scholarly journals Development of Ultra-Lightweight and High Strength Engineered Cementitious Composites

2021 ◽  
Vol 5 (4) ◽  
pp. 113
Author(s):  
Zhitao Chen ◽  
Junxia Li ◽  
En-Hua Yang
Keyword(s):  
Tensile Strain ◽  
High Strength ◽  
Matrix Composition ◽  
Cementitious Composites ◽  
Engineered Cementitious Composites ◽  
Micromechanical Properties ◽  
Matrix Fracture ◽  
The Matrix ◽  
Lightweight Filler ◽  
Tensile Strain Capacity

In this study, ultra-lightweight and high strength Engineered Cementitious Composites (ULHS-ECCs) are developed via lightweight filler incorporation and matrix composition tailoring. The mechanical, physical, and micromechanical properties of the resulting ULHS-ECCs are investigated and discussed. ULHS-ECCs with a density below 1300 kg/m3, a compressive strength beyond 60 MPa, a tensile strain capacity above 1%, and a thermal conductivity below 0.5 w/mK are developed. The inclusion of lightweight fillers and the variation in proportioning of the ternary binder can lead to a change in micromechanical properties, including the matrix fracture toughness and the fiber/matrix interface properties. As a result, the tensile strain-hardening performance of the ULHS-ECCs can be altered.

scholarly journals Using Green Supplementary Materials to Achieve More Ductile ECC

Materials ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 858 ◽  
Author(s):  
Yichao Wang ◽  
Zhigang Zhang ◽  
Jiangtao Yu ◽  
Jianzhuang Xiao ◽  
Qingfeng Xu
Keyword(s):  
Fracture Toughness ◽  
Tensile Strain ◽  
Tension Test ◽  
Construction And Demolition Waste ◽  
Demolition Waste ◽  
Strain Capacity ◽  
Fiber Bridging ◽  
Matrix Fracture ◽  
The Matrix ◽  
Tensile Strain Capacity

To improve the greenness and deformability of engineered cementitious composites (ECC), recycled powder (RP) from construction and demolition waste with an average size of 45 μm and crumb rubber (CR) of two particle sizes (40CR and 80CR) were used as supplements in the mix. In the present study, fly ash and silica sand used in ECC were replaced by RP (50% and 100% by weight) and CR (13% and 30% by weight), respectively. The tension test and compression test demonstrated that RP and CR incorporation has a positive effect on the deformability of ECC, especially on the tensile strain capacity. The highest tensile strain capacity was up to 12%, which is almost 3 times that of the average ECC. The fiber bridging capacity obtained from a single crack tension test and the matrix fracture toughness obtained from 3-point bending were used to analyze the influence of RP and CR at the meso-scale. It is indicated that the replacement of sand by CR lowers the matrix fracture toughness without decreasing the fiber bridging capacity. Accordingly, an explanation was achieved for the exceeding deformability of ECC incorporated with RP and CR based on the pseudo-strain hardening (PSH) index.

scholarly journals Development of Engineered Cementitious Composites Using Sea Sand and Metakaolin

2021 ◽  
Vol 8 ◽  
Author(s):  
Qiyao Yao ◽  
Zuo Li ◽  
Chenyu Lu ◽  
Linxin Peng ◽  
Yuejing Luo ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Fracture Energy ◽  
Tensile Strain ◽  
Chloride Ions ◽  
Silica Sand ◽  
Cementitious Composites ◽  
Engineered Cementitious Composites ◽  
Strain Capacity ◽  
Sea Sand ◽  
Tensile Strain Capacity

