2011 APWA North American Snow & Pacific Northwest Snowfighters Conference, April 10‐12, 2011, Spokane, WAJan Olek ([email protected]) and Jason Weiss ([email protected]) , Purdue University, West Lafayette, IN
1 of 12
APWA Meeting Spring 2011 Slide 1 of 69
Prepared for the 2011 APWA North American Snow & Pacific Northwest Snowfighters Conference
April 10-12, 2011, Spokane, WA
This will be a two-part presentationPart 1 (J. Olek ) ▪ will briefly outline major challenges in the area of
accelerated testing of the effects of deicers on the ti f t
APWA Meeting Spring 2011 Slide 2 of 69
properties of concrete▪ will review the recently completed laboratory study on
the effects of magnesium and calcium chlorides on the properties of concrete
Part 2 (J. Weiss ) ▪ will review the impact of fluid transport on pavement joint
deterioration and will discuss the issues related to applicability of accelerated tests to field conditions
APWA Meeting Spring 2011 Slide 3 of 693
Jan Olek, [email protected] for the 2011 APWA North American Snow & Pacific
Northwest Snowfighters ConferenceApril 10-12, 2011, Spokane, WA
Investigate the effects of de-icing/anti-icing
chemicals on durability of concrete
E l t th h i l i t ti f d i i
APWA Meeting Spring 2011 Slide 4 of 69
Evaluate the chemical interactions of de-icing
chemicals with concrete matrix and aggregates
Compare the effects of de-icing chemicals on plain
(Type I) and fly ash (FA20) concretes
25
30
35
40
% o
f sol
ids
NaCl CaCl2 MgCl2
W/D regime F/T regime
APWA Meeting Spring 2011 Slide 5 of 69
0
5
10
15
20
1 2 2 3 4 4 Cur. 1 3 4 4 5 Cur.
Con
cent
ratio
n,
Wang et al. [1] Darwin et al. [2] Lee et al. [3] Cody et al. [4] Kozikowski et al. [5] Cur. [Current Study]
0 10 20 30 40 50 60 70
Darwin et al [2]
Lee et al. [3]
Cody et al. [4]
Temperature, oC
APWA Meeting Spring 2011 Slide 6 of 69
0 20 40 60 80 100 120 140
Current study
Wang et al. [1]
Darwin et al. [2]
Time, hours
Drying time, hours (varies from 8 to 34 hours)Wetting time, hours (varies from 16 to 132 hours)Drying Temp. , oC (varies from 23oC to 60 oC)Wetting temp. oC (varies from 4 oC to 60 oC)
2011 APWA North American Snow & Pacific Northwest Snowfighters Conference, April 10‐12, 2011, Spokane, WAJan Olek ([email protected]) and Jason Weiss ([email protected]) , Purdue University, West Lafayette, IN
2 of 12
-40 -20 0 20 40 60 80
L t l [3]
Cody et al. [4]
Current study
Temperature, oC
APWA Meeting Spring 2011 Slide 7 of 69
0 20 40 60 80 100 120 140
Wang et al. [1]
Kozikowski et al. [5]
Lee et al. [3]
Time, hours
Thawing time, hours (varies from 8 to 132 hours)Freezing time, hours (varies from 12 to 24 hours)Thawing Temp. , oC (varies from 20 oC to 58 oC)Freezing temp. oC (varies from 0 oC to -20 oC)
Previous studies utilized wide ranges of concentrations of deicers, temperature and lengths of exposure cycles; some combinations resulted in unrealistic conditions
APWA Meeting Spring 2011 Slide 8 of 69
resulted in unrealistic conditions
No prior investigations as to how accelerated testing affects the wetting and drying (or freezing and thawing) processes and thus the interaction of deicer solutions with concrete
The durability of the two types of concrete (plain and fly ash) when exposed to:
Wetting and drying (W/D) cycles
Freeze thaw (F/T) cycles
APWA Meeting Spring 2011 Slide 9 of 69
Freeze-thaw (F/T) cycles
Periodic monitoring of mass loss/ length changes and resonance frequencies of specimens exposed to W/D and F/T cycles
