Mechanical behavior of confined reactive powder concretes: Fid-Bau Portal

Mechanical behavior of confined reactive powder concretes

Dallaire, E. / Bonneau, O. / Lachemi, M. / Aitcin, P.C.

Reactive Powder Concrete (RPC) is a new type of very high strength concrete made from powders. With a very simple and inexpensive thermal treatment, a 200-MPa compressive strength can be achieved when using steel microfibers. Moreover, the use of steel microfibers makes RPC a pseudo ductile material but at a high unit cost. Better ductility can be obtained in a simpler and much less expensive way by confining a non fiber RPC in thin tubes. In this case, non fiber confined RPC can reach a 350-MPa compressive strength. The results of experimental tests regarding the behavior of confined plain or confined fiber reinforced RPC are summarized and discussed in this paper. Twelve columns were made to study the behaviour of confined RPC and plain RPC). The steel tubes had a thickness of 1.5 mm or 3.0 mm. In some of the tubes, th concrete was pressed during the first 24 hours in order to observe how effective the pressing of the confined RPc at early-stage is at increasing RPC compressive performance. When compressing a RPC before and after setting, most of the entrapped air is eliminated, as most of the early chemical shrinkage. All the tests were done using a MTS testing machinee with a 5000 kN capacity. The longitudinal strain of the concrete cores was measured by Linear Velocity Displacement Transducers placed around the columns. Stress-strain curves for all test pieces were obtained. Confining RPc is more efficient than using steel microfibers in order to improve the ductility of this material. The high cost of the steel microfibers, which is the major factor influencing the price of the RPC, is no longer a problem since the confinement can be an attractive alternative to fiber reinforced RPC not only from a mechanical point of view, but also from an economical one.