Özet:

Reactive Powder Concrete (RPC) is composed of very fine powders (cement, sand, and pozzolanic materials), and superplasticizers. A very dense matrix is found, and this tightness provides RPC with ultra-high strength and durability. Recently, using supplementary cementing materials associates greatly with ultra-high strength and the mix design of ultra-high performance concrete (UHPC). These materials could be natural, by-products or industrial wastes. They could be also less energy consuming and little time produced materials. Silica fume (SF), rice husk ash (RHA) and granulated blast furnace slag (GBFS) etc. are among the major supplementary cementing materials utilized. The detailed experimental investigation done to study the impact of partial alteration of cement with SF, RHA, and GBFS on concrete properties. This study aims to a minor replacement of Portland cement by SF, RHA and GBFS to reach UHPC. Twenty-five different concrete mixes (fc =150.1 to 188.2 MPa) with and without SF, RHA and GBFS were prepared with local materials in Egypt. Concrete mixes were cast with 0, 10, 15, 20, and 25% cement replaced by either SF or RHA, and another proportions taken combination between SF and RHA or SF and GBFS or RHA and GBFS about percentages from 10 to 15%. The mixes were tested for slump flow, air content, mechanical properties and water permeability. The findings of hardened properties indicate that optimum level for partial changing of cement by SF and RHA was 20% and it is observed that though the strengths of SF or RHA concrete goes on decreasing after the 20% addition of SF or RHA. Test results have indicated that RHA exhibits lower pozzolanic activity than SF.

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