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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    

Effects of coarse and fine aggregates on long-term mechanical properties of sea sand recycled aggregate

《结构与土木工程前沿(英文)》 2021年 第15卷 第3期   页码 754-772 doi: 10.1007/s11709-021-0711-2

摘要: Typical effects of coarse and fine aggregates on the long-term properties of sea sand recycled aggregate concrete (SSRAC) are analyzed by a series of axial compression tests. Two different types of fine (coarse) aggregates are considered: sea sand and river sand (natural and recycled coarse aggregates). Variations in SSRAC properties at different ages are investigated. A novel test system is developed via axial compression experiments and the digital image correlation method to obtain the deformation field and crack development of concrete. Supportive results show that the compressive strength of SSRAC increase with decreasing recycled coarse aggregate replacement percentage and increasing sea sand chloride ion content. The elastic modulus of SSRAC increases with age. However, the Poisson’s ratio reduces after 2 years. Typical axial stress–strain curves of SSRAC vary with age. Generally, the effect of coarse aggregates on the axial deformation of SSRAC is clear; however, the deformation differences between coarse aggregate and cement mortar reduce by adopting sea sand. The aggregate type changes the crack characteristics and propagation of SSRAC. Finally, an analytical expression is suggested to construct the long-term stress–strain curve of SSRAC.

关键词: sea sand recycled aggregate concrete     recycled coarse aggregate replacement percentage     sea sand chloride ion content     long-term mechanical properties     stress–strain curve    

MICROBIAL NECROMASS WITHIN AGGREGATES STABILIZES PHYSICALLY-PROTECTED C RESPONSE TO CROPLAND MANAGEMENT

《农业科学与工程前沿(英文)》 2023年 第10卷 第2期   页码 198-209 doi: 10.15302/J-FASE-2023498

摘要:

● The contribution of fungal necromass C to SOC increased with aggregate sizes.

关键词: cropland management     microbial necromass     soil aggregates     soil carbon sequestration     soil organic matter    

Industrial bio-based plant aggregates as hygric and insulating construction materials for energy efficient

Yunhong Jiang, Mike Lawrence, Meng Zhang, Jiandong Cui

《化学科学与工程前沿(英文)》 2022年 第16卷 第10期   页码 1532-1532 doi: 10.1007/s11705-020-1960-7

摘要: In this paper, the bulk density, microstructure, porosity and pore size distribution of the selected aggregates, including hemp shiv, flax shiv, rape shiv and wheat straw, are fully studied due to these properties are highly related to their excellent characteristics and more or less linked to the properties of the final product. The scanning electron microscope results showed all the selected aggregates have a highly porous and complex hierarchical structure, whereas the arrangement of pores and the thickness of cell wall are significantly different among these aggregates. All the selected aggregates had a low bulk density ranging from 30 to 130 kg∙m and a high porosity between 75.81% and 88.74%. The thermal conductivity of the selected bio-aggregates ranged from 0.04 to 0.06 W∙m ∙K . The thermal conductivity of the selected aggregates was not only depending on the bulk density of the sample but also depending on the raw material. Hemp shiv, rape shiv and flax shiv were excellent hygric regulators with moisture buffer value ( ) ranging from 2.07 to 2.36 g∙m ∙%RH , whereas, wheat straw had a lower MBV value ranging from 1.76 to 1.97 g∙m ∙%RH . The results showed that particle size does not affect the value. The value increases linearly with bulk density.

关键词: bio-based aggregates     density     porosity     thermal conductivity     hygric properties    

Collaborative control of fine particles and ozone required in China for health benefit

《环境科学与工程前沿(英文)》 2023年 第17卷 第8期 doi: 10.1007/s11783-023-1692-2

摘要:

● Increased DAAO offsets 3/4 of the decrease of DAAP in 2013–2020.

