Some of the Indiana concrete pavements constructed within the last 10-20 years have shown signs of premature deterioration, especially in the areas adjacent to the longitudinal and transverse joints. This deterioration typically manifested itself as cracking and spalling of concrete combined with the loss of material in the direct vicinity of the joint. In addition, in some cases "bulb-shaped" damage zones were also observed under the sealed parts of the joints. The objective of this study was to investigate possible causes of this premature deterioration. To reach this objective, the characteristics of the concrete in and near the deteriorated joints were compared and contrasted to the concrete characteristics in the non-deteriorated sections of pavement. The study was conducted in two different phases (Phase I and Phase II), and the findings are presented as a two-part report. The investigation started with a detailed inventory of selected areas of affected pavements in order to identify and classify the existing types of distresses and select locations for collection of the cores. During the Phase I of the study a total of 36 concrete cores were extracted from 5 different pavements.. During Phase II of the study a total of 18 cores were retrieved from five different pavement sections and subject to examination. The cores were subjected to eighth different tests: air-void system determination, Scanning Electronic Microscopy (SEM) analysis, X-ray diffraction (XRD) analysis, sorptivity test, freeze-thaw & resonance frequency test, resistance to chloride ion penetration (RCP) test and chloride profile (concentration) determination. The test results identified several cases of in-filling of the air voids (especially smaller air bubbles) with secondary deposits. These deposits were most likely the result of the repetitive saturation of air voids with water and substantially reduced the effectiveness of the air voids system with respect to providing an adequate level of freeze-thaw protection. Specifically, it was observed that the existing air void system in the concrete from panels near the deteriorated longitudinal joint had neither spacing factors nor specific surface values within the range recommended for freeze-thaw durability. Contrary to this, nearly all the concrete in lanes without damage had an adequate air void system at the time of sampling. In addition, the affected concrete often displayed an extensive network of microcracks, had higher rates of absorption and reduced ability to resist chloride ions penetration. From the observation of the drains performed using the remote camera it was obvious that not all the drains were functioning properly and some were entirely blocked. However, more precise or direct correlations could not be made between the conditions of the drains and observed pavement performance.