Microsoft Word - ETASR_V12_N6_pp9692-9696 Engineering, Technology & Applied Science Research Vol. 12, No. 6, 2022, 9692-9696 9692 www.etasr.com Salahaldeen & Al-Hadithi: The effect of adding EPS on the hardened properties……. The Effect of Adding Expanded Polystyrene Beads (EPS) on the Hardened Properties of Concrete Aya Sabah Salahaldeen Department of Civil Engineer University of Baghdad Baghdad, Iraq aya.arif2001m@coeng.uobaghdad.edu.iq Abdulkader Ismail Al-Hadithi Department of Civil Engineer University of Anbar Ramadi, Iraq abdulkader.alhadithi@uoanbar.edu.iq Received: 21 August 2022 | Revised: 9 September 2022 | Accepted: 10 September 2022 Abstract-This study investigated the possibility of producing lightweight concrete using Expanded Polystyrene Beads (EPS), using one reference and five light concrete mixes by replacing coarse aggregates with EPS grains in five volumetric ratios: 20, 40, 60, 80, and 100%. The properties of hardened concrete of all mixed specimens, such as compressive strength, flexural strength, and density, were evaluated. The results showed that the addition of EPS caused an apparent reduction in the mechanical properties of concrete. The compressive strength at 28 days of curing ranged from 13.6 to 1.96MPa, while the rupture modulus ranged from 2.26 to 0MPa. Adding EPS grains as coarse aggregates led to a decrease in the concrete's weight. Replacing the coarse aggregates with EPS grains resulted in lightweight concrete with a density of 1086.5kg/m 3 . Keywords-lightweight concrete (LWC); coarse aggregates; Expanded Polystyrene Beads (EPS); properties of hardened concrete I. INTRODUCTION Concrete is an artificial material used to construct various civil engineering structures [1]. Concrete is the most commonly used substance in construction and can be used as stand alone mass concrete, reinforced concrete, or prestressed concrete when combined with steel [2]. For every ton of cement produced, one ton of carbon dioxide (CO2) is emitted into the atmosphere. Cement manufacturing is responsible for 5% of anthropogenic CO2 emissions [3]. Cement production produces a significant amount of CO2 and requires a large amount of energy during the manufacturing process. Given that Pakistan is already facing an energy crisis, the high energy consumption in cement production puts additional pressure on its energy sector. As a result, the price of cement is rising daily. Furthermore, waste disposal and the restoration of concrete components after demolition have negative environmental consequences. As a result, the use of this waste reduces cement manufacturing and energy consumption while also helping protect the environment [4]. One of the drawbacks of traditional concrete is its high self-weight. The density of regular concrete ranges between 2200 and 2600kg/m 3 making it an uneconomical structural material. Several attempts have been made in the past to reduce the self-weight of concrete to increase its efficiency. Lightweight Concrete (LWC) is a type of concrete with a density ranging from 300 to 1850kg/m 3 [5]. Since LWC was first used approximately two thousand years ago, several lighter structures were built, particularly in the Mediterranean region. The three most important structures built during the Roman Empire are the Colosseum, the Port of Cosa, and the Pantheon Dome [6]. The use of LWC in buildings, structural and non-structural, as construction material must have specific characteristics that meet the requirements of strength and performance for the application. Before using any material in construction, there is a need to study its mechanical properties to determine its suitability [7]. Due to its low density, which offers tremendous benefits by reducing the cross sections of the components, there is an increase in the demand for LWCs in many modern architectural constructions [7]. There are two categories of lightweight aggregates: natural, such as diatomite, volcanic cinders, etc., and industrial such as expanded shale, clay, and slate. Polystyrene is an industrial material with a density less than 300kg/m 3 and no absorption properties [8-9]. Polystyrene has a closed cell structure, is stable, has low density, and is not absorbent or hydrophobic [10-11]. Concrete can be used for all parts of a building (structural and non-structural) as a very lightweight material by altering the percentage ratio of its aggregates [12-13]. Unlike lightweight industrial aggregates, polystyrene is commercially available everywhere. Most polystyrene manufacturing facilities are located in Europe and Russia [14]. The effects of adding EPS to cement mortar and concrete have not been extensively studied. This addition leads to a decrease in the density and mechanical properties of both cement mortar and concrete [15-16]. Ultra-high-performance concrete and EPS beads composite sandwich plates were investigated in [17], examining