Controlling Technology for
Concrete Cracking
Changwen Miao
Southeast university
Jiangsu Research Institute of Building Science
State Key Laboratory of High Performance Civil Engineering Materials
July, 2012
Outlines
 Harmfulness of concrete cracking
 Main reasons for concrete cracking
 New technologies for concrete cracking
controlling
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Harmfulness of concrete cracking
Cracking is still a common problem of concrete
Concrete is the cornerstone for civil engineering, hydraulic and
construction projects
Concrete cracking is a common problem in civil construction
projects
Affect the use of safety !
Shorten the service life !
Huge economic loss !
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Concrete cracking declines structural capacity
 Changing the force condition of the
concrete structure, leading to local and
even the overall failure of buildings
 Weakening the stiffness of the concrete
buildings with the dynamic changes of
environment and loads
 Reducing the structural seismic capacity,
threatening the overall stability and
safety of concrete structures
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Concrete cracking deteriorates structural durability
 Stage Ⅰ—Reducing the effective thickness of protective layer
 Stage Ⅱ—Accelerating the transmission of environmental
aggressive media, air and moisture within the concrete structure
 Stage Ⅲ —Shortening activation and corrosion time of
reinforcement, reducing the service life of concrete structures
Stage Ⅰ
Concrete
cracking
Stage Ⅱ
Aggressive media, air,
moisture intrusion
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Stage Ⅲ
Reinforced steel bar
initial corroding
Reinforced steel bar
volume expansion
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Main reasons for concrete cracking
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The causes of cracks
 Load-induced cracks ( structural cracks, about 5%-10%)
Cracks induced by direct stress of external loads (static , dynamic load) , and
Structural secondary stress
 Deformation-induced cracks ( non-structural cracks, 80% or
more)
Plastic shrinkage
Self-desiccation shrinkage
Drying shrinkage
Temperature shrinkage
Humidity changes
Temperature changes
Carbonation shrinkage
 Coupling ( deformation and load ) effect-induced cracks (5 % to
10% )
 Cracks induced by alkali-aggregate reaction, freezing and
thawing, uneven expansion, bad soundness and so on
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Categories of concrete cracking
Settlement cracks
Shrinkage (drying shrinkage,
autogenous shrinkage) cracks
plastic cracks
Shear cracks
Temperature
cracks
Corrosion cracks
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Shrinkage and cracking of concrete in plastic stage
Capillary negative pressure
 The plastic phase can be divided into two stages
Stage 1
Stage 2
No internal
stress generated
Internal pore negative pressure
rising
Time
No shrinkage stress inside the paste
(saturated), mainly in the forms of
bleeding and plastic settlement
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Shrinkage stress (pore negative
pressure) generated
Mainly in the forms of horizontal
plastic deformation and settlement
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Shrinkage and cracking of concrete in plastic stage
 Settlement and bleeding
crack
bleeding
Aggregate
钢筋
water
Micro-crack formation caused by internal bleeding.
Cracks formation due to constraint of subsidence by reinforcement.
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Shrinkage and cracking of concrete in plastic stage
 Mechanics of plastic shrinkage and cracking
2
P 
cos 
r
The shrinkage driving force
is greater than the tensile
strength between particles
Bleeding rate≧Evaporation rate Bleeding rate < Evaporation rate
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Shrinkage and cracking of concrete in plastic stage
 Drying shrinkage cracking—Evaluation methods
60
deformation /10-6
Ring method—double ring
40
outer ring
20
time/d
0
0
-20
2
4
6
8
10
inner ring
-40
Can test out the expansion and shrinkage
stresses
Suitable for evaluation of expansive concrete
(Patent Application No. : 201010100449.7 )
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Autogenous shrinkage of concrete
 Autogenous shrinkage-mechanics
Root reason: the total volume decreases during cement hydration process
(chemical shrinkage) .
