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Rice husk ash (RHA) has been considered as a suitable cement mineral additive. A key issue in the study of RHA blended cement is to evaluate the contribution of RHA to hydration kinetics. Although numerous methods have been given to assess the hydration degree of blended cement, there are still some controversial aspects, such as the effect of temperature is not well considered. Therefore, this study aims at developing a method for evaluating the hydration degree of blended cement which can consider the influence of temperature. The key of this method is to adopt a hydration kinetic model of nonevaporable water (NEW) to determine the ultimate NEW content of blended cement when it is completely hydrated. In the hydration kinetic model, the Arrhenius equation is introduced to reflect the relationship between hydration rate and temperature, and the inversion phenomenon between ultimate NEW and temperature is considered simultaneously. Furthermore, the hydration process of portland cement pastes containing RHA (two types of RHA: RHA-1 from the factory and RHA-2 by controlled combustion) is analyzed by this assessment method. It is found that the effect of temperature on RHA cement is similar to that of ordinary Portland cement (OPC), which has an inversion phenomenon between hydration degree and temperature. Under the same temperature, the hydration degree of RHA cements is lower than that of OPC, while the difference in hydration degree gradually decreases with the progress of hydration. Moreover, according to the fitting results of the model when m = 3, the addition of RHA could reduce the apparent activation energy (Ea) of blended cement, the Ea values of OPC, RHA-1 cement and RHA-2 cement are 37.64 kJ/mol, 35.39 kJ/mol and 34.18 kJ/mol, respectively.
Xue Luo; Xunli Jiang; Qi Chen; Zhiyi Huang. An assessment method of hydration degree of Rice husk ash blended cement considering temperature effect. Construction and Building Materials 2021, 304, 124534 .
AMA StyleXue Luo, Xunli Jiang, Qi Chen, Zhiyi Huang. An assessment method of hydration degree of Rice husk ash blended cement considering temperature effect. Construction and Building Materials. 2021; 304 ():124534.
Chicago/Turabian StyleXue Luo; Xunli Jiang; Qi Chen; Zhiyi Huang. 2021. "An assessment method of hydration degree of Rice husk ash blended cement considering temperature effect." Construction and Building Materials 304, no. : 124534.
Soft soils are usually treated to mitigate their engineering problems, such as excessive deformation, and stabilization is one of most popular treatments. Although there are many creep models to characterize the deformation behaviors of soil, there still exist demands for a balance between model accuracy and practical application. Therefore, this paper aims at developing a Mechanistic-Empirical creep model (MEC) for unsaturated soft and stabilized soils. The model considers the stress dependence and incorporates moisture sensitivity using matric suction and shear strength parameters. This formulation is intended to predict the soil creep deformation under arbitrary water content and arbitrary stress conditions. The results show that the MEC model is in good agreement with the experimental data with very high R-squared values. In addition, the model is compared with the other classical creep models for unsaturated soils. While the classical creep models require a different set of parameters when the water content is changed, the MEC model only needs one set of parameters for different stress levels and moisture conditions, which provides significant facilitation for implementation. Finally, a finite element simulation analysis of subgrade soil foundation is performed for different loading levels and moisture conditions. The MEC model is utilized to predict the creep behavior of subgrade soils. Under the same load and moisture level, the deformation of soft soil is largest, followed by lime soil and RHA–lime-stabilized soil, respectively.
Xunli Jiang; Zhiyi Huang; Xue Luo. An Improved Mechanistic-Empirical Creep Model for Unsaturated Soft and Stabilized Soils. Materials 2021, 14, 4146 .
AMA StyleXunli Jiang, Zhiyi Huang, Xue Luo. An Improved Mechanistic-Empirical Creep Model for Unsaturated Soft and Stabilized Soils. Materials. 2021; 14 (15):4146.
Chicago/Turabian StyleXunli Jiang; Zhiyi Huang; Xue Luo. 2021. "An Improved Mechanistic-Empirical Creep Model for Unsaturated Soft and Stabilized Soils." Materials 14, no. 15: 4146.