Determination of compressive strength of companion specimens
Cement (Type I)
Fly ash (Class C)
Air entraining agents
APWA Meeting Spring 2011 Slide 10 of 69
Air entraining agents
Deicing solutions- NaCl, MgCl2, CaCl2, Ice
Ban®
Water reducing admixtures
Coarse aggregates (limestone/ dolomite)
Mix TYPE I Mix FA 20Cement (lbs/ cu. yd) 586 470Fly ash (lbs/ cu. yd) - 117Water (lbs/ cu. yd) 246 246Fi A t (lb / d) 1303 1303
APWA Meeting Spring 2011 Slide 11 of 69
Fine Aggregates (lbs/ cu. yd) 1303 1303Coarse Aggregates (lbs/ cu. yd) 1780 1780w/cm 0.42 0.42Air Entrainer (oz. /cwt) 1.10 1.5 Water reducing admixture (oz./cwt)
6.0 3.3
Slump (in) 2.5 3.0 Air content (percent) 6.8 5.8
APWA Meeting Spring 2011 Slide 12 of 69
210 W/D cycles in 25% MgCl2
168 W/D cycles in 28% CaCl2
2011 APWA North American Snow & Pacific Northwest Snowfighters Conference, April 10‐12, 2011, Spokane, WAJan Olek ([email protected]) and Jason Weiss ([email protected]) , Purdue University, West Lafayette, IN
3 of 12
APWA Meeting Spring 2011 Slide 13 of 69
Testing ceased after 168 W/D cycles due to extensive surface deterioration.
APWA Meeting Spring 2011 Slide 14 of 69
168 W/D cycles in 28% CaCl2 210 W/D cycles in 25% MgCl2
Type IFA20
APWA Meeting Spring 2011 Slide 15 of 69
The use of fly ash helps reduce the rate of deterioration.
Type I
FA20
APWA Meeting Spring 2011 Slide 16 of 69
Light surface deterioration visible after 275 W/D cycles (64% longer than CaCl2). Testing continued until 350 W/D cycles (over 100% longer than CaCl2).
Specimens stored in calcium chloride solution exhibited significant mass loss due to severe
APWA Meeting Spring 2011 Slide 17 of 69
loss due to severe spalling of the edgesSpecimens stored in magnesium chloride solution exhibit small mass gain
Fly ash concrete specimens exhibited similar
fil i
APWA Meeting Spring 2011 Slide 18 of 69
mass profile in both solutions during their respective exposure periods.
2011 APWA North American Snow & Pacific Northwest Snowfighters Conference, April 10‐12, 2011, Spokane, WAJan Olek ([email protected]) and Jason Weiss ([email protected]) , Purdue University, West Lafayette, IN
4 of 12
Specimens exposed to calcium chloride solution exhibited early decrease in the RDME values
The RDM of specimens exposed to magnesium chloride solution started showing similar rate of
APWA Meeting Spring 2011 Slide 19 of 69
started showing similar rate of decrease in RDME but only after more than 200 W/D cycles
RDME values dropped to about 83% of the original value after about 154 cycles for specimens in CaCl2 solution and after about 350 cycles for specimens in MgCl2 solution
After the initial increase, the RDME values of FA 20 specimens exposed to calcium chloride solution started decreasing (after about 50 W/D cycles) and
h d 100% t th ti
APWA Meeting Spring 2011 Slide 20 of 69
reached 100% at the time the test was discontinued.RDME values for FA 20 specimens exposed to magnesium chloride solution remained at levels higher than 100% until the completion of the test (at about 350 cycles).
Compressive strength was measured on cylinders exposed to W/D regime after the completion of exposure in respective solutions.
APWA Meeting Spring 2011 Slide 21 of 69
The normalized compressive strength for specimens in different deicing solutions was calculated with respect to compressive strength of the specimens in deionized water.
