The P2P Initiative – Focus on Innovationand Quality

© National Ready Mixed Concrete AssociationAll rights reserved

Announcement

This program is registered with the AIA/CES for continuing professional education. As such, it does not include content that may be deemed or construed to be an approval or endorsement by the AIA of any material of construction or any method or manner of handling, using, distributing, or dealing in any material or product.

Introduction

Continuing education for engineers and architects Length of Presentation: 1 Hours Architects Earn 1 LUs Engineers Earn 1 PDHs NRMCA is an AIA/CES Registered Provider Records kept on file with NRMCA and AIA/CES Records

What is the P2P Initiative?

Prescription-to-Performance An alternative to current prescriptive specifications An initiative of the concrete industry Spearheaded by the NRMCA

P2P GOALS

Allow performance specifications as an alternative to current prescriptive specifications

Leverage expertise of all parties to improve quality and reliability of concrete construction

Assist architects/engineers to address concrete specifications in terms of functional requirements

Allow flexibility on the details of concrete mixtures and construction means and methods

Better establish roles and responsibilities based on expertise Elevate the performance level and quality of ready mixed concrete Foster innovation and advance new technology at a faster pace

What is a prescriptive Specification?

Do not always cover intended performance May conflict with intended performance Limits competitive bidding No incentive for quality control Not in the owner’s best interest

Prescriptive Specification

Typical CriteriaSlump

Max w/cm ratio

Min cement content

Min/max air

Min/Max pozzolans/slag

Blended cements

Aggregate grading

Source Limitations

Chloride Limits

Intended Performance Placing/Finishing Strength Max Shrinkage Resistance To:

• Freeze-Thaw

• Deicer scaling

• Corrosion

• Sulfate attack

• ASR

• Cracking

• Abrasion

Water-cement Ratio

Cement

Water

Air

Cement

Water

Air

Paste

Does w/c alone control strength?

Does w/c alone control permeability?

What is a Performance Specification?

Focus on performance and function Flexibility to adjust mixture ingredients and proportions to

achieve consistent performance Measurable and enforceable

Benefits to the Owner

Improved quality Improved performance Reduced construction time Reduced cost Higher confidence in concrete construction

Benefits to the Engineer/Architect

Focus on function rather than composition Strength, Durability, Shrinkage, etc.

Simplified submittal review Improved product consistency Reduced conflict with contractor/producer Reduced risk – contractor and producer are

responsible for performance

Benefits to the Contractor

Improved communication/coordination

Constructability requirements addressed

Predictable performance Innovate on construction means and

methods

Benefits to the Producer

Eliminates conflicts and improves clarity in specifications

Encourages innovation and rewards investment in quality control

Allows optimization of mixtures for performance

Allows adjustment of materials/proportions to compensate for material or ambient conditions variations

What are the Challenges?

Acceptance of Change Trust / Credibility Knowledge Level (training) Reference Codes and Specifications

Prescriptive limitations

Measurement and Testing Reliability of existing tests Reliability of jobsite tests

What Activities are Underway?

Communication Engineers, Architects, Contractors, and Producers Articles and presentations

Developing Producer Quality System / Qualifications Developing Model Spec / Code Revisions

Look at model codes from other countries (Canada, Europe, Australia) Look at similar initiatives in the US (FHWA and DOTs)

Documenting Case Studies Conducting Research

Test Methods for Performance Quantifying differences between prescriptive and performance mixes

