ASPHALT - CONCRETE QUESTIONS AND CORRECT ANSWERS

ASPHALT - CONCRETE QUESTIONS
AND CORRECT ANSWERS
Jaw crushers are typically employed as tertiary units because of their large energy-storing flywheels
and high mechanical advantage. ✅✅ CORRECT ANSW-False



Jaw crushers do not handle slabby material well. ✅✅ CORRECT ANSW-True



The space between the jaws increases as the stone travels downward under the effect of gravity and
the motion of the movable jaw, until the stone ultimately passes through the lower opening. ✅✅
CORRECT ANSW-False



Jaw crushers are usually designed with the toggle as the strongest part. ✅✅ CORRECT ANSW-
False



Double-toggle Blake-type jaw crushers are so small and light that they lend themselves to portable
applications. ✅✅ CORRECT ANSW-False



Gyratory crushers are the most efficient of all primary-type crushers. ✅✅ CORRECT ANSW-True



If a gyratory crusher is used as a secondary crusher, the size selected may be dictated by the size of
the rock from the blasting operation or by a desired capacity. ✅✅ CORRECT ANSW-False



When a gyratory crusher is used as a primary crusher, increasing its speed within reasonable limits
may increase the capacity. ✅✅ CORRECT ANSW-False



Gyratory crushers with straight concaves are used as secondary crushers, whereas those with
nonchoking concaves are commonly used as primary crushers. ✅✅ CORRECT ANSW-False



Cone crushers are used as primary crushers. ✅✅ CORRECT ANSW-False



Cone crushers have a shorter cone (less height) than gyratory crushers. ✅✅ CORRECT ANSW-
True

,The amount of processing required to produce suitable aggregate materials for construction
purposes depends on the nature of the raw materials available and the desired attributes of the end
product. ✅✅ CORRECT ANSW-True



Smaller commercial aggregate plants are the major source of crushed stone for the construction
industry in metropolitan areas. ✅✅ CORRECT ANSW-False



Crushing plants use step reduction because the amount of size reduction accomplished is indirectly
related to the energy applied. ✅✅ CORRECT ANSW-False



When the difference between the size of the feed material entering the crusher and the size of the
crushed product is small, a large amount of energy is required. ✅✅ CORRECT ANSW-False



Cone crushers rotate at a higher speed than gyratory crushers. ✅✅ CORRECT ANSW-True



Because the material is dragged against the liner, single-roll crushers are economical for crushing
highly abrasive materials. ✅✅ CORRECT ANSW-False



Roll crushers are used for additional reduction in the size of stone after the output of the blasting
operation has been subjected to one or more stages of prior crushing. ✅✅ CORRECT ANSW-True



Single-roll crushers can handle sticky materials. ✅✅ CORRECT ANSW-True



The ability to easily accommodate a pavement section to staged construction and to recycle old
pavements, and the fact that mix designs can be adjusted to use local materials, are three critical
factors favoring the use of asphalt materials. ✅✅ CORRECT ANSW-True



The mixing plant, trucks, asphalt paver, and compactors must be unsynchronized for an efficient,
cost-effective operation. ✅✅ CORRECT ANSW-False



Asphalt pavements are constructed as layered systems. ✅✅ CORRECT ANSW-True



The aggregate characteristics and amount of asphalt cement are designed specifically to match the
needs of the binder and surfacing courses. ✅✅ CORRECT ANSW-True

, Pavements are designed to provide a stable, smooth, and skid-resistant riding surface. ✅✅
CORRECT ANSW-True



The asphalt mixture must seal the base, subbase, and subgrade to prevent water intrusion. ✅✅
CORRECT ANSW-True



Vehicle fuel efficiency, ride quality, and safety are unaffected by surface tension. ✅✅ CORRECT
ANSW-False



The purpose of blending aggregates and asphalt cement is to achieve a final product that satisfies all
of the objectives. ✅✅ CORRECT ANSW-True



Good aggregates and their proper gradation are critical of the mix's performance. ✅✅ CORRECT
ANSW-True



Ideally, an aggregate gradation should be provided that requires the maximum amount of expensive
asphalt cement. ✅✅ CORRECT ANSW-False



For the production of an asphalt concrete mix, a blend of aggregates must be used such that the
combined aggregate gradation will fall within the control points. ✅✅ CORRECT ANSW-True



Gradations that violated the restricted zone performed differently to or worse than the mixes having
gradations passing outside the restricted zone. ✅✅ CORRECT ANSW-False



If a single stockpile were created with the desired gradation, the smaller aggregates would tend to
separate from the larger aggregates. ✅✅ CORRECT ANSW-False



The pavement performance would not suffer if asphalt concrete is made from a segregated
stockpile. ✅✅ CORRECT ANSW-False



To reduce the segregation problem, aggregates are stored in stockpiles of different sizes. ✅✅
CORRECT ANSW-False