One of the main environmental problems experienced in this generation is plastic pollution and its improper waste disposal. Single-use plastic (SUP) sachets, usually made out of PET, contribute massively to this crisis, in the Philippines at least, amounting to roughly fifty percent of the country’s mismanaged plastic waste, approximately 59.8 billion per year is used [1]. Plastic takes about 20 to 500 years to decompose and due to its continuous growth in production, plastic isn’t going anywhere and will remain in landfills and oceans for a long time. To promote sustainable construction practices, it is imperative to conduct extensive research on PET concrete bricks as it holds great potential for reducing plastic waste.

This research aims to design and develop a brick-style concrete with recycled PET focused on improving its compressive strength and water absorption. To attain this, the researchers will first determine all the materials and data needed to make the brick-style concrete with recycled PET from SUP sachet. Along with the collected and cleaned SUP sachets, the researchers will be preparing the materials required in fabricating prototypes using 0%, 1%, 3%, 5%, 7% and 9% PET-to-fine aggregates ratio and test its compressive strength and identify its water absorption rate. Based from the tests conducted, the researchers will identify the PET ratio that has the highest compressive strength and lowest water absorption. After that, the researchers will be utilizing the optimum ratio along with the designed geometric dimension, behaton shape, in constructing a pathway in Central Colleges of the Philippines (CCP). Lastly, the researchers will make a cost benefit analysis to compare the brick-style concrete to conventional concrete bricks.

1. LITERATURE REVIEW

2.1.  Concrete bricks.

The usage of bricks and concrete in construction, engineering projects, and landscape design was widespread. The composition of the raw materials, compressive strength, initial water absorption, firing shrinkage, and a host of other factors all affect the quality of brick. [2]. Brick samples containing 5% PET outperform all other samples, including the control sample, in both the compressive and flexural strength tests. Compared to the control, it exhibited a decreased density and water absorption. [3]. 60 mm thickness shall be implemented for concrete bricks used for pedestrian pathway [4].

2.2.  Compressive strength.

Concrete's compressive and flexural strengths are two crucial factors that should be considered, especially during the designing phase of structures and infrastructure [5]. According to the ASTM C902, the minimum mean compressive strength of a paving brick is 20.7 MPa [6]. Additionally, based from DPWH Standards, interlocking concrete bricks should at least have a minimum compressive strength of 24 MPa [4].

2.3.  PET (Polyethylene Terephthalate).

PET, a type of thermoplastic, is known as one of the most produced plastic materials globally. It is generally used as a packaging of food, beverage, and daily necessities for the reason that it is shatterproof, recyclable and non-reactive to food or water, but it is recommended to only use it once [7]. Considering that the construction industry is responsible for the largest consumption of natural resources, studies imply that the industry has the highest potential to utilize PET wastes as a raw material in manufacturing various products such as eco-bricks [8]. In the summary of previous works incorporating PET in interlocking concrete blocks shows improved compressive strength and reduced water absorption due to the lessened pore spaces caused by the PET fibers binding the concrete [9].

2.4.  Water absorption.

Concrete durability is predicted using water absorption because water makes it easier for hostile agents to penetrate the material. Water in concrete can also result in cracking because of thermal expansion and contraction brought on by temperature changes [10]. The absorption test is carried out to determine the porosity of the bricks in relation to water absorption. It is preferred that the weight of a brick soaked in water should not be 20% greater than the weight of the dry brick [11].

2.5.  Waste reduction.

The remarkable qualities of PET, such as thermal resistance, lightweight, high transparency, superb impact, and comparatively low cost, are linked to its rising application. Therefore, switching to new PET mix and composites is an effective way to recycle PET and minimize plastic waste. This should be collected due to the increased volume of PET solid waste, which is harmful to human life and exacerbates environmental difficulties [12]. With the intent to resolve this issue, the United Nations includes ensuring sustainable consumption and production patterns as Goal 12 in their 17 Sustainable Development Goals.

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