Polystyrene Lightweight Research Articles

Extrusion Foaming of Lightweight Polystyrene Composite Foams with Controllable Cellular Structure for Sound Absorption Application.

Polymer foams are promising for sound absorption applications. In order to process an industrial product, a series of polystyrene (PS) composite foams were prepared by continuous extrusion foaming assisted by supercritical CO2. Because the cell size and cell density were the key to determine the sound absorption coefficient at normal incidence, the bio-resource lignin was employed for the first time to control the cellular structure on basis of hetero-nucleation effect. The sound absorption range of the PS/lignin composite foams was corresponding to the cellular structure and lignin content. As a result, the maximum sound absorption coefficient at normal incidence was higher than 0.90. For a comparison, multiwall carbon nanotube (MWCNT) and micro graphite (mGr) particles were also used as the nucleation agent during the foaming process, respectively, which were more effective on the hetero-nucleation effect. The mechanical property and thermal stability of various foams were measured as well. Lignin showed a fire retardant effect in PS composite foam.

Behavior of Structural Lightweight Polystyrene Foam Concrete Flat Slabs When Exposed to Fire

Background: Reinforced concrete flat slab is used in a wide range of applications. In addition, reduction of the weight of the concrete used increases the advantages of the flat slab.

Wood plastic composites made from post-used polystyrene foam and agricultural waste

Ever since the development of lightweight polystyrene foam, the material has become an attractive single-use product packaging in various industries. Despite its high versatilities, post consumed polystyrene foam has very low rate of recycling due to the high cost during transportation and there is hardly any established economical recycling route. The purpose of this research is to investigate the potential of converting the polystyrene foam waste as raw material for producing wood plastic composite (WPC). In the present study, predefined formulation of recycled polystyrene (rPS), durian husk fiber (DHF) and processing aid Ultra-PlastTM WP516 were melt blended with the aid of Haake internal mixer. The homogenous mixtures were subsequently compression molded to form WPC. The effect of material compositions on tensile, thermal, and morphological properties of the rPS/DHF composite was highlighted. The results showed that tensile strength and modulus increase with fiber content, while elongation at break and thermal stability were decreased. With higher loading of Ultra-PlastTM WP516, both tensile and thermal properties decreased. This research found that WPC with optimum strength of 18.8 MPa can be produced from rPS having 60 parts per hundred resin (phr) of DHF and 0.5 phr of Ultra-PlastTM WP516, albeit the measured tensile strength is lower compared to commercial alternatives. The resulting WPC possess great potential in none high strength, structurally demanding application.

Testing and modeling the behavior of sandwich lightweight panels against wind and seismic loads

The behavior of non-structural sandwich lightweight panels against wind and seismic loadings is not well understood. Such panels are typically composed of two calcium-silicate board (CSB) wythes separated by a core infill made of expanded polystyrene lightweight concrete (LWC). This paper provides understanding regarding the mechanisms of panel connectivity by tongue-and-groove, including transfer of forces through steel dowels to the existing structure. Series of LWC mixtures having 470 to 975 kg/m3 density were tested using suitably established testing procedures to determine the flexural strength, core shear strength, interfacial bond between LWC and CSB, and pullout forces transmitted through the steel dowels. Special emphasis is placed on modeling the effect of wind and seismic loads on a 3.6 × 3 m2 partition wall constructed using LWC sandwich panels. The highest stresses and deformations generated from the model are compared to those determined experimentally, which allowed establishing different charts that can predict the safety factors as a function of LWC density and type/magnitude of the lateral loading applied.

Lightweight Self-Compacting Concrete Incorporating Perlite, Scoria, and Polystyrene Aggregates

Self-compacting concrete (SCC) is a highly fluid form of concrete that can consolidate under its own weight, thereby reducing the need of any mechanical compaction processes. Lightweight concrete (LWC), which incorporates the use of lightweight aggregates, can reduce the density of the concrete and therefore the potential associated dead loads. In recent decades, there have been numerous studies in the production of lightweight self-compacting concrete (LWSCC) that aim to combine the benefits of both SCC and LWC. Due to the various lightweight aggregates and their different material characteristics, it is imperative to assess whether the properties of both concretes still apply when using different lightweight aggregates. This paper aims to develop information about the fresh and hardened properties of lightweight self-compacting concrete using perlite, scoria, and polystyrene lightweight aggregates at varying replacement percentages. The fresh properties were investigated using the slump flow, T500, and J-ring tests. Hardened properties include 7- and 28-day compressive and tensile strengths, and compressive stress-strain behavior at 28 days.

