| D-cracking is a progressive distress associated primarily with the use of coarse aggregates that deteriorate when critically saturated and subjected to repeated cycles of freezing and thawing. The objective of this thesis is to develop a suite of tests and criteria for accepting or rejecting aggregates that will be used in concrete exposed to freezing and thawing.; Condition surveys of concrete highway pavements were performed to document the field freeze-thaw performance of selected aggregate sources representing a range of frost resistance. Pavement cores were obtained for laboratory testing and evaluation, and coarse aggregates were obtained from the original sources for use in performing environmental simulation tests (i.e., variations of ASTM C 666 and the VPI single-cycle slow-freeze test) and correlative tests (i.e., absorption and bulk specific gravity, PCA absorption and adsorption tests, Iowa pore index test, acid insoluble residue test, X-ray diffraction analysis, X-ray fluorescence analysis, thermogravimetric analysis and the Washington hydraulic fracture test). Petrographic examination was also used to correlate the geological and engineering properties of aggregates to environmental and correlative test results.; The research program included: (1) the identification and classification of aggregates; (2) correlation of laboratory test results to field performance; (3) correlation of the results of correlative tests to the results of simulative tests; and (4) use of the cumulative results of these tests and the evaluation of field sections to develop an appropriate suite of freeze-thaw durability tests for accurately assessing the probable field freeze-thaw performance of any given aggregate as a function of its original geological origin and probable environmental exposure.; A suite of tests was developed to accurately assess the probable field performance of any given aggregate as a function of its original geological origin and probable environmental exposure. The petrographic examination was the first step used to identify aggregate composition and origin and provide a basis for the selection of subsequent durability tests. The battery of tests also included the Washington hydraulic fracture test, VPI single-cycle slow-freeze test and the rapid freezing and thawing test using procedure B and salt-treated aggregates. |
