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www.concreteinternational.com | Ci | MARCH 2015 53
Novel Ultra-High-
Performance Glass
Concrete
New material used to fabricate pedestrian bridges on the University of
Sherbrooke campus
by Arezki Tagnit-Hamou, Nancy Soliman, Ahmed F. Omran, Mohammed T. Mousa, Nicolas Gauvreau, and
MFrancine Provencher
Ultra-high-performance concrete (UHPC) is dened
worldwide as concrete with superior mechanical,
ductility, and durability properties. A typical UHPC is
composed of cement, quartz powder (QP), silica fume (SF),
quartz sand (QS), and steel bers.1 UHPC achieves compressive
strengths of at least 150 MPa (22,000 psi), exural strengths
up to 15 MPa (2200 psi), elastic moduli of up to 45 GPa
(6500 ksi), and minimal long-term creep or shrinkage.2 It can
also resist freezing-and-thawing cycles and scaling conditions
without visible damage, and it is nearly impermeable to
chloride ions.3 UHPC is thus a promising material for special
prestressed and precast concrete elements (decks and
abutments for lightweight bridges and marine platforms;
urban furniture; and precast walls), concrete repair, and
architectural façade elements.4
Although UHPC is relatively expensive to produce, it
presents some economic advantages because its enhanced
properties allow:
•Reduction or elimination of passive reinforcement in
structural elements;
•Reductions in the thickness and self-weight of concrete
elements; and
•Increases in service life accompanied with reductions in
maintenance costs.5
UHPC is designed with a very high cement content
ranging between 800 and 1000 kg/m3 (1350 and 1690 lb/yd3),
which leads to high production costs, consumes natural
sources, and increases CO2 emissions. These factors and
others such as a relatively high SF content (25 to 35% by
weight of cement) are considered impediments to UHPC use
in the concrete market.
Ultra-high-performance glass concrete (UHPGC) is a new
type of UHPC that constitutes a breakthrough in sustainable
concrete technology,6 as it comprises granulated post-consumer
glass with a specic particle-size distribution (PSD) developed
using glass sand, high amounts of glass powder, and moderate
contents of ne glass powder. UHPGC is a ber-reinforced
concrete characterized by a very dense microstructure, which
enhances durability via a discontinuous pore structure. While
UHPGC can be designed with less cement, SF, QP, and QS
than typical UHPC, it still contains bers and a high-range
water-reducing admixture (HRWRA).
UHPGC can be produced with low water binder ratio
(w/b), yet because the glass particles have zero absorption, its
rheological properties allow it to be practically self-placing.
Depending on UHPGC composition and curing temperature,
the concrete’s compressive strength can range from 130 to
260 MPa (20,000 to 40,000 psi), while exural strength can
exceed 15 MPa (2200 psi), tensile strength can exceed 10 MPa
(1500 psi), and elastic modulus can exceed 45 GPa (6500 ksi).
UHPGC is characterized by excellent durability. Due to its
high packing density and lack of interconnected pores,
UHPGC has negligible chloride-ion penetration, low mechanical
abrasion, and very high freezing-and-thawing resistance.
Pedestrian Bridges
Developing UHPGC was one of the main goals of the
University of Sherbrooke’s industrial chair on the valorization
of waste glass in materials. After a major research program,
this newly developed concrete was used to fabricate new
footbridges to replace deteriorated wooden structures on the
University of Sherbrooke campus, Sherbrooke, QC, Canada.
The technology enabled the designer to create thin sections
that are light, graceful, and innovative in geometry and form
at a relatively low cost. In addition, the structure is expected
to be durable with high abrasion and impact resistance.
54 MARCH 2015 | Ci | www.concreteinternational.com
Materials
As with any concrete or mortar,
UHPC rheology is strongly affected by
cement neness as well as the two most
reactive components in portland
cement—C3A and C3S. The cement
characteristics are even more critical in
the case of UHPGC, as the very low w/b
results in close packing of the cement
particles. It is particularly important to
select cement with the lowest contents
of C3A and C3S. The cement selected for
the UHPGC footbridges was formulated
with a low C3A amount to provide high
sulfate resistance. The cement properties
included: Bogue composition of 50%
C3S, 25% C2S, 14% C3A, and 11%
C4AF; specic gravity of 3.21; Blaine
neness of 370 m2/kg; and D50 of 11 µm.
