Development of eco-friendly composite materials for architectural structures

The effects of building materials both commercially and in terms of human and environmental health are very important in architectural applications. With the problem of climate change, new, high-quality composite materials are being developed along with technological developments to increase the resistance of structures against time and environmental effects. Thanks to nanotechnology and developments in the construction industry, various smart materials can be produced. In this way, building materials can be endowed with important properties such as self-renewal, antibacterial and hydrophilic-hydrophobic properties, increased strength and resistance to environmental effects. Hydroxyapatite (HA), a biocompatible material that stands out for itsuse in medicine and healthcare, is alsoused in applications such as water purification and photocatalytic coatings. Thanks to its superiorhydrophilic properties, HA is used as composite and coating in the production of building materials that are self-cleaning and resistant to stains and abrasions. Boron carbide (B4C) is an important nanomaterial that exhibits properties such as superior strength, wear resistance and photocatalyst activity. Composites were produced by forming homogeneous mixtures of different concentrations of boron carbide with hydroxyapatite, pressing them with the addition a binder and sintering them at various temperatures. In this way, it is aimed to develop and characterize new HA-B4C composites that do not harm human and environmental health and are resistant to environmental effects by providing long life time and biocompatibility properties to the structure. The physical, chemical and biological properties of the produced composite samples were observed with various analyses. Nanoscale pure HA was produced by the sol-gel chemical synthesis method, which is based on a reaction at the molecular level. Nanocomposite powders were produced by obtaining a homogeneous mixture of ground B4C powders with the sol-gel synthesized HA in solution environment by mechanical stirring. Composite powders were pressed and sintered at various temperatures (800 °C, 950 °C and 1100 °C) for different analyses. Composites produced as pure HA and 10% and 20% B4C added HA and sintered at various temperatures were characterized physically, chemically and biologically through various analysis. Mechanical properties of the samples are microhardness and compression test; morphological features scanning electron microscopy (SEM) imaging technique; contact angle measurement of hydrophilic-hydrophobic surface properties; Its chemical properties, X-ray diffraction analysis and EDX element analysis and biological antibacterial properties were tested by disc-diffusion method against two different bacterial species (Gram negative: Escherichia coli and Gram positive: Staphylococcus aureus). Research results showed that HA-B4C composites exhibited superior antibacterial activity with increasing B4C concentration than antibacterial drug control. HA-B4C composites have shown superhydrophilic properties and it is predicted that this will provide self-cleaning surface properties. It is thought that the new HA-B4C composites, which can be resistant to environmental effects and do not harm human and environmental health by providing long life and biocompatibility properties to the structures, can be integrated into various resins in powder form and serve the purpose of being used as a coating, as well as having the potential to be used as a composite structural element in new generation architectural structures and various other applications.