Q$.4$

You work for a highway engineering firm where your role is to bring

benefits to projects by incorporating non$-$specified materials such

as secondary aggregates into road pavement design.

You identify two potential foundation materials for use in the

foundation of a new single carriageway road pavement that is $10$

$km$ long, has an average paved width of $9\mathrm{.}3m,$ and has a design

traffic loading of $20$msa. The two materials are:

Type $1$ aggregate certified as Foundation Class $2(E=100$

MPa $),$ sourced from a distant quarry.

Locally available secondary aggregates with a stiffness of $E$

$=56$ to $60$MPa.

a$)$ For both potential foundation materials, use the Standard

Upper Pavement Design method and nomograph in

Worksheet Q$.4$ to calculate the total thickness and total

volume of upper pavement material, assuming this will be

EME$2$ asphalt material.

$[6$ marks$]$

b$)$ Discuss the relative merits and disadvantages of the two

designs.

$[4$ marks$]$