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experimental study for optimization of high range water reducing superplasticizer in self compacting concrete

Rahul DUBEY, Pardeep KUMAR

《结构与土木工程前沿（英文）》 2013年 第7卷 第1期   页码 62-71 doi: 10.1007/s11709-013-0192-z

摘要： Concrete is extensively used construction material in the infrastructure development industry. With increase in technical knowhow, the need of research for high performance concretes such as self-compacting concrete (SCC) has increased in the last decade. The adaptability of SCC is due to its fluidic behavior in fresh state. However, to develop SCC using indigenous materials, the lack of standardized mix design procedures is the biggest impediment. Although with the advent of chemical admixtures, it is possible to achieve concrete with high fluidity, but at the same time durability issues require more attention. To have these fresh state properties SCC mixes are typically designed with high powder contents, and chemical admixtures. Proportioning and optimization of these materials is a key issue in the mix design of SCC. This paper focuses mainly on experimental study to optimize dosages of superplasticizer for mortar of SCC and then in concrete mixture itself.

关键词： self-compacting concrete (SCC)     fresh properties     superplasticizer     optimization     compressive strength    

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Effects of microfine aggregate in manufactured sand on bleeding and plastic shrinkage cracking of concrete

Branavan ARULMOLY; Chaminda KONTHESINGHA; Anura NANAYAKKARA

《结构与土木工程前沿（英文）》 2022年 第16卷 第11期   页码 1453-1473 doi: 10.1007/s11709-022-0877-2

摘要： Construction industries have started to utilize manufactured sand (MS) as an effective alternative for river sand in concrete. High-grade parent rocks are crushed to obtain MS, which also produces a considerable amount of microfine aggregate (MFA). The higher percentage of MFA could lead to both positive and negative effects on the performance of cement-based mixes. This research was done to examine the influence of varying MFA levels, specifically 0%, 3%, 6%, 9%, and 12% (by weight) as the partial replacements of MS on bleeding and plastic shrinkage cracking of concrete. In addition to the varying MFA levels, some concrete mixes also included fly ash (FA) and superplasticizer to investigate the effect of free-water content in the mixes. The bleeding test data were taken as on-site measurements, while the cracks from the plastic shrinkage cracking test were evaluated using an image processing technique. The results concluded that the MFA replacements and the effective water-to-cement ratio have a significant effect on the selected concrete properties. With the increasing replacement levels, cumulative bleeding and crack initiation life gradually decreased, while a progressive increase was observed for crack width, crack length, and crack area.

关键词： manufactured sand     fresh concrete     microfines     admixtures     shrinkage     cracking    

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METAGENOMICS COMBINED WITH HIGH-THROUGHPUT SEQUENCING REVEALS THE METHANOGENIC POTENTIAL OF FRESH CORN

《农业科学与工程前沿（英文）》 2023年 第10卷 第3期   页码 403-423 doi: 10.15302/J-FASE-2022471

摘要：

● Methane production from fresh straw was 7.50% higher than dry straw.

关键词： fresh corn straw     high solid anaerobic digestion     metagenomics     microbial communities     thermophilic    

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Fresh and hardened properties of high-strength concrete incorporating byproduct fine crushed aggregate

