# Application of FA-CGP-GGBS Geopolymers as Cement Substitute in Crushed Stone Base

## TL;DR

This study explores using geopolymers made from industrial byproducts as a cement substitute in crushed stone bases, showing improved strength and durability.

## Contribution

A new method for utilizing coal gangue, fly ash, and slag in geopolymer mixtures for construction is proposed.

## Key findings

- Geopolymer mixtures showed 7.58% higher unconfined compressive strength than cement mixtures.
- The geopolymer system reduced harmful pores by 10% and mass loss rate by 4.29%.
- Solid waste utilization in gravel-based systems is demonstrated as a viable and improved alternative to cement.

## Abstract

In this study, a geopolymer was prepared using a sodium silicate solution to enhance the activity of coal gangue powder (CGP), fly ash (FA), and granulated blast furnace slag powder (GGBS) for replacing cement in the crushed stone base. The unconfined compressive strength, splitting tensile strength, water stability, and erosion resistance of geopolymers containing precursor contents (5%, 6%, 7%) were analyzed, and the reaction mechanism was systematically studied in combination with MIP, SEM, XRD, and TG. The cement content was 7%. The results indicate that the unconfined compressive strength and splitting tensile strength of the geopolymer mixture increased by 7.58% and 9.52%, respectively, compared with those of the cement mixture. The strength loss rate due to water stability and erosion resistance is reduced by 1.000% and 0.315%, respectively, compared with the cementitious system at the exact 7% cementitious material dosage. Compared with the cementitious system, the geopolymer system shows an 8% increase in harmless pores, a 10% reduction in harmful pores, and a 4.29% reduction in mass loss rate. This study proposes a new approach to utilizing solid waste resources and provides a theoretical basis for its application in gravel-based systems.