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8/13/2019 Maturity Slides by Carino
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The Maturity Method: A Simple
Approach for EstimatingEarly-Age Strength
Development of Concrete
Dr. Nicholas J. Carino
Consultant
International Symposium on
Advances in Concrete TechnologyJanuary 9-13, 2012
Quito, Ecuador
Strength of Concrete Time
Temperature
Strength
Age
High T
LowT
S
S
t
8/13/2019 Maturity Slides by Carino
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Maturity Method
Technique to account for the combinedeffects of time and temperature onstrength development of concrete
Can be used to estimate in-place strengthat any time during constructionNeed to measure in-place temperature
Need the strength-maturity relationship ofthe concrete
Origins
Need for a technique to estimate strengthdevelopment under steam curing
McIntosh, J. D., 1949, Electrical Curing ofConcrete, Magazine of Concrete Research,Vol. 1, No. 1, January, pp. 21-28.
Nurse, R. W., 1949, Steam Curing ofConcrete, Magazine of Concrete Research,
Vol. l, No. 2, pp. 79-88. Saul, A. G. A., 1951, Principles Underlying the
Steam Curing of Concrete at AtmosphericPressure, Magazine of Concrete Research,Vol. 2, No. 6, March, pp. 127-140.
8/13/2019 Maturity Slides by Carino
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Maturity Rule
"Concrete of the same mix at the samematurity (reckoned in temperature-time)has approximately the same strengthwhatever combination of temperatureand time go to make up that maturity."
A.G.A. Saul, 1951
Maturity Rule Samples of the same concrete with same maturity
have same strength
Strength
Maturity Index, M
StrengthMaturityRelationship
Temp
erature
Time
To
M
Hot
Temp
erature
Time
To
M
Cold
M
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Maturity MethodASTM C1074
Developed in 1987
TerminologyASTM C 1074
Maturity
Maturity method
Maturity index
Maturity function
Strength-maturity relationship
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Terminology
Maturity
The extent of the development of aproperty of a cementitious mixture.
Note: At any age, maturity depends onthe curing history (time and temperature)
Terminology
Maturity method
Technique to estimate concrete strengthbased on the assumption that samples ofthe same concrete have equal strengthsif they have equal values of the maturity
index
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Terminology
Maturity indexAn indicator of maturity calculated from themeasured temperature history using a maturityfunction.(Note: The calculated index is indicative of maturityprovided there has been sufficient moisture forhydration during the time used in the calculation.)
Two indexes are used:
Temperature-time factorEquivalent age
Terminology
Maturity function
A mathematical expression that uses the measuredtemperature history during the curing period tocalculate a maturity index that is indicative of thematurity at the end of that period.
Nurse-Saul function (for temp-time factor) Arhennius function (for equivalent age)
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Maturity Functions
Nurse-Saul Function Temperature-time factor:
Arrhenius Equation Equivalent Age:
tTTtM a )()( 0
tet raTT
Q
e
11
Ta = Avg. concrete temperatureT0 = Datum temperature
Q = Temperature sensitivity factorTr = Reference temperature (in K)
Test smart Build right
Temperature-time FactorNurse-Saul Function
Time
ConcreteTemp.
To t
Ta
tTTtM a )()( 0
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Equivalent Age, teThe number of days or hours of curing at areference curing temperature (Tr) required toproduce a maturity equal to the maturityachieved by a curing period (t) at anothertemperature (T):
te = (T) t
(T) = Age conversion factor
1 1
( ) a rQ
T TT e
Test smart Build right
Effect of Q-Value on (T)Tr = 23 C (296 K)
0
1
2
3
4
5
6
0 10 20 30 40 50
Q = 4000 K
Q = 5000 K
Q = 6000 K
AgeConversionFactor
Temperature,oC
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Courtesy of TxDOT
Maturity Meters
Maturity Index Temperature-Time
Factor
Equivalent Age
Test smart Build right
Modern Maturity Meters
Sensor and data logger in oneembeddable unit
Maturity read by handheld readeror temperature data transferredto handheld computer
Or wireless data transfer
Courtesy of The Transtec Group
8/13/2019 Maturity Slides by Carino
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"COMA" Disposable Meter
Components
0
1
2
3
4
5days @
20 C
Cap
Capillary
Card
Plastic tube
Break Capillary
0
1
2
3
4
5days @
20 C
EquivalentAge @ 20C
Evaporation rate from capillary is affected by temperaturein the same way as strength development of concrete.
Test smart Build right
Break capillary Place tube intofresh concrete
Read concretematurity
Use of COMA Meter
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Implementation
ASTM C 1074
Permits maturity functions based on Nurse-Saul or Arrhenius equations
Procedure to establish strength-maturityrelationship
Procedure to estimate in-place strength
Annex for determining best value of To or Q
Terminology
Strength-maturity relationship
An empirical relationship betweencompressive (or flexural) strength andmaturity index obtained by testingspecimens whose temperature history up tothe time of test has been recorded.
