Background and aims. The ultimate goal of endodontic therapy is to prevent periradicular disease or to promote the healing of the periradicular lesions. The use of nontoxic, biocompatible, and bioactive materials designed for root canal obturation is preferred due to their increased potential to induce healing and bone regeneration, thereby restoring the functionality of the tooth and the adjacent tissues. The aim of this study was to analyze the biomineralization ability of an experimental endodontic sealer based on synthesized nanoparticles of calcium silicates. Methods. Six plastic moulds were filled with the freshly prepared experimental endodontic sealer and kept for 3 days at room temperature in a moist environment. After hardening, four samples were subsequently immersed in simulated body fluid (SBF) and introduced in incubator at 37o C and 100% relative humidity; two of them were kept for 7 days and the other two for 14 days. Two samples were not immersed in SBF and were used for comparison. The biomineralization potential was assessed by XRPD, SEM and EDS analysis. Results. Following immersion in SBF, XRPD analysis identified apatite crystals for experimental material both after 7 and 14 days. SEM images displayed the specific microstructure for bioceramic materials alongside with the presence of apatite crystals on their surface. EDS identified the presence of phosphorus and calcium elements, underlining the biomineralization potential of the experimental material. Conclusion. Interaction between experimental material and SBF succeeded in inducing precipitation of apatite on its surface, evidenced by XRDP, SEM and EDS analysis.

Concrete is a heterogeneous material, one of the most widely used materials on the planet, and a major consumer of natural resources. Its carbon emissions are largely due to the extensive use of cement in its composition, which contributes to 7% of global CO₂ emissions. Extraction and processing of aggregates is another source of CO₂ emissions. Many countries have succeeded in moving from a linear economy to a circular economy by partially or fully replacing non-renewable natural materials with alternatives from waste recycling. One such alternative consists of partially replacing cement with supplementary cementitious materials (SCMs) in concrete mixes. Thus, this work is based on the experimental investigation of the fresh and hardened properties of road concrete in which crushed river aggregates were replaced with recycled waste aggregates of uncontaminated concrete. At the same time, partial replacement of cement with a SCM material in the form of glass powder improved the durability characteristics of this sustainable concrete. The microstructure and compositional features of the selected optimum mix have also been investigated using polarized light optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction by the Powder method (PXRD) for the qualitative analysis of crystalline constitutive materials.

This study investigates the usability of the cathode ray tube (CRT) glass waste in a binder system. The raw materials – glass waste, river sand and cement were characterised. CRT waste was added in the amount of 30, 40 to 50 weight percent, as replacement for river sand. Glass chemical composition shows a high content in lead and alkaline oxides. Mortar prisms were prepared and kept under humid conditions. The mechanical properties were studied after 7, 28 and 90 days respectively. SEM with additional EDS was used in order to investigate the microstructure of the samples. All the samples containing glass waste achieved higher compressive strength than the control mortar. After 14, 28 and 42 days of maintaining the mortar in water no evidence of Pb was detected in the solutions.

Marin ILIEȘ, Nicolae HAR, Nicolaie HODOR, Dorina Camelia ILIEȘ, Tudor CACIORA, Ștefan BAIAS, Farida AKIYANOVA & Zharas BERDENOV - DEGRADATION AND GEOMYCOLOGICAL ASPECTS REGARDING THE NATURAL STONE FROM BUILT OUTDOOR, Carpathian Journal of Earth and Environmental Sciences, August 2021, Vol. 16, No. 2, p. 391 – 402; DOI:10.26471/cjees/2021/016/184