R. PAVE (1) and H.C. UZOEGBO FIMS (2)

(1) Postgraduate Research Student

(2) Associate Professor of Structural Engineering, University of the Witwatersrand, Johannesburg, South Africa


The compression strength testing procedure for masonry units with unsupported projections is not well documented and can be quite complex. Most laboratories use cores taken from the samples for compression testing. This paper is based on the development of alternative testing methods for dry-stack (mortarless) interlocking masonry units and walling systems. The blocks rely mainly on the interlocking keys for stability and were made of compressed soil-cement extruded under a pressure of about 10N/mm2. The blocks are developed, marketed and certified for use in construction in South Africa by AGREMENT SA [1]. The product has achieved reasonable commercial success in parts of Africa, Asia and South America mainly due to its simplicity, savings in mortar and speed of construction compared to conventional masonry. In order to establish suitable test methods, axial compression tests were conducted on full scale block units using platens that match the complex surface configuration of the units and in-service load paths. Cubes were also cored from the masonry units and tested as control samples. The results show that the method of testing and the moisture content are important factors in the strength of the masonry units. Provisions on conventional masonry walling are used for comparison. The test results were used to develop an empirical model for the prediction of the load capacity of the dry-stack interlocking block units.

Key words

dry-stack masonry, compressive strength, interlocking blocks, wall panels