Use of Polystyrene as Construction Material

Transcription

1 Use of Polystyrene as Construction Material Mr.Ashvani Singh* a, Mr.Y.Naveen b a Research Scholar School of Engg. & I.T. Department of Civil Engg., MATS University Raipur, India; b Assistant Professor School of Engg. & I.T. Department of Civil Engg., MATS University Raipur, India ABSTRACT This paper focuses light on the use of polystyrene as a construction material. This is a synthetic aromatic polymer made from liquid petrochemical monomer styrene. Polystyrene can be rigid or foamed and is one of the most widely used plastics. This temperature dependent behavior is exploited for extrusion, and also for molding and vacuum forming. Expanded Polystyrene beads are non-absorbent, since their cells are closed.it is easy to compress also. Lightweight concretes (LWCs) can be used in various construction fields. It can be used for repairing wooden floors of old buildings, carrying walls of low thermal conduction, floating quay, etc. For the first applications, the lightest possible material is used, i.e., usually it has a specific gravity of 0.5, the strength being of less importance. Keywords: Polystyrene, Construction, Materials, Polymer, Concrete, Temprature, Thermal 1. INTRODUCTION Structural lightweight concrete provides vital improvement in terms of technical, economic and environmental aspects [1-3]. Application of lightweight concrete significantly reduced the dead load of structures and relevantly reduced the cross-section of structural elements (i.e. columns, beams, braces and plate) and foundation size. Moreover, longer spans, thinner sections and better cycling load response can be obtained by using lightweight concrete [4]. Generally, lightweight concrete is instrumental to effectively reduce the risk of earthquake damage as the earthquake acceleration and its magnitude is significantly affected by the weight of a structure. The factors such as lower density, higher strength/weight ratio, and lower coefficient of thermal conductivity, better fire resistance, improved durability properties, better tensile capacity and sound insulation characteristics are considered as advantages of lightweight concrete compared with normal concrete. However, the parameters such as bulk specific gravity, unit weight, maximum size and particles shape, texture surface, strength of lightweight particles, moisture content and water absorption ratio considerably affect the propertiesof lightweight concrete [5,6]. Lightweight concretes (LWCs) can be used in various construction fields. It can be used for repairing wooden floors of old buildings, carrying walls of low thermal conduction, floating quay, etc. For the first applications, the lightest possible material is used, i.e., usually it has a specific gravity of 0.5, the strength being of less importance. But for some structural applications, a compressive strength higher than 40 MPa is sometimes necessary, which leads the designer to optimize a material with a specific gravity close to 1.8. In such a case, lightweight aggregates, such as expanded glass or clay, take part in the resistance of the composite. The possibilities offered by new cement-based materials suggest that it is possible

2 to improve the compressive strength versus the specific gravity, or to reach equivalent strength for lower specific gravity.it is proposed to use very lightweight inclusions, like expanded polystyrene(eps), having a specific gravity of about 0.02 in an ultra-high strength matrix having a strength higher than 130 MPa. However, the mechanical behavior of such a material is quite different from that of an ordinary LWC. It is known that the stress distribution within a granular cement-based composite depends on the sizes of the inclusions and on the respective modulus of the matrix and of the inclusions. When the aggregate has a modulus higher than that of the matrix, stress concentrations appear in the vicinity of the aggregates. Dealing with very lightweight aggregate, like EPS, having a negligible modulus, the twophase models are in their limit of applicability. Another way is to refer to models based on porosity, assuming that the concrete is described as a matrix containing voids (EPS spheres).the aim of this report is to achieve a mix design for Lightweight EPS Concrete with density lesser than 1800kg/m³ and enough high compressive strength so that it can be used in construction purpose. Fig 1.1 Polysterene 2. APPLICATIONS OF LIGHTWEIGHT CONCRETE Lightweight structural concrete is used in construction because it s lightweight with high strength properties. Particular types of structures such as shells and roofs can be built efficiently with lightweight strong concrete. There are various type of aggregates can be used to produce lightweight concrete, such as expanded shale, polystyrene beads, clays, slates, slag, and pumice or scoria, which are naturally occurring volcanic aggregates. Basically the material used depends on availability of lightweight materials. In San Miguel, for example, a type of pumice (espumilla orarenilla) which is locally available was used to make lightweight concrete for walls and roofs. Lightweight concrete having a good resistance to heat and sound was used as soundproofing material in subway stations (Shah, S.P. and Ahmad, S.H.,1994). In Germany, no-fines concrete was used. In this concrete, the aggregate cord-holes are covered with a thin cement paste layer and thus are bonded together at point-to point cement contacts [7]. Approximately 15% of the wall building block production in

