Frost Heave Laboratory Investigation on Crushed Rock Aggregates.

Crushed rock aggregates are widely used for transport infrastructure construction in Norway. During winters 2009/10 and 2010/11, differential frost heave severely affected the Norwegian transport network. Currently there is no system in the Norwegian road design to calculate expected frost heave from sub-grade and crushed rock aggregates. The segregation potential (SP) can be used to estimate heaving according to climatic data with the SSR model. Consequently, the frost protection of roads and railways project was created in part to improve knowledge about the frost susceptibility sensibility of crushed rock aggregates. The goals of this paper are to a) introduce the Norwegian University of Science and Technology (NTNU) freezing cell apparatus and laboratory methodology, b) present soil characterization and SP results of 7 different rock types, and c) discuss SP relationship with fine fraction content and mineralogy. A 150 mm diameter by 200 mm high multi-ring frost heave apparatus was used to perform the tests. Samples were frozen from top and hydraulic pressure other than cryosuction was avoided. Temperatures, heaving rate and magnitude, and water mass were recorded for the 96 hours duration of each test. A wide variety of rocks, including granitic gneiss, gneiss, anortosite, granodiorite, slate, gabbro, gneiss, and porphyr, was chosen. Fine fraction <63, <20, and <2 µm varies from 12.5% to 25.6%, 7.1% to 14.8%, and 0.53% to 2.45% respectively. The SPs varied from 60 to 197 mm2/°C·d. SP results are in accordance with value range showed by Konrad (2005), Konrad and Lemieux (2005), and Nurmikolu (2005) for granitic aggregates. SPs for the other rock type are proposed to be used as reference values. The SP as a function of fine content <2 µm calculated from the <80 µm fraction showed a trend of R2=0.84 for this study. [ABSTRACT FROM AUTHOR]