9.2 Test Order and Parallel Timing

ACI Concrete Field Testing Technician Grade I Study Guide Exam

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1 Orientation: Certification Requirements, Written Exam, Performance Exam, and Study Sources

1.1 Credential Purpose and Official Definition 1.2 Eligibility and the Two-Part Certification Path 1.3 Written Exam Format and Dual Passing Rule 1.4 Performance Exam Format and Grading 1.5 Current Study Sources and CP-1 41st Edition 1.6 Validity, Recertification, and Myth Control

2 JTA, Performance Checklists, Common Fail Points, and Field Mindset

2.1 JTA as the Exam Blueprint 2.2 Written Knowledge Versus Performance Skill 2.3 Performance Checklists and the Six Demonstrations 2.4 Timing, Sequence, and Verbal Description Discipline 2.5 Common Fail Points and Result Recording 2.6 Field Mindset, Exam Habits, and Second Trials

3 ASTM C172: Sampling Fresh Concrete and Field Sample Control

3.1 Representative Sampling Purpose and Exam Role 3.2 Sampling Locations and Middle-Discharge Control 3.3 Composite Sample Timing, Remixing, and Protection 3.4 Sample Size, Large Aggregate, and Wet Sieving 3.5 Sequence With Slump, Temperature, Air, Density, and Specimens 3.6 Performance Exam Verbal Description and Field Habits

4 ASTM C1064 Temperature and ASTM C143 Slump

4.1 ASTM C1064 Purpose, Equipment, and Timing 4.2 Sensor Placement, Stabilization, and Reporting 4.3 Temperature Field Errors and Performance Habits 4.4 ASTM C143 Scope, Equipment, and Setup 4.5 Filling, Rodding, Lifting, and Measuring Slump 4.6 Invalid Slump Results, Reporting, and Integrated Habits

5 ASTM C138: Density, Unit Weight, Yield, and Gravimetric Air

5.1 Purpose, Equipment, and the Calibrated Measure 5.2 Sampling, Filling, and Consolidation Choice 5.3 Strike-Off, Cleaning, Mass, and Density 5.4 Yield, Relative Yield, and Batch Comparison 5.5 Gravimetric Air and Theoretical Density 5.6 Reporting, Validity, and Calculation Traps

6 ASTM C231: Pressure Air Method, Type B Meter, and Aggregate Correction

6.1 Scope, Principle, and When Pressure Air Fits 6.2 Type B Meter Equipment, Calibration, and Setup 6.3 Sampling, Bowl Filling, Consolidation, and Strike-Off 6.4 Type B Sequence: Water, Petcocks, Pressure, and Reading 6.5 Aggregate Correction Factor and Final Air Content 6.6 Reporting, Validity, and Invalid-Result Traps

7 ASTM C173: Volumetric Air Method, Rollameter, Alcohol Correction, and Validity

7.1 Scope, Equipment, and When the Volumetric Method Fits 7.2 Sample, Bowl Filling, Consolidation, and Strike-Off 7.3 Water, Alcohol, Initial Liquid Level, and Sealing 7.4 Inversion, Shaking, Rolling, and Air Release 7.5 Reading Agreement, Out-of-Range Steps, and Invalid Results 7.6 Alcohol Correction, Calculation, Reporting, and Performance Habits

8 ASTM C31: Making and Curing Cylinders and Beams, Initial Curing, and Transport

8.1 Purpose, Sample, Equipment, and Specimen Plan 8.2 Cylinder Molding, Consolidation, Finishing, and Identification 8.3 Beam Molding, Flexural Specimens, and Finishing 8.4 Initial Curing, Protection, Temperature, and Moisture 8.5 Standard Curing, Field Curing, Final Curing, and Interpretation 8.6 Transport, Lab Handoff, Reporting, and Common Failures

9 Integrated Field Workflow: Test Order, Documentation, and Quality Control

9.1 Field Sample to Report Workflow 9.2 Test Order and Parallel Timing 9.3 Documentation and Report Accuracy 9.4 Invalid Results and Retest Decisions 9.5 QA/QC Communication and Acceptance Context 9.6 Contamination, Delays, and Handoff Control

10 Written Exam Strategy: Numerical Values, Calculations, and Category Scoring

10.1 One-Hour Written Exam Pacing 10.2 Category Scoring and the No-Compensation Rule 10.3 High-Yield Numerical Values and Units 10.4 Density, Yield, and Gravimetric Air Calculations 10.5 Air Content Corrections and Validity Checks 10.6 Method-by-Method Practice Plan

11 Performance Exam Strategy: Equipment Setup, Examiner Communication, and Remediation

11.1 Performance Exam Map and Mindset 11.2 Equipment Setup, Station Control, and Safety 11.3 Examiner Communication and Speaking the Work 11.4 One-Step Errors, Timing, and Method Control 11.5 C172 Verbal Description Under Pressure 11.6 Remediation, Retest Planning, and Field Confidence

12 Final Review: Recertification, Career Paths, and Next ACI Credentials

12.1 Two-to-Six Week Final Review Plan 12.2 Final Week and Test-Day Checklist 12.3 CP-1, JTA, and Source Control 12.4 Recertification, Five-Year Cycle, and Re-Exam Requirement 12.5 Career Paths After Field Testing Grade I 12.6 Next ACI Credentials and Growth Map

9.2 Test Order and Parallel Timing

Key Takeaways Explain This Topic AI

The defensible field order is temperature (C1064), slump (C143), air (C231/C173), density (C138), then cylinders (C31), all from one C172 composite.

