# Dual-Functional Utilization of Phosphogypsum as Cementitious Binder and Aggregate in Concrete: Interfacial Compatibility and Feasibility Analysis

## TL;DR

This study explores using phosphogypsum as both a cement binder and aggregate in concrete to reduce waste and create sustainable building materials.

## Contribution

The paper introduces a dual-functional utilization strategy for phosphogypsum, focusing on interfacial compatibility and mechanical performance.

## Key findings

- The dual-functional PG formulation achieved a 38% mass incorporation rate with compressive strength of 39.3 MPa.
- PG-binder/PGA systems showed better interfacial bonding than PG-binder/stone systems.
- The interfacial transition zone formed interwoven ettringite and C-S-H gel networks, enhancing structural integration.

## Abstract

Addressing the environmental challenges posed by phosphogypsum (PG) stockpiling, this study investigates the synergistic mechanisms of a dual-functional application strategy where PG serves as both cementitious binder and aggregate. Unlike previous research limited to single-mode utilization, this study focuses on the interfacial compatibility between PG-based binders and PG aggregates (PGA). Through a comparative experimental program, the mechanical performance and microstructure of different binder–aggregate combinations were evaluated. The proposed dual-functional formulation achieved a high PG incorporation rate of 38% by mass. While the compressive strength of 39.3 MPa was lower than that of the reference ordinary concrete, it comfortably surpasses the C30 strength requirement for structural applications, validating its engineering feasibility. Comparative analysis revealed that although natural stone aggregates possess higher intrinsic strength, the PG-binder/PGA system exhibits superior interfacial bonding compared to the PG-binder/stone system. Microstructural observations indicated that this synergistic interaction facilitates the formation of interwoven ettringite and C-S-H gel networks, contributing to a structurally integrated interfacial transition zone (ITZ). These findings suggest that the dual-functional strategy offers a viable pathway for developing low-carbon building materials by balancing high-volume waste utilization with mechanical compliance.