Dammika P. K. WELLALA, Ashish Kumer SAHA, Prabir Kumar SARKER, Vinod RAJAYOGAN

《结构与土木工程前沿（英文）》 2021年 第15卷 第1期   页码 124-135 doi: 10.1007/s11709-020-0673-9

摘要： This paper presents the fresh and hardened properties of high-strength concrete comprising byproduct fine crushed aggregates (FCAs) sourced from the crushing of three different types of rocks, namely granophyre, basalt, and granite. The lowest void contents of the combined fine aggregates were observed when 40% to 60% of natural sand is replaced by the FCAs. By the replacement of 40% FCAs, the slump and bleeding of concrete with a water-to-cement ratio of 0.45 decreased by approximately 15% and 50%, respectively, owing to the relatively high fines content of the FCAs. The 28 d compressive strength of concrete was 50 MPa when 40% FCAs were used. The slight decrease in tensile strength from the FCAs is attributed to the flakiness of the particles. The correlations between the splitting tensile and compressive strengths of normal concrete provided in the AS 3600 and ACI 318 design standards are applicable for concrete using the FCAs as partial replacement of sand. The maximum 56 d drying shrinkage is 520 microstrains, which is significantly less than the recommended limit of 1000 microstrains by AS 3600 for concrete. Therefore, the use of these byproduct FCAs can be considered as a sustainable alternative option for the production of high-strength green concrete.

关键词： fine crushed aggregates     quarry dust     compressive strength     splitting tensile strength     drying shrinkage    

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Recycled glass replacement as fine aggregate in self-compacting concrete

Yasser SHARIFI, Mahmoud HOUSHIAR, Behnam AGHEBATI

《结构与土木工程前沿（英文）》 2013年 第7卷 第4期   页码 419-428 doi: 10.1007/s11709-013-0224-8

摘要： With increasing environmental pressure to reduce solid waste and to recycle as much as possible, the concrete industry has adopted a number of methods to achieve this goal by replacement of waste glass with concrete composition materials. Due to differences in mixture design, placement and consolidation techniques, the strength and durability of Self Compacting Concrete (SCC) may be different than those of conventional concrete. Therefore, replacement of waste glass with fine aggregate in SCC should deeply be investigated compared to conventional concretes. The aim of the present study is to investigate the effect of glass replacement with fine aggregate on the SCC properties. In present study, fine aggregate has been replaced with waste glass in six different weight ratios ranging from 0% to 50%. Fresh results indicate that the flow-ability characteristics have been increased as the waste glass incorporated to paste volume. Nevertheless, compressive, flexural and splitting strengths of concrete containing waste glass have been shown to decrease when the content of waste glass is increased. The strength reduction of concrete in different glass replacement ratios is not remarkable, thus it can be produced SCC with waste glass as fine aggregate in a standard manner.

关键词： Self Compacting Concrete (SCC)     recycle glass     fine aggregate     fresh and hardened properties    

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Fresh and hardened properties of high-performance fiber-reinforced concrete containing fly ash and rice

Nguyen-Trong HO; Viet Quoc DANG; Minh-Hieu NGUYEN; Chao-Lung HWANG; Trong-Phuoc HUYNH

《结构与土木工程前沿（英文）》 2022年 第16卷 第12期   页码 1621-1632 doi: 10.1007/s11709-022-0884-3

摘要： Although fibers are used only infrequently as an additive in concrete in the construction industry, fiber-enhanced concrete is known to provide a wide range of advantages over conventional concrete. The main objective of this study was to investigate the influences of fiber type and content on the mechanical properties and durability of high-performance fiber-reinforced concrete (HPFRC) designed using a novel densified mixture design algorithm with fly ash and rice husk ash. Three types of fiber, including polypropylene (PP) fiber, steel fiber (SF), and hybrid fiber (HF), were considered. Based on the results, the inclusion of fibers decreased HPFRC flowability, regardless of fiber type. Although the compressive strength of HPFRC with 1.6% PP fiber content was 11.2% below that of the reference HPFRC specimen at 91 d of curing age, the 91-d compressive strengths of both SF and HF-enhanced HPFRC specimens were significantly better than that of the reference HPFRC specimen. Furthermore, the HPFRC specimens incorporating SF and HF both exhibited better splitting tensile and flexural strengths as well as less drying shrinkage than the HPFRC specimens incorporating PP fiber. However, the fiber-enhanced specimens, especially those with added SF, registered less surface electrical resistivity and greater vulnerability to chloride ion penetration than the reference HPFRC specimen.

