Polystyrene Properties And Uses Pdf
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Mass production of tires and their subsequent storage after use are serious environmental problems that are being tried to be solved in various ways. One of these is the mixture of these old used tires [ground rubber tire GTR ] with various thermoplastic and thermostable polymers. The present work aimed to obtain materials suitable for the electric industry from the mixture of polystyrene PS with old used tires GTR , starting from the requirement of minimum recycling costs, i.
Production and characterization of the mechanical and thermal properties of expanded polystyrene with recycled material 1.
Polystyrene PS is a clear, amorphous, nonpolar commodity thermoplastic that is easy to process and that can be easily converted into a large number of semi-finished products like foams, films, and sheets. It is one of the largest volume commodity plastic, comprising approximately seven percent of the total thermoplastic market 1. PS is a very good electrical insulator, has excellent optical clarity due to the lack of crystallinity, and has good chemical resistance to diluted acids and bases. It is also easy to fabricate into a large number of finished goods since it is a viscous liquid above its glass transition temperature T g that can be easily molded. However, polystyrene has several limitations.
This work studied the properties of lightweight concretes with addition of expanded polystyrene EPS for structural walls applications. EPS for being a material produced on a large scale and has low density, produces a large volume of waste.
These residues are not reused, especially in Brazil. Given that, in order to perform a comparison of the performance of concrete with adding of EPS in pearls and recycled, it have been manufactured five concrete types, a control without addition of EPS and four other samples with two different percentages of EPS. The mechanical compressive strength and physical density, voids content, absorption by immersion and capillarity properties were evaluated, and tests were carried out to evaluate the thermal performance of the mixtures studied.
The concretes with EPS presented compressive strength less than the reference concrete, however, the absorption for capillarity and thermal properties was better in concretes with EPS. Usually, the lightweight concrete designation is used to identify concretes with porous structure, generally based on hydraulic binders, with density lower than traditional concrete, that can be obtained with the use of lightweight aggregates, with the incorporation of air cellular concrete or without filler [ 1 ].
In addition to the technical and economic issues, the choice of building materials is also based on the environmental aspects of the implementation and use of the materials, in this sense, the lightweight concrete can provide, in its lower density, decreased reinforcement, energy used in transportation and in the constructive process. Due to its ability to heat insulation, it lowers energy consumption in thermal conditioning of buildings, when used in external seals [ 2 ].
Yet on this environmental issue, industrialized materials mobilize vast financial resources, consume a huge amount of energy, generate great amounts of waste that in large majority are not reused, causing permanent pollution, besides to the consumption of non-renewable raw materials. According to Leite [ 3 ], there are many sources that generate waste in construction.
For example, the waste of materials that could be reused in construction, but instead, leave the site in form of rubble that contribute in the volume of waste generated. Hence the importance of researching for new materials to manufacture concrete from unconventional methods, mostly recyclable. Expanded polystyrene EPS , can fit between these new materials to replace the aggregate in the concrete, in addition to the traditional materials: cement, natural aggregates and water, may contain additives and other additions, including fibers.
According to Monteiro [ 4 ], in Brazil were produced tons of EPS in the year and other tons were imported with electronic equipment and different goods brought from abroad. In were produced in Brazil about to tons of expanded polystyrene EPS and about tons of Extruded Polystyrene XPS , a thermal insulator normally presented in light and rigid boards, totaling about tons.
Of this total, it is estimated that approximately tons were returned to the productive process of recycling, that is, only 8. Estimates indicate that the EPS takes about hundreds of years to be completely degraded. There are studies with the use of EPS in the form of beads, as aggregate for lightweight concrete.
In experiments done by Parant and Le Roy [ 5 ], to formulate and optimize concretes with expanded polystyrene, the density and the structural strength were changed. The results showed that the compressive strength of concrete with EPS increases with the decrease in the size of the EPS beads for a same density. However, EPS can also be reused from waste disposed of, reducing the environmental impact of disposing of this polymer of hard decomposition and even improving the properties of new materials or modified like the lightweight concrete, for example.
The aim of this paper it was to produce mixtures of concrete with EPS beads and recycled EPS particles in order to assess and compare their properties for application in structural walls of buildings. Mechanical, physical properties were evaluated.
Small cubicles were also built with EPS concrete slabs containing different amount of EPS to evaluate the effectiveness of the EPS addition in controlling the heat flow and internal temperature. In accordance to the objectives proposed in this research, the methodology was implemented based on experimental program, in the laboratory, with small slabs simulating the concrete walls.
