maturity.pdf

Myers, J.J., “The Use of Maturity Methods as a Quality Control Tool for High Performance
Concrete Bridge Decks,” PCI / FHWA / FIB International Symposium on High Performance
Concrete , September 25-27, 2000.
THE USE OF MATURITY METHOD AS A QUALITY CONTROL TOOL FOR
HIGH PERFORMANCE CONCRETE BRIDGE DECKS
John J. Myers, Ph.D., P.E.
Assistant Professor of Civil Engineering
The University of Missouri – Rolla
Center for Infrastructure Engineering Studies
Rolla, Missouri, U.S.A.
ABSTRACT
Concrete technology has continued to advance throughout the years in order to meet the demands
of designers and innovative structural systems. In recent years, the application of high
performance concrete (HPC) to highway structures has been observed. HPC bridges not only
incorporate members with generally low surface area to volume (SA/V) ratios, but also
incorporate high contributions of cementitious materials within the mix constituents. This higher
content of cementitious materials often results in higher temperature development during
hydration. To investigate the applicability of the maturity method for HPC bridge decks given
these concerns, six bridge decks were instrumented and monitored in Texas as part of two SHRP
sponsored HPC Bridge projects. The study included the investigation of five different mix
designs, four of which were designated as HPC. This paper presents the results of said study and
discusses the applicability of the use of the method as a quality control tool for HPC Bridge
decks.
INTRODUCTION
A common means of strength prediction is the maturity method. This method uses an
empirical base to relate the time-temperature profile of a particular mix design to its strength at
early-ages. The use of the maturity method provides a few advantages when compared to
conventional quality control specimens for strength verification. For one, the maturity method
can assess the quality of the concrete through monitoring of the time-temperature profile at a
more frequent interval than is feasible through actual concrete sampling and quality control /
quality assurance (QC/QA) test specimens. For this reason, the maturity method can result in a
tighter level of QC throughout a project. In addition, the method provides a documented history
on the concrete within the structure and an immediate on-site acceptance method when strength
criterion are satisfied resulting in an earlier operational state for the structure.
Description / Background of the Maturity Method
The hydration of cement is affected by two factors, namely time and the temperature of
hydration. Therefore, it follows that the strength gain of concrete is also largely controlled by
these two factors. Given the set of constituent materials and proportions, maturity is a function
of the concrete’s temperature history at a given time provided there is sufficient moisture present
for hydration to occur. This method requires the determination of a strength-maturity
relationship in the laboratory for the mix proportions and constituent materials to be used in the
field effectively. Once the strength-maturity relationship for a particular mix design has been

2
developed in the laboratory, the field application only requires monitoring of the temperature
history of the in-situ concrete. This maturity index obtained in the field can be translated into
strength using the strength-maturity relationship developed in the laboratory as a non-destructive
strength evaluation technique. Also known as the temperature-time factor, M, the Nurse-Saul
equation (Equation 1) was one of the earliest functions presented to define the maturity index
and is still widely used today.
å ∆
−
= t
T
T
M o )
( (Equation 1)
The temperature-time factor is the area
between the time–temperature profile and the
datum temperature as illustrated in Figure 1.
It assumes a linear relationship between the
rate constant and the temperature where T is
the average concrete temperature (°C) during
a time interval of interest, ∆t, and To is the
datum temperature (°C). Various datum
temperatures have been proposed since this
relationship was developed. Saul proposed -
10.5°C (13.1°F) as the datum temperature
while in North America -10°C (14°F) is most
often used [1]. Malhotra [2] presented several
constraints for the maturity method to be valid
as follows:
1. Initial concrete temperature is between 15.6 and 26.7°C (60 and 80°F).
2. Concrete is maintained in an environment that permits further hydration.
3. Maturity is represented by curing at normal temperatures between the ages of 3 and 28 days.
In 1956, Plowman [3] proposed Equation 2 for the strength-maturity relationship based
on the strength developments of concretes cured at constant temperatures. The maturity-strength
function, S, is stated in terms of the strength obtained at 28 days of curing at 17.8°C (64°F) using
a datum temperature of -17.2°C (11°F). The variables a and b are constants related linearly to
the strength at any age. Plowman stated that this function was valid for times up to at least one
year and curing temperatures below 38°C (100°F). In addition, he proposed values for the
constants a and b based on different strength classes of concrete.
)
(logM
b
a
S +
= (Equation 2)
Another maturity index, called the equivalent age, te, (Equation 3) was proposed as an
alternative to the temperature-time factor. Equivalent age can be defined as the age of the
concrete cured at a constant temperature that yields the same relative strength gain as under the
actual temperature history. The concept assumes an exponential relationship between the rate
constant and temperature based on the Arrhenius equation.
))
1
1
(
exp(
s
e
T
T
R
E
t −
å −
= (Equation 3)
where: E = activation energy;
R = gas constant;
Ts = standard temperature in Kelvin.
200
40
80
120
160
2 18
4 6 8 10 12 14 16
0
Temperature,
deg
F
Age, hrs.
MATURITY = Area under the
temperature profile
20
deg C = (5/9)(deg F -32)
Figure 1: Schematic Representation for the
Definition of the Maturity Method