350 cycles350 cycles 378
cycles
350 cycles168
cycles
60
80
100
120
ress
ive
stre
ngth
, %
APWA Meeting Spring 2011 Slide 22 of 69
Note: The duration of W/D cycles was 350 cycles for all specimens except for specimens in calcium chloride solution (168 cycles), and NaCl with Ice Ban® (378 cycles)
0
20
40
60
Deionized water NaCl CaCl2 MgCl2 NaCl+CaCl2 NaCl+ Ice Ban NaCl+ MgCl2
Nor
mal
ized
com
pr
Exposure solution
Type I Fly ash
APWA Meeting Spring 2011 Slide 23 of 69
extensive surface deterioration (similar to that observed during W/D exposure)
APWA Meeting Spring 2011 Slide 24 of 69
2011 APWA North American Snow & Pacific Northwest Snowfighters Conference, April 10‐12, 2011, Spokane, WAJan Olek ([email protected]) and Jason Weiss ([email protected]) , Purdue University, West Lafayette, IN
5 of 12
There is continuous increase in mass for specimens exposed to magnesium
APWA Meeting Spring 2011 Slide 25 of 69
to magnesium chloride solutionThe specimens in calcium chloride solution show continuous mass loss
FA 20 specimens in calcium chloride solution show more mass gain than
APWA Meeting Spring 2011 Slide 26 of 69
mass gain than corresponding specimens in magnesium chloride solution
Specimens show decreasing trend for RDME right after 36 cycles
APWA Meeting Spring 2011 Slide 27 of 69
Similar values of RDME after 250 cycles for Type I specimens in both solutions
The relative dynamic modulus of elasticity shows decreasing trend for FA 20
APWA Meeting Spring 2011 Slide 28 of 69
specimens in calcium chloride solution There is no such reduction for FA 20 specimens exposed to magnesium chloride solution for up to 300 cycles
APWA Meeting Spring 2011 Slide 29 of 69
In CaCl2 solution In MgCl2 solution
top surface (0 -0.5 cm) middle (~0.8-1.3 cm) bottom (~ 1.8-2.2cm)
APWA Meeting Spring 2011 Slide 30 of 69
No traces of Cl in bottom part of specimen
3CaO·Al2O3·CaCl2 · 10 H2O
2011 APWA North American Snow & Pacific Northwest Snowfighters Conference, April 10‐12, 2011, Spokane, WAJan Olek ([email protected]) and Jason Weiss ([email protected]) , Purdue University, West Lafayette, IN
6 of 12
top surface (0 -0.4 cm) middle (~0.8-1.3 cm) bottom (~ 1.8-2.2cm)
APWA Meeting Spring 2011 Slide 31 of 69
Small peak of Cl in bottom part of specimen3CaO·Al2O3·CaCl2 · 10 H2O
External signs of deterioration were more extensive in Type I specimens exposed to 168 W/D cycles in CaCl2 solution than those observed in specimens exposed to 210 W/D cycles in MgCl2 solution (despite 25% longer exposure). Initial signs of distress were observed in the MgCl2 exposed specimens only after 275 W/D cycles but even then the overall
APWA Meeting Spring 2011 Slide 32 of 69
specimens only after 275 W/D cycles but even then the overall damage was still much less than that observed in the CaCl2specimens after 168 W/D cycles (60% shorter exposure).Surface deterioration of Type I specimens exposed to the MgCl2 solution for 350 W/D cycles was observed to be comparable to the surface deterioration of the equivalent specimens in the CaCl2 for 168 W/D cycles. This indicates the specimens in the CaCl2 were deteriorating at the rate at least twice as fast as the specimens in the MgCl2 solution.
The RDME values of the specimens exposed to MgCl2stayed at the 100% level for almost 200 W/D cycles as opposed to about 30 cycles for specimens exposed to the CaCl2. This indicates that the CaCl2 solutions
l t th d t i ti t t i t l 3
APWA Meeting Spring 2011 Slide 33 of 69
accelerate the deterioration rate to approximately 3 times that of the MgCl2 solutions.
The fly ash concrete demonstrates better performance compared with the Type I specimens.
APWA Meeting Spring 2011 Slide 34 of 69
Jason Weiss, [email protected] for the 2011 APWA North American Snow & Pacific
Northwest Snowfighters ConferenceApril 10-12, 2011, Spokane, WA
Motivation for Research
Damage is seen in the transverse and longitudinal joints in many pavements.
APWA Meeting Spring 2011 Slide 35 of 39
Some have related this entirely to de-icers.
Is this fair or are there other factors?
