Structural behavior of reinforced lightweight self‐compacting concrete beams using expanded polystyrene as coarse aggregate and containing polyethylene terephthalate fibers

Through this study, an attempt was made to produce concrete beams from self‐compacting concrete (SCC) contain expanded polystyrene (EPS) beads as coarse aggregate and waste plastic fibers (WPFs) produced from cutting disposed packing straps in site. The beams were designed according to ACI‐318‐14, where three different reinforcement ratios were chosen for the purpose of checking the conductance of thresholds made of this type of environmentally friendly concrete under bending loads. The use of EPS with WPFs had a significant positive effect in reducing the density of concrete, and the highest percentage of reduction was equal to (38.46%). Using WPFs had a positive effect in increasing the flexural toughness of concrete prisms, and the maximum increment was equal to (180%) compared with these made from the reference mix. The results proved the possibility of producing lightweight concrete from the use of EPS waste and WPFs, three of which are structurally can be classified as lightweight concrete combination of normal weight and lightweight aggregates according to specifications requirements of ASTM330/330M‐14. Reinforced lightweight SCC beams behaved under flexural loads similar to the reinforced concrete beams made from normal weight concrete counterparts under flexural loads.


compacting lightweight concrete
Concrete is the main production for recycling waste materials and cleaning the climate.The utilization of self-consolidating lightweight concrete (SCLWC) can achieve two important advantages of the structure selfweight reduction and improving workability. 1 The SCLWC is highly suitable for the construction of structures that require less compressive strength (CS) than normal weight concrete but still need a low weight, that is, decrease the weight of construction. 2For instance, these are elements that are prefabricated and require transportation, structures, and elements where the concrete surface is exposed.It is suitable for use in renovation projects where additional loads are not desired. 3he use of self-compacting concrete (SCC) can also provide an important contribution to more sustainable development, that is, through the incorporation of large quantities of by-products from other industries (such as metal additives), the possibility of incorporating recycled materials into their composition in the replacement of natural aggregates and the potential increase in the susceptibility of structures that will lead to longer life cycles with the consequent reduction in global costs of structures and materials associated with demolition.SCLWC was first applied to a structure in Japan in 1992 when it was used to "construct a cable-stayed bridge's main girder."Over the last few years, SCLWC has found a number of applications, such as in precast stadium benches 4 and pre-stressed beams with spans reaching up to 20 m. 5 Currently, expanded polystyrene (EPS) light weight concrete is used in various structures, such as cladding panels, curtain walls, composite flooring systems, loadbearing concrete blocks, sub-base materials for use in pavement, floating marine structures, and protective layers of structures used for impact resistance, due to its good energy absorbing characteristics. 6hen necessary, the strength of LWC can be improved by combining coarse light weight aggregate LWA with fine stone aggregates.However, the maximum CS can be achieved in concrete with aggregates from waste clay, slag, and natural crushed stone aggregates.Spent clay aggregates are more beneficial in the grain shape as it enhances the mixtures' rheological attributes and CS. 7 The use of SCLWC also reduces the construction cost as it reduces the total dead load of the structural components and requires little, or no maintenance compared to similar steel structures. 8Lightweight self-consolidating concrete (LWSCC) can also improve the durability and strength of structures while offering better workability. 32 | Lightweight concrete containing expanded polystyrene beads (EPS-LWC) EPS-LWC has been commonly used in different applications since its invention 60 years ago.However, studies are yet to focus on the effect of new admixtures on the improvement of the strength and performance of EPS-LWC.9 There are three major steps during the production of EPS; these are the pre-expansion, aging, and molding stages.The pre-expansion stage involves the subjection of the small expandable beads to steam to cause softening of the thermoplastic polystyrene.The increase in vapor pressure due to the blowing agent causes the expansion of the beads to about 40 times their initial volume.The final density of the EPS block is determined at the prefoam stage.10,11 "After the preexpansion stage, the pre-foam is transferred to large silos via a fluidized drying bed for the ageing process, which is designed to allow air replacement of the expanding agent in the cells of the bead.The ageing process also encourages the cooling and stabilization of the pre-foam".11 After conditioning by aging, the next stage is to blow the pre-foam into a mold for further steaming and subsequent fusing of the expanded beads into a block.10,11 The chemical and mechanical attributes of the EPS are based on the AS-1366. Furthermore, ASTM-C578 (2019) 13 has provided additional specifications regarding the physical properties of EPS beads.12 EPS-LWC is typically used for nonstructural purposes; however, it has found use in loadbearing structural components where it exhibits high efficiency.13 Expanded polystyrene concrete is a new lightweight building material that exhibits good mechanical properties and a priori mechanical features that are suitable for the construction industry.Liu et al 6 study the mechanical properties of EPS concrete and relate these properties to the concrete matrix and particle size of EPS.In this paper, the CS, tensile strength, and flexural strength (FS) of EPS concrete with different sizes of EPS particles were compared.Based on the results of the CS tests, a CS expression was proposed.Ultrasonic testing was performed during the process of loading up to uniaxial compressive failure.6

