Sources Analysis on Rubberized Concrete - Assignment Example

Name Instructor Course Date Rubberized Concretes Literature Review Concrete is a common structural material used in the construction industries. Concretes are used in the construction of roads, pavements, sidewalks and basketball playgrounds among other structures. The use of concrete as a structural material has become common in the modern society. Despite the growing use of concrete as a structural material, concrete has a limitation in the sense that it has low tensile strength (Kumaran et al. 41). Because of these, concrete develop cracks easily and this increases the permeability of concrete. When permeability increases, this allows water and other chemical substances to enter into the concrete, thereby damaging the concrete. To prevent such limitations in concretes, efforts have been made with the technological advancements to discover a way of enhancing the tensile strength of concrete. Accordingly, in the recent years, rubber constituents are being added to the concrete to reduce brittleness (Siddique 152). Currently, most concrete manufacturing companies are using the technology of adding rubber constituents to make strong rubberized concrete because of the technology has proven feasibility due to large piles of tires that ends up in the landfills. In Australia, millions of tires reach their useful life every year. Unfortunately, the majority of these used tyres end up in the landfills, stockpiles, exported or illegally dumped with just a very small quantity being recycled. According to the Australia Department of Environment, approximately 48 million passenger unit (EPU) tyres were disposed off as waste in 2009/2010 (Australian Government Department of Environment par. 2). Of these huge piles of tyres, 66% were thrown into the landfills, illegally dumped or stockpiles. Only 16% of these tyres were recycled while about 18% were exported (Australian Government Department of Environment par. 2). A similar trend is seen in other countries where large amount of tyres are ending up as waste every year. Like in Australia, in the UK, approximately 40 million used tyres end up as waste every year. In the United States, about 285 million tyres are disposed off in the landfills, illegally dumped or added to the stockpiles every year (Naik 4). According to the EPA approximation, the amount of waste tyre problem is two to three billion tyres. In Kansas, for example, it is estimated that one tyre is disposed off per person every year. This implies that, in Kansas along, about 2.4 million tyres are disposed off as waste every year with the current estimates indicating that Kansas has approximately 4.3 to 5.5 million tyres that have accumulated as scrap (Naik 7). Such kind of statistic is reflected in almost all the countries across the globe considering that a large number of the world population currently own a car with some owning more than two. The huge amount of tyres that end up as waste has become a global health and environmental concern worldwide. Burning is the common method used worldwide for disposing-off waste tyres. However, the burning of the huge piles of waste tyres releases huge smoke that ends up in the atmosphere (fig. 1). The smoke is highly toxic and can cause serious health hazard to the local community. Siddique notes that tyres have ash consisting of carbon, titanium, zinc oxide, polynuclear aromatic and silicon dioxide (132). As such, when the tyres are burnt, these toxic chemicals are inhaled by the locals in the surrounding areas, which can cause respiratory problems among other health problems. In Australia, there has been an increased case of respiratory and other health problems that are linked to the smoke emitted from the burning of waste tyres (Australian Government Department of Environment par. 4). Smoke from the burning tyres is also an environmental problem because it generate large amount of carbon that is responsible for the global warming problem. Currently, global warming is a global problem. Scientists estimate that the planet’s average temperatures have increased significantly since the turn of the century. These have resulted in climate change that includes increased drought, flooding, glacial melting, and rising sea levels among others. Fig. 1 Source: Khalil et al. (45). Other than burning, large quantity of used rubber usually ends up in landfills where they cause environmental problems (fig. 2). Rubber in the landfill causes environmental pollution because rubber is non-biodegradable (Siddique 133). As such, when they are disposed off in the landfills, they form huge piles that cause an environmental nuisance. Fig. 2 Source: Khalil et al. (45). The fact that tyres are non-biodegradable makes the