Autogenous shrinkage
(Apparent volume decreases)
Volume
Cement
Chemical
shrinkage
Pore
+
Water
Hydration
products
Before hydration
After hydration
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 Chemical shrinkage is about:
6.4×10-2 mL/g；
 Autogenous shrinkage is one of
the manifestations of chemical
shrinkage, chemical shrinkage
equals to the sum of autogenous
shrinkage and pore volume
formed
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Autogenous shrinkage of concrete
 Autogenous shrinkage-mechanics
2
RT
P 
cos   
ln( RH )
r
M
Direct reason:
Initial state
Before structure
formation
After structure
formation
After structure formation, further hydration cause to the meniscus
generation inside the paste and the shrinkage stress
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Autogenous shrinkage of concrete
 Autogenous shrinkage-testing methods
Autogenous shrinkage
(apparent volume decreases）
Concrete
Cement
paste
Corrugate pipe testing method
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 Solving the defect that test ends of pipe
debond with internal concrete in the
vertical length measurement;
 Solving the interference of the probe to
the early test results by using noncontact sensor technology;
 Realizing the staged and whole process
testing since casting and molding,
improving data reliability and continuity.
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Autogenous shrinkage of concrete
 Autogenous shrinkage-testing methods
Physical and mechanical
characteristic parameters
Early shrinkage driving force test since
self-drying zero
Pore negative pressure
testing method
time
 Application of semi permeable membrane characteristics of
the water-saturated porous ceramic probe
self-drying “time-zero”
 Realizing the characterization of initial structure formation
and self- drying 0:00
Corresponding to the initial
 Solving the leak problem of traditional testing method, with
structure formation;
test range upgrading 1 times
Corresponding to the starting  Overcoming the international problem that traditional
point of autogenous shrinkage
method is difficult to test the shrinkage driving force in the
humidity
stage
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Jiangsu Research
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17
Temperature deformation and cracking of concrete
 Temperature deformation—mechanics
1.Material inherent properties
Temperature
rising
Causing expansion
2.Capillary pore stress relaxation
Additional expansion
3.Liquid phase migration
Delayed shrinkage
（ignored usually）
Thermal expansion deformation properties
is significantly affected by humidity
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Temperature deformation and cracking of concrete
 Temperature deformation and cracking
Cracking reason-Thermal stress caused by temperature
difference between inside and outside
90
thickness
center temperature of the thickness
/ oC
85
Temperature
distribution
Adiabatic temperature rise
80
75
70
5m
65
4m
60
3m
55
50
2m
45
40
1m
35
30
25
0
5
10
15
20
25
30
Stress
distribution
Compression zone
time/d
Center temperature rise increases with the
cross-sectional dimensions of the structure
Tension zone
Surface tension, internal compression
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Temperature deformation and cracking of concrete
 Tempreature deformation cracking
Crack criterion
℃
temperature
T1
T2
Tl
e%
strain
s
stress
Ta
elel
e3
e1pl
e2pl
t1
t2
t3
Cracking when tensile stress
t
caused by temperature
deformation and creep is
creep
greater than the tensile
strength of concrete
e4
t
time
t
Temperature Temperature
rises stage
decreases stage
compression
tension
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t
Strength
curve
destroy
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Temperature deformation and cracking of concrete
 Temperature deformation cracking-Evaluation method
Temperature-stress testing machine
Crack resistance parameters
T
Maximum temperature Tmax
Temperature rising time,
Stress occurring time,
The first zero
stress
temperature TZ,1
The first zero stress temperature TZ,1 ,
Temperature peak occurring time,
Maximum temperature Tmax ,
The second zero stress temperatureTZ,2 ,
s
t
Temperature Constant
Rapidcracking temperature T
c
rises stage
temperature cooling stage
stage
Cracking temperature Tc ,
Maximum compressive stress σc,max
σc,max
t
Cracking stress sc
Specimen stress (or center temperature) changes with age
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Temperature deformation and cracking of concrete
 Temperature deformation cracking-Evaluation method
Temperature-stress testing machine
Elastic stress（Hooker Theorem）
12
Relaxation stress
8
4
0
strain（me）
stress（MPa）
Free-form deformation
creep
Constraint + creep (cumulative effect)
Threshold
Deformation
strength
Measured stress(after relaxation)
0
7
14
21
age (d)
28
recovery
0
0
age (d)
Through controlling the total strain of the constrained specimen at 0, and
combining with the reference specimen, functions describing parameters such
as restraint stress, elastic modulus, creep coefficient and so on changing with
time could be obtained.