| Lightweight concrete containing plastics
The variety of fibers that are available to add to the concrete mix is vast.There are many different categories of fibers, such as naturally occurring, synthetics, glass, and steel.Some popular types of synthetic fibers include polyethylene, polyester, and polypropylene. 14Currently, society is trying to become more sustainable to increase the longevity and availability of natural-occurring materials. 15To aid in this sustainability and protect the environment, researchers have started to test the effects of using recycled fibers such as waste pet bottles, plastic, glass, and old tires in concrete mixes.By using these types of fibers, the concrete mix would be more economical, and less waste would be produced. 16,17Each type of fiber has its own unique properties and characteristics, and they come in various sizes and compositions.The goal of using fibers in concrete is to improve various concrete properties while attempting to reduce the use of structural reinforcement, which lowers construction costs, increases production speed, and reduces noise and disruption in the surrounding areas of the construction site.
Doukakis 18 studied the effects of adding two kind of fibers, steel and polypropylene, on the fresh and mechanical properties of a LWSCC.Each fiber type had two different densities by volume creating a total of five mixes including the control.All mixes were tested for workability, passing ability, density, CS, elastic modulus, splitting tension, and FS.All tests were performed in accordance with the appropriate ASTM specification.Overall, fiber specimens performed better than the control in splitting tension, compression, and FS testing since they could hold a residual load.Effect on modulus of elasticity and workability was minimal.
Al-Hadithi et al 19 used paper shredder to cut soft drink bottles into rectangular pieces with the following fixed dimensions: net length of 40 mm, average width of 4 mm and thickness of 0.35 mm.The volumetric percentages of the PET fibers used in this study are 0.25%, 0.5%, 0.75%, 1%, 1.25%, and 1.5%.The physical properties of waste plastic fibers (WPFs) represented by elongation, aspect ratio, density, water absorption, were equal to 16%, 30, 1.38 kg/m 3 , 0 respectively.Steel stirrups replaced by CFRP strips for shear reinforcement.Results indicated that shear strength increased by 11.45% and 8.45% for the beams reinforced with CFRP strips and steel stirrups, respectively, at 1% fiber content.Similarly, shear ductility increased by 8.61% and 9.96% for the beams reinforced with CFRP strips and steel stirrups, respectively, with an increase of up to 1.25% in fiber content.
0][21] Choi et al 22 throw their research on effects of adding waste PET bottles aggregate on the properties of concrete found that, the 28-day CS of WPLAC with the replacement ratio of 75% reduces about 33% compared to the control concrete in the water-cement ratio of 45%.The density of WPLAC varies from 1940 to 2260 kg/m 3 by the influence of WPLA.The structural efficiency of WPLAC decreases as the replacement ratio increases.The workability of concrete with 75% WPLA improves about 123% compared to that of the normal concrete in the water-cement ratio of 53%.The adhered granulated blast furnace slag is able to strengthen the surface of WPLA and to narrow the transition zone owing to the reaction with calcium hydroxide.Another study by Jo et al reported that adding tire rubber substances resulted in the concrete's having elevated ductility in CS analysis as compared to the one with no tire rubber substances. 23he inclusion of an artificial aggregate manufactured using plastic waste to develop light-weight concrete was studied by Castillo et al. 24 Five separate mixes were designed, progressively increasing the amount of artificial aggregate.Fifteen percent of the natural aggregate by weight was replaced in this optimal mix, which equals more than 37% of the volume given the lower density of the manufactured aggregate compared to natural aggregate.The results indicated that plastic aggregates manufactured following shredding, palletization, and extrusion processes can be used to obtain lightweight concrete (1800 kg/m 3 ) while having relatively good CS properties (20 MPa at 28 days) 24 .
Mazaheripour et al. 25 studied the influence of introducing polypropylene fibers on the hardened and fresh characteristics of lightweight SCC (density between 1700 and 2000 kg/m 3 ).The obtained results indicated that polypropylene fibers do not affect the elastic modulus and CS.Nevertheless, using a higher volume fractions of polypropylene fiber which equal to 0.3% improved the FS by 10.7% and the tensile strength by 14.4% through splitting tensile strength analysis.

