Among the highlights of the recent 56th annual convention of the American Concrete Institute held in New York City was a series of four related reports on successful techniques of restoring deteriorated concrete and a single paper covering broad aspects of the improvement of concrete through vibration. Listed among the advantages of consolidating concrete by vibration were the following: lowered cost of concrete through ease of placement and by reduced cement content; greater concrete density and homogeneity; greater strength ; improved bond with reinforcement; greater bond at construction joints; greater durability; and reduced volume change or shrinkage. These points were emphasized under the heading of conventional techniques of repairing concrete: good concrete repair or restoration must be thoroughly bonded to the older concrete; must by sufficiently impermeable to prevent moisture reaching underlying older concrete; must, after drying, be free of shrinkage cracks through which water could reach the supporting concrete; must be resistant to freezing where this is a factor in weathering; and should match surrounding concrete surfaces. On new or restoration work, all unsound concrete should be removed completely. It was also recommended that excavations be shaped so as to make the replaced material as secure as possible, and that surfaces be cleaned and moistened for maximum bond. Also discussed was the prepakt method. Prepakt is essentially a concrete of gap grading which is produced by first placing the coarse aggregate in the forms, and then pumping a sanded grout, sometimes referred to as intrusion mortar of prepakt grout, into the voids of the aggregate mass. In the repairs of many old stone masonry and concrete structures by the prepakt method, neat cement grouting is also carried out for the purpose of improving structural stability and reducing leakage.