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Dr. Hailong Ye
Department of Civil Engineering, The University of Hong Kong, Hong Kong, China

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0 geopolymers
0 Durability of Concrete
0 alkali-activated materials
0 Cement Chemistry
0 Microstructure characterization

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Corrosion of steel in concrete
geopolymers
Ultra-high-performance concrete

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Journal article
Published: 17 June 2021 in Construction and Building Materials
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Ultra-high performance concrete (UHPC) shows volumetric instability at high temperatures because of explosive spalling. Polypropylene (PP) fibers are effective in mitigating the explosive spalling of UHPC; however, the threshold PP fiber dosage to prevent explosive spalling of UHPC remains unascertained. In this work, a knowledge-enhanced data-driven machine learning method is proposed to quantify the effectiveness of PP fibers in preventing fire-induced spalling of UHPC. Based on the knowledge-enhanced technique, the training data size is increased from 244 to 1642. The prediction accuracy of the artificial neural network (ANN) and extreme gradient boosting (XGBoost) models on 54 groups of unseen data is increased by more than 10% after the training data augment. The well-validated ANN model is then used to determine the threshold PP fiber dosage of UHPC tunnel lining under hydrocarbon fire conditions. The analysis results show that as high as 3.5 kg/m3 PP fibers are required to eliminate explosive spalling of UHPC, but this critical dosage can be lowered to 2.5 kg/m3 by limiting the silica fume replacement level.

ACS Style

Jin-Cheng Liu; Le Huang; Zushi Tian; Hailong Ye. Knowledge-enhanced data-driven models for quantifying the effectiveness of PP fibers in spalling prevention of ultra-high performance concrete. Construction and Building Materials 2021, 299, 123946 .

AMA Style

Jin-Cheng Liu, Le Huang, Zushi Tian, Hailong Ye. Knowledge-enhanced data-driven models for quantifying the effectiveness of PP fibers in spalling prevention of ultra-high performance concrete. Construction and Building Materials. 2021; 299 ():123946.

Chicago/Turabian Style

Jin-Cheng Liu; Le Huang; Zushi Tian; Hailong Ye. 2021. "Knowledge-enhanced data-driven models for quantifying the effectiveness of PP fibers in spalling prevention of ultra-high performance concrete." Construction and Building Materials 299, no. : 123946.

Journal article
Published: 01 May 2021 in Cement and Concrete Composites
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In this work, a clinkerless alkali-activated slag-based ultra-high strength concrete (AAS-UHSC) with tailored mix proportions was developed at room temperature. To evaluate its practical serviceability, a systematic investigation was conducted on the fresh and mechanical properties (compressive, splitting tensile, and flexural strengths), with an emphasis on the uniaxial compressive behavior of AAS-UHSC subject to repeated loading and elevated temperatures. The results showed that despite the fast setting of AAS-UHSC, a significant improvement in flowability could be obtained with a slight increase in water-to-binder ratio. Regarding the strength development during the curing period, a higher early compressive strength was observed for AAS-UHSC when compared with ordinary Portland cement (OPC)-based UHSC, but a contrary behavior was found for the evolution of splitting tensile strength. Moreover, relative to the fiber-free AAS-UHSC, great improvements up to 31 times and 2.5/4.3 times in the flexural fracture energy and monotonic/cyclic compressive toughness were achieved for the specimens containing 1.5% steel fiber by volume, respectively. The superior high-temperature performance of AAS-UHSC free of explosive spalling could be attributed to its intensive shrinkage cracking upon dehydration, which likely leads to a significant enhancement of pore connectivity as the exposure temperature increases.

ACS Style

Le Huang; Jin-Cheng Liu; Rongjin Cai; Hailong Ye. Mechanical degradation of ultra-high strength alkali-activated concrete subjected to repeated loading and elevated temperatures. Cement and Concrete Composites 2021, 121, 104083 .

AMA Style

Le Huang, Jin-Cheng Liu, Rongjin Cai, Hailong Ye. Mechanical degradation of ultra-high strength alkali-activated concrete subjected to repeated loading and elevated temperatures. Cement and Concrete Composites. 2021; 121 ():104083.

Chicago/Turabian Style

Le Huang; Jin-Cheng Liu; Rongjin Cai; Hailong Ye. 2021. "Mechanical degradation of ultra-high strength alkali-activated concrete subjected to repeated loading and elevated temperatures." Cement and Concrete Composites 121, no. : 104083.

