NAMIBIA: Sekelduin Substation

PROJECT DESCRIPTION: Nampower substation for line for supply from central Namibia

CEMENT USED:+-3000 cub including mortar mixes to date. Ohorongo CEMIR with 30% Fly Ash blend used. 30% Fly-ash was added to the concrete to increase the density and reduce permeability as well as cracking of concrete.

PROJECT ETA: Started July 2021 - Project is planned to be completed and then handed over to Nampower end February 2023.

AMOUNT OF CEMENT USED: 730 tons of cement and counting.

RECOMMENDED CONCRETE STRENGTH: 35MPa Concrete & Mortar

CONCRETE PLACEMENT: Due to confined space, distance to cast element and height, all concrete was placed using a mobile pump as well as crane with bucket.

WHAT WAS UNCOMMON ABOUT THE PROJECT?: Mortar was delivered in 6cube truck. An additive was added to allow longer open time and mortar could be used over 6 hours without hardening or effecting the mortar properties.

PROJECT CHALLENGES: Some of the biggest challenges on site was placing concrete with overhead crane and bucket. The discharge of concrete was very slow and trucks had to stand on site for extensive times with continuous monitoring. Sometimes went on late into the evening.