Investigating mechanical properties of ordinary portland cement. Investigating improvements to the mechanical properties of Ordinary Portland Cement (OPC) bodies by utilizing the phase transformation properties of a ceramic (Zirconia).

摘要

The effects of metastable tetragonal zirconia on the properties of Ordinary PortlandudCement were observed during which the effect of crystallite size pH on the preparationudsolution, precursor salt, and the presence of co-precipitates, Fe(OH)3, SnO2 and SiO2 onudthe crystallization temperature, enthalpy and crystal structure, immediately following theudcrystallization exothermic burst phenomenon in ZrO2 were measured. Thermal analysisudand x-ray methods were used to determine crystallite sizes and structures immediatelyudfollowing the exothermic burst. Comparisons were made for zirconias prepared fromudoxychloride, chloride and nitrate solutions. The existence of tetrameric hydroxidecontainingudions in oxychloride precursor is used to rationalise low values ofudcrystallization enthalpy.udThe position of the crystallization temperature, Tmax was not dependent on crystallite sizeudalone but also on the pH at which the gel was made, the surface pH after washing, and theudpresence of diluent oxides. Enthalpy v r1/2 and Tmax v (diluent vol)1/3 relationshipsudindicate that surface coverage effects dominate a surface nucleated phenomenon. Theuddata established for ZrO2 systems was used to develop tetragonal-ZrO2-SnO2 powdersudcapable of improving the mechanical properties of Ordinary Portland Cement discs.udThe ZrO2-OPC discs were prepared by powder mixing, water hydration and uniaxialudpressing. Vicat needle tests showed that tetragonal-ZrO2 increases the initial setting rate.udMicroscopy indicated that porosity distribution changes near to ZrO2 particles. Zirconiaudhas also been introduced into OPC discs by vacuum infiltration methods developed forudsolutions and colloidal suspensions. Comparisons between OPC discs and the OPCtetragonaludZrO2 composites have been made on the basis of diametral compression strength, Young’s modulus, hardness and toughness (K1c), as estimated by the crackedudindentation method. Bell-shaped curves are found for the way the mechanical propertiesudare changed as a function of Zirconia content.