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Highlights • The wooden foundations of Ponte di Rialto were analysed in order to determine the tree species used for its construction and to examine the timber's present-day physical and mechanical properties. • The foundations underwent micro-morphological, physical, chemical and mechanical analyses. • The footings of the bridge's foundations, mostly consisting of alder wood, were shown to be in a good condition generally. • Two periods of construction were determined. The later dating corresponds to the construction of the stone bridge that still exists today, while the other period probably refers to the foundations of the initial Ponte della Moneta. Abstract The wooden foundations of Ponte di Rialto (Rialto Bridge), the oldest and most famous of the four bridges spanning the Grand Canal in Venice, Italy, were analysed in order to determine the tree species used to construct the foundation, to examine the timber's present-day physical and mechanical properties and to identify construction periods. The material recovered during geotechnical surveys underwent micro-morphological, physical, chemical and mechanical analyses. The radiocarbon method was used for dating purposes. The footings of the bridge's foundations, mostly consisting of alder wood, were shown to be in good overall condition generally. A comparison of normal and polarised light images of wooden cross-sections showed abundant crystalline cellulose within the cell walls, indicating that the state of conservation of the waterlogged samples is very close to that of sound alder wood. Only one alder sample showed signs of severe bacterial attack, mostly concentrated in the fibre cell walls. Radiocarbon dating identified two distinct construction periods. One sample dates to 1570 AD ± 85, whilst another dates to the year 960 AD ± 59. The later dating corresponds to the construction of the stone bridge that still exists today. The earlier period, around the year 1000, likely refers to the foundations of the first bridge, built after several pontoon bridges, and corresponding to the initial Ponte della Moneta. [ABSTRACT FROM AUTHOR]

This paper outlines the physical characterisation of findings of woods from the excavation of the Etruscan–Roman ancient harbour of Pisa. The physical characterisation deals with measurements of wood density, shrinkages and maximum water content. The measurements are performed with a methodology specifically set up for the archaeological wet material, not applicable as standardised international methodologies. Physical characterisation is necessary to measure the wood decay, through a useful decay index, and to define the consolidation strategies for the recovery of the wooden findings, for their conservation and enjoyment. Results confirm the high decay of wood samples, probably due to the almost complete loss of the cellulose fraction of the cell walls, shown by the very low basic density (average value less than 0.2 g/cm3) and the high water content (more than 500%). The parameter of the residual basic density seems less useful for the identification of the consolidation strategy. [Copyright &y& Elsevier]

• EDTA-2Na, EDTA-4Na and citric acid used to extract iron in oak wood (Quercus spp.). • ESEM, FT-IR and DMA used to characterise samples after the extraction treatments. • Alkaline agents have an impact on both chemical and viscoelastic characteristics. • Modification and loss of hemicelluloses increases the viscous behaviour of treated wood. • Results are generalizable to the various wood treatments where high pH is adopted. The process of extracting iron from waterlogged wood was simulated on non-degraded oak wood (Quercus spp.) with the aim of evaluating the effect of three levels of pH (acid / close to neutral / alkaline, obtained using three products normally used to extract iron) on both the composition and the viscoelastic mechanical properties of wood samples. The three products were disodium-ethylenediaminetetraacetic acid (EDTA-2Na), tetrasodium-EDTA (EDTA-4Na), and citric acid, and they were used at different concentrations and different extraction durations. Environmental Scanning Electron microscopy (ESEM) was used to observe the microstructure before and after extraction, ATR-FTIR was used to analyse the chemical composition and Dynamical Mechanical Analysis (DMA) was used to assess the storage and loss moduli and the loss factor of samples after treatment. Mass loss measurements after treatments were also carried out. The results indicated that chelating agents inducing alkaline conditions could have an impact on both chemical and viscoelastic characteristics of wood, whereas neutral or acidic conditions did not appreciably affect the considered characteristics. The observed effects are related to modifications of hemicelluloses composition (with partial mass loss of wood), which provoked a clear increase of the viscous behaviour of the treated material. These modifications were only limitedly and indirectly detectable using the other considered techniques. Being induced by the obtained alkaline conditions, present results are generalizable to the various treatments where high pH is adopted, and hence not only limited to the iron removal process. Thus, based on the knowledge attained in this research, conservators can be aware of the potential impact of these treatments on the wood structure, and this should help in gaining greater control over this process. [ABSTRACT FROM AUTHOR]

