Cement Types

Type Use C3S C2S C3A C4AF Comments

I general 45-55 20-30 8-12 6-10 no limits on 4 principal components

II general/

mod sulfate resistance/

mod heat of hydration

III high early strength

IV low heat of hydration

V high sulfate resistance

New Performance-based Specification for

Portland Cements

ASTM C 1157 Standard Performance Specification for Hydraulic Cement

Type GU General use

Type HE High-early strength

Type MS Moderate sulfate resistance

Type HS High sulfate resistance

Type MH Moderate heat of hydration

Type LH Low heat of hydration

Option R Low reactivity with alkali-reactive aggregates

Other Cement Types

• Type IA, Type IIA, Type IIA

• Blended cements (e.g., Types IP, IS, ISM, IIP, IIS, etc)

• White portland cement

• Masonry cement

• Expansive cements

• Calcium aluminate cements

• Rapid setting cements

• Oil well cements

Microstructure

Solids

• C-S-H

• CH

• Ettringite

• Monosulfate hydrate

• Residual unhydrated cement

Voids

• Entrapped air (>1mm)

• Entrained air (75-500um

• Capillary pores (macro →

meso)

• Interlayer space (micropores)

Water

• Capillary water

• Adsorbed water

• Interlayer water

• Chemically combined water

Microstructure

Solids

Interfacial Transition Zone

The ITZ is the region 10-50um

wide around coarse aggregate;

characterized by:

• Higher local porosity

• Greater density of pre-

existing microcracks

• Larger CH crystals that tend

to be oriented and more prone

to cleavage.

WEAK link in concrete!

By tailoring the concrete mixture to reduce the influence of the

ITZ, strength, E, and impermeability are increased.

• lower w/c

• higher cement content

• use of SCMs

• smaller MSA

• reactive dolomitic aggregate

• lightweight aggregate

• extended moist curing

Interfacial Transition Zone