This research seeks to contribute to achieving SDGs 9 and 11 focusing on waste management and recycling HDPE plastic waste as formwork material in construction. Flexural tests were conducted on I-beam specimens with a 2-meter span, employing the Digital Image Correlation (DIC) to capture load and displacement data. Additionally, numerical modelling was performed using ABAQUS to verify the alignment of HDPE beam structural responses with the experimental results. The study presents the load-displacement relationships and displacement contours to evaluate the flexural capacity of HDPE beams. The findings confirm the potential of HDPE beams as an environmentally friendly and sustainable formwork material in construction projects. © 2025 Institute of Physics Publishing. All rights reserved.