What A Contractor Needs to Know About the New AASHTO Provisional Guidelines and Suite of Tests

34 Pages·2016·5.26 MB·English

by  Graphic Designer

Performance Engineered
Mixtures Program
What A Contractor Needs to Know
About the New AASHTO Provisional
Guidelines and Suite of Tests
Dr. Peter Taylor, PE (IL)
1
What is it?
• A program to

Understand what makes concrete
“good”

Specify the critical properties and test
for them

Prepare the mixtures to meet those
specifications
2
Step 1
• A better specification

Require the things that matter
Transport properties (everywhere)
Aggregate stability (everywhere)
Strength (everywhere)
Cold weather resistance (cold locations)
Shrinkage (dry locations)
Workability (everywhere)
3
Transport
Properties/Permeability (6.6)
Mixture Selection
Section Property Specified Test Specifed Value Acceptance Special Notes
Qualification Details
6.6 Transport Properties
Water to Cement
6.6.1.1 0.45 ~ Yes Yes
Ratio AASHTO T 318
Other criteria
6.6.1.2 RCPT Value AASHTO T 277 2000 ~ Yes Yes
could be selected
* Note this is
currently based
Choose
on saturated
Only One
Formation AASHTO xx or curing and an
6.6.1.3 500 ~ Yes through ρ
Factor/Resistivity AASHTO yy adjustment is
needed to match
with AASHTO
Spec
Ionic Penetration, F AASHTO xx or 25 mm at
6.6.2.1 Yes, F through ρ
Factor AASHTO yy 30 year
Aggregate Stability (6.7)
Specifed Mixture Selection Special
Section Property Specified Test Acceptance
Value Qualification Details Notes
6.7 Aggregate Stability
AASHTO T 161, ASTM
6.7.1 D Cracking ~ ~ Yes No
C 1646/666
Alkali Aggregate
6.7.2 AASHTO PP 65 ~ ~ Yes No
Reactivity
Concrete Strength (6.3)
Mixture Selection Special
Section Property Specified Test Specifed Value Acceptance
Qualification Details Notes
6.3 Concrete Strength
4.1 600
6.3.1 Flexural Strength AASHTO T 97 Yes Yes
MPa psi
Choose
either
or both
Compressive 24 3500
6.3.2 AASHTO T 22 Yes Yes
Strength MPa psi
Hardened Cement Paste
Freeze-Thaw Durability (6.5)
Mixture
Section Property Specified Test Specified Value Acceptance Selection Details Special Notes
Qualification
6.5 Durability of Hydrated Cement Paste for Freeze-Thaw Durability
Choose
Either
6.5.1.1 Water to Cement Ratio AASHTO T 318 0.45 ~ Yes Yes 6.5.1.1
or
6.5.2.1
6.5.1.2 Fresh Air Content AASHTO T 152, T196, TP 118 5 to 8 % Yes Yes
Choose
≥ 4% Air; %,
6.5.1.3 Fresh Air Content/SAM AASHTO T 152, T196, TP 118 Yes Yes only one
SAM ≤ 0.2 psi
Variation controlled
with mixture
proportion
6.5.2.1 Time of Critical Saturation "Bucket Test" Specification 30 Years Yes No Note 1 Note 2
observation or F
Factor and Porosity
Measures
Are calcium or
6.5.3.1 Deicing Salt Damage ~ 35% SCM Yes Yes magnesium chloride
used
Are calcium or
magnesium chloride
6.5.3.2 Deicing Salt Damage ~ ~ ~ Yes Yes Choose one
used, needs a use of
specified sealers
Are calcium or
6.5.4.1 Calcium Oxychloride Limit Test sent to AASHTO < 0.15g CaOXY/g paste Yes No magnesium chloride
used
Note 1: Choose Either 6.5.1.1 or 6.5.2.1
Note 2: Choose either 6.5.1.2, 6.5.1.3, or 6.5.2.1
Reducing Unwanted Cracking
Due to Shrinkage (6.4)
Mixture Selection
Section Property Specified Test Specifed Value Acceptance Special Notes
Qualification Details
6.4 Reducing Unwanted Cracking Due to Shrinkage
6.4.1.1 Volume of Paste 25% Yes No
Unrestrained Volume at 28
6.4.1.2 ASTM C157 420 µε Yes No
Change day
Unrestrained Volume 360, 420, at 91
6.4.2.1 ASTM C157 Yes No
Change 480 µε days
AASHTO T at 180 Choose
6.4.2.2 Restrained Shrinkage crack free Yes No
334 days only
one
AASHTO T
6.4.2.3 Restrained Shrinkage σ< 60% f'r at 7 days Yes No
???
as
6.4.2.4 Probability of Cracking ~ 5, 20, 50% Yes No
specified
Workability (6.8)
Mixture Selection Special
Section Property Specified Test Specifed Value Acceptance
Qualification Details Notes
6.8 Workability
<6.25 mm, < 30%
6.8.1 Box Test ~ Yes No
Surf. Void
Modified V-Kelly 15-30 mm per root
6.8.2 ~ Yes No
Test seconds
Step 2
• Better test methods (for those critical
properties)

VKelly

Box

Resistivity / Formation
factor

Sorptivity

Dual ring

SAM
10