Page 1 of 5
European Journal of Business &
Social Sciences
Available at https://ejbss.org/
ISSN: 2235-767X
Volume 07 Issue 05
May 2019
Available online:https://ejbss.org/ P a g e | 871
Recycled concrete aggregate/municipal glass blends as a
Low-carbon resource material for footpaths
V. SELVANATHAN
DEPARTMENT OF CIVIL ENGINEERING
PRIST (Deemed to be University)THANJAVUR.
ABSTRACT
This paper investigates the feasibility of using recycled concrete aggregate (RCA) as a
replacement to the natural aggregates (NAs) in hot mix asphalt (HMA). RCA was collected
from two different sources (new concrete cubes used for quality control testing during
construction, and old demolished building) to investigate the impact of material degeneration
on the engineering properties of the mix. Basic engineering properties were determined for
both RCA and bitumen for the preparation of HMA mixes. Different mix designs were
conducted using the conventional Marshall method with 100% RCA or substituting the
coarse natural aggregates (retained on the US Standard Sieve No. 4) by RCA. Performance of
the investigated mixes in terms of stability, flow, loss in abrasion, loss of stability, and
indirect tensile strength was evaluated.
INTRODUCTION
The economic and population growth
along with the expansion of urban areas
stipulates the construction of a larger road
networks. This led to a significant increase
in the use of natural aggregates, which has
a direct impact on the environment and the
consumption of energy and economy as
well as depletion of the natural resources
more quickly. To solve these
environmental problems, search for
alternatives to the natural aggregates for
use in road construction is going on. Of
these alternatives are construction and
demolition (C&D) waste materials, which
reduce carbon emissions, save landfill
areas, and reduce the construction cost.
Most of the generated waste in the world is
due to the construction activities mainly
from C&D materials, which pollute the
environment and increase global warming
[1, 2]. The scarcity in natural resources
and the increasing cost of waste disposal to
landfills highlight the importance of
reusing C&D waste materials as a good
alternative to natural aggregates in
Page 2 of 5
European Journal of Business &
Social Sciences
Available at https://ejbss.org/
ISSN: 2235-767X
Volume 07 Issue 05
May 2019
Available online:https://ejbss.org/ P a g e | 872
pavement construction [3, 4]. In 2015, the
Egyptian Environmental Affairs Agency
(EEAA) estimated that about 4 million
tons of C&D waste materials (about 4% of
the total generated solid waste) are
dumped [5]. In Cairo alone, the C&D
waste is about 3290 ton/day. Most of this
waste is generated from the demolition of
high-rise buildings representing about 39%
of the total construction waste. The two
main components of C&D waste materials
are recycled concrete aggregate (RCA) and
recycled clay masonry bricks (RCM). El- Badawy et al. [6] concluded that the C&D
waste materials have geotechnical
engineering properties equivalent or
superior to that of typical quarry granular
materials. However, there are some
barriers that hinder the use of these
materials such as lack of trained
technicians, specifications and experience.
Many research studies [2, 7–13] were
conducted to evaluate the general
engineering properties and performance of
the RCA as unbound granular material in
pavement construction. They concluded
the validity of the RCA as unbound
granular material for base/subbase
construction.
However, few studies were conducted on
the use of RCA in hot mix asphalt (HMA).
De Brito and Saikia [14] concluded that
the crushing characteristics of RCA are
similar to conventional crushed rock, and
are not significantly affected by the
strength of the original concrete. By
contrast, Hiller et al. [15] found that the
RCA strength depends on the original
concrete mixture proportions and crushing
operations. The American Concrete
Pavement Association [16] described the
RCA particles as angular with rough
surfaces. Parekh and Modhera [17] noted
that a decrease in the specific gravity of
RCA,increased the water absorption due to
the great amount of the attached cement
paste, which absorbed greater quantities of
water than natural aggregates. They also
observed that RCA had higher degradation
in terms of Los Angeles Abrasion (LAA)
compared to natural aggregate (NA). Al- Bayati et al. [18] used 0, 15, 30, and 60%
coarse RCA in HMA superpave mix
design and found that the addition of
coarse RCA with different proportions is
very successful for both untreated and
treated conditions and achieved all Ontario
Ministry of Transportation (MTO)
requirements for HMA.
RESULTS AND DISCUSSION
Table 2 summarizes the general
engineering properties of the investigated
Page 3 of 5
European Journal of Business &
Social Sciences
Available at https://ejbss.org/
ISSN: 2235-767X
Volume 07 Issue 05
May 2019
Available online:https://ejbss.org/ P a g e | 873
RCA from the two sources. It can be seen
from the table that the new RCA showed
lower bulk specific gravity, higher
absorption, higher liquid limit with no
plasticity, higher pH, and lower LAA in
comparison with those of the old RCA.
However, the loss in LAA was within the
specification limits of the ECP for both
sources [35]. Percentage of water
absorption for the two sources whether for
coarse or fine aggregates surpassed the
requirements specified by ECP.
To minimize the percentage of absorption,
in particular, the fine fractions, each
fraction was separated for determining
absorption as presented in Table 3. Results
showed that the percentage of the
absorption for the fractions retained on
sieve #3/8 was within the ECP limits of a
maximum value of 5% for both RCA
sources, while other fractions passing the
#3/8 sieve were higher than that limit. This
means that the fine RCA is the reason for
the increase in absorption; therefore, the
fine fractions were excluded and replaced
by fine NA in the preparation of HMA
mixtures to have lower binder content and
consequently an economic mix.
Table 4 presents a summary of the routine
testing results performed on virgin asphalt.
It can be observed from the table that the
properties of the virgin asphalt comply
with the Egyptian standards [35].
For Marshall design, the maximum
theoretical specific gravity, Gmm, of the
loose mix was determined by Rice test in
accordance with the AASHTO T 209 [49].
Eighteen specimens in total at different
binder contents ranging from 4.5 to 7.0%
were prepared and tested in Marshall
equipment for wearing surface mix design.
The OAC to satisfy all the ECP
requirements was then determined. Table 5
gives a summary of the results obtained by
Marshall test for all mixtures.
It is evident from Table 5 that the 100%
new RCA exhibited the highest stability
with higher content of OAC, despite the
lowest density and the highest voids filled
with asphalt (VFA) in comparison with
those of other mixes at the same level of
air voids (AV) of 4%. The reason for the
higher value of VFA was due to the higher
absorption of the 100% new RCA
compared with other mixes, yielding lower
content of effective asphalt binder as
agreed with Motter et al. [24], and hence
lower voids in mineral aggregate (VMA).
Replacement the fine RCA in the 100%
new RCA mix by fine NA significantly
reduced the bitumen absorption by 6.25%,
but with 25% reduction in the stability. By