Journal article
Published: 22 April 2021 in Cement and Concrete Research
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This work investigates the degradation mechanisms of clinkerless alkali-activated slag based ultra-high strength concrete (AAS-UHSC) upon exposure to high temperatures up to 800 °C. The heat-induced mechanical, mineralogical, molecular, microstructural, and pore structure alterations of AAS-UHSC prepared with various activator types, water-to-powder ratios, and fiber incorporation are studied. The results demonstrate the beneficial roles of potassium incorporation on improving the thermal stability and integrity of AAS-UHSC, via suppressing deleterious crystallization and transformation of aluminosilicate phases at high temperature. In contrast to Portland cement clinker-based UHSC, no sign of explosive spalling is observed in AAS-UHSC, likely due to the presence of microcracks that enhance the pore network connectivity. The mechanical degradation of AAS-UHSC at high temperature below 600 °C is resulted from dehydration and decomposition of phases and consecutive thermal cracking, together with enlarged porosity and coarsened pore structure. As the temperature rising to 800 °C, crystallization and transformation of phases, as well as formation of porous microstructure, considerably aggravate the mechanical degradation of AAS-UHSC. In contrast to the thermal damage mitigation by polymeric fibers in conventional UHSC, the fiber incorporation has little positive impact on the thermal resistance of AAS-UHSC.

ACS Style

Rongjin Cai; Hailong Ye. Clinkerless ultra-high strength concrete based on alkali-activated slag at high temperatures. Cement and Concrete Research 2021, 145, 106465 .

AMA Style

Rongjin Cai, Hailong Ye. Clinkerless ultra-high strength concrete based on alkali-activated slag at high temperatures. Cement and Concrete Research. 2021; 145 ():106465.

Chicago/Turabian Style

Rongjin Cai; Hailong Ye. 2021. "Clinkerless ultra-high strength concrete based on alkali-activated slag at high temperatures." Cement and Concrete Research 145, no. : 106465.

Journal article
Published: 10 April 2021 in Cement and Concrete Composites
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Electrical resistivity is a key durability indicator for evaluating the mass transport properties of cementitious materials particularly in partially-saturated states. In this work, the electrical resistivity of alkali-activated slag (AAS) with and without incorporation of sodium nitrite admixture, over a broad range of relative humidity (RH), is analyzed and compared to ordinary Portland cement (OPC) pastes. The van Genuchten equation and Archie equation are used to model the dependency of electrical resistivity of AAS on RH, degree of saturation, and pore structure parameters. The results show that at relatively high RH conditions (>58%), the electrical conductivity of AAS is significantly affected by the pore structure and conductivity of pore solution. At relatively low RH (<58%) conditions, the electrical conductivity of AAS is dominantly governed by the amount of adsorption water of reacted phases. Besides, the incorporation of sodium nitrite has multiple effects on the resistivity of AAS and OPC pastes, including provision of extra conductive ions in pore solution, pore structure refinement, and improvement of the water-binding capacity of reacted phases.

ACS Style

Zushi Tian; Hailong Ye. Electrical resistivity of partially-saturated alkali-activated slag containing sodium nitrite admixture. Cement and Concrete Composites 2021, 120, 104053 .

AMA Style

Zushi Tian, Hailong Ye. Electrical resistivity of partially-saturated alkali-activated slag containing sodium nitrite admixture. Cement and Concrete Composites. 2021; 120 ():104053.

Chicago/Turabian Style

Zushi Tian; Hailong Ye. 2021. "Electrical resistivity of partially-saturated alkali-activated slag containing sodium nitrite admixture." Cement and Concrete Composites 120, no. : 104053.

Journal article
Published: 04 March 2021 in Cement and Concrete Composites
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Metakaolin has been shown to play a significant role in the pore structure evolution of cementitious materials due to its high pozzolanic reactivity and small fineness. In this work, the early-age evolution of pore structure of moderate heat Portland cement (MHPC) pastes incorporating metakaolin is studied using an innovative impedance approach. Based on the fractal modeling, the pore structure parameters of MHPC blended with metakaolin of various mass percentages up to 20%, including porosity, pore size distribution, pore tortuosity and its fractal dimension, and mean and maximal pore diameters, are determined. The results from the impedance measurements show that the porosity of metakaolin-blended MHPC at both initial hydration and pozzolanic reaction stages increases with the hydration time, which is, respectively, attributed to the dissolution of cement and metakaolin grains. The maximal porosities and the saturation states of MHPC-metakaolin blended pastes occur concurrently due to the dissolution behavior of cement grains. It is concluded that metakaolin incorporation at the 10% replacement ratio is optimal in terms of pore structure refinement of blended cement pastes.

ACS Style

Rongjin Cai; Zushi Tian; Hailong Ye; Zhen He; Shengwen Tang. The role of metakaolin in pore structure evolution of Portland cement pastes revealed by an impedance approach. Cement and Concrete Composites 2021, 119, 103999 .

