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Faculty of EngineeringDivision of Built Environment
Laboratory of Engineering for Maintenance System
Hokkaido University
Clarification of Frost Damage Mechanism Based on Meso scale Deformation and Temperature
and Moisture Change
EVDON LUZANO SICAT, M1
Clarification of Frost Damage Mechanism based on Mesoscale Deformation and Temperature and Moisture ChangeLaboratory of Engineering for
Maintenance System
LOGOContents
RESEARCH OUTLINEB
EXPERIMENTAL OUTLINEC
BACKGROUND:FORST DAMAGE MECHANISM
A
Clarification of Frost Damage Mechanism based on Mesoscale Deformation and Temperature and Moisture ChangeLaboratory of Engineering for
Maintenance System
LOGOBackground
Freeze-thaw DeteriorationConcrete, like other highly divided porous media, has the
ability to absorb and retain moisture. This characteristic has an important consequence since unprotected concrete structures in contact with water are usually susceptible to frost damage.
Clarification of Frost Damage Mechanism based on Mesoscale Deformation and Temperature and Moisture ChangeLaboratory of Engineering for
Maintenance System
LOGOBackground
Frost Damage MechanismConcrete Condition: Unsaturated• The pore structure is filled by small amount of water.• Once temperature drops to 0ºC – Thermal contraction
occurs.• From 0ºC to minimum temperature – Water in larger
pores freezes.
• From freezing temperature to thawing – ice melts and
water flows to pore spaces.
ice
water
Clarification of Frost Damage Mechanism based on Mesoscale Deformation and Temperature and Moisture ChangeLaboratory of Engineering for
Maintenance System
LOGOBackground
Frost Damage Mechanism Concrete Condition: Saturation Process- Possible only if water is available outside during thawing at
temperature above 0ºC.- When freezing for temperature below 0ºC – water freezes and
volume expands (can create tension to concrete).- At temperature below -10ºC to minimum temperature – ice
contracts in larger pores.-
- From minimum temperature to -5ºC during thawing – ice expands more than surrounding concrete.
Contracted Ice
water
Increment pore space
Clarification of Frost Damage Mechanism based on Mesoscale Deformation and Temperature and Moisture ChangeLaboratory of Engineering for
Maintenance System
LOGOBackground
Frost Damage MechanismConcrete Condition: Saturated Condition- In this condition, the pore structure is totally filled by water.- As temperature continues to drop, the expansion of water creates
a very high positive hydraulic pressure.- For lowest temperature – water in smaller pores also freezes.
Ice
Larger cracks
Smaller pores begin to freeze
Clarification of Frost Damage Mechanism based on Mesoscale Deformation and Temperature and Moisture ChangeLaboratory of Engineering for
Maintenance System
LOGOResearch Outline
Objective:To clarify the effect of temperature history and moisture conditions on concrete that are under the effect freezing and thawing actions.
Previous Model Consideration (Oiwa-san’s Model):Strains caused by temperature difference and ice formation.
Where: εT is linear expansion strain, α is linear expansion coefficient;10 [/℃], Td is temperature difference, εi is expansion strain caused by ice formation, αi is freezing expansion coefficient; 6250 [μ], Ψi is ice content.
dT Tiii
Clarification of Frost Damage Mechanism based on Mesoscale Deformation and Temperature and Moisture ChangeLaboratory of Engineering for
Maintenance System
LOGOResearch Outline
Some considerations: Residual strain was not taken into account
during freezing and thawing cycles.
Specimens are analytical model, for its viability: results must have a comparison with experimental data.
Super cooling and expansion of water when freezing are not considered.
Clarification of Frost Damage Mechanism based on Mesoscale Deformation and Temperature and Moisture ChangeLaboratory of Engineering for
Maintenance System
LOGOResearch Outline
Model Proposal (Arai-san’s Paper):
The total strain ε for the transformation model of mortar due to frost damage is assumed to be composed of three strains which are presented as follows:
εi: Expansion strain when freezingεs: Shrinkage strain when freezingεt: Temperature strain
tsi
Clarification of Frost Damage Mechanism based on Mesoscale Deformation and Temperature and Moisture ChangeLaboratory of Engineering for
Maintenance System
LOGOResearch Outline
The model of expansion strain when freezing εi is a function of ice content ratio Ψi. When moisture content ratio is small, the expansion is not caused. Then, the following expressions are assumed.
