Measurement and Modeling of the Ability of Crack Fillers to Prevent Chloride Ingress into Mortar.
A common repair procedures applied to damaged concrete is to fill cracks with an organic polymer. This operation is performed to increase the service life of the concrete by removing a preferential pathway for the ingress of water, chlorides, and other deleterious species. To effectively fulfill its mission of preventing chloride ingress, the polymer must not only fully fill the macro-crack, but must also intrude the damage zone surrounding the crack perimeter. Here, the performance of two commonly employed crack fillers, one epoxy, and one methacrylate, are investigated using a combined experimental and computer modeling approach. Neutron tomography and microbeam X-ray fluorescence spectrometry (μXRF) measurements are employed on pre-cracked and chloride-exposed specimens to quantify the crack filling and chloride ingress limiting abilities, respectively, of the two polymers. A two-dimensional model of chloride transport is derived from a mass balance and solved by the finite element method. Crack images provided by μXRF are used to generate the input microstructure for the simulations. When chloride binding and a time-dependent mortar diffusivity are both included in the computer model, good agreement with the experimental results is obtained. Both crack fillers significantly reduce chloride ingress during the 21 d period of the present experiments; however, the epoxy itself contains approximately 4 % by mass chlorine. Leaching studies were performed assess the epoxy as a source of deleterious ions for initiating corrosion of the steel reinforcement in concrete structures.
Effects of Initial Surface Treatment Timing on Chloride Concentrations in Concrete Bridge Decks
In consideration of concrete cover thickness and the presence of stay-in-place metal forms (SIPMFs), research was done to determine the latest timing of initial surface treatment applications on concrete bridge decks subjected to external chloride loading before chlorides accumulate in sufficient quantities to initiate corrosion of the reinforcing steel. Chloride concentration data for this research were collected from 12 concrete bridge decks located within the Interstate 215 corridor in Salt Lake City, Utah. Numerical modeling was used to generate a chloride loading function and to determine the diffusion coefficient of each deck. On the basis of average diffusion coefficients for decks with and without SIPMFs, chloride concentration profiles were computed through time for cover thicknesses of 2.0 in. (50.8 mm), 2.5 in. (63.5 mm), and 3.0 in. (76.2 mm). The results of the work show that the average diffusion coefficient for bridge decks with SIPMFs is approximately twice that of decks without SIPMFs and that, on average, each additional 0.5 in. (12.7 mm) of cover beyond 2.0 in. allows an extra 2 years for decks with SIPMFs and 5 years for decks without SIPMFs before a surface treatment must be placed to prevent excessive accumulation of chlorides. Although the data generated in this research are based on conditions typical of bridge decks in Utah, they clearly illustrate the effect of cover depth and the presence of SIPMFs. This information may be especially valuable to bridge engineers and managers responsible for programming surface treatments on concrete bridge decks.
Main tendencies of religious consciousness development in modern society
The article is devoted to the investigation of the tendencies of religious consciousness development in modern society. At the present stage of development religious consciousness, like any other social and psychological phenomenon, is undergoing significant changes. The development of religious consciousness at the present stage of society evolution leads to the development of common moral norms and requirements. There is a tendency to reduce human ties with the religious community as a translator of religious consciousness. It is possible to speak about the transformation of religious consciousness but not about its disappearance.