Concrete Masonry Prism and Wall Flexural Bond Strength Using Conventional Masonry Mortars

ASTM C270-86a “Mortar For Unit Masonry” lists different types of mortar (i.e., M, S, N, O) that can be produced from either a proportion or a property specification. This is the first ASTM standard that has allowed the use of masonry cements alone in production of all mortar types via the proportion specification. There has been concern by some members of the building community with regard to masonry assemblage performance of such mortars. The Construction Research Center at the University of Texas at Arlington has conducted an investigation of the flexural bond strength of stack bonded prisms using ASTM C 1072 Bond Wrench Technique and full scale 4' × 8' walls. This paper describes the results of prisms constructed using eight masonry cement mortars and three portland cement lime mortars. Prisms are evaluated at 28 days and six months age. Both laboratory curing and outside curing are examined. The wall tests evaluate two Type S mortars at 28 days.