stockpiles of tyres is a nuisance to the public since they become a breeding ground for mosquitoes. In Pakistan, for example, the stockpiles and landfills of tyres have become a breading place for Dengue mosquitoes. Public health report in the country indicates that malaria caused by mosquitoes has become a public health issue in Pakistan. According to the report, more than 26,270 cases of the disease and more than 156 deaths reported since 2010 (Gauff par. 4). In the last 2 months of 2012, more than 6,666 cases of the disease caused by Dengue mosquitoes were reported. However, the health and environmental hazards caused by waste tyres is about to end with the increased use of waste tyres in the manufacture of concrete. With the advances in concrete technology, it has become possible to make more durable and strong concrete by incorporating rubber particles in the concrete mixture. Siddique noted that rubberized concrete has good esthetics, small unit weight than traditional concrete and have acceptable workability (134). Unlike the traditional concrete, rubberized concretes have the ability to absorb large amount of plastic energy under tensile load and compression. Properties of Rubberized Concretes In recent years, several researchers have devoted their time and resources in the study of the properties of rubberized concretes that make them unique and preferable for use as structural materials. One such study was conducted by Karahan et al. found that the addition of crumb rubber in a concrete as fine particles reduced the filling and passing-capacity (413). However, the researchers did not observe any significant reduction in the freezing-and-thawing and resistance to corrosion of concrete when 10% of rubber crumb was added to concrete. However, when the quantity of crumb rubber was added beyond this level, the durability performance of concrete was affected significantly. In this respect, an increase in the amount of rubber particles to the concrete resulted in a significant increase in the durability performance of the concrete. A study by Tang, Cui and Lo found that the addition of rubber chips in concrete resulted in an increase in the coefficient of water permeability of concrete (1251). In a follow-up to Tang and colleagues’ study, Anwar et al. conducted another study that found that rubberized concretes have the potential of providing good energy dissipation ability and ductility (5). Accordingly, Anwar and colleagues concluded that rubberized concretes are effective for use in seismic applications because of their ductility and ability to dissipate energy (5). This implies that rubberized concretes are good for use in buildings because they have the capacity to withstand huge tensile stress, such as those caused by earthquakes. A study conducted by Benazzouk, Douzane and Queneudec, however, focused on testing the sorptivity and hydraulic diffusivity features of rubberized concretes (24). The researchers observed from the study that addition of rubber chips in concrete reduces the sorptivity and hydraulic diffusivity of concrete by minimizing the rate of water absorption. In addition, Benazzouk and colleagues noted that addition of rubber to concrete reduced the permeability of concrete (25). The reduction in permeability was linked to the presence of rubber particles in the concrete. Besides, the researchers observed that the presence of rubber particles in concrete improved the performance of concrete when in contact with fluid. Benazzouk and Queneudec experiment supported the study by Siddique study that found that mixture of concrete with rubber particles significantly increased the durability of concretes (135). Further study by Allen found that the addition of rubber chips to concrete caused a significant reduction in the brittleness Index of concretes (par. 6). Based on their observations, the researchers concluded that rubberized concrete are suitable for structural work as they can withstand strong stress or tension subjected on the concrete. Advantages of Rubberized Concretes Affordable in terms of Cost Affordability in terms of cost is one of the main advantages of rubberized concretes. Kumaran et al. study show that its costs up to 50% less to produce a rubberized concrete compare to a conventional asphalt overlays (43). This is a great advantage because it results in significant cost saving. The low cost of making rubberized concretes is attributed to the fact that it cost less to acquire waste tyres that sometimes just end up in the landfills. As such, experts recommend the use of rubberized concretes as it will help those involved in construction save significant cost. Besides low cost of acquisition of rubber use in the production of rubberized concretes, the technology