Pavement Flashcards
(35 cards)
refers to the topmost layer of a pavement structure—the part that comes into direct contact with vehicle traffic.
Pavement surfacing
to provide a safe, all weather skid resistant and dustproof surface of adequate ride quality, and to protect the pavement from wear and the effect of moisture.
Bituminous Surfacing
a bituminous material is sprayed on to a prepared pavement, and then usually (but not always) covered with aggregate.
Sprayed Work
a mixture of bituminous binder and aggregate which form a surface course, and sometimes part of the base and subbase of the pavement.
Asphalt Work
Used on urban roads, motorways, roundabouts, and high-traffic areas for smoothness, durability, and noise reduction.
Asphalt work
This is the most common surface treatment on rural and secondary roads in New Zealand due to its cost-effectiveness.
Sprayed work
It is a bitumen to which a fluxed oil has been added to produced a reasonably long-term reduction in its viscosity.
Fluxed bitumen
is a special petroleum distillate, designed for long-term blending with bitumen.
Flux oil
is a special petroleum distillate, designed for long-term blending with bitumen.
Flux oul
while it can soften bitumen temporarily, is volatile, evaporates quickly, and can damage the bitumen structure if used improper
Diesel
There are mainly three types of Bitumen used:
Cutback
Emulsion
Penetration grades
is used in sprayed sealing and cold conditions where rapid curing is required
Cutback
are safer and more environmentally friendly, especially for urban and cooler regions (Water with an emulsifying agent used for dilution).
Emulsion
are harder and typically used in hot mix asphalt.
Penetration grade
a preparatory step in road construction where a thin layer of bituminous material (usually a cutback bitumen or fluxed bitumen) is applied to a prepared base layer before the final bituminous surfacing is laid.
Priming
is a surface treatment used on roads to protect and enhance existing pavement.
Seal coat
It may be used as a temporary treatment to reduce dust, or to avoid loss of pavement material or excessive maintenance.
Dust laying
Its purpose is to increase the binder content at the surface, to rejuvenate the existing binder, to waterproof or extend the life of the surface, and to ensure the retention of the covering aggregate.
Surface enrichment
The most common types of asphalt treatments are
a.)Dense – graded asphalt
b)Open – graded asphalt
c)Gap – graded asphalt
d)Stone – mastic asphalt
mix with a range of aggregate sizes that fit tightly together.
•Typically used in general road surfacing and urban areas.
Dense graded asphalt
Mix with reduced fines and higher void content, allowing water to drain through.
Open graded asphalt
Mix where certain intermediate aggregate sizes are omitted, resulting in high binder content and aggregate interlock.
Gap graded asphalt
A gap-graded, high-stone-content mix with a strong skeleton held together by a rich binder and fibre stabilisation.
Stone Mastic Asphalt (SMA)
Advantages of DGA
Lower initial cost
