CONCRETO & Construções | Ed. 93 | Jan – Mar • 2019 | 59
u
Figure 2
Schematic of data acquisition from a sensor Bottom
DAQ
System
Wireless
Sensing
Unit
Wireless
Sensing
Unit
Front
CI
of major rehabilitation or outright re-
placement. Not surprisingly, nearly
half of our construction activity is cur-
rently geared towards the repair and
strengthening of our infrastructure,
and as the infrastructure ages fur-
ther, this will place further demands
on our already stretched infrastruc-
ture budget.
One additional setback facing
our already worn out infrastruc-
ture is Global Warming. With atmo-
spheric CO
2
levels expected to ap-
proach 1000 ppm from their current
level of 600 ppm and atmospheric
temperatures expected to rise by
as much as 5.5
o
C, deterioration in
our concrete structures is only ex-
pected to accelerate. Higher CO
2
levels will cause much greater car-
bonation and corrosion and higher
temperatures will lead to greater
thermal stresses and shrinkage in-
duced cracking. All in all, one can
expect greater instances of struc-
tural failure and increased mainte-
nance costs in the future.
2. STRUCTURAL HEALTH
MONITORING (SHM)
The Johnson Commission, which
investigated the Laval collapse,
strongly urged the government to
make bridge and overpass health
monitoring an absolute priority. Un-
fortunately, the current tools in our
arsenal for bridge inspections and
health monitoring remain antiquated
and unable to accurately predict the
true condition of the structure (Fig. 4).
In particular, they are unable to pre-
dict deterioration both in steel (aris-
ing from corrosion) and in concrete
(arising from chemical and physical
attack including freeze-thaw, scaling
u
Figure 3
Installing a sensor
on a bridge deck
u
Figure 4
Sensors for concrete structures
Crossbow tri-axial
Thermocouple
Wind monitor
Tilt-Beam sensor
Corrosion sensor
Fibre-Optic sensor
