A 146m concrete block retaining (CRB) wall which reaches a maximum height of 8,5m, has been built for Amidad Trading using Aveng Manufacturing Infraset’s Ridgebloks® at new warehouse premises in Burgersfort, Mpumalanga.
A second wall, three-metres high and 55m long, was built on the same site with Aveng Manufacturing Infraset’s Terrace Blok® TB300 and TB490 retaining blocks.
Designed by TMV Consulting and built by Engineered Interlock Solutions, the walls were erected to protect embankments adjacent to the warehouse.
Brennan Small, Aveng Manufacturing Infraset: Landscape Products sales manager, comments that the walls were erected at steep 85º angles in order to free up as much space as possible for the construction of the warehouse.
“The site is situated on a fairly steep slope and a level platform was created by excavating into the slope.
“Further cutting into the embankment was undertaken to create space for the geosynthetic reinforcement of the walls and the excavated soil was stockpiled for re-use as backfill material. There were also outcrops of rock in some sections of the embankment and compressors were used to break it up,” said Small.
Actual construction began by laying base blocks at 85º on top of the foundations which were 100% level. This created a level base and the desired starting point five degrees off the vertical.
Small said that during construction, high-tenacity, polyester-coated woven reinforcing grid was installed at every third block and that the tieback length of the grid was equivalent to 80% of wall heights.
Moreover, soil compaction levels one metre in from the external wall face was carefully monitored during construction to ensure that the blocks won’t be pushed forward during the lifespan of the walls, as this would steepen the angle of the wall faces.
Small advises that a good drainage system is essential to the proper functioning of a retaining wall.
“Drainage of the Burgersfort walls was achieved through the installation of perforated pipes covered with 19mm stone and wrapped with non-woven polyester sheeting. A needle-punched geotextile fabric was laid against the back-face and drainage outlets were installed at three-metre intervals. Furthermore, 250 wick drains were installed against the back-face to collect any sub-surface water behind the reinforced backfilled sections.”
Small concluded by saying that the project complied with all SANS 207 requirements.