38
CONSTRUCTION WORLD
JUNE
2014
PROJECTS AND CONTRACTS
2014
The TB300® was used to construct
2 200 m² of open-face retaining
walls. In addition, 1 400 m² of
closed-face walling was erected
using
Aveng
Manufacturing
Infraset’s
Infrablok™ 350 retaining wall block. Begun in
July 2013, both types of terrace walling were
completed by the end of April 2014.
The Village is being developed by Central
Developments Property Group. Situated
on sloping ground, the site required exten-
sive terracing and embankment buttressing
to provide level building platforms for the
construction of houses, apartments and
communal buildings.
The retaining walls were designed and
built by Engineered Interlock Solutions (EIS)
in close collaboration with the main earth-
works contractors, Loneock, and consulting
engineers, Pro North Consultants, to ensure
that all statutory requirements were met.
EIS owner, Manie Troskie, says that the
property was terraced using a combination
of concrete block retaining (CRB) walls as
well as some conventional cast-in-situ
retaining walls.
“We proposed the use of CRB walling
wherever possible as this provided the client
with more options for less money. Moreover,
CRB walls offered faster construction times
and provided a softer, more aesthetically
pleasing look.
“Prior to our involvement, early designs
had specified conventional reinforced con-
crete walling on the perimeter of the property
and on some of the steeper embankments.
As an alternative we proposed the use of
CRB walls using geosynthetic reinforced soil
and Aveng Manufacturing Infraset’s multi-
blend Infrablok™ 350 in a split-face finish. On
embankments with more gradual gradients,
we advised using the new Terrace Blok® 300
in an open-face configuration.
“More than 10 open-face walls varying in
height between 2 m to 7,5 m were built at an
angle of 75˚ using seven Terrace Blok® 300s
per square metre. Even without plant growth
these walls look extremely attractive, the
split-faced blocks and the open-faced finish
creating an eye-catching rustic effect.
“These open-face walls were reinforced
with Kaytech’s Miragrid, a geosynthetic mate-
rial which is manufactured from high tenacity
polyester (PET) yarns. The tie-back lengths,
spacing and strength ratings of the Miragrid
varied according to the height of the walls,”
said Troskie.
Four closed-face walls were built with
Infrablok™ 350s, two on the perimeter
and two inside the property. CRB walling
was particularly well suited to the perim-
eter walling because the footing of in-situ
retaining walls would have extended beyond
the boundary and sewer line. The height of
the perimeter walls varied between 1,5 m
and 4,5 m and the inner walls varied between
2 m and 7,5 m. All four walls were built at a
near vertical angle of 85˚ using 18 blocks per
square metre.
Besides the Infrablok™ 350s, the perim-
eter walling was constructed with reinforced
concrete because the distance between the
rear of the CRBs and the cut face was only
500 mm which was deemed insufficient for
geosynthetic reinforcement only. Concrete
was poured into the CRB cavities and the
space between the blocks and the cut faces.
Reinforcing comprised Kaytech’s Micro-
>
Retirement village’s
RETAINING WALL
A new concrete retaining wall
block, Aveng Manufacturing
Infraset’s split-face Terrace
Blok® 300, has enjoyed a
spectacular launch at the
Olivedale Retirement Village,
currently under construction in
Olivedale, Johannesburg.
A section of the closed-face perimeter walling
built with Infrablok™ 350s.
grid 75/75 high-tenacity polymer-coated
polyester (PET) and Y16 steel which was laid
horizontally in the foundations and vertically
inside and behind the blocks. The concrete
was poured in layers, one block height at a
time, and the Microgrid material was inserted
between layers.
The largest inner closed-face wall
was also reinforced with Microgrid 75/75.
It was placed above every second layer of
Infrablok™ 350s and was tied back 5,5 m into
the earth embankment. This wall supports a
terrace upon which a multi-storey building
has been constructed 1,8 metres from the top
edge of the wall.
The smaller closed-face application
involved building a wall to secure a three
metre embankment. Two houses had already
been constructed above the embankment
and in this instance a concrete reinforced
retaining wall combined with a geosynthetic
reinforced CRB wall using Infrablok™ 350s
provided the best solution.
Troskie says that his company has stand-
ardised its CRB requirement on blocks manu-
factured by Aveng Manufacturing Infraset.
“Not only are the blocks manufactured to
the highest global standards, but I know the
blocks will always be properly cured. More-
over, we can always rely on Aveng Manufac-
turing Infraset to deliver on time, never late
and never early,” concludes Troskie.
1. Terrace Blok® 300 open-face walling meets
Infrablok™ 350 closed-face walling at
Olivedale Retirement Village.
2. Sections of Terrace Blok® 300 open-face
walling at Olivedale Retirement Village.
3. A 7,5 m section of closed-face walling
constructed with Infrablok™ 350 concrete
blocks.
4. Manie Troskie stands next to a curved
section of 7,5 m Infrablok™ 350 closed-face
walling. The wall supports a multi-storey
building which was constructed 1,8 metres
from the top edge of the wall.
