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Cement Comparisons
Are all Hydraulic Cements Created Equal?
A survey on characteristics of cements produced in the US and Canada
requested 2004 yearly average data for cements manufactured under
ASTM C150/AASHTO M 85 (portland cements), ASTM C595/AASHTO M 240
(blended hydraulic cements), ASTM C1157 (hydraulic cements), ASTM
C91 (masonry cements), ASTM C1328 (plastic (stucco) cements), and
ASTM C1329 (mortar cements). The characteristics of interest include
those required to meet the chemical and physical requirements of
the respective ASTM/AASHTO specifications. Out of all 123 cement
plants operating in the region, 92 plants responded–a return
rate of about 75%–with data on 363 cements. The 2004 data
on blended and hydraulic cements produced to meet ASTM C595 and
ASTM C1157 respectively indicate broadly similar performance to
portland cements in strength development and setting times.
Figure 1 summarizes ASTM C109 compressive strengths for portland
cements. Type III cements clearly do have the highest early strength,
averaging about 25 MPa (3630 psi) at 1 day and 49 MPa (7150 psi)
at 28 days. Type I cements (for general use) average about 16 MPa
(2290 psi) at 1 day and about 41 MPa (5990 psi) by 28 days. Type
II cements (for moderate sulfate resistance) average slightly lower
1-day strengths, about 15 MPa (2160 psi), but by 28 days, provide
a slightly higher strength of about 43 MPa (6220 psi). Type V cements
(for high sulfate resistance) have the lowest average 1-day compressive
strengths, about 13 MPa (1860 psi) and by 28 days provide slightly
higher strengths than Type I or II cements, averaging almost 44
MPa (6320 psi).
(Click on graphs for larger images.)
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(c) |
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| Figure 1. ASTM
C109 compressive strengths of ASTM C150 portland cements as
reported in a 2004 survey: (a) About 52 Type I cements, (b)
about 79 Type II (including Type I/II) cements, (c) about 57
Type III cements, and (d) about 26 Type V cements. Blue circles
are mean values at 1-, 3-, 7-, and 28-days and gray bands indicate
the ranges of values reported. Numbers of cements are approximate
as data at all ages is not determined for all cements. |
Figure 2 shows data on 1-, 3-, 7-, and 28-day compressive strengths,
respectively, for ASTM C150 Type II (including Type I/II) portland
cements, ASTM C595 blended cements (Types IP, IS, I(PM) and I(SM))
and C1157 cements. All of these cements are intended for use in
general concrete construction. Although the average 1-day strength
of C595 cements is slightly lower than the average for Type II and
Type GU cements, nearly all of these cements fall into a range of
between 10 MPa and 20 MPa (1450 psi and 2900 psi) at 1 day. Likewise,
all of these cements at 3- and 7-days are in similar ranges, with
most falling into the 20 MPa to 30 MPa (2900 psi and 4350 psi) and
30 MPa to 40 MPa (4350 psi 5800 psi) ranges at these two ages respectively.
By 28 days, the C595 and C1157 cements have slightly higher strengths
on average (means all within 4%), and nearly all cements fall into
a range of between 35 MPa and 50 MPa (5080 psi and 7250 psi). This
result may not be surprising, since blended cements must compete
with portland cements and strength is generally an important market
consideration.
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(a) |
(b) |
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(c) |
(d) |
| Figure 2. ASTM
C109 compressive strengths of ASTM C150 portland cements (Type
II, including Type I/II), ASTM C595 blended cements (Type I(PM),
I(SM), and IP, and IS) and ASTM C1157 cements (Type GU), as
collected in a 2004 survey. Each column represents a single
cement. |
Figure 3 provides information on initial and final setting times
as determined by ASTM C191 (Vicat method). A few cements show atypical
setting times and may in fact be statistical outliers or may represent
somewhat specialized products designed for particular applications
(such as cement with long setting times for use in concreting in
hot weather). Generally, initial setting times fall between 80 minutes
and 160 minutes and final setting times fall between 175 minutes
and 275 minutes.
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(a) |
(b) |
| Figure 3. (a)
Initial and (b) final setting time (Vicat) of portland cements
(Type II), blended cements (Type I(PM), I(SM), and IP, and IS)
and ASTM C1157 cements (Type GU), as collected in the 2004 survey. |
Although all of these cements might not be created equally, the
range of compressive strengths and setting times for hydraulic cements
for general use are comparable. For more information on physical
and chemical properties of these cements, see PCA R&D
Serial No. 2879 for a free download with more detailed information.
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