Purpose and scope The purpose of this report is to provide a source of information on the evaluation of concrete structures (except those subjected to seismic effects) prior to rehabilitation. This is of particular importance since there is a substantial difference between the complexity of rehabilitation design@ as compared with the design of a new structure. Evaluation of specialty structure types such as bridges@ dams@ and tunnels are considered beyond the scope of this report.The report is presented as a series of recommended guidelines@ based on experience drawn from existing sources and past investigations. Case histories are not given so as not to deviate from a guideline approach.(For case histories@ see ACI SP-85@ ACI SCM 21@ and Concrete International@ March 1993.) The guidelines given in this report are general in character@ but specific enough for use as a format to model an evaluation procedure for a structure.The report is presented in the order in which an investigation would normally be conducted. The first and the most important single effort in evaluation prior to rehabilitation is the ??preliminary investigation@?? as described in Chapter 2. After having the results of the preliminary investigation@ the detailed investigation can proceed@ if deemed desirable. Chapter 3 outlines the efforts required for the detailed investigation which generally consist of five major tasks: reviewing pertinent documents@ performing a field inspection and condition survey@ sampling and material testing@ evaluating and analyzing the information and data@ and preparing a final report. Chapter 4 identifies those documents and sources of information that would normally be reviewed during the evaluation. The efforts required in performing field observations to verify and assess the structural condition are described in Chapter 5. Chapter 6 provides information on practices and procedures for sampling and material testing@ including visual examination@ nondestructive evaluation@ and field and laboratory investigations. Chapter 7 contains discussions on review of all the accumulated information and data@ material and structural evaluation@ identification and evaluation of rehabilitation alternatives@ and costs. Guidelines for preparing the final report are presented in Chapter 8.