Abstract

Ion diffusion through cement-based barrier is key to safe radionuclide transfer in intermediate radioactive waste disposal facilities. The purpose of this research is to elicit the behavior of ionic diffusivity and pore structure of hardened cement paste specimens for the barrier system when exposed to high temperatures (up to 80°C) for long periods (up to one year). The cement paste is made of an ordinary Portland cement base- and a low-heat Portland cement / fly ash / limestone filler (LF)system. The results of the adsorption isotherms of N2 and water vapor of the specimens exposed to limesaturated water of different temperatures, 20, 40, 50, 60, and 80°C, are presented, and their pore size distributions are analyzed by the Barrett-Joyner-Halenda method. The change of specific surface areas is measured and the influence of high temperature on the pore structure is discussed. Additionally, results of chloride ionic diffusivity test for the specimens after the high-temperature exposure are contrasted with the tendency of pore structure change. It is found that the LF system has much higher resistance to high-temperature exposure than ordinary Portland cement; however, temperatures greater than or equal to 60°C deteriorate the ionic diffusivity. These experimental results may indicate the ionic diffusivity of hardened cement paste can be influenced by the spatial electrical charge in micropores depending on the electrical charge of pore wall and the ion composition of pore solution.

Abstract

"jats:p"In this paper will be presented the influence of high temperatures on asphalt street pavement in terms of the influence of temperature on permanent deformations and thus the technical condition of the streets, comparable to the effects induced on extra-urban roads."/jats:p" "jats:p"Environmental factors are one of the mayn factors being assaulted in operation and road structures are very important in terms of the influence they can have on the state road transport technical infrastructure."/jats:p" "jats:p"Will be presented differences between urban road structures (streets) and extra-urban (road) both in terms of construction, the demands of traffic and environmental conditions to which they are subject."/jats:p" "jats:p"Road structures extra-urban and urban areas are required differently in terms of the environmental conditions of the location ambient different thereof, that is, when the streets they are inside localities and the built environment significantly affect road infrastructure, unlike in the case of roads where they are located just outside the settlements, reducing the effect of air currents accumulation pavement surface temperature."/jats:p" "jats:p"To demonstrate the influence of high temperatures on the pavement were conducted laboratory tests on asphalt mixtures in order to demonstrate the occurrence of reduction of physical characteristics, with adverse implications on the performance of applications similar to traffic. Document type: Article