concrete and recycled plastic

Globally, there has been a rise in the use of plastics due to the advantages of human life. However, the rise in these plastics has had devastating consequences on the atmosphere in particular. Due to the lack of plastics due to their non-degradable origin, experts have been exploring for decades how plastic recycling can be used properly. One of the findings of these studies was the discovery that recycled plastics can be used in concrete. The aggregate plastic used in construction is solid and less costly to produce relative to standard concrete. This research has detailed how plastics are used to develop concrete and the varying benefits that are achieved.
Recycled Plastic in concrete
Introduction
For decades, plastics have become an integral part of the human life. The number of plastic that human beings have been using annually has continued to increase. Its strength, low density, fabrication capabilities, user-friendly designs, light weight, long life, and low costs have been the factors which behind the significant growth (Ghernouti, Rabehi, Safi, & Chaid, 2011). Plastics have been used for many uses including industrial and automation application, packaging, medical delivery systems, water desalination, artificial implants, food preservation, flood prevention, housing, security systems, and communication materials among other uses. With such as varying and large applications, plastics have become critical contributors of the growing solid waste stream. In the United States, in 1996 plastics were approximated to contribute to 12 percent of the municipal solid waste (MSW) (Ghernouti, et al. 2011).
Often waste plastics that are collected from solid waste streams are an assorted of plastics which are contaminated. Due to this, it is very challenging to identify, segregate, and purify various forms of plastic. In the stream of plastics, the major component are the polyethylene forms followed by Polyethylene terephthalate, and other small amounts such as High density polyethylene, Low density polyethylene, Polystyrene, and Polypropylene (Rao, Jha, & Misra, 2007). While the growth of plastic use has been because of the benefits human beings get, they also have shortcomings. First, the production of plastics involves incorporation of chemicals which are harmful and the lack of an environmental assessment on their effect, the health of human beings is exposed to risk (Siddique, Khatib, & Kaur, 2008). Moreover, the disposal of these plastics to the environment negatively affects it. This is because plastics are non-degradable and before they break-down they take a long time sometimes estimated to be thousands of years. Nevertheless, innovation has made it easier to recycle the used plastics and reduce the global growing concern.
Recycling plastics has many benefits to the society including reducing the amount of solid waste in the landfill, reduction of energy consumption, as well as the conservation of non-renewable fossil fuels. For many years, research on how by-products can be used to augment concrete properties has conducted. Recent decades have seen research done on how by-products such as silica fume, fly ash, glass cullet can be used in civil constructions (Siddique, Khatib, & Kaur, 2008). The use of these materials in concrete has been because of the environmental constraints in safely disposing waste. Attention has been focused on how industries can safeguard natural resources in addition to recycling waste. One of the developments that various researchers have discovered is the use of recycled plastic in the concrete industry.
To solve the problem of disposing large amounts of plastics into the environment, re-using plastics in the concrete industry has been regarded to be appropriate and the most feasible application. Plastics that have been recycled can be used as coarse in concrete aggregate. In other words, plastic which has been recycled can be used in replacing some of the aggregates which are found on the concrete mixture. When this is done, it contributes positively towards the reduction of total weight unit of the concrete. Apart from this, using a mixture of plastics in the concrete lowers the density and adds tensile and compressive strength of the concrete. The splitting tensile strength of concrete that has been made with post-consumer plastic aggregates often decreases with an increase in the amount of plastic aggregates (Siddique, Khatib, & Kaur, 2008). According to Siddique et al. (2008), the splitting tensile strength decrease by 17 percent for concrete which had 10 percent plastic aggregates (Siddique, et al. 2008). The effect of cement-water ratio of strength is less prominent in plastic concrete. The reason behind this is because of the fact that plastic aggregates have the capability of reducing the bond strength which is present in the concrete. Thus, concrete failure occurs when the bond between the plastic aggregate and cement paste fails. Additionally, the introduction of plastic in concrete often makes concrete ductile which increases the capability of concrete to deform before it fails. Siddique, et al. (2008) report that concrete that has plastic aggregates exhibits a more ductile behavior than concrete with conventional aggregates. This feature makes concrete to be useful in circumstances where it is being subject to weather conditions which are harsh such as thaw, freeze, contraction, or expansion. Moreover, the ductile behavior might have a significant advantage in the reduction of propagation and formation of cracks.
Research has shown that including recycled plastic aggregates in the concrete used in the construction of buildings has shown to be beneficial in an energy viewpoint (Rao, Jha, & Misra, 2007). Using plastic aggregates helps to keep the interior cooler when the temperature from outside raises when compared to the conventional concrete. Plastic aggregates that have been recycled can be efficiently and effectively used in the overlay and repair of cement concrete surfaces that have been damaged in dams, floors, bridges, and pavements. Additionally, recycled plastic can be used in various recast applications like utility components for instance junction boxes, underground vaults, sewer pipes, drains for acid wastes, and power line transmission poles. References
Ghernouti, Y., Rabehi, B., Safi, B., & Chaid, R. (2011). Use of recycled plastic bag waste in the concrete. The International Journal of scientific publications: Material, Methods and technologies.
Rao, A., Jha, K. N., & Misra, S. (2007). Use of aggregates from recycled construction and demolition waste in concrete. Resources, conservation and Recycling, 50(1), 71-81.
Siddique, R., Khatib, J., & Kaur, I. (2008). Use of recycled plastic in concrete: a review. Waste management, 28(10), 1835-1852.