关键词： high-performance fiber-reinforced concrete     fly ash     rice husk ash     durability     mechanical strength    

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Energy rebound effect in China’s manufacturing sector: Fresh evidence from firm-level data

《工程管理前沿（英文）》   页码 439-451 doi: 10.1007/s42524-022-0210-8

摘要： The rebound effect refers to the phenomenon that individuals tend to consume more energy in the face of energy efficiency improvement, which reduces the expected energy-saving effect. Previous empirical studies on the rebound effect of regions and sectors do not provide microscopic evidence. To fill this gap, we use China’s firm-level data to estimate the rebound effect in China’s manufacturing subsectors, providing a detailed picture of China’s rebound effect across different sectors and different regions in 2001–2008. Results show that a partial rebound effect robustly appears in all industries, and the disparity between sectors is quite broad, ranging from 43.2% to 96.8%. As for the dynamic rebound effect of subsectors, most subsectors present an upward trend, whereas few subsectors show a clear downward trend. As a whole, the declined trend of the rebound effect is driven by the descent of minority sectors with high energy consumption and high energy-saving potential. In addition, we find that the disparity of the rebound effect across sectors is more significant than that across regions.

关键词： energy rebound effect     energy efficiency     manufacturing sector     firm-level data     China    

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METABOLIC AND TRANSCRIPTOME ANALYSIS REVEALS METABOLITE VARIATION AND FLAVONOID REGULATORY NETWORKS IN FRESH

《农业科学与工程前沿（英文）》 2021年 第8卷 第2期

摘要：

Metabolites, especially secondary metabolites, are very important in the adaption of tea plants and the quality of tea products. Here, we focus on the seasonal variation in metabolites of fresh tea shoots and their regulatory mechanism at the transcriptional level. The metabolic profiles of fresh tea shoots of 10 tea accessions collected in spring, summer, and autumn were analyzed using ultra-performance liquid chromatography coupled with quadrupole-obitrap mass spectrometry. We focused on the metabolites and key genes in the phenylpropanoid/flavonoid pathway integrated with transcriptome analysis. Multivariate statistical analysis indicates that metabolites were distinctly different with seasonal alternation. Flavonoids, amino acids, organic acids and alkaloids were the predominant metabolites. Levels of most key genes and downstream compounds in the flavonoid pathway were lowest in spring but the catechin quality index was highest in spring. The regulatory pathway was explored by constructing a metabolite correlation network and a weighted gene co-expression network.

 

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Recycling combustibles from aged municipal solid wastes (MSW) to improve fresh MSW incineration in Shanghai

Dezhen CHEN, Zhenzhen GUAN, Guangyu LIU, Tong ZHU, Gongming ZHOU,

《环境科学与工程前沿（英文）》 2010年 第4卷 第2期   页码 235-243 doi: 10.1007/s11783-010-0016-5

摘要： Aged municipal solid wastes (MSW) excavated from landfills and dumpsites were characterized to analyze their fraction composition, moisture content, and lower heat value (LHV). The necessity and feasibility of recycling combustibles from aged MSW to improve the incineration of fresh MSW were investigated. The results showed that combustibles in aged MSW were easily separated from other components and than LHV of the separated combustibles are higher than 11000 kJ/kg. The fresh MSW are of high moisture contents with average LHV below 6500 kJ/kg, making their stable combustion difficult to maintain in MSW incinerators. For both fresh MSW and aged MSW, plastics are the main contributor to their LHV. To improve incineration of fresh MSW that are characterized with low LHV, combustibles separated from aged MSW were made into refuse derived fuel (RDF) pellets and were then added to fresh MSW by 2% wt.– 5% wt. LHV variation and air supply resistance change of the MSW layer on the incinerator grate caused by the addition of RDF was checked, and no significant changes were found. No obvious difference was observed for the ‘burn-out time’ between RDF pellets and fresh MSW either. RDF made from aged MSW combustibles is found to be a promising auxiliary fuel to improve the incineration of fresh MSW, and aged MSW from old landfill cells and dumpsites can be finally disposed of jointly with fresh MSW by recycling combustible from the former to be co-incinerated with the latter in the incineration plants.