AMA Style

Rongjin Cai, Zushi Tian, Hailong Ye, Zhen He, Shengwen Tang. The role of metakaolin in pore structure evolution of Portland cement pastes revealed by an impedance approach. Cement and Concrete Composites. 2021; 119 ():103999.

Chicago/Turabian Style

Rongjin Cai; Zushi Tian; Hailong Ye; Zhen He; Shengwen Tang. 2021. "The role of metakaolin in pore structure evolution of Portland cement pastes revealed by an impedance approach." Cement and Concrete Composites 119, no. : 103999.

Journal article
Published: 16 February 2021 in Cement and Concrete Research
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Intercalating the corrosion inhibitive ions in hydrotalcite is a promising approach to improve the long-term efficiency of inhibitors in corrosion protection of steel in reinforced concrete. In this work, the potential of autogenously generating nitrite- and nitrate-intercalated hydrotalcite in alkali-activated slag (AAS) is investigated. The results show that the added nitrite and nitrate ions are preferably uptaken in the interlayer structure of hydrotalcite in AAS, and the sequestered nitrite and nitrate are released upon chloride exposure in seawater and NaCl solution. The incorporation of nitrite and nitrate has little detrimental effects on the chloride binding capacity of AAS but slightly enhances the chloride ingress due to the pore coarsening effect. Similar to ordinary Portland cement (OPC), AAS is more permeable to the chloride in seawater than NaCl solution. However, unlike the release of bound chloride contributed by ettringite formation in seawater-exposed OPC, the enhanced chloride ingress in seawater-exposed AAS is primarily attributed to the aggravated pH reduction at the exposure front due to brucite formation. This study contributes to the design of alkali-activated binders with a smart inhibitor releasing ability for mitigating corrosion of steel in concrete.

ACS Style

Zhijian Chen; Hailong Ye. Sequestration and release of nitrite and nitrate in alkali-activated slag: A route toward smart corrosion control. Cement and Concrete Research 2021, 143, 106398 .

AMA Style

Zhijian Chen, Hailong Ye. Sequestration and release of nitrite and nitrate in alkali-activated slag: A route toward smart corrosion control. Cement and Concrete Research. 2021; 143 ():106398.

Chicago/Turabian Style

Zhijian Chen; Hailong Ye. 2021. "Sequestration and release of nitrite and nitrate in alkali-activated slag: A route toward smart corrosion control." Cement and Concrete Research 143, no. : 106398.

Journal article
Published: 29 January 2021 in Construction and Building Materials
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The Na2SO4-activated high-volume fly ash (Ns-activated HVFA) is a promising alternative to ordinary portland cement (OPC) due to its ecological and technical benefits. In this work, the effects of alkali dosage and silica fume incorporation on the flowability, setting time, compressive strength, porosity, composition and phase assemblage, and sulfate and acid resistance of Ns-activated HVFA are studied. The results show that an intermediate alkali dose at 2.5% by binder mass largely accelerates and enhances the strength development of HVFA. The synergic effect of Ns and silica fume further improves the strength of HVFA by about 20%. Exposure to the sodium sulfate solution can potentially promote the later activation of HVFA; while being exposed to the sulfuric acid solution, HVFA exhibits better resistance and less strength loss than the OPC-counterparts. The incorporation of silica fume negatively affects the acid resistance of Ns-activated HVFA.

ACS Style

Guojun Yang; Tong Wu; Chuanqing Fu; Hailong Ye. Effects of activator dosage and silica fume on the properties of Na2SO4-activated high-volume fly ash. Construction and Building Materials 2021, 278, 122346 .

AMA Style

Guojun Yang, Tong Wu, Chuanqing Fu, Hailong Ye. Effects of activator dosage and silica fume on the properties of Na2SO4-activated high-volume fly ash. Construction and Building Materials. 2021; 278 ():122346.

Chicago/Turabian Style

Guojun Yang; Tong Wu; Chuanqing Fu; Hailong Ye. 2021. "Effects of activator dosage and silica fume on the properties of Na2SO4-activated high-volume fly ash." Construction and Building Materials 278, no. : 122346.