the use of these sandwich plates in high-rise structures. Because of their low density and high compressibility, EPS beads are frequently used as filling materials in earthquake buffers [18-20]. This study aimed to investigate the production of LWC using EPS as coarse aggregate, carrying out several tests to examine the effect of adding EPS as coarse aggregate with different volume percentages on the properties of the new LWC. Corresponding author: Aya Sabah Salahaldeen Engineering, Technology & Applied Science Research Vol. 12, No. 6, 2022, 9692-9696 9693 www.etasr.com Salahaldeen & Al-Hadithi: The effect of adding EPS on the hardened properties……. II. EXPERIMENTAL SETUP A. Cement All specimens were cast using Ordinary Portland Cement (OPC) Type I throughout the experiment. This kind of cement complies with the Iraqi specification 5/2019 [19]. Table I shows its physical attributes and chemical composition. B. Fine Aggregates Sand from the Al-Ekhadir area (Karbala city) was used as fine aggregates, as shown in Figure 1. This sand is classified as zone 2 and meets the physical and chemical requirements of the Iraqi standard 45/1984 [20], as shown in Table II. Fig. 1. Fine aggregates (left) and coarse aggregates (right). C. Coarse Aggregates Natural gravel from the Al-Nibaee region with a nominal aggregate size of 5-10mm, shown in Figure 1, was used as coarse aggregates in all mixes. Table III shows that the physical and chemical parameters of the coarse aggregates comply to the Iraqi standard 45/1984 [20]. D. Water Potable (tap) water, obtained from the laboratory, was used for mixing and curing. This water meets the requirements of the Iraqi standard 1703 [21]. E. Expanded Polystyrene Beads (EPS) This study used spherical-shaped EPS beads with a maximum nominal size of 10mm to replace coarse aggregates. Table IV depicts the gradient and physical properties of EPS beads, shown in Figure 2. Fig. 2. Expanded Polystyrene Beads (EPS). F. Superplasticizer (SP) A superplasticizer called Sika ViscoCrete 5930, which complies with the ASTM C494 type G [22] criteria, was used in the adjusted mixes, and Table V shows its features. TABLE I. PHYSICAL AND CHEMICAL COMPOSITION OF CEMENT Physical properties Test result Limits of IQS 5/2019 [19] Setting time: -Initial setting (min) -Final setting (hrs.) 106 4.83 45 min 00 hrs. max Comp. Str. (MPa): 2-days 28-days 11.25 33.31 Min. 10 Min. 32.5 Chemical properties Oxide composition Result Limits of IQS 5/2019 [19] (����) 21.62 No limited (�����) 5.94 No limited (� ���) 3.32 No limited (CaO) 61.55 No limited L.S.F. % 0.86 No limited (MgO) 2.85 Max. 5 Sulfate (SO3 %) max C�A<5% Not applicable 2.5 C�A >5% 2.25 2.8 (L.O.I.) 1.07 Max. 4 (I.R.) 0.88 Max. 5 (C�S) 35.11 No limited (C�S) 35.07 No limited (C�A) 10.13 No limited (C AF) 10.09 No limited TABLE II. FINE AGGREGATES SIEVE ANALYSIS Limits of [20] (Zone 2) Passing % Sieve Size (mm) 100 100 10 90-100 92 4.75 75-100 85 2.63 55-90 56 1.18 35-59 42 0.6 8-30 13 0.3 0-10 5 0.15 Physical and chemical properties Limits of Iraqi standards Test results Physical characteristics ----- 2.5 Specific gravity 0.5% (max) 0.4% (SO3 %) ----- 0.7% Absorption (%) TABLE III. COARSE AGGREGATE'S PROPERTIES Sieve Size (mm) Test Results Limits of [20] 14 100 90-100 10 75.1 50-85 5 1.2 0-10 2.36 -- No limited SO�% content 0.092 Max. 0.1% TABLE IV. SIEVE ANALYSIS AND PROPERTIES OF EPS Sieve Size Passing % ASTM C330 12.5mm 100 100 9.5mm 91 80-100 4.75mm 6.5 5-40 2.36mm 1.5 0-20 Specific gravity -- -- Water absorption 0 -- Maximum particle size (mm) 10 -- TABLE V. PROPERTIES OF SUPERPLASTICIZER [23] Density 1.08 kg/l pH 8.0 ±1.0 Chloride content NIL (EN934-2) Engineering, Technology & Applied Science Research Vol. 12, No. 6, 2022, 9692-9696 9694 www.etasr.com Salahaldeen & Al-Hadithi: The effect of adding EPS on the hardened properties……. III. MOLDS, MIXING, AND CASTING Three 100×100×400mm prism samples were produced for each group of 7, 14, and 28 days of curing to test the flexural strength and three 100×100×100mm cube samples with ages 7, 14, and 28 days were constructed to test compressive strength. Before placing the materials, the internal surface of the mixer was cleaned and wet. To ensure even dispersion of the polystyrene, the raw materials were first thoroughly combined and dried for about 3 minutes. Afterward, water was gradually added while mixing to produce a smooth and flowing liquid. The mixing process was extended for 3 minutes to create a uniform and consistent concrete. This process was performed in the concrete laboratory of Baghdad University's College of Engineering. All concretes were blended using a planetary mixer, shown in Fig. 4. The mixture was poured into oiled molds, which were then vibrated on a vibrating table for 1 minute to improve compaction and reduce air bubbles. The samples were demolded after 24 hours and placed in water for curing before