scholarly journals Study on Mix Proportion Optimization of Manufactured Sand RPC and Design Method of Steel Fiber Content under Different Curing Methods

Materials ◽  
2019 ◽  
Vol 12 (11) ◽  
pp. 1845 ◽  
Author(s):  
Chunling Zhong ◽  
Mo Liu ◽  
Yunlong Zhang ◽  
Jing Wang
Keyword(s):  
Steel Fiber ◽  
Design Method ◽  
Fiber Content ◽  
Orthogonal Experimental Design ◽  
Curing Conditions ◽  
Practical Applications ◽  
Manufactured Sand ◽  
Binder Ratio ◽  
Curing Methods ◽  
Reactive Powder

This study investigated four factors (water/binder ratio, silica fume, fly ash, and sand/binder ratio) using the orthogonal experimental design method to prepare the mix proportions of a manufactured sand reactive powder concrete (RPC) matrix to determine the optimal matrix mix proportions. On this basis, we assessed the compressive and splitting tensile strengths of different steel fiber contents under natural, standard, and compound curing conditions to develop an economical and reasonable RPC for various engineering requirements. A calculation method for the RPC strength of the steel fiber contents was evaluated. The results showed that the optimum steel fiber content for manufactured sand RPC is 4% under natural, standard, and compound curing conditions. Compared with standard curing, compound curing can improve the early strength of manufactured sand RPC but only has a small effect on the enhancement of late strength. Although the strength of natural curing is slightly lower than that of standard curing, it basically meets project requirements and is beneficial for practical applications. The calculation formula of 28-day compressive and splitting tensile strengths of manufactured sand RPC steel fiber at 0%–4% is proposed to meet the different engineering requirements and the flexible selection of steel fiber content.

scholarly journals Reactive Powder Concrete Mix Ratio and Steel Fiber Content Optimization under Different Curing Conditions

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3615 ◽  
Author(s):  
Yunlong Zhang ◽  
Bin Wu ◽  
Jing Wang ◽  
Mo Liu ◽  
Xu Zhang
Keyword(s):  
Tensile Strength ◽  
Steel Fiber ◽  
Orthogonal Experiment ◽  
Fiber Content ◽  
Reactive Powder Concrete ◽  
Mixture Ratio ◽  
Curing Conditions ◽  
Compressive Performance ◽  
Binder Ratio ◽  
Reactive Powder

In this paper, a practical reactive powder concrete mixture ratio is created on the basis of an orthogonal experiment. Previous studies have combined the compressive and splitting tensile strengths of four categories of reactive powder concrete (RPC) for major materials. These categories include water/binder ratio, silica fume volume content, sand/binder ratio, and dosage of fly ash volume. The optimal mixing proportion of each factor was determined by analyzing the compressive strength of the RPC matrix. For this purpose, steel fiber was used as a reinforcing agent. The compressive and splitting tensile strength test results of steel fiber RPC were analyzed by comparing compound, standard, and natural curing. This was conducted to explore the improvement effect of different steel fiber contents on compressive performance, especially tensile strength of the RPC matrix. According to the results, the optimal steel fiber content was found to be 4% under the three curing conditions. The effect of compound curing on early strength was found to be greater in RPC than by natural or standard curing. However, the effect of late improvement is not obvious. Although standard curing is slightly stronger than natural curing, the performance under the latter can still meet engineering requirements.

scholarly journals Mechanical Properties of Carbon-Fiber RPC and Design Method of Carbon-Fiber Content under Different Curing Systems

Materials ◽  
2019 ◽  
Vol 12 (22) ◽  
pp. 3759 ◽  
Author(s):  
Xuejian Zhang ◽  
Lincai Ge ◽  
Yunlong Zhang ◽  
Jing Wang
Keyword(s):  
Carbon Fiber ◽  
Design Method ◽  
Fiber Content ◽  
Practical Application ◽  
X Ray Diffraction ◽  
Curing Conditions ◽  
Influencing Mechanism ◽  
Reactive Powder ◽  
Curing Compound ◽  
Curing Systems