Cross-tensioned concrete pavement can reduce transverse joints and cracks and improve the durability of the pavement, and the decrease in slab thickness can be achieved without damaging the performance of the pavement. However, the corrosion of the steel can cause serious damage to the pavement structure, resulting in higher maintenance costs and shorter service life. Basalt fiber-reinforced polymer (BFRP) has been proven to be an effective alternative in both jointed plain concrete pavement (JPCP) and continuously reinforced concrete pavement (CRCP) due to its lightweight and corrosion-resistant properties. In this paper, a systematic theoretical method for determining the prestress loss of BFRP tendons in cross-tensioned concrete pavement was proposed, with the impact of the slab width and distribution angle of the prestressed tendon on the prestress loss being studied and compared to the results of traditional steel strands. Results showed that the proportion of the prestress loss due to anchorage deformation and prestress retraction in the prestressing stage rose with the increase in distribution angle and the decrease in slab width, while the prestress loss during the in-service stage was a constant value for both BFRP tendons and steel strands. The prestress loss of BFRP tendons was far lower than that of steel strands in both prestressing stage and in-service stage for a given slab width (3 m, 4.5 m, 9.0 m, 12.75 m) and distribution angle (20°, 25°, 30°, 35°, 40°, 45°), and the difference ranged from 6.4% to 16%, signifying the feasibility of BFRP tendons in cross-tensioned concrete pavement. Overall, the smaller the slab width, the greater the difference of the prestress loss between BFRP tendons and steel strands.
Yating Zhang; Zhiyi Huang. Theoretical Study on Prestress Loss in Cross-Tensioned Concrete Pavement with BFRP Tendons. Applied Sciences 2020, 10, 7737 .
AMA StyleYating Zhang, Zhiyi Huang. Theoretical Study on Prestress Loss in Cross-Tensioned Concrete Pavement with BFRP Tendons. Applied Sciences. 2020; 10 (21):7737.
Chicago/Turabian StyleYating Zhang; Zhiyi Huang. 2020. "Theoretical Study on Prestress Loss in Cross-Tensioned Concrete Pavement with BFRP Tendons." Applied Sciences 10, no. 21: 7737.
Continuously reinforced concrete pavement (CRCP) is a pavement structure with a high performance and long service life. However, the corrosion of the longitudinal steel can result in a poor bond relationship between the steel and the concrete, affecting the load transfer efficiency between the adjacent panels and being responsible for the development of CRCP distresses. Basalt fiber-reinforced polymer (BFRP) is corrosion-resistant and has the potential to be used in CRCP. In this paper, the layout of a CRCP test section with BFRP bars constructed on G330 National Road in Zhejiang Province, China, is presented. An analytical model is proposed to predict the crack behavior of CRCP with BFRP reinforcement, with the predicted results are compared to field-measured ones. A sensitivity analysis of the BFRP design parameters on the crack spacing and crack width is conducted as well. The results show that the mean values for field-measured crack spacing and crack width are 4.85 m and 1.30 mm, respectively, which are higher than the results for traditional CRCP with steel due to the lower elastic modulus of BFRP. The analytical predictions agree reasonably well with the crack survey results. The higher the elastic modulus of BFRP, the reinforcement content (with both BFRP spacing and diameter related), and the bond stiffness coefficient between the BFRP and concrete, the less the crack spacing and crack width will be. Given the same or similar reinforcement content, a lower diameter with a smaller spacing is recommended because of its contribution to a smaller crack spacing and width.
Yating Zhang; Zhiyi Huang. Transverse Crack Behavior in Continuously Reinforced Concrete Pavement with Basalt Fiber Reinforcement. Applied Sciences 2020, 10, 7458 .
AMA StyleYating Zhang, Zhiyi Huang. Transverse Crack Behavior in Continuously Reinforced Concrete Pavement with Basalt Fiber Reinforcement. Applied Sciences. 2020; 10 (21):7458.
Chicago/Turabian StyleYating Zhang; Zhiyi Huang. 2020. "Transverse Crack Behavior in Continuously Reinforced Concrete Pavement with Basalt Fiber Reinforcement." Applied Sciences 10, no. 21: 7458.
