Determination of mechanical properties of geopolymer based composites suitable for 3D additive manufacturing

The use of traditional concrete for many years until today has brought many problems. The production and use of Portland cement is the most responsible for the problem caused by conventional concrete. It is estimated that the use of concrete will continue to increase as the needs of humanity such as sheltering and transportation continue. The detrimental influence on the environment of Portland cement produced and used so far can be understood by the fact that it accounts for 6-8% of CO2 emissions. It is obvious that this effect will negatively affect our sustainable future. Therefore, it is necessary to eliminate the production of concrete that will meet the needs of humanity with novel, sustainable and "green" alternative binding materials. In addition to the environmental damage caused by concrete produced with Portland cement, the storage and recycling of construction and demolition waste in the world is another problem that humanity must deal with. About 1/3 of the total annual waste of the European Union is covered by construction and demolition waste. In developed European countries, most of this waste is reused, while in countries that do not have large economies, this rate is quite low. In addition, in European Union countries with large economy, the rate of production of value-added goods by the reuse of construction and demolition waste is very low. These materials are used in transportation projects such as road pavements and filling materials. Traditional production methods used in the construction industry are considered to be very slow, risky and costly in today's technology. Occupational accident risk is of great importance in traditional construction productions used until today. Mold and labor costs are another issue that needs to be optimized during the production stages. Therefore, researchers carried out studies focusing on innovative and sustainable ways in production methods. The aim of this thesis is to develop innovative, sustainable and "green" 3D printable geopolymer-based composites developed within the scope of the thesis, to minimize the harmful effect of cement production on the environment, to reuse construction and demolition waste with added value, and to expand automation by developing 3D production in the construction industry. In this context, the fresh/rheological properties of geopolymer binders suitable for 3D printing were determined. After that, the mixtures suitable for printing were produced by 3D additive manufacturing and their mechanical properties were determined. The anisotropic behavior and interlayer bond strength properties of the produced mixtures were determined as a result of curing at ambient conditions for 7, 28 and 90 days. As a result, it is believed that the produced geopolymer composites suitable for 3D additive manufacturing will bring sustainable solutions to many problems encountered in the construction industry, such as global warming, excess cost, occupational accidents and management of construction demolition wastes caused by CO2 emissions.