Natural, standard, and compound curing are adopted to study the effect of different curing systems on the reinforcement of carbon fiber in reactive powder concrete (RPC). This work systematically studies the changes in RPC compressive and tensile strengths under different curing systems. Taking age, fiber content, and curing system as parameters, Scanning electron microscope (SEM) and X-ray diffraction (XRD) microscopic methods are used to study the influencing mechanism of carbon-fiber content and curing systems on RPC. The calculation methods of the RPC strength of different carbon-fiber contents are studied. Results show that the optimum carbon-fiber content of carbon-fiber RPC is 0.75% under the natural, standard, and compound curing conditions. In comparison with standard curing, compound curing can improve the early strength of carbon-fiber RPC and slightly affect the improvement of late strength. The strength is slightly lower in natural curing than in standard curing, but the former basically meets the requirements of the project and is beneficial for the practical application of this project. The calculation formula of 28-day compressive and splitting tensile strengths of carbon-fiber content from 0% to 0.75% is proposed to select the carbon-fiber content flexibly to satisfy different engineering requirements.

scholarly journals Effect of Hybrid Steel-Basalt Fiber on Behaviors of Manufactured Sand RPC and Fiber Content Optimization Using Center Composite Design

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Yunlong Zhang ◽  
Jiahui Liu ◽  
Jing Wang ◽  
Bin Wu
Keyword(s):  
Compressive Strength ◽  
Flexural Strength ◽  
Response Surface ◽  
Basalt Fiber ◽  
Fiber Content ◽  
Surface Model ◽  
Basalt Fibers ◽  
Curing Conditions ◽  
Manufactured Sand ◽  
Reactive Powder

The mechanical properties and workability of manufactured sand reactive powder concrete (RPC) mixed with steel and basalt fibers were studied using the response surface method. The central composite design was used to explore the 7-day and 28-day compressive strength, flexural strength, and workability of different amounts of mixed fiber-manufactured sand RPC. Results showed that when the steel fiber content was less than 2.5%, mixing basalt fibers can significantly improve the flexural strength and flexural-compressive ratio of RPC. The relationship equations of the two fibers with the 28-day compressive strength, flexural strength, and flexural-compressive ratio of the manufactured sand RPC were obtained through the response surface model. The model proved to be reliable according to the analysis of variance. The content of the two fibers was optimized by multiobjective optimization technology, and the optimal content of the mixed fiber-manufactured sand RPC under standard curing conditions was verified.

scholarly journals A Study on Optimum Mixture Ratio of Reactive Powder Concrete

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Mingyang Chen ◽  
Wenzhong Zheng
Keyword(s):  
Compressive Strength ◽  
Steel Fiber ◽  
Raw Materials ◽  
Reactive Powder Concrete ◽  
Mixture Ratio ◽  
Curing Methods ◽  
Main Components ◽  
Cement Strength ◽  
Reactive Powder ◽  
Design Factors

To optimize the main components of reactive powder concrete (RPC) for various curing methods, based on the fluidity and compressive strength, an inclusive experimental research is conducted on 58 different mixture ratios. The results indicate that owing to the increase of the cement strength, the RPC fluidity decreases and the cement strength is not proportional to the compressive strength. The addition of the fly ash and the nano-microbead is an effective way to improve the fluidity, and it is required at the low W/B ratio. However, the influence of the SF grade on the strength and fluidity is almost negligible. By considering the fluidity, strength, and economy of RPC as crucial design factors, SF90 is suggested. The contribution of the steel fiber to the compressive strength cannot be ignored. The upper envelope value of the steel fibers is required for the structure to resist appropriately against the fire. According to the test results, the mixture ratio formula is proposed through considering the characters of different compositions and curing methods. The strength coefficient k1 is introduced to verify the influence of the steel fiber content, and the parameters fb, αa, and αb in the formula are reevaluated. A reasonably good agreement between the calculated strength and those obtained from the tests is reported, except for the case of W/B = 0.16 with P.O.52.5 cement. The basic steps for preparations of different RPC strengths are given, which provide a valuable reference to choose appropriate raw materials and mixture ratio design for different strength values.