The recovery of asphalt mixtures during rest periods is a key factor that affects the performance and service life of asphalt pavements in addition to the loading period. However, much less attention has been paid to the unloading periods in terms of laboratory characterization and numerical modeling. Thus, this study is intended to develop a coupled mechanical and kinetic approach to accurately characterize and simulate the recovery phase of asphalt mixtures. For the unloading period, a kinetics-based recovery model is proposed, which consists of two periods (fast-rate period and constant-rate period) with the kinetic parameters like the recovery activation energy and pre-exponential factors. In addition, a generalized Maxwell model is proposed to characterize the change of the recovery modulus predicted by the kinetics-based recovery model, which would facilitate the implementation in the numerical simulation process. For the loading period, an improved constitutive model is developed for the damage process of asphalt mixtures based on the relation between the pseudo strain and damage density. The proposed models are then applied to laboratory tests and finite element modeling on different asphalt mixtures with two types of binders, three aging periods, two air void contents, and nondestructive and destructive loading conditions. The laboratory results show that the kinetic parameters like the recovery/healing activation energy are good indictors of recovery/healing capacity of asphalt mixtures. The numerical simulations demonstrate that the output responses match very well with the measured values under both the nondestructive and destructive loading conditions, which verify the accuracy of the proposed approaches.
Xue Luo; Fuquan Ma; Bjorn Birgisson; Zhiyi Huang. Coupled mechanical and kinetic modeling of recovery in asphalt mixtures. Construction and Building Materials 2020, 254, 118889 .
AMA StyleXue Luo, Fuquan Ma, Bjorn Birgisson, Zhiyi Huang. Coupled mechanical and kinetic modeling of recovery in asphalt mixtures. Construction and Building Materials. 2020; 254 ():118889.
Chicago/Turabian StyleXue Luo; Fuquan Ma; Bjorn Birgisson; Zhiyi Huang. 2020. "Coupled mechanical and kinetic modeling of recovery in asphalt mixtures." Construction and Building Materials 254, no. : 118889.
The use of nanomaterials to modify the asphalt mixture to enhance its performance has become an area of growing interest. Graphene oxide (GO) has recently been found to be the potential nanomaterial for improving the performance of asphalt binder due to its advantageous properties and dispersion ability in different matrixes. In this study, GO modified asphalt binder was employed in hot mix asphalt to assess its influence on the engineering characteristics of hot mix asphalt (HMA). A base asphalt binder with 60/70 penetration grade was first mixed with GO at different concentrations using a high shear mixing equipment and then employed to prepare the asphalt mixtures. A series of performance tests, e.g., resilient modulus, dynamic creep, freeze–thaw splitting, Marshall immersion and semi-circular bending (SCB) fracture were conducted to investigate the rutting and fatigue performance, moisture stability and fracture resistance of the GO-modified HMA mixtures. Results suggest that significant improvement in mechanics behavior of HMA may be achieved by incorporating GO compared to the conventional mixture.
Abbas Mukhtar Adnan; Xue Luo; Chaofeng Lü; Jinchang Wang; Zhiyi Huang. Improving mechanics behavior of hot mix asphalt using graphene-oxide. Construction and Building Materials 2020, 254, 119261 .
AMA StyleAbbas Mukhtar Adnan, Xue Luo, Chaofeng Lü, Jinchang Wang, Zhiyi Huang. Improving mechanics behavior of hot mix asphalt using graphene-oxide. Construction and Building Materials. 2020; 254 ():119261.
Chicago/Turabian StyleAbbas Mukhtar Adnan; Xue Luo; Chaofeng Lü; Jinchang Wang; Zhiyi Huang. 2020. "Improving mechanics behavior of hot mix asphalt using graphene-oxide." Construction and Building Materials 254, no. : 119261.
The disease of the operating tunnel lining has seriously threatened traffic safety and needs to be cured urgently. Engineered Cementitious Composite (ECC), due to its excellent deformation ability and high damage tolerance, has the potential to retrofit the linings, but the quite high cost of raw material, mainly involving PVA fiber, has limited the broader application of ECC in the civil infrastructure. This paper proposed a practical design method of integrating four parts: engineering requirements, economical cost, matrix design and environmental assessment. A novel type of cementitious composites with low water absorption, moderate flexibility and light-weigh, named functional cementitious composite (FCC), was exploited to handle the common diseases of tunnel lining economically and environmentally. The results indicated that the cost-effective fiber is available to prepare the FCC, which shows great performance of cost-saving and functional properties. Besides, the functional characteristics, including low water sorptivity, light density and moderate flexibility, were optimized by response surface methodology (RSM) and subsequently the optimized results were proven by the test results. Finally, the environmental assessment emphasized an excellent material greenness of FCC with reduction of 26.9% embodied energy consumption and 26.2% carbon equivalent emission compared to the ECC (M45).