| STRUCTURAL BEHAVIOR OF SCC CONTAINING EPS IN FLEXURE
An experimental study conducted by Carbonari et al 26 deals with flexural behavior of light-weight sandwich panels with perpendicular connectors.Three experimental programs were performed to assess the influence of different support and loading conditions.The results obtained show that the connectors have a low contribution to the stiffness of the structure.The slabs tested show high deformability and a degree of cracking even under service loads.To improve the structural response, a reinforced connection between the slabs and their supporting elements should be used.Furthermore, a model is proposed to predict the failure of the panels. 26everal studies have focused on the material characteristics of LWC, SCC, and SCLWC with the aim of improving their durability and mechanical properties.Over the years, SCLWC has been used in a variety of structures; however, only a few studies have focused on the flexural and shear characteristics of SCLWC beams containing EPS, 26,27 as well as there is no studies deals with the incorporation of EPS and WPFs in LWC.This necessitates studies on LWSCC-based structural elements in terms of their structural performance, as well as an evaluation of the current design specifications for practical design.This study on the flexure performance of EPS-containing SCLWC beams will make a significant contribution to the existing technology.

| Materials
Ordinary Portland cement was used in this study, with a specific gravity of 3.15.This kind of cement conformed to the Iraqi Standard (IQS) No. 5/1984. 28Natural rounded gravel with a maximum size of 10 mm was used in this study.The gravel is cleaned and washed by tap water several times and allowed to dry in the air.Table 1 show the physical properties and grading of the coarse aggregate according to the IQS specification No. 45/84. 29The dry density of the coarse aggregate that was used in the study is 1650 kg/m 3 .Natural sand from a local region in the Anbar governorate was used as fine aggregate in this study.The grading and physical properties of the fine aggregates conform to the IQS specification No. 45/84 28 and are given in Table 2.The dry density of fine aggregate is 1750 kg/m 3 .Tap water was used in the casting of all specimens and in the process of curing.A superplasticizer was used in the modified mixes in the study.It meets the requirements for superplasticizer specified by ASTM C494 type F 30 The properties of the superplasticizer are given in Table 3.The study used silica fume (SF) with a specific gravity of 2.2 kg/m 3 and was conducted according to ASTM C1240-15.Expanded polystyrene beads, a commercially available spherical EPS bead that are essentially single sized were used.The grading shows that mostly 10 mm maximum size beads.EPS used in this study is white, with a loss on ignition of 100%, softening point between 80 and 100 C, and water absorption by immersion, after 28 days, between 1% and 3% volume.Table 4 show the grading for EPS.
Waste plastic fibers, the fibers were obtained by cutting WPFs, gathered directly from disposed Pa EPS beads were used, which are commercially available The fibers were made into piece for one aspect ratio by using heavy scissor.The thickness of WPFs was 0.8 mm.The aspect ratio of fibers ( 23) was adopted in this work.The Dimensions and physical properties WPFs strap fibers are given in Table 5.

| Mixing, casting, and curing procedures
The seven SCC mixtures presented in Table 6 were developed according to European Federation of Specialist Construction Chemicals and Concrete Systems (EFNARC). 32here coarse aggregate had been replaced by EPS from 10% to 100% by volume in order to get the best lightweight concrete design.The objective was to have an optimum density of 1600 kg/m 3 with 100% EPS replacement when WPFs were incorporated.Therefore, the ratio of fine aggregate to coarse aggregate to EPS varied slightly between the WPFs' contents.The control specimens without WPFs underwent the same tests as those with WPFs to compare the results with those without WPFs.Table 8 states that the amount of WPFs in concrete mixes was 0.25%, 0.5%, 0.75%, 1.0%, and 1.25%.4][35] SF was added to reduce the bleeding. 31Thus, the w/cm ratio was decreased to 0.4.In addition, superplasticizer was used as a to make the mixture more workable in all mixes.

| Casting
All molds were lubricated by Oil using a brush and reinforced for beam molds before the casting day; concrete rebar's spacers were utilized and the cover was assessed following the recommended specification. 36The samples were prepared in different shapes to study their fresh, hardened, and mechanical properties.The standard cubes 100 mm that contain WPFs were weighed with the aid of a sensitive balance and packed into five groups in plastic bags; the rest of the materials were weighed on a digital balance before being stored in dry containers for casting.The dry sand and saturated dry surface coarse aggregate were mixed by the rotary mixer at speed (29.5 rpm) for 3 min before adding the WPFs, depending on the volume proportion.The mixing was continued for 2 min only to distribute the WPFs throughout the mixture and avoid forming strap balls.Water was introduced into the mixture after all other components had been added, followed by continuous mixing for 4 min to achieve the best mix workability requirements.After mixing the concrete, it was poured into molds, cubes, prisms, and cylinders in two layer without vibration.The upper sides of the molds, cubes, and cylinders were smoothed using a hand trowel.The entire sample was covered with polythene sheets and allowed to cure in the laboratory for 24 h before being cured.casting, prisms100 Â 100 Â 500 mm 3 , cylinders 10 Â 20 mm 2 , and 15 Â 30 mm 2 , and cube specimens 100 mm, the specimens were placed in a curing room with a temperature of 23 C and a relative humidity of 90%.The specimens were then demolded after 24 h and kept in the curing room until it was time to use the specimens for testing.The curing of these specimens was conducted according to ASTM C192/ C192M. 37All tested beams were reinforced by steel reinforcement bars with different diameters (12, 10, and 8 mm) for longitudinal reinforcement and (8 mm) for transverse reinforcement (stirrups).Table 7 illustrates the properties of steel reinforcement according to ASTM A615/A615M-18e1. 38

