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A method for the analysis of the chemical composition of ancient mortars is proposed. The use of the hot hydrochloric acid attack in order to carry out a separation of the binder and the aggregate is discussed. Different types of mortars of Pamplona Cathedral are analyzed. Traditional chemical methods and atomic emission spectroscopy are employed. The mineralogical studies have been carried out using X-Ray Diffraction. Statistical methods are employed in order to establish a comparison between the different attacks.

Different ancient mortar samples of Pamplona's San Cernin church have been analyzed to characterize their binder and aggregate fractions. A complete characterization has been carried out including chemical (rapid approximate analysis, soluble salts and trace elements, using traditional chemical procedures, ionic chromatography and spectrophotometry techniques), mineralogical-petrographic (structural characterization and X-ray diffraction) and thermal studies (simultaneous differential thermal and thermogravimetric analysis). These studies have permitted to establish that a type of lime mortar with silica aggregate was employed in the building of the tower. Three different classes of this type of mortar and their approximate original composition have been determined. Recommendations about the employment of new materials in a possible restoration are given.

Ancient mortars used in the construction of the church of Santa María de Irache monastery have been studied. With the aim to characterise their binder and aggregate fractions, a complete characterisation has been carried out including chemical (rapid analysis, soluble salts and trace elements), mineralogical (structural characterisation and X-ray diffraction, XRD) and thermal studies (simultaneous differential thermal and thermogravimetric analysis, TGA-DTA). Lime binder, lime with dolomite phases and mixed mortars (lime and gypsum) have been determined. The approximate original composition of these classes of mortars have been presented. Advice about the employment of repair materials in a restoration are given. RésuméOn a étudié les mortiers employés à l'église du monastère de Santa María de Irache. On a réalisé une caractérisation complète à l'object de connaître le liant et l'agrégat, en utilisant l'analyse chimique (analyse rapide, sels solubles et éléments trace), l'analyse minéralogique Material and methodsThe sampling procedure for mortars has been carried out taking a part of the mortars with a chisel and throwing away the external portion of the joints, with the aim of obtaining nonaltered material.A total of 51 mortar samples were studied, belonging to different areas (Gospel lateral nave:MA, MB and MC zones of sampling; dome area: zone C; Epistle lateral nave: E, EI, EE and 3 ED zones; portico area: zone P) (Fig. 1). At least three samples of each architectural zone were taken to assure representative results.X-ray diffraction analysis was undertaken using a Bruker D8 Advance diffractometer (Karlsruhe, Germany), according to the diffraction powder method, with a CuK 1 radiation and 0.02 increment and 1 s/step, sweep 2 to 90, 2.The complete sample (binder and aggregate) ground in an agate mortar is dried until constant weight in a heater at 105ºC and then 1g of sample is taken for its subsequent analysis. The rapid approximate chemical study was carried out after attack with hot HCl 1:5 volume ratio (2 M) [4], followed by a titration with ethylenediaminetetraacetic acid (EDTA) (using murexide and eBT (eriochrome black T) as indicators) in order to determine calcium and magnesium concentrations. To establish the CO 2 content, a calcimeter was used. The chemical analysis of the main components in the complete samples was carried out after an alkaline fusion followed by traditional chemical methods [6][7]: calcium and magnesium contents as previously mentioned; sodium and potassium levels were determined by flame