Response of self-compacting paste (SCP) systems containing Acacia Modesta gum

This paper shows the response of self-compacting paste systems (SCPs) containing botanical Acacia Modesta (AM) gum, a natural organic ooze-out of an indigenous tree called Phulai, as an admixture. The gum being different in its nature and origin, exhibited different results from Acacia Nilotica gum powder when used in SCPs. AM gum powder was characterized by X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). The self-compacting paste systems (SCPs) containing 0.25%, 0.5%, 0.75% and 1% AM gum powder were tested for super-plasticizer (SP) demand, flow, viscosity, air content (in fresh state), density, total linear early shrinkage, calorimetry and both short-term (28-day) and long-term (90-day) compressive strengths. SCPs with AM gum powder showed a considerable decrease in total shrinkage, a reduction in density values, an increase in fresh state viscosity. AM gum powder also had a retarding effect on setting times of the respective gum modified SCPs. Moreover, the electrical resistivity of samples containing AM increased tremendously indicating change in the microstructure of the gum modified SCP systems. It became clear that different types of Acacia gums when incorporated in SCPs gave different responses and should be used with complete understanding. Therefore, AM gum in cementitious systems offers many potential areas for application and further future research work. The AM gum powder may be used for reducing shrinkage in SCP systems, establishing internal curing inside the SCCS, for enhancing the viscosity of the cementitious systems and for producing slightly porous energy efficient cementitious systems.