Mechanical and thermal evaluation of Ultra High Performance Fiber Reinforced Concretes for engineering applications

Ultra High Performance Fiber Reinforced Concrete (UHPFRC) is a cement-based material, which behaves like a low-porosity ceramic material with excellent mechanical performance. This work was aimed to study soft cast (flowable at casting time) UHPFRC s and, in particular, the time development of compressive strength, flexural strength and elastic modulus was monitored for UHPFRC prepared by varying the water to cement ratio from 0.20 to 0.32. Silica fume, steel fibers and acrylic-based superplasticizer were employed to prepare the UHPFRC mixtures. Optimum workability and mechanical performance were obtained with a water to cement ratio of 0.24. Thermal conductivity was determined for the same UHPFRC, in the presence and in the absence of steel fibers. The scope was to evaluate the effect of steel fibers on the thermal conductivity coefficient, in order to predict the UHPFRC capacity for heat loss. This information as well as its drilling characteristics, in order to test its suitability to be machined, could be essential for possible fields of application such as in mechanical engineering, where UHPFRC materials can be employed as high abrasion-resistant dies in the molding process of metal and polymer products. (C) 2011 Elsevier Ltd. All rights reserved.