Tensile Characterization of an “Eco-Friendly” UHPFRC with Waste Glass Powder and Glass Sand

A new type of ecofriendly ultra-high-performance glass concrete (UHPGC) was developed at the Université de Sherbrooke using waste glass with varying particle-size distributions (PSD). The compressive strength was higher than 150 MPa and mini-slump spread diameter higher than 250 mm. Two UHPGC with different compositions were investigated: one mixture containing glass powder as a cement replacement material and the other mixture containing glass powder and glass sand as a replacement of both binder and fine aggregates. Both mixtures contain 2% by volume of micro steel fibers with aspect ratio (length/diameter) equal to 65. Two curing regime were used (hot curing and normal curing) and the effect of this different curing regime on the tensile behavior has been also investigated. A total of six sets of specimens were tested at different ages, equal to 28 and 91 days respectively, including, as a further experimental variable, the flow-induced alignment of the fibers. A novel experimental technique, called Double Edge Wedge Splitting Test (DEWS), recently developed at Politecnico di Milano, was employed to characterize the material tensile response. This is an indirect tensile test technique, in which a compressive load applied to the specimen is able to result into a tensile stress state over a critical ligament section suitably highlighted thanks to specimen geometry and loading set-up. The DEWS test is able, as demonstrated, to provide straightforwardly the tensile stress vs. crack opening response of the cementitious composite with no need for back analysis. The results highlight the possibility of obtaining a strain-hardening composite, also exploiting the favorable alignment of the fibers, and hence to produce an ultra-high performance fiber reinforced cementitious composite (UHPFRCC) with significant sustainable signature, employing considerable amounts of waste material as cement and natural aggregate replacement.