Influence of geometry on creep and moisture movement of clay, calcium silicate and concrete masonry
This investigation involved creep and moisture movement measurements for about six months on 13-course clay (Engineering class B) and calcium silicate brickwork, and 5-course concrete blockwork, consecutively. Four different geometries of masonry were built, namely: single-leaf wall, cavity wall, hollow pier and solid pier, respectively having volume/surface area (V/S) ratios of 44,51,78 and 112 mm. Deformations were also measured on one-brick wide 5 or 6-stack high model brickwalls which were partly sealed to simulate the V/S ratios of the corresponding 13-course brickwork. At the same time, deformations were also measured on individual mortar prisms and brick or block units in order to verify composite model expressions for predicting masonry movements. Simulation of moisture diffusion of the corresponding mortarjoints and embedded bricks or block were made in terms of V/S ratio by partial sealing of the individual mortar prisms and brick or block units. The tests reveal that the modulus of elasticity to be independent of masonry geometry. However, there is a clear influence of geometry on the vertical ultimate creep and moisture movement of all the masonry types i,.e. creep and shrinkage increase with a decrease of V/S ratio. A similar trend occurs for horizontal shrinkage except for the clay brickwork which undergoes moisture expansion. Deformations of the model walls show reasonable agreement with the 13-course brickwork. When results of individual mortar and brick/block specimens are inserted in composite models,the predicted strains show good agreement with the measured strains, particularly in the vertical direction. There is no consistent pattern in the distribution of load and moisture strains for the different masonry geometries, and the measurements reveal that actual strains can be up to 100% higher than the average strains.