ICE ABRASION DATA AT LAOBORATORY AND FIELD EXPERIMENT

Eric Acheampong 2nd year master student, Polytechnic Institute Far Eastern Federal University, Russia, Vladivostok e-mail: achiampong.er@students.dvfu.ru Scientific adviser: Uvarova T.E., Ph.D., professor, Department Marine Arctic Technologies Far Eastern Federal University Russia, Vladivostok ICE ABRASION DATA AT LAOBORATORY AND FIELD EXPERIMENT Abstract: For the last decades, the performance of concrete structures under severe marine environmental conditions has gained considerable attention. There are still a number of unknown factors related to design and material selection of concrete structures exposed to ice abrasion. The amounts of published data on this subject are relatively few and it is the aim of this document to collect and present some of these in terms of abrasion rates/depths, together with the material parameters of both ice and concrete. The objective is to identify the abrasion data and the differing exposure conditions as objectively as possible without going detailed into any models, in order to draw cross over conclusions with respect to wear rates and possible materials effects and to prepare for a continued study on the subject. The fundamental mechanism behind the ice abrasion of a concrete structure is more complex than barely the force of friction between moving ice and concrete. Field investigations and laboratory tests suggest that the observed abrasion is a result of the combination of environmental causes together with the ice impact forces Key words: Ice abrasion, Concrete, Laboratory, Field, Experiment. The sea ice properties range from sheet ice to unconsolidated pressure ridges to multi-year consolidated floes and ridges. The ice exerts its force in a variety of different modes, depending on the structure’s geometry and the ice parameters involved. Failure modes differ between crushing, flexure, buckling and shear. The overall force is limited by the driving force of the ice sheet behind the largest feature that can hit the structure without failing. It is observed that larger contact areas fail at lower unit forces, whereas 1 smaller faces fail at higher unit forces due to confinement and homogeneity of the ice. Local ice forces are limited only by the crushing strength of the ice and might be increased by a factor of 3 or more compared to the uniaxial strength, due to confinement. The effective strength is also dependent on temperature, salinity, crystal orientation and strain rate. It is generally accepted that these high local unit forces will occur only over limited areas and they will decrease significantly as contact area increases. The ice movement, caused by wind, currents and thermal expansion/contraction are the fundamental driving forces behind the phenomenon of ice abrasion. In rivers, lakes and oceans where periodic ice floes occur, concrete structures such as e.g. bridge piers, guide walls, docks, lighthouses etc. experience damage at or near the waterline due to impact with ice floes. Moving ice has, in extreme cases, been known to remove all of the concrete cover at or near the waterline for marine structures. 2 Author Abrasion/ Abrasion rates Huovinen 22-39 mm Field (1990) after 22-24 years (mean, all faces) > 25 mm 2,5 - Huovinen 11 mm 3,2 - 7 Lab (1990) mm No visible Malhotra Field (1996) abrasion observed after 7 years of exposure. Material Parameters Exposure Exposure (lab/field) Combination of At water level: fc = 35-46 Lighthouses Mpa 1,5m above WL: fc = freezethaw cycles and in the Gulf of Bothnia moving ice 65-80 MPa Lab, abrasion 50 freezethaw cycles LWA, fc=41-42 MPa machine and 10 min in abrasion ND1, fc=68-98 MPa ND2, fc=76-81 Mpa, blast machine (rotating cutter) furnace slag cement 12 panels “Very severe LWA: fc = 37-45 MPa ND: mounted in a exposure, included fc = 42-56 MPa Steel freeze-thaw cycles, ice Fibers (SF): 50kg/m3 w/c dock at Nanisivik abrasion, ice impact, ratio: 0,37- 0,42 and sea water attack. (73° North), 3 Observation Ice conditions Largest abrasion rate observed 0,1- 0,3 m below water level No ice. No description of the ice conditions. Test panels were in good to excellent Baffin Island, Canada Field study of More than 30 light houses examined in 1983-84 conditions after 7 years of