Those boards were designed in such a way that the results could provide information about characterization, from the point of view of thermal performance of concrete walls with EPS. The EPS used was of two kinds, beads and recycled. In the concrete type A, was replaced the entire volume of coarse aggregate gravel for the EPS.
It was verified the influence of addition of EPS on some properties of concrete using cylindrical specimens of 10 cm diameter by 20 cm high. Samples were tested for the determination of compressive strength, density, void ratio, absorption by immersion and capillarity. Consistency and density of fresh concretes have been evaluated.
The entire process was conducted in the laboratory in accordance with the Brazilian standards and methods. The developed experimental program was divided into the following stages: selection and characterization of the material compost of mixtures, study and choice of the proportions, molding of concrete specimens and the concrete slabs, characterization tests of fresh and hardened concrete and thermal test.
The CPV cement was used as the type of cement most used in buildings of concrete-walls, due to the need to remove the concrete forms quickly. Both the beads and the recycled EPS particles have diameters ranging from 1. The recycled EPS was acquired crushed, however as the particle size were larger than the given to the production of concretes greater than 4.
Table 1 presents the consumption of concrete materials used in this research. CBP: Concrete type B, with EPS pearls incremented, replacing the total volume of coarse aggregate gravel and the volume of 70 liters, representing CBR: Concrete type B, with addition of recycled EPS, replacing the total volume of coarse aggregate gravel and the volume of 70 liters, representing Despite the EPS being of a low-density material, it presented easy handling and good dispersion in the concrete, so the concrete with EPS can be produced from the conventional way in concrete mixer.
All experiments were held to 28 days with cylindrical specimens of 10 cm diameter and 20 cm of height for every concrete type cured by immersion in water until the day of the tests. To evaluate the thermal performance through the heat flow has been adapted the test proposed by Shadnia, et al. Cubic moulds were involved with rockwool insulation. Finally, three temperature sensors thermocouples type K were installed on each cubicle, two self-adhesive sensors at the center of the top and bottom surfaces of the slabs and another inside the cubicle as shown in Figure 3.
These sensors will be simply named top, bottom and inside sensors, respectively, in the discussion later. The five samples were placed in a space without shadows or obstructions on a sunny day. After connecting all sensors to a data acquisition system, temperatures were recorded for 24 hours starting at in the morning. The temperatures were measured every 50 seconds and stored in a data acquisition system.
This procedure had as purpose to analyze the difference in heat between the 3 thermocouple of each sample and evaluate the effect of the increase in EPS mixtures related to the variation of temperatures and heat flow to inside of the boxes. It was possible to observe important features such as homogeneity of the mixture; absence of segregation or EPS floating and absence of bleeding in fresh concrete. In addition to the slump test, it was also evaluated the density of fresh concrete, the results can be seen in Table 2.
According to Catoia [ 9 ] the concrete with EPS, being composed of mortar and EPS beads, presents typically a flow greater than a conventional concrete. In relation to densities, the concretes with EPS were obviously lighter than conventional concrete, but when compared to each other, the concretes with beaded EPS showed slightly higher density to the respective proportions concrete with recycled EPS, this fact can be explained, because as already demonstrated the density of the EPS in beads is greater than the recycled EPS.
As described earlier the test was held to 28 days. In Table 3 are the average results of resistances evaluated. It was noted that the increase of EPS contributed in a negative way to the strength of concrete, the concretes with EPS beads presented a slightly superior strength than the concrete with recycled EPS, this is probably because the EPS in beads has a more rigid structure than the recycled, proven by its greater density.
However, it is known that the maximum request to compression in family residence buildings in concrete walls is less than 1 MPa. The tests for the determination of density, water absorption by immersion and void ratio were held to 28 days.
The results can be seen in Table 4 , where it may be noted that both the presence as enhancing EPS increased absorption and voids content and reduced density in relation to the reference concrete. This was due to the trend of incorporating more air for the mixture to add EPS in concretes. This increased the absorption and the porosity. That observation was repeated in all the concretes with EPS in beads or recycled. The addition of the EPS in beads resulted in greater absorption and voids ratio than the concretes with recycled EPS, the CBP concrete presented the greatest absorption of This fact can be explained due to the concrete type B having a higher amount of EPS in its constitution.
The concretes with beads presented more voids content, probably due to the spherical shape and its uniform particle size composition which may have disadvantaged the particles grouping.
