A presentation given at the 39th Annual NCPA Concrete Paving Workshop. By Larry Sutter, PhD., P.E., FACI, Michigan Technological University

1. Update on Deicer Distress
Larry Sutter Ph. D., P.E., FACI
Michigan Technological University
Material Science& Engineering

4. Outline
• Background
• A little theory
• Discuss the causes
• Discuss some solutions

5. Wisconsin

6. Wisconsin

7. Wisconsin

9. Michigan

10. Michigan

11. Wisconsin

12. Michigan
I-275

13. Michigan
I-94

14. Michigan
I-94

16. Material Science & Engineering

17. Material Science & Engineering
Premature Joint Deterioration

18. Many Suspects
• Air entraining agents
• Early entry sawing
• Curing
• Deicing practices

19. What Do We Know?
• We understand the causes
–Physical Attack (factors: permeability)
• Saturated paste localized at joints
• Freeze-Thaw deterioration located at joints
–Chemical Attack (factors: permeability, CaOH)
• Oxychloride formation – paste deterioration

20. Physical Attack
• Concrete is a porous material – water
goes in, out and is absorbed
• Durability is achieved through reduced
permeability
• Porosity (permeability) is a result of:
– The cement hydration process
– Other materials used (aggregates)
Materials Science & Engineering

21. Cement Hydration
Cement Grains
Water

22. Cement Hydration
Early Hydration Products

23. Later Hydration Products or “Outer Product”
Cement Hydration
Hydration
products are
porous (gel
pores) causing
permeability at
a nano-scale

24. Inner Hydration
Product
Unhydrated Cement
Hydrated Portland Cement Paste
Capillary Pores
(nano - microns)
Outer Hydration Product
Gel Pores
(nano scale)
Entrained Air Voids
(microns - millimeters)

26. Capillary Pores
CSH
Framework
Neville
High Permeability
(Capillary Pores Interconnected)

27. Capillary Pores
CSH
Framework
Low-Permeability Capillary Pores
Segmented and Only Partially Connected
Neville

28. Mindess & Young
Porosity & Permeability
Connectivity
0.45 w/c
45% connected at 75%
hydration
0.60 w/c
90% connected at 75%
hydration

29. Mindess & Young
Porosity & Permeability
Permeability

30. w/c Effects on Permeability
ASTM C1585
0.55 w/c OPC Sorptivity 0.45 w/c OPC Sorptivity
Materials Science & Engineering

31. Inner Hydration
Product
Unhydrated Cement
Hydrated Portland Cement Paste
Capillary Pores
(nano - microns)
Outer Hydration Product
Gel Pores
(nano scale)
Entrained Air Voids
(microns - millimeters)

32. Air-Void System
Materials Science & Engineering

34. Hydraulic Pressure Theory – Powers 1945
Attributed damage to
excessive hydraulic
pressures resulting from
the expansion of ice
Materials Science & Engineering

35. Hydraulic Pressure Theory – Powers 1945
• Water fills capillary pore space
Materials Science & Engineering
air voids
capillary voids

36. Hydraulic Pressure Theory – Powers 1945
• Ice begins to form in a saturated capillary pore system
Materials Science & Engineering

37. Hydraulic Pressure Theory – Powers 1945
• As ice forms - volume expansion causes the unfrozen water to
be expelled away from the freezing sites
Materials Science & Engineering

38. Hydraulic Pressure Theory – Powers 1945
• Depending on the nature of the pore system, excessive internal
stresses result from resistance to this flow
Materials Science & Engineering

39. Hydraulic Pressure Theory – Powers 1945
• The pressurized water moving away from the freezing sites finds
relief at the air voids, where it freezes without causing damage
Materials Science & Engineering

40. Hydraulic Pressure Theory – Powers 1945
• Powers recognized the spacing between voids, rather than total
volume of air, was the better measure of resistance to F-T
damage
Materials Science & Engineering

41. Hydraulic Pressure Theory – Powers 1945
• If the total void system is saturated...
Materials Science & Engineering

42. Hydraulic Pressure Theory – Powers 1945
• Volume expansion leads to tensile forces and cracking
Materials Science & Engineering

43. • Water moves through concrete under pressure
– Hydraulic Pressure; Osmotic Pressure
• Resistance to flow and expansive forces cause tensile
forces in concrete
• Air voids relieve the pressure – need an adequate air
void system
• Big Two affecting permeability – w/c and curing
• Dissolved salts affect the fluids (to be discussed more)
Materials Science & Engineering
Take Aways – Pore Structure

44. S
Poor
Durability
Good Durability
Degree of Saturation (%)
60 65 70 75 80 85 90 95 100
ResistancetoFrost(%)
100
80
60
40
20
0
After CEB 1957
Poor
Durability
Good Durability
Degree of Saturation (%)
60 65 70 75 80 85 90 95 100
ResistancetoFrost(%)
100
80
60
40
20
0
After CEB 1957
There is a critical
saturation that
makes concrete
susceptible
to repeated F-T
So what does this have to do
with joint distress?
• Mechanism
– Results when the paste becomes “critically saturated” and
concrete under goes F-T cycles
– The expansion of ice causes tensile forces that crack concrete
Figure from J. Weiss

