UFGS 32 13 14 Airfield Concrete Mix Design LESSONS LEARNED By: - - PowerPoint PPT Presentation

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UFGS 32 13 14 Airfield Concrete Mix Design LESSONS LEARNED By: - - PowerPoint PPT Presentation

Jun 14, 2023 108 likes •350 views

UFGS 32 13 14 Airfield Concrete Mix Design LESSONS LEARNED By: Richard L. Allen, PE BOWSER-MORNER, INC. AGGREGATE QUALIFICATION ISSUES It can be difficult to identify aggregates that meet UFGS 32 13 14 in some regions. Aggregate

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UFGS 32 13 14 Airfield Concrete Mix Design LESSONS LEARNED

By: Richard L. Allen, PE BOWSER-MORNER, INC.

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SLIDE 2

AGGREGATE QUALIFICATION ISSUES

  • It can be difficult to identify aggregates that meet

UFGS 32 13 14 in some regions.

  • Aggregate producers are often unfamiliar with the specification.
  • Do not assume that an aggregate meeting State DOT

requirements will meet UFGS 32 13 14 Table 5.

  • The desire for 1 ½” NMA sizes (AASHTO #4) contributes to

problems in sourcing aggregates. Large coarse aggregates tend to have more issues with ASR-deleterious materials than smaller sizes (i.e. #57s, #67s) due to less beneficiation during production.

  • Extra beneficiation ($$) may be necessary to qualify some

materials.

  • Consider allowing well-graded mixes without #4s when

appropriate.

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Sampling ± 2 days ASTM C666A Freeze/Thaw Durability ± 90 days ASR Rapid Mortar Bar ± 35 days ASR Mitigation Trials ± 35 days UFGS 32 13 14 Table 5 Deleterious Exam ± 30 days ASTM C33 Full Quality Analysis ± 30 days

AGGREGATE TESTING TIME LINE

Even when tests are run concurrently it takes a minimum

  • f 92 days to qualify aggregates

per UFGS 32 13 14. ALSO - Per spec, these tests cannot be run sooner than 120 days before production.

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SLIDE 4

TIME REQUIREMENTS: The time requirements for mix review and approval also need to be considered.

  • Sampling (± 18 - 55 gallon drums of material are required)

± 2 days

  • Proportioning by Design Engineer

± 2 days

  • Trial Batching (Small Batches – ASTM C192)

± 7 days

  • Production Batching (large batches – ASTM C192)

± 14 days

  • Strength testing – Compressive & Flexural (ASTM C39 & C78)

± 90 days

  • Final Data Review and Lab Report

± 2 days

MIX DESIGN TESTING TIME LINE

It takes a minimum of ± 115 days to perform trial mixing per UFGS 32 13 14 and prepare a design report

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SLIDE 5

NORMAL TIMELINE

Qualify Aggregate First, then run Mix Designs

Minimum 207 days

Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa

1 2 3 4 5 6 1 2 3 4 1 1 2 3 4 6 7 8 9 10 11 12 13 5 6 7 8 9 10 11 2 3 4 5 6 7 8 7 8 9 10 11 12 13 14 15 16 17 18 19 20 12 13 14 15 16 17 18 9 10 11 12 13 14 15 14 15 16 17 18 19 20 21 22 23 24 25 26 27 19 20 21 22 23 24 25 16 17 18 19 20 21 22 21 27 28 29 30 26 27 28 29 30 31 23 24 25 26 27 28 29 28 30 31

Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa

3 1 7 5 2 4 10 8 14 6 12 3 9 11 17 15 21 13 19 10 16 18 24 22 28 20 26 17 23 25 29 27 24 30

Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa

6 6 3 1 7 13 7 13 4 10 2 8 14 20 14 20 11 17 9 15 21 27 21 27 18 24 16 22 28 28 25 31 23 29 30 31

Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa

5 1 2 3 1 2 3 4 5 6 7 1 2 3 4 6 12 4 5 6 7 8 9 10 8 9 10 11 12 13 14 5 6 7 8 9 10 11 13 19 11 12 13 14 15 16 17 15 16 17 18 19 20 21 12 13 14 15 16 17 18 20 26 18 19 20 21 22 23 24 22 23 24 25 26 27 28 19 20 21 22 23 24 25 27 33 25 26 27 28 29 30 31 29 30 31 26 27 28 29 30

