ACI Aggregate Level 2 case studies
ACI Aggregate Level 2 · Put your knowledge to work in context.
The ACI Aggregate Testing Technician-Level 2 is one of the certification programs administered by the American Concrete Institute, listed on ACI's Certification Programs page under the Aggregate Testing category alongside Aggregate Testing Technician-Level 1. ACI describes its certification offerings as "designed to form a minimum qualification for personnel employed within the concrete construction industry," and examinations are delivered through an international network of sponsoring groups. The ACI Aggregate Level 2 case studies are 5 cases and about 2,573 words.
1Sieve Analysis Discrepancy on a Stockpile Sample
A technician reduces a 25 kg field sample of crushed limestone base course by quartering and runs a washed sieve analysis. 200 wash loss is 11.8%, and the gradation plots 6% below the lower limit on the No.
445 words, about 2 min2Moisture Content and Density on a Coarse Granular Base
A field technician is compacting a 200 mm lift of crushed aggregate base. The specified density is 98% of the maximum dry density from a modified Proctor (AASHTO T 180) on the minus 19 mm fraction.
569 words, about 3 min3Los Angeles Abrasion Result Outside Tolerance
A technician runs a Los Angeles abrasion test (AASHTO T 96, Grading B) on a crushed gravel source. The sample is prepared from material passing the 25 mm and retained on the 1.9 mm sieves, and the mass of the test sample before testing is 5,005 g.
553 words, about 3 min4Proctor Curve Shape and Optimum Moisture
A lab technician develops a modified Proctor curve for a well-graded sandy gravel base material. Five points are run at moisture contents of 4.0, 6.0, 8.0, 10.0, and 12.0%, giving dry densities of 2,050, 2,140, 2,190, 2,175, and 2,100 kg/m³ respectively.
518 words, about 3 min5Sampling Frequency Shortfall on a Base Course Lot
A base course lot of 1,800 m² is being placed in a single lift. The specification requires one field density test per 400 m² or fraction thereof, plus one gradation and one Proctor verification per 1,000 m² or fraction thereof.
488 words, about 2 min