Concrete Performance Evaluation on MTO Projects Webinar

Oct. 23rd, 2018

Facilitators

Bart Kanters, P.Eng.PresidentConcrete Ontario

Alen Keri, P.Eng.Technical Services EngineerConcrete Ontario

Housekeeping

45 minute webinar with 15 minutes Q & A All participants are muted Questions? Use ‘Questions’ Pane Webinar will be recorded and posted on the Concrete Ontario

YouTube channel. www.ConcreteOntario.org PDF version of the presentation and the link to the YouTube video will

be emailed to all participants

PresenterHannah SchellHead, Concrete SectionMTO Materials Engineering and Research Office The Concrete Section is responsible for development of technical policy and

standards for concrete and related products for Ontario’s Provincial highway structures and pavements.

Hannah is a graduate of Queen’s University at Kingston and a licensed Professional Engineer in the Province of Ontario.

She is the past Chair of Canadian Standards Association (CSA) Technical Committee A283 which is responsible for the qualification code for concrete testing laboratories, and is a member of the CSA A23.1/23.2 standard committee, on concrete materials and methods of construction, and test methods.

She is also a member of American Concrete Institute (ACI) Committee 201, Durability of Concrete.

Concrete Performance Evaluation on Ministry of Transportation (MTO)

Contracts

Hannah SchellHead, Concrete Section

MTO Materials Engineering and Research Office

5

September 26, 2018

Overview

• Results from Quality Assurance testing on MTO Contracts

during 2017

• Trends in referee testing on MTO contracts

• Specification changes and updates for 2018

• Current issues in concrete construction

6

MTO Quality Assurance — Acceptance of Concrete

• Compressive strength: as specified in the contract (30MPa, 35MPa)

• Air void system (AVS) of hardened concrete:• Air content: minimum 3.0%

• Spacing factor:• Cast-in-place concrete: maximum 0.23 mm

• Precast concrete: maximum 0.20 mm

• Rapid chloride permeability (RCP)• Maximum 2500 Coulombs when tested at 28-32 days.

7

Compressive Strength — 30 MPa and 35 MPa2017 Results – OPSS 1350 Acceptance Method A

Notes:-Data incomplete (does not include all MTO contracts)- Includes forecasts for ongoing contracts- No penalties were reported for these contracts

0

10

20

30

40

50

60

70

30MPa 35MPa

No

of M

TO C

ontr

acts

Compressive Strength

No BonusWith Bonus $1-$5/m3

8

Compressive Strength — 30 MPa2017 Results – OPSS 1350 Acceptance Method A

9

Notes:- Data incomplete (does not include all MTO contracts)- Includes forecasts for ongoing contracts- No penalties were reported for these contracts

0

5

10

15

20

25

30

35

Central East West

No

of M

TO C

ontr

acts

MTO Region

No Bonus

With Bonus $1-$5/m3

Air Void System (AVS) — Air Content2017 Results - Cast-in-place Concrete

10

0.0

2.5

5.0

7.5

10.0

12.5

15.0

17.5

20.0

22.5

0.0-

2.9

3.0-

3.9

4.0-

4.9

5.0-

5.9

6.0-

6.9

7.0-

7.9

8.0-

8.9

9.0-

9.9

10.-1

0.9

11.0

-11.

9

12.0

-12.

9

13.0

-13.

9

>14.

0

Perc

enta

ge o

f Occ

urre

nce

(%)

Hardened Air Content (%)

Total no. of AVS tests = 14452.4% 97.6%

3.0%

Air Void System (AVS) — Spacing Factor2017 Results - Cast-in-place Concrete

11

0.0

2.5

5.0

7.5

10.0

12.5

15.0

Perc

enta

ge o

f Occ

urre

nce

(%)

Spacing Factor (mm)

Total no. of AVS tests = 1445

0.23mm

2.1%97.9%

Air Void System (AVS) — Air Content and Spacing Factor2017 Results - Cast-in-place Concrete

12

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0

Spac

ing

Fact

or (m

m)

Hardened Air Content (%)

0.23mm

Total no. of AVS tests = 1435

Air Void System (AVS) — Air Content and Spacing Factor2017 Results - Cast-in-place Concrete

13

0.000

0.050

0.100

0.150

0.200

0.250

0.300

0.350

0.400

0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0

Spac

ing

Fact

or (m

m)

Hardened Air Content (%)

