In this study, boron-doped poly(vinyl) alcohol/HfO₂ nanofibers were prepared by electrospinning using PVA as a precursor. The effect of boron doping was investigated in terms of solution properties, morphological changes and thermal characteristics. Nanofiber mats were calcined first at 800°C. Then, the calcined products were pelleted and sintered at a rate of 8°C/min and remained 2 h at 850°C at atmospheric conditions to produce ultrafine ceramic nanocrystalline powders. The fibers and nanocrystalline powders were characterized by FT-IR, XPS, XRD and SEM. The addition of boron did not only increase the thermal stability of the fibers, but also their diameters, which yielded stronger fibers. The addition of boron did not only increase the thermal stability of the fibers, but also their diameters, which yielded stronger fibers.

The porous nature of lightweight expanded clay aggregate (LECA) is decisive in the physical and mechanical properties of concrete. A comprehensive experimental study consisting of 13 different mixtures and 234 specimens was carried out on density, absorption capacity, porosity, compressive strength, splitting tensile strength, modulus of elasticity, and the effect of moisture state of LECA concrete. Dry compressive strengths of mixtures were found to be between 18–38 MPa, and 9% higher on average than moist compressive strength. Modulus of elasticity values decreased significantly when specimens were oven-dried, where the decrease was 26% on average. The study also includes an evaluation of modulus of elasticity prediction models. All prediction models consistently overestimated dry modulus of elasticity, which is problematic for structural applications of LECA concrete. A unique model for modulus of elasticity prediction was developed as part of the study and verified using independent data from literature for its accuracy.

The construction industry is responsible for a significant share of global material consumption, including natural resources. Therefore, the United Nations Sustainable Development Goal 12.2 on sustainable management and efficient use of natural resources cannot be achieved without significant advances and contributions from the construction sector. Furthermore, various materials used by the construction industry contribute to the development and expansion of the LEED (Leadership in Energy and Environmental Design) system. LECA (Light Expanded Clay Aggregate) is one such material that enhances LEED performance through its key benefits, including lightness, thermal insulation, sound insulation, and fire resistance. One of the most effective methods for reducing the weight of concrete is the incorporation of lightweight aggregates, and the advantages of LECA include lessening loads and enabling reduced cross-sections, directly improving the sustainability of the built environment via reduced materials consumption. This study aims to develop a prediction model for the compressive strength of LECA-incorporated concrete through a meta-analysis. More than 140 data points were compiled through literature via 15 separate studies, and results were analyzed to conduct the meta-analysis. Moreover, an experimental program was carried out to verify the model and evaluate its accuracy in predicting compressive strength. Results from the developed model and the experimental program were in accordance with concrete having lower compressive strengths compared to those at high strength values. Likewise, more accurate results were obtained for concrete mixes that have w/b ratios of 0.5 or higher. Concrete mixes that have higher amounts of LECA by volume of concrete yielded more accurate results when using the prediction model. A sensitivity analysis was carried out to quantify the impact of several parameters on the compressive strength of LECA concrete.