TOPOGRAPHICAL SURFACE ANALYSIS OF PASTE AND CONCRETE MADE WITH BLENDED COMMERCIAL CEMENT

Abstract

This paper presents the findings of the evaluation of the properties of cementing materials elaborated by mixing commercial Portland cement (CPC), fly ash (FA) and blast furnace slag (GBFS). Initially, a total of 30 different samples of mixes were evaluated in terms of compressive strength in order to determine the optimal proportions of binary and tertiary mixtures of the raw materials. As a result, four representative  blends  of  the  optimal  combinations  were  characterized  during  the  setting  and  hardening  process.  The  compressive strength  development  of  mortar  and  concrete  samples  was  studied.  The  findings  of  this  analysis  show  that  the  commercial  cement blended with fly ash and blast furnace slag presents a decrease in the mechanical strength behaviour regarding to CPC, because of the existing additions incorporated by the manufacturer, which decreased the possibility  of FA and GBF reactions. Finally, concrete and cementing pastes were analysed with a high resolution microscope during different ages. The superficial topographic analyses of the mortar  allow  us  to  relate the  cementitious  capacities  of  the  materials  with the  topographic  details,  highlighting  the  high  topographic intensity and low uniformity in the mortar with the addition of FA and GBFS. The cementing material corresponded to the one used in mortars and concrete which got the lowest strength results in the compression test.