3
In 1983, Carino [4] proposed a three-parameter model for the relative strength gain-
maturity relation as illustrated in Equation 4.
)]
(
1
/[
)
(
/ o
o
u M
M
A
M
M
S
S −
+
−
= (Equation 4)
where:
Su = limiting strength as maturity approaches infinity;
Mo = maturity value when rapid strength gain begins;
A = initial slope of the relative strength-maturity curve.
Applicability of the Maturity Method for High Performance Concrete
The applicability of the maturity method for HPC was investigated by Carino [6] in 1992.
Mortar cubes with w/cm ratios of 0.29 and 0.36 were cured under water at constant temperatures
of 7, 23, 40°C (44.6, 73.4, 104°F). The rate constant versus the curing temperature was
represented by an exponential equation and five different models were used to represent the
relative strength versus maturity relationship. The following was concluded:
1. The maturity method was applicable to determine the combined effect of time and
temperature on the strength development of mixtures with low w/cm ratios.
2. For the mixtures investigated, the linear hyperbolic model appeared to be the most suitable
one.
3. Results indicated that the limiting strengths of the low w/cm ratio mixtures did not decrease
in a consistent manner, as in conventional concretes, by increasing the curing temperature.
Further investigation on the applicability of the maturity method to HPC was conducted by
Cetin [7]. He concluded that the traditional maturity-strength relationship based on standard
cured cylinders did not appear to be representative of strengths of concretes subjected to
accelerated heat curing for HPC.
EXPERIMENTAL PROGRAM
HPC Bridge Project Description
As noted previously, six bridge decks were instrumented and monitored in Texas as part
of two SHRP sponsored HPC Bridge projects. A brief description of these two bridge projects is
presented.
Louetta Road Overpass (Houston, Texas). The Louetta Road Overpass on State
Highway 249 in Houston consists of two three-span highway structures. The project was let in
February 1994. All components, including precast beams, precast piers, precast deck panels, and
cast-in-place decks were constructed with HPC. The Texas U54 beam, a 1372-mm (54-in.) deep
open-top U-shaped cross-section, was used for all girders in the two structures. Girder design
concrete strengths were as high as 90.3 MPa (13,100 psi) and most girders incorporated the use
of 15-mm (0.6-in.) diameter prestressing strand. Span lengths range from 37.0 to 41.3-m (121.4
to 135.5-ft.) and girder spacing from 3.57 to 4.82-m (11.7 to 15.8-ft.). The deck system
consisted of a 95-mm (3.75-in.) thick RC deck cast over 89-mm (3.5-in.) thick stay-in-place
precast / prestressed panels. Construction was completed in May 1997.
North Concho River/U.S. 87/S.O.R.R. Overpass (San Angelo, Texas). The San Angelo
HPC project consists of a 290-m (951-ft.) long, 8-span HPC bridge adjacent to a 292-m (958-ft.)
long, 9-span bridge designed using normal concrete. The project was let in June 1995. Spans 1
through 5 of the Eastbound HPC bridge range from 39.9 to 47.9 m (131 to 157 ft.) in length and

