INVESTIGATION INTO THE BEARING PROPERTIES OF HIGHWAYS WITH EPS LIGHT WEIGHT CONSTRUCTION MATERIALS IN THE SUBGRADE . THIRD INTERNATIONAL CONFERENCE ON BEARING CAPACITY OF ROADS AND AIRFIELDS. PROCEEDINGS, NORWEGIAN INSTITUTE OF TECHNOLOGY, TRONDHEIM, NORWAY, JULY 3-5 1990. VOLUMES 1-2

This paper investigates the design and construction of roads built on a subgrade consisting of at least 1 m of expanded polystyrene (EPS) on natural ground with low bearing capacity. The experiment was conducted in a concrete pit, 3.5 m deep, 7.5 m wide and 36 m long, where the ground water level could be set at will. The pit was filled with water sensitive soil (silt) at a high groundwater level. This subsoil was covered with a layer of sand approximately 10 cm thick in order to ease the placing of the EPS slabs and to ensure good soil contact. The EPS was produced with 2 courses of slabs, each 0.5 m thick making a 1 m thick embankment with a weight of 200 N per square metre. The slabs were placed in offset fashion so there were no joints immediately above one another. This embankment was covered with 6 different pavement types, each 12 x 3.7 metres in area. Each set of 2 adjacent sections were given a covering as follows: (a) 14 cm thick reinforced concrete slab with 20 cm and 28 cm thick gravel courses; (b) 34 cm and 42 cm thick gravel-sand courses placed in 2 layers; and (c) 20 cm thick cement stabilized sand, covered by a 14 cm or 22 cm thick gravel sand course. A 22 cm thick layer of asphalt was placed on the gravel surface in one set and a 14 cm thick layer on the surface of the other set. A brief report is provided of the placing experience, expecially the compactability of the unstabilized granular materials; and the bearing capacities of the gravel layer level and the road surfaces. The truck servicability of the gravel layer during construction was also investigated by simulating passes with a 10 t axle load by means of a loading plate. The bearing capacity of the asphalt layer was investigated by measuring deflection using: (a) a Benkelman beam; (b) a vibrator; and (c) a falling weight deflectometer; and the strain at the bottom of the asphalt layer passed over by a 100 kN axle load truck. (TRRL)