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Prasad Rangaraju
Enamur Latifee
Sai Sudhir Reddy Enugula
Clemson University, SC
Considerations in Application of MCPT in Evaluating
ASR Potential of Job Concrete Mixtures
Advances in AAR Test Methods for Evaluation of Job Concrete Mixtures, Part I
Clemson University 2/36
Acknowledgements
o Federal Highway Administration
o Portland Cement Association
o Lehigh Cement
o ARGOS Cement
o Aggregate Suppliers
Clemson University 3/36
Overview
o Brief Review of Existing Test Methods for ASR
o Review of Mini Concrete Prism Test (MCPT)
o Field Concrete Factors that affect ASR Testing
o Experimental Investigation To Evaluate Role of
Specific Concrete Mixture Variables (Job Concrete)
on Expansion due to ASR
o Conclusions
Clemson University 4/36
Existing AAR Test Methods in ASTM
ASR
o ASTM C 227 – Mortar Bar Test
o ASTM C 289 – Quick Chemical Test
o ASTM C 295 – Petrographic Examination
o ASTM C 1260 – Accelerated Mortar Bar Test (AMBT)
o ASTM C 1293 – Concrete Prism Test (CPT)
ACR
o ASTM C 295 – Petrographic Examination
o ASTM C 586 – Rock Cylinder Test
o ASTM C 1105 – Concrete Prism Test
Clemson University 5/36
Miniature Concrete Prism Test
(AASHTO TP110)
o MCPT is developed based on modifications to CPT
and AMBT methods. The improvements over the
standard test methods are :
o No significant aggregate crushing is involved
o No alkali leaching
o Short test duration o 56 days (8 Weeks) for majority of aggregates
o 84 days (12 weeks) for slow reacting aggregates
o Can detect both ASR and ACR
o Can evaluate both aggregate reactivity and SCM
effectiveness
o Potential to evaluate job concrete mixtures
Clemson University 6/36
MCPT Method (AASHTO TP 110)
o Cement Content = 708 lb/yd3 (420 kg/m3)
o Cement Alkali Content = 0.9% ± 0.1% Na2Oeq.
o Alkali Boost, (Total Alkali Content) = 1.25% Na2Oeq.
o Water-to-cement ratio (fixed) = 0.45
o Coarse Agg. Dry-Rodded Vol. Frac. = 0.65 (MSA: ½ in.)
o Storage Environment* = 1N NaOH Solution
(Soak)
o Storage Temperature = 60⁰C
o Specimen Size = 2 in. x 2 in. x 11.75 in.
1 N NaOH @ 60ºC
Clemson University 7/36
MCPT Measurementso 1st Day = Water bath at 60 ⁰C
o Subsequent Storage = 1N NaOH @ 60⁰C
o Length Change Measurement = 1, 3, 7, 10, 14, 21, 28, 42,
56, 70, 84 days
o Non-reactive sand is used with reactive coarse agg, and vice-
versa.
Clemson University 8/36
MCPT Specimen Size
Clemson University 9/36
MCPT Validation
o Evaluated 33 aggregates with known field
performance
o Limited set of 12 aggregates were tested in
MCPT, CPT and AMBT for correlations
o Evaluated 20 different SCMs (fly ash, slag,
meta-kaolin, silica fume)
Clemson University 10/36
MCPT-56 day versus CPT – 365 day
Clemson University 11/36
MCPT-56 day versus AMBT – 14 day
Clemson University 12/36
Expansion Criteria for Classifying Aggregate Reactivity
(Latifee and Rangaraju, 2015)
Clemson University 13/36
Expansion Criteria for characterizing
effectiveness of ASR Mitigation measures (MCPT)
Clemson University 14/36
Multi-lab Testing of MCPT
Correlation between 56-Day % Exp. and COV
Mix 2 (Avg. Exp = 0.578%)
Mix 1 (Avg. Exp = 0.134%)
Mix 3 (Avg, Exp = 0.033%)
Mix 4 (Avg.Exp = 0.015%)
Clemson University 15/36
MCPT - AASHTO TP 110
o AASHTO has
approved this
method as a
provisional
standard
AASHTO TP 110
MCPT for Evaluating ASR
Potential of Job Mixtures
Clemson University 17/36
Influence of Job mix parameters on
ASR expansion
o Typical job mix parameters that differ from the standard MCPT
method were considered.
