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These 10 free ACI-AGGREGATE-L1 questions are organized by exam domain, so you can see how each part of the Aggregate Testing Technician-Level 1 blueprint is tested. Reveal the answer and explanation under each question.
While sampling a flowing aggregate stream, a technician's receiver fills before it has crossed the entire stream. Material overflows during the rest of the pass. Which change corrects the sampling defect rather than merely collecting more material?
Correct answer: C - Replace the receiver with one that captures the full stream cross-section without overflow.
A production supervisor offers to run a loaded conveyor at crawl speed while a technician places templates across the belt and removes an increment. Before attempting this manual collection, the technician should:
Correct answer: A - Arrange a safe stopped-belt collection before placing templates or collecting the increment.
Wet sand arrives with free moisture coating the grains. A representative test portion is needed without first drying the sand. Select an appropriate reduction procedure.
Correct answer: C - Quarter the mixed sample and retain two diagonally opposite quarters, including their fines.
After washing an aggregate sample, a technician returns the material retained on the No. 200 sieve to the sample but discards the particles retained on the protective No. 16 sieve. The recovered sample is then dried to constant mass. What effect does discarding those particles have on the percentage finer than No. 200 calculated by washing?
Correct answer: B - It raises the percentage by counting retained aggregate as material lost in washing.
In an otherwise properly performed, dry-only sieve analysis, the total mass recovered from the sieves and pan is 0.18% below the original dry sample mass. The grading has not yet been compared with the specification. How should these data be handled?
Correct answer: A - Use the original dry mass; this discrepancy does not bar use for acceptance purposes.
Two sands have the same reported fineness modulus, 2.74, but substantially different percentages passing several individual sieves. A supplier argues that matching fineness moduli make the gradings interchangeable. Which statement addresses that claim?
Correct answer: D - Different gradings can yield the same cumulative-retention sum; individual sieve requirements still apply.
An aggregate-volume calculation requires relative density based on oven-dry mass and particle volume including water-permeable pores. An ASTM C127 test gives 3,750 g oven-dry mass, 3,825 g saturated-surface-dry mass in air, and 2,375 g net submerged mass. Which relative-density value belongs in the calculation, expressed to 0.01?
Correct answer: B - 2.59
Following the prescribed soak, a fine-aggregate sample initially retains its molded cone shape during surface drying. After further gentle drying and mixing, a correctly performed cone test produces the first slight slump. What should the technician do at this point?
Correct answer: C - Promptly obtain the saturated-surface-dry test portion for the pycnometer procedure.
A moisture test on sand gives these masses: empty pan, 200.0 g; pan plus wet sand, 1,460.0 g; pan plus sand dried to constant mass, 1,400.0 g. The sand's absorption is 1.2% of its oven-dry mass. What free surface-moisture percentage, on an oven-dry mass basis, should be used to distinguish water in excess of the SSD condition?
Correct answer: D - 3.8%
A correctly performed ASTM C40/C40M test produces a supernatant darker than the prescribed color reference after 24 hours. The supplier asks whether this proves that the fine aggregate will reduce mortar strength. The laboratory's defensible response is to:
Correct answer: B - Report the color warning and arrange ASTM C87/C87M testing of the effect on mortar strength.
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