Effect of calcium sulfoaluminate-based expansive agent on rate dependent pullout behavior of straight steel fiber embedded in UHPC

2019 ◽  
Vol 122 ◽  
pp. 196-211 ◽  
Author(s):  
Doo-Yeol Yoo ◽  
Booki Chun ◽  
Jae-Jin Kim
Keyword(s):  
Steel Fiber ◽  
Calcium Sulfoaluminate ◽  
Rate Dependent ◽  
Expansive Agent

scholarly journals Shrinkage and Mechanical Properties of Self-Compacting SFRC With Calcium-Sulfoaluminate Expansive Agent

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 588 ◽  
Author(s):  
Changyong Li ◽  
Pengran Shang ◽  
Fenglan Li ◽  
Meng Feng ◽  
Shunbo Zhao
Keyword(s):  
Mechanical Properties ◽  
Steel Fiber ◽  
Volume Fraction ◽  
Cementitious Materials ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
Steel Fiber Reinforced Concrete ◽  
Volume Stability ◽  
Calcium Sulfoaluminate ◽  
Expansive Agent

With the premise of ensuring workability on a fresh mixture, the volume stability of hardened self-compacting steel fiber reinforced concrete (SFRC) becomes an issue due to the content of cementitious materials increased with the volume fraction of steel fiber. By using the expansive agent to reduce the shrinkage deformation of self-compacting SFRC, the strength reduction of hardened self-compacting SFRC is another issue. To solve these issues, this paper performed an experimental investigation on the workability, shrinkage, and mechanical properties of self-compacting SFRC compared to the self-compacting concrete (SCC) with or without an expansive agent. The calcium-sulfoaluminate expansive agent with content optimized to be 10% mass of binders and the steel fiber with a varying volume fraction from 0.4% to 1.2% were selected as the main parameters. The mix proportion of self-compacting SFRC with expansive agent was designed by the direct absolute volume method, of which the steel fibers are considered to be the distributed coarse aggregates. Results showed that rational high filling and passing ability of fresh self-compacting SFRC was ensured by increasing the binder to coarse-aggregate ratio and the sand ratio in the mix proportions; the autogenous and drying shrinkages of hardened self-compacting SFRC reduced by 22.2% to 3.2% and by 18.5% to 7.3% compared to those of the SCC without expansive agent at a curing age of 180 d, although the expansion effect of expansive agent decreased with the increasing volume fraction of steel fiber; the mechanical properties, including the compressive strength, the splitting tensile strength, and the modulus of elasticity increased with the incorporation of an expansive agent and steel fibers, which met the design requirements.

Experimental Study on Rate-Dependent of the Bending Tensile Properties for Steel Fiber Reinforced Concrete

2011 ◽  
Vol 71-78 ◽  
pp. 1083-1089
Author(s):  
Zhang Luo
Keyword(s):  
Reinforced Concrete ◽  
Flexural Strength ◽  
Strain Rate ◽  
Tensile Properties ◽  
Steel Fiber ◽  
Fiber Reinforced Concrete ◽  
Test Machine ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Rate Dependent

Extensive experimental research has been done on rate-dependent properties normal concrete, but very little on the tensile properties of steel fiber reinforced concrete (SFRC). In this article, based on a high-speed Instron servo-controlled hydraulic materials test machine is adopted to investigate the strain rate-dependent properties of bending tensile properties for SFRC. The scheme of experiment, the works of specimens fabricating and the processes of both loading and measuring were introduced. A total of 30 beam specimens are tested. The steel fiber content is varied: 0%, 1.0%, 2.0%, 3.0% and 4.0% by volume. The experimental results were analyzed. The emphasis is put on the study of the flexural strength changes of SFRC under different strain rates. It is discovered that, with the improvement of the strain rate, increasing strength of SFRC is very obvious. While the strain rate increases from 1.4×10-4s-1 to 0.53×10-4s-1, the flexural strength increasing around 30%.