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Modern concrete cracking reasons are more complex
Conventional concrete
cement
water
fine aggregate coarse aggregate
Optimizing
ratio
and
processes
Mineral admixture
Chemical admixtures
Modern concrete
Composition characteristics
Performance characteristics
complex component
large flowability
low w/c ratio
excellent mechanical properties
more concent of cementitious materials
good durability
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Modern concrete cracking reasons are more complex
 Impact of cement composition and admixture on the
cracking resistance
cement composition and admixture
Cracking temperature
Fineness degree decreasing from 380m2/kg to
Decreasing 9.5℃
280m2/kg
Alkali content decreasing from 0.95% to 0.55%
Decreasing 7℃
C3A content reduced by 4%
Decreasing 6℃
Mixed with 17% fly ash
Decreasing 2℃
Mixed with slag or silica fume
Increasing the cracking
temperature
The greater the reduction value of cracking temperature, the better the
cracking resistance
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Modern concrete cracking reasons are more complex
 Impact of superplasticizer
Traditional naphthalene
calcium lignosulfonate
blank
shrinking percentage (10-6)
shrinking percentage (10-6)
( condensation polymer )
blank
Time / d
Time / d
• Lower w/c and cement consumption, improving mobility ;
• Increasing concrete shrinkage in the same w/c, dry shrinkage at 60d increased by
20%-40%
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Modern concrete cracking reasons are more complex
Autogenous shrinkage (10-6)
 Impact of W/C
Time / d
Compared to specimen with w/c 0.6:
The autogenous shrinkage of specimens with w/c 0.5,0.45,0.4,0.35,0.3 and 0.25 at
1year increased by 175%, 250%, 275%, 335%,495% and 505%, respectively
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Modern concrete cracking reasons are more complex
 The concrete strength grade is gradually increasing, while
tension and compression ratio is gradually decreasing
 C30 concrete: Tension/compression, about 1/10-1/12
 C50 concrete: Tension/compression, about 1/16
Brittleness increases, lead to a higher
cracking risk
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New technologies for
concrete cracking controlling
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General train of thought
Inhibit water
evaporation
Cementitious
materials hydration
Hydration
heat
Autogenous
shrinkage
Plastic
shrinkage
Drying
shrinkage
Capillary negative
pressure growth
Environmental
temperature
Temperature
changes
water
evaporation
Shrinkage compensation by
expansion
Structure regulation
and control
Hydration heat
regulation
Temperature
shrinkage
crack resistance
by fiber
In-situ toughening
Strength, toughness, creep
Evaluation
methodology
Chemical
shrinkage
Force resistance
Driving force
Cracking
resistance
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Curing technologies in early age
Initial setting,
wiping the surface
Plastic stage
Hardening stage
Hydration
degree
Monolayers with high
evaporation resistance ability
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High performance curing
materials with hydrophobic structure
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Curing technologies in early age—water
evaporation inhibition
 Mechanism
air
controllable structure with hydrophilic
main chain and hydrophobic side chains
Monolayers
bleeding
Inhibition
evaporation by 75%
water evaporation
Water evaporation / g
water
Concrete
Time / min
Inhibition evaporation by 75%
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Curing technologies in early age—New
conservation materials
 Mechanism
Water evaporation
concrete
Particle
aggregation
concrete
Dense membrane with high
evaporation resistance ability
Membrane formation
concrete
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concrete
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Curing technologies in early age—water
evaporation inhibition
Mortar mix proportion
1
2
3
4
Reference
Monolayers
Monolayers can effectively suppress the plastic cracking risk
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Curing technologies in early age—water
evaporation inhibition
Impact of monolayers on pore negative pressure
Monolayers can effectively delay the appearing time of pore negative
pressure inflection point of the surface mortar
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Curing technologies in early age—water
evaporation inhibition
Impact of monolayers on plastic shrinkage
The monolayers can reduce about half of the plastic
shrinkage in the horizontal direction
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Curing technologies in early age—water
evaporation inhibition
 Engineering applications
Dingxin Airport in Gansu Province
( the largest in Asia)
Xigaze Airport in Thibet
Suitable for terrible drying area, it could dissolve the problem of crack and
crust on plastic concrete.
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Curing technologies in early age—New
conservation materials
 Effect
crack
Curing materials
80
(kPa)
pressure
Pore negative
孔隙负压
(kPa)
No curing
Curing materials
Non-curing
60
40
20
0
0
1
2
3
4
时间
Time (h)
/h
Delaying the time when capillary negative
pressure begin to increase and reduce crack
risk.