Other materials used in the UHPGC
mixture included:
•SF compliant with CAN/CSA-
A3000-13 “Cementitious materials
compendium” specications with
silica content of 99.8%, specic
gravity of 2.20, D50 of 0.15 µm, and
specic surface area of 20,000 m2/kg;
•QS with silica content of 99.8%,
specic gravity of 2.70, D50 of 250 µm,
and maximum particle size of 600 µm;
•Glass powder (GP) with silica
content of 73%, specic gravity of
2.60, maximum particle size of
100 µm, and Na20 content of 13%;
•Polycarboxylate-based HRWRA,
marketed as ViscoCrete-6100 (Sika);
and
•Polyvinyl alcohol (PVA) bers with
13 mm (0.5 in.) length and 0.2 mm
(0.008 in.) diameter.
Concrete mixture
The mixture design was developed in
three steps. In the rst step, the packing
density of the granular composition
(QS, GP, cement, and SF) was optimized
to 0.78% using the compressible
packing model.7 The resulting mixture
comprised 410 kg/m3 (690 lb/yd3) of GP.
In the second step, the optimum
HRWRA dosage was determined for a
range of w/b values, yielding the
rheological characteristics needed to
obtain a self-consolidating matrix as
well as adequate strength. In the third
step, the ber content was optimized
as needed to improve the UHPGC
ductility without signicantly altering
the rheological properties of the
fresh mixture.
Table 1 provides the compositions for
the UHPGC mixtures with w/b of 0.24
used in this project.
Design
The footbridges were designed to
meet the university’s architectural and
structural requirements for pedestrian
use as well as to be in compliance with
the university’s regulation on sustainable
development. Because the mechanical
properties of the UHPGC allowed the
spans to be constructed with relatively
small cross sections, each bridge had a
total weight of around 4000 kg (8800 lb).
The structural system consisted of an
arch slab 4910 mm (193 in.) in length,
2500 mm (98 in.) in width, and 75 mm
(3 in.) in thickness supported by
longitudinal ribs of variable height and a
constant width of 130 mm (5 in.). Using
the mechanical properties determined
during the testing program, the section
was designed to meet strength and
serviceability limits as per the university’s
requirements. The arch slab was
reinforced with welded wire reinforce-
ment (M10 at 300 mm [12 in.] in both
directions) placed at the midheight of
the slab. Each rib was reinforced with a
single M20 reinforcing bar located near
the bottom of the rib. Figure 1(a) shows
the footbridge reinforcement arrange-
ment and Fig. 1(b) provides the concrete
dimensions. One footbridge was
instrumented with thermocouples and
vibrating wire strain gauges so that
temperature and deformation could be
monitored over time.
Formwork
The mold for the bridges was built at
the Bétons Génial, Inc., plant and then
transported to the university’s integrated
laboratory for innovative and sustainable
materials and structural valorization
research. Bétons Génial, Inc., designed
and built a reusable wooden mold
integrating a urethane-rubber facing
with specic shore hardness. The facing
Table 1:
UHPGC mixture design
Materials kg/m3
Type HS cement 555
Silica fume (SF) 205
Glass powder (GP) 410
Water 226
Syntactic fiber 32.5
Quartz sand (QS) 888
HRWRA (solid content) 17
Note: 1 kg/m3 = 1.69 lb/yd3
was designed to produce a textured,
non-slip walking surface on the decks
and very smooth, joint-free surfaces on
other surfaces of the bridges (Fig. 2).
Although UHPGC shrinkage is very
low, the liner material was selected to
accommodate concrete shrinkage and
minimize the risk of creating micro-
cracks during concrete curing. The mold
was designed so that the bridge could be
cast upside down, allowing the relatively
complex shape to be formed with the
integral non-slip areas on the deck.
Production
The UHPGC was produced at the
University of Sherbrooke laboratory
using a pilot-scale automatic concrete
plant with a paddle-type stationary pan
mixer with a 500 L (18 ft3) capacity. To
achieve a homogeneous mixture and
avoid particle agglomeration, all powder
materials were dry mixed for 10 minutes
before the water and HRWRA additions.
About half of the HRWRA was diluted
in half of the mixing water, and this
was gradually added over the next 3 to
5 minutes of mixing time. The remaining
water and HRWRA as well as the bers
were then added over the following 3 to
5 minutes of mixing time. The total
mixing time was 20 minutes.