| Concrete mixes
Self-compacting concrete mixtures presented in Table 6 were developed according to the guidelines of EFNARC (2002) using a large number of trial mixes.The coarse aggregate was totally replaced with EPS.Waste PET fibers were added by different volume of fraction (0.25%, 0.5%, 0.75%, 1.0%, and 1.25%).The objective was to have an optimum density of 1600 kg/m 3 with 100% EPS replacement when WPFs were incorporated.

| Test procedure
In this study, experimental investigations were carried out in three parts.In the first and second parts, investigations were performed on the fresh and hardened properties of concrete beams, considering different mix proportions.In the third part, a detailed experimental study was conducted on the flexural behavior of the proposed built-up reinforced concrete (RC) beams.Freshstate tests for self-compacting beams were performed within 15 min after the addition of the mixing water, based on standards and procedures of EFNARC guidelines. 32The slump flow and T-500 tests were performed according to the EFNARC guidelines 32 in order to determine the followability of SCC.In addition, V-funnel, and L-box tests were carried according to the EFNARC guidelines 32 out to check the filling and passing abilities of fresh concrete.A sieve segregation test was performed to determine the segregation index (SI). 32n the hardened-state tests, the specimens were demolded after about 24 h and exposed to the watercuring condition.Tests are performed at a 28-day age.The density values were determined according to the requirements of ASTM C642-13 39 for concrete with 28 days of age, using 100 mm cubic specimens.Three specimens were cast for each concrete mix developed.To determine the CS of all mix compositions, nine cubic specimens with a dimension of (100 Â 100 Â 100) mm 3 were fabricated and tested according to BS EN 12390-3. 40 digital compressive machine with a load cell capacity of 2000 kN (a loading rate of 0.3 MPa/s) was used to determine the CS of the samples.Three replicates of cubic specimens were utilized in the compressive tests.

| Flexural strength
This test has been completed by adopting ASTM C78/C78M-18 41 on beams that were cast for each of the seven concrete mixes.The results of this test using third point loading will provide an insight into the flexural tensile behavior of the fiber RC specimen by using the various data collected, such as: peak loads and the corresponding peak strengths.A load deflection curve was made for all the specimens, and the area beneath the curve was calculated as the flexural toughness of the specimen according to ASTM C1609/C1609M-19. 42he simply supported (100 mm Â 100 mm Â 500 mm) beam specimens were subjected to third-point loading.The beam was loaded until failure, and the maximum loading that the specimen could take was recorded as the peak load.

| Toughness
The approach for determining the flexural toughness of SCLWC is based on ACI Committee 544. 43The load- deflection curves for beams made of fiber-RC are closely similar to those of an elastic-plastic material. 43Toughness indexes from the flexural load-deflection diagram are shown in Figure 1.
Toughness indices according to ASTM Cl018-97 44 is a dimensionless parameter that defines the shape of the load-deflection curve.By including the percentage postcrack load drop values, the fingerprinting of the shape of the load-deflection curve can be further improved.Indices have been defined on the basis of three service levels (I 5 , I 10 , and I 20 ), identified as multiples of the first-crack deflection.The index is computed by dividing the total area under the load-deflection curve up to the given service level deflection by the area under the same curve up to the first-crack deflection.
The load-deflection curves were analyzed by using a recently developed post-crack strength (PCS) method, 45,46 which provides a more meaningful characterization scheme for fiber RC.The PCS method is a method of converting a load-displacement curve into an effective (or equivalent) FS curve using simple energy equivalence.

