Development of admixtures and mixing design to reduce cement mixing ratio for retaining wall blocks

The admixture was developed to improve short and long age strength of concrete by replacing ferronickel slag, solid waste produced in the industrial ferronickel alloys smelting process, with fine aggregate. It was mixed into concrete and the estimated strength was evaluated through compressive strength and rebound hardness tests of retaining wall blocks. The fine aggregate replacement rate of ferronickel slag was fixed at 52%, and tests were conducted on concrete with 5 ~ 15% reduction in cement compared to fine aggregate depending on the amount of admixture mixed. In concrete using the developed admixture, the amount of cement mixed was reduced, but the compressive strength at 7 days actually increased. Therefore, it was evaluated as suitable for developing early strength. The developed retaining wall block was designed with a mix design that reduced cement by 10% by fixing the fine aggregate replacement rate of ferronickel slag at 52% and mixing the developed admixture. The compressive strength of the retaining wall block through the dry process was evaluated through the rebound hardness test method, and it was confirmed that the compressive strength performance of the product could be maintained even if the amount of cement was reduced.