Shell Content
The term "shell" encompasses the preserved remains of various invertebrate marine creatures, both from freshwater and saltwater environments. This includes, but is not limited to, the shells of snails, conchs, limpets, turritellas, vermicularia, oliva, and bivalves.
The term "free shell" refers to the part of the coarse aggregate that remains on the 4.75 mm or 4.00mm sieve, consisting of loose, intact or fractured shell material with a ratio of maximum length to shell wall thickness greater than five to one.
Apparatus
Balance
Sieves
Oven
TEST METHOD: PREPARATION AND ANALYSIS OF FIELD SAMPLE FOR FREE SHELL CONTENT
Sample preparation
Begin by drying the field sample at a temperature of 110+5°C (230+9°F) until constant mass is achieved
Split the sample to the required test size
Weigh the test sample accurately and record the value to the nearest 0.1g
Perform sieving of the test sample using a mechanical shaker or hand, following the guidelines outlined in the test method. Additional sieves of appropriate size can be used to fulfill proper sieving requirements and avoid sieve overload
Test Method
Utilize visual determination to separate the free shell in the portion of the test sample retained on the 4.00mm or 4.75mm sieve, according to the definition given in the standard
Use calipers to ensure that the particle length to wall thickness ratio is greater than five to one
Determine the weight of the retained on the 4.00mm or 4.75 mm sieve sample identified as free shell and divide this value by the weight of the entire test sample to obtain the free shell content.
REPORT
Report the results with precision, rounding the total shell content to the nearest 0.1%.