| Flexural beams
The experiments in this study were designed for the evaluation of the flexural behavior of LWSCC beams.RC beams have been produced from all concrete mixes, in order to compare the conduct of beams produced from new concrete under bending loads with those produced from classical SSC.To test the conformity of the RC beams produced from new concrete (structural lightweight mixes and no as well as) with the requirements of the American Concrete Institute code ACI 318-019, 47 21 RC beams were cast with adequate shear reinforcement to ensure flexural failure and tested.The beams were all designed as under-reinforced 12, 10, and 8 mm and were designated as Group A, Group B, and Group C, respectively.For all the beams, the dimensions were as follows: width = 100 mm, depth = 150 mm, and length = 1200 mm.Three configurations were used for the flexural reinforcement as earlier mentioned.All the beams were provided with a clear cover of 20 mm, while bar strips (8 mm) at 60 mm c/c were used as shear reinforcement.Figure 2 and Table 7 show the cross-sections and reinforcement configurations of the flexural beams.

| Specimens setup and instrumentation
The specimens were tested simply as supported beams at four-point loading conditions.Digital gauges were used to measure the deflections at the mid-span and loading point.The experimental setup and the positioning of the digital gauges for measuring deflection in the flexural reinforcement beams.
The load was incrementally applied from a hydraulic jack at 5 kN for each increment and constant rate of loading was 0.5 kN/s; at each increment, the load was kept constant for some time to monitor the crack pattern.Shear and flexural crack initiation and development at various stages were monitored and recorded during the test.The load-deflection response was monitored and recorded during the testing to failure.The test also revealed the general behavior of the beam in terms of crack development, crack patterns, failure modes, and mechanism of load transfer.

| RESULTS AND DISCUSSION
The results were presented on the fresh, hardened properties and flexural behavior of LWSCC beams.The description of the performance was based on loaddeflection response, while first crack load, crack width, and crack pattern development were discussed as well.The results of the rheological testing program of the seven mixes used in this study are illustrated in Table 9.The slump flow, T-500, V-funnel, L-Box, as well as segregation resistance (SR%) tests for fresh properties of concrete have been done after all concrete mixtures (R, E, E0.25, E0.5, E0.75, E1.0, and E1.25) have been mixed.
F I G U R E 1 Toughness indices from the flexural load-deflection diagram. 41

| Hardened state properties
The hardened properties of all SCC mixes have been tested in order to compare the proposed design method and mixing procedure.Various hardened properties tests like dry density, water absorption, and voids have been done, and the results are included in Table 8.This table shows the results of the LWSCC concrete mix compared with the control mix (R mix) as well as the E mix.The E1.25 mix, however, showed a greater dry density reduction in comparison to the R mix and the E mix.
From Table 8, it is clear to notice that, a decrease in dry density in comparison to mix (R) was obvious due to the incorporation of EPS as a replacement for coarse aggregate, which led to all mixtures being considered lightweight aggregate concrete, as shown by the presence of EPS in the specimen.The factor that caused the WPFs specimens to have lower values than the control specimen (R) and EPS specimen (E) is the air voids that were created once the concrete batch was mixed.The increased amount of WPFs could have caused the fibers and cement paste to not mix well, therefore not creating a dense concrete matrix.Thus, this could have caused more air to escape, which would have reduced the density of the mixture.The same result was noticed in the work of Doukakis, 2013. 18From Table 8, it can be seen that all concrete manufactured from concrete mixtures containing EPS and reinforced with WPFs (i.e., E, E0.25, E0.50, E0.75, E1.00, and E1.25) can be classified as a lightweight concrete combination of normal weight and lightweight aggregates according to ASTM C330/C330M-14. 48The best percentage of reduction in the density of concrete as a result of the use of EPS and WPFs was represented in the concrete mix (E1.25), and the percentage of decrease was equal to 38.46%.