关键词： aged municipal solid wastes (MSW)     fresh MSW     lower heat value (LHV)     combustibles     refuse derived fuel (RDF)     incineration    

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Effects of fiber curvature on the microstructure of the interfacial transition zone in fresh concrete

CHEN Huisu, SUN Wei, ZHAO Qingxin, L. J. Sluys, P. Stroeven

《结构与土木工程前沿（英文）》 2007年 第1卷 第1期   页码 99-106 doi: 10.1007/s11709-007-0010-6

摘要： The study on the interfacial transition zone (ITZ) of concrete has received lots of attention in the last decade. However, no information is available on the influence of the curvature of a rigid surface on the microstructure of ITZ. This paper employed computer simulation technology to study the influence of fiber curvature on the initial microstructure of ITZ in concrete. For the sake of simplification, the investigation was first focused on the mono-size spherical particle packing system around a cylindrical fiber with different diameters. An algorithm of serial cylindrical sectioning was developed. The curve of the solid volume fraction versus the distance to the surface of the fiber was used as a parameter to characterize the microstructure of the ITZ. Then, the influence of the ratio of fiber diameter to particle diameter on the initial ITZ s microstructure was studied. These curves were compared with the ones from flat aggregate surface on which mono-size spherical particles were packed. Furthermore, the multi-size spherical particles system was further investigated. The simulation results demonstrate that no matter whether the spherical particles system is mono-size or multi-size, the fresh ITZ s microstructure is irrelevant to the curvature of the fiber. The shape of the curve of solid volume fraction versus the distance from the surface of the fiber is similar to that around a flat aggregate surface. In all cases, the horizontal coordinates of the first peak of the curves are located at around half the mean weight diameter of the particles. The thickness of ITZ reduces slightly with the decrease in water/cement ratio. Therefore, one may use the ITZ s microstructure around a flat aggregate surface to represent the ITZ s microstructure around a cylindrical fiber in the fresh state, and vice versa.

关键词： diameter     initial microstructure     influence     surface     spherical particle    

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Anaerobic treatment of fresh leachate from a municipal solid waste incinerator by upflow blanket filter

Pinjing HE, Min LI, Suyun XU, Liming SHAO,

《环境科学与工程前沿（英文）》 2009年 第3卷 第4期   页码 404-411 doi: 10.1007/s11783-009-0149-6

摘要： This paper describes the feasibility of fresh leachate treatment by an upflow blanket filter (UBF). Through dilution and partial effluent recycling, the organic loading rates increased from 0.51to 14.56kg COD/(m·d), meanwhile the corresponding hydraulic retention time decreased from 9.0d to 3.6d. The reactor was able to achieve steady-state within 80d. Based on the distribution of COD fluxes in the process, it was concluded that anabolism was the main pathway of COD removal in the initial phase (1―33d), accounting for 57%―85% of total COD removed. As the anaerobic consortium of bacteria reached steady-state (after 70―86d), the majority of COD removed was transformed into methane, because the specific methane yield was close to the theoretical value (0.36L CH/(g COD)).

关键词： distribution of COD fluxes     effluent recycling     leachate     methane yield     organic loading rate     upflow blanket filter    

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METABOLIC AND TRANSCRIPTOME ANALYSIS REVEALS METABOLITE VARIATION AND FLAVONOID REGULATORY NETWORKS IN FRESH

