Influence on rheological behavior of montar with addition of fly ash from bayer process fluidized bed boilers and construction

Abstract

Fly ash obtained from coal combustion in fluidized bed boilers has been used in civil construction to partially replace Portland cement, due to its pozzolanic activities, and thus minimizing the accumulation of industrial waste. The rheological characteristics of six composition of mortars were studied on six differents proportions of cement, construction waste generation (CWG) and fly ash (FA). For the rheological tests, a coaxial cylinder viscometer was used, varying the shear rate from 0 to 600 s-1 at 28 ºC, [1] in the interval time of 120s (in 120s time interval). Granulometric analysis, X-ray diffraction (XRD), X-ray fluorescence (XRF) and scanning electron microscope (SEM) tests were performed. The results showed that fly ash incorporation is the main factor for changing behavior from rheopecthic to thixotropic, in the avaluated traces. The experimental data was well fitted in Herschel-Bulkley rheological model.