORCED CONCRETE PAVEMENTJointed Reinforced Concrete Pavements contain steel mesh reinforcementIn JRCP designers increase the joint spacing purposely and include reinforcing steelThe spacing between transverse joints is typically 30 feet or moreToday only a handful of agencies employ this design

JOINTED REINFORCED CONCRETE PAVEMENT

CONTINUOUSLY REINFORCED CONCRETE PAVEMENTContinuously Reinforced Concrete Pavement does not require any transverse contraction jointsTransverse cracks are expected in the slab at intervals of 3 - 5 ftIn CRCP steel designed with 0.6 - 0.7 % by cross sectional area ,so the cracks are together tightly

CONTINUOUSLY REINFORCED CONCRETE PAVEMENT

JOINTSThere are three basic joint typesContractionConstructionIsolationImportant factor is load transfer to sub-base

CONTRACTION JOINTSThis joints are control crack from stresses caused by concrete shrinkage, thermal contraction, moistureTransverse contraction joints are cut at a right angle to the pavement centreline and edges

CONTRACTION JOINTS

CONSTRUCTION JOINTSConstruction joints join concrete is paved at different timesTransverse construction joints are necessary at the end of a paving segment, cross road or bridge

CONSTRUCTION JOINTS

ISOLATION JOINTSIsolation joints separate the pavement from structures or objects like manhole ,drainage fixtures, sidewalksThey allow independent movement of the pavement

ISOLATION JOINTS

CONCRETE PAVING BASICSThere are two basic methodsFixed-form pavingSlip-form pavingFixed-form paving requires the use wooden forms that are set up along the perimeter of the pavement before pavingSlip-form paving does not require any wooden forms

CONCRETE PAVING BASICS ContThere are a variety of different fixed form paving machinesThe least complex are vibratory screeds and revolving tubesThese hand-operated machines finish the surface of the pavement between fixed forms

ROLLER SCREED (REVOLVING TUBE) FOR FIXED-FORM PAVING ON A STREET

SLIP-FORMSlip-form paving is preferred by contractors for large paving areasIt can provide better productivity with less laborSome machines are also equipped with automatic finishing equipment and equipment to automatically insert dowel bars into the pavement at transverse joints

SINGLE-TRACK SLIP-FORM PAVER

SLIP-FORM ContWhile paving, slip-form paving machines are equipped with sensors to follow string-lines that are put into position along either side of the paving areaThe string-lines control the paver direction and surface elevationSmaller paving projects may use only the slip-form machine

SINGLE-TRACK SLIP-FORM PAVER

FAST-TRACK CONCRETE BASICSFast- track concrete mixtures develop strength rapidlyThey are beneficial when early opening of the pavement is necessaryMost often the concrete mixture components are specially proportioned and selected for rapid early strength