Effect of Water Addition on Gel-Forming Capacity and Structure–Property Evolution of Water-Reactive Polyurethane Grout
- 1School of Engineering and Technology, China University of Geosciences (Beijing), Beijing 100083, China
Abstract
Water-reactive polyurethane (PU) grout is widely used for water sealing, yet its gel-forming capacity and property evolution under uncontrolled water addition remain insufficiently understood. In this study, PU:water volume ratios from 1:1 to 1:20 were investigated using gelation tests, Shore OO hardness and uniaxial compression tests, SEM, ATR-FTIR, and non-reactive all-atom molecular dynamics simulations. Increasing water addition prolonged the gelation time from approximately 15 s at PU:water = 1:1 to 22 s at 1:15. Stable gel formation was maintained up to a water-addition multiple of 18× (PU:water = 1:18, v/v), whereas stable gel formation failed at multiples of 19× and 20×. Meanwhile, the Shore OO hardness decreased from approximately 63 to 2, and the compressive stress at 50% strain decreased from 208 to 8 kPa between PU:water = 1:1 and 1:15. SEM revealed increasingly heterogeneous and locally loose pore structures at high water contents. ATR-FTIR confirmed substantial consumption of free –NCO groups and changes in the carbonyl/amide region after curing. MD simulations further showed composition-dependent changes in local water distribution and hydrogen-bond participation before reaction. These results establish the water-tolerance boundary and multiscale property evolution of water-reactive PU, providing a basis for controlling PU–water proportions in water-rich grouting applications.
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BibTeX
@article{qi2026effect,
title = {{Effect of Water Addition on Gel-Forming Capacity and Structure–Property Evolution of Water-Reactive Polyurethane Grout}},
author = {Bowen Qi and Xinhua Chen and Langtian Qin and Feng Huang},
journal = {Polymers},
year = {2026},
month = nov,
doi = {10.3390/polym18212731},
url = {https://www.mdpi.com/2073-4360/18/21/2731},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Effect of Water Addition on Gel-Forming Capacity and Structure–Property Evolution of Water-Reactive Polyurethane Grout
AU - Bowen Qi
AU - Xinhua Chen
AU - Langtian Qin
AU - Feng Huang
PY - 2026
DA - 2026/11/03
JO - Polymers
DO - 10.3390/polym18212731
UR - https://www.mdpi.com/2073-4360/18/21/2731
AB - Water-reactive polyurethane (PU) grout is widely used for water sealing, yet its gel-forming capacity and property evolution under uncontrolled water addition remain insufficiently understood. In this study, PU:water volume ratios from 1:1 to 1:20 were investigated using gelation tests, Shore OO hardness and uniaxial compression tests, SEM, ATR-FTIR, and non-reactive all-atom molecular dynamics simulations. Increasing water addition prolonged the gelation time from approximately 15 s at PU:water = 1:1 to 22 s at 1:15. Stable gel formation was maintained up to a water-addition multiple of 18× (PU:water = 1:18, v/v), whereas stable gel formation failed at multiples of 19× and 20×. Meanwhile, the Shore OO hardness decreased from approximately 63 to 2, and the compressive stress at 50% strain decreased from 208 to 8 kPa between PU:water = 1:1 and 1:15. SEM revealed increasingly heterogeneous and locally loose pore structures at high water contents. ATR-FTIR confirmed substantial consumption of free –NCO groups and changes in the carbonyl/amide region after curing. MD simulations further showed composition-dependent changes in local water distribution and hydrogen-bond participation before reaction. These results establish the water-tolerance boundary and multiscale property evolution of water-reactive PU, providing a basis for controlling PU–water proportions in water-rich grouting applications.
SN - 2073-4360
ER -