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Comité technique 307
case approach with proper investigations for making decisions
regarding the suitability of fly ash as a construction material.
Kikuchi and Mizutani proposed the use of granulated blast
furnace slag (GBFS) as an alternative construction material for
port structures because GBFS can reduce liquefaction potential
and earth pressure when used as a backfill material for quay
walls. The inherent ability of GBFS to solidify upon contact
with seawater was explored and methods were proposed for its
standardized application in the field. As GBFS solidification is a
lengthy process and often the solidification is not uniform,
Kikuchi and Mizutani proposed the use of powdered blast
furnace slag (PBFS) in conjunction with prior homogeneous
mixing treatment (PHMT) to accelerate the GBFS solidification
process. In their experimental investigation, Kikuchi and
Mizutani considered several issues, e.g., material separation
after construction due to water flow, solidification of GBFS
underground with flowing water, and the effect of the change in
pore fluid chemistry due to a change from sea to fresh water on
GBFS solidification, in determining the most appropriate
mixture of GBFS and PBFS for accelerating the GBFS
solidification. The authors found that PHMT treated GBFS-
PBFS mixture is effective in reducing the amount of material
separation in the GBFS-PBFS mixture and produced sufficient
unconfined compression strength after about 2 months of curing
in the seawater because of which it can be used to prevent
liquefaction.
Nawagamuwa et al. investigated the properties of waste
copper slag for use in vertical sand drains and sand piles as a
substitute for sand. Geotechnical properties such as particle size
distribution, hydraulic conductivity, shear strength, and stiffness
were studied for the sand-sized waste copper slag particles
mixed with poorly graded sand. It was observed that the particle
size distribution, shear strength and hydraulic conductivity were
not significantly affected due to the addition of the slag.
However, the stiffness of the slag-sand mixture increased
significantly. Based on the study, Nawagamuwa et al. concluded
that waste copper slag can be safely and effectively used as a
replacement for sand in vertical drains.
Vizcarra et al. (2013) investigated the applicability of
municipal solid waste (MSW) incineration ash mixed with non-
lateritic clay in pavement base layers. Chemical, physical,
index, and mechanical tests were performed on the ash-soil
mixture with 20% and 40% ash content, and the mechanistic-
empirical design (Figure 3) for a typical pavement structure
were carried out. The mechanical tests included modified
Proctor test, resilient modulus test, and permanent deformation
test. The addition of 20% fly ash to the non-lateritic clay soil
improved the mechanical behavior and reduced the expansion of
the clay. The fly ash mixed soil had a mechanical behavior
compatible with the requirements for a low traffic volume.
Edil also focused on pavement geotechnics and provided an
overview of different recycled waste products used in pavement
construction. He discussed about the rapid characterization of
industrial wastes like fly ash and bottom ash, and construction
and demolition wastes (CDW) like recycled asphalt pavement
and concrete aggregates with respect to their physical
characteristics, geomechanical behavior, durability, material
control, and environmental impact.
In another study related to pavements, Cameron et al.
proposed the use of recycled concrete aggregates (RCA)
blended with recycled clay masonry (RCM), obtained after
demolition, in unbound granular pavements. The CDW were
obtained from two local producers in South Australia, and
conventional classification tests for soils and aggregates, Los
Angeles abrasion test, Micro-Deval test, falling head
permeability test, drying shrinkage test, undrained triaxial and
repeated loading triaxial tests, and permanent strain rate
modeling were performed. The test results were compared with
the specifications from road authorities both within and outside
Australia, and the RCA products were classified as Class 1 or
base and the blended products as Class 2 or subbase materials.
Figure 3. Pavement structure adopted in mechanistic-empirical analysis
(Figure 1 of Vizcarra et al.).
Farias et al. also studied the feasibility of using CDW in
paving of a shopping-center site in Recife, Pernambuco, Brazil.
They performed a series of physical, chemical and mechanical
tests with mixtures of different proportions of CDW obtained
from the site and in situ excavated soil, and concluded that the
recycled residues of civil construction (RRCC) alone and RRCC
mixed with soil meet all the criteria of the local standard NBR
15.116:2004. Farias et al. (2013) also performed an economic
analysis of different construction alternatives with the RRCC,
which is described in section 3.5.
The study by Santos et al. also involves CDW. They
presented a laboratory-scale experimental investigation on the
performance of instrumented wrapped-faced retaining walls
constructed using recycled construction and demolition wastes
(RCDW) consisting of soil, bricks, and small particles of
concrete. CDW is abundantly available in Brazil and
approximately 70% by mass of municipal solid waste consist of
CDW. CDW was found to have excellent mechanical and
chemical properties for use as a back-fill material in
geosynthetics reinforced walls. Consequently, two 3.6-m high,
wrapped-faced retaining walls with facing batter angle of 13
were constructed at the University of Brasilia (UnB) Retaining
Walls Test Facility. One retaining wall was constructed with
geogrid and the other with geotextile with identical
reinforcement lengths and spacings of 2.52 m and 0.6 m,
respectively, using RCDW as the compacted backfill (Figure 4).
The walls were instrumented along their central sections to
measure strains, displacements, and earth pressures. The walls
performed well during and after construction with the maximum
horizontal displacement at the wall face being 150 mm. The
only downside was the creation of uneven surfaces near the face
due the presence of coarse particles. The use of a selected
RCDW near the face for better aesthetic appeal was
recommended.
Vaníček et al. presented an example of waste recycling in
which a new construction material consisting of brick, fiber and
concrete was used to reinforce dykes for flood protection and
erosion control.
Winter discussed the use of lightweight tire bails (Figure 5)
as a potential alternative for pavement foundation on soft soils.
Tire bales comprise of 100 to 115 tires of light-goods vehicles
and cars compressed into a lightweight block with a mass of
about 800 kg and density of approximately 0.5 Mg/m
3
. The
bales measure approximately 1.3 m
1.55 m
0.8 m and are
secured by five galvanized steel tie-wires running around the
length and depth of the bale. The key advantage of tire bales is
their modular nature which leads to potential savings in plant,
labor, and time. These bales have been used in pavement
constructions, slope protection, river bank erosion control, and
lightweight embankment constructions. Winter described the
different construction techniques and provided information
regarding the measurement of properties, engineering properties
