Projecting the resiliency of nano-modified cementitious composites with hybrid BFP/PVA fibers in shear key joints

Abstract

Effective bond strength at the interface between conventional concrete (CC) and high-performance fiber-reinforced cementitious composites (HPFRCC) is vital for applications like shear key for bridge joints. This study investigated the suitability of HPFRCC incorporating various constituents (cement, slag, as well as nano-silica), with only basalt fiber pellets (macro-BFP) or hybrid fiber systems including macro-BFP and micro-polyvinyl alcohol (PVA) fibers. BFP is a new emerging class of basalt fiber strands protected by a polymer coat. Experimental results (slant shear, pure shear, rebar pull-out, etc.) were used to develop modeling [homogenization/finite element modeling (FEM)] components to evaluate the effect of HPFRCC mixture design parameters on the mode of failure and bonding capacity with CC and steel rebar. After verification, these model components were integrated in a full-scale shear key joint model to project the field performance of the developed HPFRCC. The results revealed that nano-silica had a significant effect at improving the HPFRCC bonding strength capacity with CC and steel reinforcement. Whilst increasing BFP dosage (4.5%) in the nano-modified composites resulted in reduction of the interfacial bonding with CC, it significantly improved the rebar interfacial bonding and ultimate shear key capacity of the joint. Comparatively, the inclusion of 1% micro-PVA fibers in the nano-modified composites comprising macro-BFP resulted in the highest increase in shear resistance force, interfacial bonding with precast CC and shear reinforcement dowels, and ductility which suggests their promising potential to be employed in shear key jointing applications.