Thermomechanical Behavior of High-Volume Fly Ash Concretes

In this work, concretes with high levels of fly ash replacing portland cement were elaborated. The concretes 'properties in the fresh state (consistency, workability, and heat of hydration) and in the hardened state (compressive strength, modulus of elasticity, conductivity, void index, water absorption, and density) were measured. Microstructural and thermal characterization were performed. Numerical simulations were performed to analyze the heat exchange during the cement hydration process. Statistical analysis was adequate, and a proposed regression model was validated for the high-volume fly ash concrete, with 60% replacing the portland cement. This concrete presented values of mechanical strength (33.38 [+ or -] 3.99 MPa) and modulus of elasticity (38.58 [+ or -] 0.81 GPa) which confirms its use as structural concrete. This concrete showed low heat of hydration, a reduction of 23% in relation to the reference concrete (without fly ash) during its curing process, and its microstructure presented a lower level of cracking. Keywords: concrete with high levels fly ash; factorial planning; micro-structure; numerical simulation; thermal and mechanical properties.