First results of the investigation of the corrosion behavior of steel in concrete after local repair measures are described. The examinations in this research project refer to construction practice where local damage due to reinforcement corrosion, e.g., spalls and cracks, is repaired in the area of visible surface damage only. When dealing with damage in this way, the carbonated or chloride contaminated concrete is often not removed completely, thus avoiding stability problems with the structure. Following such a repair measure, reinforcement areas consequently remain, in which there is no guarantee of sufficient corrosion protection and which, therefore, are subject to a higher corrosion risk. With the help of macrocell current measurements between different steel electrodes embedded in concrete, the study investigated circumstances and extent of corrosion problems before and after local repair measures. Further investigation dealt with the measures that have to be taken to guarantee corrosion protection after local repairs.

In France, water towers, reservoirs, tanks, and basins constitute extensive facilities requiring inspection and maintenance. The survey recently conducted on the performance and durability of waterproofing in these structures is of considerable importance at the present time, with the publication of the new French professional recommendations, the revision of Section 74 of the CCTG (general technical specifications governing public contracts entered into in the name of the state), and the negotiation of future European Community regulations. This survey enables us to better understand existing facilities and to obtain precise information on such structures, with details on capacities, heads, and commissioning dates, but also on the selection of the initial waterproofing used, which may be a sealed structure itself or a support for waterproofing.

Current manufacturing practice used in the fabrication of concrete pavers produces a final product that has high density and strength, low permeability, and inadequate pore structure. Although high strength and low permeability should keep the pore structure from becoming critically saturated, lack of sufficient amount of air (entrapped and/or entrained) makes paving blocks potentially vulnerable to freezing and thawing damage. Presents experimental results relevant to the freezing and thawing performance of various concrete paving blocks using a standard accelerated laboratory test, ASTM C 666, Procedure A. The parameters investigated included bulk properties and weight loss. Test results indicate that ASTM C 666 can be successfully utilized to evaluate the relative performance of various block pavers. Weight loss correlates well with the cement content (aggregate-cement ratio) of the matrix. Minimum cement content, instead of minimum strength or maximum absorption, is the most suitable requirement for insuring a reasonable freezing and thawing resistance for concrete block pavers.

A joint project of the Reinforced Concrete Research Council (RCRC) and the U.S. Army Corps of Engineers Waterways Experiment Station (WES), covering four field exposure test programs at Treat Island, Maine, was initiated in the 1950s. Two of these addressed tensile crack exposure tests for reinforced concrete to determine the effects of severe natural weathering on the performance of stressed and tensile-cracked reinforced beams. The "Series B" test program, begun in 1954, consisted of 76 reinforced concrete beams. The test variables were location of the reinforcing steel in the concrete beam at the time of casting, its deformation patterns, and the degree of tensile stress. Condition surveys were carried out annually and stopped in 1979. The physical condition and state of corrosion of the ``Series B" beams were investigated by the authors in October 1989 after a period of 10 years of unattended exposure. The overall physical condition of the beams was evaluated as severely damaged, mainly due to the repeated cycles of freezing and thawing. The damage patterns for the yoked (stressed) and control specimens were distinctively different. Six out of the thirty-two sets of yoked pairs had failed, the failure of four sets took place after 1979. Corrosion of reinforcing steel in concrete is considered to be mainly a consequence of the physical deterioration of the concrete. The overall condition of the embedded steel was evaluated as reasonably good considering 35 years of exposure in a severe marine environment.

In Australia, the Cement and Concrete Association has sponsored a number of research projects addressing aspects relating to deterioration of concrete structures caused by corrosion of the reinforcement. The overall objectives of these projects were to identify the factors influencing steel corrosion and to quantify their effect on initiating corrosion and on the rate of corrosion. The ultimate objective was to provide practicing engineers with the relevant parameters that can be used in the design and specification of concrete structures to minimize the risk of corrosion of reinforcing steel. Reviews the major corrosion research carried out in Australia. Article attempts to correlate research findings to the conditions in practice and to quantitatively predict design life of reinforced concrete structures in an environment simulating severe exposure conditions in Australia. The design life predictions presented should be considered within the context of the assumptions and approximations made. Data presented in this paper showed that the influence of binder type is more in the medium-strength concretes in terms of time to potential jump (initiation) and corrosion rate (propagation). Therefore, it is recommended to optimize concrete mixture proportioning with respect to binder type in this range of concrete strengths to utilize the benefits possible from different binders.