Pavement Joint Deterioration
• Deterioration of pavement joints has caused many to question the cause of this distress
• Many have sought to explain with:– Poor Air Entrainment
APWA Meeting Spring 2011 Slide 36 of 39
– Poor Air Entrainment– Poor Construction– Design Changes– New Deicing Practices– New Deicing Materials
• However closer examination is needed
2011 APWA North American Snow & Pacific Northwest Snowfighters Conference, April 10‐12, 2011, Spokane, WAJan Olek ([email protected]) and Jason Weiss ([email protected]) , Purdue University, West Lafayette, IN
7 of 12
Joint Details
• Joints are placed in concrete pavements to control shrinkage and thermal cracking
• The joint is designed to crack thereby relieving stress in the pavement
APWA Meeting Spring 2011 Slide 37 of 39
relieving stress in the pavement• Typically a single cut is placed to 1/3 of the
depth of the pavement at early age • After cracking a second cut is made • To keep water and incompressibles out of
the joint sealant is placed in the joint
An Ideal Longitudinal Joint
Water-Salt Solution2nd Cut
APWA Meeting Spring 2011 Slide 38 of 39
Weiss and Nantung 2005
Joint Sealant
Backer Rod
Initial Cut
Crack
Less ideal case – Damaged seal
Water-Salt Solution2nd Cut
APWA Meeting Spring 2011 Slide 39 of 39
Weiss and Nantung 2005
Joint Sealant(Failed)
Backer Rod
Initial Cut
Crack
The least ideal case – No Crack
Water-Salt Solution2nd Cut
APWA Meeting Spring 2011 Slide 40 of 39
Weiss and Nantung 2005
High Degree of Saturation Zone
Initial Cut
Damaged Retention
Hypothesis for Saturation and Damage in Joints
• Fluid entering joint is trapped• Saw cut joints are
not opening • As a result, fluid
APWA Meeting Spring 2011 Slide 41 of 39
As a result, fluid can not drain out to drainable sub-base under the PCCP
• Silicone sealant and backer rod limit drying of trapped water Weiss and Nantung 2005
Weiss and Nantung 2005
Why be concerned about fluid ingress
PoorD bilit
Good Durability
to F
rost
(%) 100
80
60Poor
D bilit
Good Durability
to F
rost
(%) 100
80
60
APWA Meeting Spring 2011 Slide 42 of 39
Durability
Degree of Saturation (%)60 65 70 75 80 85 90 95 100
Res
ista
nce
t
40
20
0
After CEB 1957
Durability
Degree of Saturation (%)60 65 70 75 80 85 90 95 100
Res
ista
nce
t
40
20
0
After CEB 1957
There is a critical saturation that makes concrete
susceptible to repeated F-T
2011 APWA North American Snow & Pacific Northwest Snowfighters Conference, April 10‐12, 2011, Spokane, WAJan Olek ([email protected]) and Jason Weiss ([email protected]) , Purdue University, West Lafayette, IN
8 of 12
Influence of Paste Porosity
6.0
7.0
8.0
orpt
ion
/mm
2 )
50%RH65%RH80%RHStandard Cond.
• High w/c mixes absorb more water faster than low w/c mixes
12.0
14.0
16.0
tion
5 )
50%RH65%RH80%RHStandard Cond.
APWA Meeting Spring 2011 Slide 43 of 39
0.30 0.35 0.40 0.45 0.50 0.55water/cement
0.0
1.0
2.0
3.0
4.0
5.0
Cum
ulat
ed A
bso
at 8
day
s (m
m3 /
0.30 0.35 0.40 0.45 0.50 0.55water/cement
0.0
2.0
4.0
6.0
8.0
10.0In
itial
Abs
orpt
(10-3
mm
/s0.
Note: Standard conditioning from saturation
Degree Of Saturation and Air Content
• Once saturated all concrete fails
• Entrained air alters time to DOS but not
0.20
0.40
0.60
0.80
1.00
E/E 0
M-6N=0N=1N=2N=3N=4
APWA Meeting Spring 2011 Slide 44 of 39
the occurrence
Li et al. to be published 2010
75 80 85 90 95 100Degree of Saturation (%)
0.00
N=5N=6
Times to Reach 92% DOS
• 50% Relative Humidity – 0.4 years 4% Equivalent Concrete Air– 6.1 years 6.5% Equivalent Concrete Air– 5.8 years 9% Equivalent Concrete Air
• 65% Relative Humidity
Li et al. to be published 2010
APWA Meeting Spring 2011 Slide 45 of 39
65% Relative Humidity – 0.5 years 4% Eq. Air– 2.6 years 6.5% Eq. Air– 9.6 years 9% Eq. Air
• 80% Relative Humidity – 0.3 years 4% Eq. Air– 5.9 years 6.5% Eq. Air– 6.3years 9% Eq. Air
The Drive for Fast Results
• We can not wait 10 to 20 years to see if a pavement may be susceptible to damageA lt l t d
APWA Meeting Spring 2011 Slide 46 of 39
• As a result accelerated tests are developed to rapidly provided feedback on how damage develops and how this is related to the mixture
Do Accelerated TestsAccurately Represent this Issue
• Do they provide an indication of the real life damage that occurs ?