Zhanfeng Qi; Wenhua Chen; Lei Zhang; Zhiyi Huang. An integrated design method for functional cementitious composites (FCC). Construction and Building Materials 2020, 249, 118698 .
AMA StyleZhanfeng Qi, Wenhua Chen, Lei Zhang, Zhiyi Huang. An integrated design method for functional cementitious composites (FCC). Construction and Building Materials. 2020; 249 ():118698.
Chicago/Turabian StyleZhanfeng Qi; Wenhua Chen; Lei Zhang; Zhiyi Huang. 2020. "An integrated design method for functional cementitious composites (FCC)." Construction and Building Materials 249, no. : 118698.
The recovery property of asphalt binders plays an important role in the performance and service life of asphalt pavements. Since the internal stress is the driving force for the recovery of asphalt binders, the accurate measurement of the internal stress is full of significance. Based on this rationale, this paper aims to measure the internal stress of asphalt binders using a creep and step-loading recovery (CSR) test and characterizing the recovery behaviors by the internal stress. One base asphalt binder and one styrene–butadiene–styrene (SBS)-modified binder are selected in this study. The key elements of the CSR test are carefully designed and its accuracy is verified in three aspects, including the loading conditions, the effect of disturbance by step-loads, and accuracy of measured internal stress. Then, a kinetics-based recovery model is proposed to evaluate and predict the recovery properties of asphalt binders from its causal relationship. The constant-rate recovery activation energy indicates a major difference with nondestructive and destructive loading conditions, while the fast-rate recovery activation energy keeps almost constant regardless of the loading conditions. After that, the healing activation energy is calculated by using the kinetics-based recovery model and the results indicate that SBS modified asphalt binder shows better healing abilities than a base binder.
Fuquan Ma; Xue Luo; Zhiyi Huang; Jinchang Wang. Characterization of Recovery in Asphalt Binders. Materials 2020, 13, 920 .
AMA StyleFuquan Ma, Xue Luo, Zhiyi Huang, Jinchang Wang. Characterization of Recovery in Asphalt Binders. Materials. 2020; 13 (4):920.
Chicago/Turabian StyleFuquan Ma; Xue Luo; Zhiyi Huang; Jinchang Wang. 2020. "Characterization of Recovery in Asphalt Binders." Materials 13, no. 4: 920.
The effects of cenospheres, an industrial waste residue, on the compressive strength, flexural strength, toughness, ductility, chemical component, microstructures, and micromechanics of lightweight toughness cement-based composites (LTCCs) by comprehensive experimental tests are explored in this paper. The results indicate that an increase in the amount of cenospheres leads to a decrease in the compressive and flexural strength of LTCCs. However, the specific strength of LTCCs increases with increasing cenosphere content. LTCCs containing 20% cenospheres and 1% fiber volume have the best toughness and ductility. Significant strain hardening occurs during the four-point bending and uniaxial tensile process. Furthermore, the incorporation of cenospheres promotes the hydration reaction of LTCCs due to its high pozzolanic activity. The LTCC cement paste has a low bonding strength to the fiber, which helps the fiber to be pulled out to produce greater bending deformation and tensile strain. The elastic modulus and hardness of the LTCC cement paste decrease linearly with increasing cenosphere content, which also causes the LTCC microstructure to become loose and more ettringite to generate. The weak interfacial transition zone between the cenospheres and the cement matrix is the important reason for the decreasing compressive strength of the LTCC. In conclusion, LTCC incorporating cenospheres is suitable for long-span steel deck pavements due to its light weight and excellent toughness. The successful application of cenospheres in engineering construction can save natural resources and contribute to sustainable development.
Wenhua Chen; Zhiyi Huang. Experimental Study of the Mechanical Properties and Microstructures of Lightweight Toughness Cement-Based Composites. Materials 2019, 12, 3891 .
AMA StyleWenhua Chen, Zhiyi Huang. Experimental Study of the Mechanical Properties and Microstructures of Lightweight Toughness Cement-Based Composites. Materials. 2019; 12 (23):3891.
Chicago/Turabian StyleWenhua Chen; Zhiyi Huang. 2019. "Experimental Study of the Mechanical Properties and Microstructures of Lightweight Toughness Cement-Based Composites." Materials 12, no. 23: 3891.