| Mechanical properties
Table 9 shows the summary of compressive and FSs for all mixtures.The table shows the strengths at the age of 28 days of curing.The reported values of compressive and FSs are averages of three specimens prepared from each mix.To test the CS of concrete cubes of (100 Â 100 Â 100) mm, the procedure outlined in BS EN 12390-3 49 has been used.The former results are then multiplied by a factor equal to (0.83) to find the equivalent CS (f 00 c) for cylinders with (150 Â 300) mm according to the ASTM C39 50 specification.As seen in Table 8, and according to ASTM C330/C330M-14, 48 only three mixes can be classified as structural lightweight concrete combinations of normal weight and lightweight aggregates, and these are E0.50,E0.75, and E1.00.The FS test has been completed by adopting ASTM C78/C78M-18 41 on beams that were cast for each of the seven concrete mixes.
The FS of LWSCC mixtures varied from 2.36 to 3.57 MPa at 7-day, 2.86-3.88MPa at 28-days, and 3.70-4.35MPa at 90-day.These values are presented in Table 9, with the highest values recorded for E-LWSCC mix at 90 days, while the lowest was recorded with mix made with EPS aggregate (E mix).
Figure 3 shows a comparison of the FSs of three different LWSCC mixtures and the control sample at different ages.Due to the influence of the size, quality, and volume of coarse aggregate on the FS of LWSCC mixes, the EPS-containing mixes showed higher strength since Flexural strength test results of all mixtures for 7, 28, and 90-day of the lightweight self-consolidating concrete (LWSCC) improves, which will agree with previous studies. 50,5100% coarse aggregate volume as EPS was used in these mixes compared to WPFs mixes.Figure 3 also showed the FS of LWSCC to increase with the WPFs content up to 1.0% (E1.0) as the fibers become densely spaced with increased WPFs content, which may limit the development of micro cracks within the brittle matrix and consequently increase the FS of LWSCC. 51,52Moreover, the bonding property of plastics is low and can cause a decrease in the FS at the highest WPFs content (E1.25) as depicted in Figure 3. Increases in the plastic content allow more free water around the particles, which weakens the interaction between the plastic and the paste and causes the formation of a less dense zone with large voids and poor adhesion capability. 49Therefore the FS is apparently reduced at a higher fiber content of >1.25%.

| Flexural toughness
The toughness indices for control and LWFRSCC first crack areas were investigated as seen in Figure 4. Load deflection diagrams were plotted for all the specimens tested.The first crack loads were taken as the value of the loads when the load deflection diagrams started to deviate from linearity as defined by the ACI Committee F I G U R E 4 Post-crack strength analysis of self-compacting concrete (SCC) and lightweight self-consolidating concrete (LWSCC) mixtures 544. 43Based on this, the first crack load and first crack area were determined for both control and LWSCC beams.The calculated values of toughness indices (I5, I10, and I20) for all mixtures are given in Table 10.
When the WPF content is increased from 0.25% to 1.25%, the I 5 values increase by 180%, 28.57%, 11.11%, 7.5%, and 104.65%, respectively as compared with reference mix.Similar improvements can be for I 10 and I 20 values.The ratios of I 10 /I 5 and I /I 10 are good indicators of the plastic behavior of concrete specimens.The values equal to 2 for both I 10 /I 5 and I 20 /I 10 indicate perfect plastic behavior. 53The current study indicates that E0.50 and E0.75 mixtures have the perfect plastic behavior.The maximum displacement corresponds to the maximum load for the control mix, and this gradually increases based on the number of WPFs, respectively.As can be seen in Figure 6, the specimen with 1.25% of WPFs (E1.25) has a higher area under the load versus displacement curve, whereas the control specimen (R) has a lower area under the load.The results obtained in this investigation indicate that, in terms of flexural toughness indices and parameters, the E1.25 mix with 1.25% WPFs gives the best performance.In general, it is observed that with the increase in WPFs content, the flexural toughness bending behavior of LWSCC-RC is also increased.
On the other hand, the reference mix specimens showed higher values for the peak load when compared to the specimens containing plastic fibers.Compared with the reference concrete (R), the value of the maximum load decreased in proportions (34%, 46.5%, 46%, 66%, 87%, and 47.8%) for mixtures (E, E0.25, E0.5, E0.75, E1.0, and E1.25), respectively.That means, replacing coarse aggregate with EPS leads to decrease in peak load value, whereas adding WPFs leads to more decrease in peak load value.
The flexural behavior of the produced LWSCC and SCC beams in this study was also studied experimentally.Seven beams were produced and tested for each group without shear reinforcement under four-point loading to failure.Six beams were produced with LWSCC and SCC at three different cross-sections.
Load-deflection behavior for this test, LWSCC beams were evaluated under four-point loading.For each beam, a shear span-to-effective depth ratio (a/d) of 2.5 was maintained.All the beams were provided with adequate shear reinforcement except at the zeroshear region of 300 mm.Table 11 indicate the experimental results for the bending behavior of all grouped tested beams, showing failure modes, loads at first crack, ultimate load, maximum crack width, and ultimate deflection, while Table 12 shows ductility of the tested beams.Figures 5-14 show load-deflection curves for all grouped tested beams.The main difference among groups is the flexural reinforcement ratio.Three steel reinforcement ratios were used (Ꝭ = A s /bd, where A s = area of steel reinforcement, b = width of the beam, and d = effective depth of steel reinforcement) as seen in Table 7.The behavior of loaddeflection curves is divided into three stages: 1.The curve in the first stage has a constant slope (linear) and is called the elastic behavior.At this stage, the stresses are distributed linearly through the depth of the beams and the strain values of the material are relatively small.This stage end when the first crack appeared.2. Inclined cracks appeared in the second stage on both sides of the beams.The behavior of the load-deflection curve converts from elastic (linear) to plastic (non-linearity) because the rate of the increase in load is less than the increase in deflection value.This stage end when the steel reinforcement yielding.3. The load-deflection curve in the third stage becomes nearly horizontal due to the high value of deflection.In the post yield phase, the depth of the neutral axis decreases significantly, thus increasing the curvature and deflection immediately after the reinforcing steel yields.
In addition, the FS of the beam reached its maximum,  7 shows the load deflection relationship for these beams.

