Hybrid Fiber Reinforced Lightweight Concrete: Vegetal and Metalized Plastic Waste Fiber Synergy and Pull-Out Behavior

Wang B., Yan L., Kasal B.

In this study, the long-term pullout behavior and microstructure of the embedded coir fibers (a bundle of multi-monofilament fibers) from cementitious matrix were investigated. The experimental results were analyzed through statistical tests (i.e., Shapiro-Wilk test, Kolmogorov-Smirnov test, and Analysis of variance with Tukey’s honestly significant difference test) to address the reliability of the analyses and conclusions. The duration of fiber embedment in the matrix (i.e., 1, 2, 4, 8, 12, and 24 weeks), and the addition of fly ash (i.e., weight replacement ratio to cement for 0%, 10%, and 20%) were considered as the test parameters. The results show that the fibers with larger diameters tended to have tensile failure rather than pullout failure during the test. When the fibers had larger embedment length in the cementitious material, the pullout load–displacement curve changed from slip-hardening to slip-softening pattern. The highest fiber pullout strength was recorded when tested at 24-week. However, the highest fiber pullout energy was not recorded at 24-week but at 2-week. It can be concluded that with a longer embedment duration, the interfacial bond between fiber and matrix will increase but the coir fiber itself will be embrittled. This is due to the penetration of mortar into fiber surface along with a longer embedded duration, which was observed under scanning electron microscope. The pozzolanic reaction of fly ash did not improve the fiber–matrix interfacial bond strength. To the contrary, the pullout energy of the samples with 20% fly ash at week 1 was significantly lower than that with 10% fly ash or without fly ash. This was due to the unreacted spherical fly ash particles on the fibers surface that acted as lubricant during pullout.

Yimer T., Gebre A.

The mechanical behavior of fiber-cement composites is significantly influenced by the interfacial bonding between the fiber and the cement matrix. However, natural fibers are less chemically compatible with the cement matrix. As a result, it is essential to modify the surface of natural fibers to achieve good fiber-matrix interfacial bonds. In the current study, sisal fibers intended for use as a reinforcement in concrete matrices were alkali treated with NaOH solutions (2%, 5%, and 10%) for 12 hrs, 24 hrs, and 48 hrs. Water absorption, tensile strength, and surface morphological changes in fibers were studied. The effect of fiber treatment on the concrete was also assessed by measuring its slump, compressive strength, flexural strength, and toughness. Alkali treatment was discovered to reduce the water absorption capacity of sisal fiber. On the contrary, fiber surface morphology and mechanical properties improved up to a point and then gradually declined. The addition of treated sisal fiber considerably increases concrete’s flexural strength and toughness. However, an insignificant change in compressive strength was observed.

Ali B., Azab M., Kurda R., Kahla N.B., Atig M.

Nylon waste fibers similar to new nylon fibers possess high tensile strength and toughness; hence, they can be used as an eco-friendly discrete reinforcement in high-strength concrete. This study aimed to analyze the mechanical and permeability characteristics and life cycle impact of high-strength concrete with varying amounts of nylon waste fiber and micro-silica. The results proved that nylon waste fiber was highly beneficial to the tensile and flexural strength of concrete. The incorporation of a 1% volume of nylon waste fiber caused net improvements of 50% in the flexural strength of concrete. At the combined addition of 0.5% volume fraction of nylon fiber and 7.5% micro-silica, splitting tensile and flexural strength of high-strength concrete experienced net improvements of 49% and 55%, respectively. Nylon fiber-reinforced concrete exhibited a ductile response and high flexural toughness and residual strength compared to plain concrete. A low volume fraction of waste fibers was beneficial to the permeability resistance of high-strength concrete against water absorption and chloride permeability, while a high volume (1% by volume fraction) of fiber was harmful to the permeability-resistance of concrete. For the best mechanical performance of high-strength concrete, 0.5% nylon waste fiber can be used with 7.5% micro-silica. The use of micro-silica minimized the negative effect of the high volume of fibers on the permeability resistance of high-strength concrete. The addition of nylon waste fibers (at 0.25% and 0.5% volume) and micro-silica also reduced carbon emissions per unit strength of concrete.

Scarpitti N., Gavio N., Pol A., Sanei S.H.