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Curing technologies in early age—New
conservation materials
The second double of the
Lanxin Railway
Taizhou bridge across yangzi river
Suitable for drying and high temperature condition, it could dissolve the problem of
drying crack of hardening concrete at early stage.
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Chemical techniques for shrinkage-reducing
 General ideas
Water
P 
Effect of the reduction of surface tension
on additional pressure on the curved surface
Water
Schematic diagram of
evaporation of capillary moisture
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2s
r
The surface area of the surface tension
in the pore solution was significantly
reduced, which can effectively reduce
autogenous shrinkage and drying
shrinkage of concrete.
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Chemical techniques for shrinkage-reducing
 Traditional low molecular shrinkage reducing agent
The effect of SRA on Mechanical
Properties of Concrete
(same amout of water)
Shrinkage reduction rate(%)
60
50
0.5%
1.0%
1.5%
2.0%
40
gas content
slump
/%
/cm
30
content
/%
20
0
12.0
10
0.5
0
0
20
40
60
80
100
Age(d)
The effect of SRA with different dosages
compressive
strength/MPa
3d
28d
2.7
28.5
45.1
13.0
1.8
26.3
44.5
1.0
15.0
2.0
24.3
42.3
2.0
18.5
1.9
22.4
39.8
Reduced
shrinkage
contradiction
Reduced
strength
The structure-activity relationship study found that the traditional low molecular
shrinkage reducing agent can not fundamentally solve the problem of declining strength
of concrete.
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Chemical techniques for shrinkage-reducing
 High dispersed comb copolymer shrinkage reducing agent
 The molecular tailoring technology was adopted to make the alkyl polyether with
shrinkage reducing function and steric effect graft to the main chain of copolymer,
then the structure-activity relationship between molecular structure and shrinkage
performance of the grafted copolymer/cement/water composite system was studied,
as a result, a new type amphiphilic and high dispersion comb copolymer class
concrete shrinkage reducing agent has been invented, which realized the unity of
shrinkage reducing and water reducing and dispersion.
Short side chain (shrinkage reducing
group)-shrinkage reducing,
dispersion
Side chain
Long side chain
Long polyether side chain –
steric effect
Adsorption behavior regulation - dispersion
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Chemical techniques for shrinkage-reducing
 High dispersed comb copolymer shrinkage reducing agent
-6
1000
FDN
FDN＋2％SRA
SRPCA
800
600
400
200
0
Self-desiccation shrinkage (×10 )
1200
-6
Settlement shrinkage (×10 )
 Impact on shrinkage at early ages
0
1
2
3
4
5
6
Time, t/h (30min after mixing)
7
8
300
250
FDN
FDN＋SRA
SRPCA
200
150
100
50
0
0
5
10
15
20
25
Time, t/h (from initial setting)
(a) condensed shrinkage
(b) autogenous shrinkage before 1d
43% lower than the naphthalene series
53% lower than the naphthalene series
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Chemical techniques for shrinkage-reducing
 High dispersed comb copolymer shrinkage reducing agent
-6
500
-6
Drying shrinkage/(×10 )
Autogenous shrinkage/(×10 )
 Impact on shrinkage in the mid- or late period
FDN
400
SRPCA
300
200
FDN+SRA
100
0
0
10
20
30
40
50
60
70
80
90 100
Age/d
FDN
160
140
120
100
SRPCA
80
60
FDN+SRA
40
20
0
-20
0
10
20 30 40
50 60 70 80
90 100
Age/d
(a) drying shrinkage
(b) autogenous shrinkage
42% lower than the naphthalene
series at 28d
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180
53% lower than the naphthalene
series at 28d
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Chemical techniques for shrinkage-reducing

High dispersed comb copolymer shrinkage reducing agent
 Impact on plastic cracking
Tablet plastic cracking experimental results
Admixtures
Crack
time/min
Maximum crack width /mm
Crack area/mm2
SRPCA
380
0.27
100.15
FDN
190
1.0
763.32
FDN+2%SRA
280
0.6
293.05
The cracking area is 13% of that of ​naphthalene series, with crack width only 0.27mm.
