Weathering Effects on the Engineering Properties of Sydney (Yellow Block) Sandstone when used as a Building Material

Sydney (Yellow Block) Sandstone is the primary building material used in many nineteenth century buildings in Sydney, Australia. As a natural material, it is subject to deterioration in the salty environment and in extreme cases will need to be removed and replaced. Two cornice pieces have been removed from State Heritage Registered, the Australian Museum due to evidence of visual decay patterns including surface degradation, slight sanding, granular disintegration, contour scaling and flaking, pitting, discoloration, soiling, alga growth and there are missing parts. Stone samples removed from within these building elements were tested for their engineering properties after over 100 years of natural exposure. It was found that the stone has become weaker, softer, less durable, and has an increased capacity to absorb water. The stone was found to be more susceptible to attack from sodium sulfate ingress as opposed to sodium chloride, which would have contributed to the weathering effects noted on the stone. The degree of exposure experienced by each building element was also found to be a factor in the loss of stone quality.     

Effect of the joint type on the bearing capacity of a multi–drum column under static load

The results of an experimental study on the effect of the joints between the blocks on the ultimate bearing capacity of a multi-drum column loaded to centric vertical force and horizontal force in the middle of its height are shown. The column is approximately 2.5 m high, with one hinge at the top and another hinge at the bottom. Four types of joints between the blocks were considered: a dry joint (column C-DJ) and joints with stone powder (column C-SPJ), lead (column C-PBJ), and epoxy (column C-EPJ). The applied vertical and horizontal forces, horizontal displacement, vertical strains, and horizontal circumferential strains in the middle of the column height, as well as shortening of the column, were measured. Under axial compression, ratios between the ultimate load bearing capacities of tested columns were C-EPJ: C-DJ: C-SPJ: C-PBJ = 1: 0.68: 0.59: 0.51. The bearing capacity of the tested columns with regard to the horizontal force depended on the level of the applied centric compression force. Columns with soft joints (C-PBJ, C-SPJ) had the largest shortening and the largest horizontal displacements for the equal forces.