CO129-421 - Governor Sir May - 1915 [3-4] — Page 55

CO129 Colonial Office Hong Kong Records 理藩院香港檔案 All

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COPY.

(To accompany closure 1.)

Specification No. 7.

54

Construction of an Asphaltic Concrete Surface 14 inches thick.

MATERIALS.

1. The Hineral aggregate shall consist of finely crushed stone and filler, so proportioned that the mixture shall conform to the following

grading:-

Passing screen

of mesh.

100

200

92898888

Retained by screen

of mesh.

100%

between 8% and

11

8.5.

11.5

·

16.5.

22.5

10

4

7

20

12

17

30

#

6

40

#

2.5.

5.5

50

3

10

6

80

100

2.5 * 1.5 #

6.5

2.5

200

1 3 12

6

18

The stone shall not show a loss greater than 4% by weight when

subjected to the standard Deval Abrasion Test; and shall not show a

fracture under 25 blows when subjected to the Standard Impact Test.

2. The filler shall be pulverised limestone or Portland cement. All

of the filler shall pass a 50 mesh to the inch screen and at least 65%

shall pass a 200 mesh to the inch screen.

3. The cementing material shall be an asphaltun manufactured from an

asphaltic base crude oil and shall meet the following test:-

(a). The asphaltum shall have a penetration of from 26 to 75°

which shall be varied within those limits to adapt it to the

particular climatic, traffic, or other conditions to which it

is to be subjected.

(b). The asphaltum shall have a ductility of at least 100

centimeters when a briquette of 1 square centimeter cross

section is elongated at the rate of 1 centimeter per minute at a temperature of 25° C.

(c). When 20 grams of the asphaltum are heated for 5 hours at a

temperature of 163° C. in an oven, there must not be volatiliz

-ed

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