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During the winter of 1980 the cooling tower portion of work on the Stoney Brook Energy Center, Ludlow, Massachusetts was stopped due to cementitious grout failure in the precast concrete joint connections. Each precast concrete tee was connected to another tee by a cementitious grout joint. The grout apparently foamed during the installation. It was reported by the contractor that the grout was installed under conditions of application favorable for proper usage as specified by the grout manufacture-The average compressive strenqth of the foamed portion of the grout was 400 psi (2 .8 MPa). The depth of the foamed grout varied from 2.5 to 4 inches (63-101 mm). Three very important factors influenced the selection of the replacement material : low substrate temperature during application, low temperature application ability and product curability at sub-zero degrees fahrenheit temperatures. After a thorough investigation by the contractor of epoxy and cementitious grout manufacturers, it became apparent only one company was capable of supplying a commercially available product able to meet the above stated application conditions. A patented two-component modified epoxy mortar was selected from a U.S. manufacturer. This report is broken down into eight categories: selection of repair material; epoxy mortar selection; surface preparation; equipment, mixing and installation; independent laboratory results; conclusions; and recommendations listing quality control measures to be followed by others attempting this type of repair.

This paper reports the structural investigation, concrete testing, and rehabilitation program for a concrete clarifier in a water treatment plant at Belle River, Ontario, Canada. This plant was constructed in 1945 with non-air entrained, site mixed concrete. Extensive concrete scaling and spalling, traces of leakage and random cracking were observed on the tank wall surfaces. Both analytical methods and in-situ testing were employed to evaluate the structural adequacy of the clarifier. removal of deteriorated concrete, Remedial works involving construction of an exterior semi-circular protective concrete wall with buttresses plus repairs to the interior wall were completed in July, 1981.

Essential steps in modifying structures for the purpose of adapting old buildings to new use are discussed in this paper. Eight basic steps are described: (1) pre-liminary site visit, (2) documentation of original design and construction, (3) identification of desired changes in the building, (4) identification of code requirements applicable to building alterations, (5) development of structural modi-fication schemes and preliminary cost estimates, (6) verifi-cation of "as is" condition, review of adequacy of proposed modification scheme and estimated cost, (7) completion of design and construction documents, including drawings and specifications, and (8)'coordination of engineering design with construction quality control and accommodation of possible need for design changes during construction.

This paper describes nondestructive evaluation (NDE) methods that can be used in assessing the condition of concrete and masonry materials and components in structures being rehabilitated or preserved. Metal reinforcement is also included. The appropriate use of NDE methods is discussed and a recommended approach to selecting NDE methods for specific situations is given. NDE methods are briefly described based on their principle of operation, information they provide, applications, expertise required to use them, and advantages and limitation to their use.

This paper describes the engineering procedures in the renovation of Kresge Auditorium which is located at the Massachusetts Institute of Technology in Boston. Described are inspection procedures used to determine any structural deterioration which may have occured since the building's inception. These procedures included visual inspection to determine cracking and other aspects which would possibly reduce the structure strength, pulse-echo test and chemical and petrographic tests of the structure's concrete as well as continuous monitoring of structure motions during remedial construction. To assist in this remedial work, a series of finite element analyses were performed to determine stress levels within the structure. These analyses considered initial construction stresses as well as increased stresses due to structure deterioration. Based on the above, a series of structural modifications were developed and implemented in the structure restoration.