Journal article
Published: 12 January 2021 in Engineering Structures
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In this work, a new mechanistic interface model is proposed to simulate the nonlinear bond behavior of steel reinforcement in concrete. With the motivations to reproduce the bond response more realistically and uncover the underlying mechanisms responsible for the high nonlinearity, the main characteristics including the damage evolution and frictional features are properly embodied during the establishment of the model. Specifically, the collective bond stress is expressed as the superposition of the mechanical interlocking and the frictional resistance, while the total reinforcement slip is first decomposed into three components, namely elastic slip, plastic slip, and sliding slip. As to the interfacial damage, by introducing a probabilistic method and the concept of cumulative slip, the irreversibility and directionality are emphatically considered. Upon these assumptions, along with mathematical and physical laws governing the developments of interfacial damage, kinematic/isotropic hardenings, and frictional sliding, the model is strictly deduced and numerically implemented within the thermodynamic framework. The numerical illustrations of the model behavior under different loading paths and the independent validations with different test results demonstrated that the proposed model is capable of reproducing the bond responses satisfactorily. The nonlinearity of the bond behavior is the integrative result of the variations of interlocking force and frictional resistance, which is largely attributed to the progressive transformation of the dominated mechanisms at different debonding stages. The presented model constitutes a beneficial addition to the understanding of the nonlinear bond behavior from the theoretical viewpoint.

ACS Style

Le Huang; Hailong Ye; Lihua Xu; Yin Chi. A mechanistic model for the nonlinear bond behavior of steel reinforcement in concrete. Engineering Structures 2021, 231, 111715 .

AMA Style

Le Huang, Hailong Ye, Lihua Xu, Yin Chi. A mechanistic model for the nonlinear bond behavior of steel reinforcement in concrete. Engineering Structures. 2021; 231 ():111715.

Chicago/Turabian Style

Le Huang; Hailong Ye; Lihua Xu; Yin Chi. 2021. "A mechanistic model for the nonlinear bond behavior of steel reinforcement in concrete." Engineering Structures 231, no. : 111715.

Research paper
Published: 06 January 2021 in International Journal of Civil Engineering
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Alkali activation of metallurgical slags produces low-carbon cementitious binders for sustainable concrete production. However, the potential deleterious reaction of internal alkalis in alkali-activated slag (AAS) with siliceous aggregates is a serious durability concern. In this work, the alkali–silica reaction (ASR) in alkali-activated ground granulated blast furnace slag mortars with various activator dosages and types, aggregate reactivity, as well as incorporation of pulverized fly ash or silica fume is studied. The ASR-induced length expansion and microstructural damage in AAS mortars are studied by a modified accelerated mortar bar test and scanning electron microscopy with X-ray energy-dispersive spectroscopy. The results show that the kinetics of ASR-induced damage, as well as the gel composition and spatial distribution, in AAS mortars is highly dependent on the alkali dosage, activator type, and aggregate reactivity. The ASR-induced length expansion is approximately proportional to the volumetric fraction of dissolved glassy aggregates. However, AAS mortars show noticeable autogenous shrinkage at the initial stage of immersion, making the conventional judgment of ASR risks using length expansion as the sole indicator invalid. The dissolution kinetics of aggregate, which is influenced by the level of alkalinity and availability of reactive silica, seems to be the rate-limiting reaction of ASR-induced damage in AAS mortars under accelerated testing conditions.

ACS Style

Le Huang; Hailong Ye. Factors Affecting Kinetics and Gel Composition of Alkali–Silica Reaction in Alkali-Activated Slag Mortars. International Journal of Civil Engineering 2021, 19, 453 -462.

AMA Style

Le Huang, Hailong Ye. Factors Affecting Kinetics and Gel Composition of Alkali–Silica Reaction in Alkali-Activated Slag Mortars. International Journal of Civil Engineering. 2021; 19 (4):453-462.

Chicago/Turabian Style

Le Huang; Hailong Ye. 2021. "Factors Affecting Kinetics and Gel Composition of Alkali–Silica Reaction in Alkali-Activated Slag Mortars." International Journal of Civil Engineering 19, no. 4: 453-462.

Journal article
Published: 01 December 2020 in Journal of Materials in Civil Engineering
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In this study, we investigated the degradation process of metakaolin-based geopolymers exposed to high temperatures up to 1,000°C. The changes in mechanical properties, microstructure, and phase assemblage of the samples were studied, and the results demonstrated that at high temperatures the activator type [i.e., Na2SiO3/NaOH (Na/Na) and Na2SiO3/KOH (Na/K) solution] affected the degradation mechanisms of geopolymer mortars. (Na,K)-based geopolymer specimens demonstrated better thermal resistance at temperatures above 200°C. This was evident from the higher compressive strength, lower porosity, and less cracking tendency of this mixture. Compared to (Na,K)-based geopolymers, more mass loss may result in considerable drying shrinkage of (Na,Na)-based counterparts, which would further lead to the occurrence and development of cracks at ∼200°C. Above 200°C, the degradation of the mechanical properties of geopolymers could be attributed to crack development and degradation of material properties. Furthermore, compared to their (Na-Na)-based counterparts, (Na-K)-based geopolymers achieved improved chemical stability and did not form new crystalline phases above 1,000°C. Moreover, higher temperature exposure (1,000°C) led to significant sintering of geopolymers, forming a dense and homogeneous matrix and, as a result, improved mechanical properties of specimens. Overall, it showed that when specimens were exposed to different high temperatures, the mutual promoted effects between Na+ and K+ in geopolymers played a significant role in crack development, sintering, and new crystallization formation in the specimens.

