The Effect of Taftan Natural Pumice Powder and Condensed Silica Fume on the Mechanical Properties and Durability of Concrete

Portland cement production has caused problems such as air pollution, energy consumption, loss of natural resources, exacerbation of greenhouse effects and global warming which have some economic issues. The use of pozzolans in the production of concrete decrease the negative points of the above mentioned problems and improves the mechanical properties and durability of the concrete in long run. In this paper, the effects of Taftan natural pumice powder and silica fume are investigated on the mechanical and durability properties of concrete. For this purpose, 18 concrete mixes were considered for two water to cementitious materials ratios of 0.4 and 0.45. Taftan natural pumice was replaced for Portland cement at 0, 10 and 20 percents and silica fume at 0, 7 and 10 percents. The results showed that using Taftan natural pumice improves the mechanical and durability properties of concrete. After 90 days the highest values of compressive strength, tensile strengths and sulfate resistance of mixes containing 10% Taftan natural pumice, 10% silica fume and mixes containing 20% Taftan natural pumice, 10% silica fume were achieved. For these mixes the capillary absorption and electrical resistance results were better comparing to the other mixes, too. On the other hand, the use of the Taftan natural pumice instead of a percentage of Portland cement has reduced the cost of production concrete.