used in turning rubber into chips is also simple and do not require the use of a lot of labor (Siddique 134). Under the technology, the crumb rubber is made through mechanical shredding, which is very simple and less labor intensive. In the same light, rubberized concretes are cheap in terms of cost due to low maintenance involved. Unlike normal concretes that develop cracks after a short period, rubberized concretes are highly durable and this means that they do not require frequent maintenance and these results in significant cost saving (Kumaran et al. 44). Additionally, the use of rubberized concretes results in the elimination of large quantities of tyres that could otherwise end in the landfills and recycled. In this respect, there use in the production of concretes help in eliminating the cost that would otherwise be used in recycling the tyres. Durable Durability is one of the reasons for the increased popularity and use of rubberized concretes. When using a concrete as a structural material, one of the features being looked at is the ability of the concrete to last long. Any structure should not be built using a concrete that would not last or require constant maintenance and replacement. Fortunate, rubberized concreted have been found to possess the feature of durability. Most studies have found that concretes that are made by adding crumb rubber are very strong and last long. Besides, they are capable of withstanding a lot of stress. Accordingly, this quality makes them a suitable structural material for the construction industry. The increased durability of rubberized concrete was proven by Benazzouk, Douzane and Queneudec study that tested the freeze-thaw durability of rubberized cement composites which involved the use of two different rubber aggregates namely Compact Rubber Aggregate (CRA) and Expended Rubber Aggregate (ERA) (26). The volume ration of the mixture was in the range of 9 to 40%. From the experiment, Benazzouk and Queneudec observed that the durability of the cement-rubber composite increased significantly for the composite containing 30 to 40% rubber by volume. However, the composite with ERA aggregates experienced improved durability than composite with CRA aggregates. This finding was supported by a follow-up study conducted by Khalil, Abd-Elmohsen, and Anwar that also tested the freeze-thaw durability of rubberized concretes (45). The researchers used crumb rubber measuring 0.5-1.5 mm, 2-8 mm and 5-25 mm. The researchers found that crumb rubber has a potential for use as a freeze-thaw resisting material in concrete. This is after the researchers observed the cement-rubber composite showed good performance under freeze-thaw conditions than normal concretes. Low coefficient of Thermal Expansion Rubberized concretes are suitable for use in construction of floor and pavements because of their low coefficient of thermal expansion. This property is important because it ensures that the pavements made of rubberized concretes do not crack (Kumaran et al. 44). There are many instances where pavements and floor made using plain concretes have been seen develop cracks that makes the surfaces weak and pose danger to the people as shown in figure 3. Figure 3 is an example of a surface made of plain concrete. This is where rubberized concretes are useful. Unlike plain concretes that crack when subjected to a lot of heat, rubberized concretes never develop cracks because of their low coefficient of thermal expansion. As rubberized concrete matures, it shrinks instead of expanding. This ensures that it remains compact and avoids developing cracks as is the case with plain concretes. Fig. 3 Plain concrete Rubberized concrete Source: Siddique (141). Noise-free Noise is an environmental hazard that needs to be reduced to the lowest level possible. Fortunately, the use of rubberized concretes in the construction of roads and pavements has been shown to reduce the amount of noise produced on such surfaces significantly. Some studies have found that the use of rubberized concretes reduces the noise level products by such surfaces from 4 to 10dB (Khalil, Abd-Elmohsen, and Anwar 49). These makes is new technology very useful for construction of city roads and pavements. Eliminate Waste Waste from used tyres is an environmental hazard in almost all countries across the globe. As indicated earlier, approximately 48 million passenger unit (EPU) tyres were disposed off as waste in 2009/2010 with this trend experienced every year. Of these huge piles of tyres, 66% were thrown into the landfills, illegally dumped or stockpiles. Only 16% of these tyres were recycled while about 18% were exported. When these tyres are thrown in the landfills or burnt, they cause environment pollution that is a