Characterization of the clay masonry units and construction technique at the ancient city of Nippur

The experimental results show that the ancient brick units and stone samples exceed the tolerance and range of dimensions limits recommended by current EN Standards. Lower density values were recorded for the ancient brick units compared with that for both modern clay brick and stone specimens and these values showed agreement with the modern classification of high density (HD) units. Approximately similar values of compressive strength were observed for both ancient brick units and natural stone samples reaching about 17 MPa, whilst modern clay brick samples showed lower compressive strength value suitable for application of partition walls. The initial rate of water absorption increases with an increase of the soaking time, but tends to decrease after 90 min for both ancient and modern brick units. Superior performance in terms of thermal conductivity, thermal resistance and durability under fire action were observed for the ancient brick samples compared with modern clay brick and stone samples.