Polystyrene Aggregate Research Articles

Experimental investigations on ultra-lightweight-concrete encased cold-formed steel structures: Part II: Stability behaviour of elements subjected to compression

In the field of structural engineering the design of cost efficient structures is highly important. This led to the development of cold-formed steel structures (CFS). An advanced CFS structure is introduced in this paper, which uses a special type of polystyrene aggregate concrete (PAC) as bracing material. This material has beneficial insulating and fire protection properties, which makes it a reasonable choice for residential buildings. An experimental programme was performed, to gain information on the flexural and axial behaviour of PAC-encased CFS elements and panels. Both unbraced and braced members were tested to gain information on increment of load-bearing capacity. Several different element sizes were used to be able to investigate the different stability failure modes (i.e. local, distortional and global). Results showed that PAC was able to restrain the global and distortional buckling modes of steel elements, thus providing “full bracing” in most practical cases. These results are introduced in two papers (Part I and II), detailing the failure modes, load increments and the effect of composite action. In this paper – Part II – the background and the results of compression tests are presented, and the bending experiments are detailed in Part I [1].

Experimental study on ultra-lightweight-concrete encased cold-formed steel structures Part I: Stability behaviour of elements subjected to bending

In the field of structural engineering the design of cost efficient structures is highly important. This led to the development of cold-formed steel structures (CFS). An advanced CFS structure is introduced in this paper, which uses a special type of polystyrene aggregate concrete (PAC) as bracing material. This material has beneficial insulating and fire protection properties, which makes it a reasonable choice for residential buildings. An experimental program was performed, to gain information on the flexural and axial behaviour of PAC-braced CFS elements and panels. Both unbraced and braced members were tested to gain information on increment of load-bearing capacity. Several different element sizes were used to be able to investigate the different stability failure modes (i.e. local, distortional and global). Results showed that PAC was able to restrain the global and distortional buckling modes of steel elements, thus providing “full bracing” in most practical cases. These results are introduced in two papers (Part I and II), detailing the failure modes, load increments and the effect of composite action. In this paper – Part I – the background and the results of bending tests are presented, and the experiments on the compression elements are detailed in Part II [1].

Advanced Hygrothermal Performance of Building Component at Reconstruction of S. Radonezhskiy Temple in Volgograd

The paper presents new thermal design of external wall S. Radonezhskiy temple in Volgograd is developed according to author’s concept. The three-layer brick wall, including a thermal insulation layer from concrete with polystyrene aggregates, is considered. Calculation of interstitial condensation in building component is carried out according to simplified calculation method developed by the author and harmonized to ISO 13788. Analysis of calculation results shows that condensation occurs at one interface during some months but there is no accumulation over the year as all the condensate is predicted to evaporate again. Thus, there is no systematic moisture accumulation at the building component within a year. The risk of run-off from non-absorbent materials will be very low. Analysis of the evaporation rates at the interface shows that duration of drying wetted layer in external wall during initial stage does not exceed admissible values.

Structural behaviour of reinforced concrete beams containing a novel lightweight aggregate

This paper reports the results of an experimental investigation into the structural behaviour of reinforced concrete beams incorporating a novel EPS-based lightweight aggregate (LWA) called stabilised polystyrene (SPS) aggregate. Four concrete mixtures with water to cement (W/C) ratio of 0.8 were used. The replacement levels of natural aggregate by SPS were 0%, 30%, 60% and 100%. The volume ratio to manufacture SPS aggregate was 8:1:1 (80% waste EPS: 10% cement: 10% clay). A total of 24 beams were cast and tested at 28-day age. Three types of tension reinforcement were used: 2 bars, 3 bars and 2 bars + shear links. There were no compression bars at the top for all beams. Four point-loading flexural tests were conducted up to failure. In general, it can be observed that the structural behaviour of SPS concrete beams is similar to that of other types of lightweight aggregate concretes used around the world.