o Univariate analysis:
o Influence of w/c (0.40 – 0.50)
o Influence of total cement content (600 -800 lb/yd3)
o Influence of total alkali loading in concrete (2.9 – 10lb/yd3)
o Influence of dosage of SCM (15% - 35% Class F fly ash)
o Influence of vol. fraction of CA content in concrete (0.65 –
0.75)
o Influence of pore solution alkalinity
Clemson University 18/36
Effect of pore solution on the % expansion in the MPCT
o SHRP C-342 (Helmuth et.al. 1993) proposed the following:
o [OH-] = 0.339 Na2O % / (w/c) + 0.022 +/- 0.06 mol/L
0.000
0.040
0.080
0.120
0.160
0.200
0 7 14 21 28 35 42 49 56 63 70 77 84
Ex
pa
nsi
on
, %
Age, Days
HighAlk, boosted 1.25%, 1N sol
AC 0.82%, 0.7 N sol
AC 0.49%, 0.45N sol
R² = 0.895
R² = 0.9969
0.000
0.020
0.040
0.060
0.080
0.100
0.120
0.140
0.160
0.4 0.5 0.6 0.7 0.8 0.9 1 1.1%
Ex
pa
nsi
on
Soak Solution Alk., N NaOH
Expansion at 56-day
Expansion at 28-day
Clemson University 19/36
Effect of w/c ratio on the expansion of test
specimens with high- and low-alkali cement
0.000
0.040
0.080
0.120
0.160
0.200
0 7 14 21 28 35 42 49 56 63 70 77 84
Exp
an
sion
, %
Age, Days
0.50 w/c
0.45 w/c
0.40 w/c
0.000
0.040
0.080
0.120
0.160
0.200
0 7 14 21 28 35 42 49 56 63 70 77 84
Exp
an
sion
, %
Age, Days
0.50 w/c0.45 w/c0.40 w/c
0.1207 0.1230 0.1235
0.0287 0.03100.0375
0.000
0.020
0.040
0.060
0.080
0.100
0.120
0.140
0.160
0.180
0.200
0.40 w/c 0.45 w/c 0.50 w/c%
Exp
an
sion
at
56 d
ays
Water to Cement Ratio
High Alkali CementLow Alkali Cement
Cement Content = 708 lb/yd3
HA
LA
Clemson University 20/36
Effect of cement content on expansion in
MCPT with High and Low Alkali Cement
0.0000
0.0400
0.0800
0.1200
0.1600
0.2000
0 7 14 21 28 35 42 49 56 63 70 77 84
Exp
an
sion
, %
Age, Days
800 lbs/yd3
700lbs/yd3
600 lbs/yd3
0.0000
0.0400
0.0800
0.1200
0.1600
0.2000
0 7 14 21 28 35 42 49 56 63 70 77 84
Exp
an
sion
, %
Age, Days
800 lbs/yd3700lbs/yd3600 lbs/yd3
y = 0.0167x + 0.0843
R² = 0.9287
y = 0.0059x + 0.0202
R² = 0.9767
0.000
0.020
0.040
0.060
0.080
0.100
0.120
0.140
0.160
600 lb/yd3 700 lb/yd3 800 lb/yd3
% E
xp
an
sion
at
56
-day
Cement Content
High Alkali
Low Alkali
w/c =0.45
HA
LA
Clemson University 21/36
Effect of total alkali loading in concrete on
MCPT expansion
Cement Content,
lb/yd3
Total Alkali
Loading
(lb/yd3)
56-Day Expansion (%)
600 (Na2Oeq. = 0.49%) 2.94 0.027
700 (Na2Oeq. = 0.49%) 3.43 0.031
800 (Na2Oeq. = 0.49%) 3.92 0.039
600 (Na2Oeq. = 1.25%) 7.5 0.098
700 (Na2Oeq. = 1.25%) 8.75 0.123
800 (Na2Oeq. = 1.25%) 10 0.132
Clemson University 22/36
Effect of Alkali Loading in Concrete on
Expansion in MCPT
R² = 0.9937
0.000
0.020
0.040
0.060
0.080
0.100
