The Potential of Higher Share of Fly Ash as Cement Replacement in the Concrete Pavement

The world faces a number of environmental issues. Developments especially technological) in our society are still of highly extensive nature and the forthcoming process of globalization significantly affects the state of the environment. There is also a slight increase in population, uncontrolled extraction of raw materials for production of materials, energy and urbanization of the environment. At the same time the amount of harmful emissions and wastes increase. Mineral resources are considerably limited. As well as limited resources to feed a growing population (problems of drinking water and food) limited resources and materials needed for construction of buildings; infrastructure development and industry provision to further ensure the welfare of people. It follows the need for change of approach in area of civil engineering. Concrete is the most used building material in the world, but unfortunately it also leaves a major carbon dioxide emission. In building industry, it includes cutting back carbon dioxide emissions by using less energy consumptive materials - that is, by maximizing use of waste products. Many articles have been written on how this industry can contribute. This can occur in a number of ways and one of them is use substitutes for Portland cement with waste products such as fly ash, ground-granulated blast furnace slag cement, rice hull ash, silica fume, pozzolans of all types, and ground limestone, in the process of concrete production. This paper is focused on the possibility of using fly ash to replace cement in concrete pavement. Mechanical properties, chemical resistance, freezing and thawing of fly ash concrete were measured and compared with the reference specimen (C 30/37), which met the requirements of STN 73 6123. Besides, the economic assessment of costs of both concretes (with/without fly ash) was made. Finally, environmental benefits of brown coal fly ash utilization in the area of Slovak road engineering based on its life cycle analysis are also presented. (C) 2013 The Authors. Published by Elsevier Ltd.