45. Deicers and Sealers January 16th, 2012 Slide 45 of 1,348
Freeze-Thaw Damage and
the Degree of Saturation
• Rate to reach DOS
• FT at different DOS

46. Take Aways - Paste F-T
• Concrete porosity cannot be avoided
• Concrete porosity (permeability) is directly
linked to w/cm and curing (connectivity)
• Air is entrained to protect the paste – but it
is not a bullet-proof solution
– Critically saturated paste will crack when frozen
• Need proper air content and air-void system
(spacing factor, specific surface)

47. Take Aways - Paste F-T
• Do deicers play a role in physical attack?
• YES

48. Take Aways - Paste F-T
• Salts
suck up
water &
hold it
• Helps
concrete
reach
saturation
sooner
Photos courtesy Peter Taylor, Iowa State University

49. • Residual salt in the pore structure imbibes
and holds water
• The concrete does not completely “dry”
out in drying conditions
• Retained moisture incrementally increases
the concrete moisture content and reduces
the time to reach critical saturation
Take Aways - Paste F-T

50. What Do We Know?
• We think we understand the causes
–Physical Attack
• Saturated paste localized at joints
• Freeze-Thaw deterioration located at joints
–Chemical Attack from deicers
• Oxychloride formation – paste deterioration

51. Cylinders exposed to MgCl2 solution after 84 days of constant low
temperature test. From left to right: 0.40, 0.50, and 0.60 w/c

52. Cylinders exposed to CaCl2 solution after 84 days of constant low
temperature test. From left to right: 0.40, 0.50, and 0.60 w/c

53. Cylinders exposed to NaCl solution after 84 days of constant low
temperature test. From left to right: 0.40, 0.50, and 0.60 w/c

54. Cylinders exposed to Ca(OH)2 solution after 84 days of constant low
temperature test. From left to right: 0.40, 0.50, and 0.60 w/c

55. Hi conc. CaCl2 – 500 days – 40 ºF

56. Hi conc. MgCl2 – 500 days – 40 ºF

57. Chemical Mechanisms of Deicer
Attack How Calcium Chloride (CaCl2) Attacks
3Ca(OH)2 + CaCl2 + 12H2O  3CaO·CaCl2·15H2O
 How Sodium Chloride (NaCl) Attacks
2NaCl + Ca(OH)2  CaCl2 + 2NaOH
 How Magnesium Chloride (MgCl2) Attacks
Ca(OH)2 + MgCl2  CaCl2 + Mg(OH)2
C-S-H + MgCl2  CaCl2 + M-S-H
Calcium Oxychloride

58. Chemical Mechanisms of Deicer
Attack How Calcium Chloride (CaCl2) Attacks
3Ca(OH)2 + CaCl2 + 12H2O  3CaO·CaCl2·15H2O
 How Sodium Chloride (NaCl) Attacks
2NaCl + Ca(OH)2  CaCl2 + 2NaOH
 How Magnesium Chloride (MgCl2) Attacks
Ca(OH)2 + MgCl2  CaCl2 + Mg(OH)2
C-S-H + MgCl2  CaCl2 + M-S-H
Calcium Oxychloride

59. Chemical Mechanisms of Deicer
Attack How Calcium Chloride (CaCl2) Attacks
3Ca(OH)2 + CaCl2 + 12H2O  3CaO·CaCl2·15H2O
 How Sodium Chloride (NaCl) Attacks
2NaCl + Ca(OH)2  CaCl2 + 2NaOH
 How Magnesium Chloride (MgCl2) Attacks
Ca(OH)2 + MgCl2  CaCl2 + Mg(OH)2
C-S-H + MgCl2  CaCl2 + M-S-H
Calcium Oxychloride

60. Chemical Mechanisms of Deicer
Attack How Calcium Chloride (CaCl2) Attacks
3Ca(OH)2 + CaCl2 + 12H2O  3CaO·CaCl2·15H2O
 How Sodium Chloride (NaCl) Attacks
2NaCl + Ca(OH)2  CaCl2 + 2NaOH
 How Magnesium Chloride (MgCl2) Attacks
Ca(OH)2 + MgCl2  CaCl2 + Mg(OH)2
C-S-H + MgCl2  CaCl2 + M-S-H
Calcium Oxychloride
Left of arrow – Reactants
Right of arrow – Products
Products occupy larger volume
than reactants! EXPANSIVE!