Tensile Properties of Steel Fiber-Reinforced Reactive Powder Concrete after High Temperature

2011 ◽  
Vol 413 ◽  
pp. 270-276 ◽  
Author(s):  
Wen Zhong Zheng ◽  
Hai Yan Li ◽  
Ying Wang ◽  
Heng Yan Xie
Keyword(s):  
Tensile Strength ◽  
High Temperature ◽  
Steel Fiber ◽  
Heating Temperature ◽  
Fiber Content ◽  
Reactive Powder Concrete ◽  
Fiber Reinforced ◽  
Critical Temperatures ◽  
Reactive Powder ◽  
The Relationship

87 prismatic flexural steel fiber-reinforced reactive powder concrete (RPC) specimens with the size of 40mm×40mm×160mm were tested as well as 87 dumbbell-shaped axis tensile RPC specimens after being exposed to different high temperatures. The effect of steel fiber content and heating temperature on the flexural and tensile strength of steel fiber-reinforced RPC was analyzed. With the steel fiber content increasing, the flexural and tensile strength of steel fiber-reinforced RPC after high temperature improve significantly, and they increase first and then decrease with the heating temperature elevated, and the critical temperatures are 200¡æ and 120¡æ, respectively. Equations are established to express the relationship between the flexural and tensile strength of steel fiber-reinforced RPC and the heating temperature. The theoretical curves are in good agreement with the test data.

scholarly journals Parametric studies on the workability and compressive strength properties of geopolymer concrete

2018 ◽  
Vol 27 (3-4) ◽  
Author(s):  
S. Nagajothi ◽  
S. Elavenil
Keyword(s):  
Compressive Strength ◽  
Setting Time ◽  
Experimental Studies ◽  
Strength Properties ◽  
Geopolymer Concrete ◽  
Low Carbon ◽  
Natural Sand ◽  
Curing Conditions ◽  
Manufactured Sand ◽  
Binder Ratio

AbstractGeopolymer concrete is a booming technology in the construction industry. Much research is occurring in geopolymer concrete, as it emits low carbon dioxide into the atmosphere, is eco-friendly material and is an alternative for cement. This research mainly focuses on the use of fly ash based geopolymer concrete in ambient curing conditions and the use of manufactured sand due to the scarcity of natural sand. Mainly studies have evolved on the workability, setting time and compressive strength by the effect of ground granulated blast furnace slag (GGBFS), manufactured sand (M-sand), alkaline activator solutions to binder ratio and the proportions of sodium silicate to sodium hydroxide (SS/SH) in geopolymer concrete and mortar. The experimental studies were carried out using nine geopolymer concrete mixes and the comparisons were made. The workability of concrete decreases by increasing the percentage of GGBFS, M-sand and the proportions of SS/SH whereas workability of concrete increases when increasing the alkaline liquid to binder ratio. The compressive strength of geopolymer mortar and concrete increases when the percentage of GGBFS and M-sand is increased, and it decreases by increasing the alkaline liquid content. There is no change in strength by decreasing the proportions of SS/SH.

Effect of fiber content on mechanical performance and cracking characteristics of ultra-high-performance seawater sea-sand concrete (UHP-SSC)

2020 ◽  
pp. 136943322097245
Author(s):  
Bo-Tao Huang ◽  
Yu-Tian Wang ◽  
Jia-Qi Wu ◽  
Jing Yu ◽  
Jian-Guo Dai ◽  
...  
Keyword(s):  
Crack Width ◽  
High Performance ◽  
Mechanical Performance ◽  
Fiber Content ◽  
Cumulative Probability ◽  
Practical Applications ◽  
Manufactured Sand ◽  
Future Design ◽  
Sea Sand ◽  
Cracking Characteristics

Developing seawater sea-sand concrete can address the challenges arising from the lack of freshwater and river/manufactured sand for making concrete on-site for sustainable marine and coastal construction. To eliminate the corrosion risk of steel fibers while maintaining the high ductility of concrete, this study aims to develop a new type of ultra-high-performance seawater sea-sand concrete (UHP-SSC) by using ultra-high-molecular-weight polyethylene fibers. The effect of fiber content (0%, 0.5%, 1.0%, and 1.5% by volume) on the mechanical performance and cracking characteristics of UHP-SSC was experimentally investigated. The results showed that as the fiber content increases, the tensile strength and strain capacity of UHP-SSC significantly increase, while the compressive strength slightly decreases (but still over 130 MPa). The stochastic nature of the crack width was characterized by the Weibull distribution. A probabilistic model was used to model the evolution of the crack width for UHP-SSC at different strain levels. The model showed good agreement with the experimental results, and it can be used to estimate the allowed tensile strain of UHP-SSC in practical applications for a given limit of crack width and cumulative probability. The findings in this study provide insights into the future design of UHP-SSC in marine and coastal applications.

