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1 Salt weathering in the Al-Namrud Monuments in Iraq: characterization of historical stone and fresh stone treated with accelerated decay tests Al-Mukhtar.

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Presentation on theme: "1 Salt weathering in the Al-Namrud Monuments in Iraq: characterization of historical stone and fresh stone treated with accelerated decay tests Al-Mukhtar."— Presentation transcript:

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

2 2 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 The site

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

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

5 5 AL-NAMRUD city and monuments 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 The site

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

7 7 Limestone The construction elements of the monument Construction materials: Clayey bricks - Limestone and marble 1.Outer wall built with limestone (8 km) 2.Others walls built with the clayey bricks, then coated with the green marble 3. The ground covered with a limestone Green marble Clayey brick wall The site

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

9 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 10 fresh X-Ray Diffraction analysis of fresh limestone historical X-Ray Diffraction analysis of historical limestone major mineralogical compositions calcite (CaCO3) about 93% and silica (SiO2)- Quartz XRD & TGA show similar mineralogical composition Results Analysis RESULTS AND ANALYSIS Characterization of the historic and fresh limestone This may reflect the correct selection of the quarry

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

12 12 RESULTS AND ANALYSIS Characterization of the historic and fresh limestone samples Mercury intrusion porosimetry: historical and fresh limestone showing cumulative pore volume & incremental pore volume Fresh limestone Porosity by mercury intrusion (%) 21 Total volume of pores 0.11 % of pores having > 6 µm 25 % of pores having < 6 µm 75 Average pore diameter (µm) 0.28 Historic limestone 34 0.19 65 35 0.73 Results Analysis Dissolution water transfer Incremental pore volume ml/g

13 13 Properties of fresh and historic limestone Fresh limestone Bulk density (gm/ml)2.04 Skeletal density (gm/ml)2.66 Porosity by hydrostatic method (%)26 Water content at saturation (%)13.5 Porosity by mercury intrusion (%)21 Historic limestone 1.71 2.58 38 23.8 34 RESULTS AND ANALYSIS Characterization of the historic and fresh limestone samples Results Analysis

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

15 15 Results of tests carried out with distilled water and with saline water (10% and 20% of NaCl) Decay tests: accelerated wetting – drying cycles 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 Results Analysis dry wet ** Normalized Weight of samples = weight of the sample divided by its initial dry weight

16 16 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 In-situ: many decay factors However, laboratory tests give preliminary indications about the mechanisms of degradation of this limestone. Water transfer- dissolution Results Analysis Mercury intrusion porosimetry curves Incremental pore volume ml/g

17 17 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 Results Analysis Capillary - imbibition tests

18 18 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 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 CONCLUSIONS 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.

19 19 Thank you for your attention


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