| Mix E
The test results for beams of no WPFs contents only showed that the first crack occurs at 5.2, 5.1, and 5 kN and the deflection is equal to 1, 1.1, and 0.8 mm, the ultimate load was 38.2, 34.08, and 28.88 kN with ultimate deflection equal to 11.43, 9.6, and 8.9 mm for Group A, Group B, and Group C, respectively.Figure 8 shows the load deflection relationship for these beams.

| Mix E0.25
The test results for beams of 0.25% WPF content showed that the first crack occurs at 5, 5, and 5 kN and the deflection is equal to 1.3, 0.7, and 1.3 mm.The ultimate load was 30, 34.96, and 24.51 kN with ultimate deflection equal to 8, 9, and 8.5 mm for Group A, Group B, and Group C, respectively.Figure 9 shows the load deflection relationship for these beams.

| Mix E0.50
The test results for beams of 0.50% WPF content showed that the first crack occurs at 5, 5. to 7.6, 9.3, and 7.9 mm for Group A, Group B, and Group C, respectively.Figure 10 shows the load deflection relationship for these beams.

| Mix E0.75
The test results for beams of 0.75% WPF content showed that the first crack occurs at 9, 10, and 5 kN and the deflection is equal to 1.8, 1.7, and 2.1 mm.The ultimate load was 30, 43, and 30.5 kN with an ultimate deflection equal to 7.7, 9.3, and 7.7 mm for Group A, Group B, and Group C, respectively.Figure 11 shows the load deflection relationship for these beams.

| Mix E1.0
The test results for beams with 1.0% WPF content showed that the first crack occurs at 9.8, 10, and 10.1 kN and the deflection is equal to 1.6, 1.9, and 1.7 mm.The ultimate load was 44, 45.2, and 27 kN with ultimate deflection equal to 6.4, 9.6, and 9.8 mm for Group A, Group B, and Group C, respectively.
Figure 12 shows the load deflection relationship for these beams.

| Mix E1.25
The test results for beams of 1.25% WPF content showed that the first crack occurs at 10, 10, and 8 kN and the deflection is equal to 1.6, 2, and 2.2 mm.The ultimate load was 57, 50, and 31.81kN with ultimate deflection equal to 11.02, 10.6, and 8.15 mm for Group A, Group B, and Group C, respectively.Figure 13 shows the load deflection relationship for these beams.Figures 12, 13, and 14 show the force to mid-span deflection of all the group's beams.All seven beams in each group had a flexural mode of failure with vertical flexural cracks forming below the loading points.These cracks are characteristic of elongation of the reinforcement into the plastic region, as confirmed by the attached strain gauges.After forming flexural cracks, variation in the slope of the load deflection curve was specific and the slope of the post-cracking response was reasonably linear until the yielding of the reinforcements.The stiffness of the beam changed dramatically when the yielding of reinforcement occurred.The load-deflection curve also exhibits large plastic deformations as the steel yields and has considerable ductility.As the control beam test (R) and comparison benchmark to lightweight concrete beams, the flexural failure modes of all the beams indicate that BS EN 1992-1-1:2004 + A1:2014 54 code provisions for shear remain conservative when applied to normal weight concretes made with regular dense rockbased aggregates.The high steel reinforcement ratio (Ꝭ = 0.0182), as shown in the behavior of the Group A beams, had a role in raising the value of the ultimate failure load compared to the beams of the less reinforced Groups B and C. The replacement of coarse aggregates with EPS led to a reduction in the ultimate load for all steel reinforcement ratio.This is evident by comparing the maximum load of type R beams with beams of type E for all three groups (A, B, and C).The beams manufactured from the reference concrete (R beams) showed the highest deflection values for all the different steel reinforcement ratio, that is, for the three groups (A, B, and C).
In Group B, that is, when using a medium steel reinforcement ratio (Ꝭ = 0.0125), the plastic waste fibers showed an important role in increasing the ultimate load of the RC beams containing WPFs compared to the RC beams produced from the reference concrete containing EPS.
The same behavior can be generalized to the Group A. The group contains the RC beams with the highest  percentage of reinforcing steel (Ꝭ = 0.0182), for all percentages of WPFs except for the two percentages of fiber (V f = 0.25 and V f = 1.0).As for Group C with the lowest reinforcing value (Ꝭ = 0.0080), the effect of adding plastic waste fibers was less clear than the previous two groups (A and B).
In general, the replacement of coarse aggregates with EPS and the addition of WPFs had a role in reducing the deflection for all reinforcing steel ratios (i.e., A, B, and C groups).

