UFC 3-250-03

15 May 2001

Surface Area Factors

Square Meters Per

Square Feet per

Sieve Size

Kilogram of Aggregate

Pound of Aggregate

9.5 millimeter (3/8 inch)

0.00409

0.02

4.75 millimeter (No. 4)

0.00409

0.02

2.36 millimeter (No. 8)

0.00819

0.04

1.18 millimeter (No. 16)

0.01639

0.08

600 Fm (No. 30)

0.02867

0.14

300 Fm (No. 50)

0.06144

0.30

150 Fm (No. 100)

0.12289

0.60

75 Fm (No. 200)

0.32771

1.60

(2) If the specific gravity of the asphalt is not known, the asphalt required to coat the aggregate

may be calculated by assuming SGA = 1.0. The error that results from assuming SGA = 1.0 is small and

will not greatly affect the final design requirements.

b. Aggregate absorption. The absorption requirements of the aggregate are determined by using

the Centrifuge Kerosene Equivalent (CKE) described in ASTM D 5148. In this test, 100 grams of minus

4.75 millimeter (No. 4) material is centrifuged in the presence of kerosene for 2 minutes. The amount of

kerosene retained by the aggregate is assumed to approximate the amount of asphalt that the

aggregate will absorb. The kerosene absorbed (KA) by the aggregate is converted to a percentage of

the dry weight of the aggregate.

c. Total asphalt.

(1) The total asphalt requirement is obtained by adding the percent asphalt required for the film

thickness and the percent asphalt required for absorption. All percentages are based on the dry weight

of the aggregate. The total is obtained as follows:

(eq E-2)

or

(eq E-3)

where

AR = total asphalt required, percent of dry aggregate weight

KA = kerosene absorbed, percent of dry aggregate weight

C-2

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