Concretes made of efficient multi-composite cements with slag and limestone

The present paper deals with the performance of concretes made of multi-composite cements with granulated blast furnace slag (GBFS) and limestone (LL) contents beyond the limits of current EN 197-1. The combined application of ground limestone (up to 50%) and GBFS in multi-composite cements can enable a significant reduction in the Portland cement clinker content of cements for the same concrete strength and durability. The lower the wic-ratio the higher is the potential for the efficient use of Portland cement clinker together with limestone and slag. A comprehensive experimental study was conducted to analyze the mechanical properties and durability of concrete made of multi-composite cements at both laboratory and plant scale. The efficient use of Portland cement clinker together with GBFS and limestone is analyzed for different cement compositions and %tic-ratios. An approach for the optimization of the slag efficiency is proposed. It was concluded that the efficiency of GBFS increases significantly with decreasing wic-ratio and slag content. Due to the limited availability of slag, the slag content was limited to 30 wt.-% for multi-composite plant cements. The performance of concretes made of such cements containing 50%, 35% and 20% clinker and 20%, 35% and 50% limestone respectively were experimentally analyzed. The results revealed that concrete made of cement with 50 wt.-% clinker, 30 wt.-% GGBFS and 20 wt.-% limestone and a w/cratio of 0.50 could exhibit comparable hardened properties compared to reference concrete made of slag cement CEM 111/A 42.5 N (with 50 wt.-% slag) with the same %tic-ratio. Concrete made of cements with clinker content of 35 wt.-% and a reduced wic-ratio of 0.40 could result in a performance similar to the reference concrete made of CEM III/A 42.5 N. Further reduction of clinker content to 20 wt.-% was possible only at a low %tic-ratio of 0.35. Life cycle assessment (LCA) analysis revealed that the application of such multi-composite cements can lead to a concrete with a remarkable lower global warming potential up to about 35% compared to the concrete made of German average cement with a similar performance. (C) 2018 Elsevier Ltd. All rights reserved.