June 2020 July 2020 August 2020 September 2020

AGGREGATE TESTING & MIX DESIGN TESTING AGGREGATE TESTING & MIX DESIGN TESTING AGGREGATE & MIX DESIGNS AGGREGATE TESTING AGGREGATE TESTING AGGREGATE TESTING PRODUCTION PAVING

February 2021 March 2021 April 2021

MIX DESIGN REVIEW & ACCEPTANCE PLANT SET-UP PLANT CERTIFICATION MIX DESIGN TESTING & REPORT

June 2021 July 2021 August 2021 September 2021 May 2021

TRIAL BATCHING & UNIFORMITY TEST STRIP

October 2020 November 2020 December 2020 January 2021

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SLIDE 6

“COMPRESSED” TIME LINE

Begin trial batching as soon as Table 5 Deleterious and ASTM C33 Results are done. (RISKIER)

Minimum 152 days

Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa

1 2 3 4 5 6 1 2 3 4 1 6 7 8 9 10 11 12 13 5 6 7 8 9 10 11 2 3 4 5 6 7 8 7 13 14 15 16 17 18 19 20 12 13 14 15 16 17 18 9 15 14 20 21 22 23 24 25 26 27 19 20 21 22 23 24 25 16 22 21 27 28 29 30 26 27 28 29 30 31 23 29 28 30 31

Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa

3 1 7 5 2 4 10 8 14 6 12 3 9 11 17 15 21 13 19 10 16 18 24 22 28 20 26 17 23 25 29 27 24 30

Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa

6 6 3 1 7 13 7 13 4 10 2 8 14 20 14 20 11 17 9 15 21 27 21 27 18 24 16 22 28 28 25 31 23 29 30 31

Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa Su Mo Tu We Th Fr Sa

5 1 2 3 1 2 3 4 5 6 7 1 2 3 4 6 12 4 5 6 7 8 9 10 8 9 10 11 12 13 14 5 6 7 8 9 10 11 13 19 11 12 13 14 15 16 17 15 16 17 18 19 20 21 12 13 14 15 16 17 18 20 26 18 19 20 21 22 23 24 22 23 24 25 26 27 28 19 20 21 22 23 24 25 27 33 25 26 27 28 29 30 31 29 30 31 26 27 28 29 30

June 2020 July 2020 August 2020 September 2020

AGGREGATE TESTING AGGREGATE TESTING

October 2020 November 2020 December 2020 January 2021

AGGREGATE TESTING AGGREGATE TESTING MIX DESIGN TESTING MIX DESIGN TESTING MIX DESIGN TESTING

February 2021 March 2021 April 2021 May 2021

MIX DESIGN TESTING & REPORT MIX DESIGN REVIEW & ACCEPTANCE PLANT SET-UP TRIAL BATCHING & UNIFORMITY PLANT CERTIFICATION TEST STRIP

June 2021 July 2021 August 2021 September 2021

PRODUCTION PAVING

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AGGREGATE OPTIMIZATION FOR MIX DESIGNS

Recommendations: 1) Obtain aggregate gradation data for previous ± 6 months (CA & FA)

  • Determine average gradations as produced.
  • Determine min/max limits for each sieve size.
  • Compare to samples submitted during lab quality testing.

2) Use the average gradations for aggregate blending calculations and for calculating the Coarseness Factor (CF) and Workability Factors (WF) for the mix. 3) Use the min/max data from recent gradations to check likely range of aggregate variation during the project. This can give you insight into what type of mix variability you can expect during the project.

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SLIDE 8

Min/Max Aggregate Data can be used to predict likely range of variations during project

AGGREGATE OPTIMIZATION FOR MIX DESIGNS

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AGGREGATE OPTIMIZATION FOR MIX DESIGNS

This approach allows you to tailor (to some degree) mix properties to fit planned methods of placement. Need 2 or 3 Coarse Aggregates for Maximum Flexibility

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SLIDE 10

AGGREGATE OPTIMIZATION FOR MIX DESIGNS

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AGGREGATE OPTIMIZATION FOR MIX DESIGNS

“Tarantula” Curve

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SLIDE 12

TRIAL BATCHING REQUIRES A LOT OF LABORATORY EFFORT!

