ACI Aggregate Testing Technician exam - what does the field performance component actually look like?
I'm scheduled for the ACI ATT exam next month and I'm less worried about the written portion than the performance component. I've been doing aggregate testing in the field for about 2 years but my company does mostly fine aggregate work, so my experience with coarse aggregate tests like the LA Abrasion and the sodium sulfate soundness test is limited. Those procedures show up in the ATT performance exam and I don't want to get caught fumbling through something I've only done a handful of times.
The written exam covers ASTM standards across sieve analysis, moisture content, specific gravity, absorption, and a handful of other procedures. I've been scoring around 78% on the practice questions I can find, which I'm told is comfortably above the passing threshold. The real concern is the performance portion - I've heard evaluators are strict about procedure sequence and that going out of order, even if you correct yourself, counts against you.
My plan for the next 4 weeks is to run through each performance procedure twice a week in our lab, treating each run as a timed mock exam. We don't have every piece of equipment on site so I'm borrowing time at a local ready-mix lab for the coarse aggregate procedures. That's costing me about 3 Saturday mornings but I think it's worth it.
What do evaluators in your area actually focus on most during the performance component? I've heard it varies a lot by region - some are strict on equipment calibration checks, others care more about sample preparation sequence. Any insight from recent test-takers would help.
The evaluator I had was almost entirely focused on sample splitting and sample size verification before any testing began. He failed one candidate in my group for using a sample that hadn't been verified with the balance before starting. Calibration and sample prep sequence are everything - don't rush past those steps even if you're confident.
The written portion at 78% practice scores should be fine - I passed the written with a 74% and that was enough. The performance is where people fail. Treat every step as if the evaluator doesn't know you've been doing this for 2 years - verify equipment, follow the procedure in exact ASTM sequence, don't skip steps you consider obvious.
I sat for ATT six months ago. The LA Abrasion test wasn't in my performance set - they don't test every procedure every time, the evaluator draws from a pool. But you still need to know all of them because you won't know in advance which ones get selected. I spent a lot of prep time on tests that didn't show up and almost got tripped up on fine aggregate sieve analysis which I'd considered easy.
For coarse aggregate specific gravity and absorption, make sure you know the SSD condition determination cold. That judgment call - when the surface is actually saturated surface dry rather than still wet or bone dry - is trickier than it sounds under test conditions with an evaluator watching. A lot of people second-guess themselves and waste time they don't have.