Mechanical Properties and Durability of Polypropylene and Steel Fiber-Reinforced Recycled Aggregates Concrete (FRRAC): A Review

With the development of concrete engineering, a large amount of construction, demolition, excavation waste (CDEW) has been produced. The treated CDEW can be used as recycled aggregate to replace natural aggregate, which can not only reduce environmental pollution and construction-related resource waste caused by CDEW, but also save natural resources. However, the mechanical properties and durability of Recycled Aggregates Concrete (RAC) are generally worse than that of ordinary concrete. Various fiber or mineral materials are usually used in RAC to improve the mechanical properties and durability of the matrix. In RAC, polypropylene (PP) fiber and steel fiber (SF) are two kinds most commonly used fiber materials, which can enhance the strength and toughness of RAC and compensate the defects of RAC to some extent. In this paper, the literature on PP fiber- and SF-reinforced RAC (FRRAC) is reviewed, with a focus on the consistence, mechanical performance (compressive strength, tensile strength, stress–strain relationship, elastic modulus, and shear strength), durability (water absorption, chloride permeability, carbonation, freeze–thaw cycling, and shrinkage), and microstructure. The research findings regarding FRRAC were analyzed and compared. The results showed that adding mineral additives and fiber in RAC had a good synergistic effect, which made FRRAC have good mechanical properties, high durability and high temperature resistance, and several application prospects. The information and summary presented in this paper exhibit new knowledge and information on the application of FRRAC.

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MECHANICAL PROPERTIES OF RECYCLED AGGREGATE CONCRETE WITH STEEL FIBER: A REVIEW

Tikrit Journal of Engineering Sciences ◽

10.25130/tjes.26.3.05 ◽

2019 ◽

Vol 26 (3) ◽

pp. 37-42

Author(s):

Ashtar S. Al-Luhybi

Keyword(s):

Mechanical Properties ◽

Steel Fiber ◽

Recycled Aggregate Concrete ◽

Strength Characteristics ◽

Recycled Aggregate ◽

Recycled Aggregates ◽

Aggregate Concrete ◽

Building Process

In the building process, the recycling of aggregates arising from building and demolition debris is one of the best alternatives to maintain the environment and the areas needed to bury these debris. It also helps to preserve natural concrete sources from depletion efficiently. The use of recycled aggregates in new concrete manufacturing, however, leads to a decrease in concrete\\\’s strength characteristics. This reduction rises with the rise in the percentage of recycled aggregates used in concrete, which has caused many researchers to undertake many researches on how to enhance the characteristics of recycled aggregate-containing concrete. This paper presents several studies that examined the effect of adding steel fiber to improve the properties of concrete containing a coarse recycled aggregate.

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Preparation of Long Sisal Fiber-Reinforced Polylactic Acid Biocomposites with Highly Improved Mechanical Performance

Polymers ◽

10.3390/polym13071124 ◽

2021 ◽

Vol 13 (7) ◽

pp. 1124

Author(s):

Zhifang Liang ◽

Hongwu Wu ◽

Ruipu Liu ◽

Caiquan Wu

Keyword(s):

Mechanical Properties ◽

Polylactic Acid ◽

Mechanical Performance ◽

Tensile Elongation ◽

Sisal Fiber ◽

Fiber Reinforced ◽

Impact Performance ◽

The Matrix ◽

Blending Process ◽

Extension Direction

Green biodegradable plastics have come into focus as an alternative to restricted plastic products. In this paper, continuous long sisal fiber (SF)/polylactic acid (PLA) premixes were prepared by an extrusion-rolling blending process, and then unidirectional continuous long sisal fiber-reinforced PLA composites (LSFCs) were prepared by compression molding to explore the effect of long fiber on the mechanical properties of sisal fiber-reinforced composites. As a comparison, random short sisal fiber-reinforced PLA composites (SSFCs) were prepared by open milling and molding. The experimental results show that continuous long sisal fiber/PLA premixes could be successfully obtained from this pre-blending process. It was found that the presence of long sisal fibers could greatly improve the tensile strength of LSFC material along the fiber extension direction and slightly increase its tensile elongation. Continuous long fibers in LSFCs could greatly participate in supporting the load applied to the composite material. However, when comparing the mechanical properties of the two composite materials, the poor compatibility between the fiber and the matrix made fiber’s reinforcement effect not well reflected in SSFCs. Similarly, the flexural performance and impact performance of LSFCs had been improved considerably versus SSFCs.

