concrete: what’s new, what’s changed and what’s coming
TRANSCRIPT
Concrete: What’s New, What’s Changed and What’s Coming
Materials TrainingConcrete Engineer-Consultant
Spring, 2021
Mark Finnell
Topics for Today
• The SAM: Common Mistakes and the Future• Optimized Aggregate Gradations (OAG)• The Rise of Portland Limestone Cements (PLCs)• Miscellaneous ItemsMIT Dowel Scanner Surface Resistivity
The SAM: Common Mistakes and the Future
Common Mistakes• Poor filling procedure Poor use of squeeze bottles Not tipping meter
• Accidental lever press• Using an internal vibrator to
consolidate sample
• Not recording equilibrium pressures
• Not letting SAM acclimate to surrounding air temperature
Future of the SAM
• This construction season: Business as usualQC will be testing at a frequency of once per lot (715.3.1.1 Para. 2)QV will continue testing at a frequency of every 5th lot (715.3.1.3 Para. 1)
• It is strongly encouraged to practice the SAM prior to operating it
Future of the SAM
• The future:WisDOT’s goal is to implement SAM by 2023 Specifications
• Finalize limits for SAM Number• Frequency of testing for QC and QV• Develop dispute resolution process
Assess future technologies for the SAM• The MinT• CAPE 2.0
Optimized Aggregate Gradations: What to Know and What to Look For
Optimized Aggregate Gradations (OAG): What is It?
• The idea of maximizing the volume of aggregates in a mixture• The goal of OAG is to reduce cementitious content Increases strength, durability and sustainability Reduces cost
OAG: The Tarantula Curve
• Developed by Dr. Tyler Ley at Oklahoma State University
• Based on blended aggregate gradations Volumetric Percent Retained
0
5
10
15
20
25
2"
1 1/
2" 1"
3/4"
1/2"
3/8" # 4
# 8
# 16
# 30
# 50
# 10
0
# 20
0Perc
ent
Ret
aine
d, %
Vol
Sieve
Tarantula
OAG and WisDOT
• OAG is covered under STP-715-005 Covers pavement only Allows cementitious contents of 520 lbs./cy Typically used on High Performance Concrete (HPC) corridors Contractor’s may volunteer to use it
• The STP includes incentive
OAG and WisDOT: Common Questions
• How do I apply a failing QV Gradation Test to OAG? Add the QV data point to the QC running average Think of it as an extra QC test
• Moves the running average 1 extra step• When do I apply the incentive? The incentive is applied to lots that are within the Tarantula Curve Limits
• The Job Mix Formula (JMF) is independent of the incentive
OAG and WisDOT: Common Questions
• What role does the Job Mix Formula (JMF) play? The JMF is a tool used to control the contractor’s operations. It determines if
operations can continue. The JMF does not dictate incentive.
OAG and The Future
• OAG is coming to the 2022 Specification Key Differences:
• No more incentive• New minimum cementitious content: 500 lbs./cy• No more JMF
More on this will be discussed in the future
The Rise of Portland Limestone Cement (PLC)
What is Portland Limestone Cement (PLC)?
• A blended cement containing finely ground limestone ASTM Designation: Type IL (C595)
• Limestone is a mineral filler• Typical nominal replacements: As low as 5% No more than 15%
What Benefit Does PLC Have?
• The limestone acts as a catalyst Aids in cement hydration
• Reduces carbon footprint of concrete
• Does not affect other propertiesOnly true at replacement levels
lower than 15%Courtesy of: Berodier, E. S. K. S. G., & Scrivener, K. (2014). Understanding the Filler Effect on the Nucleation and Growth of C‐S‐H. Journal of the American Ceramic Society, 97(12), 3764‐3773.
PLCs and WisDOT
• WisDOT recognizes PLCs under 501.2.1 Uses ASTM C595 as guidance Key difference:
• Only allow up to 10% replacement• No individual test should exceed 12% replacement
• PLC will become more common Cement and Concrete industry becoming more carbon neutral
How to Handle PLCs
• No different than handling ordinary cement Cement acceptance based on C595
• Limestone in cement is not a supplementary cementitious material (SCM) It is not a fly-ash, slag or silica fume Does not contribute to replacement of SCMs
How to Handle PLCs
• PLCs containing greater than 10% replacement in 2021 ASTM C595 allows 15% replacement The 2022 Specification will mirror C595 Reach out to BTS for assistance
• Mark Finnell• Jim Parry
Miscellaneous Items
The MIT Dowel Scanner
• Uses the same technology as the T2
• The device can scan dowel bar alignment and depth DBIs Dowel Bar Baskets
The MIT Dowel Scanner
• Currently gathering data with the scanner• Used in forensic investigation• Need to assess the accuracy of scanner for Dowel Bar Baskets A new software upgrade removes interference
• The goal: use as a preventative tool Scan joints to identify potential issues
• It would be helpful for the regions to identify projects Contact Mark Finnell or Jim Parry
Surface Resistivity
• WisDOT is moving forward with surface resistivity (AASHTO T358)
• This measures the permeability of concreteWill replace RCPT test
• Fast and easy test
Surface Resistivity
• When to expect surface resistivity: Shadow spec in the 2022 Specification
• What will be expected:QC will be testing once per lotQV will be testing every 5th lot Concrete Strength Testers will be responsible for measurements CMM guidance and updates to HTCP will be provided
Questions?
• Contact Information:Mark Finnell Email: [email protected] phone: (608) 449-1337