1. Internal Curing of Concrete
with
Fine Lightweight Aggregates
Donald M. Smith, PhD,Donald M. Smith, PhD,
Adam Browne, PE, MDOT
Internal Curing of Concrete
with
Fine Lightweight Aggregates
Donald M. Smith, PhD, PE, ConsultantDonald M. Smith, PhD, PE, Consultant
Adam Browne, PE, MDOT
2. Senior Engineer
• 36 years experience in transportation facilities, engineering
materials, geotechnical engineering, pavements
engineering, construction and laboratory testing.
• Expertise in the design, analysis, maintenance,
management, and rehabilitation of rigid, flexible, low
volume and unsurfaced pavements and materials
Donald Mark Smith, Ph.D., P.E.Education
Bachelor of Science,
1983, Civil
Engineering
Mississippi State
University
Master of Science,
1990, Civil
Engineering,
Mississippi State
• Registered Professional Engineer, Mississippi
Mississippi State
University
Doctor of Philosophy
2000, Civil
Engineering,
Louisiana State
University
experience in transportation facilities, engineering
materials, geotechnical engineering, pavements
engineering, construction and laboratory testing.
Expertise in the design, analysis, maintenance,
management, and rehabilitation of rigid, flexible, low
volume and unsurfaced pavements and materials
Donald Mark Smith, Ph.D., P.E.
Registered Professional Engineer, Mississippi
3. Engineer
• 15 years experience in transportation facilities, engineering
materials, construction,
• Expertise in concrete mixtures, concrete durability,
Adam Browne,
Education
Bachelor of Science,
1996, Mechanical
Engineering
Mississippi State
University • Expertise in concrete mixtures, concrete durability,
cementitious materials
• Registered Professional Engineer,
University
15 years experience in transportation facilities, engineering
construction, and laboratory testing.
concrete mixtures, concrete durability,
Adam Browne, P.E.
concrete mixtures, concrete durability,
cementitious materials
Registered Professional Engineer, Mississippi
4. Let’s Start from the Beginning:
1. Portland Cement Concrete
2. Fine Lightweight Aggregates2. Fine Lightweight Aggregates
3. Internal Curing
Let’s Start from the Beginning:
1. Portland Cement Concrete
2. Fine Lightweight Aggregates2. Fine Lightweight Aggregates
6. One Definition of Portland Cement Concrete…
• Portland cement concrete (PCC) is a heterogeneous system of solid,
discrete, gradiently sized, inorganic mineral aggregates, usually plutonic
or sedimentary-calcareous in origin, embedded in a matrix compounded
of synthesized polybasic alkaline and alkaloidal silicates held in aqueous
solution and co-precipitate dispersion with other amphoteric oxides,
this matrix being originally capable of progressive dissolution, hydration,
re-precipitation, gelation and solidification through a continuous andre-precipitation, gelation and solidification through a continuous and
co-existent series of crystalline, amorphous, colloidal and
cryptocrystalline states and ultimately subject to thermo
allotriomorphic alteration, the system when first conjoined being plastic
during which stage it is impressed to a predetermined form into which it
finally consolidates, thus providing a structure relatively impermeable
and with useful capacity to transmit tensile, compressive, and shear
stresses.
•(source unknown)
One Definition of Portland Cement Concrete…
Portland cement concrete (PCC) is a heterogeneous system of solid,
sized, inorganic mineral aggregates, usually plutonic
calcareous in origin, embedded in a matrix compounded
of synthesized polybasic alkaline and alkaloidal silicates held in aqueous
precipitate dispersion with other amphoteric oxides,
this matrix being originally capable of progressive dissolution, hydration,
precipitation, gelation and solidification through a continuous andprecipitation, gelation and solidification through a continuous and
existent series of crystalline, amorphous, colloidal and
cryptocrystalline states and ultimately subject to thermo-
alteration, the system when first conjoined being plastic
during which stage it is impressed to a predetermined form into which it
finally consolidates, thus providing a structure relatively impermeable
and with useful capacity to transmit tensile, compressive, and shear
7. One Definition of Portland Cement Concrete…
• Portland cement concrete (PCC) is a heterogeneous system of solid,
discrete, gradiently sized, inorganic mineral aggregates, usually plutonic
or sedimentary-calcareous in origin, embedded in a matrix compounded
of synthesized polybasic alkaline and alkaloidal silicates held in aqueous
solution and co-precipitate dispersion with other amphoteric oxides,
this matrix being originally capable of progressive dissolution, hydration,
re-precipitation, gelation and solidification through a continuous and
?...........re-precipitation, gelation and solidification through a continuous and
co-existent series of crystalline, amorphous, colloidal and
cryptocrystalline states and ultimately subject to thermo
allotriomorphic alteration, the system when first conjoined being plastic
during which stage it is impressed to a predetermined form into which it
finally consolidates, thus providing a structure relatively impermeable
and with useful capacity to transmit tensile, compressive, and shear
stresses.
