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Computer Modeling of the Replacement of "Coarse" Cement Particles by Inert Fillers in Low W/C Ratio Concretes: Hydration and Strength.


pdf icon Computer Modeling of the Replacement of "Coarse" Cement Particles by Inert Fillers in Low W/C Ratio Concretes: Hydration and Strength. (290 K)
Bentz, D. P.; Conway, J. T.

Cement and Concrete Research, Vol. 31, No. 3, 503-506, 2001.

Keywords:

cements; computer models; concretes; blended cements; compressive strength; hydration; particle size distribution

Abstract:

In concretes with water-to-cement (w/c) ratios below about 0.38, a portion of the cement particles will always remain unhydrated due to space limitations within the material. Thus, in many of the high-performance concretes currently being produced, cement clinker is in effect being wasted. This communication examines the possibility of replacing the coarser fraction of a cement powder by an inert filler, to conserve cement without sacrificing material performance. Using the NIST CEMHYD3D cement hydration model, it is demonstrated that for "initial" w/c ratios of 0.25 and 0.30, a portion of the coarser cement particles can be replaced by inert fillers with little projected loss in compressive strength development. Of course, the optimal replacement fraction depends on the initial w/c ratio, suggesting that blended cements need to be produced with the end concrete mixture proportions in mind. This further implies that a cement/inert mixture of specific proportions will only perform optimally in a limited range of concrete mixture proportions.