SAM Concrete TestingThe path to better concrete

acceptance testing

PowerPoint Provided by: Tyler Ley, PE, PhD

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Dan DeGraaf, P.E. Michigan Concrete Association

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What is the dream?

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What is the dream?

Concrete that is economical, consistent, and long lasting with

minimal maintenance.

Why are we talking about this?

• The heart of the PEM effort is early age test methods to predict the long term performance of concrete.

• If we don’t try to implement these tests then nothing will change.

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What gets measured gets managed.

- Peter Drucker

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When was the last time that we did this?

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When was the last time that we did this?

• Air meter (Klein and Walker, 1949)

68 years

• Rapid Chloride Permeability Test (Whiting, 1981)

36 years

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Why should I do this?

Does the test measure something I care about?

Do my current tests tell me everything I need to know?

Do I have the resources to make changes?

Does this fit into my priorities?

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Are you sure?

What are your steps to implement?

Convince yourself

Convince others

Try the test

Shadow specification

Specification on a few projects

Daily practice

Set a goal and get started.

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What are your steps to implement?

Convince yourself

Convince others

Try the test

Shadow specification

Specification on a few projects

Daily practice

Set a goal and get started.

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Ask questions

Communicate what you are finding

Find out what works for you

What are your steps to implement?

Convince yourself

Convince others

Try the test

Shadow specification

Specification on a few projects

Daily practice

Set a goal and get started.

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Ask questions

Communicate what you are finding

Find out what works for you

Set a goal and get started.

What are our steps to implement?

Establish that the test meets a need and is useful

Standardize the test

Find critical performance limits

Establish test variability

Recommend a specification

Make changes based on comments

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Super Air Meter (AASHTO TP 118)

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• Volume of air provided is the same for both.

• Case B has a better air void distribution.

A B

What Do You Want in an Air-Void System?

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0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.018

0 2 4 6 8 10 12

AST

M C

45

7 S

pac

ing

Fact

or,

in

Air %

WROS .45

WROS .45 + PC1

ACI 201.2R

You can’t tell the size of the

bubbles by looking at the volume!!!

Small

bubbles

Large

bubbles

Yes!

No!

0.004

0.006

0.008

0.010

0.012

0.014

0.016

0.018

0.020

0.022

0.024

2.0% 3.0% 4.0% 5.0% 6.0% 7.0% 8.0% 9.0%

Sp

acin

g F

acto

r (

in)

Air Content of Concrete (Pressure)

No Polycarboxylate

Polycarboxylate

Open symbols

failed ASTM

C666

Freeman et al., 2012

Mixtures with

large bubbles

Yes!

No!

Ley et al., 2017

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.00 0.10 0.20 0.30 0.40 0.50 0.60

Spac

ing

Fact

or

(in

che

s)

SAM Number

WROS .40WROS + PC1 .40

ACI 201.2R

Recommended

Not Recommended

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

1 2 3 4 5 6 7 8

Du

rab

ility

Fac

tor

Fresh Air %

WROS .40 WROS + PC1 .40

Recommended

Not Recommended

Ley et al., 2017

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0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0.00 0.10 0.20 0.30 0.40 0.50 0.60

Du

rab

ility

Fac

tor

SAM Number

WROS .40WROS + PC1 .40

Recommended

Not Recommended

Ley et al., 2017

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

0.00 0.10 0.20 0.30 0.40 0.50 0.60

Du

rab

ility

Fac

tor

SAM Number

WROS .45

WROS .40

WROS + WR .40

WROS + PC1 .40

WROS + PC1 .35

WROS + PC2 .40

WROS + PC3 .40

WROS + PC4 .40

WROS + PC5 .40

Recommended

Not Recommended

68 mixtures show a 88% agreement.

