111The behaviour of cemented soil and the role of cementation are reviewed based on experimental results. The review is presented in terms of geomechanics concepts in which the cemented soil may be modelled by elasticity and hardening plasticity concepts. No modelling equations are given, but the observed behaviour is analysed in view of the components entering into an elastoplastic model. These consist of an elastic range in stress space in which energy is not created or expended, a cementation yield surface, a 3D failure surface, a plastic potential, a yield surface and the associated plastic hardening law.

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With the climate change, Copenhagen has seen an increase in cloudbursts. During the cloudbursts, sewer systems overflow and result in flooded basements and overspill of untreated water into the harbour. A solution to the limited capacity is to make cloudbursts reservoirs to delay the rain water filling the sewer system. At Langelands Plads in Copenhagen, a reservoir has been established using the stonewool product Rockflow. The Rockflow is installed under two roads and a space used for recreational purposes. Based on monotonic and cyclic laboratory tests, material parameters and appropriate numerical model for the anisotropic material were established. In-situ measurements of the stiffness during and after installation at Langelands Plads consisted of plate load tests and falling weight deflectometer tests together with rutting measurements. The in-situ measurements were statistically processed and back-analysed to confirm the initial material parameters and model. Further, the in-situ measurements are ongoing at appropriate intervals to monitor the performance of the road.

Cement stabilization of very high plasticity organic soils (gyttja) near flood-prone areas, is a key to constructing water-retaining structures with optimized foundation works. The company Geo has documented the strength of cement stabilized gyttja samples from the area Jyllinge Nordmark in Denmark, for Keller Funderingsteknik Danmark ApS, who have carried out the stabilization. The strength was determined by Unconfined Compressive Strength (UCS) tests, with support of Consolidated Undrained Triaxial (CU) tests and field vane tests to determine undrained shear strength of the stabilized soil. In the laboratory, specimens were prepared with five different cement contents (60, 80, 100, 125, 150 kg/m3) and the strength determined after curing times of 7, 28 and 91 days. To document the in-situ strength and correlate laboratory and in-situ measurements, two UCS tests and three undrained triaxial tests were carried out on intact specimens taken from the cement stabilized soil. The investigation showed a good correlation between cement content, water content, curing time and compressive strength. Further, comparison with similar tests from Sweden, where cement stabilization is a far more common method, shows good correlation to the Jyllinge Nordmark results.

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