Delivering Training Programs

Lab Study Demonstrating Advantages of Performance Specification

Case 1: Real Floor Specification from a Major Owner Case 2: Typical HPC Bridge Deck Specification Case 3: ACI 318 Chapter 4 Code – prescriptive durability

provisions

Fresh Concrete Tests

Fresh Concrete Properties Slump: ASTM 143 Air Content: ASTM C 231 Density: ASTM C 138 Temperature: ASTM C 1064 Initial Setting Time (Case 1): ASTM C 403 Finishability (Case 1): Subjective rating (5=Excellent to 1=Poor) Segregation (Case 1): Cylinders vibrated, density of top and

bottom half compared

Hardened Concrete Tests

Compressive Strength, ASTM C 39 Length Change, ASTM C 157

Durability Tests

Rapid Chloride Permeability Test (RCPT), ASTM C 1202 Rapid Migration Test (RMT), AASHTO TP 64 Sorptivity, ASTM C 1585 Bulk Diffusion, ASTM C 1556

Case 1 - Concrete Floor Specification

Prescriptive Performance

Specified = 4000 psi;

Average = 5200 psi

Specified = 4000 psi;

Average past records

Max w/c = 0.52, penalties, rejected -

No fly ash or slag SCMs may be used

Slump (max) = 4”, Non AE Slump = 4” – 6”, Non AE

Combined aggregate gradation

8% - 18%-

No HRWR -

- Shrinkage < 0.04% at 28 days

- Setting Time = 5 ± ½ hours

Specified by Contractor

Experimental Program (5 concrete mixtures)

One control (prescriptive) and 4 performance mixturesFS-1: CM = 611, w/cm = 0.49, 8-18% aggregate

FS-2: CM = 517, w/cm = 0.57, 8-18% aggregate

FS-3: CM = 530, 20% FA, w/cm = 0.57, 8-18% aggregate

FS-4: CM = 530, 20% FA with binary aggregates, w/cm = 0.53, #467 stone aggregate

FS-5: CM = 530, 20% SL, 15% FA with binary aggregates, w/cm = 0.54, #467 stone aggregate

Combined Aggregate Grading of FS Mixtures

Combined Aggregate Grading for FS Mixtures Relative to 8-18 criteria

0

5

10

15

20

25

2 1-1/2 1 3/4 1/2 3/8 #4 #8 #16 #30 #50 #100 #200Sieve Size

Ind

ivid

ual

Per

cen

t R

etai

ned

FS-1

FS-2

FS-3

FS-4

FS-5

Compressive Strength and Setting Time

Floor Slab Mixes

4:124:45

5:30 5:175:59

5,870

5,050 4,860 4,9804,720

0:00

2:00

4:00

6:00

8:00

10:00

12:00

FS-1 FS-2 FS-3 FS-4 FS-5

Initi

al S

et ti

me

0

1,000

2,000

3,000

4,000

5,000

6,000

7,000

28 d

ay C

om

pre

ssiv

e S

tren

gth

, psi

Segregation & Shrinkage

Segregation Index: Difference in the coarse aggregate content was consistently about 20% except for Mixture FS-5 which was about 15%

Shrinkage: All mixtures except FS-5 had 28 day shrinkage < 0.020%

Slab Finishability Test

All 5 concrete mixtures had a rating above 4.5 indicating excellent finishability

Durability

3050 3067

538635 584

0

500

1000

1500

2000

2500

3000

3500

FS-1 FS-2 FS-3 FS-4 FS-5

Mixture ID

RC

PT, C

oulo

mbs

Summary – Floor Slab Mixtures

All performance mixtures met performance requirements except Mixture FS-5

Strength over-design factor, limiting w/cm increased cement contents

Use of SCMs was beneficial Continuous aggregate grading mixtures did not impact

performance Performance mixtures had substantial material costs

savings

Case 2 - HPC Bridge Deck Specification

Prescriptive Performance

Specified 28 d strength=4000 psi; Average past records

Specified 28 d strength=4000 psi; Average past records

Max w/cm = 0.39 -

Total CM = 705.

