Free ACI Field Testing I Exam Flashcards

C172 sampling, C143 slump, C1064 temperature, C138 density/unit weight/yield, C231 pressure air, C173 volumetric air, and C31 making & curing specimens. All test FRESH concrete. C39 (compressive strength) is NOT included.

55 multiple-choice questions, closed book, 1 hour. Must score at least 60% on EACH ASTM method AND at least 70% overall. A high overall score cannot rescue one failed method category.

Closed book. Demonstrate six methods; C172 sampling may be described verbally or performed at the sponsoring group’s discretion. Incorrectly performing or omitting any required checklist step fails that trial. Certification lasts five years; renewal requires both exams again.

Collect at least two portions at regularly spaced intervals during the middle discharge. Sample after required water and admixture adjustments and mixing. Combine and remix the portions; avoid the first and last discharge.

15 minutes maximum between obtaining the first and last portions of a composite sample. Transport and remixing must be done as quickly as possible to keep the sample representative.

Begin within 5 minutes after obtaining the final portion of the composite sample. These quick tests must start fast before hydration and evaporation change the concrete.

Within 15 minutes after fabricating the composite sample. This ensures cast cylinders/beams represent the concrete at placement and are not affected by delay before consolidation.

At least 1 ft^3 (28 L). Smaller samples are allowed for routine slump, temperature, or air tests, but strength specimens require a full cubic foot to be representative.

Combine and remix portions only as much as needed for uniformity; protect against rapid evaporation and contamination. Do not add water to the test sample. Wet-sieve oversized aggregate only when the applicable test method requires it.

Frustum of a cone: 8 in. (200 mm) bottom inside diameter, 4 in. (100 mm) top inside diameter, 12 in. (300 mm) height. The large opening sits on the base plate.

Smooth, straight steel rod, 5/8 in. nominal diameter, with a hemispherical tamping end. Length must be at least 4 in. longer than the mold depth and at most 24 in.; for a 12 in. slump mold this is 16-24 in., not only two discrete lengths.

Fill in 3 layers, each about one-third of the mold's VOLUME (not height), and rod each layer 25 times. Layer heights are roughly 2-5/8 in., 6-1/8 in., then full 12 in.

Rod throughout the depth of each layer. The bottom layer is rodded without striking the base plate; the middle and top layers penetrate about 1 in. (25 mm) into the layer below.

Raise the mold vertically 12 in. in 5 +/- 2 seconds with no lateral or torsional motion. Slump = vertical distance from the original top of the mold down to the displaced original center of the specimen.

2-1/2 minutes from the start of filling until the mold is removed, performed without interruption. Exceeding this allows the concrete to begin setting and skews results.

Disregard a sheared trial and repeat on another portion of the sample. Two consecutive sheared trials indicate that the concrete probably lacks the plasticity and cohesiveness needed for this test.

C143 applies to plastic concrete with coarse aggregate up to 1-1/2 in. (37.5 mm). When larger aggregate is present, test the fraction passing that sieve after wet sieving under C172.

Immerse the sensor at least 3 in. (75 mm), with at least that cover in every direction. The container must also accommodate at least three times the nominal maximum aggregate size as concrete cover. Aggregate over 3 in. does not prohibit C1064; it may need up to 20 minutes for heat transfer.

For the ordinary procedure, leave the device immersed for at least two and no more than five minutes, then read it while still in the concrete. Large aggregate over 3 in. may need additional equilibration time.

Accurate to +/- 1 degF (0.5 degC) over 30-120 degF. Verified at least once every 12 months against a reference thermometer traceable to a national standard, and any time accuracy is in doubt.

No. If temperature is the only measurement, a C172 composite sample is not required. Concrete may be measured in transporting equipment or forms when the device has the required concrete cover.

No. C1064 measures temperature at the time of testing. Compare the result with the applicable project specification; the method does not itself impose one universal hot- or cold-weather acceptance limit.

C231 (pressure) is NOT valid for lightweight, highly porous, or air-cooled slag aggregate. Use C173 (volumetric / roll-a-meter) for those concretes — no aggregate correction factor is needed.

Type A relates pressure to a change in the water-column level above the concrete. Type B equalizes a known air-chamber volume at known pressure with the concrete’s air and reads the calibrated pressure gauge.

3 approximately equal layers, each rodded 25 times with the 5/8 in. rod. After rodding each layer, tap the bowl sides 10-15 times with the mallet to close rod holes and release trapped air.

Accounts for air trapped in the pores of dense aggregate that the meter reads but is not paste air. It is determined on the project aggregate and SUBTRACTED from the indicated air to get true air content.

Close the main air valve; open both petcocks and introduce water until air is expelled. Keep petcocks open while establishing and stabilizing initial chamber pressure. Close them before opening the main air valve to apply pressure to the bowl.

