Investigating the influence of various metakaolin combinations with different proportions of pond ash and Alccofine 1203 on ternary blended geopolymer concrete at ambient curing.

This paper explores the use of a ternary blended geopolymer concrete (TBGPC) incorporating metakaolin (MK), pond ash (PA), and Alccofine 1203 (AF). Three combinations of MK (25%, 50%, and 75%) with varying proportions of PA and AF were prepared, validating against M grade cement concrete (CC). TBGPC was prepared with an 8 molarity sodium hydroxide, sodium silicate to sodium hydroxide ratio of 2.0, liquid to binder ratio of 0.5, and an ambient curing mode. For CC, a water to cement ratio of 0.42 and water curing mode were adopted. The mechanical properties and durability behavior of TBGPC and CC specimens were evaluated through compressive strength, rapid chloride penetration test, permeability test, sorptivity test, and water absorption test. The MPA mix demonstrated remarkable compressive strength improvements, showing a 203% increase over the CC mix at 1 day and 250% by 3 days. This trend continued with a 155% increase at 7 days, 68% at 28 days, and 52% at 90 days, consistently outperforming the CC mix. Additionally, microstructure characteristics of the MPA mix were analyzed through SEM studies, providing validation for the observed strength development. Notably, MPA mix demonstrated substantially higher early and later strength gain. This enhancement in strength was attributed to the gradual densification of the microstructure over time and the formation of additional NASH and CASH gel in MPA mix. At 28 days, the MPA mix exhibited excellent durability characteristics, with a Coulomb value of 1008, permeability of 10 mm, sorptivity of 0.45 mm/√min × 10, and water absorption of 1.07%. This study demonstrates the potential of MK, PA, and AF as viable materials for sustainable geopolymer concrete, offering a low-carbon alternative to traditional cement concrete with superior strength and durability aspects.