4
were designed using 1372-mm (54-in.) deep AASHTO Type IV girders. These HPC girders
utilized 15-mm (0.6-in.) diameter strands and design concrete strengths up to 96.5 MPa (14,000
psi). The normal concrete Westbound bridge was also designed using AASHTO Type IV
girders, with span lengths up to 42.7-m (140-ft.). Design concrete strengths of up to 61 MPa
(8,900 psi) and 13-mm (0.5-in.) diameter strands were used in these girders. The deck system
consisted of an 89-mm (3.5-in.) thick RC deck cast over 102-mm (4-in.) thick stay-in-place
precast / prestressed panels. Construction was completed in January 1998.
Description of Mix Designs under Investigation
A total of six spans were instrumented to monitor concrete maturity development
between the two High Performance Concrete Bridge Projects as outlined in Table 1. These
included a total of five different concrete mix designs. One mix design was conventional normal
strength concrete (NSC) meeting the TxDOT specifications for a Class S mix design. Two
additional mix designs were enhanced for improved long-term durability performance and
designated Class S Modified high performance concrete (HPC). Finally, two high-strength
concrete mix designs were investigated. These mix designs were designated Class K (TxDOT
special concrete designation) high-strength/high performance concrete (HS/HPC).
Instrumentation of Cast-In-Place Decks
Three locations within the CIP decks were selected to investigate concrete maturity
development throughout this investigation
as illustrated in Figure 2. An additional
location for the Louetta Road Overpass
Bridge decks was selected between the U-
Beams at the pier line due to the more
massive section of cast-in-place concrete.
These locations were selected since they
were anticipated to generate the critical
temperature development within the deck
(min. & max.) during hydration of the
concrete. The thermocouple located above
the precast panel at the centerline of deck
Table 1: CIP Decks Instrumented for Concrete Maturity Monitoring
Bridge Project Span
Location
Casting
Date
Concrete Mix Design
Description
Louetta Road Overpass Span 3 NB 10-31-96 Class S Modified HPC
Louetta Road Overpass Span 2 SB 11-8-96 Class K HS/HPC
North Concho River Overpass Span 1 WB 12-3-96 Class S Modified HPC
North Concho River Overpass Span 6 WB 2-5-97 Class S NSC
North Concho River Overpass Span 1 EB 6-12-97 Class K HS/HPC
North Concho River Overpass Span 4 EB 7-23-97 Class K HS/HPC
NB = Northbound, SB = Southbound, WB = Westbound, EB = Eastbound
NSC = Normal Strength Concrete, HPC = High Performance Concrete,
HS/HPC = High Strength/High Performance Concrete
Cast-In-Place Deck Cross Section
Thermocouple Locations :
1. Thickened Slab at Curb
2. Centerline of Deck Steel
3. At Support Between Panels
AASHTO Type IV
or U-Beam
to maturity
system
to maturity
system
Spacing Varies
7-1/4” min.
to 8” max.
Precast Concrete
Cast-In-Place Concrete
Figure 2: Schematic Representation of Cast-In-Place
Deck Thermocouple Locations

5
steel was anticipated to generate the lowest hydration temperature due to the
reduced mass of concrete (increased SA/V ratio) and heat dissipation provided by the
precast panel. The thermocouple located
centered in the more massive section of
CIP concrete at the perimeter location was
anticipated to generate the highest
hydration temperature due to the increased
mass of concrete (lower SA/V ratio). The
third thermocouple was located between
panels to investigate the variation of heat
dissipation through the precast beams.
Figure 3 illustrates a fully instrumented
deck with thermocouples prior to
placement of concrete. Standard
commercially available shielded
thermocouple wire was selected for
monitoring of concrete temperature as illustrated in Figure 4.
The thermocouple wire was attached to the data acquisition system at the abutment or
pier cap. Concrete maturity was monitored by a commercially available data acquisition system.
In order to compare the relative strength gain of the cast-in-place decks using the maturity
method, all tests were conducted in accordance with ASTM C1074-93, Standard Practice for
Estimating Concrete Strength by the Maturity Method [8].
Laboratory mixes were conducted on the field mix designs with identical mixture
proportions and constituents to develop
the natural maturity curve (strength versus
temperature-time factor) for each of the
five different mix designs involved in this
investigation. Compressive strength was
evaluated by averaging the results for
three representative 100 mm x 200 mm (4
in. x 8 in.) cylinders at test ages of 1, 3, 7,
14, 28, and 56 days in accordance with
ASTM test method C39-94. The results
of the laboratory mixes and the natural
maturity curves are reported in the
following section along with the results of
the concrete CIP bridge decks.
LABORATORY BASELINE
MATURITY
Table 2 summarizes the concrete maturity results for the five different mix designs that
were selected for use in the CIP bridge decks. Specimens were moist cured upon stripping of the
molds at 20-23°C (68-73°F) in accordance with ASTM C1074-93 until test age. The mix design
constituents and proportions as well as the performance related test results of these mix designs
are reported in Appendix A. The Class K mix designs generated the higher maturity values as
Figure 3: Cast-In-Place Deck Instrumentation
Figure 4: Shielded Thermocouple Prior to Placement
of Deck Concrete

