Optimizing the tensile strength of concrete containing coal waste considering the cost

Abstract

Nowadays, removal of the waste from industrial activities is one of the serious problems in the world. Contrarily, needing the development of industrial construction and reduce its costs, with considering the construction quality, are the main priorities of progress. Therefore, in this paper, for the first time, all these issues are considered related to using the waste of coal extraction; also, the application of coal wash rejects in the concrete manufacture and its impact on tensile strength of concrete have been investigated. To this goal, coal waste was prepared from the Central Alborz Coal Preparation Plant in northern Iran. Designing the experiments by the response surface methodology (RSM), the influence of parameters like water/cement (0.4–0.6), cement content (305–445 kg/m3), aggregate volume (0.4–0.6%) and coal waste (0.5–9.75%) on the tensile strength to cost of concrete construction were evaluated. Presenting the model, optimizing and investigating the individual, reciprocal and simultaneous effects of independent variables on the tensile strength to cost of concrete by RSM were conducted for the first time. Based on the results of tensile strength tests and estimating the cost of concrete construction, the highest ratio of tensile strength to cost was obtained by using the cement content of 340 kg/m3, water/cement of 0.45, gravel volume of 0.55% and coal waste of 7.5%. In this case, the response value was 1.29E−6 MPa/USD. These results indicate the high potential of these wastes in the production of concrete in terms of tensile strength and also economic aspect.