Building Design and Construction Handbook - Merritt - Ventech!

4.4 SECTION FOUR
TABLE 4.1 Chemical and Physical Requirements for Portland Cement*
Type:
Name:
I and IA
Generalpurpose
II and IIA
Modified
III and IIIA
High
early
IV
Lowheat
V
Sulfateresisting
C3S, max % 35
C2S, min % 40
C3A, max % 8 15 7 5
SiO2, min % 20
Al2O3, max % 6
Fe2O3, max % 6 6.5
MgO, max % 6 6 6 6 6
SO3, max %:
When C3A � 8% 3 3 3.5 2.3 2.3
When C3A � 8% 3.5 4.5
C4AF � 2(C3A), max % 25
Fineness, specific surface, m2 /kg 160 160 160 160
Average min, by turbidimeter
Average min, by air
permeability test
Compressive strength, psi, mortar
cubes of 1 part cement and 2.75
parts graded standard sand after:
280 280 280 280
1 day min
Standard
1800
Air-entraining 1450
3 days min
Standard
1800 1500 3500 1200
Air-entraining 1450 1200 2800
7 days min
2800 2500 1000 2200
Standard
Air-entraining 2250 2000
28 days min
Standard
2500 3000
* Based on requirements in ‘‘Standard Specification for Portland Cement,’’ ASTM C150. See current
edition of C150 for exceptions, alternatives, and changes in requirements.
of the cement. Type III cement, however, has high heat evolution and therefore
should not be used in large masses. Because of the higher C 3A content, Type III
cement also has poor sulfate resistance. Type III cement is not always available
from building materials dealers’ stocks but may be obtained by them from the
cement manufacturer on short notice. Ready-mix concrete suppliers generally do
not stock Type III cement because its shorter set time makes it more volatile to
transport and discharge, especially in hot weather.
Type IV is a low-heat cement that has been developed for mass concrete construction.
Normal Type I cement, if used in large masses that cannot lose heat by
radiation, will liberate enough heat during the hydration of the cement to raise the
temperature of the concrete as much as 50 or 60�F. This results in a relatively large
increase in dimensions while the concrete is still soft and plastic. Later, as the
concrete cools are hardening, shrinkage causes cracks to develop, weakening the