6
anticipated due to their increased hydration temperatures from the higher cementitious contents.
The Class S mix design developed higher maturity values initially (1-day) when compared to the
Class S Modified mix design (North Concho River Overpass) due to the higher relative cement
content. Each of these mix designs was identical except that the Class S Modified mix design
had 30 percent fly ash replacement. The fly ash replacement resulted in lower hydration
temperatures and strength gain during the first twenty-four hours, but greater later age strength
gain after 48 to 72 hours.
FIELD MEASUREMENTS / RESULTS
Louetta Road Overpass Maturity Investigation
Two decks were instrumented at the Louetta Road Overpass (LRO) to investigate the use
of the maturity method for HPC and HS/HPC bridge decks. Figure 5 illustrates the compressive
strength gain with time of the two bridge decks instrumented for the maturity investigation at the
Louetta Road Overpass. The improved strength gain characteristics of the southbound deck may
be attributed to the use of a HRWR and reduced w/cm ratio.
Louetta Road Overpass Northbound HPC CIP Deck. Figure 6 illustrates the concrete
hydration temperature development at four locations within the deck upon placement of concrete
for the northbound Class S Modified HPC deck. The more massive 184-mm (7.25-in.) thick
sections of CIP concrete,
including the thickened slab at the
pier cap support and perimeter
overhang for the guardrail,
attained the highest hydration
temperatures as anticipated. The
thin 95-mm (3.75-in.) CIP
concrete deck above the precast
panel attained the lowest
hydration temperature as
anticipated. It may be noted that
concrete was placed during mild
ambient conditions as shown in
Figure 6. Thus, the precast panels
and U-Beams were able to act as
Table 2: Temperature-Time Factor, degree C-days
for Field Mix Designs as Developed in the Laboratory
Temperature-Time Factor, degree C-days
Time Louetta Road Overpass North Concho River Overpass
Days Hours Class S
Modified
Class K Class S Class S
Modified
Class K
1 24 498 746 556 533 588
3 72 1420 2122 1542 1616 567
7 168 3232 4900 3499 3510 3476
14 336 6489 9765 6976 6860 6963
28 672 13125 17950 13480 12880 13775
56 344 26397 33695 26867 25057 27877
0
2000
4000
6000
8000
10000
12000
14000
0 14 28 42 56
Time, days
Compressive
Strength,
psi
Class S Modified HPC - With 28% Fly Ash (NB Cast 10-31-96)
Class K HS/HPC - With HRWR & 32% Fly Ash (SB Cast 11-8-96)
Required 28 day Strength
Southbound = 8,000 psi
Northbound = 4,000 psi
1 ksi = 6.895 MPa
Figure 5: Compressive Strength Gain with Time
of Louetta Road Overpass CIP Bridge Decks

7
a “heat sink” and dissipate heat related to concrete hydration quite effectively. As discussed
previously, controlling or maintaining lower hydration
temperatures during placement only improves the quality and later age strength gain of the
concrete.
The concrete maturity results for the Northbound CIP deck at 7, 14, and 28 days versus
the natural maturity curve for the
mix design are illustrated in Figure
7. Although the initial hydration
temperatures varied within the
deck during the first 24 hours after
the placement (Figure 6), a very
minor variation in maturity
development at the various
locations was noted. The maturity
variation between the 28-day
results from the bridge deck and
the natural maturity curve were 3.4
percent on the conservative side.
The use of the maturity method for
the Class S Modified HPC mix
design were within ± 10 percent
variation typically associated with
the maturity method.
Louetta Road Overpass Southbound HS/HPC CIP Deck. Figure 8 illustrates the
concrete hydration temperature
development at four locations
within the deck upon placement of
concrete for the Southbound Class
K HS/HPC deck. Similar to the
Northbound deck, the more
massive sections of CIP concrete
attained the highest hydration
temperatures while the thinner CIP
concrete attained the lowest
hydration temperature. The
Southbound deck was also placed
during mild ambient conditions as
shown in Figure 8. Thus, the
precast panels and U-Beams acted
as a “heat sink” and dissipated heat
related to concrete hydration quite effectively. The Southbound deck attained a significantly
higher maximum hydration temperature of 67°C (152.6°F) compared to the Northbound deck of
45°C (113°F) under very similar placement conditions (ambient temperature). The much higher
hydration temperature of the Southbound deck may be attributed to the much higher
cementitious content.
30
40
50
60
70
80
90
100
110
120
0 10 20 30 40 50
Time After Placement, hours
Concrete
Temperature,
deg
F
Thickened Deck at Pier Cap
Between Panels at Support
Centerline of Steel Above Panels
Centerline of Deck at Guardrail
Ambient Temperature
deg. C = (5/9)(deg. F - 32)
Figure 6: Concrete Hydration Temperature Development of
Class S Modified HPC LRO Northbound Span 3
0
10
20
30
40
50
60
70
0 5000 10000 15000 20000 25000 30000
Temperature-Time Factor, deg C-days
Compressive
Strength,
MPa
Louetta Class S Mod HPC Mix Design Laboratory Maturity Curve
Concrete Maturity of Concrete Bridge Deck (2 in.)
Concrete Maturity of Concrete Bridge Deck (4 in. at curb)
NB = 27.6 MPa (4,000 psi)
deg. F = (9/5)(deg. C) + 32
1 ksi = 6.895 MPa
1 inch = 27.4 mm
(# in.) - indicates location of thermocouple from bottom of deck
Maturity Variation = 3.4% (28 days)
Figure 7: Concrete Maturity CIP Deck Field Results - Class S
Modified HPC LRO Northbound Span 3