Lightly tap the gauge to stabilize the needle and read as specified. Report corrected air to the nearest 0.1% through 8%; above 8%, use half the smallest scale division. Rod the bottom layer through its depth without forcibly striking the bowl.

Perform the pressure-meter calibration/standardization test as often as necessary and at intervals not exceeding three months. Recheck doubtful equipment. Type A meters also require recalibration after an elevation change over 600 ft (180 m); this elevation rule does not apply to Type B.

Residue on the mating flanges or gasket can prevent a pressure-tight seal and invalidate the reading. Clean the sealing surfaces; do not assume every leak produces a predictable, correctable error.

A volumetric air meter ('roll-a-meter'). It works on ALL concretes including lightweight and porous aggregate because it relies on displacement and agitation, not pressure, so no aggregate correction is needed.

2 approximately equal layers, each rodded 25 times with the 5/8 in. rod. After rodding each layer, tap the bowl sides 10-15 times with the mallet to close rod holes and release trapped air.

Use the specified 70% by-volume isopropyl alcohol to suppress foam during initial filling, before setting the liquid to zero. Subtract the applicable alcohol correction from the final reading; calibrated cups of added WATER are added to the result.

First invert/shake until concrete is freed, then roll for about one minute and allow stabilization: no more than 0.25 percentage-point change over two minutes. Repeat rolling and compare readings; if a third reading is needed and still disagrees by more than 0.25 point, discard and retest with more alcohol.

Add water using the calibrated cup to bring the liquid into the scale range, and record the number of cups. Each full calibrated cup represents one additional percentage point of air. Include those cups in the final calculation.

C173 accommodates dense, lightweight and porous aggregate and needs no aggregate correction factor. It requires controlled inversion, rolling, stabilization and validity checks. Follow the complete C231 sequence too; do not assume a pressure test takes less than one minute.

Density (unit weight), plus calculated yield, relative yield, cement content, and gravimetric air content. Yield verifies that batch quantities match the mix design.

Density = net mass of concrete (filled measure minus empty measure) divided by the calibrated volume of the measure. Reported in lb/ft^3 (normal-weight concrete ~140-150) or kg/m^3.

When rodding, use THREE approximately equal-volume layers. Measures up to 0.5 ft^3 use 25 strokes per layer; nominal 1 ft^3 measures use 50. Tap sides 10-15 times after each layer. Do not borrow C173’s two-layer rule.

Slump < 1 in.: must use internal vibration. Slump 1-3 in.: rodding or vibration. Slump > 3 in.: rodding. Match the method to workability to avoid segregation or trapped air.

Yield = total mass of all batched materials divided by measured density (volume produced per batch). Relative yield = actual yield / design yield; < 1.00 means under-yielding (less concrete than designed).

Compare measured density to the theoretical air-free density computed from mix proportions; the percentage difference is gravimetric air. It is an independent check on C231 or C173 air results.

Determine calibrated measure volume from net water mass divided by water density at the measured temperature; verify at least annually. Use the required flat strike-off plate to leave the measure level full, then clean the exterior before weighing.

Common acceptance cylinders are 6x12 in. or 4x8 in. Cylinder diameter must be at least three times nominal maximum coarse aggregate size. Use beam dimensions and length meeting C31 and the intended flexural test; do not infer a beam size from the cylinder rule alone.

6x12 in.: 3 layers, 25 strokes each, 5/8 in. rod. 4x8 in.: 2 layers, 25 strokes each, 3/8 in. rod. Subsequent layers penetrate ~1 in. into the layer below; tap mold 10-15 times per layer.

Slump below 1 in. requires vibration; at 1 in. or more, C31 allows rodding or vibration. Both cylinder sizes use two layers when vibrated: one insertion per layer for 4 in. diameter and two for 6 in. Do not let the vibrator rest on the mold.

Initial curing up to 48 hours, on a level rigid surface free from vibration and protected from moisture loss. Temperature: 60-80 degF for f'c < 6,000 psi; 68-78 degF for f'c >= 6,000 psi.

After initial curing, maintain free moisture on cylinder surfaces at 73.5 +/- 3.5 F using a conforming moist room or water tank. Standard curing measures the concrete’s strength potential under controlled conditions, not the actual strength of the structure.

Do not transport until at least eight hours after final set. Transportation itself must take no more than four hours. Cushion against jarring and protect from freezing and moisture loss; four hours is not a deadline measured from demolding.

Standard-cured cylinders are used for ACCEPTANCE (per ACI 318 / IBC, tested per C39). Field-cured cylinders estimate IN-PLACE strength for form removal, shoring release, or post-tensioning — not for acceptance.