Salt weathering in the Al-Namrud Monuments in Iraq: characterization of historical stone

1. Salt weathering in the Al-Namrud Monuments in Iraq: characterization of historical stone and fresh stone treated with accelerated decay tests Ali H. E., Khattab S.A., Beck K., Al-Mukhtar M.

2. The site In the north of Iraq, beginning in the second millennium B.C., the Assyrian Empire developed great cities such as Nineveh, Korsabad, and Calah (Al-Namrud). Assyria imperial map

3. The site Al-Namrud city, is located in the north of Irak Al-Namrud city Bagdad

4. The site Al-Namrud, is located 37 km to the eastern south of Mosul city, Sampling Eski quarry Mosul Fresh stones samples Al-Namrud monuments Historical stone samples Bagdad The quarries of the stone elements (marble and limestone) which used in the construction of the monument were extracted from Eski-Mosul area.

5. The site AL-NAMRUD city and monuments Ancient city of Assyria: founded in the 13th century BC by Shalmaneser I At 9th century BC Ashurnasirpal II made it the capital of Assyria It was the site of a religious building founded in 798 BC by Queen Sammu-rema

6. The site AL-NAMRUD city and monuments The city was protected by an outer strong wall (8 km) built from limestone Entry of the city The outer wall fence of the locations was built with the limestone

7. The site Clayey brick wall Green marble Limestone The construction elements of the monument Construction materials: Clayey bricks - Limestone and marble • Outer wall built with limestone (8 km) • Others walls built with the clayey bricks, then coated with the green marble • 3. The ground covered with a limestone

8. The site In-situ observations: sever signs of damage of the building structure and stones of the city Al-Namrud monument stones suffered from many decay factors Rain and wetting drying factors, Freezing and thawing, salt effect, Acid effect from bird waste,……..

9. The study Studies carried out on the stones coming from Al-Namrud site and from the quarry Characterize the two stones: fresh stone – quarry and historical stone – Al-Namrud site Determine the effect of accelerated weathering tests on the fresh stone The aim of the preliminary study Verify the origin of the stone! Evaluate the degree of degradation understand the main reasons and mechanisms of the damages observed * Fresh samples in order to construct a database for the studies

10. Results Analysis X-Ray Diffraction analysis of historical limestone • RESULTS AND ANALYSIS • Characterization of the historic and fresh limestone XRD & TGA show similar mineralogical composition major mineralogical compositions calcite (CaCO3) about 93%and silica (SiO2)- Quartz X-Ray Diffraction analysis of fresh limestone This may reflect the correct selection of the quarry

11. Results Analysis • RESULTS AND ANALYSIS • Characterization of the historic and fresh limestone samples More amount of water fill the pore of the historical limestone More big pores in the historical limestone than in the fresh one!

12. Results Analysis • RESULTS AND ANALYSIS • Characterization of the historic and fresh limestone samples Incremental pore volume ml/g Mercury intrusion porosimetry: historical and fresh limestone showing cumulative pore volume & incremental pore volume Dissolution water transfer

13. Results Analysis • RESULTS AND ANALYSIS • Characterization of the historic and fresh limestone samples Properties of fresh and historic limestone

14. EXPERIMENTAL PROGRAM • Aging tests: wetting-drying decay test

15. Results Analysis dry wet ** Normalized Weight of samples = weight of the sample divided by its initial dry weight Decay tests: accelerated wetting – drying cycles Results of tests carried out with distilled water and with saline water (10% and 20% of NaCl) • The normalized wet and dry weights reduce with cycles. water absorption followed by insufficient drying temperature and duration • Changes in the weight is function of (% of salt): As % salt increases – changes in the NW reduces • Dissolution CaCO3 of limestone is very low (0.2 mg/L) but affect samples aged with distilled water. • & • Reduction in the absorption due to incomplete drying

16. Results Analysis Mercury intrusion porosimetry curves Curves of the altered stones are located between the two limit curves: fresh stone and historic stone with an increasing in the values of total porosity and the nature of pore structure toward the historic stone Incremental pore volume ml/g In-situ: many decay factors However, laboratory tests give preliminary indications about the mechanisms of degradation of this limestone. Water transfer- dissolution

17. Results Analysis Capillary - imbibition tests Increasing pore diameter as shown previously leads to decrease the Capillary front height The more reduction occurred in the samples submitted to wetting-drying process and especially with saline water. The effect of NaCl salt seems to accelerate the dissolution and hence increase the diameter of the pore giving a bigger range for precipitation

18. CONCLUSIONS Results show weathering effects on the historic stone in comparison to the fresh stone. The salt weathering seems to be the main factor of the physico-chemical reactions (dissolution, crystallization), structural, textural changes and deterioration in the Al-Namrud monuments In the field (In-situ), T° varies from -2°C to +50°C, numerous mechanisms contribute in the degradation of the monument: dissolution of carbonate, NaCl salt solubility, salt penetration in the pore space and mechanical, thermal and hydric behaviour mainly shrinkage and expansion inducing the fatigue of the stone. A lot of laboratory and field work must be carried out to firstly evaluate the state of the degradation of different stones and to determine a proper method to repair or/and to stabilize the degradation in order to insure the stability of the different structures of this very old city - Al-Namrud - constructed in the second millennium B.C. by the Assyrian Empire. Research started at the University of Mosul - Irak and continued in collaboration with our research centre in Orléans - France

19. Thank you for your attention