Petr Martinec

Investigation of the microstructure and mineralogical composition of urinary calculi fragments by synchrotron radiation X-ray microtomography: a feasibility study

The outcomes from the feasibility study on utilization of synchrotron radiation X-ray microtomography (SR-μCT) to investigate the texture and the quantitative mineralogical composition of selected calcium oxalate-based urinary calculi fragments are presented. The comparison of the results obtained by SR-μCT analysis with those derived from current standard analytical approaches is provided. SR-μCT is proved as a potential effective technique for determination of texture, 3D microstructure, and composition of kidney stones.

Mössbauer Study of the Thermal Behaviour of Garnets Used in High-Energy Water Jet Technologies

A high-energy water jet combined with silicate garnets as abrasives has been proven to be a powerful tool for disintegration of hard materials. Thermal heating of the garnets is one way for structure improvement of the abrasive material. Room-temperature Mossbauer spectra of initial powdered almandine samples are characterised by one doublet corresponding to Fe2+ in dodecahedral position 24c. Almandine garnet, industrial product Barton HP 80 as reference material in all experiments, has a second doublet corresponding to Fe3+ in octahedral position 16a. In room-temperature spectra of heated almandine garnet samples from locality Ktis and Měděnec (heated under temperatures 200–1000°C by 100 degrees for 1 hour in air) a new doublet originating from γ-Fe2O3 nanoparticles appeared. Under a heating temperature of higher than 800°C, the broad sextets of α-Fe2O3 and e-Fe2O3 in spectra were discovered. No additional doublets or sextets appeared in room-temperature Mossbauer spectra of reference material of almandine garnet Barton HP 80 heated under each temperature.

Granodiorite aggregates from East Bohemia for high-performance and high-strength concretes

This paper describes the petrological characteristics of biotite granodiorites from the Litice nad Orlici Quarry in East Bohemia (Czech Republic). Physical, chemical and mechanical parameters of extracted rocks and crushed aggregates are presented, together with the results of a study of rock fabric influence on the shape parameters of aggregate grains as a principal component of high-performance and high-strength concretes.

Composition and Microstructure of Plasters in Convent of the Želiv Monastery (Czech Republic)

The paper deals with analyses of composition and structure of historic plasters from the convent building of the Želiv Monastery (Czech Republic). Composition and microstructure of plaster samples taken from the historic object have been assessed using both traditional and advanced analytical methods. The following techniques have been used for the assessment of binders and fine aggregates in plasters: optical microscopy of thin sections, mineralogical and petrographic analysis of separated components, infrared spectroscopy, and thermal analysis. Presented results show significant differences in character of the studied materials of varying age and demonstrate the effectiveness of the taken analytical approach.