0.120
0.140
0.160
0 5 10 15
% E
xp
an
sio
n a
t 56
Da
ys
Alkali loading Na2Oe%, lb/yd3
HA Cement
LA Cement
Clemson University 23/36
Effect of Vol.Fraction of CA on Expansion in
MCPT
Clemson University 24/36
Effect of Fly Ash Dosage on Expansion in MCPT
0.000
0.020
0.040
0.060
0.080
0.100
0.120
0% 10% 20% 30% 40%
Exp
an
sion
, %
Dosage %
Low Lime
High Lime
Clemson University 25/36
Evaluating Job Mixture ASR Potential
o (a) Standard MCPT tests
o Control Test - 100% Cement (Std. Test Proportions)
o Mitigation Test – SCM Dosage (Std. Test Proportions)
o (b) Job MCPT test
o Control Test – 100 % Cement (per job mix proportions)
o Mitigation Test – SCM Dosage (per job mix proportions)
Clemson University 26/36
ASR Performance Index of Concrete (PI)
o ASR Performance Index (PI) can be defined as follows:
PI = [(Ec- Ej) x100%] / Ec
o Ec = 56-day MCPT expansion of control MCPT mixture
o Ej = 56-day MCPT expansion of mitigated MCPT mixture
Clemson University 27/36
Job mix and Job control mix expansion curves
0.0070
0.0550
0.00
0.04
0.08
0.12
0.16
0.20
0 7 14 21 28 35 42 49 56 63 70 77 84
Exp
an
sion
, %
Age, Days
Victor Job Mix (40% slag) Soak Sln =
0.55N NaOH
Victor Control Mix (100% cement) Soak
Sln = 0.55N NaOH
0.0515
0.00
0.04
0.08
0.12
0.16
0.20
0 7 14 21 28 35 42 49 56 63 70 77 84
Exp
an
sion
, %
Age, Days
Tango Control (100% cement) Soak Soln.
0.55N
Tango Job-mix (15% fly ash) Soak soln.
0.55N
Pijob = 87% Pijob = 1%
Clemson University 28/36
ASR Performance Index of Concrete (PI)
o PIstandard = [(Esc- Esm) x100%] / Esc
o PIJob = [(Ejc- Ejm) x100%] / Ejc
o Example Specification Could be:
PIJob > 0.90 x PIstandard
Clemson University 29/36
Conclusionso The proposed MCPT method overcomes many of the
deficiencies of existing standard ASR test methods
o MCPT Method shows potential to be a reliable and a rapid test
method to evaluate wide range of aggregates and ASR
mitigation measures and provides a result comparable to ASTM C 1293 test in a much shorter duration of only 8 to 12
weeks.
o Among the mixture proportion variables considered, the alkali
loading in concrete and SCM dosage level appear to be the
dominant factors affecting the ASR expansion.
o Preliminary testing to evaluate job mixtures using MCPT
appears to be promising, and the performance index (PI) may
provide a quantifiable way to assess ASR potential of job mix.
Clemson University 31/36
Key Questions for MCPT
o Why 56 days?
o Why 60ºC storage temperature?
o Why 1N NaOH Soak Solution?
o Why a dry-rodded aggregate volume
fraction of 0.65 in the concrete?
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