The land disposal of waste material is a major environmental threat, and recycling efforts must be exponentially improved to mitigate it. In this paper, a feasibility study was conducted to reinforce concrete with waste materials that are not typically recycled. Compression testing was performed to evaluate the mechanical properties of the concrete specimens. The results were compared with a conventional wire mesh reinforcement used in concrete. Alternative reinforcements that are typically disposed of in landfill were used, namely, plastic regrind, carbon fiber scraps, tempered glass, coarse aggregates, and wire mesh. For each reinforcement type, four specimens were manufactured to evaluate the consistency of the results. Cylindrical specimens with ASME standard dimensions of 10.16 cm × 20.32 cm were tested using a Tinius-Olsen compression testing machine after seven days of curing. A constant strain rate of 0.25 MPa/s was applied until a load drop of 30% was detected. The results show that, while the recycled reinforcements had lower compressive strengths than the wire mesh, they maintained a load-carrying capacity of more than 80%. A major improvement was observed in terms of the ductility and toughness of the reinforced concretes. The recycled-carbon-fiber-reinforced specimens showed 12% strain at failure, a major improvement in concrete ductility. The findings of this research indicate that such recycled particles and fibers without any post-processing can be used in the reinforcement of concrete, with a significant improvement in ductility.

Said A., Elsayed M., El-Azim A.A., Althoey F., Tayeh B.A.

Shear failure of RC beams is one of the major problem in the construction industry today. It is desirable that the beam fails in flexure rather than in shear because the shear failure is catastrophic and occurs usually without advance warning. The aim of this paper is to evaluate the effectiveness of using ultra-high performance fiber reinforced concrete (UHPFRC) as a strengthening technique to improve the shear strength of RC beams. For this purpose, twelve RC beams were cast and tested under a four-point loading test up to failure. One beam was kept as a control beam without strengthening, and the other eleven beams were strengthened using different strengthening schemes. The main parameters considered in this experimental work were the thickness of the UHPFRC layer, the number of strengthening sides, the volume fraction of steel fibers, distribution length of UHPFRC layers (strengthening entire length, strengthening one-third of the length, strengthening using vertical and inclined strips), and strengthening schemes (casting or anchoring system). The experimental results revealed that UHPFRC is an effective technique in strengthening the RC beams in shear, as the behaviour of strengthened beams was improved in terms of ultimate shear strength up to 1.54 times, initial stiffness up to 2.75 times, ductility up to 3.37 times, and toughness up to 4.77 when compared to the un-strengthened beam. Furthermore, most of the strengthened beams failed in a ductile manner by forming flexural cracks in the maximum moment zone. In particular, the full casting of the UHPFRC strengthening scheme was more efficient than the UHPFRC laminates in improving the shear strength of tested beams. Roughening the beam surface improved the bond between the beam surface and the UHPFRC. Moreover, strengthening the beams by vertical or inclined strips had a substantial contribution in increasing shear capacity.

Safayenikoo H.

In a year, millions of forms of plastic are produced, and approximately, half of the generated plastics are used once only. Incorrect and insufficient management of these waste materials causes adverse effects on the nature of the soil, water, humans, and animals’ life. One type of waste plastic is metalized plastic waste (MPW), which is used mainly in different types of food packaging productions, and there is no appropriate technology for reusing it all over the world. In this paper, the effect of MPW as a fiber by 0.5% and 1% on compressive, flexural load capacity, and toughness of green concrete containing 7.5% and 15% silica fume or natural zeolite in Oman Sea tidal zone environment at 28, 90, and 180 days was investigated. The results indicate that by adding the MPW fiber, the compressive strength and maximum flexural load capacity of green concrete were decreased 25% and 15%, respectively. Meanwhile, the effect of MPW fiber on concrete containing 15% silica fume was greater than 7.5% silica fume concrete. Flexural toughness of natural zeolite concrete containing 0.5% MPW fiber was up to 510.9% greater than the observed one. Moreover, the toughness of green concrete containing 1% MPW fiber and zeolite was up to 35% greater than 0.5% MPW concrete. Meanwhile, the effect of MPW fiber on flexural toughness of concrete containing 15% natural zeolite was greater than 7.5% natural zeolite concrete.

Nguyen D., Thai D., Lam M.N.

Wang B., Yan L., Kasal B.

This paper provides a comprehensive review on the research of coir fibre and coir fibre reinforced cementitious composite (CFRC) in the past 20 years. In the first part, the extraction process, morphology, density, chemical composition, and tensile performance of coir fibres are discussed. Then, the pull-out performance, physical properties (i.e., density, thermal and acoustic insulation), short- and long-term properties (i.e., compressive, flexural, impact, and dynamic performance) of CFRC are reviewed. Existing modification methods (i.e., cementitious matrix and fibre surface modifications) to improve the bond and mechanical behaviour of CFRC and the practical application of CFRC in construction are presented. Future perspectives of CFRC studies are highlighted, including the validation of existing models (i.e., for the prediction of coir tensile strength as well as bond strength and total energy of CFRC), further investigations on long-term, seismic, fire performance of CFRC, and the use of coir fibre in geopolymer and coconut shell aggregate concrete towards practical application.

