Abstract
Nowadays pozzolans are used vastly in civil projects. Pozzolan is a natural or artificial material containing active silica that increase the strength and improves some properties of concrete. In this survey for investigating some important properties of concrete, silica fume and fly ash was used in replacement of cement in different weights. Concrete compositions were made with water-cement ratio of 0.45 and cured under the same conditions. The main focus of this survey is to investigate the individual and combined effect of using Pozzolan on mechanical properties, permeability and shrinkage of concrete. The mechanical properties of concrete in compressive and bending strength at the age of 7, 28 and 90 days, were evaluated. Permeability was investigated with the water absorption test. The drying shrinkage of concrete was monitored for 90 days. Scanning Electron Microscopy (SEM) images was used in concrete cement based matrix morphology. The results showed that the addition of pozzolan increases the mechanical strength and reduce permeability and increase the drying shrinkage in some mixtures.
Highlights
Energy crises and the need to save the energy-making materials in producing productions like cement has caused to make a full-scale effort in producing economically and improving the quality in global scale
The results showed that the addition of pozzolan increases the mechanical strength and reduce permeability and increase the drying shrinkage in some mixtures
In samples containing fly ash with cement, compressive strength in comparison with control mix design is not increased at the age of 7 and 28 day
Summary
Energy crises and the need to save the energy-making materials in producing productions like cement has caused to make a full-scale effort in producing economically and improving the quality in global scale. Bhanja and Sengupta investigated the effect of silica fume on concrete tensile strength, different water-cement ratio (0.26 to 0.42) as well as replacement of silica fume with cement at different levels (0 to 30%) were considered[10] Their results showed that the presence of silica fume in the mixture caused a significant increase in tensile and compression strength. According to investigations of .Jianyong and Yan on three different kinds of concrete containing silica fume and slag individually and combinationally, with water-cement ratio of 0.26, it was shown that drying shrinkage at early ages was the same [17]. The investigation on some of the important properties of concrete containing silica fume and fly ash as a cement materials replacement in different quantities were discussed. The results showed that the addition of pozzolan increases the mechanical strength and reduce permeability and increase the drying shrinkage in some mixtures
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