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Discrete Element Simulation Analysis of Biaxial Mechanical Properties of Concrete with Large-Size Recycled Aggregate

Sustainability ◽

10.3390/su13137498 ◽

2021 ◽

Vol 13 (13) ◽

pp. 7498

Author(s):

Tan Li ◽

Jianzhuang Xiao

Keyword(s):

Mechanical Properties ◽

Stress State ◽

Strain Curve ◽

Confining Pressure ◽

Recycled Concrete ◽

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Recycled Aggregates ◽

Aggregate Model ◽

Large Size

Concrete made with large-size recycled aggregates is a new kind of recycled concrete, where the size of the recycled aggregate used is 25–80 mm, which is generally three times that of conventional aggregate. Thus, its composition and mechanical properties are different from that of conventional recycled concrete and can be applied in large-volume structures. In this study, recycled aggregate generated in two stages with randomly distributed gravels and mortar was used to replace the conventional recycled aggregate model, to observe the internal stress state and cracking of the large-size recycled aggregate. This paper also investigated the mechanical properties, such as the compressive strength, crack morphology, and stress–strain curve, of concrete with large-size recycled aggregates under different confining pressures and recycled aggregate incorporation ratios. Through this research, it was found that when compared with conventional concrete, under the confining pressure, the strength of large-size recycled aggregate concrete did not decrease significantly at the same stress state, moreover, the stiffness was increased. Confining pressure has a significant influence on the strength of large-size recycled aggregate cocrete.

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Effects of maximum particle size of coarse aggregates and steel fiber contents on the mechanical properties and impact resistance of recycled aggregate concrete

Advances in Structural Engineering ◽

10.1177/13694332211017998 ◽

2021 ◽

pp. 136943322110179

Author(s):

DongTao Xia ◽

ShaoJun Xie ◽

Min Fu ◽

Feng Zhu

Keyword(s):

Mechanical Properties ◽

Particle Size ◽

Steel Fiber ◽

Impact Resistance ◽

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Aggregate Concrete ◽

Coarse Aggregates ◽

Maximum Particle Size ◽

Maximum Particle

Fiber reinforced recycled aggregate concrete has become a new type of green concrete material. The maximum particle size of coarse aggregates and steel fiber contents affect the mechanical properties and impact resistance of recycled aggregate concrete. However, such studies are rare in literature. The present paper shortens the gap through experimental study. A total of 144 specimens of 12 kinds of concrete mixtures were tested, which adopted different steel fiber volume admixtures (0%, 0.8%, 1.0%, 1.2%) and recycled coarse aggregates in different maximum particle sizes (9.5, 19, 31.5 mm) replacing 30% natural coarse aggregate. The compressive strength, splitting tensile strength, and impact resistance of the 12 concrete mixtures were tested. The results showed that the compressive strength, splitting tensile strength, and impact resistance of recycled aggregate concrete increased first and then decreased with the increase of the maximum particle size. The recycled aggregate concrete with the maximum particle size of 19 mm had the highest mechanical properties and impact resistance. Besides, with the increase of steel fiber content, the compressive strength, splitting tensile strength, and impact resistance of recycled aggregate concrete showed an increasing trend. Considering a large amount of experimental data and the coupling effect of steel fiber contents and the maximum particle size of coarse aggregates, the Weibull distribution function was introduced to analyze the impact test results and predict the number of resistance to impact under different failure probabilities. The results showed that the number of blows of the recycled aggregate concrete followed a two-parameter Weibull distribution, and the estimated value of the number of resistance to impact for failure increased with the increase of the failure probability.

