Durable Design of Concrete -Combined Deterioration · Durable design method assuming the premeditated maintenance and repair Our research 1．Estimate of humidity distribution in

01/03/2010 HRI

Durable Design of Concrete

- Combined Deterioration -

Osamu KATSURA

Madoka TANIGUCHI

Chiemi IBA

Hokkaido Northern Regional Building Research Institute

01/03/2010 HRI

The aim through the period

Method to predict progress of the combined deterioration

Durable design method

assuming the premeditated maintenance and repair

Our researchOur research

１． Estimate of humidity distribution in concrete from

weather observation data

２． Prediction of Combined deterioration

・ Deteriorations which decrease strength and elasticity

Frost damage, Fatigue makes many micro cracks

・ Deterioration by the material migration

Salt attack, Carbonation is accelerated by micro cracks

01/03/2010 HRI

Our study in first year

１．Estimation of humidity in concrete.

・ Simulation

Heat and moisture transfer, Adsorption isotherm

An environmental condition

・ Experiment (in winter)・ Experiment (in winter)

Temperature and humidity in concrete

Wetting on the surface

Weather observation data

２． Observation and measuring of micro cracks

Frost damage and fatigue

micro crack length as a common index

01/03/2010 HRI

ESTIMATION OF HUMIDITY IN CONCRETE

Numerical Simulation of Heat and Moisture Transport�Simultaneous heat and moisture transport equations considering

freezing – thawing process

�Calculation using meteorological data and material properties

Measurement of

Moisture Condition

�Wall Model

(150mm thick)

�Column Model

(800mm Cube)

�Surface Wetting

Measurement of

Material Properties

�Adsorption Isotherm

�Other properties from

reference book*(*IEA ANNEX24 Task3 report)

Reference of

Meteorological data �Measured data in HRI,

Asahikawa.

�Climate Statistics data

from Meteorological

Agency

�Expanded AMeDAS

Weather data

Input InputVerification

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� The temperature and the relative humidity

distribution inside concrete are measured

and recorded at intervals of 1 hour.

� Measured data are used to verify the

numerical simulation.

MEASUREMENT OF TEMPERATURE & HUMIDITY

INSIDE CONCRETE WALL UNDER CLIMATIC CONDITION

Wall Model (150mm thick)

numerical simulation.

40mm

7mm

Temperature & Humidity Logger

(Button battery type)

Measurement point:

3mm, 5mm, 8mm, 12mm, 25mm, 50mm

from outer surface

Assume

1-dimensional

moisture transfer

150mm thick concrete wall

100φ core

Aluminum

Foil TapeImpermeable to

water and vapor

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� The temperature and humidity sensors were installed before casting

concrete.

� From measured results in this experiment and in the wall model

experiment, the better measuring method is examined.

Column Model (800mm cube)

MEASUREMENT OF TEMPERATURE & HUMIDITY

INSIDE CONCRETE WALL UNDER CLIMATIC CONDITION

� Measured data are also used to verify the numerical simulation.slope

800mm

800mm

800mm

�Measuring points

→ along --- line

Placed under climatic condition

3mm 5mm 8mm 12mm 25mm

50mm

400mm(center)

Rainwater

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� Wetness sensor detects if liquid water exists on the surface or not.

� The surface temperature are measured along with the wetness

measurement, and thus it can be confirmed whether freezing occurs

or not .

