الفهرس | Only 14 pages are availabe for public view |
Abstract The environmental impact associated with the production processes of Portland cements (OPC), the main hydraulic binder since the 19th century, includes: greenhouse gases emissions, high energy consumption and natural resource exploitation. Also, the recognition of durability problems in older structures based in OPC has acted as an impetus to transfer the microstructural and hydration chemistry studies of these conventional binders to develop a novel generation of cements with durability and environmental sustainability. The partial replacement of OPC by active nano-powders or supplementary cementing materials, such as ground granulated blast furnace slag (GGBFS), silica fume (SF), rice husk ash (RHA), metakaolin (MK) or fly ash (FA), are examples of those new binders and constitute a significant contribution to the eco-efficiency of the global economy. This study investigates the reinforcing of raw materials rich in silica and alumina such as slag, flyash and silica fume with various fiber types (steel, carbon, polypropylene and glass) added by specific ratios by weight activated by an alkaline activator sodium hydroxide in order to produce reinforced geopolymer composites. Mechanical properties, water/binder ratio, and compressive strength are discussed. Laboratory techniques of Fourier Transform Infrared Spectroscopy (FTIR), X-ray Fluorescence (XRF), and X-Ray Diffraction (XRD) were utilized to identify geopolymer phases and structures. The results proved that adding different fiber types with specific ratio produced geopolymer composites possessing good mechanical resistance in addition to better physical characteristics like drying shrinkage, water absorption, crack propagation, and post-cracking besides microstructural investigation by Scanning Electron Microscope inferred that the yielded composites have almost compact homogenous structure free of pores. |