By Candice Lim
In Singapore, where natural resources are scarce, technology is used to create usable materials or improve on processes in industries where immense quantities of resources are required, such as in construction. The treatment of incineration bottom ash (IBA) or slag created via gasification has also opened doors to using it as an alternative material in construction, potentially replacing the need for sand. Rising temperatures and more erratic weather patterns from climate change will worsen resource constraints and supply shocks.
Singapore has created Newsand from repurposed municipal solid waste, and it may be used in construction in the country. It is hoped that this material will help to close the waste loop and extend the lifespan of Singapore’s landfill on Semakau Island. Newsand can currently be made from IBA. Trials and tests will be conducted, with small-scale constructions being put in place to experiment with this material. The National Environment Agency said 3,000 tonnes of IBA generated from the waste-to-energy plants in Singapore will be collected and treated for use as a road base or sub-base material in road construction projects. These efforts are a culmination of efforts over the years to turn trash into resources and close the nation’s waste loop.
Singapore has had some success, recycling 60 per cent of its waste since 2012 by focusing on individual waste streams. This has led to a nearly 100 per cent recycling rate for Construction and Demolition (C&D) waste, as well as ferrous and non-ferrous metals.
HOW C&D WASTE IS PUT BACK INTO BUILDINGS
The Demolition Protocol was implemented by the Building and Construction Authority (BCA) to help demolition contractors plan their procedures to maximise C&D waste recycling. Under this protocol, reusable and non-reusable parts of a building have to be identified before separately dismantled and removed. Reusable parts (including piping and wiring) are separately binned and sent to a recycling facility. Non-reusable parts (such as ceiling boards and tiles that contaminate the concrete debris) are discarded. Demolition starts only when the building has been stripped to its bare frame. This protocol has led to the development of several new materials, such as recycled concrete aggregate (RCA), which is made up of 70 per cent demolition waste that is reclaimed from waste concrete made with natural aggregates. The C&D waste undergoes a preliminary process where ferrous metal are crushed and removed, followed by removal of foreign materials such as bricks, plastics and asphalt. Thereafter, RCA will be further crushed and screened into various sizes, eventually resulting in a stockpile of RCA for various usage. For instance, Samwoh Corporation’s Eco-Green Building was constructed using concrete with up to 100 per cent recycled construction aggregates.
Zero Waste Master Plan by the Ministry of the Environment and Water Resources