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The pollution of water through release of hydroxyl ions from freshly cast concrete exposed to water can have a detrimental effect on aquatic life by causing a rise in pH. The concentration of hydroxyl ions leached from concrete can be affected by a number of factors. A detailed study has been undertaken to ascertain the effect of parameters such as flow rate, age of concrete after exposure, air quality, cement type, surface area and the volume of concrete. This paper presents the results of the experimental programme and a predictive model for change of pH of water after exposure to freshly cast concrete. Analysis of the results showed that the flow rate was the most significant factor in both the peak pH observed and the time to the peak pH. The volume of the sample was also identified as being a significant factor in the peak pH. [ABSTRACT FROM AUTHOR]

When concrete structures--such as pier supports--are placed in water, they can have a detrimental effect on the surrounding environment by causing the pH to rise. This rise in pH can harm and kill animal and plant life. The concentration of hydroxyl ions leached from concrete can be affected by a number of factors, including cement type, shape of structure, ratio of surface area and volume, and the low of the water. This paper presents the results of a research project that investigated three mixtures: 100% ordinary portland cement (OPC), 30% pulverized fly ash (PVA), and 65% ground-granulated blast-furnace slag (GGBS). Tests were conducted in both stagnant and lowing water using a range of specimen geometries and sizes. The results showed that the mixture, volume/surface area, and geometry of the specimen can affect both the rate of leaching and the cumulative number of moles of hydroxyl ions leached. [ABSTRACT FROM AUTHOR]

This paper reports the results of an experimental program to investigate the changes in the bond characteristics of deformed mild steel reinforcing due to chloride-induced corrosion. The principal parameters investigated are the cover depth, bar diameter, degree of corrosion, and the surface crack width. The results show a strong relationship between the average surface crack width and the average bond strength; the degree of corrosion does not demonstrate such a clear relationship. The bars with a 1 C/Φ (cover/diameter) show an initial increase in bond strength at the first visible crack; no similar initial increase is observed for the bars with 3 C/Φ. The bottom-cast bars display a higher bond strength with no corrosion, but a similar bond strength is observed for both top- and bottom-cast bars once cracking is observed. [ABSTRACT FROM AUTHOR]

Investigates the effect of corrosion attack on the mechanical properties of embedded reinforcement through physical tests on bars with simulated and real corrosion damage and through a simple numerical model. Possible impairment of structural capacity through loss of bar section and loss of bond between reinforcement and concrete as a result of longitudinal cracking; Suggested guidelines on assessment.