ACS Style

Yajun Zhang; Dongming Yan; Nv Han; Yu Ao; Shikun Chen; Hailong Ye; Hamed Fazli; Tian-Nan Ye. Effects of Activator Types on Degradation Mechanisms of Metakaolin Geopolymer Mortars Exposed to High Temperature. Journal of Materials in Civil Engineering 2020, 32, 04020369 .

AMA Style

Yajun Zhang, Dongming Yan, Nv Han, Yu Ao, Shikun Chen, Hailong Ye, Hamed Fazli, Tian-Nan Ye. Effects of Activator Types on Degradation Mechanisms of Metakaolin Geopolymer Mortars Exposed to High Temperature. Journal of Materials in Civil Engineering. 2020; 32 (12):04020369.

Chicago/Turabian Style

Yajun Zhang; Dongming Yan; Nv Han; Yu Ao; Shikun Chen; Hailong Ye; Hamed Fazli; Tian-Nan Ye. 2020. "Effects of Activator Types on Degradation Mechanisms of Metakaolin Geopolymer Mortars Exposed to High Temperature." Journal of Materials in Civil Engineering 32, no. 12: 04020369.

Journal article
Published: 20 October 2020 in Cement and Concrete Research
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In this work, the influence of sodium nitrite (NaNO2) and sodium nitrate (NaNO3) corrosion inhibitors on the composition, structure, and chloride binding behaviors of layered double hydroxides (LDHs) formed in ternary ordinary Portland cement-metakaolin-dolomite (OPC-MK-DM) systems is studied. The results show that the nitrite and nitrate anions are preferably intercalated in the CaAl LDHs (AFm phases), but not in the MgAl LDHs (hydrotalcite-type phases) due to its limited formation in these ternary cementitious systems cured at ambient temperature. The autogenously formed nitrate- and nitrite-AFm phases are decomposed upon chloride exposure accompanied by Friedel's salts formation, potentially releasing corrosion inhibitive ions to the pore solution in a progressive manner. The NaNO2 and NaNO3 incorporation in ternary OPC-MK-DM binders marginally lowers chloride binding capacity but reduces its penetration resistance mainly due to pore coarsening. Nevertheless, a strong linear correlation can be established between the water-soluble and total chloride contents in ternary OPC-MK-DM systems, regardless of OPC replacement level and corrosion inhibitor incorporation.

ACS Style

Hailong Ye. Autogenous formation and smart behaviors of nitrite- and nitrate-intercalated layered double hydroxides (LDHs) in Portland cement-metakaolin-dolomite blends. Cement and Concrete Research 2020, 139, 106267 .

AMA Style

Hailong Ye. Autogenous formation and smart behaviors of nitrite- and nitrate-intercalated layered double hydroxides (LDHs) in Portland cement-metakaolin-dolomite blends. Cement and Concrete Research. 2020; 139 ():106267.

Chicago/Turabian Style

Hailong Ye. 2020. "Autogenous formation and smart behaviors of nitrite- and nitrate-intercalated layered double hydroxides (LDHs) in Portland cement-metakaolin-dolomite blends." Cement and Concrete Research 139, no. : 106267.

Journal article
Published: 16 October 2020 in Engineering Structures
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In this work, the bond degradation of non-uniformly corroded steel rebars embedded in concrete was studied. A total of 105 concrete specimens with accelerated corrosion of steel rebar were evaluated using the pull-out test. The influences of corrosion mode, corrosion level, orientation of the longitudinal rib, and the position of steel rebar on the bond degradation were analyzed. The cracking patterns of corrosion-induced cracks, bond failure modes, and bond stress-slip relations were discussed. The results showed that the orientation of longitudinal rib and the thickness of concrete cover play a vital role in determining the cracking patterns of corrosion-induced cracks. In comparison to the uniformly corroded specimens, the bond performance of specimens with non-uniform corrosion of steel rebar degraded more significantly, and this phenomenon became even more pronounced as the corrosion level increased. Moreover, the beneficial improvements caused by the expansive rust on the bond performance were greatly dependent on the degrees of concrete constraint and corrosion level.

ACS Style

Chuanqing Fu; Deming Fang; Hailong Ye; Le Huang; Jiandong Wang. Bond degradation of non-uniformly corroded steel rebars in concrete. Engineering Structures 2020, 226, 111392 .