•(source unknown)
?...........
One Definition of Portland Cement Concrete…
Portland cement concrete (PCC) is a heterogeneous system of solid,
sized, inorganic mineral aggregates, usually plutonic
calcareous in origin, embedded in a matrix compounded
of synthesized polybasic alkaline and alkaloidal silicates held in aqueous
precipitate dispersion with other amphoteric oxides,
this matrix being originally capable of progressive dissolution, hydration,
precipitation, gelation and solidification through a continuous and
?...........precipitation, gelation and solidification through a continuous and
existent series of crystalline, amorphous, colloidal and
cryptocrystalline states and ultimately subject to thermo-
alteration, the system when first conjoined being plastic
during which stage it is impressed to a predetermined form into which it
finally consolidates, thus providing a structure relatively impermeable
and with useful capacity to transmit tensile, compressive, and shear
?...........
8. Real Definition of PCC…
• A mixture of:
• Portland Cement
• Fine Aggregate
• Coarse Aggregate
• Water• Water
• Air
• Cement and water combine,
changing from a moist,
plastic consistency to a
strong, durable rock-like
construction material by
means of a chemical reaction
called “hydration”
Real Definition of PCC…
Cement and water combine,
means of a chemical reaction
10. ven deeper down the rabbit hole…
Curing is both a state and an
1. Concrete’s state during the transformation from a plasti
heterogeneous mixture to a hardened heterogeneous
mixture.
2. The actions taken to ensure the moisture and temperatu
conditions exist during the transformation from a plastic
state to a hardened state so that the concrete may fullystate to a hardened state so that the concrete may fully
develop its potential properties.
ven deeper down the rabbit hole…
Curing is both a state and an action:
Concrete’s state during the transformation from a plasti
heterogeneous mixture to a hardened heterogeneous
The actions taken to ensure the moisture and temperatu
conditions exist during the transformation from a plastic
state to a hardened state so that the concrete may fullystate to a hardened state so that the concrete may fully
develop its potential properties.
13. A definition of Internal Curing
e process by which the hydration of cement continues because of the availability
nternal water that is not part of the mixing water
ConventionalConcrete
Internalwaterreservoir
Radlinska et al.
Transportation Research Record: Journal of the Transportation Research Board,
No. 2070, Transportation Research Board of the National Academies, Washington,
D.C., 2008, pp. 59–67.
ConventionalConcrete
Internalwaterreservoir
A definition of Internal Curing
process by which the hydration of cement continues because of the availability
nternal water that is not part of the mixing water.“
- ACI Committee 308, Curing Concrete
ConventionalConcreteConventionalConcrete
17. What do we mean by “lightweight”?
mma/pacquiao-honoured-as-best-of-http://www.dailytelegraph.com.au/sport/boxing-mma/pacquiao
decade/story-e6freygr-1225825737810
Manny Pacquiao
What do we mean by “lightweight”?
http://www.cleveland.com/sports/index.ssf/2011/01/evander_holyfield_still_looks.html
Evander Holyfield
http://www.cleveland.com/sports/index.ssf/2011/01/evander_holyfield_still_looks.html
18. A definition of “lightweight aggregate”
ightweight aggregate is an “aggregate made by heating clay [shale or slate] to around 1,200
2,190 °F) in a rotary kiln. The yielding gases expand
ubbles forming during heating producing a honeycomb structure.”
hey “contain a uniformly distributed system of pores that have a size range of approximately 5 to
00μm.”
olclassic.com/?w=TD90WfoPvh8&title=jim-braddock-vs-joe-louis-all-rounds-part-22
00μm.”