Experimental investigation of low-angle dune morphodynamics

Dunes commonly dominate the bed of sandy rivers and they are of central importance in predicting flow resistance and water levels. In the present study, we show that by using light-weight polystyrene particles as substrate in a laboratory setting, promising morphodynamic similarity is obtained between dunes in shallow flow (flume) and deep flow (field) conditions. In particular, results from our flume experiments show that dune lee-side angles, which are crucial in turbulence production and energy dissipation, better approximate dune lee-side angles observed in natural channels. Furthermore, dune height evolution towards upper stage plane bed observed in the present experimental study, closely follows dune height evolution as observed in world’s large rivers.

Effect of matrix particle size on EPS lightweight concrete properties

Expanded polystyrene lightweight concrete is a composite which can be made by adding expanded polystyrene aggregate in normalweight concrete (as matrix). The research was focused on the effect of properties and volume of the matrix on the properties of lightweight concrete. The results show that properties of structural polystyrene concrete, such as workability and compressive strength, depend on the aggregate size of the matrix. It also shows that decreasing aggregate size of the matrix is the effective way to increase workability and compressive strength of lightweight concrete. When the density of concretes decrease by 200 kg/m³, slump values decrease by about 20 to 30 mm with lightweight concrete mixtures using maximum particle size of 0.63 mm, while slump values decrease by about 40 mm with the mixtures using maximum particle size of 20 mm. At the same density, the compressive strength of the structural polystyrenre concrete significantly decreased when the coarse aggregate diameter greater than 10 mm. Therefore, coarse aggregates with diameter size are smaller than 10 mm was recommended to use for matrix. In the result, expanded polystyrene concrete with density from 1,400 kg/m³ to 2,000 kg/m³ and compressive strength more than 20 MPa for structural application was made.

Geopolymer synthesis by the alkali-activation of blastfurnace steel slag and its fire-resistance

Geopolymer has been synthesized by the activation of blastfurnace steel slag (GGBFS) using 6% (NaOH) or 3% NaOH+3% Na2SiO3. The geopolymer obtained in both cases exhibits an amorphous homogeneous and tightly-packed structure as well as a high compressive strength exceeding, that obtained by conventional mortar. In testing the response toward elevated temperatures it has been found that the geopolymer formed using 3% NH+% NS as activator reveals high stability and fire resistance where it retains high strength values even upon exposure to temperatures up to 500°C. The results clarify, also, that the geopolymer possesses stability and fire resistance higher than those exerted by normal concrete. The current study indicated the feasibility of the alkali – activated BFS geopolymer as a fire resistant coat substituting the reinforced concrete coat to lightweight polystyrene panels used for walls, roofs and partitions in construction work. Such introduced coat offers the following merits relative to the reinforced concrete coat: lower density, higher strength, higher fire-resistance, free of steel mesh reinforcement and reduced cost. The results of the present investigation clarify that geopolymerization could be considered as a viable technology for the conversion of industrial by-products having an aluminosilicate composition into attractive construction materials.

Application of light-weight filtration media in an anoxic biofilter for nitrate removal from micro-polluted surface water.

