The Civil Engineering Contractor June 2018 | Page 21

TECHNOLOGY
(2017) Infrastructure Report Card (IRC)
for South Africa.
The report notes that in the global
economy, the state of a country’s
infrastructure capability provides one
of the key indicators of its future
prosperity. It is this which can either
advance or constrain its engagement
with the global economy.
In the report, Saice awarded South
Africa’s infrastructure a lowly
grade of D+. It is based on a US
infrastructure evaluation system that
grades local infrastructure into five
categories: A (world class), B (fit
for the future), C (satisfactory for
now), D (at risk), and E (unfit for
purpose). This simply confirms that
much of Africa’s and South Africa’s
infrastructure is in poor shape and
getting worse — largely due to the
extremities of climate experienced,
especially during the rainy season.
Johannesburg’s roads are just one
example. According to the most
recent assessment released in 2017
by the Johannesburg Roads Agency,
the city’s roads network is in ‘very
bad’ condition. Compared to 2013
results, the study states that the ratio
of ‘very good’ and ‘good’ surfaced
roads worsened from 52% to 45%.
The ratio of roads in ‘poor’ and ‘very
poor’ condition increased from 27%
to 32%. This reflects an overall 25%
increase in deterioration of the road
network condition.
Johannesburg’s road network is at
present faced with a R7.1-billion
backlog. Much of this cost could have
been avoided had new, technologically
improved waterproofing techniques
been available when the roads were
originally built. The same applies for
South Africa’s dams, bridges, airports,
railway lines, and water reticulation
network.
Deteriorating water supply is another
impact of worsening infrastructure,
again largely due to inadequate
waterproofing. This relies on well-
maintained pipelines to ensure a
constant and safe supply of water to
every South African, but corrosion
of an ageing pipeline infrastructure is
Poor shape and
getting worse
Waterproof membranes (geosynthetics) reduce maintenance costs of critical
bridge infrastructure.
costing businesses and municipalities
hundreds of thousands of rands a year.
New technologies
for the future
The problem with much of South
African infrastructure is that it has
outlived its intended service life. A
failure of traditional waterproofing
coatings has led to a material
corrosion of structural elements by
water, leading to crumbling concrete
and corroded rebar.
Saice’s 2017 IRC noted that a sizeable
proportion of the national road
network is older than the 20-year
theoretical design life. According
to Sanral, due to cost factors, the
waterproofing membrane on South
Africa’s roads is between 10 and
40mm thick, compared to an average
of 100mm in Europe and the US.
Good quality, natural gravel materials
were substituted to counter the high
import cost of bitumen. While this
substitution managed to reduce the
initial road construction outlay by
30–50%, the thinner waterproofing
layer has increased the need for
preventative maintenance when the
layer cracks and water ingress occurs.
However, bituminous road binders,
emulsions, primes, pre-coats, and
modified binders to serve the road
construction, maintenance, and
waterproofing industries, have been
locally manufactured in South Africa
since 2015 by SprayPave.
This company’s bitumen reactor is
the first of its kind in Africa and
enables it to locally produce the
harder/more scarce grades of bitumen
that previously had to be imported.
Its bitumen reactor produces these
grades from more readily available
feedstock, and can also re-engineer
inferior, poorer-performing products
to meet higher specifications.
Total cost of waterproofing could
also be reduced by new spray-applied
waterproofing products that are
durable, fast curing, impervious to
water, able to bridge cracks, and
capable of lasting decades without
extensive maintenance.
Spray-applied waterproofing is
widely used in the US, now accounting
for over half the membranes applied
to bridges in some parts of the US due
to its enhanced durability, bonding to
concrete, and crack-bridging ability.
On bridges, if cracks form due to
deterioration of the deck or heavy
traffic, water may ge t into cracks and
the concrete matrix. Therefore, the
membrane must be pliable enough to
accommodate these cracks without
failing.
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