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١ay be comparcd to he "١uss" sonmclines incorrcctly idcntificd with gypsum -
which is no longer made in Bahrain, although a f٥٧ kilns still cxist in the Awali

re٨.

it is finally nocworthy that the large amount of salt (NaCl) precipitated within
the mortar seems to contribute to its actual strength: considering that after 24
hours soaking in water the sanples completely disintegrated", it can be almost
imagined that Arad fort is actually held together by the salt itself.

MAERIALS FOR RESORA ION WORK
Seeking for materials suitable for conservation and restoration work, the

following considerations can be made:

LIME
A'Al Lime : often referred to as 'Noura', this lime is produce in A'Ali village.
Oddly enough, the kilns where the limestone is calcinated are dug into the famous
burial mounds. At chemical analysis, it turned out to be extremely poor in Calcium
Oxide (about 50%).

Haii Hassan At Ai Lime : the limestone is quarried in Askar. It is available in
very reactive lIumps of quick lime.

AISCO Lime : the limestone, also from Askar quarry, is burnt in the rotative kiln
of the Arab Iron and Steel Company. It is available in hydrated powder.

None of the samples examined? complies with the British Standards for High
Calcium Lime; however, AISCO and Haji Hassan limes are closer in meeting the
specifications. Mortar cubes made with these two limes proved to withstand a
compression stress twice as great as those made with AAli lime.

Since Haji Hassan lime is suitable for being slaked on site whereas AISCO lime
can be mixed dry with the other components, the choice will basically depend on
the required method of mixing.

GYPSUM
he gypsum imported from Saudi Arabia is a very good hemihydrate (plaster of

Paris) and it is broadly used throughout the island.

At chemical analysis' it appears to match nearly all the requirements of the ٠
British Standards.

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