Chen-Kai JIANG, De-Jiang NI, Ming-Zhe YAO, Jian-Qiang MA, Liang CHEN

《农业科学与工程前沿（英文）》   页码 215-230 doi: 10.15302/J-FASE-2021382

摘要： Metabolites, especially secondary metabolites, are very important in the adaption of tea plants and the quality of tea products. Here, we focus on the seasonal variation in metabolites of fresh tea shoots and their regulatory mechanism at the transcriptional level. The metabolic profiles of fresh tea shoots of 10 tea accessions collected in spring, summer, and autumn were analyzed using ultra-performance liquid chromatography coupled with quadrupole-obitrap mass spectrometry. We focused on the metabolites and key genes in the phenylpropanoid/flavonoid pathway integrated with transcriptome analysis. Multivariate statistical analysis indicates that metabolites were distinctly different with seasonal alternation. Flavonoids, amino acids, organic acids and alkaloids were the predominant metabolites. Levels of most key genes and downstream compounds in the flavonoid pathway were lowest in spring but the catechin quality index was highest in spring. The regulatory pathway was explored by constructing a metabolite correlation network and a weighted gene co-expression network.

关键词： harvest season     metabolites     tea shoots     transcriptomics     untargeted metabolomics    

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生鲜农产品冷链储运技术装备发展研究

杨天阳,田长青,刘树森

《中国工程科学》 2021年 第23卷 第4期   页码 37-44 doi: 10.15302/J-SSCAE-2021.04.005

摘要：

冷链储运技术装备是维持生鲜农产品品质并提高流通效率的重要途径，对于保障食品安全、提高农业收入具有重要意义。本文在分析我国冷链储运技术装备需求的基础上，梳理了我国冷链储运技术装备的发展现状，总结了我国生鲜农产品冷链储运技术装备相比于发达国家存在的差距与问题；基于德尔菲法与实地调研，研判了我国生鲜农产品冷链储运技术装备发展的关键技术、重点任务、重大工程。针对我国生鲜农产品冷链储运技术装备存在的产地专业化预冷设施匮乏、冷藏运输装备匮乏、速冻技术装备落后、关键技术研发滞后、冷冻冷藏设施建设不规范、冷链基础设施建设不足等问题，提出了发展规划“三步走”技术路线，以期我国生鲜农产品冷链储运技术装备到 2025 年能够初步实现高效化与标准化，到 2035 年能够实现信息化与智能化，到 2050 年能够实现智慧化与无人化。

关键词： 生鲜农产品，冷链储运技术，冷链装备，德尔菲法    

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Slender reinforced concrete shear walls with high-strength concrete boundary elements

《结构与土木工程前沿（英文）》 2023年 第17卷 第1期   页码 138-151 doi: 10.1007/s11709-022-0897-y

摘要： Reinforced concrete structural walls are commonly used for resisting lateral forces in buildings. Owing to the advancements in the field of concrete materials over the past few decades, concrete mixes of high compressive strength, commonly referred to as high-strength concrete (HSC), have been developed. In this study, the effects of strategic placement of HSC on the performance of slender walls were examined. The finite-element model of a conventional normal-strength concrete (NSC) prototype wall was validated using test data available in extant studies. HSC was incorporated in the boundary elements of the wall to compare its performance with that of the conventional wall at different axial loads. Potential reductions in the reinforcement area and size of the boundary elements were investigated. The HSC wall exhibited improved strength and stiffness, and thereby, allowed reduction in the longitudinal reinforcement area and size of the boundary elements for the same strength of the conventional wall. Cold joints resulting from dissimilar concrete pours in the web and boundary elements of the HSC wall were modeled and their impact on behavior of the wall was examined.

关键词： slender walls     high-strength concrete     rectangular and barbell-shaped walls     cold joints    

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Stability of three-dimensional printable foam concrete as function of surfactant characteristics

