Effects of High Temperature and Cooling Pattern on the Chloride Permeability of Concrete

Abstract

Concrete structure is frequently subjected to the fire attack, whereas the permeability of concrete with fire-damage has received little consideration. is paper aims to investigate the chloride permeability of plain concrete and recycled aggregate concrete (RAC) with fire-damage, and the effects of various cooling patterns and recuring treatment on the chloride permeability are also studied. e results manifest that the elevated temperatures result in an increase in the fire-damage and chloride permeability of concrete, and that the increase becomes more obvious with the temperature above 400°C. Attributing to the water-cooling which provides a recuring environment, the chloride permeability after water-cooling is lower than that after air-cooling when the temperature is 200°C. Whereas when the temperature is above 400°C, the chloride permeability after water-cooling becomes higher than that after air-cooling, due to an extra damage that the water-cooling produces. e recuring treatment can reduce the chloride permeability of concrete with fire-damage, and the reduction becomes more significant when the concrete suffers a serious fire-damage. Exposing to the same condition of high temperature, the addition of recycled aggregate (RA) further boosts the fire-damage and chloride permeability of concrete. Particularly, the chloride permeability increases with the increasing of RA replacement ratios, linearly, and the increased temperatures further lead to an increase in the slope of the fitting straight line.

Anticorrosion Behaviour ofRhizophora mangleL. Bark-Extract on Concrete Steel-Rebar in Saline/Marine Simulating-Environment

“…In the past decade, numerous studies have deliberated on corrosion problems that are encountered from the in-service environments for steel-reinforced concrete applications [9–30]. These studies lend supports to the knowledge that the environments for steel-reinforced concrete attacks constitute the acidic [9, 12, 16, 30], alkaline [11, 15, 17, 23] and neutral [14, 18, 29] media, wherein environmental agents such as carbonation [20, 25, 28], chloride ions [10, 19, 21, 24], and sulphate ions [9, 13, 17] effects are indicated for the corrosion degradation mechanisms against steel-in-concrete. These have engendered monitoring techniques [26, 27] and solution approaches [20, 22, 29], over the years, for assessing and/or addressing different modes of reinforcing-steel corrosion in concrete.…”

Effects of an Applied Load on the Chloride Penetration of Concrete with Recycled Aggregates and Recycled Powder

“…e chloride ion diffusion behavior in the saturated concrete can be described by Fick's second law, as shown in equation 3, while the force of chloride diffusion is mainly provided by the difference in chloride concentration; moreover, the chloride diffusion coefficient can be obtained by the data fitting for the chloride ion content [5,42,43]:…”

“…[1][2][3]. Acting as the most important indicator of durability, chloride attacks frequently cause the steel to corrode in reinforced concrete and thus decrease the service life of the concrete structure [4,5]. About 80% of the structural failure was caused by the chloride penetration in the reinforced concrete according to the statistics [6].…”

Study on spalling and cracking behavior of MWCNTs concrete exposed to high temperatures

“…Therefore, after high temperature and cooling, there is not only a temperature gradient inside the specimen, but also a humidity gradient inside the water‐cooled specimen. The higher the temperature, the greater the humidity gradient and temperature gradient, the greater the failure stress, and the more serious the cracking and spalling of concrete specimen 13,14,16 . In addition, the higher the relative humidity, the less the water migration, the smaller the shrinkage deformation, and the slighter the possibility of cracking 15,17 .…”