With increased awareness of environmental protection, the output of traditional curing agents such as cement and lime is less and less, so it is urgent to develop new curing agents with high efficiency and environmental benefits. Thus, this study aims at investigating the application of rice husk ash (RHA) from agricultural waste to the soft soil stabilization. A series of tests are conducted to analyze the strength development process and soil–water characteristics of rice husk ash–lime (RHA–lime) stabilized soils. The results of the strength tests showed that by increasing the content of RHA, the unconfined compressive strength (UCS) and splitting strength of stabilized soils increased first and then decreased. The effective shear strength indexes of the three soil types (soft soil, lime-stabilized soil, and RHA–lime soil) are measured and compared. It is found that RHA can effectively improve the shear resistance and water resistance of stabilized soil. The results of methylene blue test demonstrated that RHA can also promote the reduction of the specific surface area and swelling potential energy of lime-stabilized soil. In addition, the influence of RHA on mineral composition and morphology change in stabilized soils is studied at the microscopic level. The X-ray diffraction tests and scanning electron microscope (SEM) tests showed that strength development and change of soil–water properties of RHA–lime stabilized soil are attributed to enhanced cohesion by cementation and pores filling with agglomerated mineral.
Xunli Jiang; Zhiyi Huang; Fuquan Ma; Xue Luo; Ma; Luo. Analysis of Strength Development and Soil–Water Characteristics of Rice Husk Ash–Lime Stabilized Soft Soil. Materials 2019, 12, 3873 .
AMA StyleXunli Jiang, Zhiyi Huang, Fuquan Ma, Xue Luo, Ma, Luo. Analysis of Strength Development and Soil–Water Characteristics of Rice Husk Ash–Lime Stabilized Soft Soil. Materials. 2019; 12 (23):3873.
Chicago/Turabian StyleXunli Jiang; Zhiyi Huang; Fuquan Ma; Xue Luo; Ma; Luo. 2019. "Analysis of Strength Development and Soil–Water Characteristics of Rice Husk Ash–Lime Stabilized Soft Soil." Materials 12, no. 23: 3873.
In the coastal areas of southeastern China, high temperatures and humidity in the summer and microfreezing in the winter, as well as a high concentration of salt spray in the environment, seriously deteriorate the durability of asphalt mixtures. Therefore, the microcharacteristics of asphalt mastics (asphalt mixed with mineral filler) under the effect of chlorine salt and "dry-wet and freeze-thaw" (DW-FT) cycles were investigated by Fourier-transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC), and atomic force microscopy (AFM) techniques. Two factors, including asphalt mastic types (base and styrene-butadiene-styrene (SBS)-modified mastics) and numbers of DW-FT cycles, were considered based on the natural environment. Regression functions were established to explore the relationship between the FTIR, GPC, and AFM indexes. The results indicate that there were no chemical reactions between the asphalt and filler because the infrared spectrum of the base and SBS-modified mastics were similar. With the increase of the salt "DW-FT" cycle numbers, the sulfoxide index and large molecular size ratios ( L M S % ) increased, and the surface roughness ( R q and R a ) of the morphology decreased, as illustrated by a flatting mastics surface phenomenon in the AFM test. Regression analysis confirmed that there was a high correlation between the FTIR, GPC, and AFM indexes, and formation of the bee structures was closely related to the long chain index. The SBS-modified mastics had a better antiaging performance with a lower increase in the sulfoxide index after the salt "DW-FT" cycles in the coastal environment.
Qinling Zhang; Zhiyi Huang. Investigation of the Microcharacteristics of Asphalt Mastics under Dry-Wet and Freeze-Thaw Cycles in a Coastal Salt Environment. Materials 2019, 12, 2627 .
AMA StyleQinling Zhang, Zhiyi Huang. Investigation of the Microcharacteristics of Asphalt Mastics under Dry-Wet and Freeze-Thaw Cycles in a Coastal Salt Environment. Materials. 2019; 12 (16):2627.
Chicago/Turabian StyleQinling Zhang; Zhiyi Huang. 2019. "Investigation of the Microcharacteristics of Asphalt Mastics under Dry-Wet and Freeze-Thaw Cycles in a Coastal Salt Environment." Materials 12, no. 16: 2627.
