Construction Materials Midterm 1
Questions with Verified Answers
HMA - ANSWERSHot Mix Asphalt
subgrade - ANSWERSThe soil prepared to support a pavement structure. It is the
foundation of the pavement structure.
subbase - ANSWERS(optional) layer below the base course.
base course - ANSWERSThe layer of material immediately beneath the surface or
intermediate course. It may be composed of crushed stone, crushed slag, crushed or
uncrushed gravel and sand, or of a stabilized material that uses asphalt or cement with
aggregate.
surface course - ANSWERSThe top or wearing layer of the asphalt pavement.
pavement structure - ANSWERSA pavement, including all of its courses of asphalt-
aggregate mixtures, or a combination of asphalt courses and untreated aggregate
courses, placed above the subgrade.
dense graded mixture - ANSWERSA pavement surface course that has an aggregate
particle size distribution such that when it is compacted, the resulting voids between the
aggregate particles, expressed as a percentage of the total space occupied by the
material, is relatively small.
open graded mixture - ANSWERSA pavement surface course that consists of a high-
void, asphalt plant mix that permits rapid drainage of rainwater through the course and
out the shoulder. The mixture is characterized by a large percentage of one-sized
course aggregate.
sources of asphalt - ANSWERS-natural asphalt deposits
-petroleum asphalts
asphalt cements - ANSWERS-refinery produced material
-air blown asphalt cements
cutbacks - ANSWERS-asphalt cements cut with petroleum solvents
emulsions - ANSWERS-mixture of asphalt cement, water, and emulsifying agent
Source Aggregate Properties - ANSWERStoughness, soundness, deleterious material
, consensus aggregate properties - ANSWERScourse aggregate angularity, fine
aggregate angularity, flat/elongated materials, clay content
Mixture properties (we want) - ANSWERSStability
Durability
Impermeability
Workability
Flexibility
Fatigue resistance
Skid resistance
Mixture properties (we dont want) - ANSWERSRutting or shoving
Cracking or raveling
Permeable pavements
Difficulty in handling
Too much rigidity
Fatigue cracking
Slick pavement surface
disintegration - ANSWERSraveling and reduced skid resistance
load related cracks - ANSWERS-inadequate tensile or shear strength
-weak supporting layers
-high wheel loads/tire pressures
rutting - ANSWERSlongitudinal surface depression in the wheel path
plastic movement - ANSWERSdepression in the wheel path with humps in either side
consolidation/densification - ANSWERSdepression in the wheel path without any humps
mechanical deformation - ANSWERSsubsidence or densification in the unbound base
or subgrade and accompanied by a cracking pattern
bleeding/flushing - ANSWERSextrusion of asphalt cement at the pavement structure
-excessive amounts of asphalt
-low air voids or low viscosity asphalt for climate
-moisture damage/stripping
raveling - ANSWERSremoval of hma surface by dislodging of aggregates
-inadequate density
-low asphalt cement content
-dirty aggregate
Adhesion between the asphalt and aggregate
-high air void content
-asphalt film thickness
Questions with Verified Answers
HMA - ANSWERSHot Mix Asphalt
subgrade - ANSWERSThe soil prepared to support a pavement structure. It is the
foundation of the pavement structure.
subbase - ANSWERS(optional) layer below the base course.
base course - ANSWERSThe layer of material immediately beneath the surface or
intermediate course. It may be composed of crushed stone, crushed slag, crushed or
uncrushed gravel and sand, or of a stabilized material that uses asphalt or cement with
aggregate.
surface course - ANSWERSThe top or wearing layer of the asphalt pavement.
pavement structure - ANSWERSA pavement, including all of its courses of asphalt-
aggregate mixtures, or a combination of asphalt courses and untreated aggregate
courses, placed above the subgrade.
dense graded mixture - ANSWERSA pavement surface course that has an aggregate
particle size distribution such that when it is compacted, the resulting voids between the
aggregate particles, expressed as a percentage of the total space occupied by the
material, is relatively small.
open graded mixture - ANSWERSA pavement surface course that consists of a high-
void, asphalt plant mix that permits rapid drainage of rainwater through the course and
out the shoulder. The mixture is characterized by a large percentage of one-sized
course aggregate.
sources of asphalt - ANSWERS-natural asphalt deposits
-petroleum asphalts
asphalt cements - ANSWERS-refinery produced material
-air blown asphalt cements
cutbacks - ANSWERS-asphalt cements cut with petroleum solvents
emulsions - ANSWERS-mixture of asphalt cement, water, and emulsifying agent
Source Aggregate Properties - ANSWERStoughness, soundness, deleterious material
, consensus aggregate properties - ANSWERScourse aggregate angularity, fine
aggregate angularity, flat/elongated materials, clay content
Mixture properties (we want) - ANSWERSStability
Durability
Impermeability
Workability
Flexibility
Fatigue resistance
Skid resistance
Mixture properties (we dont want) - ANSWERSRutting or shoving
Cracking or raveling
Permeable pavements
Difficulty in handling
Too much rigidity
Fatigue cracking
Slick pavement surface
disintegration - ANSWERSraveling and reduced skid resistance
load related cracks - ANSWERS-inadequate tensile or shear strength
-weak supporting layers
-high wheel loads/tire pressures
rutting - ANSWERSlongitudinal surface depression in the wheel path
plastic movement - ANSWERSdepression in the wheel path with humps in either side
consolidation/densification - ANSWERSdepression in the wheel path without any humps
mechanical deformation - ANSWERSsubsidence or densification in the unbound base
or subgrade and accompanied by a cracking pattern
bleeding/flushing - ANSWERSextrusion of asphalt cement at the pavement structure
-excessive amounts of asphalt
-low air voids or low viscosity asphalt for climate
-moisture damage/stripping
raveling - ANSWERSremoval of hma surface by dislodging of aggregates
-inadequate density
-low asphalt cement content
-dirty aggregate
Adhesion between the asphalt and aggregate
-high air void content
-asphalt film thickness
