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: mark.finnell@dot.wi.govWork phone: (608) 449-1337