Characterization of alkali activated geopolymer mortar doped with MWCNT

Abstract

This paper aimed to investigate the effect of MWCNTs on properties of slag geopolymeric mortar. Geopolymeric matrices containing different MWCNTs additions (0.0, 0.1, 0.2, 0.3 and 0.4% by weight of the used binder) were synthesized. The materials were prepared at water/binder ratios in the range of 0.34–0.39% depending on the amount of MWCNT; using of 6% NaOH as alkaline activation, whereas the Gelenium Ace-30 superplasticizer was used in the ratio of 1.4–2.2% from the total dry weight. Curing was performed under temperature of 40°C and 100% R.H. Results showed that the addition of MWCNTs enhanced the resulting amorphous geopolymer structure with a marked decrease in the drying shrinkage as well as water absorption specially by using 0.1% MWCNT; further increase in WCNTs addition resulted in the agglomeration of MWCNT within the matrix and, therefore, hinder the propagation of geopolymerization reaction and negatively affect the formed geopolymer structure. XRD, FTIR, and SEM of mortar nanocomposites with MWCNT concentrations of 0.1 and 0.4-wt.% confirmed an increase in amorphous geopolymer as well as CSH up to 0.1% where the individual MWCNTs spread throughout the geopolymer matrix with uniform density.