In-Plane Strengthening of Unreinforced Concrete Masonry Wallettes Using ECC Shotcrete

An experimental program was conducted to investigate the viability of using engineered cementitious composite (ECC) shotcrete as in-plane shear reinforcement for concrete masonry wallettes. Twenty-six mortared or dry-stacked ungrouted and unreinforced concrete masonry wallettes were strengthened through the application of an ECC shotcrete mix, applied either by spraying with a shotcrete machine or by hand trowelling. To determine the effect of applicator experience, ECC was applied by both a professional plasterer and amateur plasterers, with and without supervision. The in-plane shear strength of the strengthened wallettes increased between 340 and 3,471%, depending on the ECC application method. The variability of the strength increase was smaller for wallettes that had mortared joints and an ECC overlay trowelled by a professional plasterer. A set of design equations was also developed to determine the shear strength of a strengthened wallette. The design displacement ductility can be conservatively set equal to 1.9 because of the high variability in the experimentally obtained ductility values. (C) 2014 American Society of Civil Engineers.