Flexural performance of pre-cracked UHPC slabs exposed to aggressive environments

The upscaling of innovative materials from laboratory testing to real-scale scenarios is a critical aspect, particularly for the construction sector. To bridge this gap, the present study investigated the experimental flexural response of pre-cracked one- and two-way Ultra-High Performance Concrete (UHPC) slabs. Three different UHPC mixes were adopted, two of them incorporating cellulose nanocrystals and alumina nanofibres, respectively. The experimental results were then compared to a theoretical model, featuring a non-linear analysis coupled with yield line mechanisms defined according to the crack propagation patterns observed experimentally. The theoretical model accurately reproduced the observed experimental response. Therefore, long-term serviceability and ultimate limit state performances of a real-scale unreinforced UHPC structure could be predicted including the evolution of the constitutive behaviour of the material over time. Constitutive models based on the interplay of pre-cracking, self-healing, and aggressive exposure scenarios were implemented to account for the durability performance of the investigated UHPC mixes. The role of UHPC durability in maintaining long-term structural performance in aggressive exposure scenarios was confirmed. The outputs of the study contribute to paving the way for a durability-based design of UHPC structures to predict, through the evolution of the material performance over time, the structural service life and anticipate the to-be-planned maintenance.