Four batches of concrete were
produced for a total of 2.0 m3 (3 yd3) for
each footbridge. Concrete production
and placement took 2 hours. Once the
four batches had been loaded into the
hopper, the UHPGC’s uidity and
self-placing properties allowed for
placing the concrete into the mold in
fewer than 12 minutes without external
www.concreteinternational.com | Ci | MARCH 2015 55
Fig. 1: Bridge schematic: (a) longitudinal section at centerline; and (b) bottom view showing
concrete dimensions. Dimensions are in mm (nearest in.)
(a)
(b)
75
(3)
75
(3)
75
(3)
75
(3)
75
(2.95)
119
(5)
272
(11)
1508
(59)
496
(20)
130
(5)
300
(12)
100
(4)
2500
(99)
455
(18)
455
(18)
455
(18)
455
(18)
150
(6)
328
(13)
4910
(193)
4910
(193)
280×1138
(11x45)
EPS foam block;
216 (9) depth
150×1578
(6x62)
EPS foam block;
depth varies
Bottom of flange
Bottom of ribs
Bearing surface
Fig. 2: The footbridge
mold was designed to
provide formed
surfaces on all
exposed faces: (a) a
wooden insert was
fabricated in the shape
of the deck wearing
surface and curbs; and
(b) the insert was used
as the master to cast
the urethane rubber
liner used for
production of the
footbridges
(a)
(b)
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56 MARCH 2015 | Ci | www.concreteinternational.com
vibration. While the UHPGC couldn’t be described as
self-consolidating, it owed extremely well. Only 1 minute of
internal vibration was required to ensure good compaction.
After casting, exposed concrete was covered with plastic
sheeting until the mold was removed. For each bridge, the
mold was removed 24 hours after placement. First, an
overhead crane was used to open the mold by separating its
two parts with straps and anchors (Fig. 3(a)). The bridge was
then lifted and rotated (Fig. 3(b)). After form removal,
plastic sheeting was placed over each footbridge to allow
continued curing.
The UHPGC’s fresh and rheological properties were
measured after mixing. Specimens needed for compressive,
tensile, and exural strength tests as well as modulus of
elasticity, resistance to mechanical abrasion, scaling, freezing-
Fig. 3: The footbridge was cast upside down. The mold base held the
urethane rubber liner shown in Fig. 2, and the mold was closed with
a separate wooden insert that formed the curved and ribbed bottom
surfaces of the footbridge: (a) the insert is removed from the mold
base, exposing the bottom concrete surfaces and the expanded
polystyrene blocks indicated in Fig. 1; and (b) the footbridge was
pulled from the mold using straps and anchors, and a steel frame
was attached in preparation for flipping the completed structure
(a)
(b)
and-thawing resistance, chloride-ion penetration, and resistivity
tests were then fabricated. Tests were performed according to
ASTM International standards. The samples were stored at
23°C (73°F) and 100% relative humidity (RH) for 24 hours
before mold removal, after which they were stored in a fog
room at 23°C (73°F) and 100% RH until testing.
Installation
Before the bridges were transported to their installation
sites, wooden and steel railings were attached (Fig. 4). A
simple atbed truck was used for transportation to the site
(Fig. 5), and a truck-mounted crane and straps were used to
lift and install the bridges on conventional concrete abutments
with neoprene bearing pads. Lifting and placing took a little
less than an hour.
Concrete Performance
Fresh properties
Tests were performed to obtain basic fresh concrete
properties including slump ow (ASTM C1437, “Standard
Test Method for Flow of Hydraulic Cement Mortar”), unit
weight, air content, and temperature (ASTM C185, “Standard
Test Method for Air Content of Hydraulic Cement Mortar”)—
values were 280 mm (11 in.) without tamping, 2231 kg/m3
(140 lb/ft3), 3.5%, and 22°C (72°F), respectively.
To examine the concrete’s ability for self-placement
without consolidation or segregation issues, various tests
normally carried out for self-consolidating concrete were
performed. The slump-ow diameter with the Abrams cone
(ASTM C143/C143M, “Standard Test Method for Slump
of Hydraulic-Cement Concrete”) was 780 mm (31 in.).
The time to reach a 500 mm (20 in.) spread diameter
(T500) was 6.8 seconds, which explains the relatively high
viscosity. The visual stability index (VSI) was 0, which
means no evidence of segregation.
