Ultra-High Strength Concrete (UHSC) is a new generation of cementitious material that can undergo a very high compressive strength, whereas being ductile and durable. The increasing demand on UHSC due to the construction of high-rise buildings and mega projects around the world increased the desire of the designers to improve the durability and mechanical properties of the concrete elements. This study aims to present the development of UHSC by using two types of new generation hyper-plasticizers and microsilica at various contents to improve the resulting performance of UHSCs. Comparative experimental study for various UHSC mixes was conducted in order to achieve a high level of compressive strength (above 100Mpa) at relatively early stages (up to 28 days) without reinforcement at very low w/c without effecting the workability of the concrete mix. The effect of various mix proportions on the homogeneity, workability and the compressive strength of the concretes at various water to cement (w/c) ratios were evaluated. Therefore, main aim of this study is to conduct comparative analysis on the effect of superplasticizer and Microsilica content on water demand, compressive strength and durability of UHSCs.As a research method, Part of the specimens’ w/c ratio maintained constant while other parts had the minimum w/c ratio possible to study the impacts on the compression strength and reach its highest value by taking into the account not losing or sometimes improving the workability of the concrete mixture. Compression test is applied on 100mm dimension cube specimens using the compression test machine with a maximum compression capacity of 200MPa on the 2nd, 7th and 28th days. Mini-slump test was done on the specimens which showed medium to high workability. Mass of the specimens was checked during the mixing process. Images were taken and videos recorded continuously during the entire process in order to analyze the resultant behaviors.
Keywords: Ultra High-Strength Concrete (UHSC), Super-Plasticizer, Microsilica, Compressive Strength.
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