61. Chemical Mechanisms of Deicer
Attack How Calcium Chloride (CaCl2) Attacks
3Ca(OH)2 + CaCl2 + 12H2O  3CaO·CaCl2·15H2O
 How Sodium Chloride (NaCl) Attacks
2NaCl + Ca(OH)2  CaCl2 + 2NaOH
 How Magnesium Chloride (MgCl2) Attacks
Ca(OH)2 + MgCl2  CaCl2 + Mg(OH)2
C-S-H + MgCl2  CaCl2 + M-S-H
Calcium Oxychloride

62. Chemical Mechanisms of Deicer
Attack How Calcium Chloride (CaCl2) Attacks
3Ca(OH)2 + CaCl2 + 12H2O  3CaO·CaCl2·15H2O
 How Sodium Chloride (NaCl) Attacks
2NaCl + Ca(OH)2  CaCl2 + 2NaOH
 How Magnesium Chloride (MgCl2) Attacks
Ca(OH)2 + MgCl2  CaCl2 + Mg(OH)2
C-S-H + MgCl2  CaCl2 + M-S-H
Calcium Oxychloride

63. New Work - Purdue
• The solutions that freeze are not a mixture of
salt and water (a) – there are alkalis and other
species in the solution (b)
Farnam Y., S Dick, A Wiese, J Davis, D Bentz, J Weiss. “The Influence of Calcium Chloride
Deicing Salt on Phase Changes and Damage Development in Cementitious Materials.”
Cement and Concrete Composites, Volume 64, November 2015, Pages 1-15.

64. Calcium Oxychloride
Farnam Y., S Dick, A Wiese, J Davis, D Bentz, J Weiss. “The Influence of Calcium Chloride
Deicing Salt on Phase Changes and Damage Development in Cementitious Materials.”
Cement and Concrete Composites, Volume 64, November 2015, Pages 1-15.
Calcium oxychloride and brine solution

65. Oxychloride Formation
• Work at Michigan Tech and now confirmed at
Purdue shows oxychloride forms at
temperatures above freezing
• Implications – residual salt in concrete pore
structure will form oxychloride – chemical attack
year round ????
• To what extent is this happening ????

66. Take Aways – Chemical Attack
• Brines of magnesium and calcium chloride
have been demonstrated to react
deleteriously with hydrated cement paste
– Expansive calcium oxychloride forms
– Reaction is slower than physical attack
mechanisms
– Reaction may occur year round

67. What do we do?
• Reduce permeability
• Use SCMs
• Drainage

68. Reduce Permeability
• Keep the water out and reduce the salt
brine ingress
– Lower w/cm (0.40 or less)
– Need functioning sealants
– Penetrating sealers
– Permeability reducing admixtures
– Use SCMs

69. D1 0980-127
1992

70. D1 0980-127
1992
Silicone sealant completely de-bonded.
Severe joint distress.

71. D1 3805-67 (TH61)
Sealant Bonded
1997

72. D1 3805-67 (TH61)
Sealant bonded both sides, pristine
joint crack

73. D3 7380-199
1999
Well bonded

74. D3 7380-199
Silicone sealant well bonded both sides.
LATE, pristine crack

75. A word on sealers...
• Silane and siloxane are effective at
reducing the ingress of fluid into concrete

76. A word on sealers...
• Silane and siloxane are effective at
reducing the ingress of fluid into concrete
• Questions?
– How long do they last?
– F-T durability of the sealer?
– Cost effectiveness compared to other options?
– Can you get it where you need it (in the joint)?

77. Salt Ingress for OPC mixture

78. PCC Mixtures
Tri-siloxane 12% (aliphatic hydrocarbon)

79. Permeability Reducing Admixtures
• Different types – different mechanisms
– Water repellents
– Crystal formers
– Colloidal silica/silicates
• Need more research
• Similar questions to sealers
• MiDOT research – Phase I completed
– Durability testing included

80. Deicer Resistance in 17% CaCl2

81. Primary and Secondary Sorptivity
ASTM C1585

82. SCMs
• Oxychloride requires calcium hydroxide (CH) to form
• Reduce the CH – reduce oxychloride formation
Portland Cement Reaction
Cement + Water -> C-S-H + CH
Pozzolanic Reaction (example: Class F Fly Ash)
CH + Pozzolan + Water -> C-S-H
• Forming C-S-H reduces permeability
• Consuming CH reduces oxychloride formation

83. Sorptivity of 15% MgCl2 into
Different 0.45 w/c Concrete Mixtures
Materials Science & Engineering
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 200 400 600 800 1000
Absorption[I](mm)
Time (s1/2)
OPC
fly ash
slag

84. Take Aways – Actions
• SCMs, reduced w/cm, and proper curing
are the best options
• Sealants can be effective – we still do not
have a good way to install
• PRAs offer opportunity – more research is
needed
– Cost is a key factor

85. Take Aways – Actions
• Use of SCMs reduces susceptibility of
concrete for chemical attack
– Reduces CH available to react
– Permeability of concrete not compromised by
CH leaching
– Improves concrete strength (affects physical
and chemical attack)

86. Summary
• Keep fluids out of concrete and all materials-
related distress is minimized
• Materials selection is very important
– Low w/c
– Low paste content
– Use SCMs
• Curing is essential
– Keep the mixture water in and allow the materials
time to form dense, impermeable, hydration products

87. Summary
• Deicing chemicals are a serious concern
– Contribute to physical attack
– Contribute to chemical attack
• Sealers may be required to offset deicing
fluids
– Keep brines out
– Slow ingress of salt solutions

88. Questions?
Larry Sutter
llsutter@mtu.edu