3 Germany is made from no-fines lightweight concrete. In Hong Kong, four types of lightweight concrete (LWC) are commonly used. They are autoclave aerated concrete (plus lime), autoclave aerated concrete (plus fly ash), concrete with synthetic aggregate Leca (light expanded clay aggregate) and concrete with polystyrene beads. Lightweight concrete was introduced in Hong Kong for partition walls in public housing. Recently, lightweight concrete has a wide range of applications. However, in Hong Kong it is mostly limited to the use in non-load bearing partition walls.in Armenia, being in an earthquake region, Armenian engineers learned early the advantages of reducing the density of the concrete in order to reduce the mass of the structure and thereby can reduce lateral forces. The advantages of High Performance Lightweight Concrete also have demonstrated for offshore platforms, which are currently used in Japan, USA, UK, Canada, Norway, and Australia [8]. In New South Wales and Queensland, in Australia, lightweight concrete is used as a sound barrier. Concrete panels are used as a noise abatement system to reduce traffic and pavement noise originating from freeways. This 10 km freestanding reflective noise wall is made from 4000 x 600 mm2 panels, which are stacked horizontally to varying acoustic design heights 3. APPLICATION OF POLYSTYRENE BEADS IN CONCRETE Despite its most application in packaging industry [9], polystyrene beads are lightweight material which can be corporate with concrete mixture to make lightweight concrete. However, polystyrene beads have its drawbacks when incorporating in concrete mixture: (a) It is very light which can cause segregation in mixing. (b) Its hydrophobic (difficult to wet when mixing) characteristic, so chemical treatment on its surface is needed. Hence, it is low in strength, poor in workability and slump (in the fresh concrete state). Therefore, generally it is used in combination with other materials like steel (to make sandwich panels) which usually used for cold store construction, as the expanded polystyrene is good as a thermal insulation. Due to its good energy absorbing characteristics, polystyrene concrete can also be used as a protective layer of a structure for impact resistance. According to Cook (1983), principally, expanded polystyrene concrete is used for prefabricated nonload bearing panels, hollow and solid block, lightweight sandwich panels and in highway construction as part of the sub-base where frost is harmful for sub grade stability. In building and construction, expanded polystyrene concrete almost can be used in any application where a combination of insulation and strength are required, such as roofs, cladding panels, curtain walls, ceiling, load-bearing concrete blocks, floating marine structures and sub-floor systems. In Australia, the primary use of polystyrene aggregate concrete has been the manufacture of non-structural components of concrete buildings including perimeter insulation, roof insulation, and masonry insulation. The structural use of is of much interest to engineers since it is envisaged that structural members made with polystyrene aggregate concrete would have certain advantages over those made

4 weight normal weight concrete (Lai, K.L., Ravindrarajah, R.S., Pasalich, W. and Hall, B., 1996), such as: (a) The lighter weight precast polystyrene aggregate concrete members would be easier to handle. (b) The formwork would need to withstand a lower pressure. (c) The size of the foundation can be reduced. (d) The lower thermal conductivity of polystyrene aggregate concrete would improve the fire rating of the building. (e) The better energy-absorbing capacity of polystyrene aggregate concrete would be beneficial in structures which are likely to be subject to dynamic or impact loading such as buildings in earthquake zones and buildings which store explosives. At the University of Technology, Sydney, significant research has been done in the development and properties of polystyrene aggregate concrete containing expanded polystyrene beads as well as waste polystyrene granules for over ten years and findings were reported elsewhere [10]. 4. ADVANTAGES & DISADVANTAGES OF POLYSTYRENE CONCRETE Advantages and disadvantages of the Polystyrene concrete (as established throughout this work). S.No. WORKS ADVANTAGES DISADVANTAGES 1. Weight Light; down to 900 kg/m3 2. Strength Ranging from 2 to 20 N/mm2 3. Resistance to chemicals Sensitive to most petroleum products 4. Field Applications Suitable for Structural and non-structural members Not suitable to be used as prestressed concrete 5. Cost Less than most available lightweight concretes 6. Acoustic resistance The best among all other lightweight concrete 7. Fire Resistance Burning without flames Starts to evaporate above C 8. Mix consistency Consistence for w/c 0.32 to 0.45 Stable up to 30 minutes after mixing 9. Thermal insulation The best among all other lightweight concrete 10. hardening time of fresh Less than normal concrete

5 concrete 5. CONCLUSION This paper has explored the characteristics of new lightweight concrete consisting of polystyrene, sand, cement and water. Through this paper it has been proven that the proposed mix is very reliable giving strengths of up to 200 kg/cm2 with a low density. The mechanical and chemical properties have, also, been discussed in order to study the behavior of polystyrene under different environments (i.e. field usage). The mix workability is very high at a very low water/cement ratio. REFERENCES [1] B. Chen, J. Liu, Experimental application of mineral admixtures in lightweight concrete with high strength and workability, Constr. Build. Mater. 22 (6) (2008) [2] N.U. Kockal, T. Ozturan, Strength and elastic properties of structural lightweight concretes, Mater. Des. 32 (4) (2011) [3] Osman Ünal, Tayfun Uygunog lu, Ahmet Yildiz, Investigation of properties of low-strength lightweight concrete for thermal insulation, Build. Environ. 42(2) (2007) [4] R. Demirboga, A. Kan, Thermal conductivity and shrinkage properties of modified waste polystyrene aggregate concretes, Constr. Build. Mater. 35 (2012) [5] J.M. Chia, R. Huang, C.C. Yangb, J.J. Changa, Effect of aggregate properties on the strength and stiffness of lightweight concrete, Cem. Concr. Compos. 25 (2) (2003) [6] Tommy Y. Lo, W.C. Tang, H.Z. Cui, The effects of aggregate properties on lightweight concrete, Build. Environ. 42 (8) (2007) [9] Short, A. & Kihnijburgh, W., 1978 [10] Malhotra, V.M., 1995 [11] Ravindrarajh, R.S.& Tuck, A.J., 1995 [12} Ravindrarajah, R.S., Difalco, V., and Surian, S., 2005