ACI CLTT-2 case studies
ACI CLTT-2 · Put your knowledge to work in context.
The ACI Concrete Laboratory Testing Technician – Level 2 is the second tier of the American Concrete Institute's Laboratory Concrete Testing certification track, listed by ACI alongside the Level 1 credential and the Concrete Strength Testing Technician program. ACI describes its testing programs as assessing the knowledge and ability to perform, record, and report the results of concrete field and laboratory tests, so this credential targets technicians who already handle laboratory concrete work and want a recognized qualification for the tests they run and the results they report. The ACI CLTT-2 case studies are 5 cases and about 2,472 words.
1Oven-Dry vs. Saturated-Surface-Dry Basis in a Moisture Dispute
A ready-mix producer delivers coarse aggregate to a paving job. The supplier's shipping ticket states 0.8% absorption and 1.4% total moisture, and the batch plant used those values to adjust water.
464 words, about 2 min2Sieve Analysis That Fails a Gradation Band on One Sieve
A 20 kg sample of 19.0 mm nominal-maximum crushed limestone is reduced by quartering and sieved. Results (percent passing): 25.0 mm 100; 19.0 mm 96; 12.5 mm 58; 9.5 mm 41; 4.75 mm 12; 2.36 mm 6; 1.18 mm 4; 300 µm 2; 75 µm 1.1.
490 words, about 2 min3Slump Test Disagreement Between Two Technicians
On a bridge deck pour, technician A performs a slump test and reports 95 mm. Technician B, watching, says the result is invalid because A did not moisten the cone, and repeats the test, reporting 130 mm.
500 words, about 3 min4Cylinder Break Pattern and the Case for a Retest
A set of three 100 × 200 mm cylinders from a 35 MPa mix is tested at 28 days. Results: 31.2 MPa, 33.5 MPa, and 22.8 MPa.
515 words, about 3 min5Sampling a Stockpile for a Gradation Acceptance Test
A technician must sample a 4,000-tonne crushed-stone stockpile for gradation acceptance. The stockpile is a conical pile about 12 m high; the outer 0.5 m has visibly segregated, with coarse material at the base and fines near the top.
503 words, about 3 min