health hazard (Khalil, Abd-Elmohsen, and Anwar 47). Putting them in stockpiles also creates a breeding place for mosquitoes, which spread malaria and other diseases as has been the case in Pakistan. Therefore, the rubberized concrete technology is beneficial to the environment since it ensures that all the used tyres do not end in the landfills or burnt to pollute the environment, but is instead used to produce concretes that are of economic value to the economy. Does not Crack Rubberized concretes are suitable for use as structural materials because of their high water resistance. Studies have shown that rubberized concretes have low liquid absorption rate (Gauff par. 5). As such, this makes it a suitable structural material for the construction of pavements and roads among other surfaces as this also ensures that it does not develop cracks. The fact that rubberized concretes do not develop cracks is also advantageous because it ensures maximum safety of the users of the surfaces made on these structural materials. Safety is a pertinent issue that must be considered when using a structural material. Fortunately, unlike plan concretes that develops cracks easily and poses risk to users, the high water resistance nature coupled with the low thermal conductivity of rubberized concretes makes them safer to use in various areas of applications. Disadvantages of Rubberized Concretes Although rubberized concretes have many advantages that make them suitable structural materials, this technology also has a share of shortcomings that are worth highlighting. The first main disadvantage of rubberized concretes is that they have weak compressive and tensile strength. Studies have consistent found that any addition of rubber crumbs into concrete mixture reduces the tensile and compressive strength of the resultant mixture. This is shortcoming of this new technology because a good structural material should have good tensile and compression strength in order to withstand a lot of stress exerted on the surface. This property of rubberized concrete was discovered by Khalil, Abd-Elmohsen, and Anwar that found that addition of 19mm of rubber chips and crumbs to the concretes reduced the tensile strength of the concrete by about 50% and compressive strength by 85% (48). The other disadvantage of rubberized concrete is that the process of producing the rubberized material is slow and time consuming. Unlike the plain concretes that are simpler and faster to make, rubberized concretes is a step-by-step process as it starts with the preparation of rubber particles, which is a time consuming considering that the process is slow. Once the rubber chips have been prepared, they have to be molten and mixed with the concrete, a procedure that is not just costly, but is time consuming (Purdue University par. 6). Because the processes involved in the production of rubberized concretes are many, this normally results in a delay in the implementation of a project. For instance, when the technology is used in the construction of roads, the construction of such roads might take longer than if plain concretes are used because of the many and time consuming processes involved in the production of the mixture. Additionally, investing in rubberized concrete technology is a risky move at the moment as the viability of the technology is still questionable. Although many researchers feel that rubberized concretes are here to stay, the fact that his concrete making technology is still at its infancy stage and cannot be fully relied on until such a time that its economic viability and sustainability is proven (Purdue University par. 8). Applications of Rubberized Concretes Rubberized concretes have are applied in many areas where it is used as a structural material. The first area that rubberized concretes are widely in use is in the construction of roads. The material is used for road paving. It has been noted that roads that are made using these new concrete is not only environmental friendly because of less noise produced on such surface, but also because such roads are very durable (Gauff par. 2). Because rubberized concretes do not develop crack easily as they have low coefficient of thermal expansion, such roads usually last longer than roads paved using normal concretes. Secondly, rubberized concretes are widely used today in precast sidewalk panel construction, precast roof of buildings and in non-load bearing walls. Additionally, the rubberized concretes are increasingly being used in the construction of pavements, road intersections, skid restaurant ramps and recreational court construction (Purdue University par. 3&4). Besides it has been shown that the technology is being applied in the various architectural applications that