ALUMINA-SILICA RICH CLAY BRICK WASTE IN
HYDROTHERMALLY TREATED CEMENT-BASED
34th Our World in Concrete and Structures (OWICs) - 2009
A Ray*, CBIR, University of Technology, Sydney, Australia
H Connan, CBIR, University of Technology, Sydney, Australia
B Liu, CBIR, University of Technology, Sydney, Australia
P Thomas, CBIR, University of Technology, Sydney, Australia
(Key words of the Paper)
An urgent need for creative, sustainable approaches, which minimise the
environmental impact of conventional Portland Cement (PC) -based construction materials, is recognised throughout the world. In recent years intensive research has been directed to the use of alumino-silicate materials to produce blended PC. The reduction of CO2 emissions, through the minimisation of PC consumption in the manufacture of PC-based construction products, and utilisation of industrial byproducts, to limit environmental impact, are the principal drivers of this worldwide activity. A number of supplementary cementitious materials (SCMs) containing alumina and silica such as fly ash, granulated blast furnace slag and silica fume are well known additives for the production of blended PCs due to their pozzolanic properties. The potential of other by-products such as those from the construction and demolition industry are less known however, even though they represent an excellent source of reactive alumina and silica-rich material.
This paper deals with fired clay bricks (CB), generated as a waste product from construction and demolition activities, and their value as an additive in the manufacture of PC-based construction products. The research findings reported in this paper are from laboratory scale experiments conducted under hydrothermal conditions in an autoclave where finely ground CB waste was incorporated in the mixes. From a combination of analytical techniques including X-ray Diffraction, Differential Thermal Analysis, Scanning Electron Microscopy and solid-state Nuclear Magnetic Resonance, it was established that the aluminosilicate phase in the fired clay bricks promoted the development of the tobermorite, the principal binder in most calcium silicate products under hydrothermal conditions. The use of CB waste as a cement
replacement for the manufacture of these products was also demonstrated as a viable option.