Moisture Effects on Two Crushed Limestone Aggregates

Crushed limestone aggregates (CLA) are extensively used in civil engineering construction and are considered very competent and durable. However, its durability will depend on the limestone rock source used. There are a large number of limestone quarries currently active in Puerto Rico which involve several limestone formations, and types which can range from very competent, dense, and hard to considerably weathered, porous or even chalky limestone. This study involved evaluating durability characteristics, and possible short term degradation, of two CLA materials mined from two different quarries in PR representing different geologic formations. The durability assessment consisted in tracking variations of mechanical properties of CLA samples tested after different periods of submergence in fresh and salt water environments with a maximum submergence time of 150 days. The geotechnical tests included Slake durability, Los Angeles Abrasion, 1-D compression, and triaxial compression. For the most part, test results revealed only a slight degradation of the mechanical properties in both CLA materials after 150 days submergence, except for compressibility and Los Angeles abrasion where modest to medium degradation were observed. However, the results suggest both CLA materials remain reasonably competent after the 150 days of exposure to both fresh and salt water. Further assessment is recommended to evaluate possible long term degradation including tests on CLA samples with longer exposure times and environmental conditions.