0.23mm

Total no. of AVS tests = 1435

BonusBonus $5/m3

Air Void System (AVS) — Specific Surface2017 Results - Cast-in-place Concrete

14

0.0

2.5

5.0

7.5

10.0

12.5

15.0

17.5

Perc

enta

ge o

f Occ

urre

nce

(%

)

Specific Surface (mm-1)

Total no. of AVS tests = 130925 mm-1

18.1% 81.9%

Air Void System (AVS) — Spacing Factor Evolution

15

0.0

2.5

5.0

7.5

10.0

12.5

15.0

17.5

20.0

Perc

enta

ge o

f Occ

urre

nce

(%)

Spacing Factor (mm)

Year End Results - 2017 (1445 AVS tests) Year End Results - 2014 (853 AVS tests)Year End Results - 2006 (1005 AVS tests)

0.23mm

Air Void System (AVS) – Spacing Factor2006, 2014 and 2017 Results - Cast-in-place Concrete

16

0.0

2.5

5.0

7.5

10.0

12.5

15.0

17.5

20.0

Perc

enta

ge o

f Occ

urre

nce

(%)

Spacing Factor (mm)

Year End Results - 2017 (1445 AVS tests) Year End Results - 2014 (853 AVS tests)Year End Results - 2006 (1005 AVS tests)

0.23mm

2006 Avg. = 0.165mm2017 Avg. = 0.125mm

2014 Avg. = 0.145mm

Rapid Chloride Permeability (RCP) — Lowest to Highest2017 Results - Cast-in-place Concrete

17

Note: Each RCP test is the average of two slices

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

0 30 60 90 120 150 180 210

RC

P T

est V

alue

s (C

oulo

mbs

)

RCP Test Number

Total no. of RCP tests = 204

Rapid Chloride Permeability (RCP)2017 Results - Cast-in-place Concrete

18Note: Each RCP test is the average of two slices

172

24

30

20

40

60

80

100

120

140

160

180

200

No

of R

CP

Test

s

Central, West, and East Regions

Less than or equal to 2500 CoulombsMore than 2500 Coulombs and less than or equal 3500 CoulombMore than 3500 Coulombs

Rapid Chloride Permeability (RCP) — Results by Supplier (multiple plants)2017 Results - Cast-in-place Concrete

19

Note: Each RCP test is the average of two slices

0

10

20

30

40

50

60

70

80

90

A b c d e f (single plant)

No.

of R

CP

Test

s

Concrete Supplier

Less than or equal to 2500 CoulombsMore than 2500 Coulombs

Air Void System (AVS) — Air Content2017 Results - Cast-in-place Concrete and Precast Concrete

20

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

Perc

enta

ge o

f Occ

urre

nce

(%)

Hardened Air Content (%)

Cast-in-place Concrete (No. of samples 1445)Precast Concrete (No. of Samples 36)

Air Void System (AVS) — Air Content2017 Results - Cast-in-place Concrete and Precast Concrete

21

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

Perc

enta

ge o

f Occ

urre

nce

(%)

Hardened Air Content (%)

Cast-in-place Concrete (No. of samples 1445)Precast Concrete (No. of Samples 36)

3.0%

Air Void System (AVS) — Spacing Factor2017 Results - Cast-in-place Concrete and Precast Concrete

0.0

2.5

5.0

7.5

10.0

12.5

15.0

17.5

20.0

22.50.

0-0.

059

0.06

-0.0

690.

07-0

.079

0.08

-0.0

890.

09-0

.099

0.1-

0.10

90.

11-0

.119

0.12

-0.1

290.

13-0

.139

0.14

-0.1

490.

15-0

.159

0.16

-0.1

690.

17-0

.179

0.18

-0.1

890.

19-0

.199

0.2-

0.20

90.

21-0

.219

0.22

-0.2

290.

23-0

.239

0.24

-0.2

490.

25-0

.259

0.26

-0.2

690.

27-0

.279

0.28

-0.2

890.

