Work

Systematic Evaluation of Concrete Placement Reliability in Heavily Reinforced Nuclear Structures

Year: 2026

Type: article

Abstract: Concrete placement in nuclear power plant (NPP) structures is challenged by severe reinforcement congestion and complex internal geometries, where conventional slump-based workability control may not reliably predict placement performance. This study investigates the relationship between polycarboxylate ether-based admixture (PCE) adsorption, rheological behavior, and placement performance through a multiscale experimental program. Conventional workability tests (slump, L-box, and U-box), PCE adsorption analysis using total organic carbon (TOC), rheological characterization, and custom-fabricated placement simulation tests were performed. The results showed that mixtures with similar slump values exhibited significantly different passing behavior due to differences in PCE adsorption and resulting rheological properties. A clear relationship between yield stress and blockage risk was identified using a vertical drop test, indicating that mixtures with paste yield stress exceeding approximately 0.3 Pa exhibited reduced discharge and a high risk of blockage under reinforced congestion. A horizontal filling test further demonstrated that horizontal placement represents a more severe condition than vertical passing, as even highly flowable concrete could not achieve complete void-free filling along extended horizontal paths under self-weight.

Source: International Journal of Concrete Structures and Materials

DOI: 10.1186/s40069-026-00964-8