The flame retardancy of asphalt binders with layered double hydroxides (LDHs) was investigated using limiting oxygen index (LOI) and cone calorimeter tests. The flame-retardant mechanism of the LDHs was also studied with thermogravimetry and differential scanning calorimetry (TG⁻DSC), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The cone calorimeter testing results indicated that 2 wt.% of the LDHs can decease the peak heat and smoke release rate of asphalt binders. Because a low dose of LDHs can be well dispersed in asphalt binder and favor the formation of polyaromatic structures during combustion, the thermal oxidation resistance and compactness of the char layer can be improved. The LOI of asphalt binder can be increased and the heat and smoke release during combustion can be decreased with 25 wt.% LDHs. The decomposition of LDHs can absorb the heat release of the initial two stages of asphalt combustion and reduce the burning rate of asphalt. Due to the loss of loosely bound water in the LDHs during the blending process and the decrease of dispersibility at a high LDH dose, the improvement of thermal stability is limited.
Kai Zhu; Yunhe Wang; Daquan Tang; Qiang Wang; Haihang Li; Yadong Huang; Zhiyi Huang; Ke Wu. Flame-Retardant Mechanism of Layered Double Hydroxides in Asphalt Binder. Materials 2019, 12, 801 .
AMA StyleKai Zhu, Yunhe Wang, Daquan Tang, Qiang Wang, Haihang Li, Yadong Huang, Zhiyi Huang, Ke Wu. Flame-Retardant Mechanism of Layered Double Hydroxides in Asphalt Binder. Materials. 2019; 12 (5):801.
Chicago/Turabian StyleKai Zhu; Yunhe Wang; Daquan Tang; Qiang Wang; Haihang Li; Yadong Huang; Zhiyi Huang; Ke Wu. 2019. "Flame-Retardant Mechanism of Layered Double Hydroxides in Asphalt Binder." Materials 12, no. 5: 801.
Strain hardening cementitious composites (SHCCs) are widely used in projects due to their excellent deformation resistance and large energy absorption capacity. However, determining tensile strain capacity is still a challenge for engineers. The current popular approach is to use inverse methods to predict the tensile behavior of SHCCs, such as the UM method (Qian and Li) and the JCI (Japan Concrete Institute) method. The key to these two approaches is to acquire the exact relationship between the bending and the uniaxial response. In this paper, a reasonable linear constitutive model of the SHCCs is modified. Initially, the moment-curvature diagrams are discussed by material parameters. The results reveal that the moment-curvature response is quite sensitive to the variations in the parameter of transition strain α, post-cracking tensile stiffness η, and strain softening stiffness μ, however, for the compressive parameters, the moment-curvature responses influence on flexural behavior is insignificant. Moreover, the load-deflection curve in the mid-span of SHCC, based on the consideration of shear effect, is simulated under a four-point bending test (FPBT). The results show a remarkable consistency with the experimental data when compared to the previous simulations. It is expected that this modified method can enhance an accurate program in order to obtain the tensile capacity.
Zhanfeng Qi; Zhiyi Huang; Hui Li; Wenhua Chen. Study of Flexural Response in Strain Hardening Cementitious Composites Based on Proposed Parametric Model. Materials 2018, 12, 113 .
AMA StyleZhanfeng Qi, Zhiyi Huang, Hui Li, Wenhua Chen. Study of Flexural Response in Strain Hardening Cementitious Composites Based on Proposed Parametric Model. Materials. 2018; 12 (1):113.
Chicago/Turabian StyleZhanfeng Qi; Zhiyi Huang; Hui Li; Wenhua Chen. 2018. "Study of Flexural Response in Strain Hardening Cementitious Composites Based on Proposed Parametric Model." Materials 12, no. 1: 113.
Initial water content significantly affects the efficiency of soil stabilization. In this study, the effects of initial water content on the compressibility, strength, microstructure, and composition of a lean clay soil stabilized by compound calcium-based stabilizer were investigated by static compaction test, unconfined compression test, optical microscope observations, environment scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. The results indicate that as the initial water content increases in the range studied, both the compaction energy and the maximum compaction force decrease linearly and there are less soil aggregates or agglomerations, and a smaller proportion of large pores in the compacted mixture structure. In addition, for specimens cured with or without external water supply and under different compaction degrees, the variation law of the unconfined compressive strength with initial water content is different and the highest strength value is obtained at various initial water contents. With the increase of initial water content, the percentage of the oxygen element tends to increase in the reaction products of the calcium-based stabilizer, whereas the primary mineral composition of the soil-stabilizer mixture did not change notably.
