Mechanical and Environmental Proprieties of UHP-FRCC Panels Bonded to Existing Concrete Beams

Tomoya Nishiwaki,Oscar Mancinelli,Yuka Adachi,Alessandro Pasquale Fantilli

doi:10.3390/su13063085

Abstract

Among the techniques used to retrofit existing reinforced concrete structures, methods involving Ultra High Performance Fiber Reinforced Cementitious Composites (UHP-FRCC) are widely regarded. However, current practices make the use of this material for in-situ application expensive and complicated to perform. Accordingly, a new method to strengthen existing concrete beams by applying a precast UHP-FRCC layer on the bottom side are introduced and described herein. Two test campaigns are performed with the aim of defining the best conditions at the interface between the reinforcing layer and the existing beam and to reducing the environmental impact of UHP-FRCC mixtures. As a result, the eco-mechanical analysis reveals that the best performances are attained when the adhesion at interface is enhanced by means of steel nails on the upper surface of the UHP-FRCC layer, in which 20% of the cement is replaced by fly ash.

Highlights

Several studies aim at finding the best way to strengthen concrete columns and beams
UHP-FRCCs have brought the interest of many researchers, who assert that for both new and existing structure a new construction era has started [9]
Cast-in-situ coating layers, made of UHP-FRCC and cured at ambient conditions, are used to enhance the bearing capacity and stiffness of exiting reinforced concrete (RC) beams [10], and to repair those damaged as well [11]. This strengthening procedure requires laborious formworks and long casting procedures compared to the use of Fiber Reinforced Polymer (FRP)

Summary

Introduction

Several studies aim at finding the best way to strengthen concrete columns and beams.Among the possible solutions, reinforced concrete (RC) jackets and steel cages are the most used [1,2]. Cast-in-situ coating layers, made of UHP-FRCC and cured at ambient conditions, are used to enhance the bearing capacity and stiffness of exiting RC beams [10], and to repair those damaged as well [11]. This strengthening procedure requires laborious formworks and long casting procedures compared to the use of FRP. It is not easy to apply cast-in-situ layers on the bottom of beams because of the gravity action For these reasons, some studies have been devoted to the mechanical performance of precast

Methods

Results

Discussion

Conclusion