Abstract

Geopolymer binders are created by mixing precursors rich in silica (Si) and aluminium (Al), such as fly ash and ground granulated blast furnace slag (GGBS), with specific amounts of alkaline reagents like sodium or potassium silicates and hydroxides. This study aimed to develop geopolymer concrete suitable for pavement quality concrete (PQC) by utilizing fly ash and GGBS as precursors, combined with sodium silicate (Na₂SiO₃) and sodium hydroxide (NaOH) as alkaline reagents. Two different mixes were prepared using a fly ash to GGBS ratio of 75:25 and 60:40. Each mix was subjected to two types of curing conditions: one group of specimens was completely sealed with 100-micron thick plastic sheets and stored at room temperature, while the other group was left exposed without any plastic covering. Research was conducted on the mechanical strength, sorptivity, amount of non-evaporable water, and the microstructure of the concrete specimens. The findings revealed that the sealed specimens exhibited lower sorptivity, higher compressive strength, and retained a greater amount of non-evaporable water compared to the open-cured specimens. Sealing the concrete effectively prevented the loss of surface water, thereby minimizing the formation of air voids on the surface and promoting the retention of a greater amount of inbound water. The microstructure of the sealed concrete specimens was denser, more compact, and contained a higher Silica to Alumina (Si/Al) content compared to the open-cured specimens.

Keywords

Geopolymer concrete, Sealed curing, Fly ash, Ground granulated blast furnace slag (GGBS), Mechanical and microstructural properties, Sustainable construction materials.

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