Chenglong Yin; Wei Zhang; Xunli Jiang; Zhiyi Huang. Effects of Initial Water Content on Microstructure and Mechanical Properties of Lean Clay Soil Stabilized by Compound Calcium-Based Stabilizer. Materials 2018, 11, 1933 .
AMA StyleChenglong Yin, Wei Zhang, Xunli Jiang, Zhiyi Huang. Effects of Initial Water Content on Microstructure and Mechanical Properties of Lean Clay Soil Stabilized by Compound Calcium-Based Stabilizer. Materials. 2018; 11 (10):1933.
Chicago/Turabian StyleChenglong Yin; Wei Zhang; Xunli Jiang; Zhiyi Huang. 2018. "Effects of Initial Water Content on Microstructure and Mechanical Properties of Lean Clay Soil Stabilized by Compound Calcium-Based Stabilizer." Materials 11, no. 10: 1933.
In longitudinal ventilation, circulating air is formed in portals for closely spaced twin tunnels, which causes mixing between the polluted air exhausted from one tunnel and the fresh air flow of another tunnel, thus leading to the rising costs of ventilation system construction and operation. In this study, for the closely spaced tunnel with staggered inlet and outlet, the computational fluid dynamics (CFD) numerical simulation method was adopted to reveal flow characteristics of the circulating air as well as variation rules of the circulating air mixing ratio φc with tunnel structure and operation parameters. Results show that both reducing inlet air velocity and increasing outlet air velocity and lateral distance can reduce the impact of the negative-pressure zone at the tunnel entrance on the jet flow structure at the tunnel exit, thus weakening the circulating air. When the inlet is placed behind or aligned with the outlet (staggered distance ∆l ≤ 0), φc will increase linearly along with the increase of staggered distance; when the inlet is placed before the outlet (∆l > 0), φc will first increase and then decrease with the increase of staggered distance. An expression to predict circulating air mixing ratio was created by sections. The predictions show a good correlation with the measurements and indicate that the front slope gradient of the tunnel portal is also one of the factors affecting the circulating air mixing ratio.
Xin Zhang; Tianhang Zhang; Kai Zhu; Zhiyi Huang; Ke Wu. Numerical Research on the Mixture Mechanism of Polluted and Fresh Air at the Staggered Tunnel Portals. Applied Sciences 2018, 8, 1365 .
AMA StyleXin Zhang, Tianhang Zhang, Kai Zhu, Zhiyi Huang, Ke Wu. Numerical Research on the Mixture Mechanism of Polluted and Fresh Air at the Staggered Tunnel Portals. Applied Sciences. 2018; 8 (8):1365.
Chicago/Turabian StyleXin Zhang; Tianhang Zhang; Kai Zhu; Zhiyi Huang; Ke Wu. 2018. "Numerical Research on the Mixture Mechanism of Polluted and Fresh Air at the Staggered Tunnel Portals." Applied Sciences 8, no. 8: 1365.
Herein, the mechanical properties and carbonation durability of engineered cementitious composites (ECC) were studied. For the cost-efficient utilization of ECC materials, different types of specimens were cast with polypropylene (PP) and hydrophilic polyvinyl alcohol (HPVA) fibers. The compressive strength, Poisson’s ratio, strength-deflection curves, cracking/post-cracking strength, impact index, and tensile strain-stress curves of two types of ECC materials, with differing fiber contents of 0 vol %, 1 vol %, 1.5 vol %, and 2 vol %, were investigated with the use of compressive tests, four-point bending tests, drop-weight tests, and uniaxial tensile tests. In addition, the matrix microstructure and failure morphology of the fiber in the ECC materials were studied by scanning electron microscopy (SEM) analysis. Furthermore, carbonation tests and characterization of steel corrosion after carbonization were employed to study durability resistance. The results indicated that for both PP fiber- and HPVA fiber-reinforced ECCs, the compressive strength first increases and then decreases as fiber content increases from 0 vol % to 2 vol %, reaching a maximum at 1 vol % fiber content. The bending strength, deformation capacity, and impact resistance show significant improvement with increasing fiber content. The ECC material reinforced with 2 vol % PP fiber shows superior carbonized durability with a maximum carbonation depth of only 0.8 mm.