include nailing concretes in areas where high strength is not needed. Moreover, rubberized concretes are increasingly being used in wall panels, in putting up Jersey barriers that are subject to contact, as well as in rail road, where they can be used in fixing rails to the ground. Further, rubberized concretes are reportedly being in use in the construction of basketball play grounds. Because of the durability of the rubberized concretes, it is widely being adopted in the construction of most of the modern basketball courts (Gauff par. 2). Conclusion The literature has shown that large amount of tyres are currently disposed off as scrap. In Australia, the UK and the US, it has become clear that approximately 46 million, 40 million and 285 million tyres are added to landfills, stockpiles or illegally dumped while just a few percentage is either recycled or exported. However, these large piles of tyres that are disposed off in the landfills not only pose a health hazard to the people, but pollute the environment. For instance, when the tyres are burned, they produce gases that not only cause respiratory health problems, but also increase the amount of greenhouse gases into the atmosphere, which subsequently increases the global warming effect. The huge stockpiles of the tyres also provide a suitable breeding ground for mosquitoes, which spread diseases as has been in Pakistan. Fortunately enough, the advances in technology has resulted in the discovery of a new way of making concretes through rubber addition. It has been shown that, when rubber chips and crumbs are added to concrete, this results in increased durability of the concretes and their ability to withstand a lot of stress. As such, many used tyres are currently being sought by firms that manufacture concretes using this technology. The advantages of rubber concretes include being cost effective, durable, and safe and less noisy and environmental friendly. Despite the advantages, rubberized concretes have some shortcomings that make them less suitable for use as a structural material. They include the fact that rubberized concretes have low tensile and compressive strength with any addition of rubber, preparing rubber particles is also a slow and times consuming, as well as the fact that the viability of the technology remains in question. However, as indicated in the literature, rubberized concretes are currently being used in road paving, construction of pavements, basketball pitch, railroad fixing, wall panels and nailing concretes. Works Cited Allen, Floyd. “Crumb Rubber Concrete.” Precast Magazines, May 30, 2010. http://precast.org/2010/05/crumb-rubber-concrete/ Anwar, Usman, Hassaan Masood, Osama Bashir, and Yasir Mehmood. Permeability and Strength Properties of Rubberized Concrete. University Of Engineering and Technology, Lahore, Pakistan (2014): 1-14. Print. Australian Government Department of Environment. Product Stewardship for End-Of-Life Tyres - Fact Sheet. Web. 13 May 2016 http://www.environment.gov.au/protection/national-waste-policy/publications/factsheet-product-stewardship-end-life-tyres Benazzouk A, Douzane O, Queneudec M. Transport of fluids in cement–rubber composites. Cem Concr Compos 26(2004):21–9. Print. Gauff, Nate. Rubberized Asphalt Concrete (RAC). Web. 13 May 2016 http://www.calrecycle.ca.gov/tires/rac/Benefits.htm Hossain, M., M. Sadeq, L. Funk and R. Maag. A Study of Chunk Rubber from Recycled Tires as A Road Construction Material. Proceedings of the 10th Annual Conference on Hazardous Waste Research (2010); 188-197. Print. Karahan, Okan, Erdogan Ozbay, Khandaker M. A. Hossain, Mohamed Lachemi, and Cengiz D. Atis. Fresh, Mechanical, Transport, and Durability Properties of Self-Consolidating Rubberized Concrete pages Materials 109. 4 (2012)” 413-420. Print. Khalil, Eehab, Mostafa Abd-Elmohsen, and Ahmed M. Anwar. Impact Resistance of Rubberized Self-Compacting Concrete. Water Science, 29. 1 (2015): 45–53. Print. Kumaran, Senthil G., Nurdin Mushule and M. Lakshmipathy. A Review on Construction Technologies that Enables Environmental Protection: Rubberized Concrete. American J. of Engineering and Applied Sciences 1. 1 (2008): 41-45. Print. Naik, Tarun R and Rafat Siddique. Properties of Concrete Containing Scrap Tire Rubber–An Overview. Center for By-Products Utilization. The University Of Wisconsin–Milwaukee (2002): 1-20. Purdue University. Use of Recycled Tire Rubber in Concrete. Web. 13 May 2016 http://rebar.ecn.purdue.edu/ect/links/technologies/civil/rubberizedcon.aspx Siddique, Rafat. Waste Materials and By-Products in Concrete. London: Springer Science & Business Media, 2007. Print. Tang, Wai C., Hong Zhi Cui and Yiu Lo. Properties of Concrete Containing Scrap-Tire Chips (2011): 1251-1256. Print. Read More