"Betão" de ultraelevado desempenho reforçado com fibras metálicas

Abstract

In the scope of the PhD research of the first author, a greener UHPFRC was developed, using raw materials available in Portugal for rehabilitation/reinforcement applications. The new UHPFRC, besides incorporating lower quantities of cement and silica fume, included a national subproduct material from the oil industry. Several properties were evaluated: autogenous shrinkage, compressive strength, uniaxial tensile strength, water absorption by capillarity, carbonation, chloride ion penetration, and susceptibility to expansive reaction (alkalis and external sulfates). The new UHPFRC achieved a compressive strength of 147 and 156 MPa after 28 and 90 days of water curing, respectively; a peak tensile strength of 11 to 15 MPa and peak strain between and 0.27-0.47%. The durability indicators of the new UHPC (without fibres) demonstrated excellent behaviour against various aggressive agents and a very low porosity with the absence of capillary pores. These results, combined with its self-compacting and low autogenous shrinkage, confirm the importance of this new generation of "concretes" for high-tech construction.