• Do they examine actual mechanisms or do they create alternate damage ?
APWA Meeting Spring 2011 Slide 47 of 39
• Are there shortcomings ?• What time scaling functions should be used ?• Can they mislead ?• Well intentioned but may not be thought through• Will not touch on possible reactions today
Outline
• Concrete Pavement Joints – A Review of Common Construction Practices
• A Discussion of Partial Saturation and Why it is Important for this Problem
APWA Meeting Spring 2011 Slide 48 of 39
it is Important for this Problem• Accelerated Tests and Some Issues that
Arise that Should be Remembered• These Test Details are Crucial when One
Interprets Tests Reported by Different Research Programs
2011 APWA North American Snow & Pacific Northwest Snowfighters Conference, April 10‐12, 2011, Spokane, WAJan Olek ([email protected]) and Jason Weiss ([email protected]) , Purdue University, West Lafayette, IN
9 of 12
Important Issue #1
• Accelerated testing can change the mechanics of the problem
• Accelerated test can trigger something different than what is seen in field conditions
• When this happens ‘scaling results’ in terms of
APWA Meeting Spring 2011 Slide 49 of 39
When this happens scaling results in terms of time is very difficult
• Accelerated testing should not just tell if something happens but when.
• Some aspects of what people are seeing may occur 80 years in the future.
A Brief Discussion of Mechanisms of Fluid Transport
• Concrete is a porous material (wide range of sizes, pores like to be wet)
• Desorption (drying) – water leaves (slow)• Absorption (unsat.) – fluid ingress (fast)
APWA Meeting Spring 2011 Slide 50 of 39
p ( ) g ( )• Diffusion (sat.) – species gradient (slow)• Wick
Important Issue #2
• Accelerated testing can change the boundary conditions of the problem
• Accelerated test can trigger something different than what is seen in field conditions
APWA Meeting Spring 2011 Slide 51 of 39
different than what is seen in field conditions• This causes different driving forces than
what occurs in the problem
Accelerated Testing
• Some pushing for “fast” tests, but what do they represent
MicrocracksFluidVapor
APWA Meeting Spring 2011 Slide 52 of 39
80% RH
Oven Dry
FluidVapor
Actual RHIn Pavement
• RH in field concrete is very high
• Implication only a thin skin dries if any (absorption) while core
11/1/09 12/1/09 1/1/10 2/1/10 3/1/10 4/1/10 5/1/1075
80
85
90
95
100
Rel
ativ
e H
umid
ity (%
)
-10.0
0.0
10.0
20.0
30.0
Tem
pera
ture
(C)
12 mm RH25 mm RH50 mm RH92 mm RH
Covered Slab
Kompare et al. to be published 2010
APWA Meeting Spring 2011 Slide 53 of 39
(absorption) while core remains mostly saturated (diffusion)
• In joints little drying as sealant traps water
11/1/09 12/1/09 1/1/10 2/1/10 3/1/10 4/1/10 5/1/1075
80
85
90
95
100
Rel
ativ
e H
umid
ity (%
)
-10.0
0.0
10.0
20.0
30.0
Tem
pera
ture
(C)
12 mm RH
Submerged
Note: It is believed the slabs were not submerged after March
Absorption vs. Conditioning
• Samples stored at a low RH absorb more fluid [Castro et al.2010]
• Microcraking
8
10
12
on (m
m3 /m
m2 )
w/c = 0.45, Oven Dryw/c = 0.45, 50% RHw/c = 0.45, 65% RHw/c = 0.45, 80% RH
c)
APWA Meeting Spring 2011 Slide 54 of 39
• Microcraking opens paths
• Makes sense as more pore space is open however it is not the critical factor (index)
0 20 40 60 80 100Time (days)
0
2
4
6
Wat
er A
bsor
ptio