testing. Fig. 3. Mixing of concrete. IV. CONCRETE MIX This study used 1 reference and 5 different concrete mixes to create the samples. Concrete was produced with a water/cement ratio of 0.45 and a coarse aggregate ratio of 1:1.6:3.12, by weight, of OPC. Table VI shows the details of the samples. TABLE VI. MIX OF 1m3 OF CONCRETE Mix Code R E20% E40% E60% E80% E100% Cement (kg/��) 401 401 401 401 401 401 SP (kg/��) 1.2 1.2 1.2 1.2 1.2 1.2 Fine aggregates (kg/��) 643 643 643 643 643 643 Coarse aggregates (kg/��) 1254 1002 753 501 250 0 EPS (kg/��) 0 2 4 6 8 10 Water (kg/��) 180 180 180 180 180 180 V. TEST RESULTS AND DISCUSSION A. Density The quantity and density of lightweight aggregates are two of the most crucial elements in regulating a variety of physical properties in LWC. Due to the low density of polystyrene, the density of LWC falls as polystyrene volume increases [24-25]. Table VII shows the densities of the samples and Figure 4 shows their density variation with age. TABLE VII. DENSITY TEST RESULTS Mix Code 7 days 14 days 28 days R 2550 2573 2589 E20% 2266 2283 2295 E40% 1944 1975 1984.5 E60% 1615 1627 1635 E80% 1356.5 1400 1422.5 E100% 1035 1055.5 1086.5 Fig. 4. Variation of density with age B. Compressive Strength According to Figure 5, the compressive strength gets stronger with curing time. This rise is the result of the cement hydration process becoming more advanced with time. Figure 6 and Table VIII both provide a comparison of the compressive strengths of several specimens at 7, 14, and 28 days of age. TABLE VIII. COMPRESSIVE STRENGTH TEST RESULTS Mix Code 7 days 14 days 28 days R 25.7 33.11 42.4 E20% 9.67 10.12 13.6 E40% 6.04 9.29 10.88 E60% 3.47 3.62 4.08 E80% 3.42 3.62 3.86 E100% 1.36 1.81 1.96 Fig. 5. Variations of compressive strength with age per sample. Figure 6 shows that the concrete containing EPS had a decrease in compressive strength when the P/Agg ratio reached 20% or higher. As EPS increased, the compressive strength decreased. In the case of higher-density concrete mixes, those that contained less polystyrene typically had higher strengths, but compressive strength decreased when the polyester content was greater than 80% of the aggregate. This is because the polystyrene fills in the gaps left by the absence of coarse aggregates. In addition, the compressive strength of Engineering, Technology & Applied Science Research Vol. 12, No. 6, 2022, 9692-9696 9695 www.etasr.com Salahaldeen & Al-Hadithi: The effect of adding EPS on the hardened properties……. polystyrene is lower than that of coarse aggregates. Similar to the conventional concrete, it is evident that strength declines as polystyrene content increases. Figure 6 shows the variation in compressive strength per sample and Figure 7 shows the compressive strength test procedure. Fig. 6. Variation of compressive strength with polystyrene content %. Fig. 7. Compressive strength test. C. Flexural Strength Figure 8 shows that all prisms made of concrete mixtures exhibited a steady increase in flexural strength over time. Figure 8 and Table IX show a comparison of the variance in flexural strength values with different polystyrene content percentages at 7, 14, and 28 days of age. Fig. 8. Variation of flexural strength with age. TABLE IX. RESULTS OF FLEXURAL STRENGTH TESTS Mix Code 7 days 14 days 28 days R 3.72 3.85 6.01 E20% 1.13 1.52 2.26 E40% 1.71 2.09 3.43 E60% 0.73 0.93 1.09 E80% 0.28 0.36 0.42 E100% 0 0 0 Figure 9 shows the change in flexural strength after 7, 14, and 28 days, and Figure 10 shows the flexural strength test procedure. Figure 9 shows that the flexural strength of concrete containing polystyrene decreased when the P/Agg ratio was 20% or higher. This could be because lower-density concrete has lower flexural strength as it contains higher amounts of polystyrene. Figure 9 illustrates how higher-density concrete mixes with lower amounts of polystyrene typically had a higher flexural strength. However, flexural strength decreased when polyester content was greater than 80% of the aggregates. This is because polystyrene fills in the gaps left by the absence of coarse aggregates and has lower flexural strength than coarse aggregates. Fig. 9. Variation of flexural strength with polystyrene content %. Fig. 10. Flexural strength test. VI. CONCLUSION This study investigated the compressive and flexural strengths of concrete with various proportions of EPS beads replacing coarse aggregates. The results showed that:  As the polystyrene/aggregate ratio increases, lightweight concrete's compressive strength decreases. Engineering, Technology & Applied Science Research Vol. 12, No. 6, 2022, 9692-9696 9696 www.etasr.com Salahaldeen & Al-Hadithi: The effect of adding EPS on the hardened properties…….  As the polystyrene/aggregate ratio increases, the density of the lightweight concrete mixes decreases. 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