Open YPEC 2022

ON03 – Concrete without Cement: Waste-based and Eco-friendly Alkali-activated Slag (AAS) Concrete

The construction industry has long been considered a high carbon footprint industry owing to its extensive use of concrete. While cement, the essential ingredient of concrete, accounts for around 8% of the carbon emission globally. In view of the various carbon neutrality policies and schemes being promulgated, it is definitely the moment that great changes should be made. There is an immediate need for lowering the carbon emission and one of the best ways is to transform waste into something useful. One of the potential candidates is slag, a by-product of the iron manufacturing process. By mixing strong alkaline solutions with Ground Granulated Blast Furnace Slag (GGBS), Alkali-activated Slag (AAS) can be achieved whereupon having the potential to serve as a promising sustainable alternative to Ordinary Portland Cement (OPC). Apart from its substantially lower carbon footprint, it also exhibits better performance compared to OPC. From experiments, AAS demonstrates better chloride resistance and finer pores which is directly related to the durability of the material. Furthermore, AAS can be applied to other cement-intensive purposes such as ground treatment techniques e.g. Deep Cement Mixing which could be particularly applicable to places like Hong Kong having the need for reclamation.