MEASUREMENT OF SURFACE WETNESS

UNDER CLIMATIC CONDITION

Electroconductive paint

Wet surface → Electric resistance decrease

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Meteorological data:Outdoor temperature, Humidity, Solar radiation, Precipitation… Water content distribution

inside concrete wall

NUMERICAL SIMULATION OF

HEAT AND MOISTURE TRANSPORT

Input

Output:Time profile and Distribution of

Temperature, Humidity, Water content…

Outline of Calculation

Material properties:Isotherm, Thermal conductivity, Moisture permeability… Frequency of freezing

Input

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Relative

humidity[%]Solution

Dry LiCl Lithium chloride

33% MgCl2･6H2O Magnesium chloride 6-Hydrate

53% Mg(NO3)2･6H2O Magnesium nitrate 6-Hydrate

75% NaCl Sodium chloride

MEASUREMENT OF MATERIAL PROPERTIES

at 20℃Adsorption Isotherm

( )[ ]553752.1 17.0exp1443.0 hhψ −−=

Specimen

3mm-thick concrete

75% NaCl Sodium chloride

85% KCl Potassium chloride

94% KNO3 Potassium nitrate

98% K2SO4 Potassium sulphate

100% water absorption for 48 hours

Equipment

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� The equations for simultaneous heat and moisture transfer considering

freezing and thawing processes are used. (Gao 1992, Matsumoto et al. 1993).

(i,j-1)

X

Y

Q (i,j), J (i,j)

Δx1 Δx2

Control volume

( ) ( ){ }t

Tt

ii

lgTg

ll

∂

∂−∇′+′⋅∇+∇′⋅∇=

∂

∂ ψρµλλλ

ψρµµ

●Moisture balance

Basic equations

(i,j) (i-1,j) (i+1,j)

(i,j+1)

QX(i,j), JX(i,j) QX(i+1,j), JX(i+1,j)

QY(i,j), JY(i,j)

QX(i,j+1), JX(i,j+1)

T(i,j), µ(i,j), ψl(i,j) , ψi(i,j)

Δy1

Δy2

1-dimentional or 2-dimentional

calculation

●Energy balance

( ) ( ) ( ){ }t

HTHTt

Tc ii

ligTggl ∂

∂+∇′⋅∇+∇′⋅∇+∇⋅∇=

∂

∂ ψρµλλλρψ µ

●Freezing condition

=

oeli TTH logµ

T = absolute temperature [K]; T0 = freezing temperature of free water (=273.16) [K]; c = specific heat [J/kgK]; t = time [s];

λ = thermal conductivity [W/mK]; ρ = density [kg/m3]; Ψ = moisture content [m3/m3];

µ = water chemical potential (free water standard) [J/kg]; λ’T = moisture conductivity by temperature difference [kg/msK];

λ’µ = moisture conductivity by water chemical potential difference [kg/ms(J/kg)]

Subscript w = water; s = solid; g = gas; l = liquid; i = ice

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� The calculation is conducted for the column model using the weather data

measured in Asahikawa.

� The calculation period starts on November 24,2009.

� Initial relative humidity is set at 99.9%



Calculation Conditions & Results

Colum Model

Now working on…

Initial relative humidity is set at 99.9%

(nearly saturated).

Colum Model

center

1-Dimentional

heat and moisture

transfer

400mm

400mm

South

In Laboratory

Outside

3mm 25mm 400mm

01/03/2010 HRI



Calculation Results

Temperature

CalculationExperimentTime profile

3mm 25mm 400mm

Relative humidity

3mm 25mm 400mm

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PREDICTION OF COMBINED DETERIORATION

Degradation of

material propertyFor example…

Strength/Stiffness

Factor of Deterioration

Frost Damage

and so on…

Carbonation depth

time

damaged

time

damagedShrinkage

Fatigue Loading

Thermal stress

And so on…

Micro crack

01/03/2010 HRI

OBJECTIVE

Using a common index

1.Evaluate the deterioration level

caused by freezing and thawing or

Micro crack in

concrete

observed with

microscope

caused by freezing and thawing or

fatigue loading

2.Relate deterioration level to the

degradation of permeability

01/03/2010 HRI

EXPERIMENTAL PLAN

Observation and measuring of micro cracks caused by

frost damage and fatigue loadingRelation between energy and crack

Comparison of micro crack with different cause

Phase 1

Phase 2

Degradation of strength and stiffnessStrength: External work, micro crack length and strength and stiffness

Frost damage: micro crack length, damage level and strength and

stiffness

Phase 2

Degradation by combined effect of deterioration factorsFrost damage and carbonation

Fatigue loading and carbonation

Phase 3

We can predict progress of the combined deterioration

01/03/2010 HRIPHASE 1OBSERVATION AND MEASURING OF MICRO CRACKS

CAUSED BY FROST DAMAGE AND FATIGUE LOADING

� Does the crack that we detected become

the index? � Relation between energy and crack

• Micro Cracks caused by Fatigue Loading

• It is examined that relation between external works and the crack

length.

