Influence of sugar-cane bagasse ash and fly ash on the rheological behavior of cement pastes and mortars

In the present study, the effects of a sieved sugar cane bagasse ash (SCBA) and fly ash (FA) on the rheological properties of pastes and mortars were investigated. Cement pastes and mortar mixtures were designed as single ingredient, binary and ternary systems. For the single ingredient system only cement was used. For the binary system, SCBA or FA was used to replace some of the cement. For the ternary systems, combinations of cement, SCBA and FA were used. The rheological tests were carried out with a stress controlled rheometer equipped with a ball measuring system. In addition, mini-slump cone and the flow/spread table tests were carried out to determine the feasibility of evaluating the rheological properties of pastes and mortars from empirical tests. The results indicate that for the binary pastes and mortars, there is an inverse relationship between the yield stress and FA concentration. On the other hand, the shape and size of the particles of the used SCBA produced more viscous and plastic binary pastes and mortars than mixes without the SCBA. When the SCBA concentration was increased, the yield stress linearly increased as well. In the ternary systems, the use of 20% of FA combined with 10% and 20% of SCBA was beneficial producing lower yield stresses than those presented in the binary system. The results obtained with the mini-slump cone and the flow/spread table tests showed a certain relationship with the rheological measurements, but this could not be completely identified.