Abstract
The construction industry, integral to national infrastructure development, faces environmental
challenges attributed to Portland cement’s high energy consumption and carbon dioxide
emissions during production. To address this challenge, this study integrated waste fly ash and
polystyrene into geopolymers to enhance environmental sustainability and economic feasibility. The
objectives included developing low-density geopolymers using polystyrene inclusion, optimizing
component mixing ratios, assessing activator concentration effects, determining the optimal curing
conditions, and characterizing the resulting geopolymers. Through experimental investigation,
low-density geopolymers were developed with optimized component ratios and curing conditions.
The experimental procedure began with the classification of fly ash to determine its suitability for
various applications, revealing it to be type F. Geopolymers were fabricated using a mixture of fly
ash, water, sodium hydroxide activator, and polystyrene. Varied concentrations of sodium hydroxide
and polystyrene were employed. Two curing temperatures, 60 ◦C and 100 ◦C, were explored. The
results showed that greater sodium hydroxide concentrations improved the structure and compressive
strength of the geopolymers. The results also demonstrated a significant correlation between
the curing conditions and the mechanical properties of the produced geopolymers. The goal of
reducing the density of the geopolymers for lightweight thermal-resistant applications was achieved
through polystyrene incorporation. However, polystyrene incorporation negatively impacted the
compressive strength. The optimum production conditions for the sodium hydroxide-varied samples
were 8 g sodium hydroxide/g sample cured at 100 ◦C, while the optimum production conditions for
polystyrene-varied samples were 1 g polystyrene/g sample cured at 60 ◦C. The findings confirmed
the viability of utilizing fly ash and polystyrene wastes to produce sustainable, low-density, thermalresistant
construction materials. Overall, increasing activator concentration enhances the strength
and durability of geopolymers, while polystyrene contributes to the development of lightweight
geopolymers, provided the appropriate amount is utilized. To ensure replicability, the formulation
procedure and input quantities must be tailored according to the intended geopolymer application.
These insights offer practical guidance for optimizing geopolymer manufacturing processes towards
enhanced sustainability and performance.