Kárahnjúkar Hydroelectric Power Station

The fill material of the 5 dams has a total volume of approx. 13’600’000 m³, which had to be prepared on site, then placed and compacted to achieve a watertight construction. The headrace tunnels were mostly excavated using a “full-face” tunnel boring system (TBM) with a diameter of 5.5 – 7.2 m; the others were built using the “drill and blast” method for cross sections of 5.8 × 5.8 m and 7.2 – 7.6 × 8 m.

A minimum 250 mm thick layer of shotcrete using Sigunit® accelerator was applied throughout the drives with additional rockbolts, steel ribs and even thicker layers of shotcrete applied in zones of more difficult geological conditions. For all of the concrete on the project Sika admixtures were used to ensure consistent performance and quality.

Under the prevailing harsh Icelandic environmental conditions the shotcrete admixtures Sigunit®-L53 AF (IS) and Sika® ViscoCrete®-SC 305 were also used to maintain the pumpability of the shotcrete. The sprayed concrete application equipment selected by the contractors included 8 Sika Putzmeister spraying systems, Sika PM®, plus 3 Aliva® shotcrete machines and pumps that were installed on the 3 Hardrock Robbins TBM’s. For the mass concrete on the dams the water reducing plasticiser Sika® Plastiment® LA-100 was used.

Sigunit®-L53 AF (IS)
Sigunit®-P1 AF
Sika® ViscoCrete®-SC 305
Sika® Plastiment® LA-100
SikaFiber® 65/35
SikaPM®-400 – Sika-Putzmeister spraying systems
Aliva®-278 shotcrete pumps
Aliva®-403 accelerator dosing unit
Aliva®-285 rotor machines