15% FA plus 7% to 8% SFSCM required. Maximum amounts per

ACI 318 for deicer scaling

Air = 4% to 8% Air = 4% to 8%

RCPT < 1500 coulombs RCPT < 1500 coulombs

- Shrinkage < 0.04% at 28 days

Slump = 4” – 6” Slump = 4” – 6”

Specified by Contractor

Experimental Program (4 mixtures)

One control (prescriptive) and 3 performance mixturesBR-1: C = 550, Class F FA = 105, SF = 50; Total = 705

BR-2: C = 426, Class F FA = 150, SF = 24; Total = 600

BR-3: C = 300, SL = 300; Total = 600

BR-4: C = 426, Class F FA = 150, UFFA = 34; Total = 612

w/cm=0.39 for all mixtures except 0.36 for Mix 4

Strength

Compressive Strength: 28 day strengths were much higher than specified (6800 to 8970 psi)

RCPT (ASTM C 1202), RMT (AASHTO TP 64)

0

200

400

600

800

1000

1200

1400

1600

1800

2000

BR-1 BR-2 BR-3 BR-4

RC

PT

, Co

ulo

mb

s

0.000

0.004

0.008

0.012

0.016

0.020

0.024

0.028

RM

T, m

m/(

V-h

r)

RCPT@45D

RCPT@180D

RMT@60D

RMT@180D

Rapid Migration Test

FHWA Performance Grade (AASHTO TP 64) Grade 1: RCPT = 2000 to 3000; RMT = 0.024 to 0.034 Grade 2: RCPT = 800 to 2000; RMT = 0.012 to 0.024 Grade 3: RCPT < 800; RMT < 0.012

Drying Shrinkage (ASTM C 157)

Drying Shrinkage

0.043%

0.024% 0.025% 0.024%

0.000%

0.010%

0.020%

0.030%

0.040%

0.050%

BR-1 BR-2 BR-3 BR-4

Le

ng

th C

ha

ng

e, %

Summary – HPC Bridge Deck Mixtures

All performance mixtures met performance requirements Performance mixtures had similar or better performance

than Prescriptive mixtures Drying shrinkage, workability (stickiness), HRWR dosage,

strength, RCPT, RMT

Performance mixtures had substantial material cost savings

Case 3 - ACI 318 Chapter 4 Prescriptive durability provisions

Objective: Determine if w/cm is the best measure for durability (permeability).

Experimental Program (4 mixtures)

One control (prescriptive) and 3 performance mixtures318-1: 750 lbs Portland cement mixture

318-2: CM = 700; 25% FA (1.16% less paste)

318-3: CM = 564; 25% FA (7.24% less paste)

318-4: Same as #3 but yield adjusted largely by coarse aggregate

w/cm = 0.42 Slump = 3.75” – 6.5”; Air = 4.1% to 7.4%

Results

At same w/cm=0.42

Mix 318-1 318-2 318-3 318-4

Compressive Strength – 28 days, psi

5,440 5,950 5,670 5,600

Length Change – 180 days, %

0.064% 0.048% 0.037% 0.032%

RCPT – 180 days, coulombs

2772 608 533 457

RMT – 180 days, mm/V-hr

0.030 0.0077 0.015 0.0082

Summary – ACI 318 Mixtures

Code limitations on w/cm are no guarantee for high durability concrete

Considerable advances in the use of SCMs and chemical admixtures

Code durability provisions should be performance based

Conclusions

Prescriptive specs do not assure performance Performance mixtures achieved equal or better

performance Great opportunity for mixture optimization Producers compete on their knowledge, resources ACI 318 durability provisions needs to change

ACI 318 Chapter 4 Restructuring

Exposure Category F – Exposure to freezing and thawing cycles

Exposure Category S – Exposure to water-soluble sulfates

Exposure Category P – Conditions that require low permeability concrete

Exposure Category C – Conditions that require additional corrosion protection of reinforcement

