Geopolymer composites using natural pozzolan and oil-shale ash base materials: A parametric study

Abstract

The mechanical properties, capillary porosity and microstructure of Geopolymer (GP) composites made using different natural Jordanian base materials were investigated. GP mortar mixtures were prepared using oil shale ash, Jordanian natural Pozzolan and a blend of both considering different salient parameters related to the composition of alkaline activator and GP binder content. GP mortar specimens (40 × 40 × 160 mm3) cast from 36 different mixtures were left to rest in molds for 24 h before unmolded then exposed to 60 °C temperature to cure for 24 h and finally moved to laboratory shelves to cure for the remainder of the curing periods of 7 and 28 days. Compressive and flexural tensile strengths, capillary porosity, and Scanning Electron Microscopy (SEM) pictures of the hardened GP composite were obtained, analyzed, and compared to study the significance of the study parameters. The results indicate a good potential of producing GP composites using Jordanian natural Pozzolan alone or with oil shale ash for masonry and structural applications with strength grades of up to 24 MPa. A very good statistical correlation was established between the compressive strength and capillary porosity for present GP composites. SEM pictures for GP composites confirm the experimentally-measured mechanical and durability properties.