Causes, Evaluation, and Repair of Cracks in Concrete Structures

Description

Cracks in concrete have many causes. They may affect appearance only, or they may indicate significant structural distress or a lack of durability. Cracks may represent the to talextent of the damage, or they may point to problems of greater magnitude. Their significance depends on the type of structure, as well as the nature of the cracking. For example, cracks that are acceptable for buildings may not be accept-able in water-retaining structures.Good crack repair techniques depend on knowing the causesand selecting appropriate repair procedures that take thesecauses into account; otherwise, the repair may only betemporary. Successful long-term repair procedures must addressthe causes of the cracks as well as the cracks themselves.

This report is intended to serve as a tool in the process ofcrack evaluation and repair of concrete structures.The causes of cracks in concrete are summarized alongwith the principal procedures used for crack control. Bothplastic and hardened concrete are considered. The impor-tance of design, detailing, construction procedures, concreteproportioning, and material properties are discussed.

The techniques and methodology for crack evaluation aredescribed. The need to determine the causes of cracking as anecessary prerequisite to repair is emphasized. The selectionof successful repair techniques should consider the causes ofcracking, whether the cracks are active or dormant, and theneed for repair. Criteria for the selection of crack repairprocedures are based on the desired outcome.Twelve methods of crack repair are presented, includingthe techniques, advantages and disadvantages, and areas ofapplication for each.

This chapter presents a brief summary of the causes ofcracks and means for their control. Cracks are categorized asoccurring either in plastic concrete or hardened concrete(Kelly 1981; Price 1982). In addition to the informationprovided herein, further details are presented in ACI 224Rand articles by Carlson et al. (1979), Kelly (1981), Price(1982), and Abdun-Nur (1983). Additional references arecited throughout the chapter.