The test for evaluation of absorption for capillarity was held at 28 days, the values of water absorption for capillarity C obtained after 3, 6, 24, 48 and 72 hours of partial immersion can be found in Figure 4. Contrary to what was observed in the test of absorption by immersion, the concrete with greater water absorption by capillarity was the reference concrete and concrete with lower water absorption by capillarity was the concrete type B with beads CBP.
It is observed according to the results a trend of EPS, especially in higher levels, cause a decrease of capillary absorption. Evaluating the absorption 72 hours after partial immersion in water the addition, EPS in beads demonstrated greater efficacy in reducing absorption for capillarity, the CBP concrete presented a After the last weighing the specimens were broken down for the measurement of the height of rising capillarity.
Follow the rising capillarity values largest to smallest value: CR 9. According to Helene [ 10 ] the capillary absorption is the most common and intense aggressive agents penetration into concrete. Still according to the same author absorption by capillarity is one of the most difficult factors to be controlled because concrete is a hydrophilic material has great affinity with water. The smaller the diameter of the capillary pores, greater capillary pressures developed and consequently the greater the depth of concrete met by water absorbed.
However the greater the diameter of these capillary pores the less is the depth, but greater the amount of water absorbed. Although more important than the size of these capillaries is the interconnectivity between them.
In order to minimize the effect of absorption, Mostardeiro [ 11 ] and Barin [ 12 ] suggest that the capillary absorption can be controlled with use air-entraining agent, which allow the disrupt communication between the pores by the incorporation of tiny air bubbles in its interior, reducing the capillarity in the system. Therefore, as the EPS is waterproof and acts as an air-entraining agent in concrete, that allow these air bubbles inside of mixtures disrupt communication between the capillary pores.
To facilitate the understanding and analysis of the results the sensor on top of slabs was named 1 , the sensor on bottom of slabs named 2 and the sensor inside the compartment 3.
For example, the sensor inside the compartment of reference concrete was named CR Figures 5 , 6 and 7 show, respectively, the temperatures on top of slabs, on bottom of slabs and inside the compartment, measured during 24 hours for the five samples. Figure 6 indicates that the temperature on bottom of slabs containing any type of EPS start rising a few minutes later than the reference concrete slab.
During the period of increased temperature of am to pm the temperatures on bottom of the EPS slabs were on average of 1. Obviously, because they have a higher EPS content, the time it takes to raise the temperature takes longer for type B concretes than type A concretes. It can also be seen that after the temperature peaks, the time it takes for the temperature starts to fall is slightly slower with EPS increase.
Thus, the EPS well perform the function of attenuating the variation in the internal temperature, due to the change in temperature outside of the compartment. The measured temperatures inside the compartments show trends similar to those on bottom of slabs, as can be seen in Figure 7. During the period of increased temperature from am to pm, the air temperature inside the compartments containing EPS ranged around 1.
The largest temperature difference happened to pm between the sensor inside the compartment of the reference concrete CR-3 and the sensor inside the compartment of type B concrete with recycled EPS CBR-3 at a value of 6. Table 6 shows a correlation between the highest temperature and time when it occurred to each of the sensors. Analyzing the results of Table 6 is very clear that the incorporation of EPS influenced on temperature decrease and the time delay of the temperature rising, especially in type B concrete with recycled EPS CBR.
The absorption by immersion and void ratio increased in all mixtures with the addition of EPS. However, the absorption for capillarity reduced with the replacement of mineral aggregates by EPS, reaching a reduction of The thermal tests showed that all concretes with EPS proved to be more effective in reduce the temperature than the reference concrete.
From this research, proposed dosage studies with other levels and dimensions of particles of EPS to improve the mechanical properties and microstructure analyses of EPS concrete, evaluating, among others, the distribution and pore dimensions in order to better understand the behavior of these materials. Concreto estrutural leve. Belo Horizonte - Minas Gerais. Experimental study of geopolymer mortar with incorporated PCM.
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This work studied the properties of lightweight concretes with addition of expanded polystyrene EPS for structural walls applications. EPS for being a material produced on a large scale and has low density, produces a large volume of waste. These residues are not reused, especially in Brazil. Given that, in order to perform a comparison of the performance of concrete with adding of EPS in pearls and recycled, it have been manufactured five concrete types, a control without addition of EPS and four other samples with two different percentages of EPS. The mechanical compressive strength and physical density, voids content, absorption by immersion and capillarity properties were evaluated, and tests were carried out to evaluate the thermal performance of the mixtures studied.