� Comparison of micro crack with different cause

• Micro Cracks caused by Frost Damage or Fatigue loading

• The damage level and the form of the crack are examined.

01/03/2010 HRI

PHASE 1EXPERIMENTAL WORK

� Micro Cracks by Loading� W/C=0.48 Ordinary Portland cement concrete

� Concrete cylinder was loaded in uniaxial compression. It

was single loading. Stress-strain curve was obtained.

� The nominal level of compressive stress on each

cylinder was targeted for 0,40,60,80,100% of the

maximum compressive strength.

� The cylinder was cut at ½ height,

and the micro crack was observed.

01/03/2010 HRI

PHASE 1EXPERIMENTAL WORK

� Micro Cracks by freezing and thawing� W/C=0.48 Ordinary Portland cement concrete

� Freezing and thawing test: ASTMC666A,B

(JISA1148A,B) and CIF test

� Relative dynamic modulus of elasticity 80,70,60%

� The micro crack was observed at each damaged level.

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� Sample preparation� Cut with the diamond saw. Grind and polish the surface. The

fluorescent paint is painted and soaked. Exessive paints are

polished and removed.

� Microscopic Instruments

PHASE 1DETECTION OF MICROCRACKS IN CONCRETE

� Microscopic Instruments� Nikon Stereoscopic Zoom Microscope SMZ1000 and sony digital

camera mounted on the microscope were used. Magnification is

between about x10~x300.Uitraviolet light was used.

01/03/2010 HRI


� Micro crack Quantification� The whole of the sample was

divided into the grid, and it was

taken a picture. This has been

expanded to almost 100 times. The

size in one grid was 7x4mm. The

number of all images is about 300.

� Using the image analysis software

Image-pro PLUSTM ver.4.5.1 by

Media cybernetics.

×100

1mm

7mm

4m

m

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MEASUREMENT OF SURFACE WETNESS

UNDER CLIMATIC CONDITION

01/03/2010 HRIMeasurement of Surface Wetness

Column model -December

01/03/2010 HRIMeasurement of Surface Wetness

Column model -January

01/03/2010 HRI

� The functions of respective material properties used in the calculation are obtained by approximating the measured data.

Isotherm Moisture permeability

NUMERICAL ANALYSIS OF


Material Properties: Isotherm, Moisture transport coefficient, Thermal conductivity…

( )[ ]553752.1 17.0exp1443.0 hhψ −−= ( ) 78 1044.130870arctan1035.9 −− ×+−×= ψDψ( )[ ]

01/03/2010 HRI



Calculation Results

Temperature

Calculation ExperimentTim profile

3mm 12mm 400mm5mm 25mm 50mm8mm

01/03/2010 HRI


HEAT AND MOISTURE TRANSPORTCalculation Results

Temperature (26-Nov ~ 30-Nov)

Correlation diagram

3mm 12mm5mm

25mm 50mm 400mm

01/03/2010 HRI



Calculation Results

Relative humidity

Calculation ExperimentTim profile

3mm 12mm 400mm5mm 25mm 50mm8mm

01/03/2010 HRI

Relative humidity (26-Nov ~ 30-Nov)


HEAT AND MOISTURE TRANSPORTCalculation Results Correlation diagram

3mm 12mm5mm

25mm 50mm 400mm

Documents

Durable Design of Concrete -Combined Deterioration · Durable design method assuming the premeditated maintenance and repair Our research 1．Estimate of humidity distribution in