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Insights on hydrolysis weakening of calcium silicate hydrate：
a ReaxFF molecular dynamics study

HOU Dongshuai，YU Jiao，ZHANG Jinrui，ZHANG Mengxi，DONG Biqin
（1. School of Civil Engineering，Qingdao University of Technology，Qingdao 266000，China；
2. State Key Laboratory of Hydraulic Engineering Simulation and Safety，Tianjin University，Tianjin 300072，China；
3. Guangdong Province Key Laboratory of Durability for Marine Civil Engineering，Shenzhen University，Shenzhen 518060，China）

Abstract：Calcium silicate hydrate （C-S-H） gel is the main cementing phase of concrete materials，the hy⁃
drolysis weakening of which is an important reason for the failure of concrete materials and the decrease of
cementing force. In this paper， the effects of water content on molecular structure and mechanical proper⁃
ties of C-S-H gel are studied by molecular dynamics simulation （ReaxFF） The penetration of water mole⁃
.
cules accelerates the translational motion of the calcium silicate skeleton， which is directly related to the
decrease of the stability of the whole structure. The results show that the un-bridging oxygen in the silicon
chain of C-S-H with high reactivity is helpful to hydrolysis reaction. Hydroxyl groups generated by hydroly⁃
sis reaction and water molecules form a complex H-bonds network in the C-S-H interlayer region， which
gradually transfers the weak area of the structure from the intralayer to the interlayer region and reduces
the rearrangement degree of the silicon chain in the uniaxial tension process. With the increase of water
content，more structures with defect appear in C-S-H，leading to the decrease of mechanical properties of
C-S-H gel.
Keywords：calcium silicate hydrate；molecular dynamics；reactive force field；hydrolysis reaction；dynamic
properties
（责任编辑：王冰伟）

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