Nondestructive measurement of the capillary water absorption coefficient and water transport behaviors of porous building materials by using single-sided NMR

• Published in: Construction & building materials Vol. 414; p. 134819
• Main Authors: Long, Zhenyu, Zhang, Zhongjian, Zhang, Hao
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 02.02.2024
• Subjects: Capillary absorption coefficient; Nondestructive measurements; Porous building materials; Single-sided nuclear magnetic resonance; Water transport model; Nondestructive measurements; Single-sided nuclear magnetic resonance; Porous building materials; Water transport model; Capillary absorption coefficient
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2023.134819

Capillarity has an important effect on the durability of buildings, and the capillary absorption coefficient is a key parameter to describe the strength of material capillarity. Most of the methods currently used to measure the capillary absorption coefficient of materials can damage the sample or are not accurate enough and need to be improved. This paper proposes a method to measure the capillary absorption coefficient of brick, sandstone, mortar and concrete by using a single-sided nuclear magnetic resonance (NMR) technique, which has the advantages of accuracy, nondestructiveness, continuity and rapidity. The relative error of the capillary absorption coefficient obtained from three repetitions of the experiment ranges from 0 to 5.11%, which is in the range of 0.64%∼1.30% compared with that obtained by the partial impregnation method. This method has great potential for application in in situ testing. This paper also analyzed the water transport behaviors in porous building materials based on the variation in NMR signal intensity in the measured materials and established a water transport model. The model is divided into two stages: the first stage is mainly the one-dimensional rise in moisture in the vertical direction. The second stage is mainly the diffusion of moisture in the horizontal direction, which continuously fills each pore space to saturation. Difficulty in removing air leads to a reduced rate of water absorption in the second stage. •A method is presented for measuring capillary absorption coefficients of porous building materials using single-sided NMR.•The water absorption behavior of porous building materials was analyzed.•A water absorption model is proposed for porous building materials.•The feasibility of conducting in situ measurements using single-sided NMR is discussed.