13 results on '"Chu, Hongyan"'
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2. Mechanical Properties and Microstructure of High Performance Lightweight Concrete.
- Author
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CHU Hongyan, AN Yuanyuan, QIN Jianjian, and JIANG Jinyang
- Subjects
MATERIALS science ,HIGH strength concrete ,POROSITY ,MICROSTRUCTURE ,FLEXURAL strength ,ELASTIC modulus ,CERAMICS - Abstract
High performance lightweight concrete (HPLC) characterized by low density, high strength and good durability, has prosperous application prospects in civil engineering. In this experiment, the modified Andreasen and Andersen model was used to design the initial mixture of HPLC. Shale ceramic sand (SCS) with different content was used to replace lightweight internal curing sand to prepare HPLC. The effect of different content of SCS on workability, mechanical properties and durability of HPLC were systematically investigated. In addition, this work explored the effect of SCS on the micro-morphology and pore structure of HPLC. It is found that: 1) When the replacement rate of SCS is 100%, the apparent density of HPLC is 1 848. 3 kg/m³, and its compressive strength is 123. 22 MPa. 2) The addition of SCS can improve the mechanical properties of HPLC, and the compressive strength, flexural strength and elastic modulus of HPLC increase by 8. 88% ~ 47. 92%, 22. 50% ~ 56. 30% and 3. 49% ~ 14. 03%, respectively. 3) SCS can improve the durability of HPLC. When SCS replacement rate is 100%, the chloride migration coefficient of HPLC is reduced by 32. 52%, compared to the control group. 4) Due to the addition of SCS, the microstructure of HPLC is significantly improved, and the porosity of HPLC reduces by 14. 86% ~28. 24%. [ABSTRACT FROM AUTHOR]
- Published
- 2023
3. Effects of graphene oxide on mechanical properties and microstructure of ultra-high-performance lightweight concrete.
- Author
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Chu, Hongyan, Qin, Jianjian, Gao, Li, Jiang, Jinyang, Wang, Fengjuan, and Wang, Danqian
- Subjects
HIGH strength concrete ,LIGHTWEIGHT concrete ,GRAPHENE oxide ,MICROSTRUCTURE ,ELASTIC modulus ,FLEXURAL strength - Abstract
Ultra-high-performance concrete (UHPC) has attracted much attention in civil engineering. However, the high deadweight of UHPC limits its application. To reduce the density of UHPC, this study developed an ultra-high-performance lightweight concrete (UHPLC) by combining the use of shale ceramic sand and nano-materials, according to the modified Andreasen and Andersen (MAA) model. Taking advantage of nanotechnology, graphene oxide (GO) was utilized to improve the mechanical performance of UHPLC, and the effects of GO on the workability, mechanical properties, and microstructure of UHPLC were systematically investigated. It was found that: 1) UHPLC with an apparent density of 2022 ∼ 2114 kg/m³ was prepared according to the MAA model; 2) Owing to the addition of GO, the flexural strength, compressive strength, and elastic modulus of UHPLC increased by 6.3 ∼ 22.4%, 7.6 ∼ 16.7%, and 4.1 ∼ 13.0%, respectively; 3) Considering the effects of GO on the mechanical properties and microstructure of UHPLC, the optimal content of GO was 0.06%. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
4. Workability, hydration, microstructure, and mechanical properties of UHPC produced with aeolian sand
- Author
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Fengjuan Wang, Gu Yehan, Liguo Wang, Jinyang Jiang, Chu Hongyan, and Ju Siyi
- Subjects
Materials science ,Aeolian sand ,Ceramics and Composites ,Geotechnical engineering ,Microstructure ,Waste Management and Disposal - Abstract
Recently, the use of aeolian sand for producing ultra-high-performance concrete (UHPC) was introduced. Preliminary investigations suggested that it was feasible to use aeolian sand to produce UHPC....
- Published
- 2021
5. An Approach of Producing Ultra-High-Performance Concrete with High Elastic Modulus by Nano-Al 2 O 3 : A Preliminary Study.