Slump and air must begin within 5 minutes and cylinders within 15 minutes, so time-critical fresh tests cannot be left until the end.

Density and air can share consolidation work because C138 and the pressure-meter base both require a known-volume, properly rodded container.

Parallel work is allowed only when it does not blur which raw reading, correction, or specimen label belongs to which sample.

Last updated: June 2026

Order the Tests Around Concrete That Is Still Representative

The individual ASTM methods each have their own procedure, but real field work places them into a deliberate order driven by the ASTM C172 time windows . After the composite sample is obtained and remixed , the technician has only 5 minutes to begin slump, temperature, and air, and 15 minutes to begin molding cylinders. Those windows mean the most time-sensitive measurements come first and the technician cannot let slow setup or chatter eat the clock.

The standard, defensible order is:

Temperature — ASTM C1064. Insert the thermometer with at least 3 in. (75 mm) of concrete around the sensor for at least 2 minutes (until the reading stabilizes); read within 5 minutes of sampling.

Slump — ASTM C143. Fill the cone in three equal-volume layers, 25 rods per layer, strike off, lift in 5 ± 2 s, measure to the displaced original center.

Air content — ASTM C231 (pressure) or C173 (volumetric). Use C173 for lightweight or highly porous aggregate because pressure assumptions fail there.

Density and yield — ASTM C138. A known-volume measure is filled, consolidated, struck off, and weighed.

Strength specimens — ASTM C31. Mold cylinders within the 15-minute window.

Where Parallel Work Helps and Where It Hurts

A skilled technician overlaps compatible steps without confusing the data. Temperature can run in parallel with slump setup because the thermometer simply sits in the concrete. The air meter and density measure are often consolidated together — C231's base bowl and C138's measure both need rodding or vibration of a known volume — so the technician can plan one consolidation effort that serves both readings when the same container and procedure apply.

What parallel work must never do is blur sample identity or mix up raw numbers. The dangers are:

Acceptable overlap Risky overlap
Thermometer immersing while slump cone is filled Running two trucks' samples on the same bench unlabeled
Pre-staging air meter while slump is read Recording air before confirming meter calibration
Labeling cylinder molds while density is weighed Letting a helper rod cylinders to an unknown count

If the technician cannot say with certainty which reading came from which sample, the time saved is worthless because the results lose traceability.

Protect the Sample While You Work

Between steps, the remixed sample sits in a clean, damp, non-absorbent pan or wheelbarrow , and the technician shovels it again before drawing each new portion so segregation and bleeding do not bias the next test. A sample left uncovered in sun and wind loses moisture and warms, which can shift slump and air enough to fail an otherwise good batch. The technician should shade the sample and keep tools clean and pre-wetted.

The order is not a rigid script to memorize blindly; it is a logic. Time-critical, change-sensitive tests run first (slump, air). Tests that need controlled consolidation of a known volume (air by pressure, density) are grouped. Cylinders come last but inside the 15-minute window , so the technician budgets time and never lets fresh-property testing run long. Knowing why each test sits where it does lets the technician adapt — for example, doing air by volumetric C173 instead of pressure C231 when the aggregate is lightweight.

Budgeting the Two Clocks Together

The two C172 windows run concurrently from the composite sample, and the technician must budget both at once. The 5-minute window only requires each fresh test to begin in time — once slump is started inside the window, finishing it a minute later is fine. But the 15-minute cylinder window is easy to lose if fresh testing runs long, because molding three layers of multiple cylinders with proper rodding takes real time. A disciplined plan looks like this:

Elapsed from composite Action
0:00 Final portion obtained; remix sample
0:00–1:00 Insert thermometer; begin temperature read
1:00–3:00 Perform slump; record
3:00–6:00 Charge air meter / density measure; consolidate
6:00–9:00 Read air; weigh density measure; record
9:00–15:00 Mold cylinders (begin before 15:00)
Adapt the Order, Keep the Logic

The sequence is a logic, not a rigid script. If lightweight aggregate is used, swap C173 volumetric for C231 pressure because the pressure method's assumption of incompressible aggregate fails on porous particles. If only fresh tests are required (no cylinders that day), the 15-minute window simply does not apply, but the 5-minute window still does. If a helper is available, temperature and slump can overlap so the air and density work starts sooner.

The technician should be able to defend the order with reasoning — time-sensitivity first, shared consolidation grouped, specimens within the window — rather than reciting a memorized list. That reasoning is exactly what lets a technician recover gracefully when a job throws an exception at them.

The sequence also protects data quality in a subtle way: each test that is time-critical and consumes a separate portion (slump, then air) is taken from freshly reshoveled material, so neither test borrows a stiffened or segregated portion from a previous one. Running slump last, after the sample has sat and lost moisture, would bias it low and could fail a perfectly good batch. Ordering by sensitivity therefore is not just about beating the clock — it keeps every reading representative of the concrete as it was discharged.