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Microstructural analysis of Al6063/sic with calcium additives for hardness enhancement

MATEC Web of Conferences ◽

10.1051/matecconf/201822503007 ◽

2018 ◽

Vol 225 ◽

pp. 03007

Author(s):

Balaji Bakthavatchalam ◽

Khairul Habib ◽

Namdev Patil ◽

Omar A Hussein

Keyword(s):

Mechanical Properties ◽

Silicon Carbide ◽

Matrix Material ◽

Microstructural Analysis ◽

Wear Loss ◽

Alloying Element ◽

Silicon Phase ◽

High Durability ◽

The Matrix ◽

Al6063 Alloy

Microstructural Analysis plays an important role in enhancing the mechanical properties of metals and composites. Usually Aluminium Silicon Carbide (Al6063/SiC) alloys are mixed with strontium, sodium and antimony for high durability even though they are toxic and costly. As an alternative calcium is used as an alloying element to improve the mechanical property of Al6063/Sic alloy. In this paper Al6063 is chosen as the matrix material while Sic is used as a reinforcement where calcium powder is added to modify the silicon phase of the composite. Finally, concentration of Silicon carbide is varied from 0 to 150 mg to produce four specimens of Al6063 alloy and it is subjected to microstructure analysis which showed the reduction of grain size and therefore improvement in the hardness from 52.9 HV to 58.4 HV and decrease in the wear loss from 3.97 to 3.27 percentage.

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Microstructure and Mechanical Performance of AZ31-1.7 Wt.% Si Alloy Processed by Cyclic Channel Die Compression

Materials Science Forum ◽

10.4028/www.scientific.net/msf.667-669.457 ◽

2010 ◽

Vol 667-669 ◽

pp. 457-461

Author(s):

Wei Guo ◽

Qu Dong Wang ◽

Man Ping Liu ◽

Tao Peng ◽

Xin Tao Liu ◽

...

Keyword(s):

Mechanical Properties ◽

Grain Size ◽

Tensile Strength ◽

Mechanical Performance ◽

Chinese Script ◽

Cast State ◽

Microstructure And Mechanical Properties ◽

Mean Grain Size ◽

The Matrix ◽

The Mean

Cyclic channel die compression (CCDC) of AZ31-1.7 wt.% Si alloy was performed up to 5 passes at 623 K in order to investigate the microstructure and mechanical properties of compressed alloys. The results show that multi-pass CCDC is very effective to refine the matrix grain and Mg2Si phases. After the alloy is processed for 5 passes, the mean grain size decreases from 300 μm of as-cast to 8 μm. Both dendritic and Chinese script type Mg2Si phases break into small polygonal pieces and distribute uniformly in the matrix. The tensile strength increases prominently from 118 MPa to 216 MPa, whereas the hardness of alloy deformed 5 passes only increase by 8.4% compared with as-cast state.

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Toughness of ECC Evaluated by Nominal Fracture Energy

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.238.57 ◽

2012 ◽

Vol 238 ◽

pp. 57-60 ◽

Cited By ~ 1

Author(s):

Shu Ling Gao ◽

Wei Shao ◽

Jin Li Qiao ◽

Ling Wang

Keyword(s):

Glass Fiber ◽

Fracture Energy ◽

Steel Fiber ◽

Volume Ratio ◽

Fiber Glass ◽

Fiber Volume ◽

High Durability ◽

The Matrix ◽

Pva Fiber ◽

Very High

ECC (Engineered Cementitious Composites) has ultra-high toughness and can be used in the zone needing the ultra-high tensile strain and very high durability. In order to investigate the toughness of ECC, the normal fracture energy GFis calculated and compared with ordinary concrete. The influence of the matrix (fly ash, silicon fume), the fiber (glass fiber, steel fiber and PVA fiber) and the fiber volume ratio on the GFof ECC are analyzed. The research indicates that silicon fume and glass fiber, steel fiber are all not able to be used in ECC. But flash ash and PVA fiber are very suit for using in ECC, the toughness of ECC increases with the increase of their content.