LOW POINT MID POINT HIGH POINT 3 Mixes x 6 break dates x 6 samples per break result in 108 samples and 18 different batches

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OTHER MIX DESIGN ISSUES

re: Supplementary Cementitious Materials for ASR Control Fly Ash

  • Will the design source be available at the time of construction?
  • What is your back-up plan if it is not & what acceptance procedure will be needed?
  • Some clients are duplicating mix designs with other SCM’s just in case.
  • Remember that Fly Ash will suppress early strengths (including 28-day strengths)

Lithium Nitrate

  • Lithium is in high demand for batteries of electronic devices, hybrid cars, etc., etc.

Natural Pozzolans

  • Meta kaolin is being considered for some non UFGS projects.
  • Some regions are seeing cement blended with limestone micro fines
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SLIDE 14

OTHER MIX DESIGN ISSUES

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SLIDE 15

OTHER MIX DESIGN ISSUES (Cont.)

HANGAR SLABS

  • Will these be AE or NAE Mixes?
  • Will a separate mix design be required?
  • What slump limits will be allowed?
  • Will contractor have to work around hydronic heating elements?
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SLIDE 16

PRE-PRODUCTION ISSUES

CONDUCT PRE-PRODUCTION BATCHING TO VERIFY MIX PROPERTIES. Do not assume that mixes will perform the same in regular production as they did in the laboratory setting!

You will need to adjust mixing times, admixture dosages and air adjustments to adapt the trial mix for field purposes.

Do not wait until the day of the test lane placement to figure this out!

When adjusting for air and slump, always put all of the design mix water in, then adjust admixtures. Failure to include all of the design mix water will result in: 1. Surfaces that are stickier and more difficult to finish. 2. Wide fluctuations in test results. 3. Non-predictable strength performance (you’ve changed the mix from what was designed). Only change the water content with the designer’s knowledge and approval.

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SLIDE 17

The loader operator at the batch plant will have a significant impact, for better or for worse, on the success of the project.

CONCRETE PRODUCTION CQC ISSUES

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SLIDE 18

CF and WF ratios are controlled by a very small portion of the aggregate, so getting representative samples is a critical process.

CONCRETE PRODUCTION CQC ISSUES (Cont.)

It is possible for individual aggregate gradations to be within specification limits, but for CF & WF to vary

  • utside of project limits!
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SLIDE 19

CONCRETE PRODUCTION CQC ISSUES (Cont.)

GRADATION CHANGES

If aggregate gradation results cause CF and WF to vary outside project limits, the specification requires you to re-adjust aggregate proportions. RECOMMENDATION

  • Be careful to vet the testing results before making adjustments. If paving is going OK in the

field, don’t make knee-jerk adjustments on the basis of a single outlying gradation result.

  • Resample and re-test the aggregate gradation.
  • If an adjustment is needed, make it based on a rolling average of the last 5-10 test QC

samples.

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SLIDE 20

TESTING ISSUES

  • Proper handling & temporary curing of beam and cylinder

specimens is CRITICAL.

  • Identify lines of communication.
  • Where will the QC lab tests (gradations, strength tests, moistures,

etc.) be performed? Is the technician qualified and experienced at running these tests?

  • Learn how to identify false positives and false negative results.

Unusually high strength test results should be investigated. Production test results should typically not vary more than 15% or so from the mix design results.

  • Discuss approach for evaluating slabs in the event that low breaks

are encountered.

200 400 600 800 1000 1200 2000 4000 6000 8000 10000 Flexural Strength (psi) Compressive Strength (psi) Outliers Outliers

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SLIDE 21
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SLIDE 22

THANK YOU AND GOOD LUCK WITH YOUR PROJECTS!

Richard L. Allen, P.E. rallen@bowser-morner.com