Effects of micro-structure characteristics of interfacial transition zone on the compressive strength of self-compacting geopolymer concrete

This paper presents an experimental study of the influence of different superplasticizer dosage on compressive
strength and micro-structure characteristics of interfacial transition zone (ITZ) prepared with fly
ash based self-compacting geopolymer concrete (SCGC). The correlations between compressive strength
development and microstructure of interfacial transition zone were also investigated. Concrete specimens
were prepared with different superplasticizer (SP) dosage namely 3%, 4%, 5%, 6% and, 7% and cured
at 70 �C for duration of 48 h. Field emission scanning electron microscope (FESEM) observations revealed
that improved performance of concrete was found when the compressive strength increased through formation
of dense ITZ between the aggregate and binder matrix at higher SP dosage. There are good correlations
between compressive strength and micro-structure characteristics of interfacial transition
zone. The FESEM analysis revealed that relatively a loose and porous interfacial zone was found between
the binder and aggregate for low SP dosage and theses loose and porous ITZ decreased the performance of
concrete by lowering the compressive strength; however, a dense ITZ was found between the aggregate
and binder matrix for higher SP dosage that enhanced the concrete performance by increasing the compressive
strength.