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Frost Depth and Frost Protection Capacity of Crushed Rock Aggregates Based on Particle Size Distribution
A common road insulation practice in Norway is to use a layer of crushed rock material, which is called a frost protection layer (FPL). The current regulations allow a large variation of particle size distribution into this layer. This paper presents field investigations on frost insulation performance of crushed rock material with three distinct grading. A full-scale test site was built in Røros, Norway, with each FPLs composed of 1 meter of crushed rock aggregates and built as: Ro-3 section was a coarse dense-graded material (0/120 mm), Ro-1 section, a coarse open-graded material (40/120 mm) and section Ro-2, a fine dense-graded material (0/32 mm). The sections were monitored for two winters (2016–17 and 2017–18). The results showed a significant difference in frost penetration and capacities between the sections. For winter 2016–17, the frost depth reached 194, 136, and 175 cm in Ro-1, Ro-2, and Ro-3 sections respectively, for a surface freezing index of 22,630oC·h. For winter 2017–18, the frost depth reached 232, 171, and 209 cm in Ro-1, Ro-2, and Ro-3 sections respectively, for a surface freezing index of 36,683oC·h. The 0/32 mm material provided the best insulation capacity with a frost protection capacity of 443°C·h/cm. The frost protection capacity for the 0/120 and 40/120 mm material were of 253 and 85°C·h/cm respectively. The study showed that fine dense-graded material provided superior frost protection mostly due to the larger amount of water retained that increased latent heat. For similar road design and layer thicknesses, the coarse, well-graded material seemed to be the most cost-effective material adapted to Norwegian regions with F100 < 28,000°C·h. Coarse, open-graded material should be used in low FI areas, and convection effect should be taken into account.
Frost Depth and Frost Protection Capacity of Crushed Rock Aggregates Based on Particle Size Distribution
A common road insulation practice in Norway is to use a layer of crushed rock material, which is called a frost protection layer (FPL). The current regulations allow a large variation of particle size distribution into this layer. This paper presents field investigations on frost insulation performance of crushed rock material with three distinct grading. A full-scale test site was built in Røros, Norway, with each FPLs composed of 1 meter of crushed rock aggregates and built as: Ro-3 section was a coarse dense-graded material (0/120 mm), Ro-1 section, a coarse open-graded material (40/120 mm) and section Ro-2, a fine dense-graded material (0/32 mm). The sections were monitored for two winters (2016–17 and 2017–18). The results showed a significant difference in frost penetration and capacities between the sections. For winter 2016–17, the frost depth reached 194, 136, and 175 cm in Ro-1, Ro-2, and Ro-3 sections respectively, for a surface freezing index of 22,630oC·h. For winter 2017–18, the frost depth reached 232, 171, and 209 cm in Ro-1, Ro-2, and Ro-3 sections respectively, for a surface freezing index of 36,683oC·h. The 0/32 mm material provided the best insulation capacity with a frost protection capacity of 443°C·h/cm. The frost protection capacity for the 0/120 and 40/120 mm material were of 253 and 85°C·h/cm respectively. The study showed that fine dense-graded material provided superior frost protection mostly due to the larger amount of water retained that increased latent heat. For similar road design and layer thicknesses, the coarse, well-graded material seemed to be the most cost-effective material adapted to Norwegian regions with F100 < 28,000°C·h. Coarse, open-graded material should be used in low FI areas, and convection effect should be taken into account.
Frost Depth and Frost Protection Capacity of Crushed Rock Aggregates Based on Particle Size Distribution
Loranger, B. (author) / Rieksts, K. (author) / Hoff, I. (author) / Scibila, E. (author)
18th International Conference on Cold Regions Engineering and 8th Canadian Permafrost Conference ; 2019 ; Quebec City, Quebec, Canada
Cold Regions Engineering 2019 ; 169-176
2019-08-08
Conference paper
Electronic Resource
English