A definition of “lightweight aggregate”
is an “aggregate made by heating clay [shale or slate] to around 1,200 °C
F) in a rotary kiln. The yielding gases expand the clay [shale or slate] by thousands of small
ubbles forming during heating producing a honeycomb structure.”
https://en.wikipedia.org/wiki/Expanded_clay_aggre
a uniformly distributed system of pores that have a size range of approximately 5 to
http://www.cptechcenter.org/ncc/TTCC-NCC-documents/Sp2014/SP14-22-Weiss-Internal%
http://www.escsi.org/ContentPage.aspx?i
19. How Internal Curing is accomplished by LWA
Water is released from water-filled
aggregate (LWA) when it is used for I
the IC water needs to be described in
1. the ability of the water to leave the LWA when needed for1. the ability of the water to leave the LWA when needed for
2. the volume of water available for IC,
3. the distribution of the LWA so that it is well
water can readily travel to all of
is needed.
How Internal Curing is accomplished by LWA
filled pre-wetted lightweight
it is used for Internal Curing (IC). As such,
described in three main ways:
the ability of the water to leave the LWA when needed for IC,the ability of the water to leave the LWA when needed for IC,
volume of water available for IC,
so that it is well-dispersed and its
water can readily travel to all of the sections in the paste where it
20. 1. the ability of the water to leave the LWA
terial properties of the LWA:
Absorption – how much water
an it readily contain
htweight.com/index.php/applications
g
an it readily contain
Desorption – how much water
ill it readily give up
ability of the water to leave the LWA
21. 2. the volume of water available for IC
Mass of Lightweight Aggregate Required (lb/CY)
Cement Factor (lb/CY)
Chemical Shrinkage of cement (lb H2O / 100 lb
Degree of Hydration
Absorption of LWA (%)
Desorption of LWA (%)
volume of water available for IC
Amount of water required to replenish
water absorbed by cement
Factors for compensating for LWA Absorption
and Desorption
http://trinitylightweight.com/index.php/applications
/CY)
lb cm)
22. 3. the distribution of the LWA so that it is
well-dispersed
ulations by NIST IC Modeling SW with identical gradations & weights of
LWA as a coarse aggregate LWA as a fine aggregate
distribution of the LWA so that it is
dispersed
ulations by NIST IC Modeling SW with identical gradations & weights of
LWA as a fine aggregate
24. Methods used to detect Internal Curing
The Maturity Method detects temperature differences associated
with cement hydration
• ASTM C 1074, Standard Practice for Estimating Concrete Strength by the
Maturity Method
Surface resistivity detects changes in pore structure, pore solution
concentration, and pore solution amounts
• AASHTO T358, Standard Method of Test for Surface Resistivity Indication of
Concrete’s Ability to Resist Chloride Ion Penetration
Methods used to detect Internal Curing
The Maturity Method detects temperature differences associated
ASTM C 1074, Standard Practice for Estimating Concrete Strength by the
Surface resistivity detects changes in pore structure, pore solution
concentration, and pore solution amounts
AASHTO T358, Standard Method of Test for Surface Resistivity Indication of
Concrete’s Ability to Resist Chloride Ion Penetration
29. • “overall resistivity is dependent
• the resistivity of the fluid in the pores,
• the degree of saturation of the concrete,
• the volume and connectivity of the pore
Surface Resistivity
• the volume and connectivity of the pore
• resistivity decreases with a higher water content (i.e.,
volume) and a more open pore network (i.e., a
tortuosity coefficient)”
stro, J., Nantung, T., Paredes, M., & Weiss, J. Variability Analysis of the Bulk
ured Using Concrete Cylinders. Publication FHWA/IN/JTRP-2011/xx. Joint
Research Program, Indiana Department of Transportation and Purdue University,
Indiana, 2011, DOI: 10.5703/1288284314646
is dependent on three factors:
pores,
degree of saturation of the concrete, and
volume and connectivity of the pore network…
Surface Resistivity
volume and connectivity of the pore network…
with a higher water content (i.e., pore
) and a more open pore network (i.e., a lower
30. Surface Resistivity and Tortuosity
Schematic representations of electron flow through saturated
concrete mixtures demonstrate why mixtures with higher porosities
tend to have lower electrical resistivities: (a) flow through a
highly porous microstructure; and (b) flow through a dense
microstructure
(a) (b)
Surface Resistivity and Tortuosity
“The tortuosity of the pore network
is determined by the microstructure
of the concrete, which develops and
becomes more refined over time due
to cement hydration and secondary
reactions of supplementaryreactions of supplementary
cementitious materials (SCMs).