Study of RPC Mechanical Properties and Anti-Freeze-Thaw Resistance

2010 ◽  
Vol 168-170 ◽  
pp. 1742-1748
Author(s):  
Yan Zhong Ju ◽  
Feng Wang ◽  
De Hong Wang
Keyword(s):  
Mechanical Properties ◽  
Silica Fume ◽  
Steel Fiber ◽  
Fiber Content ◽  
Reactive Powder Concrete ◽  
Cement Ratio ◽  
Water Cement Ratio ◽  
Freeze Thaw ◽  
Early Strength ◽  
Reactive Powder

To study the mechanical properties of RPC performance and freeze-thaw resistance，through the experimental study discussed the water-cement ratio, silica fume cement ratio, steel fiber content, curing system and other factors on the mechanical properties of reactive powder concrete and anti-freezing properties. Research indicates that many factors in the RPC, the water cement ratio is the most important factor, followed by the silica fume cement ratio, finally the steel fiber content, and curing system for the growth of its early strength also have a greater role.

scholarly journals Effect of Curing Conditions on the Compressive Strength of Self Compacting Concrete Incorporating Slag and Steel Fibres

2019 ◽  
Vol 8 (4) ◽  
pp. 4754-4760
Keyword(s):  
Compressive Strength ◽  
Treatment Period ◽  
Water Immersion ◽  
Site Conditions ◽  
Self Compacting Concrete ◽  
Steam Curing ◽  
Curing Conditions ◽  
Manufactured Sand ◽  
Curing Methods ◽  
Curing Cycle

The influence of different curing conditions on the compressive strength of Self compacting concrete in combination of Slag and Manufactured sand (MSand) is only little known, especially when subjected to steam accelerated curing process.Water immersion curing, Sealed curing, Curing compounds, Air Curing, Curing at site conditions and curing with steam were considered for the present study on the compressive strength of Self compacting concrete (SCC).The specimens were tested for 3,7,28&90 days. Out of the various curing methods, the highest compressive strength achieved is for Water immersion curing followed by Sealed curing (95%), curing compounds (93%), curing at site conditions (89%) and air curing (75%).Curing using steam was introduced to optimize the steam curing cycle for SCC. 36 different steam curing cycles were considered with varying temperatures of 50, 60 and 700C.The treatment period considered for the study were 8, 10, 12 &14 hours. From the experimental investigation, it is observed that increase in temperature and total cycle time led to higher immediate compressive strength. Out of the 36 curing cycles, the optimum cycle is having a temperature of 600 c, delay period of 5 hours and a treatment period of 12 hrs

scholarly journals Mix Proportion Design of Self-Compacting SFRC with Manufactured Sand Based on the Steel Fiber Aggregate Skeleton Packing Test

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2833
Author(s):  
Xinxin Ding ◽  
Minglei Zhao ◽  
Jie Li ◽  
Pengran Shang ◽  
Changyong Li
Keyword(s):  
Steel Fiber ◽  
Design Method ◽  
Fiber Reinforced Concrete ◽  
Steel Fibers ◽  
The Self ◽  
Void Content ◽  
Steel Fiber Reinforced Concrete ◽  
Complete Replacement ◽  
Manufactured Sand ◽  
Mix Proportion

A scientific and concise mix design method is an impending problem in the engineering application of self-compacting steel-fiber-reinforced concrete (SFRC). This paper focuses on the mix proportion of self-compacting SFRC, which is influenced by the steel fibers, along with its effects on the packing properties of the steel fiber aggregate skeleton. In total, 252 groups of packing tests were carried out for several main factors, including with various maximum particle sizes for the coarse aggregates, manufactured sand ratios ranging from 50% to 62%, and with different types of hooked-end steel fibers and crimped steel fibers, with volume fractions ranging from 0% to 2.0%. The results indicated that the void content and rational sand ratio of the steel fiber aggregate skeleton increased linearly with the fiber factor. These results provided a basis for the calculation of the binder content and rational sand ratio of the self-compacting SFRC. Combined with the absolute volume design method and the calculation formula for the water-to-binder ratio, a systematical procedure was proposed for the mix proportion design of the self-compacting SFRC. Based on the design method, eight groups of mixtures were cast and tested to verify the adaptability and practicability of the workability, air content, density, cubic compressive strength, and splitting tensile strength of the self-compacting SFRC. Meanwhile, the outcomes of this study confirmed the applicability of using manufactured sand as a complete replacement for natural sand for the self-compacting SFRC.

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