Page 66 - DILMUN 14

As for thc ixing method, two possibilities have bcen considered :

1. 'o mix all th١e constitucnts in dry conditions (to prevent the gypsun from
sctting) a١d ١p add water just before use.

2. o nix the wet "coarse stuff' and to add gypsum just before use. he mixing
procedure turned out to affect considerably the mortar strength, the first
method being more effective. Compression tests (23) have given the following
results :

CRUSHING SRENGH (kg / mm?)

DRY MIX After 3 days After 24 days
6.8 7.0 29.6 34.7

wE MIX 3.8 5.0 24.5 25.5

he mixing method established, this mortar has been used to repair the arch
between the two chambers of the NW Bastion. During work, the advantages of
using gypsum have become obvious: on the one hand, it improves workability by
giving an initial, rapid setting; on the other hand, it balances the lime shrinkage by
its expansion.

OHER MIXE‫ ﺶ‬USED IN BAHRAIN FOR RESORAION WORK

Parthian Fortress : It has been partially restored in 1982-83. According to the
report of the architect C. Lalande (Mission Archeologique Francaise), limelcement
mixes have been used, with the following proportions :

4 White cement
1 Sulphate cement
4 Lime
15 Washed sand
5 hin Gravel

Pimgents were added to get the right colour.

Arad Fort : It has been restored in 1985-87 by Dr. A٠ Walls with the supevrision
of Sir Bernard Feilden. According to Dr. Walls' book',a coarse stuff was prepared
with Haji Hassan AI AIi lime, unwashed sand rfom site excavations, unwashed
gravel from the same material, following this ratio :

1 Lime putty
2 Sand
2 Large aggregates
0.5 Gypsum (added at the last moment to the wet mix)

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