Performance assessment of Ultra High Performance Fiber Reinforced Cementitious Composites in view of sustainability

Abstract

This paper presents a sustainability assessment for an Ultra High Performance Fiber Reinforced Cement Composite (UHPFRCC). The concrete composite was designed at Universidade Federal do Rio de Janeiro (UFRJ) and was produced from a Blast furnace slag cement, silica fume, silica flour, wollastonite, steel fibers and superplasticizer and showed superb performances in the field of rheology, material properties and durability, in comparison with regular concretes in general and other ultra high performance concretes in particular. The design of the UHPFRCC is based on the aim to achieve an ultra-compacted cementitious matrix with a skeleton of aggregates ranging from 150 to 600μm and with the packing of the granular skeleton based on the compressive packing model (CPM). The water/binder ratio of the mixture was 0.17 leading to outstanding performances of the cementitious composite. At 28days, the UHPFRCC showed a compressive strength of 162MPa, an elastic modulus of 48GPa, a tensile strength of 10MPa and an equivalent elastic post-cracking bending strength of 35MPa. The material properties´ stress–strain behaviour under compression, tension and bending were measured even as the durability related properties such as capillary water absorption, gas permeability and diffusion coefficient. In order to evaluate the material in view of its sustainability performance, a probabilistic analysis has been employed where UHPFRCC is compared with a regular Grade 40 concrete and with a low environmental impact sewage sludge concrete. From this evaluation a sustainability assessment has been employed in terms of mechanical performance, durability performance and natural materials usage. The results show that within its designated field of application the sustainability profile of UHPFRCC balances with ordinary Portland cement based concretes.