Concrete Made by Recycling Industrial Byproducts
Lotte Engineering & Construction (Lotte E&C) announced on March 17 that it has successfully placed 46,000 cubic meters of eco-friendly concrete for the foundation work of Lotte Mall Hanoi, which is under construction in Hanoi, Vietnam.
The eco-friendly concrete can reduce CO2 emissions and boost a building’s durability. Lotte E&C produced the concrete by slashing the amount of cement to 50 percent and increasing the shares of fly ash and blast-furnace slag powder to 20 and 30 percent, respectively.
Fly ash is a fine powder that is a byproduct of burning pulverized coal in electric generation power plants. Blast-furnace slag powder is a powder made of blast-furnace slag from steel mills. The use of the two industrial byproducts for concrete production reduces carbon dioxide and energy consumption compared to regular concrete.
In Hanoi, construction companies had used concrete that only contained fly ash. But blast-furnace slag became available after a steel mill opened in Hanoi in 2019. In response, Lotte E&C conducted a joint study with the Vietnam Institute for Building Science and Technology (IBST), a construction technology research institute affiliated with the Vietnamese Ministry of Construction, to develop a concrete mix using blast-furnace slag powder.
As a result, the builder developed concrete that lowered hydration heat generated during the concrete's hardening by 10 degrees Celsius compared to other concrete mixes, improved the long-age strength of concrete after 90 days by 20 percent and improved water density by two notches (33 percent).
In addition, this technology contributes to the protection of the environment by reducing the use of cement that emits a large amount of CO2, a greenhouse gas, during the manufacturing process, and using blast furnace slag powder and fly ash which emit about 3 percent carbon dioxide compared to cement as a substitute. In fact, the technology was applied to the construction of Lotte Mall Hanoi, pruning CO2 emission by 4,920 tons.