Evaluation of Shear Strength Properties of Modified Expanded Polystyrene Aggregate

The paper presents the results of series of direct shear tests made on recycled waste expanded polystyrene foams (EPS). Waste EPS were thermally modified in an oven at 130 ̊C through 15minutes and crushed into aggregate size before tested. Heat treatment of the EPS increased its density from 15kg/m3 to nearly 200kg/m3. Shear strength behavior of modified EPS were investigated in loose and dense states under three different normal stresses. The test results showed that shear strength behavior of modified EPS is similar to that of sand. Internal friction angle of modified waste EPS in the dense state is higher than of loose state.

Direct detection of aggregates in highly turbid colloidal suspensions of polystyrene nanoparticles.

We demonstrate a total internal reflection-based method that detects, for the first time to the best of our knowledge, directly without any sample dilution or special sample preparation, the presence of aggregates in highly turbid aqueous suspensions of polystyrene nanospheres. Aggregation is induced by changing either the sample pH or ionic strength. The polystyrene mass density in our samples is two orders of magnitude higher than previously reported polystyrene aggregation studies. In cases when aggregates have formed but do not yet occupy a significant fraction of the sample volume, our sensor outperforms state of the art techniques such as dynamic light scattering in terms of sensitivity. Conversely, when the sample volume is dominated by aggregates, our sensor is not as effective.

Briefing: Shear strength of concrete with E-waste plastic

This briefing paper presents results from an experimental investigation on the shear strength of concrete with E-waste plastic (high-impact polystyrene) as coarse aggregate. The coarse aggregate is partially replaced with different percentages of high-impact polystyrene by volume (10, 20, 30, 40 and 50%). It is found that the shear strength is decreased with the increase of high-impact polystyrene in concrete. Even though a reduction in strength is observed, however, the high-impact polystyrene aggregate alters the brittle behaviour of concrete into ductile behaviour. At 50% replacement, 50% of strength retention in the concrete is observed. Therefore, high-impact polystyrene aggregate can be used as a partial replacement for coarse aggregate up to a certain percentage; this represents one possible solution to the E-waste problem and an alternative to using natural aggregate.

Creep and creep recovery properties of polystyrene aggregate concrete

The present study aims to characterize the creep behaviour of Polystyrene Aggregate Concrete (PAC). The creep and creep recovery of PAC were determined experimentally and compared with normal weight concrete. The parameters studied include polystyrene aggregate (PA) content, curing and storage conditions. The ultimate creep strains for the polystyrene aggregate concrete were estimated using a hyperbolic expression and compared to the other common prediction models for normal weight concrete. The experimental results showed that creep of polystyrene aggregate concrete increased with the increase of PA content in the mix. The ratios of creep recovery to creep strains decreased slightly with an increase in PA content. The curing and storage conditions showed remarkable influences on the creep of PAC, but not for its creep recovery. Besides, the creep prediction results were compared against the prediction models given by ACI and CEB-FIP.

Strength and durability assessment of self-compacted lightweight concrete containing expanded polystyrene

This paper presents the effect of expanded polystyrene (EPS) aggregate on the strength and durability of self-compacted lightweight concrete (SCLC). SCLC mixes with different water/binder ratios and EPS contents (10, 15, 22.5 and 30 % by volume) were cured in two different curing regimes. Durability properties were investigated by water absorption, electrical resistivity, air permeability and chloride penetration profiles. Results showed that EPS mixes cured in salt/wetting regime mostly show higher levels of compressive strength. SCLC with EPS mostly has a low absorption categorized as “good” concrete quality. After 90 days, mixtures with density higher than 2,000 kg/m3 have low corrosion risk. In these mixtures, corrosion did not really pass the threshold of activity at 2.5 cm covering depth. In addition, air exclusion ratio was observed to be lower for EPS mixes with lower W/B ratio.

Properties of lightweight concrete composed of magnesia phosphate cement and expanded polystyrene aggregates

Expanded polystyrene (EPS) concrete is a lightweight concrete with better deformation capacity, but lower strength than conventional concrete. Its application for structural components was limited due to inadequate strength. The present study aims to develop a class of structural grade EPS concrete by replacing Portland cement with magnesia phosphate cement (MPC). The resulting MPC–EPS concrete had a density ranging from 750 to 1,800 kg/m3. Extensive laboratory tests were performed to characterize the strength, drying shrinkage and water absorption properties of the MPC–EPS concrete. The test results showed that the MPC–EPS concrete had a higher early-age strength than the typical EPS concrete, and the rate of strength gain increased with increasing EPS contents. The drying shrinkage potential and water absorption of the MPC–EPS concrete were much lower than those of the typical EPS concrete, indicating that the MPC–EPS concrete could be a building material with high thermal-resistance and good durability.