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Chemical techniques for shrinkage-reducing

High dispersed comb copolymer shrinkage reducing agent
 Impact on shrinkage in the mid- or late period
The ring cracking test results
Admixture
Age of first
racking Tc/d
Crack width Wd
SRPCA
6.5
0d
0.397
1d
0.535
3d
0.744
7d
0.936
14 d
1.093
28 d
1.134
FDN
4.5
0.989
1.261
1.75
1.824
2.022
2.033
FDN+2%SRA
7.0
0.693
0.767
0.846
0.933
1.106
1.155
Crack width reduced more than 45% compared with the naphthalene series
Realizing a unified effect of water reducing and shrinkage reducing at a lower dosage,
effectively reducing the plastic shrinkage, early and late autogenous shrinkage and
drying shrinkage .
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Chemical techniques for shrinkage-reducing
 Shrinkage-reducing type polycarboxylate superplasticizer
Lower content，
_ _ _ _ _
Side chain (SRA)
shrinkage
reducing
dispersion
-6
300
250
FDN
FDN＋SRA
SRPCA
200
150
100
50
53% lower than the naphthalene
0
0
5
10
15
20
25
Time, t/h (from initial setting)
dispersion and
180
FDN
160
140
120
100
SRPCA
80
60
FDN+SRA
40
20
53% lower than
the naphthalene after 28 days
0
-20
0
10 20 30 40 50 60 70 80 90 100
Age/d
(a) Autogenous shrinkage before 1st day
江苏省建筑科学研究院有限公司
between
reduced shrinkage
Autogenous shrinkage/(×10 )
-6
Self-desiccation shrinkage (×10 )
Long side chain
unified function
(b) Autogenous shrinkage
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46
Chemical reduction techniques
 Engineering
Applications of shrinkagereducing type polycarboxylate
superplasticizer
applications
Model road tunnel
Shrinkage deformation and
the maximum temperature rise
are controlled within a
reasonable range
The main structures were
not cracked and leaking
Suzhou Dushu Lake Tunnel
Gongboxia Hydropower
Station
Applications of shrinkage reducing admixtures(SRA)
CFRD concrete , the effects of reduced cracking is
significant
Wuxi Lihu Tunnel
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Shrinkage-compensating technology by expansion
Composition
characteristics:low
W/B，low porosity
Shrinkage cracking
characteristics:
shrinkage caused by
autogenous, dry and
thermal factor
Characteristics of the
environment:
temperature and
humidity history
Mutiple
complex
between Ca
and Mg
CaO by light
burning
MgO with
high activity
MgO with
high activity
江苏省建筑科学研究院有限公司
Stable hydration
products
Small water
requirement
Early expansion
Medium-term
expansion
Improve concrete anti-cracking capacity
Controlled and
regulated
expansive history
Large expansive
performance, low
dehydration
shrinkage
Compensating autogenous and thermal
shrinkage , and reducing dry shrinkage
 Thought
Later expansion
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48
Shrinkage-compensating technology by expansion
 Deformation performance
300
200
100
0
0
10
20
Time/d
Time/d
0
0
30
Deformation/10
-6
-100
-200
-300
-400
-500
C30 Reference
C30 SBTJM-MC
C50 Reference
C50 SBTJM-MC
60
30
40
-6
Water curing
Deformation/10
deformation/10
-6
400
Waterproof curing
200
C30 Reference
C30 SBTJM-MC
C50 Reference
C50 SBTJM-MC
100
Time/d
0
0
30
60
90
120
-100
-200
-300
C30 Reference
C30 SBTJM-MC
C50 Referrence
C50 SBTJM-MC
 Expansion rate can be controlled
 Autogenous shrinkage can be inhibit
90
120
effectively
Dry curing  Dry shrinkage can be significantly
reduced so that stable period can be in
advance. In the standard dry condition
without curing, dry shrinkage rate for C50
with the content of 8% was only 45% of
the reference concrete after 120 days.
