Title: Cracking Control of Mass Concrete Slab in Nuclear Power Plant with Dynamic Curing

Author(s): Zhang Xingbin, Rong Hua, Zhang Zhong, Fang Sha, and Geng Yan

Publication: Materials Journal

Volume: 119

Issue: 3

Appears on pages(s): 39-52

Keywords: active thermal stress control; cracking control; dynamic curing; elastic strain monitoring; mass concrete slab

DOI: 10.14359/51734602

Date: 5/1/2022

Abstract:
To control cracking of mass concrete slabs in nuclear power plants (NPPs), a dynamic curing technique is proposed based on the stress superposition principle and elastic assumptions. It optimizes the stress field through targeted regulation of temperature variation according to the measured elastic strain εem by flexible application of surface-protection techniques. The limit tensile strain of εem is defined as 120 με to guarantee no cracks would occur. In its application on two slabs, only one hairline vertical crack was observed when εem reached 130 με on the 12th day after casting. However, the tensile strain gradually decreased, and the crack tended to close with age. The presented technique has been verified on more than 20 NPPs throughout the continuous casting stage (and even the operation period), saving construction time in the meantime. In addition, it provides theoretical and technical guidance for further investigation of mass concrete with complicated cross-section shapes.