KlimaGrunn | New laboratory procedure presented at Geotechnics Day

On Friday, November 26, the new laboratory procedure was presented at the Geotechnics Day, which brings together the entire geotechnical professional community in Norway. The goal of the new procedure is to unify, improve and eventually replace the two existing Norwegian procedures for binder stabilization of loose materials, such as quick clay.

“Which of the current procedures is used varies between different actors, and the execution of the procedures also varies. As a result, results from different laboratories cannot be compared directly,” explains Tonje Eide Helle from Multiconsult. She is project manager for the supplier side in the innovation partnership KlimaGrunn.

KlimaGrunn is an innovation project funded by Innovation Norway and consists of the Norwegian Public Roads Administration, Bane NOR and Statsbygg on the client side, and Multiconsult, Norcem, Catutus Geo and Argeo on the supplier side. The main purpose of KlimaGrunn is to contribute to reducing greenhouse gas emissions from large developments by optimizing the amount of binder in ground stabilization.

New equipment and new recommendations

A central part of KlimaGrunn is to develop a new laboratory procedure, including the development of new equipment. The equipment should ensure homogeneous samples and constant volume in the samples during curing to achieve a predetermined density. Curing and temperature have also been changed in the new procedure since the temperature at which the samples are cured is crucial for the strength achieved during the curing time. Field measurements have also shown that the temperature in the ground increases after installation of binder-stabilized piles, and that it often remains higher than normal for several months after installation. The strength therefore increases faster in the field than in laboratory-prepared samples, which according to current procedures are stored cool. In KlimaGrunn's new procedure, it is therefore recommended to cure the samples at 20 °C.

Better agreement between lab and field

The laboratory results form the basis for the development of correlation models for the prediction of strength and stiffness in binder-stabilized loose materials. Sensor technology and seismic are used to monitor the curing process in the field and changes in shear wave velocity over time. Field data is then compared with laboratory results so that the strength and stiffness of installed binder-stabilized piles can be predicted.

“Better agreement between the strength achieved in the laboratory and in the field will help optimize the amount of binder for local ground conditions. This can reduce greenhouse gas emissions associated with ground reinforcement with binders,” explains Helle.