The effect of natural resin applied to gypsum-stabilized rammed earth surface on water resistance

Earth material has numerous advantageous aspects such as providing structural comfort conditions without the need for additional layers as in reinforced concrete, having low cost, using less energy in production and use, being recyclable, being harmless to human health and the environment, and being ecological. However, it also has negative aspects such as weak compressive strength, sensitivity to water, causing space loss with thick walls, requiring labor and time. Studies conducted at ITU since 1980 have contributed to the development of alker building material, which has improved in many aspects such as water resistance, compressive strength, and rapid production of earth building material. Additives incorporated into the content of the earth mixture have yielded positive results in increasing water resistance. The contribution of the coating to be applied to the surface of alker to the protection of the material against water remains a topic lacking in the literature. It is important for the material to be applied to the surface to be environmentally friendly and sustainable in order to improve the quality of sustainable earth building material. Natural resins increase biological resistance by reducing water intake on the applied surface thanks to their water-repellent properties. In the study, it was investigated whether the application of natural resin to the surface of gypsum-modified rammed earth, known to have high water resistance compared to adobe, would further affect its water resistance. The earth mixture prepared according to the alker recipe was compressed in 6 steel molds with dimensions of 15 cm x 15 cm x 15 cm. Water absorption tests were performed on 3 resin-coated and 3 resin-free alker samples. The results of the study indicate that the application of natural resin to the surface of gypsum-modified rammed earth reduces water absorption and increases resistance to water, while also preserving the natural appearance of the material by forming a transparent and permeable layer. It has been concluded that natural resin is an effective alternative for increasing water resistance of alker material.