Post on 14-Jun-2015
American Concrete Institute on the durability of concrete
ACI Quote: “From the materials standpoint, concrete durability is closely linked to concrete microstructure, more specifically to its impermeability.”
Concrete Ingredients:
Portland Cement Water Coarse & Fine
Aggregates Admixtures
Water-Friend AND Foe
Water in USG
0
5
10
15
20
25
30
35
Hydration Water
Free Water
Mix Water
Portland Cement Components:
Tricalcium silicate = 50% Dicalcium silicate = 25% Tricalcium aluminate = 10% Tetracalcium aluminoferrite = 10% Gypsum = 5%
Concrete’s strength is the result of 5 chemical reactions here are 2:Tricalcium silicate + water = calcium silicate hydrate + calcium hydroxide (provides early strength, 7 days) + HeatDicalcium silicate + water = calcium silicate hydrate + calcium hydroxide (provides long term strength, 28 days) + Heat
Water-Friend AND Foe
Wa-ter in
USG
0
5
10
15
20
25
30
35
Free Wa-ter
Mix Water
“Water in concrete becomes an accounting problem—when designing a mix you must know how much water is present and where it all goes. Some is consumed by the cement hydration process, some escapes into the air, some may be absorbed by the ground (if there is no vapor retarder), and some resides in the coarse aggregate. To reduce drying time, mix water must either leave a slab or be chemically or physically bound as quickly as possible.”
Kevin MacDonald, vice president of engineering services for Cemstone, Mendota Heights, MN
Capillary Formation Bleed ChannelsRoute of Moisture Vapor Emission Heavier Materials Settle Water is Pushed out, Bleed Channels Free Water/Moisture Vapor Emission has
Perfect Path to Follow External Intrusion-Perfect Path
Capillary Action
Moisture \Vapor is released by way of the capillary system
Moisture \Vapor can travel into and out of the concrete through the capillary system
Capillaries Vapor Emission
Components: Tricalcium silicate = 50% Dicalcium silicate = 25% Tricalcium aluminate = 10% Tetracalcium aluminoferrite = 10% Gypsum = 5%
WVRA creates the additional CSH needed to: Eliminates the effects of the “free water” Close the capillary system
Solution-Concrete Chemistry
Tricalcium silicate + Mix Water = calcium silicate hydrate (CSH) + calcium hydroxideDicalcium silicate + Mix Water = calcium silicate hydrate (CSH) + calcium hydroxideWater Vapor Reducing (WVRA) admixture + Free Water = calcium silicate hydrate gel (CSH)
CSH Formation
FREEWATER
+ = Calcium Silicate Hydrate (CaSi02)
WVRA
Product cm/s Perms Constant
WVRA5.17E-
11 0.00095.728E-
08
Quality VB2.119E-
09 0.0375.728E-
08Cementitious
Patch6.301E-
09 0.115.728E-
08
Epoxy Topical3.036E-
08 0.535.728E-
08
Internally Ionic Bonded
5.662E-10 0.010
5.728E-08
WVRA
Qualit
y VB
Cemen
titio
us P
atch
Epoxy
Top
ical
Inte
rnal
ly Io
nic Bon
ded
0.00E+00
1.00E-01
2.00E-01
3.00E-01
4.00E-01
5.00E-01
6.00E-01
cm/sPermsConstant
ACI Quote: “From the materials standpoint, concrete durability is closely linked to concrete microstructure, more specifically to its impermeability.”
Benefits of WVRA in Concrete
• Impermeability
Topical Moisture Solution?
ASTM E-960
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Topical ATopical BWVRA
Flooring Solution Comparison
WVRA Topical Epoxies
Pro-active No VOC’s Warranted
Labor & Material 10 years
No Project Delays Inexpensive ($0.50-
$0.75 sf) Improves IEQ
Reactive VOC’s Warranted
Labor & Material
Massive Project Delays
Expensive ($3-$8 sf) Erodes IEQ
Break Strengths!
7 28 560
1000
2000
3000
4000
5000
6000
7000
8000
9000
733043200
Summary-Admixture Benefits WVRA-Use Free
Water-Close Capillaries Increase Concrete
Durability Sustainability Longevity Avoid needless repairs
Risk Management Tool Eliminate moisture
sensitive flooring failure IEQ Mold & Bacteria
Growth
Regal Cinema-17 Days to Floor Install
Vassar Emergency Medical