Characteristic Behaviors in Compressive Strength of Two-Dimensional Aggregates

A selected material, polystyrene microsphere series, is created as a building block of two-dimensional (2D) aggregates to examine scaling behaviors of the compressive stress condition. The 2D aggregated clusters are confined between the two cantilevers of 30 micron in diameter. These cantilevers can slide and force the aggregates move in the lateral direction. The compressive yield stress is directly measured during experiments by quantitative image analysis on the optical microscope. Locations of polystyrene aggregates are traced by Discrete Element Method (DEM), computer simulation. The 2D mechanical properties are examined for the particle size scaling behaviors as a function of particle area fraction and the average particle coordination number. The larger the particle size, the greater the modulus and the yield stress.

Concrete and Structure with Recycled Aggregate

In recent years, importance and necessity of using the recycled aggregate are recognized because of the depletion of quality primary aggregates and greater awareness of environmental protection. It is now widely accepted that there is a significant potential for reclaiming and recycling demolished debris for use in value added applications to maximize economic and environmental benefits. There is increasing demand and interest in aggregates from nontraditional sources such as from industrial byproducts and recycled construction and demolition wastes. The purpose of this special issue is to summarize the various researches on concrete and structure with recycled aggregate. A few papers invited in this special issue give their contribution to advance research in this field. The first paper of this special issue presents the cellular concrete bricks obtained by using a lightweight mortar with recycled expanded polystyrene aggregate instead of sandy materials. This type of concrete bricks is lighter and more flexible, which makes it less vulnerable to cracking walls due to soil displacements. The developed bricks have good mechanical properties and flexural strength and less permeable. The second paper deals with the cementing potential of pulverized oyster shell, rich in calcium, when mixed with fly ash and soil. Authors indicate that more the pulverized oyster shell adds, lower the strength will get both in the soil and lime specimen. The soil specimens containing fly ash gradually gain strength as curing proceeds. The third paper shows that the impact properties of the recycled aggregate concrete exhibit strong strain-rate dependency and increase the increase of peak strain-rate. The transition point from low strain-rate sensitivity to high sensitivity decreases with the increase of matrix strength. Authors indicate that the energy absorption capacity of recycled aggregate concretes specimens is lower than that of natural aggregate concretes. The fourth paper presents an optimization of the mixing proportion of recycled aggregate concrete by using neural networks based on genetic algorithms. This method will contribute to improve the usage of the recycled aggregate in the construction industry and to reduce the waste in the construction process. In the fifth paper, the effects of ground waste concrete powder coming from the attached paste/mortar on water demand for normal consistency, setting time, fluidity, and compressive strength of cement were analyzed. The last paper presents the fire resistance and the relevant thermal properties of high-performance concrete (HPC) with fly ash. The effect of temperature from 200 to 500C on compressive strength, cubic compressive strength, cleavage strength, flexural strength, and the ultrasonic velocity of the high-performance concrete with fly ash was studied.

Cellular Concrete Bricks with Recycled Expanded Polystyrene Aggregate

Cellular concrete bricks were obtained by using a lightweight mortar with recycled expanded polystyrene aggregate instead of sandy materials. After determining the block properties (absorption, compressive strength, and tensile stresses), it was found that this brick meets the requirements of the masonry standards used in Mexico. The obtained material is lighter than the commercial ones, which facilitates their rapid elaboration, quality control, and transportation. It is less permeable, which helps prevent moisture formation retaining its strength due to the greater adherence shown with dry polystyrene. It was more flexible, which makes it less vulnerable to cracking walls due to soil displacements. Furthermore, it is economical, because it uses recyclable material and has properties that prevent deterioration increasing its useful life. We recommend the use of the fully dry EP under a dry environment to obtain the best properties of brick.

