| dc.description.abstract | The modern construction industry has been long waiting for a material that can fulfill the requirements of very high compressive and flexural strengths in addition to durability. The Ultra-High-Performance concrete finally seems to be the solution to these high requirements set by the latest engineering problems. Where UHPC performs extremely well in terms of strength and durability, there the production of UHPC also causes high damage to the environment in terms of CO2 emissions in the production and high cost. Since the UHPC is known to have an extremely high content of Clinker which gives the concrete its high strength but also causes high energy consumption during production. This study focuses on finding the solution to these issues by developing a UHPC with environmentally friendly constituents producing extremely low CO2 emissions. The Low-Heat Slag Cement with Blast furnace slag content of up to 70% and only 30% clinker has been used as a primary binder in this study, in addition to Fly Ash, GGBFS, and Micro-Silica as residual green secondary binders.
The usage of Low-Heat Slag Cement and secondary binders were studied in terms of their effects on the workability of fresh UHPC as well as Hardened mechanical properties. Under two different curing Regimes of normal water bath (Curing-A) and Air Tempering at 90oC (Curing-B), it was observed that the curing method-B provides an early-age very high 7-Days compressive strength up to 200 MPa. While curing method-A providing 28-Day strengths up to 150 MPa. The Observations in the study show that the higher slag content in the UHPC provides good Flexural and Tensile strengths up to 25 MPa and 12 MPa, respectively, in combination with Micro-steel fiber volume of 1.5% to 3% but show less compressive strengths. Moreover, it was also observed that mixes with FlyAsh show better workability over time as compared to mixes with higher slag content. Furthermore, The environmental impact of the mixes was studied and it was concluded that it is possible to attain 28-Days normal curing Compressive strengths up to 120 MPa with very low clinker contents of only 10% reducing the overall damage to the environment up to 90%. | |