江苏省建筑科学研究院有限公司
Jiangsu Research Institute of Building Science
Shrinkage-compensating technology by expansion
 Crack resistance performance---Ring method
Cracking time and initial crack width
Cracking time
Initial crack width/mm
C30 reference
4d 21h
0.1
C30 with expansive agent
11d 3h
0.05
C50 reference
4d 18h
0.03
C50 with expansive agent
7d 16h
0.01
C30 （a）reference （b）with expansive agent
江苏省建筑科学研究院有限公司
C50（a）reference （b）with expansive agent
Jiangsu Research Institute of Building Science
Shrinkage-compensating technology by expansion
 Crack resistance performance ---Improved ring method
16
10
Reference
0
0
2
4
6
8
10
12
14
16
-5
-10
inner ring
-15
deformation/10
deformation/10-6
-6
outer ring
time/d
5
Expansive agent
12
outer ring
8
4
time/d
0
0
4
8
12
16
-4
inner ring
-8
-20
1.2
reference
0.8
stress/MPa
Crack resistance performance of
concrete(drying shrinkage of double ring)
development rate of the average
0.4
0.0
0
-0.4
-0.8
Cracking time
time/d
4
8
12
Cracking risk
(MPa/d)
16
reference
14<T C
mixed with expansive agent
Expansive
14<T C
agent
江苏省建筑科学研究院有限公司
stress
0.2>q>0.1
low
0.1>q
Very low
Jiangsu Research Institute of Building Science
Shrinkage-compensating technology by expansion
 Crack resistance performance—TSTM（C30）
Key testing parameters comparison
Unit
Expansive agent
Non expansive
agent
MPa
0.78
0.29
h
49.3
37.9
Maximum expansion values( constraint)
×10-6
37.6
36.3
Maximum expansion values(free)
×10-6
220
148
h
57.2
46.2
Maximum temperature
℃
38.2
35.5
Maximum temperature rise
℃
29.4
27.0
The second zero stress temperature
℃
34.9
35.5
The second zero stress time
h
109.0
70.9
Stress at room temperature(20℃）
MPa
0.22
0.15
Cracking stress
MPa
>3.1
2.0
92.9%
92.5%
Parameter
Maximum compressive stress
Time corresponding to maximum
compressive stress
characteristic parameters of
temperature-stress test
Time corresponding
expansion values
to
Maximum
Stress reserves
Comprehensive evaluation index
Cracking time
h
>164.4
148.4
Cracking temperature
℃
<-18.2
-7.9
江苏省建筑科学研究院有限公司
Jiangsu Research Institute of Building Science
Shrinkage-compensating technology by expansion
 Engineering applications
180
500
Autogenous volume-6
自生体积变形(×-610
deformation(10
) )
160
settlement shrinkage/10
plastic shrinkage/10
-6
-6
140
400
120
100
300
200
100
60
40
20
0
0
0
-100
80
5
10
15
20
25
Age/h
Deformation in early age
0
4
8
12
16
龄期(d)
Age/d
20
24
28
Deformation in later age
Compensating concrete autogenous shrinkage on
phased as well as whole process
Falls Hydropower Station in Sichuan
Typical engineering
North Square of Nanjing South Station of Beijing-Shanghai high-speed railway
Olympic Sports Center in Xuzhou
Samsung sewage treatment plant in Suzhou Industrial Park
Phase II project of Nanjing Lukou International Airport
Zhenjiang Exit Underground Engineering
Media Center Building in Changzhou
江苏省建筑科学研究院有限公司
Jiangsu Research Institute of Building Science
53
Controlling technology of heat hydration
hydrated heat release rate
 Thinking
Rapid reaction period
Acceleration and
Induction period deceleration period Stabilized reaction period
hydrate
Time/h
Concrete temperature rising mainly due to:
Rapid hydration and concentrated exothermic of C3A and C3S phases
江苏省建筑科学研究院有限公司
Jiangsu Research Institute of Building Science
54
Controlling technology of heat hydration
 Thinking
Water structure
Multi-hydroxy or polyhydroxycontaining structure
+
CaCl2
PAA-g-MPEGNa
[a]
[b]
Adsorption and calcium chelation of hydroxyl in additive agent molecules
Inhibition of Ca(OH)2
crystallization
Regulation of condensation process and
hydrated heat release rate
4
放热速率（mw/g）
release rate(mw/g)
hydrated heat
Reduce the hydration rate of
C3A and C3S phase
3
Reference
2
1
0
0
2
4
6
8
Time/d
时间（d）
10
江苏省建筑科学研究院有限公司
12
Jiangsu Research Institute of Building Science
55
Controlling technology of heat hydration
Water structure
Admixtures with special
molecular structure
15
CaCl2
100%Cement
12
-1
Hydration heat rate/(J(g.s) )
Peak value was
reduced by 60%
+
PAA-g-MPEGNa
[a]
Controlling the process
of cement hydration
9
100%Cement+FDN
6
100%Cement+PCA
70%Cement+30%Fly ash+PCA
3
0
0
24
48
72
江苏省建筑科学研究院有限公司
120
144
168
/ (J/g)
250
heat of hytration
Improve capabilities of
temperature control of Mass
concrete
96
Time/h
300
Controlling heat release
of cement hydration
[b]
200
150
100%Cement
100
100%Cement+FDN
100%Cement+PCA
50
70%Cement+
30%Fly ash+PCA
0
0
24
48
72
96
120
144
168
168
Time(h)
Jiangsu Research Institute of Building Science
56
Controlling technology of Heat hydration
No cracks in about 600m3
mass concrete in the thirdphase project of Three
Gorges.
