PPT ON BLENDED CEMENTS FOR DURABLE CONCRETE STRUCTURES

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BLENDED CEMENTS FOR DURABLE CONCRETE STRUCTURES  Presentation Transcript

1.BLENDED CEMENTS FOR DURABLE CONCRETE STRUCTURES

2.Portland Pozzolana Cement (PPC)
               (Flyash content: 15-35%)

Portland Slag Cement (PSC)
       [Slag(g.g.b.s) content:25-70%]

         In Ready Mixed Concrete(RMC) plants,
         OPC and Flyash are being procured
        separately and mixed in the Batching
         and Mixing plants.
      
3.TYPICAL COMPOSITION OF OPC,PPC and PSC

4.BLENDED CEMENTS TO RESIST SULPHATE ATTACK

5.GOOD QUALITY FLYASH

6.GOOD QUALITY G.G.B.S
1.Fineness: Typically,about 3000 cm2/gm
  2.Manganese Oxide: Max.5.5%
  3.Magnesium Oxide:Max.17.0%
  4.Sulphide sulphur : Max. 2.0%
  5.Glass content     :  Min. 85%
  6.Insoluble Residue: Max.  5%

7.ADVANTAGES OF USING FLYASH IN CONCRETE
The spherical particles of flyash have
    ball-bearing effect in concrete.So,the
    workability of concrete is increased.
Otherwise,water content of concrete can
   be reduced.So,the permeability of concrete can be reduced.Also,the reaction
   product(C-S-H) fills the pores inside the
   concrete over of time.

8.The sulphate resistance of concrete is
    improved mainly because of removal of
    Calcium Hydroxide.
The ingress of Chloride (if any) from the
     environment into the concrete is also
     reduced,because of lower permeability
      of concrete.
The heat inside the concrete is also less,
   because the heat of hydration of PPC is less.

9.Because of denser microstructure of
  concrete,the movement of ions inside the concrete is restricted,and the alkalies of cement are not able to react with the reactive silica (if any) inside the concrete.
 Thus,the concrete is resistant to Alkali-
   Silica Reaction(ASR)(if any).Also,the alkali
    of flyash is not fully effective.Only about
   1/6 of the alkali of flyash is reactive.

10.ADVANTAGES OF USING GGBS IN CONCRETE
Similar to flyash,g.g.b.s has also beneficial
   effect in concrete.
Improved workability of concrete,denser
    microstructure,resistant to Sulphate-
    attack(if any), lower heat of hydration
   and lower permeability of concrete.
Also resistant to Alkali-Silica Reaction(if
   any).Only 50% of the alkali of g.g.b.s
   is potentially reactive.

11.USE OF PSC FOR M55 GRADE OF CONCRETE(Typical Mix Proportions)

12.Use of PSC when Cl is encountered along with SO3 IN Soil & Ground water

13.TYPICAL CONCRETE MIX PROPORTIONS(M40) with OPC &Slag

14.DELHI METRO UNDERGROUND STRUCTURES

15.PPC(with 30% flyash) for a Concrete Dam in Arunachal Pradesh

16.Concrete Mix

17.CONSTRUCTION OF 5 KM LONG SEWAGE DISPOSAL PIPE LINE UNDER THE SEA AT BANDRA(MUMBAI).

18.SALHUS HIGH BRIDGE NORWAY

19.KUALA LUMPUR CITY CENTRE

20.Selection of cement for the Euro Tunnel
Connecting France and U.K.
37 KM under sea
Designed for 120 years
High performance concrete used

21.TUNNEL LINING CONCRETE (57 Mpa strength)EURO TUNNEL
Low C3A cement was not recommended
In marine environment, C3A is important to trap chloride ions entering the concrete
       Similar recommendations exist in IS 456 in case chloride is encountered along with sulphates in soil or ground water:
OPC with 5 to 8% C3A  OR
Portland Slag cement with more than 50% slag

22.CAST- IN-PLACE CONCRETE

23.30 Mpa Concrete was used
Durability of this concrete was of more concern than the strength
Three blended cements were used

24.Types of blended Cements
51% OPC +25% SLAG+24% FLYASH
70% PSC(82% SLAG) + 30% FLYASH       FOR  RCC
72% PSC(82%SLAG) + 28%FLYASH  FOR UNREINFORCED CONCRETE