《结构与土木工程前沿（英文）》   页码 935-947 doi: 10.1007/s11709-023-0964-z

摘要： Extrudability is one of the most critical factors when designing three-dimensional printable foam concrete. The extrusion process likely affects the foam stability which necessitates the investigation into surfactant properties particularly for concrete mixes with high foam contents. Although many studies have been conducted on traditional foam concrete in this context, studies on three-dimensional printed foam concrete are scarce. To address this research gap, the effects of surfactant characteristics on the stability, extrudability, and buildability of three-dimensional printed foam concrete mixes with two design densities (1000 and 1300 kg/m3) using two different surfactants and stabilizers (synthetic-based sodium lauryl sulfate stabilized with carboxymethyl cellulose sodium salt, and natural-based hingot surfactant stabilized with xanthan gum) were investigated in this study. Fresh density tests were conducted before and after the extrusion to determine stability of the foam concrete. The results were then correlated with surfactant qualities, such as viscosity and surface tension, to understand the importance of key parameters in three-dimensional printing of foam concrete. Based on the experimental results, surfactant solu1tion with viscosity exceeding 5 mPa·s and surface tension lower than 31 mN/m was recommended to yield stable three-dimensional printable foam concrete mixes. Nevertheless, the volume of foam in the mix significantly affected the printability characteristics. Unlike traditional foam concrete, the variation in the stabilizer concentration and density of concrete were found to have insignificant effect on the fresh-state-characteristics (slump, slump flow, and static yield stress) and air void microstructure of the stable mixes.

关键词： foam concrete     3D printable concrete     stability     rheology     air void microstructure    

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标题 作者 时间 类型 操作

experimental study for optimization of high range water reducing superplasticizer in self compacting concrete

Rahul DUBEY, Pardeep KUMAR

期刊论文

Effects of microfine aggregate in manufactured sand on bleeding and plastic shrinkage cracking of concrete

Branavan ARULMOLY; Chaminda KONTHESINGHA; Anura NANAYAKKARA

期刊论文

METAGENOMICS COMBINED WITH HIGH-THROUGHPUT SEQUENCING REVEALS THE METHANOGENIC POTENTIAL OF FRESH CORN

期刊论文

Fresh and hardened properties of high-strength concrete incorporating byproduct fine crushed aggregate

Dammika P. K. WELLALA, Ashish Kumer SAHA, Prabir Kumar SARKER, Vinod RAJAYOGAN

期刊论文

Recycled glass replacement as fine aggregate in self-compacting concrete

Yasser SHARIFI, Mahmoud HOUSHIAR, Behnam AGHEBATI

期刊论文

Fresh and hardened properties of high-performance fiber-reinforced concrete containing fly ash and rice

Nguyen-Trong HO; Viet Quoc DANG; Minh-Hieu NGUYEN; Chao-Lung HWANG; Trong-Phuoc HUYNH

期刊论文

Energy rebound effect in China’s manufacturing sector: Fresh evidence from firm-level data

期刊论文

METABOLIC AND TRANSCRIPTOME ANALYSIS REVEALS METABOLITE VARIATION AND FLAVONOID REGULATORY NETWORKS IN FRESH

期刊论文

Recycling combustibles from aged municipal solid wastes (MSW) to improve fresh MSW incineration in Shanghai

Dezhen CHEN, Zhenzhen GUAN, Guangyu LIU, Tong ZHU, Gongming ZHOU,

期刊论文

Effects of fiber curvature on the microstructure of the interfacial transition zone in fresh concrete

CHEN Huisu, SUN Wei, ZHAO Qingxin, L. J. Sluys, P. Stroeven

期刊论文

Anaerobic treatment of fresh leachate from a municipal solid waste incinerator by upflow blanket filter

Pinjing HE, Min LI, Suyun XU, Liming SHAO,

期刊论文

METABOLIC AND TRANSCRIPTOME ANALYSIS REVEALS METABOLITE VARIATION AND FLAVONOID REGULATORY NETWORKS IN FRESH

Chen-Kai JIANG, De-Jiang NI, Ming-Zhe YAO, Jian-Qiang MA, Liang CHEN

期刊论文

生鲜农产品冷链储运技术装备发展研究

杨天阳,田长青,刘树森

期刊论文

Slender reinforced concrete shear walls with high-strength concrete boundary elements

期刊论文

Stability of three-dimensional printable foam concrete as function of surfactant characteristics

期刊论文