Study guide
4.1 ASTM C1064 Purpose, Equipment, and 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
4.1 ASTM C1064 Purpose, Equipment, and Timing
Key Takeaways Explain This Topic AI
ASTM C1064/C1064M measures the temperature of freshly mixed hydraulic-cement concrete and applies to mixtures with nominal maximum aggregate up to 3 in.
The temperature device must read to at least 1 degree F (0.5 degree C) and be accurate to plus or minus 1 degree F (0.5 degree C) across 30 to 120 degrees F (0 to 50 degrees C).
When measured from a C172 sample, the temperature must be completed within 5 minutes after obtaining the sample.
The device must be calibrated or verified at least once per year and whenever there is reason to question its accuracy.
The result is reported to the nearest 1 degree F or 0.5 degree C.
Last updated: June 2026
Temperature as a Fresh-Concrete Property
ASTM C1064/C1064M covers measuring the temperature of freshly mixed hydraulic-cement concrete. Temperature drives slump loss, setting time, air-void stability, finishing behavior, and curing risk, so most specifications set hot-weather and cold-weather limits that this test verifies. ACI 301 and many projects cap fresh-concrete temperature near 95 degrees F in hot weather; cold-weather placement limits commonly require a minimum near 50 to 55 degrees F depending on section size.
A temperature result is also a snapshot in time: wait too long, read a shallow sample, or read before the device stabilizes, and the value describes the environment more than the concrete.
The scope is itself an exam point. C1064 applies to concrete with a nominal maximum aggregate size up to 3 in. (75 mm) . Larger-aggregate mixtures fall outside the method because the device cannot get the required surrounding cover. This is why the standard pairs an aggregate rule with a cover rule, discussed in the next section.
Why does the field technician care so much about a single number? Because temperature is an early-warning property. A load arriving above the hot-weather limit signals likely rapid slump loss, flash set risk, plastic-shrinkage cracking, and reduced long-term strength. A load below the cold-weather minimum signals slow setting, delayed finishing, and freezing risk before the concrete gains protective strength. The technician who records temperature accurately gives the producer and contractor the data needed to accept, reject, or adjust placement methods such as ice, chilled water, retarders, heated aggregate, or insulation.
Equipment Accuracy and Verification
Equipment requirements are heavily tested. The temperature-measuring device must be readable to 1 degree F (0.5 degree C) and accurate to plus or minus 1 degree F (plus or minus 0.5 degree C) throughout the range of 30 to 120 degrees F (0 to 50 degrees C) . Candidates must separate readability (the smallest increment shown) from accuracy (how close the reading is to truth) — a digital display showing tenths is not automatically accurate to a tenth.
The device must be calibrated or verified at least once per year and whenever there is reason to question its accuracy, such as after a drop, a suspicious reading, or visible damage. Verification is commonly done against a reference thermometer with a documented relationship to NIST standards.
- C1064 requirement Exact value Exam trap
- Readability 1 degree F (0.5 degree C) Confusing display digits with accuracy
- Accuracy plus or minus 1 degree F (0.5 degree C) Assuming any thermometer qualifies
- Required range 30 to 120 degrees F (0 to 50 degrees C) Using a device verified only at room temp
- Verification interval At least every 12 months Skipping after a drop
- Sample completion Within 5 minutes of sampling Doing slump first and running long
- Reporting increment Nearest 1 degree F (0.5 degree C) Adding false decimals
The device may be a liquid-in-glass, bimetallic-dial, or electronic thermometer as long as it meets the readability and accuracy rules. The standard does not mandate one type; it mandates performance — readability to 1 degree F, accuracy to plus or minus 1 degree F, and coverage of the 30 to 120 degrees F range. A digital probe that only displays whole degrees is acceptable on readability but must still pass the plus or minus 1 degree F accuracy check during verification.
Verification documentation matters on the written exam and in real disputes. The technician should be able to point to a verification record showing the device was checked within the past 12 months against a reference whose calibration traces to a recognized standard. If a device is dropped, left in the sun, or returns a reading that disagrees with a second device, accuracy is "in doubt" and it must be re-verified before further use regardless of how recently it was last checked.
Timing and Where the Test May Be Run
The test may be performed in the sampled concrete, in the mixer or transporting unit, or in placed concrete as long as enough surrounding concrete is available. The controlling idea is that the sensing portion must be embedded in concrete and shielded from ambient air; a thin smear of concrete on a probe or a reading against a metal container wall is not a reliable concrete temperature.
Timing is the most commonly missed numeric. When temperature is measured from a sample obtained under ASTM C172 , the measurement must be completed within 5 minutes after the sample is obtained . The thermometer cannot sit in the bottom of a toolbox while the technician finishes slump first. Temperature equipment should be staged before sampling, especially in hot, cold, windy, or fast-paced placements.
Performance-exam success comes from calm setup: have the thermometer ready, know its verification status, insert it correctly, press concrete around the stem, wait for stabilization within the allowed window, read it while embedded, and record the result. The procedure is short, so mistakes usually come from rushing or assuming any quick number is acceptable.
Field memory list:
Confirm the device reads to 1 degree F and is verified within 12 months.
Start temperature work promptly after sampling and finish within 5 minutes.
Embed the sensor in concrete with the required cover to isolate it from air.
Wait for stabilization but stay within the maximum reading time.
Report to the nearest 1 degree F or 0.5 degree C without added precision.