Supplementary cementitious materials

1
Supplementary cementitious materials

• Definition
• Usually waste materials with similar chemistry to
  cement that react with the calcium hydroxide in
  the presence of water to form calcium silicate
  hydrate
• Australian Standards
• AS 3582 1998
• Part 1 Fly ash (FA)
• Part 2 Ground granulated blast-furnace slag
  (GGBS)
• Part 3 Silica fume (SF)

2
Supplementary cementitious materials

• Little or no cementing properties on their own.
• Reacts with lime in the presence of water to form
  cementitious compounds.
• Advantages
• cheaper that Portland cement
• slows hydration and heat evolution
• mass concrete
• improves workability
• reduce segregation and bleeding

3
Pozzolanic materials

• Fly ash
• coal fired power stations
• reduces permeability substantially
• Improves resistance to sulphate attack
• Improves resistance to chloride attack
• marine structures

4
Pozzolanic materials

• Fly ash

5
Pozzolanic materials

• Silica fume
• by product of silicon manufacture
• superfine material - has to be well dispersed to
  be effective
• used with a superplasticizer admixture
• reduction in permeability
• increase in durability
• low electrical conductivity
• greater resistance to steel corrosion
• almost complete suppression of bleeding
• high strength concrete (gt100MPa)

6
Pozzolanic materials

• Granulated blast furnace slag
• Obtained by quenching slag from blast-furnace
  during iron manufacture
• has limited hydraulic properties
• reduced strength at 28 days
• slower strength development
• resistant to chemical attack

7
Pozzolanic materials

• Granulated blast furnace slag