Effects of different grips and surface treatments of textile on measured direct tensile response of textile reinforced cementitious composites

2021 ◽  
Vol 278 ◽  
pp. 114689
Author(s):  
Van Doan Truong ◽  
Do Hyung Lee ◽  
Dong Joo Kim
2017 ◽  
Vol 52 (2) ◽  
pp. 121-134 ◽  
Author(s):  
Duy-Liem Nguyen ◽  
Duc-Kien Thai ◽  
Dong-Joo Kim

This research investigated the effects of direct tensile response on the flexural resistance of ultra-high-performance fiber-reinforced concretes by performing sectional analysis. The correlations between direct tensile and flexural response of ultra-high-performance fiber-reinforced concretes were investigated in detail for the development of a design code of ultra-high-performance fiber-reinforced concrete flexural members as follows: (1) the tensile resistance of ultra-high-performance fiber-reinforced concretes right after first-cracking in tension should be higher than one-third of the first-cracking strength to obtain the deflection-hardening if the ultra-high-performance fiber-reinforced concretes show tensile strain-softening response; (2) the equivalent bottom strain of flexural member at the modulus of rupture is always higher than the strain capacity of ultra-high-performance fiber-reinforced concretes in tension; (3) the softening part in the direct tensile response of ultra-high-performance fiber-reinforced concretes significantly affects their flexural resistance; and (4) the moment resistance of ultra-high-performance fiber-reinforced concrete girders is more significantly influenced by the post-cracking tensile strength rather than the tensile strain capacity. Moreover, the size and geometry effects should be carefully considered in predicting the moment capacity of ultra-high-performance fiber-reinforced concrete beams.


Author(s):  
M. Iqbal Khan ◽  
Shehab Mourad ◽  
Galal Fares ◽  
Wasim Abbass

One of the key factors affecting the successful production of strain-hardening cement-based composites (SHCC) is the nature of fine quartz aggregates. The elevated cost of SHCC preparation is considered as a limiting parameter. The incorporation of natural fine aggregates of different particle sizes can be one of the most cost-effective methods to produce SHCC locally. Two different types of local natural sands abundantly available in the Arabian Peninsula were used in the preparation of SHCC. The effect of these sands on the tensile response of SHCC under the effect of different strain rates was investigated. Three strain rates of 7.7x10-5, 1.5x10-4 and 1.5x10-3 s-1 were applied during the assessment of the direct tensile properties of SHCC samples made of natural sands. The results have shown that the use of natural sands provides an effective strain capacity. Microstructural analysis of SHCC mixtures has revealed the existence of two reaction mechanisms during PVA pullout of SHCC mixture with natural sands under direct tensile tension. Therefore, the incorporation of natural sands was proven to carry potential properties to SHCC mixtures that reduce their cost and encourage their production in a broad scale.


2020 ◽  
Vol 20 (1) ◽  
pp. 319-325
Author(s):  
Min-Jae Kim ◽  
Hong-Joon Choi ◽  
Booki Chun ◽  
Wonsik Shin ◽  
Doo-Yeol Yoo

This study aims to enhance the energy absorption capacity of cementitious composites with 2 vol.% of polyethylene fibers, by adjusting mixing ingredients and curing conditions. Ground blast furnace slag, cement kiln dust, limestone powder, and silica fume were incorporated, and two different curing conditions were applied: 72 h of curing at 90 ℃ and 120 h of curing at 40 ℃. Compressive strength test and direct tensile test were performed on 6 mixtures and the test results were compared with those of ultra-high-performance concrete and engineered cementitious composite specimens. The maximum compressive strength of the 6 mixtures was measured to be approximately 117 MPa. The higher cement replacement ratio of the other components resulted in a decrease in the compressive strength of the specimens cured at 90 ℃. In the direct tensile test, the specimens cured at 40 ℃ exhibited lower tensile strength than those cured at 90 ℃, but the strain capacity was increased by approximately 305% and reached 7.7%. This also resulted in an enhancement of the energy absorption capacity from 80%–292% because of the differences in micro-cracking and fracturing behaviors, such as an increase inthe number of micro-cracks and decrease in crack width.


Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3765
Author(s):  
Rubendran Loganathan ◽  
Bashar S. Mohammed

To avoid explosive spalling during elevated temperature, crumb rubber (CR) is being added to the manufacturing of engineered cementitious composites (ECC). However, the addition of CR particles adversely affects the mechanical properties of ECC. Therefore, to overcome this issue, nano-silica (NS) is added into rubberized ECC mixture as cementitious material additives. Response surface methodology (RSM) has been utilized to optimize the mixtures of the rubberized ECC with variables: CR (0, 2.5, and 5 vol.%), polyvinyl alcohol (PVA) fiber (0, 1, and 2 vol.%), NS (0, 1, and 2 vol.%), and fly ash (0, 25, and 50 vol.%). The experimentally measured responses are flexural strength, direct tensile strength, elastic modulus, Poisson’s ratio, creep, and drying shrinkage. Mathematical models to predict the targeted responses have been developed using RSM. As a result, a high correlation between the factors and responses has been exhibited by the developed models and the accuracy of fit, where less than 9.38% of the variation was found between the predicted and validated results. The experimental results revealed that the rubberized ECC with the incorporation of nano-silica exhibited a higher compressive strength, direct tensile strength, flexural strength, elastic modulus, Poisson’s ratio, and lower drying shrinkage.


2021 ◽  
Vol 8 ◽  
Author(s):  
Wei Fan ◽  
Yan Zhuge ◽  
Xing Ma ◽  
Christopher W.K. Chow ◽  
Nima Gorjian ◽  
...  

Strain hardening cementitious composites (SHCCs) with superior tensile strength and ductility have been utilized as an effective repair material. A corrosion-resistant binder, calcium aluminate cement (CAC)–ground granulated blast-furnace slag (GGBFS) blends, has been introduced into SHCC to expand its application in the concrete sewage network rehabilitation. As a repair material, the lightweight property is particularly favorable as it can broaden its functionality. This article presents a study on developing a novel lightweight CAC-GGBFS-blended SHCC using hollow glass microsphere (HGM), namely, HGMLW-SHCCs. The fine silica sand content was substituted with HGM at 25, 50, 75, and 100 vol% in HGMLW-SHCC. We examined flowability, density, uniaxial compressive behavior, direct tensile behavior, and pseudo strain-hardening indices. Microstructure analysis was also conducted to understand the meso-scale behavior of this new lightweight composite. The newly developed HGMLW-SHCC had a 28-day density of only 1756 kg/m3. Compressive and tensile strengths were determined in the range of 62.80–49.39 MPa and 5.81–4.19 MPa, respectively. All mixtures exhibited significant strain-hardening behavior. Even though the increased HGM content negatively affected the tensile strength of HGMLW-SHCC, it had a positive effect on its ductility. In addition, HGM can reduce crack width and tensile stress fluctuations significantly. The results showed that HGM was a promising material for producing strong and lightweight corrosion-resistant SHCCs to be used as a retrofitting material in the wastewater industry.


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