The Freeze Thaw as a Deterioration Mechanism

1
The Freeze Thaw as a Deterioration Mechanism

• This experiment is being performed to better
  understand freeze thaw cycling in order to
  prevent the resulting damage
• Necessary and Sufficient Conditions permit freeze
  thaw to initiate (Harris 02)
• Porous/ permeable material
• Water at surface
• Lateral motive force
• Conductive capillary size
• Modulus of rupture below 700psi
• Temperature falling through freezing

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Temperatures Falling Through Freezing

• This is the specific necessary and sufficient
  condition we are trying to better understand
• Our preliminary investigation suggested a
  relationship between surface temperatures and air
  temperatures
• This is a function of several conditions such as
• The amount of solar radiation, atmospheric
  condition, time of year, time of day etc
• This suggests that, in reality, building surfaces
  experience a greater number of freeze thaw cycles
  than is recorded by the monthly data.

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Average Temperatures in February for Akron, Ohio
2004
Monthly Data
Daily Data

• Average Max. Temperature (35.9)
• Average Min. Temperature (18.9)
• According to average data, everyday in February
  has the potential for freeze thaw cycling because
  air temperature fluctuated above and below
  freezing everyday

• 20 days where the max. and min. temperature
  fluctuates above and below freezing
• According to this data, 20 days in February have
  the potential for freeze thaw cycling

4
Preliminary Investigation of Taylor Hall

• Two preliminary trials of surface temperature
  readings were taken during an overcast day and a
  clear day.
• On a clear day, the temperatures on the South and
  West surfaces generally were higher than on the
  North and East.
• On the overcast day, all surface temperatures
  remained around or below the outdoor air
  temperature.
• This suggests that surface temperatures vary with
  orientation.

• Taylor Hall, Preliminary Trial
• Materials Tested
• Dark Brick e(0.93)
• Concrete e(0.85)
• Railing, Black Paint e(0.84)

North South
East West
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Actual Number of Potential Freeze Thaw Cycles

• According to the data collected from Taylor hall,
  the South and West façade materials have the
  potential to experience freeze thaw cycling on
  clear day conditions.
• Therefore, the potential number of freeze thaw
  cycles may be dictated by solar radiation.
• How can we reduce the number of freeze thaw
  cycles?
• Can we decrease the surface temperatures to
  reduce the number of freeze thaw cycles?

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Hypotheses

• The North and East surfaces will experience fewer
  temperature fluctuations (temperatures falling
  through freezing) than the South and West
  surfaces.
• We can reduce the temperature fluctuation on the
  South and West surfaces through the application
  of shading devices, decreasing their surface
  temperatures and thus reducing the potential
  number of freeze thaw cycles.

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Methods of Testing

• One week- surface temperatures at Barberton
• Use Accurite digital thermometer to measure daily
  surface temperature of the North, East, South and
  West walls at various times of the day
• Continued three week- surface temperatures at
  Barberton
• Use Accurite thermometer to measure daily MAXIMUM
  and MINIMUM surface temperatures on the North,
  East, South, and West walls.
• Ecotect simulation of solar radiation on building
  surfaces
• Determine the effects of adding a shading device
  to the building surfaces
• Cast plaster of Paris physical model simulating
  sun movement
• Use Accrurite digital thermometers cast within
  the material and affixed to exterior surfaces to
  measure surface temperature
• Use a light source, steriographic diagram

F
next
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Barberton Residence

• One story residence with basement
• 60 (East and West surfaces)
• 40 (North and South surfaces)

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Barberton Elevations
North façade, neighboring 2 story house
East façade, facing street
South façade, neighboring 1 story house
West façade, sparse deciduous
10
Barberton Floor Plan
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Barberton Clear Day Condition

• North wall has least fluctuation- West and South
  has greatest fluctuation
• Drastic increase in all surface temperatures as
  a result of clear day conditions at 300
• West wall was coolest in morning and night
• During morning, all surface temperatures near
  air temperature
• All temperatures are above freezing, shading
  device not needed

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Barberton Surface Temp Trend

• Surface temperatures follow air temperature
  unless influenced by solar radiation

13
Barberton Ideal Conditions for Added Shading
Device

• This day was all overcast with day ending with
  rain
• Surface temperatures are near or around air
  temperature
• North wall was above air temperature because of
  interior treated air
• Maximum air temperature is very close to
  freezing
• Since surface temperatures will fluctuate with
  air temperature, the ideal condition is when all
  maximum surface temperatures are above maximum
  air temperature and maximum air temperature is
  below freezing.

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Ecotect North Wall

• Insolation levels were the lowest of all
  surfaces
• Agreed with the hypothesis that the North wall
  will receive the lowest amount of solar radiation
• It was assumed that the surface temperature
  would also be low
• Using a shading device indicated little to no
  change

15
Ecotect East Wall

• Consistent with hypothesis derived from Taylor
  Hall preliminary investigation
• Evidenced an overall high level of solar
  radiation
• Shading device significantly decreased the level
  of overall insolation

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Ecotect South Wall

• Results also support the hypothesis, surface
  with the highest level of insolation
• Indicates the greatest fluctuation in incident
  solar radiation received on the surface- reaches
  each extreme
• Added shading, the surface will receive little
  to no solar radiation during clear day
  conditions, thus, reducing fluctuation in surface
  temperature
• Great potential to reduce the number of freeze
  thaw cycles

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Ecotect West Wall

• West wall will have more incident solar
  radiation than the North and East
• Solar radiation was reduced by adding a shading
  device- reaches both extremes, great potential to
  reduce the number of freeze thaw cycles
• The East and West side of a building receive
  equal amount of sunlight for half a day
  the West side will be slightly warmer than the
  East side because of the combination of solar
  radiation and higher afternoon air temperatures.
  
