Durability and temperature-related characteristics of high-performance concrete
Abstract
In this study, high performance concrete mixtures made from locally available materials were developed and their performance compared against the performance of a conventional mixture. Significant reduction in chloride ion diffusion was observed and the ability of the high performance concrete mixtures to provide protection to reinforcing steel was superior. All of the high performance concrete mixtures contained ground granulated blast furnace slag and/or silica fume as partial cement replacements. Most high performance concrete mixtures contain higher cement contents and have lower water/cement ratios than conventional concrete mixtures. As a result, issues related to high internal temperatures are no longer confined to mass concrete. After a maximum temperature of 77.4°C (171°F) was recorded in a 457-mm (18-in.) thick beam produced with one of the high performance concrete mixtures developed in this study, it was decided that temperature effects in high performance concrete deserved more attention. To evaluate the effects of high internal temperatures in high performance concrete, a temperature matched curing enclosure was developed and built. The enclosure was then used to temperature matched cure strength and durability specimens that were later tested in conjunction with specimens cured under standard conditions. The temperature matched cured specimens were found to have reduced compressive strength, excessive scaling, and poor resistance against magnesium sulfate attack. However, their freeze-thaw resistance was improved. Although the maximum internal temperature in the temperature matched cured specimens did not exceed 75°C (167°F), the reduction in the 28-day compressive strength was as high as 2%. There appeared to be a somewhat linear relationship between the maximum curing temperature and reduction in compressive strength. Reduction in scaling resistance also appeared to depend of the maximum curing temperature. Lowering the temperature of the fresh concrete was effective in reducing the maximum curing temperature. When optimizing strength and durability is important, careful management of the internal concrete temperature is essential. Scheduling construction of high performance concrete members during the cooler periods of the year, when temperatures of fresh concrete are generally low, may result in significant savings and improve strength and durability characteristics of the concrete.
Degree
Ph.D.
Advisors
Olek, Purdue University.
Subject Area
Civil engineering
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