Alternative Repair Material Made from Fly Ash-Portland Concrete-Commercial Repair Geopolymers
This research aims to study the setting time and compressive strength of geopolymer mortar from fly ash (FA)
containing Portland cement (PC) and commercial repair mortar (RM). Geopolymer binder is manufactured from FA and PC at
ratio of 70:30 by weight of binder. The PC:RM ratios are used at 30:0, 20:10, 15:15, 10:20 and 0:30 by weight of binder.
Sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) solutions are used as the liquid portion in all mixes. The difference
in NaOH concentrations of 5, 10 and 15M has been investigated. Test results reveal that high amount of PC in a mixture has
effect on setting time and compressive strength than that of RM. While, increase in NaOH concentration could delay the setting
time of FA-PC-RM geopolymers. Also, compressive strength of FA-PC-RM geopolymers tends to decrease with increasing
NaOH concentration. The use of 20wt%PC and 10wt%RM with 10M NaOH give the optimum compressive strength of
FA-PC-RM geopolymers. In addition, they meet the minimum strength requirements for repair binder as per ASTM standard.