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Cliff of Doom

Over 227 lab mixtures from two different research groups88% agreement

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Ley et al., 2017

0.008” spacing factor

0

0.002

0.004

0.006

0.008

0.01

0.012

0.014

0.016

0.018

0.02

0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80

Spac

ing

Fact

or

(in

)

SAM Number

AET MnDOT

CODOT

FHWA

GEIGER

IOWA

Kansas

MICHIGAN

MIT

N. DAKOTA

ODOT

PennDOT

UDOT

WisDOT

NO

YES!

13 DOTs over 270 field mixtures81% agreement

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Discussion

The SAM Number correlates to performance in rapid freeze thaw testing.

A SAM Number of 0.20 correlates to a spacing factor of 0.008” for 497concrete mixtures completed by 13 different DOTs and two research groups.

88% agreement in lab

81% agreement in the field

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0

10

20

30

40

50

Pre

ssu

re (

psi)

Time

Top Chamber, Pc

Bottom Chamber, Pa

Equilibrium Pressure

SAM

number

Air content and SAM number given here

Atmospheric

Pressure

35 psi other pressures

not shown

Returned to

Atmospheric

Pressure

High spacing

factorLow spacing

factor

How is this useful???

• If you have a high spacing factor (bubbles far apart) then pressure step 1 will cause the bubbles to dissolve

• When we apply pressure step 2 there will be a large difference in how the concrete responds to pressure.

• This will cause a high SAM number.

How is this useful???

• If you have a low spacing factor (bubbles close together) then pressure step 1 will not dissolve many bubbles

• When we apply pressure step 2 there will be a small difference between the two pressure curves.

• This will cause a low SAM number.

Discussion

The SAM Number tells you about the bubble size distribution in fresh concrete and the total air does not do this.

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Test Method Parameter COV

Time to

complete the

test

SAM SAM Number1 15.2% 10 min

ASTM C457 Spacing Factor2

20.1% 7 days

ASTM C666 Durability Factor3

22.7% 3.5 months

1Assumes a SAM Number of 0.32 and a standard deviation of 0.049 from this paper

2From ASTM C457

3From ASTM C666 with a durability factor of 75 and Method B170 SAM comparisons were used to determine this.

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How variable is the test?

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One standard deviation

Two standard deviations

high low high low

Compressive strength (psi) 5000 5500 4500 6000 4000

Air meter (%) 6 6.4 5.6 6.8 5.2

SAM 0.20 0.23 0.17 0.26 0.14

Spacing factor (in) 0.008 0.010 0.006 0.0112 0.0048

Freeze Thaw (DF) 70 86 54 102 38

average value

68% of the data will

be in this range

96% of the data will

be in this range

70

75

80

85

90

95

0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5

Per

cen

tage

agr

eem

ent

SAM Number

Durability Factor 70

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60

65

70

75

80

85

90

0.1 0.15 0.2 0.25 0.3 0.35

Pe

rcen

t ag

reem

en

t

SAM Number

spacing factor = 0.008"

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Ley et al., 2017

Daily Meter Check

• Pressure chamber to 45 PSI and hold it.

• Wait 2 minutes

• Pressure drop should be less than .04 PSI

• If greater – look for leaks

• Biggest issue is cleaning the rim

• 2nd issue is getting all the air bubbles out of the base

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Does anyone enjoy using the syringe in an air test?

What if we used a funnel instead?

Shotgun

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Shotgun

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Shotgun

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Recommended SAM Specification

SAM Number Action

< 0.25 Accept the concrete

0.25 - 0.30

Increase air content

on next truck, accept

the concrete

> 0.30 Reject the concrete

Air content > 4%

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FieldMixture Design

SAM Number < 0.20Air content > 4%

Discussion

If the producer designs the SAM Number to be at 0.20 at their working air content then they will have < 2% chance of getting a failing test in the field.

By allowing actions at different SAM Numbers then the producer can bring their materials back within specification before getting them rejected.

The rejection limit is determined by freeze thaw testing (ASTM C 666).

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All our dreams can come true if we have the courage to pursue them.Walt Disney

Set a goal and get started.

