Test: Highway Materials, Construction & Maintenance - 2 - Civil Engineering (CE) MCQ

Rapid curing cutbacks are bitumens, fluxed or cutback with a petroleum distillate such as neptha, or gasoline which will rapidly evaporate after using in construction, leaving the bitumen binder.

Bitumens are derived from the destructive distillation of crude petroleum oils that give substantial amounts of heavy residue, typically from 10–50%, although crude oils giving a greater yield of residue are sometimes used. 

Bituminous carpet: surface course
Mastic asphalt: Surfacing for bridge deck slabs
Sheet Asphalt: wearing or surfacing course
Bitumen Bound Macadam: base course

Among the five grades of tar RT-1 has least viscosity and then viscosity increases with number,
RT-1 : Surface painting under cold weather
RT-2 : Surface painting under Indian conditions
RT-3 : Surface painting, renewal coats and premixing chips for top course and light carpets
RT-4 : Premixing tar macadam in base course
RT-5 : Has highest viscosity and used for grouting

Penetration test determines the hardness or softness of bitumen by measuring the depth in tenths of a millimetre to which a standard loaded needle wilt penetrate vertically in five seconds.

Flow value is the deformation of specimen in 0.25 mm units up to the maximum load. It should be between 8 to 16.
Marshall stability value is the maximum load in kg before failure. Its minimum specified value is 340 kg. The stability first increases and then decreases with increase in bitumen content.
Unit weight also increases initially and then decreases.
Percentage of voids in total mix always decrease with increase in bitumen content.
The percentage of voids filled with bitumen increase with increase in bitumen content. But the graph is convex upward.

According to iS:2720 the Plasticity Index (PI) of binding material in WBM for base/subbase should be less than 6%.

Curve (a) → % air voids in total mix (V_v) Curve (b) → VMA ( % voids in mineral agg)
Curve (c) → unit weight (g/cc)
Curvo (d) → Flow value

Penetration = (1/10) x reading on scale.