- Author
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Chu, Hongyan, Wang, Qun, Gao, Li, Jiang, Jinyang, and Wang, Fengjuan
- Subjects
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HIGH strength concrete , *POROSITY , *FLEXURAL strength , *COMPRESSIVE strength , *ELASTIC modulus , *CIVIL engineers - Abstract
Ultra-high-performance concrete (UHPC) has promising applications in civil engineering. However, the elastic modulus of UHPC is relatively low compared with its compressive strength, which may result in insufficient stiffness in service. This work was carried out to explore the feasibility of producing UHPC with high elastic modulus by nano-Al2O3 (NA). Based on particle densely packing theory, the initial mixture of UHPC was designed via the modified Andreasen and Andersen model. An experimental investigation was conducted to systematically examine the effects of NA on different properties of UHPC, including its fluidity, mechanical properties, durability, and microstructure. It was found that: (1) Compared with UHPC without NA, the flexural strength, compressive strength, and elastic modulus of UHPC were improved by 7.38–16.87%, 4.08–20.58%, and 2.89–14.08%, respectively, because of the incorporation of NA; (2) the addition of NA had a prohibiting impact on the threshold pore diameter and porosity of UHPC, which suggested that NA could be conducive to its pore structure; (3) the incorporation of NA led to a decline of 2.9–11.76% in the dry shrinkage of UHPC, which suggested that incorporating NA in a proper amount could reduce the risk of cracking and alleviate the dry shrinkage of UHPC; (4) the optimal amount of NA in UHPC was 1.0%, considering the effects of NA on workability, mechanical properties, microstructure, and the durability of UHPC. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
6. Design of Eco-friendly Ultra-high Performance Concrete with Supplementary Cementitious Materials and Coarse Aggregate
- Author
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Dong Guo, Zhou Wenjing, Liguo Wang, Taotao Feng, Jinyang Jiang, Chu Hongyan, and Fengjuan Wang
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Cement ,Aggregate (composite) ,Materials science ,0211 other engineering and technologies ,Modulus ,02 engineering and technology ,021001 nanoscience & nanotechnology ,Microstructure ,Compressive strength ,Flexural strength ,021105 building & construction ,General Materials Science ,Cementitious ,Composite material ,0210 nano-technology ,Porosity - Abstract
Aiming to investigate the mix design of eco-friendly UHPC with supplementary cementitious materials and coarser aggregates, we comprehensively studied the workability, microstructure, porosity, compressive strength, flexural strength, and Young’s modulus of UHPC. Relationship between compressive strength and Young’s modulus was obtained eventually. It is found that the compressive strength, flexural strength, and Young’s modulus of UHPC increase by 19.01%, 10.81%, and 5.99%, respectively, when 40wt% cement is replaced with supplementary cementitious materials. The relationship between compressive strength and Young’s modulus of UHPC is an exponential form.
- Published
- 2019
7. Effect of Graphene Oxide on Mechanical Properties and Durability of Ultra-High-Performance Concrete Prepared from Recycled Sand
- Author
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Chu Hongyan, Danqian Wang, Fengjuan Wang, Yu Zhang, Taotao Feng, and Liguo Wang
- Subjects
Materials science ,General Chemical Engineering ,microstructure ,0211 other engineering and technologies ,02 engineering and technology ,Raw material ,mechanical properties ,Article ,lcsh:Chemistry ,Flexural strength ,021105 building & construction ,Ultimate tensile strength ,recycled sand ,General Materials Science ,Composite material ,Porosity ,Elastic modulus ,ultra-high-performance concrete ,021001 nanoscience & nanotechnology ,Microstructure ,Durability ,Compressive strength ,lcsh:QD1-999 ,durability ,graphene oxide ,0210 nano-technology - Abstract
Ultra-high-performance concrete (UHPC) has been used as an advanced construction material in civil engineering because of its excellent mechanical properties and durability. However, with the depletion of the raw material (river sand) used for preparing UHPC, it is imperative to find a replacement material. Recycled sand is an alternative raw material for preparing UHPC, but it degrades the performance. In this study, we investigated the use of graphene oxide (GO) as an additive for enhancing the properties of UHPC prepared from recycled sand. The primary objective was to investigate the effects of GO on the mechanical properties and durability of the UHPC at different concentrations. Additionally, the impact of the GO additive on the microstructure of the UHPC prepared from recycled sand was analysed at different mixing concentrations. The addition of GO resulted in the following: (1) The porosity of the UHPC prepared from recycled sand was reduced by 4.45&ndash, 11.35%, (2) the compressive strength, flexural strength, splitting tensile strength, and elastic modulus of the UHPC prepared from recycled sand were enhanced by 8.24&ndash, 16.83%, 11.26&ndash, 26.62%, 15.63&ndash, 29.54%, and 5.84&ndash, 12.25%, respectively, (3) the resistance of the UHPC to penetration of chloride ions increased, and the freeze&ndash, thaw resistance improved, (4) the optimum mixing concentration of GO in the UHPC was determined to be 0.05 wt.%, according to a comprehensive analysis of its effects on the microstructure, mechanical properties, and durability of the UHPC. The findings of this study provide important guidance for the utilisation of recycled sand resources.
