A study of the durability of recycled green building materials in lightweight aggregate concrete

• Recycled lightweight green concrete can be used effectively in recycling of waste resources.
• The slump increased or decreased with the addition of different types of recycled materials.
• The compressive strength was up to 56.1 MPa and it had better sulfate resistance.
• Add recycled materials may improve the durability of lightweight aggregate concrete.

In this study, waste tire powder and waste liquid crystal display (LCD) glass sand are used as recycled materials. With a fixed water to binder ratio (W/B = 0.4), the use of fly ash and slag as cement-replacement materials. waste tire powder and waste LCD glass sand, which passed the sieve screen size # 30(0.595 mm), were used to replace fine aggregates at 0%, 5% and 10% in producing lightweight aggregate concrete. The fresh property test was processed in accordance with ACI concrete mix proportion design. Harden and durability tests were performed at 7, 28, 56 and 91 days. The results showed that the slump increased or decreased with the addition of different types of recycled materials, but still met the design slump of 150–180 mm. Concrete workability and the unit weight decreased after adding rubber powder to concrete. As the replacement rates of waste glass sand and waste rubber powder increase, the compressive strength tends to decrease. At 56 days, the ultrasonic wave velocity of normal concrete was higher than lightweight aggregate concrete; the lightweight aggregate concrete with 10% glass sand provided the highest ultrasonic wave velocity of the lightweight aggregate concretes. Sulfate resistance tests showed that the normal weight aggregate concrete was better than the lightweight aggregate. Mixing two kinds of recycled materials also resulted in better resistance. Studies showed that adding an appropriate amount of recycled materials might improve the durability of lightweight aggregate concrete.