6. Key Viva/Short Questions (Based on Your Report) Why ductility is important for flexible pavements? What happens if bitumen has low penetration? (Too hard — cracks). Why angular aggregates are preferred in surface courses? What are the safety implications of flash & fire point? Why is specific gravity of bitumen measured? ire Lesle RUM Leo (el geMo a Os). a cao ee How to reduce loss on heating during storage? Why flakiness index should be controlled?rea ame Pret eu ee nem ud eee Ren ert ACU ne cece Pree Met eu come eRe eles ecu ee Pe ee auc Ltd IF penetration is low, bitumen becomes too hard and brittle, leading to cracks in the pavement under traffic PU Rua ecco St ies ee ae ected Angular aggregates provide better interlocking, higher skid resistance, and improved stability in surface Peete enous Ee ered ee eg i a oe Flash and fire point values indicate the temperature at which bitumen can produce flammable vapors. Knowing them ensures safe heating, handling, and storage of bitumen to prevent fire hazards. ST eee rd Tune Specific gravity helps to determine the weight-volume relationship of bitumen, which is important for mix Cee Mee eu Re Renee eee eee ee co te CARD tut cea * Not suitable for cohesionless soils with high gravel content. Results are highly affected by moisture content and compaction. OMe d ecte nac Pues * Limited mainly to flexible pavement design. 7. How to reduce loss on heating during storage? Cols Ree ae rt ae seen Rare ce * Use proper closed containers to minimize oxidation and evaporation. SUS geen aR ec PRO g i enue te kent cd High flakiness index leads to weak planes, poor interlocking, more voids, and higher cement/asphalt demand. Controlling it ensures better strength, stabi’ J, and durability of the construction.1. Aggregate Tests (a) Aggregate Impact Value (AIV) Test Ct ae eee Age OP Cusco rece cd eerie aun h Oy REN eed Ser ocr Pe Tee ated sey rv Aa pane) rae a Limits: < 30% for road surfacing, < 25% for wearing surfaces. Ty eaeiteod se A ener eee Cee a Uae ets(b) Aggregate Crushing Value (ACV) Test Purpose: Strength of aggregate under compressive load. Procedure: e Place aggregates in cylinder. ¢ Apply compressive load gradually. « Measure fraction passing 2.36 mm sieve. Zen Le) 16h a oa x 100 Limits: < 25% (wearing surface), + 45% (other layers). Importance: High ACV — aggregate easily crushed — unsuitable.(c) Flakiness & Elongation Index BT tees ston Corset © Pass aggregates through standard gauge slots. * Weigh flaky/elongated particles. St OM coos Fi=— i * Elongation: ELT ee © Limits: Fl + El < 30%. + Importance: Too many flaky/elongated — weak & unstable pavement.(d) Angular Number Test * Purpose: Indicate * Result: Higher angularie-em td) (a) Penetration Test (ASTM D5) Purpose: Hardness/consistency. Procedure: Standard needle penetrates bitumen at 25°C, 100 g, 5 sec. Result: Penetration grade (e.g., 60/70). Importance: Lower penetration = harder bitumen (for hot climates).(b) Softening Point Test (Ring & Ball, ASTM D36) * Purpose: Temp at which bitumen softens. CM a Colac « Bitumen in brass rings. * Steel balls placed. CMa alle ea ee ite eo mel) Belt (one lcm Limit: Temp difference between 2 rings < 1°C. Result: Softening point ~ 40-60°C. Importance: Higher value = better performance in hot weather.ar PED) Purpose: Measures stretching capacity before break. Eyres tis OM el sR rea nim edie trates Cer een R ca nel os OR eevee elie tel Nas Limit: > 75 cm. Error & Correction: If floating - SG < water, correct by adding methyl alcohol. Importance: Higher ductility + more flexible pavement.(d) Flash & Fire Point Test (ASTM D92) e Purpose: Safety in storage/handling. * Procedure: Heat sample in open cup. Materelel ire utr LMC) Flash point — temp vapors ignite. Fire point — temp sustains burning. Typical Values: Flash > 175°C, Fire > 200°C. Importance: Prevents fire hazards in road construction.(e) Loss on Heating Test Purpose: Measures hardening/volatilization. Procedure: Heat sample at 163°C for 5 hrs. etna a %Loss = Wd Limit: < 1%. Importance: Excessive loss = brittle bitumen.(ecm Cy Tort ere n sium Cat mek cle Se B-A (B— A) —(C— D) here A ere eel yom B = Wt. of pyc + bitumen. C = Wt. of pyc + bitumen + water. DAW ia (mem lca * Importance: Needed for mix design (weight-volume conversion).* 3. Soil / Roadway Test California Bearing Ratio (CBR) Test Purpose: Strength of soil subgrade. Procedure: © Penetrate piston into soaked soil at 1.25 mm/min. © Record load at 2.5 mm & 5 mm penetration. ets x 100 IP fol eJ 10 sa Std Loads: 2.5 mm — 13.3 kN; 5 mm — 20 kN. aie oto ® < 5% — poor subgrade. Cd Yen lL Cri ewe cote4. Traffic Flow & Roadway Capacity STU Chae imi ile Lime (ers Beol te Lelia Capacity Formula (highway): C=N x Crane X fu X fe Signalized Intersection (Approach Capacity): ar 3B a= where g = green time, c = cycle time, s = saturation flow.Lr Mi ha By -eare La) Purpose: To determine optimum binder content (OBC). Larele sola See ee see ice Aas * Test stability, flow, density, air voids, VMA, VFB. Graphs (6): Stability, Flow, Unit Weight, Air Voids, VMA, VFB vs % Bitumen. Co): fee Va er onan see cee Meer Sete