AMA Style

Chuanqing Fu, Deming Fang, Hailong Ye, Le Huang, Jiandong Wang. Bond degradation of non-uniformly corroded steel rebars in concrete. Engineering Structures. 2020; 226 ():111392.

Chicago/Turabian Style

Chuanqing Fu; Deming Fang; Hailong Ye; Le Huang; Jiandong Wang. 2020. "Bond degradation of non-uniformly corroded steel rebars in concrete." Engineering Structures 226, no. : 111392.

Journal article
Published: 01 October 2020 in Journal of Materials in Civil Engineering
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The alkali-activation of high-volume fly ash (HVFA) produces a low-carbon sustainable cementitious binder with remarkable strength and chemical durability at room temperature. In this work, the influence of activator type (i.e., deionized water, NaOH, Na2SO4, Na2CO3 solutions), silica fume incorporation, and curing duration on the phase assemblage and strength and shrinkage developments of HVFA is studied. The results show that Na2SO4-activated HVFA shows the highest strength achievement, followed by Na2CO3, NaOH, and water. Alkali incorporation in HVFA considerably increases the shrinkage magnitude and is mainly attributed to the detrimental effect of alkalis on the viscoelasticity and stiffness of cementitious solids. The HVFA activated by the NaOH solution shows the largest shrinkage, followed by Na2CO3 and Na2SO4 solutions, despite comparable moisture loss. The curing duration does not significantly affect the shrinkage development of alkali-activated HVFA without silica fume. However, with silica fume incorporation, extending curing duration considerably reduces the shrinkage of alkali-activated HVFA. The phase and molecular analysis suggest that silica fume noticeably retards the reaction of HVFA systems but tends to increase the level of silica polymerization in gel products, regardless of activator type.

ACS Style

Hailong Ye; Le Huang. Shrinkage Characteristics of Alkali-Activated High-Volume Fly-Ash Pastes Incorporating Silica Fume. Journal of Materials in Civil Engineering 2020, 32, 04020307 .

AMA Style

Hailong Ye, Le Huang. Shrinkage Characteristics of Alkali-Activated High-Volume Fly-Ash Pastes Incorporating Silica Fume. Journal of Materials in Civil Engineering. 2020; 32 (10):04020307.

Chicago/Turabian Style

Hailong Ye; Le Huang. 2020. "Shrinkage Characteristics of Alkali-Activated High-Volume Fly-Ash Pastes Incorporating Silica Fume." Journal of Materials in Civil Engineering 32, no. 10: 04020307.

Journal article
Published: 18 September 2020 in Construction and Building Materials
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To better study the non-uniform corrosion cracking process of reinforced mortar specimens, the numerical simulation has been carried out from the perspective of meso-mechanics. By applying X-ray CT technology to extract the distribution of pores, a reinforced mortar model was established, containing large pores and mortar matrix. An elastoplastic damage constitutive model of mortar was proposed based on parallel spring theory, by which the differences between tensile and compressive damage are considered. Combined with Digital Volume Correlation (DVC) technology, the non-uniform corrosion expansion displacement field of the reinforcement surface was obtained as load, and was applied in the numerical simulation. Using the finite element analysis software ABAQUS, the whole non-uniform corrosion cracking process of reinforced mortar was simulated. The damage development process of this numerical model was then verified by the DVC calculation results at specific times. In addition, the differences between the damage development of reinforced mortar model under non-uniform and uniform corrosion displacement loads are discussed.

ACS Style

Haoyu Jiang; Haodong Ji; Nanguo Jin; Ye Tian; Xianyu Jin; Hailong Ye; Dongming Yan; Zushi Tian. Simulation and experimental verification of the non-uniform corrosion cracking process of reinforced mortar specimen. Construction and Building Materials 2020, 265, 120522 .

AMA Style

Haoyu Jiang, Haodong Ji, Nanguo Jin, Ye Tian, Xianyu Jin, Hailong Ye, Dongming Yan, Zushi Tian. Simulation and experimental verification of the non-uniform corrosion cracking process of reinforced mortar specimen. Construction and Building Materials. 2020; 265 ():120522.

Chicago/Turabian Style

Haoyu Jiang; Haodong Ji; Nanguo Jin; Ye Tian; Xianyu Jin; Hailong Ye; Dongming Yan; Zushi Tian. 2020. "Simulation and experimental verification of the non-uniform corrosion cracking process of reinforced mortar specimen." Construction and Building Materials 265, no. : 120522.

