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Material performance

Amanda Palmkvist

Assignment 2Durability Modelling

Task 2.1

Simple Ficks 2nd

law model

( )DRCM=6,9*10

-12

t=time for 1, 10, 21 and 100 years in seconds

x=penetration depth (from table 3 in assignment 2 instructions)

None CRM OPC and submerged Acs,cl=10,3 (table 4.5)

Normal cost of migration of risk relative to the cost of repair c=1,4

Calculations of C were made in Matlab, the x and t value varies. Calculated values are

presented in the graph below.

( )

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Material performance

Amanda Palmkvist

Comments after comparing the measured values with the values from the field

The calculated values are higher than the measured values in the field, except from one

value. The lower values of concentration with respect to lower penetration depth, can

possibly be explained by external stress which are exposed on the element. Suggestions of

external stresses are moisture and wind.

Ingress of chloride can lead to corrosion of the reinforcement. The calculated values are

higher than the measured values. This is preferably because then action can be done beforethe concentration is too high and the reinforcement corrodes. If no action against the

corrosion is made the elements strength will decrease.

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Material performance

Amanda Palmkvist

Dura Crete Model

ke,cl=1,32 (table 4.3)

kc,cl=0,93 (interpolation with vales from table 4.1)

D0,cl=DCRM=6,9*10-12

m2/s

t0=28 days=2419200 sec

ncl=0,30 (table 4.6)

t=time for 1, 10, 21 and 100 years in seconds

x=penetration depth (from table 3 in assignment 2 instructions)

None CRM OPC and submerged Acs,cl=10,3 (table 4.5)c=1,0 (from assignment 2 instructions)

Calculations of C were made in Matlab, the x and t value varies. Calculated values are

presented in the graph below.

8/14/2019 Durability_Modelling (1).pdf

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Material performance

Amanda Palmkvist

Comments after comparing the measured values with the values from the field

The calculated values are lower and the measured values, the result is contrary to the results

from the Simple Ficks 2nd

law model. The result indicates on a higher chloride concentrationin the reality, which can lead to corrosion in an earlier stage than expected. This will

eventually also cause deformation and fracture of the element.

When ncl=0 was used the calculated values almost matched or was higher than the

measured values in the field, which is preferably in perspective of work against severe

corrosion of the reinforcement.

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Material performance

Amanda Palmkvist

Task 2.1Calculate cover thickness

Cover thickness:

g=0

The design value of the effective resistance with respect to carbonation

t=50 years = 18250 days = t0=28 days (table 5.2) (interpolation with values from table 5.1) (table 5.3)

(table 5.4)

at age 28 days

The characteristic value of the surface concentration:

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Material performance

Amanda Palmkvist

5.4)

The characteristic thickness cover is 46,7 mm