关键词: Excess deaths     Long-term exposure     Fine particle     Ozone    

基于粉碎区控制的钻孔爆破岩石-炸药匹配方法

冷振东,卢文波,严鹏,陈明,胡英国

《中国工程科学》 2014年 第16卷 第11期   页码 28-35

摘要:

合理的炸药-岩石匹配关系对于提高炸药能量的有效利用率和改善破碎效果有着重要意义。传统上强调的波阻抗匹配理论并不合理,文章从爆破破碎机理出发,提出了一种岩石-炸药匹配的新方法,在保证相邻炮孔间岩石充分破碎的前提下,通过对粉碎区的合理控制来确定钻孔爆破最优的炸药性能参数。该方法可以直观地反映爆破破碎效果及能量有效利用率,可操作性强。考虑相邻炮孔爆炸荷载的联合作用,修正了钻孔爆破破坏分区计算模型。在此基础上,针对具体工程目标给出了混装炸药耦合装药条件下不同等级岩石的炸药性能匹配参数。

关键词: 钻孔爆破     粉碎区     岩石-炸药匹配     波阻抗匹配    

Retraction note to: Industrial bio-based plant aggregates as hygric and insulating construction materials

Yunhong Jiang, Mike Lawrence, Meng Zhang, Jiandong Cui

《化学科学与工程前沿(英文)》 doi: 10.1007/s11705-021-2039-9

Crushed rocks stabilized with organosilane and lignosulfonate in pavement unbound layers: Repeated load

Diego Maria BARBIERI, Inge HOFF, Chun-Hsing HO

《结构与土木工程前沿(英文)》 2021年 第15卷 第2期   页码 412-424 doi: 10.1007/s11709-021-0700-5

摘要: The creation of the new “Ferry-Free Coastal Highway Route E39” in southwest Norway entails the production of a remarkable quantity of crushed rocks. These resources could be beneficially employed as aggregates in the unbound courses of the highway itself or other road pavements present nearby. Two innovative stabilizing agents, organosilane and lignosulfonate, can significantly enhance the key properties, namely, resilient modulus and resistance against permanent deformation, of the aggregates that are excessively weak in their natural state. The beneficial effect offered by the additives was thoroughly evaluated by performing repeated load triaxial tests. The study adopted the most common numerical models to describe these two key mechanical properties. The increase in the resilient modulus and reduction in the accumulated vertical permanent deformation show the beneficial impact of the additives. Furthermore, a finite element model was created to simulate the repeated load triaxial test by implementing nonlinear elastic and plastic constitutive relationships.

关键词: organosilane     lignosulfonate     crushed rocks     pavement unbound layers     repeated load triaxial test     finite element analysis    

硗碛水电站大坝碎石土防渗料工程特性及土料设计

王寿根

《中国工程科学》 2004年 第6卷 第7期   页码 88-93

摘要:

硗碛水电站大坝高123 m,采用宽级配碎石土作为高土石坝心墙防渗料。对全料场进行了大量的室内工程特性试验研究以论证使用该材料的可行性,提出了设计及施工控制标准;选用代表性土料通过现场碾压试验验证该控制标准的合理性;对坝体、坝基进行了整体三维应力应变和渗流计算,分析了各种材料控制标准的合理性和共同作用下大坝的安全性;详实论述了防渗料工程特性研究方法、过程、成果,提出了心墙防渗料设计及施工控制标准。

关键词: 硗碛水电站     宽级配碎石土     防渗料     工程特性     碾压试验     土料设计    

Chloride diffusion in concrete with carbonated recycled coarse aggregates under biaxial compression

《结构与土木工程前沿(英文)》 2023年 第17卷 第4期   页码 637-648 doi: 10.1007/s11709-023-0902-0

摘要: Chloride attack on concrete structures is affected by the complex stress state inside concrete, and the effect of recycled aggregates renders this process more complex. Enhancing the chloride resistance of recycled concrete in a complex environment via carbonization facilitates the popularization and application of recycled concrete and alleviates the greenhouse effect. In this study, the chloride ion diffusion and deformation properties of recycled concrete after carbonization are investigated using a chloride salt load-coupling device. The results obtained demonstrate that the chloride ion diffusivity of recycled concrete first decreases and then increases as the compressive load increases, which is consistent with the behavior of concrete, in that it first undergoes compressive deformation, followed by crack propagation. Carbonation enhances the performance of the recycled aggregates and reduces their porosity, thereby reducing the chloride diffusion coefficient of the recycled concrete under different compressive load combinations. The variation in the chloride ion diffusivity of the carbonized recycled aggregate concrete with the load is consistent with a theoretical formula.