8
The concrete maturity results for the Northbound CIP deck at 7, 14, and 28 days versus
the natural maturity curve for the mix design are illustrated in Figure 7. Although the initial
hydration temperatures varied within the deck during the first 24 hours after the placement
(Figure 8), a very minor variation in maturity development at the various locations was noted.
The maturity variation between the 28-day results from the bridge deck and the natural maturity
curve were 4.1 percent on the conservative side. The use of the maturity method for the Class K
HS/HPC mix design were within ± 10 percent associated variation of the method even though
the initial concrete temperature exceeded 26.7°C (80°F), the maximum internal concrete
temperature proposed by previous researchers [2] for the maturity method to be valid.
20
40
60
80
100
120
140
160
0 10 20 30 40 50
Concrete
Temperature,
deg
F
Centerline of Deck at Guardrail
Ambient Temperature
deg. C = (5/9)(deg. F - 32)
Figure 8: Concrete Hydration Temperature Development of Class K HS/HPC
Louetta Road Overpass Southbound Span 2
0
20
40
60
80
100
120
0 5000 10000 15000 20000 25000 30000 35000
Compressive
Strength,
MPa
Louetta Class K HS/HPC Mix Design Laboratory Maturity Curve
Concrete Maturity of Concrete Bridge Deck (4 in. at curb)
SB = 55.2 MPa (8,000 psi)
deg. F = (9/5)(deg. C) + 32
1 ksi = 6.895 MPa
1 inch = 27.4 mm
Figure 9: Concrete Maturity CIP Deck Field Results - Class K HS/HPC
Louetta Road Overpass Southbound Span 2

9
North Concho River Overpass Maturity Investigation
Four decks were instrumented at the North Concho River Overpass (NCRO) to
investigate the use of the maturity method for HPC and HS/HPC bridge decks. Figure 10
illustrates the compressive strength
gain with time of the three
different mix designs selected for
use in the maturity investigation at
the North Concho River Overpass.
The improved strength gain
characteristics of the Class K
Eastbound deck may be attributed
to the use of a HRWR and reduced
w/cm ratio. The improved later
age strength gain of the Class S
Modified concrete may be
attributed to the ASTM Class C fly
ash replacement. Note the lower
initial strength gain (1 to 3 days)
when compared to the Class S
concrete without fly ash replacement. This may be attributed to the hydration characteristics of
the ASTM Class C fly ash.
North Concho River Overpass Westbound NSC CIP Deck. Figure 11 illustrates the
concrete hydration temperature development at three locations within the deck upon placement
of concrete for the Westbound
Class S NSC deck. Similar to the
Louetta Road Overpass Bridge, the
more massive sections of CIP
concrete attained the highest
hydration temperatures while the
thinner CIP concrete attained the
lowest hydration temperature. The
deck attained a maximum
hydration temperature of 30°C
(86°F). The concrete maturity
results for Span 6 of the
Westbound C.I.P. deck at 3, 7, 14,
and 28 days versus the natural
maturity curve for the mix design
are illustrated in Figure 12.
0
2000
4000
6000
8000
10000
12000
14000
0 14 28 42 56
Time, days
Compressive
Strength,
psi
Class S NSC - Without HRWR & Fly Ash (WB Cast 2-15-97)
Class S Modified HPC - With 30% Fly Ash (WB Cast 12-3-97)
Class K HS/HPC - With HRWR & 30% Fly Ash (EB Cast 6-12-97)
Westbound = 6,000 psi
Eastbound = 4,000 psi
1 ksi = 6.895 MPa
Figure 10: Compressive Strength Gain with Time
of NCRO CIP Bridge Decks
30
40
50
60
70
80
90
100
110
0 10 20 30 40 50
Concrete
Temperature,
deg
F
Ambient Temperature
deg. C = (5/9)(deg. F - 32)
Class S NSC NCRO Westbound Span 6