Momoh E.O., Osofero A.I., Menshykov O.

The use of leaflet ribs from oil palm trees - Oil Palm Broom Fibres (OPBF) in reinforcingcement composites have shown some prospects according to recent studies. However, only little isunderstood regarding their bond interaction with cement matrices. Samples were prepared toinvestigate the pull-out response of OPBF in both single and combined form from concrete. For thecombined fibres, single OPBF strands were wound around one another longitudinally (in helical form)to form tendons. A comparison was made between the maximum bond strengths of untreated andtreated OPBF in concrete. The OPBF were pre-treated by soaking in sodium hydroxide andtriethylvinylsilane solutions to improve their bond strength with concrete. The reported treatmentscould improve the potential of OPBF tendons as reinforcement in lightly loaded concrete beamsultimately resulting in an environmentally friendly and affordable construction.

Bamaga S.O.

Abstract This paper presents the results of a study conducted to investigate the effects of incorporating Sefri Date Palm Leave Fibers (SDPLF) into the mortar. A total of seven mixtures were prepared and tested. SDPLF were collected from local farms. The fibers were then cleaned, dried, and cut to different sizes of 10 mm, 20 mm, and 50 mm, maintaining the same individual fiber width of approximately 5 ± 2 mm. The content of SDPLF in mortars was kept to 1% and 3% by mass. The physical and mechanical properties of SDPLF fibers and SDPLF mortars were investigated. The compressive strength at 7, 14, and 28 days was determined. The water absorption rate test was carried out on mortars containing 1% SDPLF fibers. The results showed that mortars with SDPLF have lower workability, lower density, and lower compressive strength as compared to control mortars. However, they are still acceptable for use in construction works. Mortars containing 10 mm and 20 mm SDPLF fibers by mass showed significant improvement in terms of water absorption rate as compared to the control mortar.

Marvila M.T., Rocha H.A., de Azevedo A.R., Colorado H.A., Zapata J.F., Vieira C.M.

The application of vegetable fibers has gained great notoriety as a building material, due to its availability, mechanical properties and low cost. In this sense, the objective of this work is to carry out a bibliographic review on the application of this fibers in cementitious matrices, including concrete and mortar. This work analyzes the main characteristics of natural vegetable fibers that affect the properties of composites, such as geometric, physical, mechanical and chemical properties. The characteristics of the alkaline treatments carried out on the fibers are highlighted to improve the adhesion properties, durability, water absorption and tensile strength. Some case studies were analyzed in detail: coconut, bamboo and bananas fibers, all in combination with cementitious matrices. Finally, some suggestions for future work are highlighted, showing the need for further studies on the application of natural fibers in cementitious composites.

Channa I.A., Saand A.

The main objective of this research work is to investigate the influence of the addition of waste materials, like aluminium waste material, Soft Drink Tin Fibers (SDTF) or soft tins to improve mechanical properties of concrete and also study the strength behavior of concrete, such as flexural strength and indirect or split tensile strength. It has been acknowledged that the use of fibers in concrete has considerable effects to improve strength parameters and characteristics of concrete. In this research work, similar efforts are made to present the effects of soft tin fibers or aluminium waste material as a reinforcing material in concrete and to assess the mechanical behavior of concrete. Particularly, this research work aimed to investigate experimentally the effect of soft drink tins on tensile (cylinder splitting tensile strength) and flexural strength. Soft tin fibers of 25.4  5  0.5 mm in size were used and added from 1 to 5% by the weight of cement with the design mix of 1:1.624:2.760 at 0.50 w/c ratio. Therefore, 6 batches (every batch contained 3 prisms and 3 cylinders) were prepared and cast for evaluation of tensile and flexural strength. One batch was cast without inclusion of fibers (controlled batch) and remaining 5 batches were cast with the addition of fibers using 1, 2, 3, 4, and 5% respectively. It was revealed from obtained results that split tensile strength and flexural strength of specimen increases as compared to controlled batch up to 4% addition of fibers. Moreover, beyond 4% soft drink tin fiber level, strength begins to fall down. Thus, it can be suggested that mechanical properties of concrete can be enhanced by 4% of soft drink tin fibers. Moreover, in this study, soft drink tin fibers (SDTF) or aluminium waste are used as the application of utilization of waste materials as a partial construction material and also on another side it controls the solid waste and environmental pollution. Doi: 10.28991/cej-2021-03091718 Full Text: PDF

Ajouguim S., Page J., Djelal C., Waqif M., Saâdi L.