αi: Constant of proportion that changes by rigidity of mortarΨic: Ice content ratio when transformation began to depend on ice content ratio
The shrinkage when freezing is thought to be shrinkage by the movement of the unfrozen water. It is expressed as follows by assumption that the transformation depends on the unfrozen rate.
αs: Constant of proportion that shows unfrozen rate contributes to shrinkage. It changes by the rigidity of mortar.)ψ: moisture content ratio
The temperature strain is expressed as follows by linear coefficient of expansion αt.
ΔT: Temperature difference
iciii -
iss -
Ttt
Clarification of Frost Damage Mechanism based on Mesoscale Deformation and Temperature and Moisture ChangeLaboratory of Engineering for
Maintenance System
LOGOExperimental Plans
Purpose of the Experiment:
To obtain the following coefficients experimentally; thermal expansion , freezing expansion , and shrinkage contraction and then apply them in the proposed frost damage mechanism model.
- Freezing strain
- Shrinkage strain
- Thermal Strain
iciii -
iss -
Ttt
t is
Clarification of Frost Damage Mechanism based on Mesoscale Deformation and Temperature and Moisture ChangeLaboratory of Engineering for
Maintenance System
LOGOExperimental Plans
Specimens to be Used
Mortar will be use as test specimen in this experimental program.
A. Materials Characteristics:Cement – Ordinary Portland cement (Density: 3.14
g/cm3)
Fine Aggregate (from Mukawa) (Size: 1.2mm and Density: 2.67 g/cm3)
Air-Entraining Agent – None (To Promote Frost Damage)
Water cement ratio
（％）
Water（ kg/m3
）
Cement（ kg/m3
）
Fine Aggrega
te（ kg/m3 ）
50 244.6 489.2 1467.6
Table-1 Mix Proportions (Mortar)
Clarification of Frost Damage Mechanism based on Mesoscale Deformation and Temperature and Moisture ChangeLaboratory of Engineering for
Maintenance System
LOGOExperimental Plans
Preparation of Specimens
Casting and mold - 40 x 40 x 160 mm form
Curing Period – 60 days (Moist Condition - 23ºC) Specimen dimension - 40 x 40 x 2 mm
Table -2 (Specimen set and Moisture Conditions)
5 Specimens/Set Moisture Condition Purpose
A Absolutely Dry Thermal Expansion
B (Nearly or Fully) Saturated Freezing Expansion
C 20 - 50% Saturated Shrinkage Contraction
D 80 –90% Saturated Comparison to Model’s Output
Clarification of Frost Damage Mechanism based on Mesoscale Deformation and Temperature and Moisture ChangeLaboratory of Engineering for
Maintenance System
LOGOExperimental Plans
To attain different kind of moisture conditions on specimens, they will be subjected in different desiccators with different kind of salt solution.
Table-3 Salts solutions Desiccators
Salts
(Potassium Nitrate) KNO3
(Potassium Chloride) KCl
Chloride) NaCl
Graph from AGM Container Controls, Inc. (AGM)
Clarification of Frost Damage Mechanism based on Mesoscale Deformation and Temperature and Moisture ChangeLaboratory of Engineering for
Maintenance System
LOGOExperimental Plans
Experimental Set-up
Specimens
Data logger
PC
Environmental Chamber
Temperature sensorSpecimen support
Temperature History Cycle for Set A, B, and C Specimens
Temperature History Cycle for Set D Specimens
Temperature increment:
0.5ºC/minute
OL
L )( 0TT
L
L
O
Coefficients , , and can be approximated by formula of coefficient of linear expansion.
t is
Faculty of EngineeringDivision of Built Environment
Laboratory of Engineering for Maintenance System
Hokkaido University
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