scholarly journals Fasteners in Steel Fiber Reinforced Concrete Subjected to Increased Loading Rates

Fibers ◽  
2018 ◽  
Vol 6 (4) ◽  
pp. 93 ◽  
Author(s):  
Boglárka Bokor ◽  
Máté Tóth ◽  
Akanshu Sharma
Keyword(s):  
Reinforced Concrete ◽  
Static Loading ◽  
Steel Fiber ◽  
Plain Concrete ◽  
Fiber Reinforced Concrete ◽  
Fiber Reinforced ◽  
Steel Fiber Reinforced Concrete ◽  
Loading Rates ◽  
Rate Dependent ◽  
Ultimate Resistance

Increased loading rates on fasteners may be caused by high ground accelerations as a consequence of e.g., nuclear explosions, earthquakes or car collisions. It was concluded by Hoehler et al. (2006) that fasteners under rapid loading rates show an increased ultimate resistance in the concrete dominant failure modes or the ultimate resistance is at least as large as under quasi-static loading. Due to the increased demand on using fasteners in steel fiber reinforced concrete (SFRC), it is intended to show how the ultimate concrete cone capacity of fasteners changes under higher than quasi-static loading rate in normal plain concrete (PC) and in SFRC. This paper presents the results of an extensive experimental program carried out on single fasteners loaded in tension in normal plain concrete and in SFRC. The test series were conducted using a servo-hydraulic loading cylinder. The tests were performed in displacement control with a programmed ramp speed of 1, 100, 1000, and 3500 mm/min. This corresponded to calculated initial loading rates ranging between 0.4 and 1600 kN/s. The results of the tension tests clearly show that the rate-dependent behavior of fasteners in SFRC with 30 and 50 kg/m3 hooked-end-type fibers fits well to the previously reported rate-dependent concrete cone behavior in normal plain concrete. Additionally, a positive influence of the fibers on the concrete cone capacity is clearly visible.

scholarly journals Hydration of Calcium Sulfoaluminate-Based Binder Incorporating Red Mud and Silica Fume

2019 ◽  
Vol 9 (11) ◽  
pp. 2270 ◽  
Author(s):  
Yubin Jun ◽  
Jae Hong Kim ◽  
Taewan Kim
Keyword(s):  
Compressive Strength ◽  
Silica Fume ◽  
Red Mud ◽  
Drying Shrinkage ◽  
Pozzolanic Activity ◽  
Main Reaction ◽  
Main Reaction Product ◽  
Replacement Level ◽  
Calcium Sulfoaluminate ◽  
Expansive Agent

This study investigated the properties of hardened pastes made with calcium sulfoaluminate expansive agent (CSA), red mud, and silica fume. Five different ratios of 10:90, 20:80, 30:70, 40:60, and 50:50 were applied as the weight ratios of CSA and red mud. Red mud was replaced with 0, 5, and 10% silica fume by weight. Compressive strength, drying shrinkage, XRD, MIP, and SEM/EDS of the hardened pastes were performed. The results indicated that as the amount of CSA increased (i.e., as the amount of red mud decreased) up to 30%, sample strengths showed a tendency to increase. The main reaction product of the pastes was expansive ettringite, which was formed from the consumption of ye’elimite, anhydrite, gypsum, and Ca(OH)2. It was expected that C-S-H would be formed by the reaction of C2S in red mud; however, C-S-H phase was not present, and the pozzolanic activity due to the use of silica fume did not occur. The increase of CSA replacement level was effective for controlling the drying shrinkage of the samples. However, 50% replacement level of CSA induced excessive expansion, leading to the reduction in strength. It was found that the excessive expansion in the sample was reduced by the addition of silica fume.

scholarly journals Development of Eco-Friendly Cement Using a Calcium Sulfoaluminate Expansive Agent Blended with Slag and Silica Fume