Journal article
Published: 11 August 2020 in Cement and Concrete Composites
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In this work, the chloride binding capacity and chloride penetration resistance of alkali-activated fly ash and metakaolin geopolymers synthesized with various alkali cation types (i.e., sodium or potassium) and aluminosilicate composition (i.e., combination of metakaolin and low-calcium pulverized fly ash) are studied. The chloride binding isotherms are measured using a modified equilibrium method and the effect of chloride exposure on the mineralogical alteration of geopolymers is studied by means of X-ray diffraction. The results show that the type of alkali cation considerably affects the chloride binding behaviors of metakaolin-fly ash geopolymers, regardless of aluminosilicate composition. In comparison to the potassium-based activator, sodium activator results in higher strength development, stronger chloride binding capacity, and better resistance to chloride penetration. The metakaolin-fly ash geopolymers immobilize chloride ions through both chemisorptions via the formation of chloride-bearing zeolites (e.g., Cl-chabazite) as well as physical adsorption. The dominant role of physical adsorption in binding mechanism suggests that a high proportion of hydroxyl group in the structure of sodium (or potassium)-aluminosilicate-hydrate (i.e., (N, K)-A-S-H) is exchangeable with chloride ions.

ACS Style

Chuanqing Fu; Hailong Ye; Kaiqi Zhu; Deming Fang; Jianbo Zhou. Alkali cation effects on chloride binding of alkali-activated fly ash and metakaolin geopolymers. Cement and Concrete Composites 2020, 114, 103721 .

AMA Style

Chuanqing Fu, Hailong Ye, Kaiqi Zhu, Deming Fang, Jianbo Zhou. Alkali cation effects on chloride binding of alkali-activated fly ash and metakaolin geopolymers. Cement and Concrete Composites. 2020; 114 ():103721.

Chicago/Turabian Style

Chuanqing Fu; Hailong Ye; Kaiqi Zhu; Deming Fang; Jianbo Zhou. 2020. "Alkali cation effects on chloride binding of alkali-activated fly ash and metakaolin geopolymers." Cement and Concrete Composites 114, no. : 103721.

Journal article
Published: 01 August 2020 in Journal of Materials in Civil Engineering
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ACS Style

Rui He; Chuanqing Fu; Hongyan Ma; Hailong Ye; Xianyu Jin. Prediction of Effective Chloride Diffusivity of Cement Paste and Mortar from Microstructural Features. Journal of Materials in Civil Engineering 2020, 32, 04020211 .

AMA Style

Rui He, Chuanqing Fu, Hongyan Ma, Hailong Ye, Xianyu Jin. Prediction of Effective Chloride Diffusivity of Cement Paste and Mortar from Microstructural Features. Journal of Materials in Civil Engineering. 2020; 32 (8):04020211.

Chicago/Turabian Style

Rui He; Chuanqing Fu; Hongyan Ma; Hailong Ye; Xianyu Jin. 2020. "Prediction of Effective Chloride Diffusivity of Cement Paste and Mortar from Microstructural Features." Journal of Materials in Civil Engineering 32, no. 8: 04020211.

Journal article
Published: 13 June 2020 in Construction and Building Materials
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The spatial distribution of coarse aggregates directly affects the three-dimensional transport of chloride ions and the accumulation of chloride ions on the surface of steel bar in reinforced concrete. The meso-structure of a concrete specimen was recognized through X-ray CT technology. In considering the diffusion of chloride ions both in mortar matrix and ITZs, a three-dimensional transmission model was established to numerically simulate the diffusion of chloride ions in concrete, which was furtherly verified by electronic microprobe technology. To avoid the correlation of data, 100 sets of independent three-dimensional numerical samples were generated with real coarse aggregates extracted from concrete specimen. The influence of spatial distribution of coarse aggregates on diffusion of chloride ions was statistically analyzed, and the differences between three-dimensional transmission and two-dimensional transmission of same sections were studied. The research shows that the special distribution of coarse aggregates can cause the non-uniform distribution of chloride ions both in spatial and time scale. The concentration distribution of chloride ions satisfies the Normal distribution through Kolmogorov-Smirnov test and Chi-square test. For two-dimensional and three-dimensional transmission, the greater the depth, the greater the differences in calculation results.

ACS Style

Haoyu Jiang; Ye Tian; Nanguo Jin; Xianyu Jin; Zushi Tian; Dongming Yan; Hailong Ye. Effect of aggregates spatial distribution on three-dimensional transport of chloride ions in reinforced concrete. Construction and Building Materials 2020, 259, 119694 .

AMA Style

Haoyu Jiang, Ye Tian, Nanguo Jin, Xianyu Jin, Zushi Tian, Dongming Yan, Hailong Ye. Effect of aggregates spatial distribution on three-dimensional transport of chloride ions in reinforced concrete. Construction and Building Materials. 2020; 259 ():119694.