| Ductility behavior of LWSCC beams
Ductility refers to the ability of a component to deform without significantly causing any loss of strength.Ductility is also defined by the curvature ductility index (DI), which is considered as the ratio of deflection at failure/ ultimate stage (Du) to defection at first yielding of steel (Dy).The DI values for LWSCC flexural beams as estimated from the Dy/Du derived from the load-deflection responses are presented in Table 11.The crushing strain of concrete generally exerts a strong influence on the DI.At DI values of more than 1.5, the ductility of LWSCC beams is normally good.The ductility of the LWSCC was affected by the tension reinforcement ratio.Most of the RC beams containing WPFs had ductility values greater than 1.5, that is, they have good ductility.The two RC LWSCC beams (Group A, E0.25 and Group B, E1.00) had the ductility values less than 1.5, but the ductility values were very close to the good classification of good ductility, that is, close to 1.5.The LWSCC beam (E1.0) with the lowest reinforcement ratio was found to exhibit the maximum DI value (2.08).The study by Teo et al. 55 observed a similar trend of ductility decline with increasing reinforcement ration in OPS-reinforced LWA concrete beams.All beams exhibited considerable amount of deflection which provided ample warning to the imminence of failure.

| CONCLUSIONS
1.The results proved the possibility of producing lightweight concrete from the use of EPS waste and WPFs, three of which are structurally classified as lightweight concrete combinations of normal weight and lightweight aggregates according to the specifications requirements of ASTM330/330M-14.2. The use of EPS with WPFs had a significant positive effect in reducing the density of concrete, and the highest percentage of reduction was equal to 38.46%.3. Using WPFs had a positive effect in increasing the flexural toughness of concrete prisms, and the maximum increment was equal to (180%) compared with those made from the reference mix.The results obtained in flexural toughness tests showed that in terms of flexural toughness, lightweight SCC with 1.25% WPFs provides the best flexural toughness performance.Concrete with a 100% EPS replacement as coarse aggregates and 0.25% WPFs offers slightly lower parameters and display positive effect.On the other hand, adding WPFs had a negative effect in decreasing the load peak of concrete prisms.4. The flexure behavior of all SCLWC flexural beams exhibited typical structural patterns as the beams were all under-reinforced.Observable, the yielding tensile reinforcement occurred before the compressed concrete was crushed in the pure bending region.Increases in the WPFs content decreased the maximum cracking width of lightweight self-compacting concrete fiber reinforced concrete beams from all the studied groups.5. SCLWC beams exhibited good ductility as all the beams showed observable level of deformation prior to failure.6.No noticeable difference in cracking patterns was observed between the different contents of WPFs of lightweight SCCs.

DATA AVAILABILITY STATEMENT
The data that support the findings of this study are available from the corresponding author upon reasonable request.ORCID Majid Al-Gburi https://orcid.org/0000-0002-9987-0174

F I G U R E 2
Detailed dimensions of tested beam.T A B L E 8 Geometry and reinforcement configuration of the flexural beam.

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I G U R E 7 Load-deflection relationship for all groups E0.25 mix with crack patterns.

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Load-deflection relationship for all groups E0.5 mix with crack patterns.
R E 9 Load-deflection relationship for all groups E0.75 mix with crack patterns U R E 1 0 Load-deflection relationship for all groups E1.0 mix with crack patterns.

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I G U R E 1 1 Load-deflection relationship for all groups E1.25 mix with crack patterns.

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Load-deflection curves for group A tested beams.Load-deflection curves for group B tested beams.

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I G U R E 1 4 Load-deflection curves for group C tested beams. 31 T A B L E 1 The gradient and physical properties of used coarse aggregate.
T A B L E 2 Sieve analysis for fine aggregate (sand).T A B L E 4 Sieve analysis for expanded polystyrene beads (EPS).Maximum particle size (mm) 10 - Dimensions and physical properties of waste plastic fibers.
Flexural toughness indices of all tested specimens.
T A B L E 1 0 1, and 5.2 kN and the deflection is equal to 1.2, 1.1, and 1.6 mm, the ultimate load was 30, 42, and 31 kN with ultimate deflection equal T A B L E 1 1 Experimental results for bending behavior of the tested beams.
Ductility of the tested beams.
F I G U R E 5 Load-deflection relationship for all groups R mix with crack patterns