Improvement of the reactive powder concrete properties by incorporation of the mineral additives

Ultra high performance concrete, which has a compressive strength value in the range of 200- 800 MPa, is called Reactive Powder Concrete (RPC). RPC is generally produced by lowering the CaO/SiO2 ratio with the incorporation of silica components, by reducing the maximum size of aggregates, improving the compacted density by optimization of the granular skeleton of mixture and using superplasticizer to minimize the water / cement ratio. Application of pressure before and during setting and high pressure steam curing (autoclave curing) are additional methods to increase the strength level. Furthermore, to improve the ductility, generally short steel fibers are introduced into the RPC mixtures. In this study, initaly aggregate types and grading, silica fume content and heat treatment conditions optimized to obtain superior compressive strength. In the second stage The main bindery ingredients were pulverized fly ash (PFA), pulverized granulated blast furnace slag (PS), binary and ternary combinations were replaced with Portland cement (PC) at specified ratios. PFA and PS were alternatives reactive silica sources and determined optimum CaO/SiO2 ratio which give max compressive strength in autoclaved curing. So some of silica fume can be taken out to the mixtures. And than Class C fly ash and granulated blast furnace slag can also supplied silica to the system. And than created new mineral additives mixes which have less SF but same compressive strength value in autoclaved curing. In the thirth stage, three different curing methods (standard, autoclave curing and steam curing) were applied to the new mineral additives mixes and conrol mix. Mineral additives test results were presented comparatively with the control mix which has only cement and SF as a binder. In the last stage, application of pressure before and during setting with high pressure steam curing is additional methods to increase the strength level. These results indicate that the reactive powder concrete can also be produced with the incorparation of PFA and PS besides combinations of powerful binders SF and PC.