Enhancing Concrete Properties by Using Silica Fume as Reactive Powder and Portland Cement-Clinker as Reactive Aggregate

摘要

In this research, techniques of cement paste strengthening and interfacial transition zone (ITZ) microstructure modification were simultaneously used to enhance the concrete engineering properties and a new concrete, named reactive-powder and reactive-aggregate concrete (RPRAC), was introduced. For this purpose, 18 wt.% of cement in concrete mix design was replaced with silica fume to strengthen the cement paste according to reactive powder concrete (RPC) technology and an optimal part of the sand in the concrete mix design was replaced with portland cement (PC) clinker as a reactive synthetic aggregate. RPRAC was then compared with RPC and normal concrete (NC) as controls in terms of workability, setting time, different-age compressive and flexural strengths, chloride penetration depth, open-pore volume, and water absorption. Simultaneous pozzolanic reactions of silica fume and surface hydration reactions of PC-clinker resulted in effective microstructural refinements both in hardened cement paste and ITZ. The achieved results showed that compressive strength of RPRAC was increased by 121% and 170% at 28 days compared to RPC and NC, respectively. The chloride penetration depth in RPRAC decreased by about 71% and 87% after 28 days of immersion in a NaCl solution compared to RPC and NC, respectively.