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Studies on Hemp and Recycled Aggregate Concrete

International Journal of Concrete Structures and Materials ◽

10.1186/s40069-020-00429-6 ◽

2020 ◽

Vol 14 (1) ◽

Author(s):

Samer Ghosn ◽

Nour Cherkawi ◽

Bilal Hamad

Keyword(s):

Mechanical Properties ◽

Fiber Length ◽

Plain Concrete ◽

Recycled Concrete ◽

Recycled Aggregate Concrete ◽

Recycled Aggregate ◽

Recycled Aggregates ◽

Silane Treatment ◽

Hemp Fiber ◽

Fiber Treatment

Abstract This paper reports on the first phase of a multi-phase research program conducted at the American University of Beirut (AUB) on “Hemp and Recycled Aggregates Concrete” (HRAC). HRAC is a new sustainable concrete material where hemp fibers are incorporated in the mix, the coarse aggregate content is reduced by 20% of the concrete volume, and 50% of the natural coarse aggregates (NCA) are replaced by recycled concrete aggregates (RCA), thus saving on natural resources and addressing the problem of waste material disposal. The effect of the new material on concrete consistency and hardened mechanical properties was studied. Also, few durability tests were conducted. Variables included percentage replacement of NCA by RCA (0 or 50%), maximum size aggregate (10 or 20 mm), hemp fiber length (20 or 30 mm), and hemp fiber treatment (alkali or silane or acetyl). Fiber characterization tests were conducted including morphology, crystallinity, and thermal analysis. The tests indicated that alkali and acetyl fiber treatments were better than the silane treatment in removing impurities on the fiber surface. Also, alkali and acetyl treatments have increased the crystallinity of the fibers while silane treatment decreased it. Results of mechanical properties tests showed that while HRAC has considerable lower compressive strength and modulus of elasticity than plain concrete, the flexural strength and splitting tensile strength are not significantly affected. The flexural stress–strain behavior of HRAC is ductile as compared to the brittle behavior of the plain concrete beams indicating positive impact on toughness and energy dissipation. The durability tests indicated that whereas HRAC mixes have higher absorption than plain concrete, they have better thermal properties and their resistance to freeze–thaw cycles is comparable to plain concrete. All test results were not significantly affected by fiber length or fiber treatment.

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Investigation of the mechanical properties of concrete containing recycled aggregate and scrap crumb rubber and polypropylene fibers

Progress in Rubber Plastics and Recycling Technology ◽

10.1177/1477760620977500 ◽

2020 ◽

pp. 147776062097750

Author(s):

Moein Khoshroo ◽

Ali Akbar Shirzadi Javid ◽

Nima Rajabi Bakhshandeh ◽

Mohamad Shalchiyan

Keyword(s):

Mechanical Properties ◽

Tensile Strength ◽

Compressive Strength ◽

Polypropylene Fiber ◽

Crumb Rubber ◽

Recycled Aggregate ◽

Recycled Aggregates ◽

Fine Aggregate ◽

Mixture Ratio ◽

Coarse Aggregates

In this study, the effect of using crumb rubber and recycled aggregates on the mechanical properties of concrete has been evaluated as areplacement of fine and coarse aggregates In order to add the admixtures and evaluate their combined effect, 20 different types of concrete mixture ratio were prepared. The results indicated that in those samples containing crumb rubber and recycled aggregates the compressive strength is reduced and adding fiber up to 0.1%. to these concrete samples can improve the compressive strength Also, the tensile strength of the samples mixed with crumb rubber and recycled aggregates were decreased, and with the addition of propylene fiber up to 0.4%. the tensile strength slightly increased Moreover by adding the crumb rubber to the samples the elasticity modulus was reduced but by adding fiber to samples about 0.1% and 0.2.% the modulus of elasticity of concrete in all samples were increased. According to the results, it can be said that using the combination of 5% of crumb rubber as a replacement of fine aggregate, and the combination of 35% of recycled aggregates as a replacement of coarse aggregate, and also by adding 0.1% polypropylene fiber in volumetric percentage of concrete along with adding 7% of micro silica as a replacement of cement led to the best effect on the mechanical properties of concrete.

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