29-0

.299

0.3-

0.30

9>0

.31

Perc

enta

ge o

f Occ

urre

nce

(%)

Spacing Factor (mm)

Cast-in-place Concrete (No. of samples 1445)Precast Concrete (No of samples 36)

22

Air Void System (AVS) — Specific Surface2017 Results - Cast-in-place Concrete and Precast Concrete

23

0.0

2.5

5.0

7.5

10.0

12.5

15.0

17.5

20.0

22.5

25.0

27.5

30.0

Perc

enta

ge o

f Occ

urre

nce

(%

)

Specific Surface (mm-1)

Cast-in-place Concrete (No. of samples 1306)Precast Concrete (No. of samples 36)

Rapid Chloride Permeability (RCP)2017 Results - Cast-in-place Concrete and Precast Concrete

24

Note: Each RCP test is the average of two slices

0

500

1000

1500

2000

2500

3000

3500

4000

4500

0 30 60 90 120 150 180 210

RC

P Va

lue

(Cou

lom

bs)

No. of RCP Tests

Cast-in-place Concrete (No. of RCP Test = 204)

Precast Concrete (No of RCP tests = 151)

Referee Testing on 2017 Contracts — Summary

• Air Void System (AVS) in Hardened Concrete - 66 (55 QA failures) total

• 31 confirmed QA result, 24 overturned

• Compressive Strength – 15 total• 11 confirmed QA result, 4 overturned

• Rapid Chloride Permeability (RCP) – 9 total• 1 confirmed QA result, 8 overturned

• Admixture Properties – 15 total• 6 confirmed QA result, 9 overturned

25

2017 Referee Requests — Summary

Type of Test

Region – Lots [Sublots or samples]

All-In CR WR ER NER NWRTotal 78 12 31 7 10 18

AVS 44 [66] 3 [4] 24 [42] 4 [4] 5 [8] 8 [8]

Strength 14 [15] 2 [2] 3 [3] 1 [1] 3 [4] 5 [5]

Admixture 11 [15] 0 [0] 3 [3] 1 [1] 2 [2] 5 [9]

RCP 9 [9] 7 [7] 1 [1] 1 [1] 0 [0] 0 [0]

26

Number of Referee Requests Each Year

Type of referee test invoked

Year

2013 2014 2015 2016 2017

Compressive Strength 1 28 20 17 14

Air Void System (AVS) 32 15 24 39 44

Rapid Chloride Permeability (RCP) 4 7 14 5 9

Admixtures 4 3 4 12 11

27

Compressive Strength

• 15 QA tests failed to meet the specified strength (ranging

from 30 to 60 MPa). Except for one, specimens were

cylinders.

• Out of the 15 referee tests, only 4 did not confirm the QA

result (i.e., at least 10% difference between QA & REF per

OPSS 1350); eleven test results were not compliant.

28

Compressive Strength

29

Air Void Analysis (AVS)

• Out of 59 QA failures, 28 were related to deficient air

content (i.e. below the specified 3.0%) and 31 due to high

spacing factor (i.e. above that specified for the application).

• The referee results confirmed 7 out of the 28 QA failures

due to deficient air content, and 30 out of 31 QA failures

due to high spacing factor.

30

Air Void Analysis (AVS)

31

Air Void Analysis (AVS)

32

Rapid Chloride Permeability (RCP)

• 9 QA tests failed to meet the specified requirement of 2500

coulombs, for concrete mixes with a specified compressive

strength of 30 MPa.

• The referee results confirmed 1 out of the 9 QA failures (i.e.

QA results were overturned in 8 cases).

33

Rapid Chloride Permeability (RCP)

34

35

Specifications and Standards

• Modifications related to elimination of Quality VerificationEngineer (QVE) requirements

• Contractor must submit “Request to proceed”; receive “Permissionto proceed” before going on to next operation

• Inspection by MTO will replace QVE inspection in some cases e.g.reinforcing steel placement for structures

• Manufacturer’s Engineer sign-off required for manufacturedproducts e.g. precast concrete components

• Updated OPSS PROV 1002 and SP110S17 for concreteaggregates

• Expanded use of permeability (RCP) requirement instructural concrete

• Developing new Special Provision for precast structuralculverts (>3m span)

36

Current Issues

• Temperature concerns

• Impacts of aggregate gradation

• Significant quality deficiencies related to workmanship

37

Detection of internal voids using ground-penetrating radar (GPR) technology

Surface and Internal Voids

Void (90mm long and 40mm wide) extends from 50mm to 90mm below the surface

Exposed void

Void (85mm long and 35mm wide) extends from 40mm to 70mm below the surface

Cold Joints

Cold Joints

Lack/Loss of Concrete Workability

44

OPSS PROV 904 “No material shall be applied to the concrete surface or the finishing tools to aid in the finishing.”