The research investigated nitrate removal from micro-polluted surface water by the single-stage process of anoxic biofilter using light-weight polystyrene beads as filtration media. In this study, sodium acetate was used as an external carbon source and the nitrate removal efficiency under different regimes of hydraulic loading rate (HLR), water temperature, and C/N ratio was studied. In addition, the effect of backwash on denitrification efficiency was investigated. The results show that the biofilter achieved a high nitrate removal efficiency in 2 weeks at water temperatures ranging between 22 and 25 °C at a C/N ratio (COD:NO3(-)-N) of 6:1. Besides, the average removal efficiency of nitrate at HLRs of 5.66, 7.07 and 8.49 m(3) m(-2) h(-1) were 87.5, 87.3 and 87.1%, respectively. The average removal efficiency of nitrate nitrogen was 13.9% at a HLR of 5.66 m(3) m(-2) h(-1) at water temperatures of 12-14 °C, then it increased to 93.7% when the C/N ratio increased to 10. It suggests that the optimal hydraulic retention time is at water temperatures of 8-10 °C. The water consumption rate of backwash was about 0.2-0.3%, and denitrification efficiency returned to the normal level in 12 h after backwash.

Optimization of Expanded Polystyrene Lightweight Aggregate in Pre-Cast Concrete Blocks by a Completely Random Experimental Design (CRED) with Mixture and Process Variables

The aim of this study was to determine the optimum design mix to produce pre-cast concrete blocks by a completely random experimental design (CRED) with mixture and process variables. The polymerized concrete was studied its composition: Cement, and water defined as the mixture compounds. To choose the best model, all the possible models were assessed through the ANOVA, which tested each possible model. The linear-linear model was preferred, since that do not present evidence of lack of fit, and it is capable of relating how to react the process variables, when are changed the variable mixture condition levels. The optimum experimental condition, obtained for the polymerized concrete, was: The size of the polystyrene beads was 4.8 mm sized polystyrene beads, 5.0% polystyrene that replaced the aggregate, 18.3% cement, 73.4% aggregate and 8.3% water. In this condition, the blocks made with polymerized concrete show a compressive strength above 15 Mpa, allowing its utilization in paving.

Prediction of compressive strength and elastic modulus of expanded polystyrene lightweight concrete

Expanded polystyrene (EPS) lightweight concrete is composed of a plain concrete matrix and EPS beads. The aim of the study was to characterise the mechanical properties of EPS lightweight concretes containing various volumes of EPS (0%, 5%, 10%, 15%, 20%, 25%, 30%, 35% and 40%) and of two water/cement ratios (0·45 and 0·55). The test results indicate that the apparent density, compressive strength, splitting tensile strength and elastic modulus of EPS concrete decrease when the content of EPS particles increases. Based on the experimental results and composite approach, a new simplified mathematical model is proposed for evaluating the compressive strength and elastic modulus of EPS concrete as a function of the mechanical properties of the plain concrete, the mechanical properties of the EPS and the percentage of EPS particles.

Live-Bed Scour at Bridge Piers in a Lightweight Polystyrene Bed

AbstractExperiments on scour at bridge piers were carried out in a sediment recirculating flume with a bed of polystyrene particles. The focus of the research reported in this paper was given to live-bed experiments. All experiments were run until equilibrium conditions with flow velocities u ranging from 0.8–8.5 times the critical velocity for the incipient motion of sediment particles uc. Maximum scour depth was continuously measured with an endoscopic camera from inside the pier, which was constructed by a plexiglass cylinder. Bed load transport with dunes was identified as the main transport mode for 1<u/uc<4. For ratios of u/uc≥4 entrainment into suspension without development of bedforms dominated. Results show that scour rapidly reach equilibrium in the bed of polystyrene pellets. In the clear-water experiments equilibrium scour depth remained constant in time. In the bed load region the fluctuation of scour depth corresponded to the dune migration through the scour hole, while in the suspended loa...

Shear behavior of light weight ferrocement concrete slabs

The objective of the work presented in this research was to develop light weight composite slab subjected to punching load by using column slab connection at the center of the slab which comprises polystyrene block of thickness 80 mm reinforced with welded galvanized steel mesh or expanded steel mesh. The use of expanded metal mesh and welded steel mesh was proposed as a viable alternative to ordinary steel bars in reinforcing ferrocement plates, also it was proposed to use it with ordinary steel bars to enhance the mechanical behavior of the composite slab. For light weight sandwich elements, light weight polystyrene of density 12Kg/m3 is used as a core material and welded wire meshes or expanded steel meshes are to be used as steel reinforcement at the two thin skin layers. Twelve squares composite light weight slabs were developed having the dimensions of 1200mm x 1200mm and overall thickness of 140mm were tested simply supported along all four sides under central column slab connection until failure. This research presents the behavior of ferrocement lightweight slabs under punching shear. The effects of various types of reinforcing materials were investigated. Using such lightweight materials will contribute to decreasing the weight of the elements and consequently decreasing the overall dead load of the building. Moreover, the study aimed at improving some other characteristics like flexural strength, crack pattern, first crack load, crack width, and deflection.

