عنوان مقاله [English]
Permeability is an index to express the easiness of fluid movement in a porous body like concrete. Water containing deleterious substances like chloride ions, sulfate ions, aggressive chemicals and etc. can penetrate concrete and subsequently effect its short-term and long-term durability. So it is of great interest to study the water permeability of concrete. As permeability of concrete structures is one of the important effective parameters of their durability and service life, the effect of 5, 10, 15 and 20 mass percentages of silica fume, fly ash, zeolite and limestone powder that replace type II Portland cement was investigated on the permeability of 7-day concrete samples using cylindrical chamber method which was devised and developed in 2011 by Naderi. Permeability coefficient and diffusion coefficient, calculated based on cylindrical chamber test results and a one-dimensional model were used as indices to evaluate the permeability of the samples. Volume of the permeable voids percentage was also measured based on ASTM C642-06. The results show that silica fume increases the compressive strength and fly ash, zeolite and limestone powder decrease the compressive strength of the samples with respect to the control sample. Also, permeability and diffusion coefficients of the samples made of all mass values of these admixtures, except for limestone with a mass replacement percentage equals to 20 percentage, decreased with respect to the control sample. The relation between permeability and diffusion coefficients with permeability parameters was also investigated using a regression approach. It was also concluded that the relation between the dimensionless coefficients of permeability and diffusion and dimensionless coefficient of the test results (penetration depth, water penetration volume, average water flow rate and volume of permeable voids percentage) are estimated with a high accuracy using the approximation functions, but no equation can be found to estimate the relation between dimensionless coefficient of permeability and diffusion and compressive strength of the samples.