الفهرس 
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Abstract
Environmental conditions influence the performance of cement composites. This work provides in-depth knowledge of Portland cement hydration at different initial temperatures (cold and hot). The word “smart” mentioned in the thesis title doesn’t mean the cement itself is smart, but it refers to the smart technologies used in the study to explore the thermal and mechanical properties of cement composites at an early age. These technologies are acoustic emission (AE) and computational modeling.
To assess different mechanisms of cement composites at an early age under initial cold temperature during placement, evaluation of cement hydration utilizing systems without causing damage is of high significance. A high-sensitive, non-destructive method for continuous monitoring of structural changes during the lifetime of cement-based material composites is confirmed by the acoustic emission (AE) technique. Cement composites (CEM II): cement paste and cement mortar, at different water to cement ratios, and two different initial temperatures 1, and 8 °C were studied during the first 72 h of hydration by AE testing. AE could identify, through the captured signals, various physical changes during hydration. According to cement mortar, the K-means clustering algorithms of detected AE signals were applied using MATLAB to analyze the correlations between these signals and the cement hydration stages. The cement hydration was also detected after 3 days with X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and the microstructure was conducted by Field Emission Scanning Electron Microscopy (FE-SEM). Furthermore, the Virtual Cement and Concrete Testing Laboratory (VCCTL) and ANSYS finite element modeling (FEM) were used to simulate the heat of hydration of cement mortar. The experimental and numerical data were evaluated to check the possibility that computational modeling can replace costly experiments.
Moreover, at an early age, the temperature rise in mass concrete is attributable primarily to the propagation of heat due to an exothermic reaction of cementitious materials and water. The temperature variation in the mass concrete between the core and its surfaces results in the development of thermal stresses. It might occur cracking if these stresses surpass the gained tensile strength of concrete. This work compared experimental and numerical outcomes of heat generation in concrete mould 0.15 m × 0.15 m × 0.15 m in size. Four concrete mixtures with GGBS replacement to cement 0, 10, 30, and 50% were used in the study. VCCTL software was utilized for obtaining the degree of hydration and adiabatic temperature of the four mixtures. Finite element modeling of these mixtures observed good agreement with experimental testing captured by the thermometer. Following that, numerical simulation was employed to study the impact of the block size (cubic models with edge length 0.5 m, 1.0 m, 2.0 m, and 3.0 m) on temperature rise and the associated risk of cracking in mass concrete blocks.