关键词: recycled concrete     carbonated recycled coarse aggregate     biaxial compression     chloride diffusion     stress level    

Properties of cement grout modified with ultra-fine slag

Sowmini GOPINATHAN, K B ANAND

《结构与土木工程前沿(英文)》 2018年 第12卷 第1期   页码 58-66 doi: 10.1007/s11709-017-0383-0

摘要: The purpose of the study is to obtain a cement grout with improved performance. The grout mixes of the present study contain cement, ultra-fine slag (UFS), super plasticizer and water. Properties like flowability, bleeding, compressive strength and shrinkage of cement grouts have been studied. Rheological parameters were also studied in order to explain the grout workability. The results show that, cement replacement with slag in grouts could reduce bleeding substantially without affecting the workability of the mixes. Introduction of slag enhanced the compressive strength and reduced shrinkage reasonably. Ultra-fine slag can be used as a supplementary cementitious material in cementitious grouts in order to improve the grout behavior.

关键词: cement grout     ultra-fine slag     flowability     bleeding     viscosity    

Confinement properties of circular concrete columns wrapped with prefabricated textile-reinforced fine

《结构与土木工程前沿(英文)》 doi: 10.1007/s11709-023-0955-0

摘要: This paper proposes an innovative column composed of a core column (including both reinforced concrete (RC) and plain concrete (PC) columns) and a prefabricated textile-reinforced fine concrete (TRC) shell. To study the confinement properties of TRC shells on this novel type of concrete column, 20 circular specimens, including 12 PC columns and 8 RC columns, were prepared for axial compressive tests. Four key parameters, including the column size, reinforcing ratio of the carbon textile, concrete strength, and stirrup spacing, were evaluated. The results indicated that the compressive properties of the columns were improved by increasing the reinforcing ratio of the textile layers. In the case of TRC-confined PC columns, the maximum improvement in the peak load was 56.3%, and for TRC-confined RC columns, the maximum improvement was 60.2%. Based on the test results, an analytical model that can be used to calculate the stress–strain curves of prefabricated TRC shell-confined concrete columns has been proposed. The calculated curves predicted by the proposed model agreed well with the test results.

关键词: textile-reinforced fine concrete     prefabricated shell     confined concrete column     confinement properties     stress–strain relationship    

Laboratory assessment of Alaska aggregates using Micro-Deval test

Jenny LIU,Sheng ZHAO,Anthony MULLIN

《结构与土木工程前沿(英文)》 2017年 第11卷 第1期   页码 27-34 doi: 10.1007/s11709-016-0359-5

摘要: Aggregates suitable for use in asphalt concrete (AC) pavement construction must meet durability criteria. Thus, it is critical to select appropriate tests to properly characterize aggregate durability. In Alaska, durability tests currently being used for aggregates in AC pavement include Los Angeles (LA) abrasion test, sulfate soundness test and Washington degradation test. However, there have long been concerns arising over Washington degradation test used as an acceptance tool, motivating pavement practitioners to seek more suitable alternatives. This paper presents a study to investigate the feasibility of using Micro-Deval test, commonly used in other states, to evaluate the durability of Alaskan aggregates in AC pavement as well as its potential to replace Washington degradation test. Micro-Deval test, Washington degradation test and other tests currently specified in Alaska were conducted on aggregates from 16 batches representing statewide sources. Based on the testing results, it is found that using Micro-Deval test for durability assessment of Alaska aggregates was feasible and reproducible, and a high potential was revealed to use Micro-Deval test to replace Washington degradation test in Alaska. It is recommended that Micro-Deval test be considered as an additional test for a certain period, but in the long run should be used along with current LA abrasion and sulfate soundness tests to provide a more desirable durability assessment of Alaska aggregates used in AC pavement.