exposure. Local corrosion of the steel fibers. Abrasion depths increased further north (more severe ice conditions). No abrasion in areas where the level ice thickness sea ice block was 80 mm wide, 50 to 100 mm high and 700 mm long. a temperature of - 20°C with an ice pressure of 1 MPa and an ice speed of 50 mm/sec. Janson Field (1988) Abrasion depths: 0-140 mm Abrasion rates: 0,2-7,0 mm/year ND (rounded shape) fc = 40 MPa Cement: 300-400 kg/m3 Additives: Air- entraining agent (after 1965) Location in Baltic Sea with low salinity, hence strong ice compared to Arctic seas (first year ice 4 Itoh, Lab (1988, 1994) Hanada Lab (1996) Abrasion rate (steady state): 0,05 mm/km for ice parameters given under “exposure” Abrasion depth: r v S S = ⋅σ ⋅ L Assume: r S = 0.0178 σ v = 1 MPa L = 1000 km Abrasion ND, fc = 57 Mpa LWA, fc = 70, 57, 35 Mpa Dmax = 25 mm Ice velocity: 5 cm/sec Ice temp: -20 ºC Contact pressure: 1 MPa N.A. Sea ice: 3-5 ppt salt Ice velocity: 5 cm/sec Ice temp: -10ºC Contact pressure: 1 MPa 5 Completely exposed aggregates made by cutting the top surface by 6- 10 mm never exceeded 0.3m Abrasion rate of concrete due to sea ice is mainly determined by the contact pressure and the ice temperature. Study of ice abrasion rates of different aggregate stones and a single concrete sample. depth: = 17.8 mm Approx. 10 mm estimated by size of exposed coarse aggregates (app.7 years after opening of bridge) Mean abrasion rate: 2 mm/km Sandwell (2003) [ 1,p. 6] Fiorio Lab (2005) fc = 90 MPa w/c = 0,25 Fly ash + silica fume High Performance Concrete (HPC) Design Lifetime: 100 years fc = 24.8 MPa w/c = 0.6 Portland CEM I 42.5 Aggregate: Fine sand (0.2 – 0.6 mm), coarse sand (3 – 5 mm) Gulf of St Laurent/ Northumberla nd strait/Canada Confederati on bridge piers Contact pressure ice/concrete: 0.25 – 0.80 MPa Lab, Abrasion/ friction tests by a shearbox machine Based on photos in Sandwell project facilities design report for Sakhalin II, Phase II Laboratory grown S2 columnar freshwater ice (Dgrain = 8 mm) Diameter: 60 mm, Height: 96 mm. Contact pressure ice/concrete: 0.25 – 0.80 MPa. 6 Ambient temperature: - 10 °C (+/- 0.5 °C). Sliding velocity: 1.67x10-6 – 1.67x10-4 m/s Summary of ice abrasion data from various laboratory and field experiments, listing key parameters with emphasis on exposure conditions and concrete material parameters. Ice conditions are also presented for the experiments where these are available. 7 Discussions and conclusions Itoh et al. (1988 & 94) An Experimental Study on Abrasion of Concrete Due to Sea Ice/ Estimation Method for Abrasion of Concrete Structures Due to Sea Ice Movement [2, p. 8]  With the given test conditions it seems that the abrasion rate depends neither on the compressive strength of the concrete nor the kind of concrete aggregate.  It was suggested that the abrasion rate of concrete is mainly determined by ice temperature and contact pressure.  Results of concrete abrasion due to sea ice movement. The study concluded that failure modes of ice sheets are crushing with radial cracking. The abrasion depth of the concrete is mainly governed by the ice parameters; contact pressure, temperature, and sliding velocity. Hanada et al. (1996) Abrasion Rate of Various Materials Due to the Movement of Ice Sheets [3, p. 8]  The observed ice abrasion rates of rock are proportional to the sliding distance of the ice.  The abrasion rate differs significant depending on the type of rock  Abrasion rates of sandstone and andesite are approximately 1/3 of that of concrete.  The smaller the grain size, the smaller the abrasion rate (related to surface roughness).  The higher uniaxial the compression strength of a rock, the higher the ice abrasion resistance. Malhotra et al. (1996) Manufacture of Concrete Panels, and Their Performance in the Arctic Marine Environment [4, p. 8]  It was concluded, after both svisual and micro structural examination that the concrete test panels after seven years of exposure in extreme exposure conditions were Журнал «Трибуна ученого» Выпуск 06/2022 https://tribune-scientists.ru 8 in good to excellent conditions. It was observed some local corrosion of the steel fibers for the fiber-reinforced concrete panels. Janson (1989) Field Investigation of Ice Impact on Lightweight Aggregate Concrete [5, p. 9].  