Chaturabong, Preeda

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Chaturabong, Preeda
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preeda.ch@kmitl.ac.th

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    Rheological, adhesive, and chemical characterization of asphalt mastic modified with spent coffee grounds: A comparative study with limestone filler
    (2026-06-01)
    Thairueng, Manita
    ;
    Chamwon, Suwaphit
    ;
    Hutabarat, Multazam
    ;
    Chaturabong, Preeda
    Spent coffee grounds (SCG) were evaluated as an organic filler in asphalt mastic at 10 %, 15 %, and 20 % by volume, benchmarked against limestone (LM). The experimental program combined DSR temperature sweeps, pull-off adhesion tests on basalt, granite, and marble substrates, SARA fractionation, and SEM, performed under fresh, RTFOT-aged, and PAV-aged conditions. At 20 wt% replacement, SCG reduced the complex shear modulus G* from 3637 to 2885 kPa at 16 °C (−21 %) and lowered the isostiffness temperature from 31.22 °C to 25.43 °C after PAV aging (−5.79 °C), while limestone at 20 wt% raised G* to 6461 kPa (+78 %). The rutting factor G*/sinδ decreased by 19–23 % with SCG and increased by 71–80 % with LM at 64 °C, whereas the fatigue factor G*sinδ at 25 °C dropped by 18–22 % with SCG, indicating improved fatigue resistance potential. Limestone mastics exhibited 25–83 % higher pull-off force than SCG ( p < 0.05, all 18 comparisons, Benjamini–Hochberg-corrected), yet SCG mastics maintained moisture retention of 83–97 % on basalt, comparable to LM (75–97 %). Failure mode analysis showed all mastics cohesive under dry conditions, with SCG transitioning to adhesive failure under moisture exposure (notably at 15–20 % SCG on marble and granite after PAV aging). SARA analysis confirmed aromatics rose from 60.6 % to 65.7 % and asphaltenes fell from 10.7 % to 8.2 % with increasing SCG, yielding an Instability Colloidal Index decrease from 0.187 to 0.154. These results establish SCG not as a direct limestone substitute but as a complementary modifier suited to fatigue-prone warm-climate binder courses and hybrid SCG–LM filler blends, offering environmental benefits through agricultural waste valorization.
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    Mineral filler characteristics and non-Newtonian viscosity of asphalt mastic at high temperature: A response surface methodology approach
    (2026-12-01)
    Chamwon, Suwaphit
    ;
    Hutabarat, Multazam
    ;
    Chaturabong, Preeda
    Asphalt mastic—composed of asphalt binder and mineral filler—strongly governs the high-temperature viscosity of asphalt concrete during mixing and compaction. This study investigates the effects of four mineral fillers (granite, limestone, shale, and pumice) on the viscosity and flow behavior of asphalt mastics at elevated temperatures (130–170 °C). Comprehensive filler characterization was performed, encompassing morphological analysis by scanning electron microscopy (SEM), physical property evaluation (particle density, specific surface area, and Rigden voids), hydrophilic coefficient determination, particle size distribution by laser diffraction, and mineralogical identification by X-ray diffraction (XRD). Response surface methodology (RSM) with a central composite design (CCD) was employed to model the combined effects of temperature (130–170 °C), filler content (5–30% by volume), and rotational speed (10–30 RPM) on apparent viscosity measured by a Brookfield rotational viscometer. The non-Newtonian index, derived from the power-law (Ostwald–de Waele) model, was used to classify flow behavior. Results demonstrate that temperature and filler content are the dominant parameters governing viscosity, while rotational speed controls the degree of non-Newtonian behavior in a filler-dependent manner. A critical transition from quasi-Newtonian to pronounced non-Newtonian flow was identified at 15–20% filler content by volume, coinciding with a sharp increase in the effective solid volume fraction that approaches the colloidal packing threshold (φ* ≈ 32–34%). Pumice exhibited the strongest shear-thickening (n up to 1.22) while granite showed consistent shear-thinning (n ≈ 0.88–0.94), with limestone and shale showing mixed behavior. Pumice and shale produced the strongest viscosity stiffening, consistent with greater binder immobilization due to their higher Rigden voids. AASHTO T316 workability analysis indicates that under base-binder conditions, the maximum filler content within practical mixing limits at 160 °C is approximately 30% for granite and limestone but only ∼22% for pumice. The validated quadratic RSM models (R² = 0.84–0.96) provide a practical framework for optimizing filler selection and processing temperatures in asphalt mixture design.