Presentation on theme: "Salt weathering in the Al-Namrud Monuments in Iraq:"— Presentation transcript:
1Salt weathering in the Al-Namrud Monuments in Iraq: characterization of historical stoneand fresh stone treated with accelerated decay testsAli H. E., Khattab S.A., Beck K., Al-Mukhtar M.
2ThesiteIn 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
3Al-Namrud city, is located in the north of Irak siteAl-Namrud city, is located in the north of IrakAl-Namrud cityBagdad
4Al-Namrud, is located 37 km to the eastern south of Mosul city, siteAl-Namrud, is located 37 km to the eastern south of Mosul city,SamplingEski quarryMosulFresh stones samplesAl-NamrudmonumentsHistorical stone samplesBagdadThe quarries of the stone elements (marble and limestone)which used in the construction of the monument wereextracted from Eski-Mosul area.
5The site AL-NAMRUD city and monuments Ancient city of Assyria: founded in the 13th century BC by Shalmaneser IAt 9th century BC Ashurnasirpal II made it the capital of AssyriaIt was the site of a religious building founded in 798 BC by Queen Sammu-remaThesite
6The outer wall fence of the locations was built with the limestone siteAL-NAMRUD city and monumentsThe city was protected by an outer strong wall (8 km) built from limestoneEntry of the cityThe outer wall fence of the locations was built with the limestone
7The construction elements of the monument siteThe construction elements of the monumentConstruction materials:Clayey bricks - Limestone and marbleClayey brick wallOuter wall built with limestone (8 km)Others walls built with the clayey bricks, then coated with the green marble3. The ground covered with a limestoneGreen marbleLimestone
8ThesiteIn-situ observations:sever signs of damage of the building structure and stones of the cityAl-Namrud monument stones suffered from many decay factorsRain and wetting drying factors, Freezing and thawing, salt effect, Acid effect from bird waste,……..
9Characterize the two stones: fresh stone – quarry and studyStudies carried out on the stones coming from Al-Namrud site and from the quarryCharacterize the two stones:fresh stone – quarryandhistorical stone – Al-Namrud siteDetermine the effect ofaccelerated weathering testson the fresh stoneThe aim of the preliminary studyVerify the originof the stone!Evaluate the degreeof degradationunderstand the mainreasons and mechanismsof the damages observed* Fresh samples in order to construct a database for the studies
10correct selection of the quarry ResultsAnalysisX-Ray Diffraction analysis of historical limestoneRESULTS AND ANALYSISCharacterization of the historic and fresh limestoneXRD & TGA show similar mineralogical compositionmajor mineralogical compositionscalcite (CaCO3) about 93% andsilica (SiO2)- QuartzX-Ray Diffraction analysis of fresh limestoneThis may reflect thecorrect selection of the quarry
11Characterization of the historic and fresh limestone samples ResultsAnalysisRESULTS AND ANALYSISCharacterization of the historic and fresh limestone samplesMore amount of water fill the pore of the historical limestoneMore big pores in the historical limestone than in the fresh one!
12Characterization of the historic and fresh limestone samples ResultsAnalysisRESULTS AND ANALYSISCharacterization of the historic and fresh limestone samplesIncremental pore volume ml/gMercury intrusion porosimetry: historical and fresh limestone showing cumulative pore volume & incremental pore volumeFresh limestonePorosity by mercury intrusion (%)21Total volume of pores0.11% of pores having > 6 µm25% of pores having < 6 µm75Average pore diameter (µm)0.28Historic limestone340.1965350.73Dissolution water transfer
13Properties of fresh and historic limestone ResultsAnalysisRESULTS AND ANALYSISCharacterization of the historic and fresh limestone samplesProperties of fresh and historic limestoneFresh limestoneBulk density (gm/ml)2.04Skeletal density (gm/ml)2.66Porosity by hydrostatic method (%)26Water content at saturation (%)13.5Porosity by mercury intrusion (%)21Historic limestone1.712.583823.834
14Aging tests: wetting-drying decay test EXPERIMENTAL PROGRAMAging tests: wetting-drying decay test
15Decay tests: accelerated wetting – drying cycles ResultsAnalysisDecay tests: accelerated wetting – drying cyclesdrywet** Normalized Weight of samples = weight of the sample divided by its initial dry weightResults of tests carried outwith distilled waterandwith saline water (10% and 20% of NaCl)The normalized wet and dry weights reduce with cycles. water absorption followed by insufficient drying temperature and durationChanges in the weight is function of (% of salt): As % salt increases – changes in the NW reducesDissolution 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
16Mercury intrusion porosimetry curves ResultsAnalysisMercury intrusion porosimetry curvesCurves of the altered stones are located between the two limit curves: fresh stone and historic stone withan increasing in the values of total porosity andthe nature of pore structure toward the historic stoneIncremental pore volume ml/gIn-situ: many decay factorsHowever, laboratory tests give preliminary indications about the mechanisms of degradation of this limestone.Water transfer- dissolution
17Capillary - imbibition tests ResultsAnalysisCapillary - imbibition testsIncreasing pore diameter as shown previously leads to decrease the Capillary front heightThe 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
18CONCLUSIONSResults 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 monumentsIn 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 outto firstly evaluate the state of the degradation of different stones andto determine a proper method to repair or/and to stabilize the degradationin 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