A Study Of Self-Compacting Paste Systems Using Acacia Modesta Gum As An Admixture

Abstract

This study presents response of self-compacting paste systems containing botanical Acacia Modesta (AM) gum, a natural organic ooze-out of an indigenous tree called Phulai, as an admixture. AM gum’s crystallography was performed through X-ray Diffraction (XRD). It was chemically characterized through X-ray Fluorescence (XRF), Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). The behavior of AM gum in water and varying temperatures was also tested. These characterization tests showed that AM gum is composed mainly of hydrophobic components and therefore it behaves as a nearly inert material in self-compacting cementitious systems. The Self-compacting paste systems (SCPs) containing 0.25 %, 0.5 %, 0.75 % and 1 % powdered gum of total dry cement weight were tested for super-plasticizer demand, flow, viscosity and air voids in fresh state and for density, total shrinkage, calorimetry and 90-day compressive strength. The results showed a decrease in total shrinkage by 41 %, a reduction in density by 21 %, an increase in viscosity and a progressive delay in setting time of the respective gum based SCPs. Moreover, the gum seemed to behave as an internal curing agent. The incorporation of AM gum therefore exhibited several potential fields of application in self-compacting cementitious systems. This research offers potential applications in thermally efficient freeze-thaw resistant light weight concrete constructions.