Preparation and characterization of porous and stable sodium- and potassium-based alkali activated material (AAM)

Abstract The aim of this work is to produce highly porous and stable alkali-activated material (AAM) prepared from two combinations of sodium (Na)- and potassium (K)-based alkali solutions (NaOH/Na₂SiO₃ and KOH/K₂SiO₃). The reactive metakaolin as precursor and AAM were characterized using X-ray diffraction spectroscopy (XRD), X-ray fluorescence spectroscopy (XRF), aluminum nuclear magnetic resonance spectroscopy (27Al MS-NMR), diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), field emission scanning electron microscopy (FESEM), compressive strength measurement and Brunauer–Emmett–Teller (BET) surface analysis. The porosity of the AAMs were increased by using hydrogen peroxide and sodium percarbonate as foaming agents. Characterization results showed the viscosity of the K-AAM paste was 70% lower than that of the Na-AAM paste. However, the volume of the Na-AAM paste in an air-tight plastic tube was three times higher than that of K-AAM, but the specific surface area (SSA) of K-AAM were 30% higher than those of Na-AAM. In terms of compressive strength, the blank AAM (foaming agent-free) demonstrated the highest strength values: 6.1 MPa for K-AAM and 9.0 MPa for Na-AAM. When the concentration of the foaming agent was increased, the compressive strength of both the materials decreased but were still around 1.0 MPa. The FESEM images of the Na-AAM and K-AAM produced with H₂O₂ indicated the high porosity of materials which were also observed in SSA values of AAM. Furthermore, the XRD data showed that the Na-AAM contained water in hydrate form (halloysite) compared with the K-AAM, suggesting the different polymerization reaction route and speed between these AAM

Social-, health care and rehabilitation educators’ competence : a cross-sectional study

An educator’s competence influences the implementation of evidence-based education and the overall quality of social and health care. This study aimed to identify distinct competence profiles from Finnish social, health and rehabilitative care educators, as well as describe which personal and professional characteristics influenced belonging to a certain profile. Data were collected from 28 educational organizations located throughout Finland using the Health and Social Care Educators’ Competence instrument. The survey was answered by 422 educators. The performed K-means cluster analysis identified three distinct educator competence profiles, which differed in terms of self-assessed expertise in various competence areas and certain background characteristics. The results highlight that educational institutions should concentrate on refining the digital competence of educators, which requires networking, collaboration, and work-related pedagogical competence. The differences in evaluation identified for the three profiles demonstrates that more experienced educators should mentor their less experienced counterparts to ensure a high quality of education.peerReviewe