Denser microstructures, resulting
from SCM additions or higher degrees
of hydration, tend to have
more complex and refined pore
networks, giving the concrete a
higher tortuosity and a lower
permeability.”
37. Experimental
Two mixtures, Control & Lightweight
Conventional mixing techniques
Modified curing protocol:
• Initial curing at 90°F for 3 days• Initial curing at 90°F for 3 days
• Standard moist curing conditions up to 56 days
Standard fresh concrete tests
Hardened concrete tests:
• Compressive strength, surface resistivity, and maturity
Experimental Method
Two mixtures, Control & Lightweight
Standard moist curing conditions up to 56 days
Compressive strength, surface resistivity, and maturity
38. Test ASTM Control
Mixture
Value
Slump C143 1.6
Results of Tests on Fresh Concrete
Slump C143 1.6
Air Content C231 2.3
Air Temperature C1064 69
Concrete
Temperature
C1064 72
Date of Placement -- 09/14/2015
Time of Placement -- 09:00 AM
Unit Lightweight
Mixture
Value
Unit
inches 2.2 inches
Results of Tests on Fresh Concrete
inches 2.2 inches
% 1.9 %
F 74 F
F 75 F
-- 09/14/2015 --
10:00 AM
39. Test Name Test Designation
Compressive Strength AASHTO T22
Resistivity AASHTO T358
ardened Concrete Tests and ASTM Designatio
Resistivity AASHTO T358
Maturity ASTM C1074
Temperature
ASTM C1074
of Maturity)
Test Designation Units
22
Pounds per square Inch,
PSI
358 Kilo-Ohms, KΩ
ardened Concrete Tests and ASTM Designatio
358 Kilo-Ohms, KΩ
1074
Degree[C]Days or
Degree[C]-Hours
1074 (Part
Maturity)
Degrees[C]
40. AverageCompressiveStrength,psi
Effects of Light Weight Aggregate
on Internal Curing
6,400
7,200
8,000
8,800
Age in Days
AverageCompressiveStrength,psi
0 10 20
2,400
3,200
4,000
4,800
5,600
Effects of Light Weight Aggregate
on Internal Curing
CM
LWA
Age in Days
30 40 50 60
Compressive Strength
Control Mixture
Light Weight Aggregate
41. AverageCompressiveStrength,psi
Effects of Light Weight Aggregate
on Internal Curing
5,600
6,400
7,200
8,000
8,800
Age in Days
AverageCompressiveStrength,psi
1 5
2,400
3,200
4,000
4,800
5,600
Effects of Light Weight Aggregate
on Internal Curing
CM
LWA
Age in Days
10 50 100
Compressive Strength
Control Mixture
Light Weight Aggregate
45. Equality Plot of Surface Resistivity (SR)
7
14
y = 0.571x + 4.409
12
14
16
18
20
1
3
7
0
2
4
6
8
10
12
0 5 10
Avg LWA SR values
Equality Plot of Surface Resistivity (SR)
28
56
y = 0.571x + 4.409
R² = 0.930
15 20
Avg LWA SR values
46. Conclusions
For mixture design purposes, accurate absorption values for Fine
lightweight aggregates (FLWA) are very important.
FLWA at the quantities required for Internal Curing do not degrade
strength as one would expect, relative to a control mixture.
Hydration continues longer when using FLWA than a control mixture.Hydration continues longer when using FLWA than a control mixture.
Surface resistivity indicates that a mixture with FLWA densifies faster
than a control mixture.
Questions? ..................................
For mixture design purposes, accurate absorption values for Fine
lightweight aggregates (FLWA) are very important.
at the quantities required for Internal Curing do not degrade
strength as one would expect, relative to a control mixture.
ydration continues longer when using FLWA than a control mixture.ydration continues longer when using FLWA than a control mixture.
Surface resistivity indicates that a mixture with FLWA densifies faster
Questions? ..................................
47. Acknowledgements
The support of the Mississippi Department of Transportation is
acknowledged for funding this research project.
All results, data, and conclusions in this presentation are the property
of the Department.of the Department.
The support of the Mississippi Department of Transportation is
acknowledged for funding this research project.
All results, data, and conclusions in this presentation are the property
