Results of a test program to determine flexural bond strengths associated with Type M, S, and N portland cement/lime mortars under controlled test conditions were reported in the February 1991 issue of The Masonry Society Journal. Subsequent to that investigation on portland cement/lime mortars, similar tests were performed using masonry cement mortars. In these tests,flexural bond strengths were determined for Type S and Type N masonry cement mortars, using special standard concrete brick. The laboratory tests were designed to control materials, prism fabrication, curing, and testing. The mortar materials included Type S and Type N single-bag masonry cements and standard Ottawa sand. Results of tests conducted at Construction Technology Laboratories, Inc. (CTL), at the research laboratory of the National Concrete Masonry Association (NCMA), and at the University of Texas at Austin (UTA) are summarized and discussed in this paper.
For each of the mortar mixes, the initial flow, water retention, air content, and cube compressive strengths at 7 and 28 days were determined. Six prisms,each consisting of six standard concrete brick and five mortar joints, were fabricated and tested for flexural bond strength at 28 days according to ASTM C 1072-86, Method for Measurement of Masonry Flexural Bond Strength. Tests of some mortars were duplicated in different laboratories. The mean, standard deviation, and coefficient of variation were calculated for the 30 joints tested in each test series. Results provide a general indication of the flexural bond strength of masonry cement mortars under the test conditions of the program.