Lecture 30B

Question 1

What are Volumetrics

Answer 1

Volumetric are the relationships between mass and volume

Question 2

What is Absorbed Water

Answer 2

Water present in the pervious pores of porous aggregate and particles

Question 3

What is Surface Water

Answer 3

Water present on the surface of aggregate particles (also called free water)

Question 4

A Typical aggregate particle consists of some…

Answer 4

solid material and air voids

Question 5

What does specific gravity depend on?

Answer 5

Volume you assume for the aggregate

Question 6

Difference between SSD, Apparent and Dry specific gravity

Answer 6

Apparent uses the OD weight and bulk used SSD weight (Denominator). SSD uses SSD in both numerator and denominator.

Question 7

Rank Them LARGEST to smallest

Answer 7

Apparent
SSD
Dry

Question 8

What are the two tests needed for specific gravity

Answer 8

Coarse Aggregate
Fine Aggregate

Question 9

Steps of coarse aggregate SG test

Answer 9

ASTM C127
– Dry aggregate
– Soak in water for 24 hours
– Decant water
– Use pre-dampened towel to get SSD condition
– Determine mass of SSD aggregate in bucket
– Determine mass under water
– Dry to constant mass
– Determine oven dry mas

Question 10

Steps on fine aggregate SG test

Answer 10

ASTM C128
– Dry aggregate
– Soak in water for 24 hours
– Spread out and dry to SSD
– Add 500 g of SSD aggregate to pycnometer of known volume
* Pre-filled with some water
– Add more water and agitate until air bubble have been removed
– Fill to line and determine the mass of the pycnometer, aggregate
and water
– Empty aggregate into pan and dry to constant mass
– Determine oven dry mass

Question 11

What are the effects of gradation and size in bituminous mixes

Answer 11

Workability
Layer thickness
Thickness of lift
Stability
Stiffness
Resistance to deformation
Fatigue strength
Durability
Permeability
Surface Texture and frictional resistance

Question 12

What are the two methods of tests for gradation?

Answer 12

Wet and Dry Sieve Analysis

Question 13

What are the 3 methods of reporting results for gradation?

Answer 13

% passing
%retained
%passing/retained

Question 14

Coarse Aggregate Definition

Answer 14

Retained on 4,75mm (No.4) sieve

Question 15

Fine Aggregate Definition

Answer 15

Passing 4.75mm (No.4) Sieve

Question 16

Mineral FIller Definition

Answer 16

At least 70% pass 0.075mm sieve

Question 17

Agregate Gradation Definition

Answer 17

The distribution of particle sizes expressed as a percent of total weight. This is determined by sieve analysis

Question 18

Washed Sieve analysis steps

Answer 18

Dry aggregate and determine mass
Wash and decant water through 0.075 mm
sieve until water is clear
Dry aggregate to a constant mass

Question 19

Mechanical Sieve Analysis Steps

Answer 19

Place dry aggregate in standard stack
of sieves
– Place sieve stack in mechanical shaker
– Determine mass of aggregate retained
on each sieve

Question 20

what is the name of the maximum density line

Answer 20

Fuller’s Curve

Question 21

Definition of Maximum aggregate size

Answer 21

On size larger than nominal size

Question 22

Definition of Nominal Maximmum aggregate size

Answer 22

One size larger than the first sieve to retain (Cummulative) more than 10%

Question 23

what are the 4 types of gradations

Answer 23

Dense Graded
Open Graded
Gap Graded
Uniformly Graded

Question 24

Whats the most common HMA and what is it’s properties?

Answer 24

Dense Graded,

Grain-to-grain contact
Low void content
High density
High stability if
confined
High stability
unconfined
Difficult to compact

Question 25

What is Open Graded?

Answer 25

Refers to a gradation that contains only a small percentage of aggregate particles in the small range

Question 26

What is Fine Gradation?

Answer 26

A gradation that, when plotted on the 0.45 power gradation graph, falls mostly above the 0.45 power maximum density line.

Question 27

What is Coarse Gradation?

Answer 27

A gradation that, when plotted on the 0.45 power gradation graph, falls mostly below the 0.45 power maximum density line

Question 28

what happens if the max size is larger?

Answer 28

Increases strength improves skid resistance Increases volume and surface area of agg which decreases required AC content Improves rut resistance Increases problem with segregation of particles

Question 29

What happens if the max size is smaller?

Answer 29

Reduces segregation Reduces Road Noise Decreases Tire Wear

Question 30

What are the reasons to blend aggregates

Answer 30

Obtain desirable gradation Single natural or quarried material not enough Economical to combine natural and process materials

Question 31

what are the 3 sources of aggregate stocks

Answer 31

1. stone comes from crushed bedrock, 2. sand comes from natural deposits, 3. mineral filler comes from the bottom of the crusher (dust)