The present study investigates the possibility of using sea sand, instead of silica sand, in producing engineered cementitious composites (ECCs) and the optimal mix proportion, mechanical behavior, and erosive effect of chloride ions on sea sand ECCs (SECCs). Nine groups of SECC specimens were prepared based on the orthogonal test design, and these cured for the uniaxial tensile, uniaxial compression, and fracture energy tests. The roundness and sphericity of sea sand and silica sand were quantified by digital microscopy. The microstructure and composition of SECCs were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The mix proportions of SECCs with a tensile strain capacity more than 2% and a compressive strength more than 60 MPa were obtained. The factor analysis of these serial tests revealed that the contents of both fly ash and sea sand have a significant effect on the compressive strength and tensile strain capacity of SECCs. The fracture energy test revealed that the matrix fracture toughness of SECCs significantly increases with the increase in sea sand content. The XRD analysis revealed that the addition of metakaolin can enhance the ability of SECCs to bind chloride ions, and with the increase in chloride ion content, the ability of SECCs to bind chloride ions would improve. The results of the present study provide further evidence of the feasibility of using sea sand in the production of ECCs, in order to meet the requirements of diverse concrete components on ductility and durability.

Application of Tensile Strain Models to Multiple Grades of Pipelines

2014 ◽  
Author(s):  
Wenwei Zhang ◽  
Zhenyong Zhang ◽  
Jinyuan Zhang ◽  
Peng Yang
Keyword(s):  
Tensile Strain ◽  
Large Diameter ◽  
High Strength ◽  
Slope Movement ◽  
Experimental Database ◽  
Mine Subsidence ◽  
The Past ◽  
Discontinuous Permafrost ◽  
China National Petroleum Corporation ◽  
Tensile Strain Capacity

China National Petroleum Corporation (CNPC) has constructed large-diameter high-strength pipelines (X70 and X80) in the past decades in areas of seismic activities, mine subsidence, and slope movement using strain-based design (SBD) technology. More pipelines being constructed now traverse regions of active seismic activities, mine subsidence, slope movement, and discontinuous permafrost. CNPC is also interested in moving to linepipe grades higher than X80. In view of the recent development of various tensile strain models, work was undertaken to evaluate those models and determine the most appropriate models for current and future applications. In this paper, selected tensile strain models are reviewed and evaluated against an experimental database. The database of 80 tests from public-domain publications contains both full-scale pipe tests and curved wide plate tests with 46 tests from high strength pipes (X80 and above). The calculated tensile strain capacity from the selected models was compared with the test data. The models were evaluated and the applicability of the models to the linepipes of different strength levels was discussed.

Shrinkage Characteristics of Green Engineered Cementitious Composites with Varying Palm Oil Fuel Ash Contents and Water-Binder Ratios

2012 ◽  
Vol 626 ◽  
pp. 245-249 ◽  
Author(s):  
Nurdeen M. Altwair ◽  
M.A. Megat Johari ◽  
Syed Fuad Saiyid Hashim
Keyword(s):  
Palm Oil ◽  
Drying Shrinkage ◽  
Shrinkage Strain ◽  
Extensive Study ◽  
Cementitious Composites ◽  
Engineered Cementitious Composites ◽  
Palm Oil Fuel Ash ◽  
Fuel Ash ◽  
The Matrix ◽  
Oil Fuel

The present paper is a part of an extensive study on green palm oil fuel ash engineered cementitious composites conducted at Universiti Sains Malaysia. It specifically investigates the effects of waterbinder ratio (w/b) and palm oil fuel ash (POFA) on the drying shrinkage of engineered cementitious composites (ECCs). W/b values of 0.33, 0.36, and 0.38 were selected. ECC mixes were proportioned to have various ratios of POFA ranging from 0 to 1.2 from the mass of cement. The drying shrinkage measurements were taken at 4, 11, 18, 25, 57, and 90 days. The experimental results show that w/b has a significant effect on the drying shrinkage of the ECC mixtures. Drying shrinkage is remarkably reduced with a decrease in the w/b. The results also showed that drying shrinkage of the composites is considerably reduced when POFA is used in the matrix. The measured drying shrinkage strain at 90 days is only 920×10-6 µε to 1216×10-6 µε for ECC mixtures with high POFA content. The shrinkage strain of the ECC mixtures without POFA at 90 days is nearly 1597×10-6 µε to 1910×10-6 µε.

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