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Mr. Landau graduated from Harvard Business School and held positions of major responsibility in the textile field in Germany, Belgium, Canada and the United States. With a background in the global fiber industry, specializing in polypropylene since 1971 Landau introduced the U.S. product, Fibermesh, into the world-wide construction market. Since 1983, he has traveled extensively developing a sales and engineering organization supplying polypropylene fibers for use in concrete. Landau has participated as a speaker in many National and several International Conferences, including the July, 1984 Conference in Rio de Janeiro, Brazil, Rilem Conference in Sheffield, England in July, 1985, XIII Bienniel Conference in Brisbane, Australia, 1987, and the Concrete Society Conference in Hong Kong, July 1987.

In situ nondestructive evaluation techniques for estimating rebar corrosion, crack depth, deterioration due to microfracturing, and kinematics of crack nucleation in concrete structures are investigated. For corrosion monitoring, a half-cell potential technique is improved. Distribution of electrical potential on rebar surface is analytically determined from surface observation of concrete, based on a computer-aided CSM (charge simulation method) procedure. The depth of surface crack is evaluated by the ultrasonic spectroscopy. A reference curve determined from the ratio of peak frequencies is applicable to not only plain concrete but also reinforced concrete (RC) members. The amount of microcracks associated with the deterio-ration is estimated from AE (acoustic emission) activity during a uniaxial compression test of core sample. The occurrence of AE events is quantitatively analyzed on the basis of the rate process theory. A source inversion analysis of AE waveform is developed to obtain information on location, type, and orienta- ion of crack nucleation. Basic results of the above techniques are summarized and in situ applications are discussed.

The US Army Corps of Engineers recently completed the Repair, Evaluation, Maintenance, and Rehabilitation (REMR) Re-search Program. The primary objective of this six-year, $35- million research effort was to develop effective and affordable technology for maintaining and extending the service life of existing Corps civil works structures. Savings of over $40 million, or more than four times the funding, have already been reported from the use of technology developed in the Concrete portion of REMR. Development and application of some of the technology which resulted in savings are described herein. Examples of this technology include (a) identification of materials and methods which allow in situ repair of deteriorated mass concrete as an alternative to conventional concrete removal and replacement, (b) development of concrete mixtures containing antiwashout admixtures which have been used successfully in underwater repairs without the usual tremie seal, (c) design and installation of a precast concrete stay-in-place forming system for lock wall rehabilitation, including concepts for installation of the system in an operational lock, (d) development of stability criteria that eliminate the need for expensive structural rehabil-itation of aging concrete gravity structures, (e) development of a new procedure for anchor embedment in hardened concrete under submerged conditions, and (f) identification of repair materials with a cavitation resistance more than 25 times greater than conventional concrete with 9,000 psi (62 MPa) compressive strength.

Recently, deterioration of reinforced concrete structures has been an issue of concern, such that repair methods and repair practice have been studied by many organizations. In this study the flexural behavior of FRP reinforced concrete beams (FRPC beams) was studied. The experimental values of the tensile stress in the main reinforcement, the concrete crack width, and the center displacement of FRPC beam agreed well with the calculated values. The flexural behavior of repaired reinforced concrete beams (RRC beams) using FRP and polymer mortar was studied. The results showed that tensile stress in the main reinforcement, the concrete crack width, and the center displacement of the beam were decreased after repair work. The elastic theory of reinforced concrete was still effective on the repaired beam. The values of tensile stress in the main reinforcement, and the center displacement of the beam could be calculated.

This paper deals with a new type of semiprefabricated slab. The slab is made of precast thin slab stiffened by a set of folded wire fabric including cast in-situ topping concrete. This study covers both the salient features of design and construction of this flooring system and experimental work carried out to study the flexural behavior of the slabs cast using the system. The results of the experiment showed that composite precast slab consisting of the precast thin slab and in-situ topping concrete can be designed as a monolithic component.