Foamed concrete incorporating mineral admixtures and pulverized ceramics: Effect of phase change and mineralogy on strength characteristics

Abstract

Different microstructural changes occur in cement based materials as a result of the interaction between the aggregate particles and paste matrix, during mixing, compaction and placement. Such intrinsic modifications, in terms of paste density, interfacial transition zone, permeability and others, tend to improve or lessen the strength properties of concrete. This study evaluates the microstructure, mineralogy, phase change and strength characteristics of foamed concrete containing fly ash and pulverized ceramics. Portion of ceramics, which were generated from floor and wall tile wastes, and finer than 4.75 mm sieve, along with fly ash, were used as a partial replacement of river sand and cement, respectively. The foaming agent used was aluminum powder. However, other constituents were kept constant. Samples of 150 mm concrete cubes and 100 × 100 × 500 mm prisms were prepared, and cured in water for 3, 7, and 28 days, for compressive strength and flexural strength determination at the stipulated days. The microstructure, mineralogy and phase change of selected samples were determined using Scanning electron microscope, X-ray diffraction, and Thermogravimetric Analyzer-Differential Scanning Calorimeter, respectively. The ceramics based foamed concrete exhibited lower slump compared to conventional mixture, mainly due to its aggregate higher water absorption capacity. A 100% ceramics based mix gave strength in somewhat closeness to that of conventional mixture, and it was evidently shown by a lower amount of Portlandite (Ca(OH)2) dehydroxylated between 420 and 550 °C burner temperature for this mixture. The study demonstrates the possibility of incorporating ceramics along with mineral admixtures such as fly ash and aluminum powder for production of foamed concrete.