Exposure to freezing and thawing cycles

Exposure Category F – Exposure to freezing and thawing cycles

Class Description Condition

F0 Concrete not exposed to freezing and thawing cycles

F1 Moderate Occasional exposure to moisture

F2 Severe Continuous contact with moisture

F3 Very SevereContinuous contact with moisture and exposed to

deicing chemicals

Exposed to water-soluble sulfates

Exposure Category S – Exposure to water-soluble sulfates

Class DescriptionWater-soluble sulfate

(SO4) in Soil,

percent by weight

Sulfate (SO4) in

Water, ppm

S0 Negligible SO4 <0.10 SO4 <150 ppm

S1 Moderate 0.10≤ SO4 <0.20150≤ SO4 <1500 ppm

Seawater

S2 Severe 0.20≤ SO4 <2.00 1500≤ SO4 <10,000 ppm

S3Very

Severe SO4 >2.00 SO4 >10,000 ppm

Conditions that require low permeability concrete

Exposure Category P – Conditions that require low permeability concrete

Class Condition

P0 Low permeability to water not applicable

P1 Concrete intended to have low permeability to water

Conditions that require additional corrosion protection of reinforcement

Exposure Category CConditions that require additional corrosion protection of reinforcement

Class Condition

C0Additional corrosion protection not a concern – for concrete that will

be dry or protected from moisture in service

C1Exposure to moisture but will not be exposed to external source of

chlorides in service

C2Exposure to moisture and an external source of chlorides in service

– from deicing chemicals, salt, brackish water, seawater, or spray from these sources

Requirements for Concrete - Exposure Class F

ExposureClass

Maxw/cm

Min f’c

psiAdditional Minimum Requirements

F0 - - -

F1 0.45 4500 Table 4.4.1 -

F2 0.45 4500 Table 4.4.1 -

F3 0.45 4500 Table 4.4.1 Table 4.4.2

Table 4.4.1—Total Air Content for Concrete Exposed to Cycles of Freezing and Thawing

Nominal maximum aggregate size, in.*

Air content, percent

Class F2 and F3 Class F1

3/8 7.5 6

1/2 7 5.5

3/4 6 5

1 6 4.5

1-1/2 5.5 4.5

2† 5 4

3† 4.5 3.5

Table 4.4.2—Requirements for Concrete Subject to Deicing Exposure Class F3

Cementitious materialsMaximum percent of totalcementitious materials by

weight*

Fly ash or other pozzolans conforming to ASTM C 618

25

Slag conforming to ASTM C 989 50

Silica fume conforming to ASTM C 1240

10

Total of fly ash or other pozzolans, slag, and silica fume

50†

Total of fly ash or other pozzolans and silica fume

35†

Requirements for Concrete - Exposure Class S

ExposureClass

Maxw/cm

Min f’c

psiAdditional Minimum Requirements

S0 - - -

S1 0.50 4000Cement Types II, IP(MS), IS(MS),

P(MS), I(PM)(MS), I(SM)(MS)

S2 0.45 4500Cement Type V

No calcium chloride admixtures

S3 0.45 4500Cement Type V + pozzolan‡

No calcium chloride admixtures

Requirements for Concrete - Exposure Class P

ExposureClass

Maxw/cm

Min f’c

psiAdditional Minimum Requirements

P0 - - -

P1 0.50 4000 -

Requirements for Concrete - Exposure Class C

Exposure Class

Max w/cm

Min f’c psi

Max water-soluble chloride ion (Cl−) content in concrete, percent by weight of cement

Additional Requirement

Reinforced Concrete

C0 - - 1.00 -

C1 - - 0.30 -

C2 0.40 5000 0.15 Min. Cover

Prestressed Concrete

C0 - - 0.06 -

C1 - - 0.06 -

C2 0.40 5000 0.06 Min. Cover

Future Specification for Concrete

Concrete for parking garage slabs and beams shall meet the following requirements:

Specified compressive strength, f’c = 5,000 psi

Exposure class F3, S0, P1, C2

Resources

Visit www.nrmca.org/P2P Download Example Specifications Download P2P Articles Download Research Studies

The P2P Initiative – Focus on Innovationand Quality

Questions?