Microstructural investigation of innovative UHPC

The production of ultra high performance concrete (UHPC) with target streng ths greater than 200 MPa has recently been considered for specific structur al applications that need this enhanced mechanical performance. The main pu rpose of developing these innovative UHPC mixtures is to produce high-stren gth precast concrete elements with excellent durability to serve as both th e inner wedges and the outer barrel of a new nonmetallic anchorage system. The anchorage is for post-tensioning applications using carbon fibre-reinfo rced polymer tendons. The UHPC mixtures examined show very dense microstruc tures with some unique characteristics. The bond between the micro carbon f ibres and the cement paste seems to be very good and the cement paste obser ved in the vicinity of the fibres was shown to be very dense and homogeneou s. The micro carbon fibres seem to govern the strength and postcracking beh aviour of these materials. (C) 1999 Elsevier Science Ltd. All rights reserv ed.