Enhancing concrete performance using protective coating fabricated by recycled waste material

The motivation behind this research is to enhance concrete using a coating fabricated from waste materials. Polyethylene terephthalate (PET) was added to asphalt (AP) cement of 60/70 penetration grade at different percentages. Scanning electron microscope (SEM) images show that 6% PET is the optimum mix proportion, and then ternary blends were done by mixing the prepared AP/PET with nano silica (nS) at different ratios (0.5, 1, 1.5, 2, and 2.5) wt./wt. The prepared coatings were evaluated by determining drying time, dry film thickness (DFT), adhesion strength, impact resistance, and flexibility. The formulated coatings were applied to concrete substrates, and the performance of coated concrete cubes was examined by determining water absorption, contact angle, and chloride diffusion. The durability of coated concrete was evaluated by measuring the changes in compressive strength after immersion in both sulfuric acid and sodium chloride solutions separately. The study proved the eco-efficient use of PET waste bottles in protective coating preparation, and the experimental results detected that nS has a significant mechanism for improving coating performance as follows; drying time of AP/PET-2 reduced with 61% as compared to AP/PET, the increment of DFT of AP/PET-2 was 25%, and adhesion strength was improved by 90%. On the same time, silica nano particles are mainly contributes for enhancing coated concretes. Where water absorption reduced with 75%, contact angle increased by 55%, and chloride permeability resistance enhanced to 40%. Finally, improvement durability of coated concrete was 25% and 20% after immersion for 28 d in both sulfuric (3%) acid and sodium chloride (5%) solutions, respectively.