2021 ◽  
Vol 11 (1) ◽  
pp. 394
Author(s):  
Taewan Kim ◽  
Ki-Young Seo ◽  
Choonghyun Kang ◽  
Tak-Kee Lee
Keyword(s):  
Silica Fume ◽  
Mechanical Performance ◽  
Hydration Product ◽  
Early Age ◽  
Low Carbon ◽  
Calcium Sulfoaluminate ◽  
Mixing Ratios ◽  
Expansive Agent ◽  
Binder Ratio

This is an experimental study on the development of a low-carbon, eco-friendly cement containing a calcium sulfoaluminate expansive agent (CSAe), slag, and silica fume (SF). The cement to be developed has a low water/binder ratio (w/b) of 0.5 and is designed to be used for structural purposes, with focus on its mechanical performance. CSAe, slag, and SF were mixed at various mixing ratios. The main hydration product of the slag-based CSAe cement in the experiment was ettringite. Substituting less than 30% of CSAe showed a sufficient level of mechanical performance; that is, the material could be used as structural cement. SF controlled the excessive expansion of CSAe. However, since the developed slag-CSAe-SF cement has low early age (1 d) strength, follow-up research is needed for improvement.

Effects of Expansive Agent and Steel Fiber on the Properties of the Fly Ash Ceramsite Lightweight Aggregate Concrete

2013 ◽  
Vol 357-360 ◽  
pp. 1332-1336 ◽  
Author(s):  
Shi Ping Cao ◽  
Qi Fan Zhou ◽  
Yi Liang Peng ◽  
Guo Xin Li
Keyword(s):  
Fly Ash ◽  
Bending Strength ◽  
Steel Fiber ◽  
Lightweight Aggregate ◽  
High Strength ◽  
Lightweight Aggregate Concrete ◽  
Enhancement Effect ◽  
Aggregate Concrete ◽  
Expansive Agent ◽  
Binder Ratio

Portland cement, silica fume, superplasticizer and fly ash cemamsite were used to obtain a high strength lightweight aggregate concrete with lower water to binder ratio. An enhancement effect on the strength was gained by adding steel fiber. When the expansive agent added with the steel fiber a synergistic reinforcing effect on the compressive strength, tensile strength and bending strength was obtained because of more energy consumed to pull the fibers out under the different loads.

Microstructure and Strength Characteristics Analysis of Shrinkage-Compensating Shotcrete

2011 ◽  
Vol 287-290 ◽  
pp. 1247-1251 ◽  
Author(s):  
Wei Huang ◽  
Qin Yong Ma
Keyword(s):  
Portland Cement ◽  
Steel Fiber ◽  
Concrete Strength ◽  
Strength Properties ◽  
Strength Characteristics ◽  
Micro Structure ◽  
Cement Slurry ◽  
Expansive Agent ◽  
Characteristics Analysis ◽  
Mineral Compositions

Due to the easy cracking of shotcrete, shrinkage-compensating shotcrete is researched and its micro-structure and strength properties are analyzed. Firstly, cement slurry is made by CSA, accelerating agent and two different cements. When hydrated 3 days and 28 days , hydration products of cement slurry are analyzed by SEM and XRD in feature, crystal characteristics and mineral compositions. The compatibility of the two different cements and admixtures is studied in apparent characteristics, and the fact that Portland cement is more suitable for making shrinkage-compensating shotcrete is obtained. Then, mechanical properties of concrete which consists of Portland cement, expansive agent and steel fiber are did to analyze the influence of strength characteristics caused by mix amount of expansive agent and steel fiber. The results show that the compression strength and tensile strength of concrete improve with the increasing mix of steel fiber. Incorporation of the expansive agent is greater impact on concrete strength, when mix amount of expansive agent is 8%, strength properties are the best. When mix amount of steel fiber is 1.0% and expansive agent is 8%, the effect of cooperative enhancement is the best.

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