- Published
- 2020
8. Mechanical Properties and Environmental Evaluation of Ultra-High-Performance Concrete with Aeolian Sand
- Author
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Liguo Wang, Taotao Feng, Danqian Wang, Fengjuan Wang, and Chu Hongyan
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aeolian sand ,Materials science ,microstructure ,0211 other engineering and technologies ,Modulus ,Young's modulus ,02 engineering and technology ,mechanical properties ,lcsh:Technology ,Article ,symbols.namesake ,Flexural strength ,021105 building & construction ,General Materials Science ,Young’s modulus ,Composite material ,lcsh:Microscopy ,Ductility ,Porosity ,lcsh:QC120-168.85 ,ultra-high-performance concrete ,lcsh:QH201-278.5 ,lcsh:T ,021001 nanoscience & nanotechnology ,Microstructure ,Durability ,Compressive strength ,lcsh:TA1-2040 ,environmental assessment ,symbols ,lcsh:Descriptive and experimental mechanics ,lcsh:Electrical engineering. Electronics. Nuclear engineering ,lcsh:Engineering (General). Civil engineering (General) ,0210 nano-technology ,lcsh:TK1-9971 - Abstract
Ultra-high-performance concrete (UHPC) has received increasing attention in recent years due to its remarkable ductility, durability, and mechanical properties. However, the manufacture of UHPC can cause serious environmental issues. This work addresses the feasibility of using aeolian sand to produce UHPC, and the mix design, environmental impact, and mechanical characterization of UHPC are investigated. We designed the mix proportions of the UHPC according to the modified Andreasen and Andersen particle packing model. We studied the workability, microstructure, porosity, mechanical performance, and environmental impact of UHPC with three different water/binder ratios. The following findings were noted: (1) the compressive strength, flexural strength, and Young&rsquo, s modulus of the designed UHPC samples were in the ranges of 163.9&ndash, 207.0 MPa, 18.0&ndash, 32.2 MPa, and 49.3&ndash, 58.9 GPa, respectively, (2) the compressive strength, flexural strength, and Young&rsquo, s modulus of the UHPC increased with a decrease in water/binder ratio and an increase in the steel fibre content, (3) the compressive strength&ndash, Young&rsquo, s modulus correlation of the UHPC could be described by an exponential formula, (4) the environmental impact of UHPC can be improved by decreasing its water/binder ratio. These findings suggest that it is possible to use aeolian sand to manufacture UHPC, and this study promotes the application of aeolian sand for this purpose.
- Published
- 2020
9. Hydration process and microstructure evolution of low exothermic concrete produced with urea
- Author
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Chu Hongyan, Zhiqiang Yang, Jinyang Jiang, Zhiyong Liu, Ju Siyi, Fengjuan Wang, and Liguo Wang
- Subjects
Cement ,Materials science ,Recrystallization (geology) ,0211 other engineering and technologies ,020101 civil engineering ,02 engineering and technology ,Building and Construction ,Microstructure ,0201 civil engineering ,law.invention ,chemistry.chemical_compound ,Compressive strength ,Chemical engineering ,chemistry ,law ,Differential thermal analysis ,021105 building & construction ,Urea ,General Materials Science ,Cementitious ,Crystallization ,Civil and Structural Engineering - Abstract
In this paper, the feasibility of using urea as an additive to prepare low exothermic concrete is studied. The effect of different urea contents (0%, 5%, 10%, 15%) urea on the hydration process and the microstructure of the cementitious materials were investigated systematically. The experimental results show that urea has an obvious retarding effect on the early hydration of cement. The curve of the hydration heat release was significantly reduced and delayed with the urea content increased. The early strength of the concrete decreased significantly. Urea has almost no effect on the compressive strength of concrete at 28 days of age. The actual water-to-binder ratio is lowered, and the hygroscopicity and recrystallization of urea are the main reasons for shrinkage reduction and even micro-expansion of concrete. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) results show that urea does not change the cement hydration products. The total amount of chemically bound water and the degree of hydration of the sample show that urea has a greater inhibitory effect on early hydration of cement and less effect on hydration in a later stage. The results of mercury intrusion porosimetry (MIP) show that the total porosity of cement paste has a consistent trend with mechanical properties. When the content of urea in concrete exceeds 10%, white crystals appear inside of concrete. The Fourier Transform Infrared Spectrometry (FT-IR), Differential thermal analysis (TG-DSC) and SEM result show that crystalline product is produced by urea crystallization.