Thermogravimetry (TG) is used to measure the change of sample mass versus temperature or time under a program controlling temperature. It is a common thermal analysis tool with a precise built-in balance, and accurate data can be obtained through a small amount of sample at the level of milligrams. The feasibility of the TG method for determining maximum water content (MWC) measurement of waterlogged archaeological wood was studied. Simulated waterlogged wood and waterlogged archaeological wood were used to determine the test condition for the TG method. MWC data obtained through the oven-dry and TG methods with different mass gradients from 0–10 mg to >50 mg were analyzed statistically. Deviation, error bar, and coefficient of variation were evaluated. According to the results, when sample mass is no less than 30 mg, and holding time at 105°C is no less than 40 min, data deviation between these two methods is less than 5%. Effect of sampling depth and presence of inorganic deposits were also investigated. Specimens were taken from an archaeological wood with a sampling depth from 2 to 6 mm, then MWC was measured through the TG method. The results indicate MWC of the samples taken from a depth of 2–4 mm is higher than that taken from a depth of 0–2 mm and is lower than that taken from a depth of 4–6 mm, which is related to inorganic deposits. The presence of deposits was verified through SEM-EDX. MWC of three archaeological wood samples from China and five archaeological wood samples from Italy were measured to verify the effectiveness of the TG method when wood species and degradation degree are different. [ABSTRACT FROM AUTHOR]

Present work describes the application of NIR spectroscopy coupled with Partial least square (PLS) regression to estimate the residual chemical composition (in terms of holocellulose and lignin) of wood decayed by attack of biotic agents (such as bacteria) when preserved for a long-time in waterlogged conditions. The evaluations allowed assessing how various parameters may influence the predictive ability of calibration models. These parameters include: pre-processing manipulations (first and second derivatives curves, both normalized and not, were compared with baseline corrected spectra), the ranges used for model calibration, the preliminary conditioning of the samples (meals conditioned at both 22 °C/50% r.h. and 60 °C), and the way to take account of the presence of inorganic fillers permeating wood. To such aim, 59 samples from different excavations were considered, with samples belonging to several hardwoods and softwoods ( Alnus sp.p., Cupressus sempervirens , Larix decidua , Picea abies , Pinus sp.p., Quercus sp.p., Ulmus sp.p.), and to different states of preservation and burial environments. Values used for calibration were obtained by conventional wet analyses. Results showed that NIR spectroscopy coupled with PLS multivariate analysis could be used to reliably assess the residual chemical composition of waterlogged decayed wood provided that the calibration range is carefully selected and that original data are suitably pre-processed. However, the best models were different for the two considered components (lignin and holocellulose) and depending on which data set (softwoods or hardwoods) the samples belonged. Finally, it was also shown that the models predictive ability is affected by high ash content (too contaminated samples had to be excluded in order to attain good results). [ABSTRACT FROM AUTHOR]

This paper reports on the assessment of lignin and holocellulose by means of ATR-FTIR analysis and multivariate PLS regression. The analysis was conducted on 59 samples coming from different excavations where wood had been preserved in waterlogged conditions. A range of results from different wood species ( Alnus sp.p., Cupressus sempervirens , Larix decidua , Picea abies , Pinus sp.p., Quercus sp.p., Ulmus sp.p.), states of preservation, waterlogged environments, and burial times are presented. A calibration model was selected after comparing different reference data (samples extracted and not-extracted, and ash-rich and ash-free bases of calculation for the calibration values), and two different post-acquisition spectroscopic manipulations (both in terms of normalisation procedures and of spectral ranges used for the calibration). Results showed that the best models were different depending on which considered component (lignin or holocellulose) was measured and to which data set (softwood or hardwood) the samples belonged. It is shown that the predictive ability of the models is affected by high ash content (too contaminated samples had to be excluded in order to attain good results, because of excessive overlapping of bands related to the inorganic fraction) but not by the preliminary extraction of sample. Furthermore, the stability of best models is also demonstrated and a procedure of external validation carried out on an external set of samples confirmed the general validity of the identified models. [ABSTRACT FROM AUTHOR]