It is assumed that the ice concentration needs to be very high in order for abrasion to occur, as this gives a sufficient high pressure between the ice and the structure. This in addition to the ice thickness and ice strength are considered to be important parameters when evaluating abrasion of concrete by sea ice movement. Huovinen (1990) Abrasion of Concrete by Ice in Arctic Sea Structures [6, p. 9].  The most important mechanical factor of the concrete with respect to resistance against ice abrasion is the compressive strength, which should be at least 70 MPa to secure a good resistance against abrasion.  The concretes with water/cement ratio no higher than 0.30-0.35 showed a good resistance against abrasion.  Normal weight concretes containing silica fume and blast furnace slag showed both a higher strength and a higher abrasion resistance than lightweight concrete with blast furnace slag.  Increasing the maximum size of the aggregates also contribute to an increase in the abrasion resistance of concrete.  The local ice loads acting on protruding aggregate stones are considerably greater than the uniaxial compressive strength of the ice. Fiona (2005) Wear characterization and degradation mechanisms of a concrete surface under ice friction [7, p. 10].  Higher Abrasion rate of 20 mm/km than what is observed in other comparable studies be caused by the use of small sized aggregates in the micro concrete. Discussions Журнал «Трибуна ученого» Выпуск 06/2022 https://tribune-scientists.ru 9 In the majority of the ice abrasion studies presented in this overview, the significance of the ice conditions is emphasized, with ice temperature and contact pressure as the two most essential. Several of the tests show little or no difference of the wear resistance for different concrete qualities. Exceptions are Hanada (rock) and Huovinen (concrete) who both concluded that the ice abrasion resistance was improved by increasing the material compressive strength. Conclusion  The phenomenon of concrete abrasion due to sea ice movement is complex, involving different mechanisms and parameters. From the previous studies on the subject there have been somewhat scattered conclusions, and various methods of estimating the rate of abrasion have been proposed. In general it seems that:  The rate of abrasion increases with increasing ice contact pressure and decreasing ice temperature. Ice sliding cause more abrasion than ice crushing.  The ice abrasion is reduced with increasing material strength as observed in laboratory tests on rock and field tests combined with modelling of concrete.  Using cement replacements like silica fume and blast furnace slag has shown a positive effect on the amount of abrasion. References: 1. Sandwell (B. Maddock) Technical Memo TM 107 Sakhalin II, Phase II Project Facilities Design (2002). 2. Itoh, Y., Yoshida, A., Tsuchiya. M., Katoh, K., Sasaki, K., and Saeki, H. (1988) An Experimental Study on Abrasion of Concrete Due to Sea Ice. Presented at the 20th Annual Offshore Technology Conference in Houston, Texas, May 2-5, 1988. (OTC 5687). Pp. 61-68. 3. Hanada, M., Ujihira, M., Hara, F. and Saeki, H. Abrasion Rate of Various Materials Due to the Movement of Ice Sheets. Proceedings of the Sixth (1996) // International Offshore and Polar Engineering Conference, Los Angeles, USA May 26- 31. 1996. Журнал «Трибуна ученого» Выпуск 06/2022 https://tribune-scientists.ru 10 4. Malhotra V.M., Zhang M.H., Sarkar S.L., (1996) Manufacture of concrete test panels, and their performance in the arctic Marine Environment, 3rd CANMET //ACI Int.Conf.Perf. of Concr. Marine Environm., Spec. Vol Odd E. Gjørv Symposium. Ed. P.K. Mehta. Рp. 55-81. 5. Janson J.E. Report No. 3, Results from the winter season 1988-1989, Conclusion after the three winters 1986 - 1989. Joint Industry Study, Field Investigation of Ice Impact on Lightweight Aggregate Concrete, VBB. 6. Huovinen S. Abrasion of concrete by ice in arctic sea structures. VTT Publications 62, (Doctoral thesis), Espoo, 1990. 110 p. 7. Fiorio B. Wear characterization and degradation mechanisms of a concrete surface under ice friction // Construction and Building Materials. 2005. Volume 19. Issue 5. Рp. 366-375. Журнал «Трибуна ученого» Выпуск 06/2022 https://tribune-scientists.ru 11