Abstract
This research aimed to create value of construction and demolition waste to be able used as a recycled coarse aggregate (RCA) in durable concrete, based on 7-year field investigation in marine site. Fly ash was used to substitute Portland cement type I in RCA concrete varied from 0 to 50% by weight of binder with three W/B ratios and comparing to natural aggregate (NA) concrete. Cubical concrete specimens were cast having round steel bars embedded with various concrete coverings to evaluate the durability performances. After 28-day curing, the specimens were placed at a tidal zone in the gulf of Thailand and investigated both mechanical and durability performances at 7-year exposed period. Based on site monitoring, 15–25% fly ash RCA concrete with W/B ratio of 0.40 would be advantaged to resist destruction due to the marine attack when compared with NA concrete with the same water-to-binder ratio.
Highlights
Recycled coarse aggregates were derived from demolished concrete structures and were crushed into smaller particles to obtain specified sizes
It was found that use of fly ash to replace natural aggregate concrete ranging from 30 to 40% by weight of binder with Water to binder ratios (W/B) ratio as low as 0.40 would have less concrete destruction and prolong reinforced concrete structure subjected to marine environment
The use of fly ash in suitable amount could increase the compressive strength of recycled coarse aggregate (RCA) concrete to be as high as that of natural aggregate (NA) concrete
Summary
Recycled coarse aggregates were derived from demolished concrete structures and were crushed into smaller particles to obtain specified sizes. Recycled aggregates were usually used in a concrete mixture to conserve natural aggregates as well as to reduce waste of concrete debris in landfills The properties such as compressive strength, modulus of elasticity, water impermeability, abrasive resistance, durability, and etc. This research, studied the effects of fly ash content and water to binder ratio on compressive strength, chloride penetration, chloride diffusion coefficient, and steel corrosion of recycled coarse aggregate concretes subjected to marine environment up to 7 years. The findings would provide a long-term database and benefit to improve the durability of recycled aggregate concretes to be as efficient as those of natural aggregate concretes which are exposed in a severe condition especially in marine environment
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