- Published
- 2020
10. Feasibility of producing ultra-high performance concrete with high elastic modulus by steel chips: An experimental study.
- Author
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Chu, Hongyan, Gao, Li, Qin, Jianjian, Jiang, Jinyang, and Wang, Fengjuan
- Subjects
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HIGH strength concrete , *ULTRASONIC testing , *PORE size distribution , *STEEL , *FLEXURAL strength , *ELASTIC modulus - Abstract
• UHPC with high elastic modulus was designed via MAA particle packing model. • Workability, microstructure, and mechanical strength of HMUHPC were studied. • Elastic modulus of HMUHPC ranged from 40.5 GPa to 49.3 GPa. • Optimal content of steel chips in HMUHPC was 50 wt%. Elastic modulus is one of the key parameters to weigh the stiffness of concrete members and structural design in civil engineering. Despite its excellent performance in durability and mechanical properties, ultra-high performance concrete (UHPC) is featured with relatively low elastic modulus, which prevents UHPC from being applied in a much larger scope. This study was conducted to explore the feasibility of preparing UHPC with high elastic modulus (HMUHPC) by using steel chips. The modified Andreasen and Andersen (MAA) particle packing model was used to design the initial mixture of HMUHPC. Based on this, some steps were followed to investigate the impacts of varying contents of steel chips on HMUHPC with regard to its mechanical properties, workability, and apparent density. In addition, attention was also paid to how steel chips affected the microstructure of HMUHPC and the ultrasonic pulse velocity (UPV) propagated in HMUHPC. It was found that: 1) Due to the addition of steel chips, there was an increase from 9.65% to 21.73%, 6.38% to 15.85%, 1.28% to 10.49%, and 3.11% to 16.44%, respectively, in the elastic modulus, compressive strength, flexural strength, and apparent density of HMUHPC; 2) The addition of steel chips could reduce the porosity of HMUHPC and optimize its pore size distribution; 3) Considering the effects of steel chips on HMUHPC regarding its microstructure, mechanical properties, and workability, the optimal content of steel chips in HMUHPC was 50 wt%. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
11. Feasibility of manufacturing self-compacting mortar with high elastic modulus by Al2O3 micro powder: A preliminary study.
- Author
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Chu, Hongyan, Shi, Wenfang, Wang, Qun, Gao, Li, and Wang, Danqian
- Subjects
- *
SELF-consolidating concrete , *ELASTIC modulus , *YOUNG'S modulus , *ULTRASONIC testing , *ALUMINUM oxide , *CEMENT composites , *MODULUS of elasticity - Abstract
• SCM with high elastic modulus was developed by using AMP. • Fluidity, microstructure, mechanical strength, and durability of SCM were studied. • DME of SCM was characterized via ultrasonic testing technology. • DME of SCM was increased by 4.37 ∼ 9.97% due to the addition of AMP. • Durability properties of SCM were markedly improved due to the addition of AMP. Cementitious composites are one of the most widely used building materials in civil engineering. However, their low Young's modulus cannot meet the requirements of long-span structures. This work carried out a feasibility study on producing self-compacting mortar (SCM) with high elastic modulus by using Al 2 O 3 micro powder (AMP). Effects of AMP on the workability, microstructure, mechanical properties, and durability properties of SCM were systematically investigated. The dynamic modulus of elasticity (DME) of SCM was characterized via ultrasonic testing technology. It was found that, 1) due to the addition of AMP, the porosity of SCM was reduced by 2.64 ∼ 13.64%, and the threshold pore diameter of SCM was decreased; 2) the flexural strength and compressive strength of SCM were increased by 4.40 ∼ 15.85% and 2.35 ∼ 14.33%, respectively, because of the incorporation of AMP; 3) the drying shrinkage of SCM was reduced by 6.46 ∼ 11.21%, and the chloride migration coefficient of SCM was decreased by 3.38 ∼ 18.64%, due to the addition of AMP; 4) the optimal content of AMP in SCM was 10%, considering the effects of AMP on the microstructure, mechanical properties, and durability properties of SCM; 5) it was feasible to produce SCM with high elastic modulus by using AMP, and the DME of SCM was increased by 4.37 ∼ 9.97%, because of the incorporation of AMP. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