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Strength-Maturity Relationship
Prepare cylinders (or cubes)
Embed temperature sensors at centerof two cylinders (or cubes)
Moist cure
At ages of 1, 3, 7, 14, and 28 d measurestrength and corresponding maturityindex
Plot average compressive strengthversus maturity index
Instrumented Specimen
Courtesy of TxDOT
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Strength-Maturity Relationship
Plowman:
Carino-Knudsen:
Freiesleben Hansen-Pederson:
)log(MbaS
)(1
)(
0
0
MMK
MMKSS
u
M
uS S e
Test smart Build right
Example of S-M Relationship
1000
2000
3000
4000
5000
6000
7000
10
15
20
25
30
35
40
45
0 4000 8000 12000 16000
S = -5942.1 + 2947log(M)R= 0.98208
CompressiveStrength,psi
Temperature-Time Factor, (oC-h)
Compres
siveStrength,
MPa
1 d
3d
7 d
14 d28 d
Best-ft Equation:
Plowman Logarithmic Equation
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Test smart Build right
Example of S-M Relationship
Plowman Logarithmic Equation
1000
2000
3000
4000
5000
6000
7000
10
15
20
25
30
35
40
45
100 1000 10000 100000
y = -5942.1 + 2947log(x)
R= 0.98208
Com
pressiveStrength,psi
Temperature-Time Factor, (oC-h)
Com
pressiveStrength,
MPa
1 d
3d
7 d 14 d
28 d
Best-ft Equation:
Estimating In-place Strength
Secure sensors to reinforcement or embedsensors into concrete a soon as practicable At critical locations in terms of exposure and
structural requirements
Connect sensors to maturity instruments
Read maturity index
Estimate strength from strength-maturityrelationship
8/13/2019 Maturity Slides by Carino
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Test smart Build right
Install Sensor
Courtesy of Con-Cure Corp.
Maturity
Meter
Test smart Build right
Courtesy of TxDOTCourtesy of Con-Cure Corp.
Read Meter
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1000
2000
3000
4000
5000
6000
7000
10
15
20
25
30
35
40
45
0 4000 8000 12000 16000
S = -5942.1 + 2947log(M)R= 0.98208
CompressiveStrength,psi
Temperature-Time Factor, (oC-h)
Co
mpressiveStrength,
MPa
1 d
3d
7 d
14 d28 d
Best-ft Equation:
Estimate Strength
Strength
Maturity Index
Summary
S
14.3
FieldMeasurement
MaturityMeter
MM
Laboratory Testing
7.2
MaturityMeter
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Limitations
Moisture must be available for hydration
Neglects effects of early-age temperature onlater-age strength
Only temperature is measured; need other teststo confirm concrete strength Early-age tests (ASTM C918) of standard-cured
specimens (from field): confirm strength potential
Pullout tests (ASTM C900): confirm in-place strength
Test instrumented specimens from field samples: verifyS-M relationship (Texas DOT Method Tex 426-A)
Maturity + Pullout Testing
Use the maturity method to determine whenthe required strength should have beenachieved in the structure
Verify by using pullout tests to estimate in-place strength
Combination of maturity and pullout testing canlead to rapid and safe concrete construction
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Maturity Functions
Nurse-Saul Function Temperature-time factor:
Arrhenius Equation Equivalent Age:
tTTtM a )()( 0
tet raTT
Q
e
11
Ta = Avg. concrete temperatureT0 = Datum temperature
Q = Temperature sensitivity factorTr = Reference temperature (in K)
Procedure for To and Q
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Isothermal Strength Gain
Age
Strength
to
kTSu
1
Su
( )
1 ( )
T ou
T o
k t tS S
k t t
Rate Constant, kT
Age
Strength
kT Su
1 Curing at higherT increases kT
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Rate Constant vs. Temperature
Temperature
RateConstant
kT
To
Linear FunctionObtain To
( ) ( )ok T A T T
Rate Constant vs. Temperature
Temperature
RateConstant
kT
Arrhenius EquationObtain Q
273( )
Q
Tk T Ce
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ExampleLinear function
Carino & Tank, ACI Journal, Mar-April 1992
0.0
0.5
1.0
1.5
2.0
2.5
3.0
-10 0 10 20 30 40 50
Type IType I + FA
RateConstant,day-1
TemperatureoC
-5 C
11 C
w/cm = 0.45
0.0
0.5
1.0
1.5
2.0
2.5
3.0
-10 0 10 20 30 40 50
Type IType I + FA
Rate
Constant,day-1
TemperatureoC
ExampleArrhenius equation
Carino & Tank, ACI Journal, Mar-April 1992
Q = 7640 K
Q = 3610 K
w/cm = 0.45
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Summary
Maturity method is a simple technique forestimating in-place strength
Removal of formwork
Application of prestressing
Termination of cold-weather protection or curing
Open structure to service
Accuracy of estimated strength depends on :
Using appropriate maturity function (To, Q) Good control of batching operations
Recognize that maturity method:
Measures only temperature Additional confirmation about the in-place concrete
is needed before applying construction loads
Assumes that adequate moisture is present forhydration Proper curing is required
Does not account for effects of high early-agetemperature on later-age strength Develop S-M at higher curing temperature
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Muchas gracias!