Grouting of Micropiles in Scandinavia

Use of micropiles has increased rapidly in Scandinavia. Applications of grouted micropiles cover underpinning works, construction of detached houses and soil nailing. Today, main part of Scandinavian micropiles are type of impact driven without grouting, when as grouting is common phase of installation for drilled micropiles. New codes of practice have been published recently in Sweden and Finland. A new approach for grouted impact driven micropiles has been made in the innovation of the CSG pile. Continuously shaft grouted or CSG micropiles have been grouted simultaneously during embedding of piles. Grouting has been implemented using pressure pumps as well as utilising self pressuring feature of the driving method. Steel micropiles have been driven down with steel stress of 100 to 400 MPa in each blow and a part of stress has been distributed to surrounding grout. Even 4 MPa or 40 bar pressure peaks have been monitored causing very efficient penetration of grout into surrounding soil material.