Doug Hooton

Ground Granulated Blast-Furnace Slag

Since the discovery of the latent hydraulic reactivity of ground granulated blast-furnace slag (ggbfs) by Emil Langen at the end of the 19th century, this material has been used successfully as cement and concrete addition. This chapter includes all relevant information about this valuable material—from production and processing to the effect, which ggbfs additions have on the concrete performance. In this context, light is shed on decisive performance parameters of ggbfs. Of special interest nowadays is certainly also the information given about trace element contents in ggbfs and their leachability. Here and throughout the entire chapter, the latest insights from research and development work are included. Last but not least, the chapter contains very practical information when it comes to the use of ggbfs in concrete, including insights on rheological effects, concrete color and “greening”, and adequate curing. Moreover, an overview about relevant norms and standards on ggbfs as concrete addition is given.

Testing System for Mechanical Behaviors Analysis and Cracking Resistance of Concrete at Early Age

A uniaxial experimental set-up was developed to evaluate the self-induced stresses, visco-elastic strains and cracking potential of concrete from the time of its placement. The totally restrained condition is achieved by keeping the length change within a threshold of 3μm. The temperature rise of the specimens can be controlled within 1.5, by which the deformation because of temperature change due to cement hydration could be prevented. The tensile force required to compensate the shrinkage could be monitored and elastic strain and tensile creep can be calibrated without an obvious interference of temperature deformation. The preliminary results testified the workability of the system.