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871 results on '"Hou, Dongshuai"'

301. Two-scale modeling of the capillary network in hydrated cement paste

Author

Ma, Hongyan, Hou, Dongshuai, Lu, Youyuan, and Li, Zongjin

Subjects
Cement -- Usage -- Properties -- Analysis, Hydrates -- Usage -- Properties -- Analysis, Business, Construction and materials industries
Abstract

ABSTRACT Objective: Studies on pore structure are essential to better understand the transport properties and durability of cement based materials. In this study, a two-scale modeling framework is proposed to [...]

Published
2014
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318. Understanding the filling effect of ice on the mechanical properties of calcium silicate hydrate gel

Author

Chai, Songyue, Zheng, Heping, Hou, Dongshuai, Wang, Muhan, Zhang, Yue, Yin, Bing, and Wang, Pan

Abstract

Ice exhibits good mechanical performance at low temperatures, and when it replaces the weakest pores in cement-based materials, it can noticeably enhance the overall mechanical properties of the material. However, the specific micro-mechanisms that contribute to the improvement of tensile mechanical properties in gel pores at low temperatures are still not fully understood. Based on the results of molecular dynamics simulations, significant roles have been attributed to pore size and temperature in the mechanical performance of gel pores at low temperatures. A thorough investigation was conducted on the process of tensile failure in saturated gel pores, as well as the changes in bonding interactions between calcium silicate hydrate (CSH)-ice and the unfrozen water film (UWF) at different pore sizes and temperatures. The results indicate that increasing pore size and decreasing temperature can improve the mechanical properties of saturated gel pores. With the decrease in temperature, the mechanical properties of the three gel pore systems with heights of 100 Å, 68 Å, and 54 Å were significantly enhanced. Under an engineering strain rate of 8×10−4/ps, the tensile strength and elastic modulus of gel pores increased from 0.57 GPa and 17.81 GPa at 250 K, to 0.97 GPa and 20.87 GPa at 150 K, respectively. To explain this phenomenon, further studies were conducted on the radial distribution function and dynamic hydrogen bonding behavior. The critical contribution of the hydrogen bond network to the mechanical performance of gel pores was discovered. The hydrogen bond structure which experienced the earliest damage, was investigated. As the strain increased, the hydrogen bonds continuously broke and reformed. This research provides a theoretical understanding of the mechanical properties of gel pores under low-temperature conditions.

Published
2024
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319. A polystyrene acrylate-polysiloxane multicomponent protective coating with interpenetrating polymer network structure for cementitious materials.

Author

Wu, Cong, Hou, Dongshuai, Yin, Bing, Chen, Binmeng, and Li, Zongjin

Subjects
*THERMODYNAMICS, *MOLECULAR structure, *POLYMER networks, *CHEMICAL bonds, *PROTECTIVE coatings, *PHASE separation
Abstract

The polystyrene acrylate (PSA) coating and polysiloxane coatings can protect the durability of cementitious materials through surface barrier and internal hydrophobicity, respectively. However, their composite coating presents a challenge due to the significant difference in molecular structure, molecular polarity, and thermodynamic properties, leading to poor interfacial compatibility. This paper presents a novel multi-component interpenetrating polymer network (IPN) based on the 'host - guest molecular structure' theory, which consists of cross-linked PSA as the main molecule and polysiloxane as the guest molecule, interfacially regulated by functionalized nanoparticles. The IPN composite coatings with high microphase separation properties enable dual synergistic protection of the durability of cementitious materials. The IPN emulsions synthesized increased the proportion of harmless pores within the cementitious materials to over 88.3 %. Additionally, they decreased the static capillary water absorption of concrete by over 94.06 % and effectively inhibited the formation of corrosion products, including Friedel's salt, gypsum, ettringite, and CaCO 3. The adhesion strength of the IPN coating was also improved to 2.7 MPa, and its thermal expansion coefficient was limited to within 5.5 × 10−5/K. Moreover, the modified IPN coating contains numerous strong hydrogen bonds and interwoven molecular networks. These features enable stable deformation recovery and surface shielding of cracked concrete. • We designed a PSA - polysiloxane composite coating with IPN structure. • Functionalized nanoparticles regulate the host - guest molecular interface. • IPN coatings provide superior waterproofing and resistance to ionic attack. • Interfacial adhesion strength of IPN coatings exceeds 2.7 MPa. • Strong hydrogen bonding exists within the modified IPN coating. [ABSTRACT FROM AUTHOR]

Published
2024
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350. Frost resistance and sustainability of seawater-mixed sintered sludge cement paste

Author

Lv, Tong, Zhang, Jinrui, Hou, Dongshuai, Long, Wu-Jian, and Dong, Biqin

Abstract

Due to a loose and porous structure, the addition of sintered sludge ash (SSA) in large amounts often leads to a decrease in durability. To address the issue, a systematic investigation is conducted into the combined effects of seawater and SSA (0∼50%) on cement paste. The mixing of seawater enhances the improvement effect of 10% SSA on frost resistance and capillary water absorption. Meanwhile, the seawater-mixed cement paste containing 30% SSA withstands 125 freeze-thaw cycles, superior to PC. After seawater mixing, SSA performs better in terms of the generation of high-density C–S–H gel. The promoting effect of SSA on the transformation of capillary pores into gel pores in cement paste and its content threshold are amplified. The chemical binding of Cl−and SO42−with amorphous Al2O3in SSA promotes the conversion of AFt to AFm. Additionally, based on multi-criteria analysis, the seawater-mixed sintered sludge cement is more competitive.

Published
2024
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