Three Gorges Project
Prather onzalez dam in
Sudan
High friction Zam
Hydroelectric in Pakistan
Jinping Hydropower Station
江苏省建筑科学研究院有限公司
Jiangsu Research Institute of Building Science
57
In-situ toughening technology
 Mechanism--chemical bonding
]
]
[
[
Cement-based materials
Silylated cement particles
m
m
Covalent
bond
Cement-based materials
Chemical bond
formation
江苏省建筑科学研究院有限公司
Structure of organicinorganic hybrid
Jiangsu Research Institute of Building Science
58
In-situ toughening technology
 Concrete performance —Fracture energy
2.5
7d fracture energy
2.0
PH max
KIC
W1
W2
GF
（7d）
(KN)
(MPa· 𝐦)
(N·m)
(N·m)
(N·m-1)
blank
3.26
0.81
0.578
0.242
96
1
3.96
0.98
1.137
0.398
179
2
3.82
0.94
1.212
0.615
213
7d
Reference
Content 1%
Content 0.5%
1.5
P/kN
编号
No.
1.0
0.5
0.0
0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5
CMOD/mm
3.0
28d fracture energy
2.5
编号
No.
PH max
KIC
W1
W2
GF
（28d）
(KN)
(MPa· 𝐦)
(N·m)
(N·m)
(N·m-1)
blank
4.04
1.00
0.709
0.27
115
1.0
1
4.70
1.16
1.49
0.48
231
0.5
2
5.22
1.29
1.13
0.69
213
0.0
28d
Reference
Content 1%
Content 0.5%
P/kN
2.0
1.5
-0.1 0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
1.1
1.2
CMOD/mm
江苏省建筑科学研究院有限公司
Jiangsu Research Institute of Building Science
59
In-situ toughening technology
 Project—Taizhou brigde（Box girder—small thickness,
Low volume-surface area ratio）
 Good dispersion，w/b up to 0.33，Good fluidity retention
capacity
 No cracks occurred
reference
toughening material
江苏省建筑科学研究院有限公司
Jiangsu Research Institute of Building Science
60
Conclusions
 To control the concrete cracking is entirely possible as long as
appropriate measures are used.
 Evaporation reducing and water-retention materials can reduce
water evaporation by up to 75%, which can improve the concrete
crack resistance significantly in early age.
 Unlike traditional polycondensation type superplasticizer, the
new generation graft copolymer can realize molecular design and
graft appropriate functional groups to achieve the unity of water
reduction and shrinkage reduction.
 Admixtures can control hydration exothermic process,
improving temperature control capabilities of mass concrete.
江苏省建筑科学研究院有限公司
Jiangsu Research Institute of Building Science
61
Conclusions
 Multiple compound expanding agents of calcium oxide
and magnesium oxide, can play the expansion roles of active
calcium oxide and light burned magnesia in different periods,
to compensate for concrete shrinkage in the whole process, and
to enhance the crack resistance.
 As the compressive strength is increased and tensile and
compressive strength ratio is decreased, in-situ toughening
technology can be used to enhance the fracture energy and
reduce the cracking risk of concrete.
江苏省建筑科学研究院有限公司
Jiangsu Research Institute of Building Science
62
Thank you!