• Alfa fibers do not significantly influence the fresh mortar properties. • The addition of 1%vol of Alfa fibers improve the mortar flexural strength. • The addition of Alfa fibers leads to a modification on cement hydration kinetics. • The addition of Alfa fibers increase the water accessible porosity of the composite. The Alfa plant is indigenous and spans a large zone throughout North Africa. Recently, Alfa plant has been used in building materials, notably as a reinforcement. This study aims to valorize the Alfa plant into fiber-reinforced mortar based on a cement-glass composite mix design. Two Alfa fiber morphologies are considered herein: different cutting lengths (10, 20 and 30 mm), and ground using a knife mill (shorter than 2 mm). These fibers were added to mortars at various volume ratios: 1, 2 and 3%. The workability and density of these distinct formulations were then measured in their fresh state. In comparison with the control mortar (CM), the introduction of Alfa fibers (either cut or ground), with ratios below 2% vol., leads to a slight decrease in mixture workability. However, Alfa fibers do not significantly alter the fresh material density. It was recorded a delay in setting time of the composites as a function of fiber addition rate. In the hardened state, an improvement in flexural strength is noticed for mortars reinforced with 1% vol. of fibers compared to the CM. However, results show that the increase in either type of fiber (cut or ground) generates a decrease in compressive strength compared to the CM. This outcome can be confirmed by both the decrease in heat released during the hydration reaction and water-accessible porosity inside the matrix.

Jain A., Sharma N., Choudhary R., Gupta R., Chaudhary S.

• Sustainable concrete was produced using non-metalized waste plastic bag fibers (NMWPF) and fly ash (FA). • The addition of NMWPF in concrete augmented tensile strength, and resistance to impact and drying shrinkage. • The resistance to water-based durability characteristics enhanced on addition of NMWPF along with FA. • Statistical analysis showed that most of concrete characteristics were predominantly affected by NMWPF. The continuous production and dumping of plastic waste cause a serious impact on environmental pollution. Deploying of plastic waste in construction products reduces environmental pollution and also minimizes construction and dumping cost. This paper examines the mechanical, durability and impact attributes of concrete prepared with non-metalized waste plastic bag fibers (NMWPF) and fly ash (FA). Ten mixtures were designed in which five mixtures were Ordinary Portland cement (OPC) based including NMWPF content of 0, 0.50, 0.75, 1.00, and 1.25%. Remaining mixtures were FA blended mixes having same percentage of NMWPF content as that of OPC based mixtures, wherein 20% of cement was swapped with FA. The addition of NMWPF together with FA in concrete reduced the requirement of superplasticizer dosage. The compressive strength of both OPC and FA-based concrete reduced by the addition of NMWPF at all curing ages. However, FA-based concrete (prepared with and without NMWPF) exhibited better compressive strength than OPC based concrete at 90 days curing. The addition of NMWPF together with FA in concrete significantly augmented flexural strength, split tensile strength and resistance to abrasion, impact and drying shrinkage. Though resistance to water penetration decreased on the addition of NMWPF in both OPC and FA-based concrete, the FA-based concrete (prepared with and without NMWPF) performed better than OPC based concrete. Moreover, statistical analysis showed that most of concrete characteristics were predominantly affected by NMWPF. Overall, this research revealed positive results on using NMWPF along with FA in concrete and paved the way for further researches in same field.

Awolusi T.F., Falana J.N., Ajayi P.O., Akinkurolere O.O., Aluko O.G.

AbstractThe hybridization of two different elements is done for synergy and better performance. This study investigates the effects of combining bamboo, steel, and carpet fibers, as reinforcement in concrete. The steel and carpet fibers were obtained from discarded tires, and carpets, respectively. The addition of fibers to the mixes was kept constant at 2% of the concrete volume. The first category concrete mix contained a hybrid of steel and carpet fibers at a fraction of 1.75% and 0.25%, respectively, the second category combined steel and bamboo fibers at a fraction of 1% - 1%. The third category contained only steel fibers at a 2% volumetric fraction. The mechanical property of the concrete was evaluated through compressive and flexural strengths, while the durability was examined through water absorption and the acid attack. The compressive strength results obtained for the three categories of fiber reinforced concrete ranged between 7.2 and 12.8 N/mm2, with the third category performing better. Also, the flexural strength results ranged between 5.37 and 7.47 N/mm2, with the first category having the best results. The second category had the least water absorption capacity, and the concrete reinforced with only steel fibers showed the best acid attack resistance. The results also confirmed that short discontinuous fibers are suitable strength and durability enhancers in producing durable eco-friendly concrete.