10
Although the initial hydration temperatures varied within the deck during the first 24 hours after
the placement (Figure 11), a very
minor variation in maturity
the natural maturity curve was 0.8
the Class S NSC mix design was
well within ± 10 percent variation
typically associated with the
maturity method.
North Concho River
Overpass Westbound HPC CIP Deck. Figure 13 illustrates the concrete hydration temperature
development at three locations within the deck upon placement of concrete for the Westbound
Class S Modified HPC deck. The deck attained a maximum hydration temperature of 34°C
(93.2°F). The concrete maturity results for Span 1 of the Westbound CIP deck at 7, 14, and 28
days versus the natural maturity curve for the mix design are illustrated in Figure 14.
0
10
20
30
40
50
60
0 5000 10000 15000 20000 25000 30000
Compressive
Strength,
MPa
San Angelo Class S NSC Mix Design Laboratory Maturity Curve
WB = 27.6 MPa (4,000 psi)
deg. F = (9/5)(deg. C) + 32
1 ksi = 6.895 MPa
1 inch = 27.4 mm
NSC NCRO Westbound Span 6
40
50
60
70
80
90
100
110
0 10 20 30 40 50
Concrete
Temperature,
deg
F
Ambient Temperature
deg. C = (5/9)(deg. F - 32)
Class S Modified HPC NCRO Westbound Span 1

11
Consistent with the other decks under investigation, a very minor variation in maturity
the natural maturity curve was 0.2
the Class S Modified HPC mix
design was well within ± 10
percent variation typically
associated with the maturity
method.
North Concho River Overpass Eastbound HS/HPC CIP Deck. Figures 15 and 16
illustrate the concrete hydration temperature development at three locations within the deck upon
placement of concrete for Spans 1
& 4 of the Westbound Class K
HS/HPC decks. Span 1 & 4 decks
attained a maximum hydration
temperature of 51°C (123.8°F) and
53°C (127.4°F) respectively.
Similar to the Louetta Road
Overpass, the precast panels and
AASHTO Type IV beams acted as
a “heat sink” and dissipated heat
related to concrete hydration
effectively. However, the
configuration and spacing of the
U-Beam appeared to dissipate heat
more efficiently than the
AASHTO Type IV under similar
casting conditions (ambient
temperature). Although it is difficult to conclude this without any uncertainty since the rate and
heat of hydration was undoubtedly influenced by the chemical admixtures, mineral admixtures,
and the type & fineness of the cement particles used in the mix design. It should be noted that a
similar dosage of retarder was used when casting these decks.
0
10
20
30
40
50
60
70
0 5000 10000 15000 20000 25000 30000
Compressive
Strength,
MPa
San Angelo Class S Mod HPC Mix Design Laboratory Maturity Curve
WB = 27.6 MPa (4,000 psi)
deg. F = (9/5)(deg. C) + 32
1 ksi = 6.895 MPa
1 inch = 27.4 mm
Modified HPC NCRO Westbound Span 1
70
80
90
100
110
120
130
140
0 10 20 30 40 50
Concrete
Temperature,
deg
F
Ambient Temperature
deg. C = (5/9)(deg. F - 32)
Class K HS/HPC NCRO Eastbound Span 1

