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Influence of Cement Behavior with and without Polymer Nano Composites
Published in Didier Rouxel, Sabu Thomas, Nandakumar Kalarikkal, Sajith T. Abdulrahman, Advanced Polymeric Materials, 2022
Mainak Ghosal, Arun Kumar Chakraborty
Very limited research has been done on the use of nanomaterials in cement concrete involving a polymer which causes the cement matrix to densify by complex process. The term-strength of a cement-based materials is based on the hydration of its clinker components and we know that these clinker consists of various calcium silicates including Alite (tricalcium silicate, Ca3SiO5, sometimes formulated as 3CaO SiO2; C3S in cement chemist notation) and Belite(dicalcium silicate, Ca2SiO4, sometimes formulated as 20CaO SiO2; C2S in cement chemist notation). The final long-term strengths of cement-based materials are dependent on the amount of these cement hydrates, as well as on their crystal shapes, which may be platy, elongated, and rod-shaped. The C–S–H gel so formed along with interlocked hydration crystals forms the dense, impenetrable cement matrix.
An Investigation of the Application and Material Characteristics of Early 20th-Century Portland Cement-Based Structures from the Historical Campus of the Budapest University of Technology and Economics
Published in International Journal of Architectural Heritage, 2020
István Vidovszky, Farkas Pintér
Samples were embedded in epoxy resin dyed with a yellow fluorescein and large format (4x4 cm) thin sections of standard 25 μm thickness as well as polished sections were prepared. Thin sections were analyzed in the optical microscope (Zeiss AXIOScope A1) using transmitted plain (PPL) and cross-polarized (XPL) as well as UV light (UVM) to investigate the mineral composition as well as highlight the porosity and crack pattern in the binders. The binder-to-aggregate ratios (b/a) and the amount of air voids were determined by point counting (JMicroVision) using at least 500 points per measurement (Poole and Sims 2015). The accuracy of the measurements was controlled by using an evolution plot integrated into the software. The maximum grain size of the aggregates was measured in the thin sections, except for the concrete samples PC-1 and 2, where observations during sampling were also taken into account. The polished sections were etched with Nital (1.5 mL of HNO3 in 100 mL of isopropyl alcohol for 6 to 8 seconds, and the residue of the etchant was removed by ethanol (Campbell 1999)) in order to highlight unhydrated cement grains and their microstructure by reflected light (RL) in the optical microscope. The etched surface was then re-polished and coated with carbon to be analyzed by scanning electron microscope (Zeiss EVO15, acceleration voltage 15 kV, probe current 500 pA) coupled with an energy dispersive X-ray spectrometer (Oxford DryCool, EDX spectra collection time 60s). A large number of analysis points and atomic ratio plots were used to characterize unhydrated residual cement grains and hydration products. The internal standards of the Oxford INCA software were used to automatically standardize the measurements. Cement chemists’ notation is used throughout this document with the following abbreviations: A = Al2O3, C = CaO, F = Fe2O3, H = H2O, and S = SiO2. The mineralogical-morphological characterization of cement minerals was based on the assessment of approx. 30 unhydated cement grains in each sample .