Wei Zhang; Chenglong Yin; Fuquan Ma; Zhiyi Huang. Mechanical Properties and Carbonation Durability of Engineered Cementitious Composites Reinforced by Polypropylene and Hydrophilic Polyvinyl Alcohol Fibers. Materials 2018, 11, 1147 .
AMA StyleWei Zhang, Chenglong Yin, Fuquan Ma, Zhiyi Huang. Mechanical Properties and Carbonation Durability of Engineered Cementitious Composites Reinforced by Polypropylene and Hydrophilic Polyvinyl Alcohol Fibers. Materials. 2018; 11 (7):1147.
Chicago/Turabian StyleWei Zhang; Chenglong Yin; Fuquan Ma; Zhiyi Huang. 2018. "Mechanical Properties and Carbonation Durability of Engineered Cementitious Composites Reinforced by Polypropylene and Hydrophilic Polyvinyl Alcohol Fibers." Materials 11, no. 7: 1147.
Heat dissipation enhancement of LED luminaries is of great significance to the large-scale application of LED. Luminaries-level structure improvement by the method of boring through-hole is adopted to intensify heat dissipation. Furthermore, the natural convection heat transfer process of LED luminaries is simulated by computational fluid dynamics (CFD) model before and after the structural modification. As shown by computational results, boring through-hole is beneficial to develop bottom-to-top natural convection, eliminate local circumfluence, and finally form better flow pattern. Analysis based on field synergy principle shows that boring through-hole across LED luminaries improves the synergy between flow field and temperature field, and effectively decreases the thermal resistance of luminaries-level heat dissipation structure. Under the same computational conditions, by luminaries-level structure improvement the highest temperature of heat sink is decreased by about 8°C and the average heat transfer coefficient is increased by 45.8%.
Ke Wu; Le Wang; Yi-Bo Yu; Zhi-Yi Huang; Pei Liang. Luminaries-level structure improvement of LEDs for heat dissipation enhancement under natural convection. Sādhanā 2013, 38, 1357 -1368.
AMA StyleKe Wu, Le Wang, Yi-Bo Yu, Zhi-Yi Huang, Pei Liang. Luminaries-level structure improvement of LEDs for heat dissipation enhancement under natural convection. Sādhanā. 2013; 38 (6):1357-1368.
Chicago/Turabian StyleKe Wu; Le Wang; Yi-Bo Yu; Zhi-Yi Huang; Pei Liang. 2013. "Luminaries-level structure improvement of LEDs for heat dissipation enhancement under natural convection." Sādhanā 38, no. 6: 1357-1368.
A fast multipole formulation for 2D linear viscoelastic problems is presented in this paper by incorporating the elastic–viscoelastic correspondence principle. Systems of multipole expansion equations are formed and solved analytically in Laplace transform domain. Three commonly used viscoelastic models are introduced to characterize the time-dependent behavior of the materials. Since the transformed multipole formulations are identical to those for the 2D elastic problems, it is quite easy to implement the 2D viscoelastic fast multipole boundary element method. Besides, all the integrals are evaluated analytically, leading to highly accurate results and fast convergence of the numerical scheme. Several numerical examples, including planar viscoelastic composites with single inclusion or randomly distributed multi-inclusions, as well as the problem of a crack in a pressured viscoelastic plane, are presented. The results are verified by comparison with the developed analytical solutions to illustrate the accuracy and efficiency of the approach.
X.Y. Zhu; W.Q. Chen; Z.Y. Huang; Y.J. Liu. A fast multipole boundary element method for 2D viscoelastic problems. Engineering Analysis with Boundary Elements 2010, 35, 170 -178.
AMA StyleX.Y. Zhu, W.Q. Chen, Z.Y. Huang, Y.J. Liu. A fast multipole boundary element method for 2D viscoelastic problems. Engineering Analysis with Boundary Elements. 2010; 35 (2):170-178.
Chicago/Turabian StyleX.Y. Zhu; W.Q. Chen; Z.Y. Huang; Y.J. Liu. 2010. "A fast multipole boundary element method for 2D viscoelastic problems." Engineering Analysis with Boundary Elements 35, no. 2: 170-178.