12
The concrete maturity results for
the Eastbound CIP deck at 3, 7,
14, and 28 days versus the natural
maturity curve for the mix design
are illustrated in Figure 17. The
maturity variation between the
28-day results from the bridge
deck and the natural maturity
curve was 10.3 percent. While
this value may be considered
marginal in terms of acceptable
variation, clearly the maturity
method approach resulted in
satisfactory performance for the
HPC decks investigated if proper
temperature controls are
considered during placement of
concrete.
SUMMARY
The use of the maturity method for the Class K HS/HPC mix design was at the outer limit
of the standard variation of ± 10 percent typically associated with the accuracy of the method.
While both Class K decks that
were monitored far exceeded the
maximum peak hydration
temperature of 37.8°C (100°F)
recommended by Plowman [3] at
all locations in the deck, the
maturity method predicted the
concrete strength within acceptable
levels on the conservative side.
However, it should be noted that a
higher variation was associated
with the HS/HPC decks that
included the higher contents of
cementitious materials. The high
relative SA/V ratio for these CIP
decks compared to other structural
components undoubtedly allowed for sufficient heat dissipation to avoid mass concrete/excessive
hydration temperature effects. Based on the results of the five HPC CIP decks investigated
within this study, the use of the maturity method resulted in an acceptable range of variation
between predicted and actual strength. However, it should be stated that temperature control for
CIP decks is advised for placement temperatures of HPC. The current TxDOT specification [9]
for bridge decks states “The temperature of cast-in-place concrete in bridge slabs and top slabs
of direct traffic structures shall not exceed 29.4°C (85°F) when placed.” This requirement is
70
80
90
100
110
120
130
0 10 20 30 40 50
Concrete
Temperature,
deg
F
Ambient Temperature
deg. C = (5/9)(deg. F - 32)
Class K HS/HPC NCRO Eastbound Span 4
0
20
40
60
80
100
0 5000 10000 15000 20000 25000 30000
Compressive
Strength,
MPa
San Angelo Class K HS/HPC Mix Design Laboratory Maturity Curve
EB = 41.6 MPa (6,000 psi)
deg. F = (9/5)(deg. C) + 32
1 ksi = 6.895 MPa
1 inch = 27.4 mm
Figure 17: Concrete Maturity CIP Deck Field Results - Class
K HS/HPC NCRO Eastbound Spans 1 & 4

13
also recommended for all HPC decks since previous research studies have documented the
importance of temperature control relative to concrete quality. During hot weather concreting,
cooling material stockpiles, cooled mixing water, or ice replacement may be necessary to satisfy
temperature placement requirements. In the case of the North Concho River Overpass,
approximately 1/3 ice replacement was used for the Eastbound HS/HPC CIP decks to meet the
TxDOT specification placement temperature requirement. These decks were cast during the
summer months. All other decks cast for both bridges satisfied the TxDOT placement
temperature requirements without adjusting material temperatures.
Should the use of maturity method be used as a quality control verification tool for
strength development, modifications to project specifications are required. The specifications
should at a minimum address the development of the maturity curve, the frequency of testing, the
acceptance criteria if strength is not met, and any secondary QC/QA measures. The
specifications must require that the maturity curve for the mix design be re-established as mix
constituents or mix contents are modified by the concrete producer. The frequency of testing,
equivalent to the number of maturity monitoring locations in the structure, should at a minimum
meet the current sampling frequency specified. Due to the ease of thermocouple installation,
concrete maturity development may be monitored even more frequently than previously
specified, which would result in a tighter level of quality control. The specifications should also
address acceptance criteria such as cores if strength is not met. A limited number of
representative cylinders should be specified as a secondary quality control measure in the
author’s opinion. When not used to verify strength, these specimens may be used to periodically
correlate field-produced concrete with the natural maturity curve of the concrete.
ACKNOWLEDGEMENTS
The author wishes to thank the joint sponsors of this research project, The Federal
Highway Administration and The Texas Department of Transportation, for their support and
encouragement. In addition, the author would like to thank the contractors, Jascon, Inc. of
Uvalde, Texas and Williams Brothers Construction Company of Houston, Texas, for their
assistance, interest, and involvement in this research study. Further acknowledgement goes to
Ramon L. Carrasquillo and Ned H. Burns with the University of Texas at Austin and Shawn P.
Gross with Villanova University for their invaluable efforts in making reporting of these results
possible.
REFERENCES
1. Carino, N.J., “The Maturity Method: Theory and Application,” Cement, Concrete, and
Aggregates, CCAGDP, Vol. 6, No. 2, Winter 984, pp. 61-73.
2. Malhotra, V.M., “In-Place Evaluation of Concrete,” Journal of the Construction Division
C02, Proceedings, ASCE, Vol. 101, No. 2, June 1975, pp. 345-357.
3. Plowman, J.M., “Maturity and the Strength of Concrete,” Magazine of Concrete Research,
Vol. 8, March 1956, pp. 13-22.
4. Carino, N.J., Lew, H.S., Volz, C.K., “Early Age Temperature Effects on Concrete Strength
Prediction by the Maturity Method,” ACI Journal, Vol. 80, March-April 1983.
5. Mindness, S., Young, J.F., “Concrete,” Prentice Hall Inc., Englewood Cliffs, 1981.
6. Carino, N.J., Knab, L.I., Clifton, J.R., “Applicability of Maturity Method to HPC,” NISTIR
4819, National Institutes of Standards and Technology, May 1992, 64 pp.