Preparation and Study on the Waterproof Performance of Polystyrene Lightweight Composite Insulation Materials

In the experiment, polystyrene particles were used as lightweight aggregate to prepare lightweight composite insulation board which was mixed with fibers and waterproofing agent. The effect of water-cement ratio and volume ratio of polystyrene particles and cement on the density and mechanical properties of polystyrene insulation board was researched. And styrene-acrylic emulsion, stearic acid emulsion and composite emulsion waterproofing agent were used respectively to modify the waterproof of insulation board. Besides, the underlying action mechanism was explored. The results show that the optimum volume ratio was 5:1, and the optimum water-cement ratio was 0.45. And when the content of composite emulsion waterproofing agent was 8%, the 2h and 24h water absorption were 6.0% and 8.1% respectively.

River scale model of a training dam using lightweight granulates

Replacing existing river groynes with longitudinal training dams is considered as a promising flood mitigation measure in the main Dutch rivers, which can also serve to guarantee navigability during low flows and to create conditions favourable for ecological development. Whereas the bed response in the streamwise uniform part of a river trained by a longitudinal dam can be readily predicted, the bed response at the transition zones is unclear. In the present study, we investigate the local morphological effects resulting at the intake section of a longitudinal training dam, where the flow is distributed over the main channel and a side channel in between the dam and the river shore. A sediment recirculating model with a nearly undistorted geometry with respect to the prototype was setup. Lightweight polystyrene granulates were used as a surrogate for sediment, to properly scale the Shields parameter without compromising Froude scaling, and reach dynamical similarity. A laser scanner allowed collecting high-resolution bed elevation data. Results obtained under typical low flow and high flow conditions show a general deepening of the bed in the area adjacent to the training dam, in response to narrowing of the main channel. Scour at an upstream river groyne embedded in the model showed a scour hole which was deeper than realistic. Throughout the entire domain, bedforms developed featuring geometrical properties that reproduced the prototype conditions appropriately. Based on a comparison with characteristics from the River Waal, regarded as the prototype without a longitudinal dam, lightweight sediments were considered to be a proper choice for this study, in which bedload is the main sediment transport mode. The main conclusion regards the absence of significant morphodynamic developments at the intake section, both during the high flow experiment and during the low flow experiment, which can be attributed to the alignment of the dam with the local streamlines.

Researches Concerning Structural and Mechanical Behavior of Sandwich Composite Polymeric Products

The sandwich composite polymeric products have a wide utilization in various fileds like aircraft and automotive construction, load bearing structures, sports equipment, more specifically, wherever weight-saving is required. Sandwich composites polymeric products represent excellent examples of the potential offered by composite materials. The combination of two composite faces and a lightweight polystyrene core allows obtaining a high flexural stiffness with a weak mass. This paper deals with the analysis of the structural and mechanical behavior properties of the core, adhesive and faces, for sandwich composite polymeric products. There are also presented the investigation results on how different specific factors like: mechanical and structural behavior, interface between the faces and core, constant force resistance in time, the reinforcing elements (fiber glass), the polyester core do influence the machinability of sandwich composites polymeric products..

Comparing Lightweight Polystyrene Concrete Using Engineered or Waste Materials

This paper investigates the difference between using manufactured or waste-expanded polystyrene (EPS) as an aggregate replacement in concrete. Concrete mixture proportions are held constant, whereas two types of EPS—reground waste material (RGD) and manufactured spherical bead (BD)—replace a portion of the fine aggregate. The plastic state and hardened state properties are quantified and compared between test batches and the plastic state measures of consistency, air content, and unit weight are reported in this paper. The measures hardened state properties include compressive strength, elastic modulus, strength-weight ratio, and energy-related toughness as determined using compression load-deflection curves. The results indicate that, for comparable concrete mixtures, BD mixtures exhibited improved workability and reduced air entrapment or entrained air as compared to RGD mixtures due to differences in EPS particle surface characteristics. Furthermore, statistically significant increases in compressive strength and energy-related toughness are demonstrated for BD mixtures in comparison to RGD mixtures.

