A Study on Use of Natural Fiber for Improvement in Engineering Properties of Dense Graded Bituminous Mixes with Coal Ash
Transp. in Dev. Econ.
A Study on Use of Natural Fiber for Improvement in Engineering Properties of Dense Graded Bituminous Mixes with Coal Ash
Saswat Biswapriya Dash 0 1 2
Mahabir Panda 0 1 2
0 Department of Civil Engineering, National Institute of Technology , Rourkela 769008, Odisha , India
1 Mahabir Panda
2 & Saswat Biswapriya Dash
Coal-based thermal power plants have been a major source of power generation in India. The prime waste products of a coal based thermal power plant are fly ash and bottom ash. Heavy dumping of these waste products causes fatal environment pollution to air, water, and land, besides impairing human health. This research work is done to explore the optimum use of ash, namely bottom ash (as part of fine aggregate) and fly ash (as mineral filler) along with natural fiber (such as sisal fiber) used to improvise the engineering properties of bituminous paving mixes. In the present laboratory study, dense graded bituminous mix specimens were prepared using natural aggregates as coarse aggregates, bottom ash as fine aggregates, fly ash as filler and sisal fiber as additive. To strengthen the mix, slow setting emulsion (SS1) coated sisal fiber was added in varying percentages such as 0, 0.25, 0.5, 0.75, and 1 % by weight of the mix, with variations of sisal fiber length such as 0, 5, 10, 15 and 20 mm. The most suitable composition (such as optimum bitumen content and optimum fiber content including the optimum length of fiber in the bituminous mix) was selected based on the results of Marshall tests. Further, for justifying the performances of the bituminous paving mix thus developed, tests for indirect tensile strength and moisture susceptibility in the form of tensile strength ratio and retained stability of bituminous mixes were conducted.
Fly ash; Bottom ash; Sisal fiber; Dense graded bituminous mix (DBM); Marshall test; Indirect tensile strength
Introduction
Aggregates in coarse, fine and filler fractions are the main
constituents of the bituminous paving mixes. In many
construction sites, aggregates in different size fractions are not
easily available, necessitating their procurement from long
distances thereby causing exorbitant increase in cost of
construction. On the other hand, 70 % of the total power
generation in India is due to coal based thermal power plant,
that also contribute about 112 million tons of coal ash as
byproduct waste in every year from 120 coal based thermal
power plants (2010–11 data) [
5
]. Such a huge quantity of this
type of waste material does pose challenging problems, in
the form of land usage, health hazards and environmental
dangers. Hence to suppress the said problems related to these
materials, a good number of studies have been attempted to
utilize them in a productive way which will satisfy the needs
of the society. This particular work is an attempt to utilize
these waste materials to some extent by replacing the filler
and some fractions of fine aggregates in bituminous paving
mixes. In order to enhance the properties of the paving
mixes, their modification with different types of fibers is also
done. In order to offset the possible drawbacks of using the
coal ashes, unlike conventional fibers, naturally, locally and
abundantly available sisal fiber has been tried in possible
development of sustainable bituminous paving mixes to
improve the pavement performance. Sisal fiber is obtained
from a plant with a botanical name Agave sisalana [12].
Ali et al. observed through an experimental study on the
outcome of fly ash on the mechanical properties of
bituminous mixtures, that fly ash as mineral filler can be
used to increase resilient modulus characteristics and
stripping resistance [
1
]. As per Churchill and Amirkhanian,
partial substitution of fine aggregates by coal ash had a
moderate detrimental effect on short-term tensile strengths.
Results of a limited field study showed that 3 months after
placement, metal concentrations in soils were not
substantially altered [
2
]. Colonna et al. studied the feasibility
of bottom ash for HMA (Hot Mix Asphalt) mix used in the
intermediate courses of flexible pavements. Their results
show that the mixtures perform better when 15 % of
bottom ash was added to the mixture in replacement of
correspond amount of sand [
3
]. Kar studied the effect of sisal
fiber on SMA (Stone Matrix Asphalt) and bituminous
concrete (BC) mixtures and he concluded that the optimum
bitumen contents for BC and SMA mixes were 5 % and
5.2 % respectively whereas optimum fiber content for each
mix was 0.3 % [
13
]. From the scanty literature available, it
is observed that there is no study on utilization of bottom
ash and fly ash together in the same bituminous mix and the
use of a natural fiber in SMA and BC mixes. Hence, this
was the main motivation of the present research work.
In the present study, dense graded bituminous mix
specimens were prepared using natural aggregate as coarse
aggregates, bottom ash as part (...truncated)