To ensure the concrete ows adequately around the
reinforcement bars, the difference between the slump-ow
diameter and the J-Ring spread diameter should not exceed
Fig. 4: As final preparation before shipping to the jobsite, wooden
and steel railings were attached to the UHPGC curbs
www.concreteinternational.com | Ci | MARCH 2015 57
50 mm (2 in.) according to the German
SCC guideline8 or 10 mm (0.4 in.)
according to EFNARC.9 This value was
only 5 mm (0.2 in.) for the UHPGC,
indicating excellent passing ability. The
blockage ratio for the J-Ring test was
0.83. The self-leveling index for the
L-Box test with two steel rods was 1.0
(the limit accepted under the EFNARC
2002 guideline9 is between 0.80 and
1.0). The time for the leading edge of
the concrete to reach the end of the
600 mm (24 in.) long horizontal section
was 9.8 seconds. This mixture’s
enhanced fresh properties derive from
the large incorporation of glass powder
with zero absorption.
Mechanical properties
Compressive-strength tests were
carried out according to ASTM C39/
C39M, “Standard Test Method for
Compressive Strength of Cylindrical
Concrete Specimens,” on 100 x 200 mm
(4 x 8 in.) cylindrical specimens at
1, 7, 28, and 91 days after normal
curing. The 28- and 91-day compressive
strengths of this UHPGC were 96 and
127 MPa (14,000 and 18,500 psi),
respectively. The increase in compressive
strength of about 33% from 28 days to
91 days indicates the glass powder’s
pozzolanic reactivity.
Other test conducted at 28 and 91 days
included: indirect splitting tensile
strength according to ASTM C496/
C496M, “Standard Test Method for
Splitting Tensile Strength of Cylindrical
Concrete Specimens,” on 100 x 200 mm
(4 x 8 in.) cylindrical specimens;
exural strength according to ASTM
C78/C78M, “Standard Test Method for
Flexural Strength of Concrete (Using
Simple Beam with Third-Point Loading),”
on 100 x 100 x 400 mm (4 x 4 x 16 in.)
prisms; and modulus of elasticity
according to ASTM C469/C469M,
“Standard Test Method for Static
Modulus of Elasticity and Poisson’s
Ratio of Concrete in Compression,” on
100 x 200 mm (4 x 8 in.) cylinders.
Table 2 lists the concrete’s mechanical
properties.
Durability properties
Concrete abrasion was measured
according to ASTM C944/C944M,
Table 2:
Mechanical properties of UHPGC
Properties
Concrete age, days
1 7 28 91
Compressive strength, MPa 12 52 96 127
Splitting tensile strength, MPa — — 10 11
Flexure strength, MPa — — 10 12
Modulus of elasticity, GPa — — 41 45
Notes: 1 MPa = 145 psi; 1 GPa = 145 ksi
“Standard Test Method for Abrasion
Resistance of Concrete or Mortar
Surfaces by the Rotating-Cutter
Method.” The average value of the
relative volume loss index was 1.35 mm
(0.05 in.). For a typical UHPC, the
relative volume loss index ranges from
1.1 to 1.7 mm (0.04 to 0.07 in.),10 which
itself is small relative to that for HPC
(2.8 mm [0.11 in.]) and normal concrete
(4.0 mm [0.16 in.]).3
Scaling resistance was measured
according to ASTM C672/C672M,
“Standard Test Method for Scaling
Resistance of Concrete Surfaces
Exposed to Deicing Chemicals.” After
50 freezing-and-thawing cycles, the
scaled mass was 12 g/m2 (0.04 oz/ft2).
The scaled mass reported for UHPC in the
literature, varies from about 8 to 60 g/m2
(0.20 oz/ft2) for samples subjected to
Fig. 5: The completed footbridges were transported on a flatbed truck and installed with a truck-mounted crane
58 MARCH 2015 | Ci | www.concreteinternational.com
Fig. 6: Variations of deformation and temperature with time obtained from instrumented
bridge (Note: °F = 1.8 x °C + 32°)
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
60
-1400
-1200
-1000
-800
-600
-400
-200
0
200
400
600
800
1000
1200
1400
10 20 40 50 70
Deformation, μm/m
Temperature, °C
Time, days
Total deformation
Temperature
at centerline of deck
Temperature at edge beam
Isothermal deformation:
Total deformation minus
thermal expansion
of concrete
030 60
28 to 50 freezing-and-thawing cycles.11
Resistance to chloride-ion penetration
was evaluated per ASTM C1202,
“Standard Test Method for Electrical
Indication of Concretes Ability to
Resist Chloride Ion Penetration.” The
28- and 91-day specimens exhibited
values below 10 coulombs, indicating
“negligible” chloride-ion permeability.
