Durability assessment of the Alaçatı tuff (Izmir) in western Turkey

Abstract

Alacati tuff has been used extensively as a source of building stone for outdoor and indoor decorations since the historical times in and around the tourist town of Alacati (western Turkey). The use of the Alacati tuff in buildings has been made compulsory by the Alacati municipality, for preserving the historical appearance of the buildings, after 2005 in Alacati. It has been noticed that, evident deteriorations developed in tuff surfaces of the stone buildings and garden walls within 5–6 years of their emplacement. Durability properties of the Alacati tuff are evaluated by determining the mineralogical, chemical, and physico-mechanical properties of the fresh tuff samples obtained from the only operative quarry in the area. Ageing tests such as Na2SO4 and MgSO4 salt crystallization, freezing–thawing, and wetting–drying were conducted on the fresh tuff samples to assess their durability. Additionally, the durability of the tuff is also evaluated by determining its average pore diameter, saturation coefficient, wet-to-dry strength ratio, static rock and slake-durability indices. Fresh Alacati tuff has high porosity and low unit weight and strengths and are classified to be very poor to moderately durable stone based on the test results of different durability assessment methods. Mineralogical and geochemical analyses have also been carried out on the deteriorated tuff samples collected from the surfaces of the stone buildings to determine the effect of weathering on tuff and the test results have been compared with those of the fresh tuff samples. There is no major difference observed between the mineralogy and chemistry of the fresh and weathered tuff samples thus, it has been concluded that physical weathering has been dominant in the area in deterioration of tuff.