Reactive powder concrete : workability aspects

Abstract

The ultra high performance characteristics achieved internationally through experimentation in Reactive Powder Concrete (RPC), intrigued the author to focus this study on this relatively new material, which in the knowledge of the author, has never been neither researched, nor tested locally. Following an extensive literature review, the author concluded that the exceptional properties of RPC in terms of mechanical strength and durability, are mainly achieved through the very low water to binder ratio, together with a very accurate and specific choice of materials. These factors inevitably give rise to problems with respect to the producibility and the workability of such mixes. The main objective of this dissertation was therefore to produce RPC locally and to study the variation of workability versus strength and durability. Following an extensive search for materials with similar characteristics as those specified by the developers of RPC namely, the Bouygues' Laboratory (France), the author performed a number of laboratory investigations. These confirmed the exceptional mechanical strength (compressive, tensile splitting, and flexural) and durability of RPC. As expected, such properties increased with a lower water to binder ratio, which therefore also resulted in a decrease in workability. This study has been crucial in identifying one of the fundamental aspects of the production of RPC, which consists of a prolonged mixing time using a powerful pan mixer. It also revealed that the differences in the materials used with respect to those specified by the developers of RPC, as well as the equipment available locally, had a direct consequence on the producibility, the workability and the ultimate performance of the mixes produced. Apart from reaching the main objective, this study serves as a useful background to further research on RPC locally.