Resistance to freezing-and-thawing
was measured according to ASTM
C666/C666M, “Standard Test Method
for Resistance of Concrete to Rapid
Freezing and Thawing.” Relative
dynamic modulus was 100% after
700 freezing-and-thawing cycles.
The resistivity test was carried out
on 100 x 200 mm (4 x 8 in.) cylindrical
sample after 91 days of curing. An
extremely high value of 3466 kΩ•cm
was obtained. For comparison, the
resistivity is 1130 kΩ•cm for traditional
UHPC without bers, 96 kΩ•cm for HPC,
and 16 kΩ•cm for normal concrete.3
Bridge instrumentation
The temperature changes in one footbridge were moni-
tored with two thermocouples: one inserted in the center of
the deck and another in the center of the supporting (edge)
beam. Figure 6 provides the results from the two thermo-
couples. The temperature reached approximately 53°C
(127°F) in the rst days after casting, followed by a gradual
drop to laboratory temperature. After curing at laboratory
temperature (around 23°C [73°F]) for 28 days, the footbridges
were transferred to the eld sites, where the temperature
dropped below zero, as shown by the sudden drop in the
temperature curve. Some nights, the temperature fell to
–30°C (–22°F).
A vibrating wire gauge was inserted at the center of the
instrumented bridge deck to measure deformation due to
shrinkage (Fig. 6). A strain of about 430 µm/m was measured
at the end of laboratory curing, followed by a sudden increase
in the deformation at the eld site due to the temperature
changes and removal of the plastic sheeting (the strains
resulted from temperature change and additional drying
shrinkage). The total strain was as much as 1200 µm/m on
some days. After deducting thermal expansion, the isothermal
strain was about 800 µm/m.
Summary
A new type of UHPC has been developed using recycled
glass, creating UHPGC. The new material exhibited
excellent workability and rheological properties due to
the zero absorption of the glass particles and optimized
packing density for the entire material matrix. The
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www.concreteinternational.com | Ci | MARCH 2015 59
Arezki Tagnit-Hamou, FACI, is a Professor
in the Civil Engineering Department at the
Université de Sherbrooke, QC, Canada.
He is also the Head of the cement and
concrete group and industrial chair holder
on valorization of glass in materials. He is
a member of ACI Committees 130,
Sustainability of Concrete, and 555,
Concrete with Recycled Materials.
ACI and CRIB member Nancy Soliman is
a PhD candidate at the Department of
Civil Engineering, Université de Sher-
brooke. Her research interests include
development of NDT, ultra-high-perfor-
mance concrete, microstructure of
cement and concrete, and sustainable
development.
Ahmed F. Omran is a Postdoctoral Fellow
at the Department of Civil Engineering,
Université de Sherbrooke, and Assistant
Professor at University of Minuya, Menua,
Egypt. He received his BS and MS in civil
engineering from the University of Minuya,
and his PhD degree from Université de
Sherbrooke. He is a member of RILEM
Technical Committee 233-FPC.
ACI member Mohammed T. Mousa is a
PhD student in the Department of Civil
Engineering, Université de Sherbrooke,
Sherbrooke QC, Canada, and a civil
engineer at Helwan University, Cairo,
Egypt. He received his BSc in civil
engineering from Benha University, and
his MSc and PhD in civil engineering from
Helwan University.
Nicolas Gauvreau, is the Co-Founder,
Vice President, and Technical Director of
Bétons Génial, Inc., Saint Jean-sur-Richelieu,
QC, Canada. He has more than 20 years
of experience in prefabricated concrete
and molds. His company specializes in
unique and innovative manufacturing
processes.
MFrancine Provencher is an architect
member of L’Ordre des architectes du
Québec (OAQ) since 1984 and has been
credentialed as a LEED AP since 2004
with BD+C speciality. She is Director of
Planning and Sustainability Department at
the Building Services of Université de
Sherbrooke since 1993.
mechanical properties were found to be excellent and
comparable to conventional UHPC.
The construction of two UHPGC footbridges at the
University of Sherbrooke shows the potential for the material
to be used in future projects. UHPGC will produce highly
energy efcient, environmentally friendly, affordable, and
resilient structures.
Acknowledgments
This research was funded by the SAQ Industrial Chair on Valorization of
Glass in Materials and the authors gratefully acknowledge this support.
The authors would also like to acknowledge the support of the University
of Sherbrooke in conducting this project.
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Note: Additional information on the ASTM and CSA standards
discussed in this article can be found at www.astm.org and
www.csagroup.org, respectively.
Selected for reader interest by the editors.
