9/24/13

1

Roadway  and  Pavement  Design  

  Rigid    High  strength      Durable      Workable  

  Same  as  for  asphalt  surface  layers    Safe  (friction)    Durable  (long  lasting)    Comfortable  (smooth  ride,  quiet)  

9/24/13

2

  Strength  gain  with  time  requires:    Adequate  moisture    Sufficiently  high  temperature    Time  

7  days   28  days  

Air  

Moist  curing  room  

Streng

th  

7  days   28  days  

115  °F  

Streng

th  

40  °F  

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3

W/C  

Streng

th  

0.35   0.45   0.55  

Air  entrained  

Non-­‐air  entrained  

Time  or  Temperature  

Slum

p  (in

.)  

  Compressive  strength      Indirect  tensile  strength    Modulus  of  rupture    Fatigue  resistance  

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4

Load  (P)  

P    =  applied  load  

A    =  loaded  area    

Typically  4,000  to  6,000  psi  at  28  days  

6  in.  x  12  in.  Specimens  

fc' =

PA

indirect  tensile  load  (P)  

d  =  diameter  

t  =  thickness  

ft =2P!dt

ft = 5.7 fc'

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5

load  

load  

test  specimen  

stress  distribution  across  diametral  plane  

compression              tension  

150mm  

Reaction   Reaction  

Load   Load  Beam  Specimen  

Uniform  Bending    

Modulus  of  Rupture  (Flexure  Strength)  

M  =  Moment  c  =  distance  to  extreme  fiber  I  =  Moment  of  Inertia  

Sc =McI

Sc = 7.5 fc'

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6

  Same  test  setup  as  modulus  of  rupture    1  to  2  repetitions  per  second    Calculate  stress  ratio  

  No.  of  cylces/sc    55%  limit  

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7

  High  performance  concrete  (HPC)    Fiber  reinforced  concrete  (FRC)    Polymer  concrete    Roller  compacted  concrete    Ultra  thin  white  topping  (UTWT)  

  HPC    Strengths  >  6000psi  

  FRC    Controls  shrinkage  cracking  

  Polymer  concrete    Rapid  curing  repair  material  

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8

  Roller  compacted  concrete    Very  lean,  no  slump,  almost  dry  concrete  (logging  roads  and  freight  yards)  

   Ultra  thin  white  topping    Thin  highly  modified  PCC  overlay  material