In marine environments, deterioration of concrete infrastructures under airborne chloride attack is a common problem, which raises the need for a reliable prediction model of airborne chloride penetration into concrete structures to evaluate the service life of concrete structures. This study proposes a time-dependent computational model for predicting the amount of airborne chloride ingress into concrete under actual environmental conditions. The proposed model calculates the amount of chloride penetration by considering the amount of advection and diffusion of airborne chloride on the concrete surface. To compute the amount of airborne chloride penetration, the proportion of dry and wet sections on the concrete surface is assumed, and to ensure accurate prediction of chloride penetration into concrete structures under actual environment conditions, the washout effect of rainfall is taken into account in the calculation. The proposed model was verified through comparison of the experimental and on-site measurement results.
Waste glass has potential for use in building materials, for example, as an aggregate replacement, a filler in concrete, or a cement replacement. Finely ground glass powder (particle size of less than 38 µm) can be used as a pozzolan material in concrete because of its high reactive silica content. This paper studied the properties of concrete containing finely ground glass powder (approximate particle size, 12-15 µm) of admixture Type D following ASTM C494. The fresh concrete's compressive strength, ability to resist chloride penetration, and free drying shrinkage were evaluated. The experiment showed that using 10% or 20% glass powder reduced the workability of fresh concrete and accelerated its setting time. However, concrete containing 10% finely ground glass powder exhibited greater compressive strength and improved resistance to the penetration of chloride ions than normal concrete and concrete containing fly ash at the same replacement level. Concrete with 10% glass powder also had lower shrinkage than normal concrete and concrete containing fly ash but higher shrinkage than concrete with 10% silica fume.
The deterioration of concrete structures in airborne chloride environments is a common problem, as attested by the large number of concrete structures in coastal areas that are in need of repair due to corrosion of steel reinforcement. Thus, to prolong the service of concrete infrastructure in marine environments, deterioration from airborne chloride should be carefully considered. However, the amount of airborne chloride is influenced by numerous factors including wind direction, wind speed, wave height, obstacles, and distance from the seashore, and the concentration of airborne chloride varies by time and location. Besides actual exposure conditions, chloride ingress depends also on the environmental condition. In order to design the concrete structures, one must consider the amount of airborne chloride, concrete qualities, and the environmental conditions. Consequently, this research aims to develop a comprehensive system that can predict chloride ingress in concrete structures by considering airborne chloride intensity at the specific locations and times, based on determination of the amount of airborne chloride generated by breaking waves and transported by wind flow. The proposed methodology can determine the chloride penetration into concrete structures in various marine environments. The numerical framework has been verified through on-site measurements to confirm its validity.
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