Bituminous concrete, also referred to as asphaltic concrete, represents one of the most sophisticated and high-

concrete [1]. Traditional fillers like cement, limestone, and granite powder are not economically feasible or

widely available in Bangladesh.

In this context, a 50:50 combination of coal dust and coarse sand is considered a viable alternative, as both are

inexpensive and readily accessible. This study evaluates the effect of this blended filler on the behavior of

bituminous mixtures. It compares the performance of mixes containing a coal dust–coarse sand blend with that

of mixes using conventional filler types such as fine sand with stone dust in Bangladesh. The evaluation was

conducted using the Marshall mix design approach. The Marshall stability values for mixtures containing fine

sand with stone dust and the coal dust–coarse sand blend were measured at 2.15 kN, and 1.79 kN respectively,

all of which surpass the minimum threshold of stipulated by Marshall Design criteria. These results indicate

that a 50% coal dust and 50% coarse sand combination can serve as an effective and economical filler in

dependent on both the type and proportion of filler material incorporated [1]. Fillers contribute to the

reinforcement and stiffening of the asphalt binder as they disperse uniformly within the bitumen matrix.

Commonly used fillers include substances like Portland cement, hydrated lime, granite fines, crushed stone

dust, and fine sand. However, materials such as cement, lime, and granite powder are relatively cost-intensive

and are often prioritized for other construction applications. Alternatively, low-cost substitutes like fine sand,

fly ash, coal dust, and other residual powders that pass through a 0.075 mm sieve are recognized as appropriate

filler alternatives.

Recent investigations have emphasized the feasibility of incorporating industrial and construction byproducts

as fillers in asphaltic compositions. Reclaimed materials such as phosphate residues [2], oil shale fly ash from

Jordan [3], baghouse fines [4], recovered lime sludge [5], municipal solid waste incinerator ash [6], and

workability. Conversely, an excess of bitumen may lead to an overly soft and unstable mix [8]. Fillers increase

interparticle friction and can also undergo chemical interactions with the binder, modifying the rheological

properties of the asphalt mastic [9]. The incorporation of mineral fillers generally improves the elastic stiffness

modulus of asphalt mixtures; however, excessive filler usage may lower mix strength by increasing the binder

demand [10, 11]. Furthermore, the grading of the filler has a significant effect on its contribution to mix

stability and durability.

This research aims to formulate an aggregate-bitumen composite with a carefully controlled air void structure.

A low void content may lead to insufficient binder coating and thin asphalt films, reducing both durability and

compaction ease, whereas excessive voids may result in a lack of structural interlock and instability [12, 13].

Fillers also aid in enhancing temperature resistance and the long-term service life of asphalt mixtures. Strong

the asphalt composite [18].

In Bangladesh, typical filler compositions consist of a mixture of fine sand and crushed stone dust. This study

assesses the feasibility of using a 50:50 blend of coal dust and coarse sand as an alternative filler. Coal dust is

an abundantly available byproduct of industrial processes, and sand is widely accessible. The physical and

mechanical properties of the bituminous mixes with this blended filler were analyzed through laboratory

testing. Results were compared with those obtained using traditional fillers. The findings highlight that a coal

dust- coarse sand blend has considerable potential as a viable, low-cost filler material for bituminous

pavements, supporting sustainable and economical infrastructure development.

1.

The study utilized various materials including black stone chips in Figure: 2, Domar sand in Figure: 3, grade

60/70 bitumen in Figure:4, and fillers like coarse in Figure:5 sand and coal dust-coarse sand. The materials

were tested using international standards such as ASTM and AASHTO. Coarse and fine aggregates were

assessed for specific gravity, sieve analysis, and other properties. Bitumen quality was evaluated through

penetration, softening point, and ductility tests. The Marshall Mix Design method was employed for specimen

and AASHTO T245 standards [19].

Figure 2: Collected Coarse Aggregate (Black Stone Chips)

The Marshall Mix Design method is used for evaluating Hot Mix Asphalt (HMA) by testing the strength,

workability, and rigidity of bituminous mixtures under traffic conditions. The method involves various tests,

including Marshall Stability, flow value, optimum bitumen content, and bitumen film thickness, using

materials like coarse aggregates, fine aggregates, fillers, and bitumen. The process involves preparing samples

with varying bitumen contents, compacting them, and conducting stability and flow tests. The test results for

aggregates, fillers, and bitumen are presented, showing properties such as specific gravity, absorption capacity,

and resistance to degradation. The study also includes a detailed data table comparing the properties of mixes

with fresh filler, RCC waste, brick waste, and combined fillers, along with standard values for Marshall

Stability, flow, VMA, VFB, and air voids. The results provide insights into the quality of the mix and its

Figure 8: Mixing of CA, FA and Filler respectively and heating them on Electric Stove

Figure 9: Marshall Compaction Machine

Figure 10: Adding the bituminous mix into the compaction machine and compacting to make a specimen.

Figure 11: Putting Specimen for Water Bath

Figure 12: Taking SSD Weight after 30 minutes of water bath at 60

C

Table 1: Obtained Data Table for Marshall Mix Design

% BC by Weight

Fresh filler

4.5

2142.8

5

2254.54

The standard unit weight for bituminous mixes, as prescribed by RHD, Bangladesh, falls between 2000-2500

flow and lower stability compared to the fresh filler, which indicates that coal dust may not be as effective in

1. It is obtained to use fresh filler in asphalt mixes, as it provides better stability, optimal air voids, and

Writing - Review and Editing. MAR.: Formal Analysis, Writing - Review and Editing. DT.: Data Curation,

Formal Analysis, Funding Acquisition, Investigation, Methodology, Resources, Visualization, Writing -

Original Draft.

1. Kadeyali: Principles and practice of Highway Engineering.3rdedition (1997).

2. Katamine NM: Phosphate waste in mixtures to improve their deformation. J Transport Eng 2000;

126:382–9.

3. Asi Ibrahim, Assa’ad Abdullah: Effect of Jordanian oil shale fly ash on asphalt mixes. J Mater CivEng

2005; 17:553–9.

4. Lin Deng-Fong, Lin Jyh-Dong, Chen Shun-Hsing: The application of baghouse fines in Taiwan.

7. Huang Baoshan, Dong Qiao, Burdette Edwin G: Laboratory evaluation of incorporating waste ceramic

materials into Portland cement and asphaltic concrete. Constr Build Mater 2009; 23:3451–6.

8. Kalkattawi, H.R: Effect of Filler on the Engineering Properties of Asphalt Mixes, M.S. Thesis, King

Abdul Aziz University, Jeddah, Saudi Arabia. (1993)

9. Anderson, D. A.: Guidelines for use of dust in hot mix asphalt concrete mixtures.”Proc. Association of

Asphalt Paving Technologists, 56, Association of Technologists, St. Paul, MN, 492–516, 1987 Asphalt

Paving

concrete mix properties, Transportation Research Record, 1317, National Research Council,

11. Kandhal, P.S., Lynn, C.Y., and Parker, F.: Characterization tests for mineral fillers related to

performance of asphalt paving mixtures, NCAT Rep. No. 98-2, 1998