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“Super Air Meter”in Michigan

Introduction of SAM to MDOT,Multi-State Pooled-Fund Projects• 2014: MDOT along with 17 other state DOTs: “Improving Specifications to Resist Frost Damage in

Modern Concrete Mixtures”, TPF-5(297). Completion date: 2019• Lead state – Oklahoma DOT• This pooled fund initiative is focused on the development of the SAM• Acquired 2 SAMs for multi-state data gathering and system refinement

• 2017: MDOT along with 12 other states and the FHWA: “Performance Engineered Concrete Paving Mixtures”, TPF-5(368). Completion date: 2021

• Lead state – Iowa DOT• The National Concrete Consortium (NCC) will be the anchor organization for dissemination of research and

outreach for this project (32 dots, industry, academia)• This pooled fund initiative is to develop guidance for the next-generation of performance-based concrete

paving specifications…implement what we know, monitor, measure, and spec refinement• Included in this project will be further study of the SAM and its associated AASHTO provisional test method

• These pooled-fund efforts will greatly aide toward developing Michigan-based specifications for incorporation of the SAM into the MDOT concrete acceptance program

Super Air Meter in Michigan

• FHWA Sponsored State Transportation Innovation Council (STIC)

• STIC Application• September 2016

• SAM Acquisition

• Training, Spec Development, Outreach

STIC Activities, to date

• Spring 2017• Purchased 8 SAMs – total 10

• Summer 2017• Brought Dr. Ley in for a Joint MDOT/MCA training/certification course

• MCA hosted day-long event (classroom and practical laboratory setting) - 30 attendees• MDOT technicians – 12• MDOT Supervisors – 3• Wayne County Road Commission – 1• Contractors – 2• Concrete Suppliers – 1• Consultants – 6• MCA Staff – 5

• MDOT provided 10 SAMs

• Six MDOT SAMs sent to Regions for informational gathering and outreach

MDOT Roads Innovation Task Force (RITF)

• SAM will be demonstrated on two concrete paving projects:• 30-year design life (50-year service life): July 2017 project letting. Bay Region, I-69

from I-75 to I-475

• 50-year design life (75-year service life): Spring 2018 project letting. Grand Region, US-131 from 10 Mile Road to 14 mile Road

• QC and QA informational shadow testing via “Special Provision for Durability Based Field Testing”

• SAM

• Surface Resistivity

AASHTO Committee on Materials and PavementsCOMP (formerly Subcommittee on Materials)

• TPF-5(297):“Improving Specifications to Resist Frost Damage in Modern Concrete Mixtures”

• Presented to Technical Section 3b, Fresh Concrete Properties in 2016• Adopted the SAM as a Provisional Standard Test Method (TP-118)

• TPF-5(368): “Performance Engineered Concrete Paving Mixtures”• Presented to Technical Section 3b, Fresh Concrete Properties in 2016• Adopted the PEM as a Provisional Standard Practice (PP-84)

MDOT Moving Forward

• Nationally - Field acceptance using SAM for payment is not quite there…yet

• Currently own 10 SAMs• 2 - pooled-fund project• 8 – STIC grant

• Partner with MCA to incorporate SAM training module into current MCA Level 1 certified concrete technician course – 2018

• Continue active participation in pooled-fund projects:• “Improving Specifications to Resist Frost Damage in Modern Concrete Mixtures”,

TPF-5(297),• “Performance Engineered Concrete Paving Mixtures”, TPF-5(368)

• Pooled-fund activities along with Michigan-based field testing and outreach will steer future MDOT implementation

2017 SAM Field Testing Data

Questions?

General video about measuring air in concrete: https://www.youtube.com/watch?v=gOAft3z9Sa4&list=PLRq6Z9d0kCT_ObxZG5Mh2edgOyirtn0Co&index=6

videos about the theory behind the SAM and how to run it:

http://www.superairmeter.com/videos.html

https://youtu.be/wKtOKg8eQSw