Chloride Thresholds Research Articles

Author's reply to discussion of paper “Chloride Thresholds in Marine Concrete” by David B. Mcdonald

Author's reply to discussion of paper “Chloride Thresholds in Marine Concrete” by David B. Mcdonald

Discussion of paper titled “Chloride Thresholds in Marine Concrete” by Michael Thomas

Discussion of paper titled “Chloride Thresholds in Marine Concrete” by Michael Thomas

Chloride thresholds in marine concrete

This paper reports results from an ongoing study of the performance of fly ash concrete in marine exposure. Reinforced concrete specimens exposed to tidal conditions were retrieved at ages ranging from 1 to 4 years. Steel reinforcement mass losses are compared with chloride contents at the location of the bar for concrete specimens of various strength grades and with a range of fly ash levels. The maximum level of chloride that could be tolerated without significant mass loss due to corrosion was found to vary with fly ash content. This threshold chloride level decreased with increasing fly ash content; values obtained were 0.70%, 0.65%, 0.50% and 0.20% acid-soluble chloride (by mass of cementitious material) for concrete with 0%, 15%, 30% and 50% ash, respectively. Despite the lower threshold values, fly ash concrete was found to provide better protection to the steel under these conditions, due to its increased resistance to chloride ion penetration.

Canadian and Peruvian gustatory response to bitterness and salt in instant potato purée

Canadian and Peruvian taste detection thresholds for quinine sulphate and sodium chloride were determined in an instant potato purée. These data were compared with thresholds in aqueous solution to determine the extent of threshold modification. Both Peruvians and Canadians had very low thresholds for quinine sulphate in the purée (5 to 9 ppm), but higher thresholds for sodium chloride in the potato mixture (217 to 223 ppm). With the purée, quinine sulphate thresholds were six to eleven times higher, and sodium chloride thresholds two to three times higher, for Peruvians and Canadians respectively, than with aqueous solutions. Women were more sensitive to saltiness than men, but bitterness thresholds did not differ significantly by sex. Hedonic scores were not correlated to panelists’ thresholds for either tastant. Factors affecting threshold determinations and implications for cross‐cultural research are discussed.

Taste thresholds: quality specific variation with human aging.

Detection thresholds for each of the four basic taste qualities were obtained from 81 adults between 23 and 88 years of age. Sodium chloride thresholds show a small but significant increase with age, confirming the only previous observations derived from procedures that control for age-related changes in response criterion and salivary sodium. Quinine sulfate thresholds display a similar but weaker relation to age. Sucrose and citric acid thresholds are not significantly related to age. Citric acid alone shows a sex effect. Detection thresholds for the four taste qualities undergo different changes with age.