چكيده به لاتين
Concrete is widely used as a construction material. For reducing the environmental effects of concrete industry and improving the environmental sustainability, use of any Industrial waste in concrete to improve its mechanical and durability characteristics can lead to saving of energy and resources. In this reaserch the possibility of using a hydrophobic carbon powder produced from waste materials of chemical industries, as an admixture in concrete was investigated. Good dispersion of carbon powder in cementitious environment is a precondition for its efficient use, which is not easy due to its high hydrophobicity. So effect of cementitious environment and several different concrete admixtures was assesd on dispersion of carbon powder. However cementitious environment had negative effects on dispersion, use of superplastisizers specially poly carboxylate greatly improved dispersion in this environment. Effect of hydrophobic carbon powder on workability, compressive strentgh, porosity, water sorptivity and absorption, water desorption, electrical conductivity and hydrophobicity of cement paste and concrete cured for up to 28 days is investigated. Adding carbon powder,up to 15 percent by weight of cement to cement paste decreased the absorption, sorptivity and electrical conductivity by 23, 86 and 65 percent recpectively. In the case of concrete, adding up to 20 percent by weight of cement, carbon powder to the mix, decreased the sorptivity and electrical conductivity by 60 and 30 percent respectively. By assesing the water droplet contact angle on paste samples, it was seen that increasing carbon powder content lead to more hydrophobicity. In cement paste, adding carbon powder increased compressive strentgh due to deacrising its porosity, but in concrete it had no major effect. Using carbon powder in concrete leads to its hydrophobicity and therefor to deacrising water permeability and its durability. And in addition its importance is in that by using this subsidiary production of chemical material factories, we can help the environmental sustainability.