• (Mazria 91)

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Physical Model Construction

• 18 x 10 x 8, ¾ thick model formed with
  Styrofoam insulation and plaster of Paris
• Two Accurite thermometers cast within each wall
  halfway down and one placed on each surface
  corresponding to Barberton locations
• Plotted map of sun positions during the week
  tested in February to locate lamp position using
  the corresponding azimuth, altitude, and time of
  day

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Physical Model 3D Sun Map

• Map of sun positions
• Location of thermometers

20
Physical Model without Shade
Test position 1210 PM Altitude 9-3/4

• Lamp continuously follows path of the sun, from
  morning to night, simulating a typical day during
  the one week tested in February
• Lamp kept in each position for 10 minutes
• When finished, model was allowed to cool back to
  room temperature

Test position 350 PM Altitude 6-3/4
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Physical Model with Shade
Test position 850 AM Altitude 4-3/4

• Shades constructed of Styrofoam
• Provided shade on the majority of the surface
• Same testing procedure performed as without
  shading devices
• Shading devices on all four sides

Test position 350 PM Altitude 6-3/4
22
Physical Model with Hotplate

• Hot plate isolated to North wall simulating the
  treated air condition at Barberton
• Insulation used to separate the model in two
  distinct zones
• North zone enclosed with an Styrofoam roof
• Conclusion indicated that surface temperatures
  on North wall was significantly higher than the
  other surfaces, similar to that indicated at
  Barberton

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Physical Model Results Without Shading Device

• The model resulted in similar patterns as
  expected from hypotheses
• Similarities could also be made between the
  actual clear day condition, 02-15-05
• South wall increases at noon
• East wall peaks in morning hours
• West wall increases through the day, peaks in
  evening
• North wall remains lowest, shaded condition, and
  is relatively constant

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Physical Model with Shading/Hotplate

• All surfaces were able to be maintained with no
  fluctuation
• North wall had no change after adding shading
  device
• All surfaces temperatures did behave in the same
  manner as un-shaded but, once shaded the
  fluctuation was minimal

• All surfaces followed the same patterns as in
  previous tests except for the north wall
• The added hot plate kept the North surface
  temperature considerably higher than the others
• As the others declined, the North maintained a
  higher temperature
• Similar to night condition at Barberton

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General Assumption

• The North and East surfaces will experience fewer
  temperature fluctuations (temperatures falling
  through freezing) than the South and West
  surfaces.

Actual Number of Fluctuations at Barberton from
February 14th to March 10th North surface 13
? South surface 18 Air Temperature 11 East
surface 19 West surface 19
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Hypothesis

• We can reduce the temperature fluctuation on the
  South and West surfaces through the application
  of shading devices, decreasing their surface
  temperatures and thus reducing the potential
  number of freeze thaw cycles.
• If solar radiation It0, then surface temperature
  Ts air temp To

Example 1 February 14th at 900 AM for the East
surface q/A (aIt) (ho(to-ts) -
(eDR) Calculation 1 Solving for heat flux under
current condition q/A (0.8x26)3(46.7-45.9)-(
0) q/A 23.2 Therefore, area 200 sq.ft.
q (23.2 Btu/h.sq.ft.)(200 sq.ft.) q 4640
Btu/h Determining sol-air temperature, te to
(aIt)/ ho - (eDR)/ ho te 46.7
(0.8)(26)/3-(0/3) te 53.63 degrees
Fahrenheit Calculation 2 solving for surface
temperature by eliminating incident solar
radiation - ((q/A) (aIt) (eDR)) / ho ) to
ts - ((4640-(0.8)(26)) 0) / 3) 46.7
28.97 degrees Fahrenheit
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Hypothesis

• Surface temperature will be air temperature when
  solar radiation is zero

We can potentially reduce the actual number of
freeze thaw cycles from 13 to 1
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Hypothesis

• Surface temperature will be air temperature when
  solar radiation is zero

We can potentially reduce the actual number of
freeze thaw cycles from 19 to 6
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Hypothesis

• Surface temperature will be air temperature when
  solar radiation is zero

We can potentially reduce the actual number of
freeze thaw cycles from 18 to 5
30
Hypothesis

• Surface temperature will be air temperature when
  solar radiation is zero

We can potentially reduce the actual number of
freeze thaw cycles from 19 to 8
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Future Possibilities

• Through design, we can reduce the damage that
  results from deterioration mechanisms
• We may be able to design intelligent environments
  that respond to specific freeze thaw conditions
  that change with the temperatures and seasons
  such as removable or retractable shading device
• This may allow us to better understand
  deterioration mechanisms and the energy that they
  produce.
• Through understanding the energy of these
  mechanisms, we may potentially be able to design
  architectural systems to harness that energy.
• Perhaps deterioration can be viewed as a benefit
  as opposed to a negative impact or negotiated
  circumstance.

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Hypotheses

• The North and East surfaces will experience fewer
  temperature fluctuations (temperatures falling
  through freezing) than the South and West
  surfaces.
• We can reduce the temperature fluctuation on the
  South and West surfaces through the application
  of shading devices, decreasing their surface
  temperatures and thus reducing the potential
  number of freeze thaw cycles.