Laboratory tests were performed to investigate how sea ice abrades concrete and to clarify what the major factors are in estimating wear depth of concrete due to sea ice. This paper outlines a new apparatus developed by the authors for ice abrasion testing and the significant results obtained by using the apparatus.
The tests were carried out by changing various parameters which influence the wear rate of normal weight and lightweight concrete. They included type of aggregate, concrete strength, ice temperature, contact pressure, and relative velocity between ice and concrete. Among these, the ice temperature and contact pressure were found to be the most significant parameters. The results were summarized in chart form, as the first step toward realizing accurate estimation of wear rate.
The effect of surface treatment including polyurethane resin lining, resin mortar lining and polymer impregnation was also examined.
In the design of concrete structures for icy waters, sufficient consideration should be given to the durability of concrete against abrasion owing to sea ice. Such abrasion causes loss of effective thickness and strength of structural members which must bear enormous ice pressures.
Damage of structural members owing to erosion has been often observed in concrete structures such as bridge piers and offshore lighthouses in Bothnia Bay and Canada. The erosion of such structures, in most cases, is caused not only by sea ice abrasion but also by freezing and thawing. Since it is difficult in field observation to separate abrasion erosion from freezing and thawing erosion, laboratory testing, where freezing and thawing erosion can be eliminated, is considered a suitable method of studying abrasion problems.
Saeki et al conducted experiments on friction forces, which have been considered to be closely related to abrasion, between sea ice and various materials. Results of their study revealed that friction coefficients were mainly influenced by the following:
Relative velocity between sea ice and material
Sea ice temperature
Surface roughness of material
The authors have been studying abrasion problems for four years through a series of laboratory tests conducted by changing various factor including the three stated above.
In the course of these studies, the most influential factors and their effects on wear depth have been clarified. Further research to realize the quantitative evaluation of wear depth has been expected.
In an abrasion test for concrete from sea ice, actual abrasion mechanism should be accurately simulated. In order to reproduce actual abrasion environments in laboratory testing, the test apparatus is required to have special functions. H. Saeki, one of the authors, has conducted a past study on friction coefficient between sea ice and various materials. Based on this experimental study, the following characteristics are considered to be required for the abrasion testing apparatus for sea ice. (Available in full paper).
