Page 53 - New Trends in Green Construction

A STATE-OF-THE-ART REVIEW ON CONCRETE WITH PLASTIC AND
RECYCLED PLASTIC MACRO FIBERS
Pietro A. Vaccaro, Adela P. Galvin, Antonio López-Uceda, Jesús Ayuso
Keywords: sustainable construction, macro plastic fibers, circular economy, plastic waste recycling, mechanical properties, durability.
1. Introduction
One of the current priority objectives of the EU is to move from a take-make-waste extractive industrial model to a circular economy. In the EU, above 25 millions of tons of plastic wastes are generated per year and just 30% by weight is recycled, far from the 50% in 2025 and 55% in 2030 stablished by European (European Parliament, 2018). This fact clearly indicates how important is to look for innovative technologies such as to consider this stream waste as a raw- second material. Construction sector is in continuous evolution, and fibers- reinforced concrete is an example of innovative solutions. The plastic fibers are useful in providing greater resistance to plastic shrinkage cracking and service-related cracking, and numerous research studies on fibers reinforced concrete have been developed (Li, 1998). The studies demonstrated that concrete made from macro plastic fibers is a composite material that could replace a part of the steel reinforcement in upstream concrete. Therefore, the exploration of the possibilities of reusing different types of plastic wastes in concrete manufacturing would lead to unbeatable results while plastics are daily consumed worldwide and the production this waste has increased immensely during the past 50 years (Gu, 2016).
2. Materials and methods
The present short communication summarizes the current published literature discussing the physicaland mechanicalpropertiesofconcretewithplasticmacrofibers.Thus,theperformanceof the concrete with macro plastic fibers (PF), including the recycled ones are mainly influenced by the following variables: type of plastic, dosage of plastic fibers introduced into the mixture, dimensions and shape of fibers and water to cement ratio. In addition, the assessment of environmental exposure and the most important physical and mechanical properties of concrete containing PF: workability, air content, density, elastic modulus, compressive strength, flexural tensile strength durability have been evaluated.
1.1. Physical properties of concrete containing plastic fibers
Workability: according to various researchers, the workability, with the same water to cement ratio, depends on the amount of recycled PF used. To determine the workability of the fresh concrete was used the slump test. The results obtained were that the slump decreases with the increase in the percentage in volume of PF (Pelisser, 2012).
Air content: most of the studies (Richardson, 2006) indicated that the PF do not significantly affecttheair contentofreinforcedconcretewithPF.
Density: the density of the concrete with PF have a not significative reduction respect to the conventional concrete due to the small volume of the PF added in concrete (Karahan, 2011).
1.2. Mechanical properties of concrete containing plastic fibers
Elastic modulus: the modulus of elasticity of a concrete made with PF it is not very different
from that of ordinary concrete, due to the low percentage by volume of PF (Pelisser, 2012).
Compression strength: many studies have shown that the compressive strength of concrete containing PF improved upon addition of plastic fibers (Kakooei, 2012). On the contrary, other experiments reported reductions in the compressive strength of concrete containing PF (Fraternali, 2014).
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New Trends in Green Construction