Effect of burning conditions on properties of artificial hydraulic lime mortar obtained from limestone and siliceous waste materials

The present study was carried out to produce an artificial hydraulic lime for repair and conservation of historic masonry. Lime mortar is preferred to cement based mortar for conservation work because it is more compatible with stone and ancient brickwork, as well as being a more sustainable material. The study focused on the effect of burning conditions on the properties of an artificial hydraulic lime mortar obtained by burning limestone and siliceous waste materials. The raw meals were prepared from five types of siliceous materials obtained as byproducts from industrial processes (pulverised fuel ash, glass cullet, silica sand, crushed rock and spent oil shale) with the amount of silica between 3 and 16%. The raw meal was burned in an electric furnace at 975°C for 3 h. The mortar was prepared by mixing hot slaked lime putty (water/lime ratio ~1.6) and 'Gowrie' sand at a lime/sand ratio of 1: 3 by weight. The limes and lime mortar were prepared and tested according to BS EN 459-2:2001. The investigations carried out on the products included free lime analysis, strength test and microstructural examination. The results show that the glass cullet lime is the most hydraulic product and can be classified as feebly hydraulic. It suggests that this hydraulic lime could be produced using a traditional kiln at a low cost. © 2006 Institute of Materials, Minerals and Mining.