Keystone retaining walls

The system

Keystone units are large-format concrete masonry blocks with fibreglass pins that lock each course to the one below and set the batter automatically. The face is available split for a natural stone look or flush for a clean architectural line, in a range of colours. Behind the face, the blocks are backfilled with drainage aggregate and, for taller walls, layers of geogrid are laid into the compacted fill to tie the wall mass back into the bank.

Where we have used it

Keystone has carried some of our biggest subdivision programmes: staged estate walls for Stockland with Daracon and Burton, a charcoal flush-face wall for Burton at Prestons, and a three-metre reinforced earth wall at St Luke's Grammar in Dee Why matched to the school's colour scheme. It also went into the Keystone and crib wall combination beside Sefton station on the Southern Sydney Freight Line.

Design and construction

We design the wall section to the geotechnical report, prepare and compact the base, then lay, pin and backfill course by course with the geogrid placed at the levels the engineer specifies. Capping units finish the top. Because the face is the finished surface, we set out the first course precisely; everything above it follows.