Effects of nanopolystyrene on the feeding behavior of the blue mussel (Mytilus edulis L.)

As the industrial production of nanoplastic and the degradation of microplastic into smaller particles at sea increase, the potential amount of nanoplastics in the marine environment rises. It has been reported that mussels uptake 100-nm polystyrene (PS) beads; to date, however, the effects of this uptake on the organism are unknown. In the present study, the authors investigated the effects of 30-nm PS on the feeding behavior of the blue mussel (Mytilus edulis) by exposing the organism to different nano PS and different algae (Pavlova lutheri) concentrations. The state of nano PS aggregation in the exposure medium was assessed using dynamic light scattering. In all treatments that contained nano PS, M. edulis produced pseudofeces. The total weight of the feces and pseudofeces increased with increasing nano PS and increasing algae concentration. Furthermore, M. edulis reduced its filtering activity when nano PS was present but still caused a decrease in the apparent nano PS concentration in the water. The presence of nano PS around the foot of M. edulis after the bioassay confirmed that the organism removed nano PS from the water. Chronic effect studies are therefore needed to investigate the effects of nanoplastics in M. edulis and possible consequences for its predators, including humans.

Thermal conductivity and shrinkage properties of modified waste polystyrene aggregate concretes

Using artificial aggregate in replacement of natural aggregate in production of concrete has a tendency to increase by the future in order to provide greater sustainability in construction industry. This study investigates the effectiveness of thermal modified waste expanded polystyrene (MEPS) on the workability, density, thermal conductivity and shrinkage of concrete. MEPS aggregate was used as lightweight aggregate in concrete by 25%, 50%, 75%, and 100% in replacement of natural aggregate. The thermal conductivity of samples decreased with increasing of MEPS aggregate and their values were 1.990, 1.518, 1.000, and 0.600W/mK for 25%, 50%, 75%, and 100% MEPS aggregate in replacement of natural aggregate, respectively. Maximum reduction in the thermal conductivity was observed at the samples that made up of 100% MEPS aggregates and the reduction percentage was around 70%. The average drying shrinkage after 210-day of ambient curing condition was 2.59×10−3 for samples of 25% natural aggregate, while it was 5.08×10−3 for 100% MEPS aggregate samples.

Preliminary Evaluation of Septic‐System Absorption‐Field Architecture Types in a Profile‐Limited Soil

Managing household wastewater is an issue that affects hundreds of thousands of people in rural communities nationwide, many of whom rely on septic systems as their primary means of household wastewater disposal. Septic system absorption field products with architectures quite different from traditional pipe-and-gravel systems are being installed in many states with variances from initial design specifications. The objective of this study was to evaluate the performance, as measured by the in-product height of stored solution, of four differing absorption-field product architecture types in a profile-limited soil that was loaded at the maximum allowable rate based on soil morphology. Five chamber, two gravel-less pipe, two polystyrene aggregate, and four pipe-and-gravel systems were installed in a profile-limited, Captina silt loam soil (fine-silty, siliceous, active, mesic Typic Fragiudult) and dosed with raw effluent at rates determined by current State of Arkansas regulations via individual peristaltic pumps. Free-solution monitoring ports were installed within each product, where the depth to free solution was measured periodically and used to evaluate product performance. Data collected from January through August 2009 indicated that preliminary system performance was unaffected by product architecture type. All products performed similarly under dry soil conditions. However, differences among individual products were observed during periods of hydrologic stress (i.e., wet soil conditions). Surfacing of effluent was not observed atop any product, indicating that the current loading rate design method is functioning properly. Preliminary results indicate that some alternative absorption-field products perform similarly to the traditional pipe-and-gravel system, thus providing flexibility and options for homeowners.