2011 APWA North American Snow & Pacific Northwest Snowfighters Conference, April 10‐12, 2011, Spokane, WAJan Olek ([email protected]) and Jason Weiss ([email protected]) , Purdue University, West Lafayette, IN
10 of 12
Important Issue #3
• Some tests are being used without a full appreciation of what parameters are important
• Here we will talk about a test that measures
APWA Meeting Spring 2011 Slide 55 of 39
Here we will talk about a test that measures rate….. While rate is one component it is really not the most important rather what we want is “how close are we to the end”
• While many are measuring the rate of absorption. Degree Of Saturation is what drives the Freeze-Thaw process
Good Durability (%) 100
Good Durability (%) 100
Degree of Saturation
• What is important is the volume of pores that are filled/the volume available (Degree of saturation)
• Freeze-thaw damage requires a critical degree ofsaturation (75 90%
APWA Meeting Spring 2011 Slide 56 of 39
PoorDurability
Good Durability
Degree of Saturation (%)60 65 70 75 80 85 90 95 100
Res
ista
nce
to F
rost 80
60
40
20
0
After CEB 1957
PoorDurability
Good Durability
Degree of Saturation (%)60 65 70 75 80 85 90 95 100
Res
ista
nce
to F
rost 80
60
40
20
0
After CEB 1957
There is a critical saturation that makes concrete
susceptible to repeated F-T
(75-90% from literature)
• Mixture dependent
Absorption vs Degree of Saturation
• Absorption less important than DOS saturation• Harder to saturate ‘wet concrete’ [Castro et al. 2010]
0.8
1.0
on
10
12
3 /mm
2 ) c)
APWA Meeting Spring 2011 Slide 57 of 39
0 20 40 60 80 100Time (days)
0.0
0.2
0.4
0.6
0.8
Deg
ree
of S
atur
atio
w/c = 0.45, Oven Dryw/c = 0.45, 50% RHw/c = 0.45, 65% RHw/c = 0.45, 80% RH
c)
0 20 40 60 80 100Time (days)
0
2
4
6
8
Wat
er A
bsor
ptio
n (m
m3
w/c = 0.45, Oven Dryw/c = 0.45, 50% RHw/c = 0.45, 65% RHw/c = 0.45, 80% RH
Important Issue #4
• Improper conclusions can be drawn if all the details are not considered
• Many studies are pulling field cores for example and performing absorption tests
APWA Meeting Spring 2011 Slide 58 of 39
example and performing absorption tests• Using tests data
to infer items aboutchanges in the materialstructure
• DangerousA
bsor
ptio
n
Square Root of Time
Pristine
Exposed to Salt
Important Issue #4
• The presence of deicing salts in the field samples impacts the absorption
• Many mistakenly identify this as damage or Pristine
APWA Meeting Spring 2011 Slide 59 of 39
this as damage or ‘pore filling’
• Care must be taken in analyzing field concrete exposed to deicing salt solutions
Abs
orpt
ion
Square Root of Time
Pristine
PreviouslyExposed to Salt
Important Issue #4
• Deicing solutions reduce the rate of fluid absorption [Hall and Hoff, 2002]
0.8
1.0
1.2
/ (γ/η)
0.5 w
ater
NaCl theoretical
APWA Meeting Spring 2011 Slide 60 of 39
2002]
0 10 20 30 40Concentration (Mass %)
0.2
0.4
0.6
(γ/η
)0.5 so
lutio
n NaCl theoreticalNaCl measuredNaCl relative sorptivityCaCl2 theoreticalCaCl2 measuredCaCl2 relative sorptivityMgCl2 theoreticalMgCl2 measured
MgCl2 relative sorptivity
Spragg et al. 2010
2011 APWA North American Snow & Pacific Northwest Snowfighters Conference, April 10‐12, 2011, Spokane, WAJan Olek ([email protected]) and Jason Weiss ([email protected]) , Purdue University, West Lafayette, IN
11 of 12
Important Issue #5
• Moisture history influences the absorption properties of the concrete (Hystersis)
• Here – Drying followed by ASTM standard
8
10
mm
2 )
w/c = 0.40, 50%RH + Standard cond.w/c = 0.40, 65%RH + Standard cond.w/c = 0.40, 80%RH + Standard cond.
