The influence of the water saturation on the strength of volcanic tuffs used as building stones

Moisture content is one of the most important factors influencing the strength of building stones. Ayazini and Seydiler (Afyonkarahisar, Turkey) tuffs were investigated with the goal to determine the influence of the water on their strength. Mercury porosimetry was used to determine the pore-size distribution. Ayazini tuffs have pore sizes ranging from about 200,000 to 10 nm and Seydiler tuffs ranging from about 7000 to 10 nm. The tuff samples are immersed in water with different time periods of 1, 6, 24 and 48 h. The following physico-mechanical properties were measured for all the samples both in dry and saturated condition: compressive strength and flexural strength. Test results were indicated by simple regression analysis; good correlations were found between physico-mechanical properties with dry and saturated tuff samples. The results had shown their mechanical strength decreases in wet conditions for dry samples tested had 22.21 MPa uniaxial compression strength while 1 h immersed samples had 15.11 MPa, which indicates a decrease of 31.96 %. After the 48 h water immersion time period, the value of compression strength decreases by 43.99 % and becomes 12.44 MPa.