Numerical simulation on moisture transport from super absorbent polymers to concrete

Title: Numerical simulation on moisture transport from super absorbent polymers to concrete
Author(s): H. Huang, G. Ye, K. van Breugel
Paper category : conference
Book title: 2nd International Symposium on Service Life Design for Infrastructures
Editor(s): K. van Breugel, Guang Ye, Yong Yuan
Print-ISBN: 978-2-35158-096-7
e-ISBN: 978-2-35158-097-4
Publisher: RILEM Publications SARL
Publication year: 2010
Pages: 185 - 194
Total Pages: 10
Nb references: 16
Language: English

Abstract: Self-healing of the cracks in concrete can be promoted when some extra water is available.
This can be contributed to the further hydration of unhydrated cement and the formation of calcium carbonation. In this research, the superabsorbent polymers (SAPs) were employed to store extra water for self-healing. After being saturated, SAPs were sealed by water-proof material and premixed with cement. When the concrete cracked, the cracks passed through the SAP capsules due to the low strength of SAP. The water stored inside the SAP capsules was released into the crack and transported into the concrete.
The moisture transport from SAPs into concrete includes three physical processes: water desorption of SAPs, moisture diffusion inside the cracks and the moisture transport from the cracks into concrete. In this contribution, these physical processes were simulated by finite difference method. From the modeling results, it was found that the desorption rate of the SAP capsules inside concrete was about 0.35 g/m2min. When the SAP capsules were broken by the cracks, the moisture desorbed from SAPs filled the cracked immediately. At the same time, the moisture transport from the cracks into the concrete took place due to the humidity gradient. It takes about 10 minutes for the relative humidity to rise from 82.5% to 99.5%. The moisture content and penetration depth into concrete in different time after the capsule was opened were also calculated. It was found that the water content of the concrete close to the crack surfaces rises immediately after the capsule was broken. The penetration depth of the extra water into concrete is 1.5 mm in the 2nd hour after the capsule was broken, while 2 mm in the 48th hour when the degree of saturation of concrete is 0.25 and the porosity is 0.2.

Online publication: 2011-04-20
Publication type : full_text
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