Mechanical properties of expanded polystyrene lightweight aggregate concrete and brick

In this study, mix proportion parameters of expanded polystyrene (EPS) lightweight aggregate concrete are analyzed by using Taguchi’s approach. The density, compressive strength and stress–strain behavior were tested. The optimal mixture of EPS lightweight aggregate concrete was selected among experiments under consideration to manufacture the lightweight hollow bricks. The results show that EPS dosage has the most significant effect on compressive strength of EPS lightweight aggregate concrete, then water and cement ratio, while the content of cement and sand ratio play a comparatively less important part. The relationship between density and compressive strength of EPS lightweight aggregate concrete is proposed as f c = 2.43 × γ 2.997 × 10 −9. The legitimacy of the use of EPS lightweight bricks made by EPS lightweight aggregate concrete is confirmed.

Flexural strengthening of reinforced lightweight polystyrene aggregate concrete beams with near-surface mounted GFRP bars

Application of near-surface mounted (NSM) fibre reinforced polymer (FRP) bars is emerging as a promising technology for increasing flexural and shear strength of deficient reinforced concrete (RC) members. In order for this technique to perform effectively, the structural behaviour of RC elements strengthened with NSM FRP bars needs to be fully characterized. This paper focuses on the characterization of flexural behaviour of RC members strengthened with NSM glass-FRP bars. Totally, 10 beams were tested using symmetrical two-point loads test. The parameters examined under the beam tests were type of concretes (lightweight polystyrene aggregate concrete and normal concrete), type of reinforcing bars (GFRP and steel), and type of adhesives. Flexural performance of the tested beams including modes of failure, moment–deflection response and ultimate moment capacity are presented and discussed in this paper. Results of this investigation showed that beams with NSM GFRP bars showed a reduction in ultimate deflection and an improvement in flexural stiffness and bending capacity, depending on the PA content of the beams. In general, beams strengthened with NSM GFRP bars overall showed a significant increase in ultimate moment ranging from 23% to 53% over the corresponding beams without NSM GFRP bars. The influence of epoxy type was found conspicuously dominated the moment–deflection response up to the peak moment. Besides, the ultimate moment of concrete beams reinforced with GFRP bars could be predicted satisfactorily using the equation provided in ACI 318-95 Building Code.

A repetitive movement detector used for automatic monitoring and quantification of scratching in mice

We have designed an economical non-invasive movement detector for small animal studies and used it for monitoring and quantifying itch in mice. The system is based on a sensitive force transducer positioned below a recording platform holding a lightweight polystyrene recording box in which an animal is placed. A programmed micro-controller is used to discriminate between non-specific movement, grooming behaviour, and scratching movements made by the animal's hind limb. Following sub-dermal injection of histamine receptor agonists into the neck of a mouse, dose-related scratching occurred which was detected and quantified. There was 91% correlation between bouts of scratching as counted manually from playback of the video recording and recorded by the detector. The detector was also able rapidly to count the individual scratch movements of the hind limb that comprise a bout, with 95% accuracy in comparison with manual counting during slow motion playback of video tape, something that is impossible for an unaided observer to achieve because individual scratch movements are too fast to discriminate by eye. Separate detectors were used for the efficient non-invasive study of four animals simultaneously, and this number could easily be increased by adding more platforms. The system could also be modified to record the animal's position within the box, which would be of value in studies involving exploratory behaviour. In summary, the non-invasive multichannel repetitive movement detector will be very useful for accurate measurement of scratching during pruritus studies in small animals, with considerable savings in staff time and effort. It should therefore be a valuable tool for helping to investigate pruritus and in the evaluation of anti-pruritic drugs.