14
7. Cetin, A., “Effect of Accelerated Heat Curing and Mix Characteristics on the Heat
Development and Mechanical Properties of High Performance Concrete,” The University of
Texas at Austin, Department of Civil Engineering, Dissertation, December 1995.
8. ASTM C1074-93, Standard Practice for Estimating Concrete Strength by the Maturity
Method, American Society for Testing and Materials, Annual Book 1994.
9. Texas Department of Transportation, “Standard Specifications for Construction and
Maintainance of Highways, Streets and Bridges,” TxDOT, March 1995.
APPENDIX A
Table A.1: Mix Properties for Louetta Road Overpass and
North Concho River Overpass Cast-In-Place Decks
Louetta
Class S Mod - HPC
NB CIP Deck
Louetta
Class K - HS/HPC
SB CIP Deck
NCRO
Class S - NSC
Span 6 & 7 - WB
NCRO
Class S Mod - HPC
Span 1 - WB
NCRO
Class K - HS/HPC
Span 1 - EB
Mix Proportions
Coarse Aggregate, Type
Quantity
Limestone ⊗
1-1/2” max.
ASTM Grade 4
1856 pcy
Limestone ⊗
1” max.
ASTM Grade 5
1811 pcy
River Gravel ⊗
1-1/4” max.
ASTM Grade 5
1858 pcy
River Gravel ⊗
1-1/4” max.
ASTM Grade 5
1858 pcy
River Gravel ⊗
1-1/4” max.
ASTM Grade 5
1978 pcy
Fine Aggregate, Type
Quantity
Natural River Sand
FM = 2.54
1243 pcy
Natural River Sand
FM = 2.54
1304 pcy
Natural River Sand
FM = 2.70
1307 pcy
Natural River Sand
FM = 2.70
1229 pcy
Natural River Sand
FM = 2.70
1127 pcy
Water, Type
Quantity
City of Victoria
Potable Water
230 pcy
City of Victoria
Potable Water
245 pcy
City of San Angelo
Potable Water
272.6 pcy
City of San Angelo
Potable Water
252.1 pcy
City of San Angelo
Potable Water
177.1 pcy
Cement, Type
Quantity
Type C-I
383 pcy
Type C-I
673 pcy
Type LS-II
609.4 pcy
Type LS-II
426.7 pcy
Type LS-II
489.4 pcy
Fly Ash, Type
Quantity
Percent by Weight
ASTM Class C
148 pcy
28%
ASTM Class C
221 pcy
32%
None
ASTM Class C
191 pcy
30%
ASTM Class C
211 pcy
30%
Retarder, Type
Quantity
ASTM Type B
45 oz/cy
ASTM Type B
22 oz/cy None None
ASTM Type B
28 oz/cy
HRWR, Type
Quantity
ASTM Type F
None
ASTM Type F
122 oz/cy None None
ASTM Type F
NR
Air Entrainment, Type
Quantity
ASTM C260
2.0 oz/cy None
ASTM C260
6.0 oz/cy
ASTM C260
5.0 oz/cy
ASTM C260
3.0 oz/cy
Fresh Concrete Properties
W/Cm (C+FA), by weight 0.43 0.27 0.45 0.41 0.25
Slump 3 to 4 inches 7 to 9 inches 3 inches 3.75 inches 8 inches
Total Air Content 5.0 % 1.4 % 6.0% 5.0% 4.6%
Unit Weight 143.2 pcf 150.2 pcf 145.6 pcf 145.3 pcf 149.3 pcf
Compressive Strengths
Design Strength (28-day) 4,000 psi 8,000 psi 4,000 psi 4,000 psi 6,000 psi
Actual 28-day Strength ⊕ 5,600 psi 9,630 psi 5,250 psi 7,100 psi 9,030 psi
⊗ Crushed Aggregate Source
⊕ ASTM Moist Cured Cylinders
1 lb/yd3
= 27 lb/ft
3
= 0.5933 kg/m
3
1 ksi = 1,000 psi = 6.895 MPa
1 oz/yd
3
= 0.03868 L/m
3
1 inch = 25.4 mm

maturity.pdf

More Related Content

Similar to maturity.pdf (20)

More from osamaanter1 (8)

Recently uploaded (20)

maturity.pdf