Chicago/Turabian Style

Haoyu Jiang; Ye Tian; Nanguo Jin; Xianyu Jin; Zushi Tian; Dongming Yan; Hailong Ye. 2020. "Effect of aggregates spatial distribution on three-dimensional transport of chloride ions in reinforced concrete." Construction and Building Materials 259, no. : 119694.

Journal article
Published: 28 April 2020 in Construction and Building Materials
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An accurate prediction of time-dependent autogenous shrinkage behaviors of concrete, especially for high performance concrete (HPC) at an early age, is of great significance to assess and control the cracking risks of restrained structural elements. In this study, based on the capillary tension theory, a mechanistic model for evaluating the time-dependent autogenous shrinkage behaviors of high performance concrete is proposed. A total of 416 data points including the concrete composition, curing condition, age of concrete, water-to-cement (binder) ratio, internal relative humidity, elastic modulus, and measured autogenous shrinkage are selectively collected for the model establishment. The effects of silica fume on the development of autogenous shrinkage are also considered. Upon the sound physical basis, the model requires only a few parameter inputs related to the mixture proportion and physicochemical properties of constituents. The reasonable agreements between the analytical predictions and independent experimental results, as well as common used formulas from different codes (i.e., ACI 209, Eurocode 2, and Model Code 2010), demonstrate that the time-dependent evolution of autogenous shrinkage of HPC can be reasonably predicted by the model proposed in this study.

ACS Style

Le Huang; Zhijian Chen; Hailong Ye. A mechanistic model for the time-dependent autogenous shrinkage of high performance concrete. Construction and Building Materials 2020, 255, 119335 .

AMA Style

Le Huang, Zhijian Chen, Hailong Ye. A mechanistic model for the time-dependent autogenous shrinkage of high performance concrete. Construction and Building Materials. 2020; 255 ():119335.

Chicago/Turabian Style

Le Huang; Zhijian Chen; Hailong Ye. 2020. "A mechanistic model for the time-dependent autogenous shrinkage of high performance concrete." Construction and Building Materials 255, no. : 119335.

Journal article
Published: 23 April 2020 in Sensors
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In this work, the failure process of non-corroded and corroded reinforced concrete (RC) columns under eccentric compressive loading is studied using the acoustic emission (AE) technique. The results show that reinforcement corrosion considerably affects the mechanical failure process of RC columns. The corrosion of reinforcement in RC columns leads to highly active AE signals at the initial stage of loading, in comparison to the non-corroded counterparts. Also, a continuous AE hit pattern with a higher number of cumulative hits is observed for corroded RC columns. The spatial distribution and evolution of AE events indicate that the reinforcement corrosion noticeably accelerates the initiation and propagation of cracking in the RC columns during compressive loading. The AE characteristics of corroded RC columns are in agreement with the macroscopic failure behaviors observed during the damage and failure process. A damage evolution model of corroded RC columns based on the AE parameters is proposed.

ACS Style

Qiang Li; Xianyu Jin; Dan Wu; Hailong Ye. Acoustic Emission Analysis of Corroded Reinforced Concrete Columns under Compressive Loading. Sensors 2020, 20, 2412 .

AMA Style

Qiang Li, Xianyu Jin, Dan Wu, Hailong Ye. Acoustic Emission Analysis of Corroded Reinforced Concrete Columns under Compressive Loading. Sensors. 2020; 20 (8):2412.

Chicago/Turabian Style

Qiang Li; Xianyu Jin; Dan Wu; Hailong Ye. 2020. "Acoustic Emission Analysis of Corroded Reinforced Concrete Columns under Compressive Loading." Sensors 20, no. 8: 2412.

Research paper
Published: 19 April 2020 in International Journal of Civil Engineering
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ACS Style

Qiang Li; Le Huang; Hailong Ye; Chuanqing Fu; Xianyu Jin. Mechanical Degradation of Reinforced Concrete Columns Corroded Under Sustained Loads. International Journal of Civil Engineering 2020, 18, 883 -901.

AMA Style

Qiang Li, Le Huang, Hailong Ye, Chuanqing Fu, Xianyu Jin. Mechanical Degradation of Reinforced Concrete Columns Corroded Under Sustained Loads. International Journal of Civil Engineering. 2020; 18 (8):883-901.

Chicago/Turabian Style

Qiang Li; Le Huang; Hailong Ye; Chuanqing Fu; Xianyu Jin. 2020. "Mechanical Degradation of Reinforced Concrete Columns Corroded Under Sustained Loads." International Journal of Civil Engineering 18, no. 8: 883-901.