Optimization of Fly Ash–Geopolymer Concrete for Sustainable Structural Applications under Seismic Loading

Project Abstract

This study investigates the optimization of fly ash–geopolymer concrete (FA-GPC) as a sustainable alternative to conventional Portland cement concrete for structural applications subjected to seismic loading, addressing environmental impact, durability, and seismic performance. The research adopts a multi-objective optimization framework to balance mechanical strength, stiffness, ductility, durability indicators (sulfate resistance, chloride permeability, acid attack resilience), and lifecycle environmental metrics (embodied energy, CO2 emissions, and economic cost). A comprehensive experimental program evaluates FA-GPC mixes with varying ratios of fly ash, alkali activator concentration, water-to-binder ratio, and additive components (granulated blast-furnace slag, metakaolin, superplasticizers). The optimization integrates response surface methodology (RSM) and genetic algorithm (GA) to identify Pareto-optimal mix designs that maximize compressive strength and flexural performance while minimizing embodied energy and emissions, under batch and long-term curing conditions. Experimental results indicate that FA-GPC demonstrates comparable early-age strength to conventional cementitious systems, with improved long-term strength gain and enhanced resistance to autogenous shrinkage due to optimized microstructure from geopolymer polymerization. Scanning electron microscopy and X-ray diffraction reveal a denser gel matrix and reduced pore connectivity in optimized mixes, contributing to superior durability under aggressive environmental exposures. Dynamic tests, including shake-table simulations and cyclic loading, show that optimized FA-GPC specimens exhibit enhanced damping capacity, reduced residual displacements, and higher energy dissipation compared with ordinary Portland cement concrete under similar seismic demands. Finite element models calibrated with experimental data demonstrate that structures employing the optimized FA-GPC exhibit improved base shear capacity, reduced peak floor accelerations, and greater inter-story drift resistance, without compromising serviceability limits. Sensitivity analyses identify key factors driving performance alkali activator modulus, fly ash fineness, and effective silica/alumina content govern geopolymerization kinetics and microcrack propagation under cyclic loads. Durability tests reveal that optimized FA-GPC maintains mechanical integrity after exposure to sulfate and chloride-rich environments, indicating superior lifecycle performance in aggressive geological settings. Life cycle assessment (LCA) indicates substantial reductions in embodied energy and CO2 emissions for FA-GPC mixes relative to conventional concrete, with comparable or lower total cost over the building life cycle due to reduced maintenance and longer service life. The study also assesses practical considerations for field deployment, including workability, curing requirements, and compatibility with reinforcing steels, proposing a pragmatic mix design protocol for seismic-resistant, sustainable structures. The findings support FA-GPC as a viable, greener alternative for seismic-resistant foundations and frames, offering a pathway to meet stringent performance, sustainability, and regulatory criteria in modern civil infrastructure.

Project Overview

What This Project Is About

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A practical study of using fly ash–geopolymer concrete to build safer, more sustainable structures that perform well during earthquakes. The project looks at materials, mix design, and how these concretes react to shaking compared with ordinary concrete.

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The Problem It Addresses

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Objectives of the Project

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1. Understand the basic properties of fly ash–geopolymer concrete.
2. Develop mix designs that balance strength, toughness, and workability.
3. Evaluate seismic performance through simple simulated tests.
4. Compare performance with conventional concrete.
5. Identify practical guidelines for sustainable structural use.

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What You Will Do Step by Step

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1) Review background literature; 2) source fly ash and binders; 3) prepare several mix designs; 4) test fresh properties (workability, flow); 5) cast and cure specimens; 6) perform mechanical tests (compressive strength, modulus, toughness); 7) conduct basic simulated seismic tests; 8) analyze data and compare with traditional concrete; 9) draft practical recommendations.

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Expected Outcome

Anticipate a viable mix design that offers lower environmental impact and adequate seismic performance, with guidelines for use in affordable, sustainable construction.