5 - Optimization of production parameters of alkali-activated concrete

Abstract

Concrete is a frequently preferred construction material which is used in many fields and applications such as buildings, roads, tunnels, bridges, dams and harbors. Portland cement (PC), the main component of concrete, is a leading building material all over the world with an annual production capacity of 4 billion tons and a growth rate of 4%. About 7% of total CO2 emissions originate from production of PC. It is predicted that 17% of total CO2 emissions will come from PC production in the next few years. Scientists have been making effort to overcome environmental and economic problems caused from PC production. Alkali-activated binders (AABs) emerging as a result of these efforts were originally proposed by French researcher Davidovits for aluminosilicate-based inorganic polymers. AABs are semicrystalline three-dimensional polymers synthesized by activation of high alkali solution with raw material rich in silicon and aluminum. Alkali-activated concrete (AAC) has been applied in various applications such as ready mixed concrete, reinforced concrete, concrete pipes, lightweight concrete. While most of the studies have focused on the reaction mechanisms and microstructures of AABs, relatively few studies have been carried out on the mix designs of AAC. However, engineering properties of AABs depend on raw materials, alkali activator type and alkali activator content, curing parameters, water content and mixing parameters. The aim of this chapter is to comparatively asses the production parameters of AACs in order to provide an understanding of the current findings and develop a general guideline.