Microstructural investigation of innovative UHPC

The production of ultra high performance concrete (UHPC) with target strengths greater than 200 MPa has recently been considered for specific structural applications that need this enhanced mechanical performance. The main purpose of developing these innovative UHPC mixtures is to produce high-strength precast concrete elements with excellent durability to serve as both the inner wedges and the outer barrel of a new nonmetallic anchorage system. The anchorage is for post-tensioning applications using carbon fibre-reinforced polymer tendons. The UHPC mixtures examined show very dense microstructures with some unique characteristics. The bond between the micro carbon fibres and the cement paste seems to be very good and the cement paste observed in the vicinity of the fibres was shown to be very dense and homogeneous. The micro carbon fibres seem to govern the strength and postcracking behaviour of these materials. (C) 1999 Elsevier Science Ltd. All rights reserved.