12. Mechanical properties and microstructure of ultra-high-performance concrete with high elastic modulus.
- Author
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Chu, Hongyan, Gao, Li, Qin, Jianjian, Jiang, Jinyang, and Wang, Danqian
- Subjects
- *
HIGH strength concrete , *MICROSTRUCTURE , *FLEXURAL strength , *STRUCTURAL engineering , *ALUMINA composites , *COMPRESSIVE strength , *ELASTIC modulus - Abstract
• UHPC with high elastic modulus was design by MAA particle packing model. • Workability, microstructure, and mechanical strength of HEMUHPC were studied. • Elastic modulus of HEMUHPC ranged from 40.50 GPa to 47.13 GPa. • Relationship between elastic modulus and compressive strength was a power function. • Optimal content of alumina micro-powder in HEMUHPC was 10%. Elastic modulus is an important parameter in engineering structural design for evaluating the stiffness of concrete members. Ultra-high-performance concrete (UHPC) has excellent mechanical properties and durability, but the relatively low elastic modulus prohibits the widespread use of the UHPC. In this study, high elastic modulus UHPC (HEMUHPC) was designed according to Modified Andreasen and Andersen particle packing model proposed by Funk and Dinger. Effects of alumina micro-powder (the content of alumina is higher than 99%, and the particle size is lower than 100 μ m) on the workability, microstructure, and mechanical properties of HEMUHPC were systematically investigated. The reason for the improvement of elastic modulus of HEMUHPC was revealed by nano indentation test. It was found that, 1) the porosity and threshold pore diameter of HEMUHPC were reduced because of the addition of alumina micro-powder; 2) the flexural strength, compressive strength, and elastic modulus of HEMUHPC were increased by 3.54–11.23%, 8.89–22.83%, and 6.19–16.37%, respectively, due to the addition of alumina micro-powder; 3) the optimal content of alumina micro-powder was 10%, considering its effects on the workability, mechanical properties, and microstructure of HEMUHPC; 4) Nano indentation experiments showed that the elastic modulus of the alumina micro-powder was 90–135 GPa, which is much higher than the elastic modulus of hydration products of HEMUHPC, and thus the elastic modulus of the HEMUHPC matrix could be improved, due to the addition of alumina micro-powder. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
13. Mechanical Properties and Environmental Evaluation of Ultra-High-Performance Concrete with Aeolian Sand.
- Author
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Chu, Hongyan, Wang, Fengjuan, Wang, Liguo, Feng, Taotao, and Wang, Danqian
- Subjects
- *
YOUNG'S modulus , *CONCRETE , *COMPRESSIVE strength , *MICROSTRUCTURE - Abstract
Ultra-high-performance concrete (UHPC) has received increasing attention in recent years due to its remarkable ductility, durability, and mechanical properties. However, the manufacture of UHPC can cause serious environmental issues. This work addresses the feasibility of using aeolian sand to produce UHPC, and the mix design, environmental impact, and mechanical characterization of UHPC are investigated. We designed the mix proportions of the UHPC according to the modified Andreasen and Andersen particle packing model. We studied the workability, microstructure, porosity, mechanical performance, and environmental impact of UHPC with three different water/binder ratios. The following findings were noted: (1) the compressive strength, flexural strength, and Young's modulus of the designed UHPC samples were in the ranges of 163.9–207.0 MPa, 18.0–32.2 MPa, and 49.3–58.9 GPa, respectively; (2) the compressive strength, flexural strength, and Young's modulus of the UHPC increased with a decrease in water/binder ratio and an increase in the steel fibre content; (3) the compressive strength–Young's modulus correlation of the UHPC could be described by an exponential formula; (4) the environmental impact of UHPC can be improved by decreasing its water/binder ratio. These findings suggest that it is possible to use aeolian sand to manufacture UHPC, and this study promotes the application of aeolian sand for this purpose. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
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