Preparation of glass-ceramic materials from basaltic rocks and by-pass cement dust

Glass-ceramic is a generic name given to materials, which first melted, formed into glass and then crystallised in controlled manner to yield nonporous polycrystalline products of unexpected properties. Controlled crystallisation usually involves two stages, a nucleation stage and a crystallisation stage,(1–3) that aim to produce fine grained uniform textures consisting of small randomly oriented crystals bonded by some residual interstitial glass without voids, micro-cracks or porosity.(4,5) Glass-ceramics can have significant advantages over conventional glass or ceramic materials by combining the flexibility of formation and inspection of glass with good mechanical properties. Glassceramics are fine grained polycrystalline materials formed when glasses of suitable composition are heat treated and thus undergo controlled crystallisation,(6) and they are characterised by physical and mechanical properties such as high bending strength and hardness, good corrosion resistance and abrasion resistance. The raw materials used for the present investigations include basaltic rocks from Sinai and by-pass cement dust. Basalts are the main raw materials for iron-rich glass and glass-ceramic materials. They are composed of silica, alumina, iron oxide, calcia, magnesia as major oxides and, of lesser importance, soda, potassia, titania and manganese and phosphorus oxide as well as trace amounts of other species.(7) They are characterised by low viscosity, which enables production of polycrystalline materials by applying short production cycles at low temperatures, which is why, many researchers are keen on studying the melting and crystallisation behaviour of different igneous rocks and characterising the materials obtained.(8) The high chemical durability of natural basalts mean basalt as well as basaltic glass-ceramic materials have been developed for nuclear waste disposal.(9) For vitrification of various hazardous industrial wastes basaltic materials have many important properties and useful applications as they can increase the bending strength of tiles while preserving the physical-chemical properties required and improving sintering quality. Considering the main component of the raw materials compositions for making glass ceramic materials they can be used as heat and fire resistant materials because of their low thermal conductivities, high oxidation resistance, and high softening and melting temperatures.(10) In addition, basalt fibre has good tensile strength properties compared to other glass fibres. However basaltic fibre composites have a lower tensile fire resistance than an equivalent glass fibre laminates when exposed to the same heat flux.(11) Not only is basalt is used in road paving works and as a construction material for building blocks, but also it can be contributed in cement manufacturing where it results in a higher compressive resistance without the addition of aggregates.(12) The cement manufacturing industry is one of the Preparation of glass-ceramic materials from basaltic rocks and by-pass cement dust