RHEOLOGY AS A TOOL FOR TECHNOLOGICAL ADVANCEMENTS IN SELF-COMPACTING LIGHTWEIGHT CONCRETE MIXES

Abstract

This paper outlines a methodology aimed at enhancing the technological performance of self-compacting concrete using lightweight expanded clay aggregate. One of the primary challenges encountered when employing concrete with lightweight aggregate involves displacing expanded clay grains within the solution's liquid phase to ensure necessary fluidity (workability) while upholding high stability (structural viscosity and segregation resistance). To achieve this objective, the rheological parameters of the self-compacting cement matrix have been regulated by deliberately adjusting the functional groups of additives and the microfine mineral filler, employing analytical methods from computer materials science. Through the analysis of rheometric results obtained from investigating various solution mixtures, the most suitable model that describes their rheological behaviour has been identified. The impact of finely dispersed fly ash excipient, a carboxylate superplasticiser, and a stabiliser additive on the rheological parameters of self-compacting lightweight concrete mixes has been established. The inclusion of these complex additives in the composition has enabled substantial alterations in the flow index across a wide range (0,030-0,798). This adaptability allows for the adjustment of the mortar mixture's rheological behaviour throughout a spectrum ranging from «abnormally viscous liquid» to «Newtonian liquid». This approach, examining the singular-factor dependencies' analysis on the coefficients of rheological behaviour models, aids in addressing the primary challenge encountered when using concrete with lightweight aggregate.