APWA Meeting Spring 2011 Slide 61 of 39
by ASTM standard • Saturation is suggested
for beginning test• Tests of field or oddly
conditioned samplescan be very suspect 0 2 4 6 8 10
Time (days)
0
2
4
6A
bsor
ptio
n (m
m3 /m w/c = 0.40, Pre-Sat. + Standard cond.
Important Issue #6
• Drying and wetting are different• Overly severe drying (low RH) unfairly treats
the salt solutions • The system with the salt never ‘dries’ while
APWA Meeting Spring 2011 Slide 62 of 39
ythe reference does (all depends on conc and boundary conditions)
• Salt solutions are in equilibrium at lower RH than water as such they evaporate less
• As mentioned field cases are wet the majority of the time in the joints
“Drying of Concrete with Deicers”
0.4
0.2
0.0
-0.2
f Wat
er L
oss
/ mm
2 of s
urfa
ce)
0 10 20 30 40Concentration (Mass %)
0
20
40
60
80
100
RH
(%)
NaClCaCl2MgCl2 (c)
APWA Meeting Spring 2011 Slide 63 of 39
Spragg et al. submitted 2010
1.0
0.8
0.6
Volu
me
of(m
m3 o
f wat
er
0 24 48 72 96 120 144 168 192 216
Time (h)
DI WaterMgCl2 0.9%MgCl2 30%CaCl2 0.96%CaCl2 32%NaCl 0.7%NaCl 23%
Illustration of Importance
• Wetting and drying illustration for water and deicing solution
et
With DeicersCritical DOS
APWA Meeting Spring 2011 Slide 64 of 39
• Exasterbated with excessive drying
Dry
W
e
Water
Important Observation #7
• The time scale differs between drying and wetting – Drying takes a much longer time
0.0
-0.2
Loss
f sur
face
)
8
10
on
f sur
face
)
1 Week of Drying
APWA Meeting Spring 2011 Slide 65 of 39
• Many strategies do not appear to scale
1.0
0.8
0.6
0.4
0.2
Volu
me
of W
ater
L(m
m3 o
f wat
er /
mm
2 of
0 24 48 72 96 120 144 168 192 216
Time (h)
DI WaterMgCl2 0.9%MgCl2 30%CaCl2 0.96%CaCl2 32%NaCl 0.7%NaCl 23%
0 2 4 6 8 10Time (days)
0
2
4
6
Wat
er A
bsor
ptio
(mm
3 of w
ater
/ m
m2 of
65% paste volume55% paste volume45% paste volume
1 Week of Drying
Hrs of wetting
Important Issue #7 - Viscosity
(a) Horizontal and (b) vertical ingress in cement paste
APWA Meeting Spring 2011 Slide 66 of 39
2011 APWA North American Snow & Pacific Northwest Snowfighters Conference, April 10‐12, 2011, Spokane, WAJan Olek ([email protected]) and Jason Weiss ([email protected]) , Purdue University, West Lafayette, IN
12 of 12
Viscosity Measurements
• Viscosity effects transport • Penetration as well
1
10
100
s)
SME-PS Blends, 25OCWater, 25OC
0 10 20 30 40
1
10
100
APWA Meeting Spring 2011 Slide 67 of 39
0 10 20 30 40Polystyrene Content (%)
0.0001
0.001
0.01
0.1
Visc
osity
(Pa
-
0.0001
0.001
0.01
0.1
Summary of Saturation in Joint
• Water entering joints, particularly longitudinal saw joint, is trapped
• Longitudinal saw cut joints not cracking or if cracking not opening
APWA Meeting Spring 2011 Slide 68 of 39
• As a result, water can not drain out to drainable sub-base under PCCP
• Silicone sealant and backer rod limit evaporation/drying of trapped water
• Higher w/c mixtures are more susceptible to damage than low w/c mixtures
Summary
• Tried to review issues in many tests• Mechanism (sorption, drying, diffusion)• Importance of boundary conditions
Ab ti t d f t ti
APWA Meeting Spring 2011 Slide 69 of 39
• Absorption rate versus degree of saturation• Errors when testing field samples (presence
of salts, moisture history) • Importance of drying versus wetting time
scales and boundary conditions• Must consider in evaluating data