Effects of plastic wastes as partial aggregate substitute to concrete hollow blocks

• Main Authors: Cuartero, Maejann E., Villanueva, Nikko Paolo P.
• Format: text
• Language: English
• Published: Animo Repository 2016
• Subjects: Aggregates (Building materials) > Testing; Hollow bricks > Testing; Plastics > Recycling > Philippines
• Online Access: https://animorepository.dlsu.edu.ph/etd_bachelors/6215
• Institution: De La Salle University

There is a need to address the issue of recycling plastic waste and providing means of livelihood at Southville 7, Don Bosco, Calauan, a relocation site of typhoon victims in Metro Manila. Hence, this community engagement involves a research on how to produce quality concrete hollow blocks (CHB) mixed with waste plastic. The main significance of this study is that it provides livelihood and helps reduce the plastic wastes in relocation site thus promoting a sustainable and environment friendly community. The study aims to assess the effects of using plastic bags (PB), noodle wrappers (NW), and a combination of both (COM) as substitute to fine aggregates in non-load bearing concrete hollow blocks (CHB). The plastic wastes, plastic bags and noodle wrappers, were shredded and a base mix design of 1:12 (cement: sand) ratio was used in the mix. Different percent substitutions, specifically 2.5%, 5%, 7.5% and 10%, were considered for each mix. The substitution was done by volume through the use of a volumetric box. The specimens were subjected to a compression test on the 7th, 14th, 21st and 28th day of immersed curing. Comparison on the strength properties of the conventional and the CHB with plastics were done. Results show that as the percent substitution increases, the compressive strength of the CHB decreases. As to the weight classification, the conventional CHB and the maximum substitution of 10% in the CHBs still fall under a normal weight concrete. A separate batch of 2.5% PB-CHB was also cured by sprinkling, and was tested on the 28th day to verify its effects. It was found out that immersion proved to be better than sprinkling as a mode of curing. Moreover, cylindrical samples were subjected to stress-strain test on the 28th day for all batches of NW-CHB, 5% of the PB-CHB and COM-CHB, and conventional CHB. This set-up was considered to observe the changes in behavior due to the increase in percent substitution and the use of different types of plastics. Results show that PB-CHB outperformed the other CHB with plastics due to the plastic bag's better stretchable property, compared to the noodle wrappers. In addition, plastics, in general, provide additional deductility to the concrete enabling them to tolerate more deformation at lower loads. Lastly, it was observed that noodle wrappers, at higher substitutions, have the most detrimental effect to the mechanical property of concrete. An optimum mix design was chosen based on economy and strength. It was found out that the 10% substitution yields the most savings, whereas the 2.5% offers the highest strength.