Effect of different supplementary cementitious materials and superplasticizers on rheological behavior of eco-friendly mortars

The drive towards using eco-friendly binders with increasing proportion of supplementary cementitious materials (SCMs) will lead to the development of more complex mixtures. However, the availability of fly ash (FA) would not cover future needs due to restrictions on the combustion of coal in power plants. Accordingly, the addition of limestone filler (LF) has an inherent advantage throughout the world of its availability in large deposits. The first main aim of this study was to determine the effect of high-volume LF used as Portland cement replacement with up to 60% on the rheological properties of cement mortar compared to the FA and the slag (BFS). Unlike FA and BFS, an increase in LF replacement reduced the rheological properties of the mortar. The relationship obtained between relative solid concentration and rheological properties of mortar with different SCMs was reasonable. The second aim of this study was to determine the rheological behavior of the mortar with different superplasticizer (SP) admixtures. Three SP types were utilized, ether-polycarboxylic modified (SP1), phosphonate modified (SP2) and new generation of polycarboxylate (SP3), with various dosages. The results show that, SP2 reduced the rheological properties better than SP1 and SP3 with dosages of less than 1%.