amount of cement was mixed (Fig. 7). The binding agent was an epoxy resin which had a pot life not exceeding 2 hours wtih 30 kilogram mortar bat- ches.
The epoxy-combined aggregate ratio found to be most suitable after trial mixes was about 1 to 9. Although the mortar at first sight appeared to be very dry it was nevertheless possible to obtain satisfactory compaction by placing in layers and ramming, which also brought sufficient epoxy to the surface for trowelling to a smooth dense finish. Sufficient epoxy remain- ed after mixing the mortar for priming all surfaces immediately prior to placing the mortar.
Thus far the behaviour of the nosings under heavy traffic on the Lai Chi Kok Interchange flyover has been encouraging; a smooth riding joint was obtained because the asphalt surfacing was laid and compacted continuously over the expansion joint and the width required for the epoxy nosings was sawn-out of the fully-compacted sur- facing.
Bridge deck railings are of rolled hollow section with high-yield steel for the posts and top rail and mild steel for the two lower rails. There were no difficulties in fabricating these railings in Hong Kong and suitable electrodes were chosen for welding the high yield steel.
Railings were erected and tem- porarily supported to the required alignment until adequate length was available for checking by measurement
Placing epoxy mortar in layers for compac- tion by ramming
and by eye; in this way it was possible Laying and compacting final layer of roadstone
Completed articulation joint
200 100
100
40
To
bo
50
ગ્
24
10
Zoo
joo
32 36 23 18 14 1078Ž¿¡
A 2 3
ૐ
100
مو
60
R
50
40
30
20
Veits
PROPORTION:
Dust
4%
Marshall
PROPORTION:
"
15%
Cement
3%
Flow
0.13
3/8" + 3/16" 31%
Bitumen
6%
Air voids
5%
11⁄2"
"
fine
47%
Marshall
stability
1,600 lbs
15%
20% 3/8" + 3/16" 15% Fine
45%
Dust Cement Bitumen Marshall
stability
25% 25%
4.8%
Marshall Flow Air voids
0.12
7%
1,800 lbs
Fig. 8.
Rolled asphalt wearing course (Typical grading)
Fig. 9.
38
Rolled asphalt base course (Typical grading)
Far East BUILDER, February 1971
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