关键词: aggregate durability     Washington degradation test     Micro-Deval test    

新世纪的精细化工

杨锦宗

《中国工程科学》 2002年 第4卷 第10期   页码 21-25

摘要:

指出精细化工是衡量化学工业水平的一个标志,提出并讨论了发展精细化工必须考虑的,包括环境保护、降低消耗、节约能源、合成关键技术、专用化技术、资源和科技创新等问题。

关键词: 环境保护     关键技术     节能     专用化技术     科技创新    

The use of fine portions from construction and demolition waste for expansive soil stabilization: A review

Mgboawaji Claude UJILE; Samuel Jonah ABBEY

《结构与土木工程前沿(英文)》 2022年 第16卷 第7期   页码 803-816 doi: 10.1007/s11709-022-0835-z

摘要: Construction and demolition waste (CDW) are the largest waste products in the world today and competes as a viable recycled additive material in place of natural aggregates. Due to the increase in compressive strength of different mix proportions of CDW, it is also considered for reuse in concrete and subbase construction. This study shows the effect of CDW in expansive soil stabilization. The chemical and mechanical properties of these materials have shown that they are capable of developing compressive strength properties for replacement of cement with significant reduction in carbon emission. The inherent compositional properties of recycled CDW compared in this review suggests that CDW have good filler properties in highly expansive soils. Mixtures of crushed brick and recycled aggregates characterised based on chemical properties of different replacement ratios suggests that CDW of good-quality aggregates reduces swell potential of expansive soils and increased mechanical strength in pavement construction.

关键词: mixed fine portions     construction and demolition waste     expansive soil     soil stabilization    

标题 作者 时间 类型 操作

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

Effects of coarse and fine aggregates on long-term mechanical properties of sea sand recycled aggregate

期刊论文

MICROBIAL NECROMASS WITHIN AGGREGATES STABILIZES PHYSICALLY-PROTECTED C RESPONSE TO CROPLAND MANAGEMENT

期刊论文

Industrial bio-based plant aggregates as hygric and insulating construction materials for energy efficient

Yunhong Jiang, Mike Lawrence, Meng Zhang, Jiandong Cui

期刊论文

Collaborative control of fine particles and ozone required in China for health benefit

期刊论文

基于粉碎区控制的钻孔爆破岩石-炸药匹配方法

冷振东,卢文波,严鹏,陈明,胡英国

期刊论文

Retraction note to: Industrial bio-based plant aggregates as hygric and insulating construction materials

Yunhong Jiang, Mike Lawrence, Meng Zhang, Jiandong Cui

期刊论文

Crushed rocks stabilized with organosilane and lignosulfonate in pavement unbound layers: Repeated load

Diego Maria BARBIERI, Inge HOFF, Chun-Hsing HO

期刊论文

硗碛水电站大坝碎石土防渗料工程特性及土料设计

王寿根

期刊论文

Chloride diffusion in concrete with carbonated recycled coarse aggregates under biaxial compression

期刊论文

Properties of cement grout modified with ultra-fine slag

Sowmini GOPINATHAN, K B ANAND

期刊论文

Confinement properties of circular concrete columns wrapped with prefabricated textile-reinforced fine

期刊论文

Laboratory assessment of Alaska aggregates using Micro-Deval test

Jenny LIU,Sheng ZHAO,Anthony MULLIN

期刊论文

新世纪的精细化工

杨锦宗

期刊论文

The use of fine portions from construction and demolition waste for expansive soil stabilization: A review

Mgboawaji Claude UJILE; Samuel Jonah ABBEY

期刊论文