Properties of Low-Density Lightweight Aggregate Concrete under Uniaxial Loading

The aim of this study is to investigate the influence of EPS content on failure mode, stress-strain relationship and elastic modulus of expanded polystyrene aggregate concrete (PAC) with density lower than 900 kg/m3under uniaxial loading. The results show that PAC performs a good compressibility in the compression failure process. Apparent oblique crack appears in the case of uniaxial compression specimen damage; the lower the density is, the smaller the tilt angle of oblique cracks will be. Stress-strain curve of PAC with density larger than 422 kg/m3maintains a straight line relationship on ascending segment but varies with the density on the descent segment. The lower the density is, the larger PAC residual relative stress will become. Elastic modulus of PAC is proportional to 5.85 times index of relative density.

Mechanical properties of EPS lightweight concrete

The aim of this study was to investigate the effects of expanded polystyrene aggregate size, matrix strength and polypropylene fibre addition on the strength of lightweight concrete. Three types of expanded polystyrene beads with 1·0, 2·5 and 6·3 mm diameter were added to a high-strength matrix to produce lightweight concrete. Fine silica fume and polypropylene fibres were used to improve material properties. Lightweight expanded polystyrene concretes with different matrix strengths were investigated for compressive and splitting tensile strength. The expanded polystyrene concrete with small expanded polystyrene beads showed higher compressive strengths and the increase was more pronounced in low-density concrete than high-density concrete. The matrix strength was also observed to affect the particle size effect of expanded polystyrene beads on the compressive strength of concrete. The increase in compressive strength with the decrease of expanded polystyrene bead size was more pronounced in the low-strength matrix. In addition, polypropylene fibres significantly improved the strength of expanded polystyrene concrete, with the 28-day compressive and splitting tensile strengths of expanded polystyrene concrete being up to 43 and 44% higher than those of reference concrete.

Fracture Properties of Concrete Containing Expanded Polystyrene Aggregate Replacement

Research has shown that expanded polystyrene (EPS) aggregate replacement changes the failure mode of concrete in compression by exhibiting a more ductile dissipation of load during failure. Fracture mechanics are applied in this report to study the behavior of concrete containing EPS aggregate that replaces a volume portion of the normal weight fine aggregate. The fracture energy, critical stress intensity factor, and characteristic length of EPS concrete and normal weight concrete (NWC) is experimentally determined. The two types of tests used to determine these properties are the three-point-bend test and a wedge-splitting test. The conclusions demonstrate that EPS aggregate replacement increases fracture surface areas and the size of the fracture process zone, thus creating a more dispersed cracking pattern. The resulting failure mode allows the concrete to absorb more energy and maintain load after reaching peak load.Research has shown that expanded polystyrene (EPS) aggregate replacement changes the failure mode of concrete in compression by exhibiting a more ductile dissipation of load during failure. Fracture mechanics are applied in this report to study the behavior of concrete containing EPS aggregate that replaces a volume portion of the normal weight fine aggregate. The fracture energy, critical stress intensity factor, and characteristic length of EPS concrete and normal weight concrete (NWC) is experimentally determined. The two types of tests used to determine these properties are the three-point-bend test and a wedge-splitting test. The conclusions demonstrate that EPS aggregate replacement increases fracture surface areas and the size of the fracture process zone, thus creating a more dispersed cracking pattern. The resulting failure mode allows the concrete to absorb more energy and maintain load after reaching peak load.

Compact interferometric optical tweezer for patterned trapping and manipulation of polystyrene spheres and SWCNTs

We demonstrate a simple and compact optical interferometric unit combined with a conventional optical tweezer system for simultaneous multiple trapping and micromanipulation of mono-dispersed polystyrene spheres and aggregation of small-floating clusters of single-walled carbon nanotubes (SWCNTs). The interferometric unit was made compact by means of coating a thin layer of aluminum oxide on one side of the cubic beam splitter (CBS) which works as a static reference mirror and an adjustable mirror was mounted on a XYZ translational stage facing the other adjacent side of the CBS. Thus, the developed interferometric unit is quite analogous to a Michelson interferometer but is compact. Sinusoidal interference fringes with variable carrier frequency and orientations were generated. The interference fringes were then used for multiple trapping of polystyrene spheres along bright fringes resulting in pattern formation and also the aggregation of tiny floating clusters of SWCNTs. The proposed system is compact and easy to align because of its common-path geometry.