Recycling and Valorising Ground Granulated Blast Furnace Slag (GGBS) and Waste Plastic in Printable and Sustainable Concrete

Problem Statement

• Concrete material results in high CO2 emission
  Cement is one of the major sources of greenhouse gases and it is estimated that each tonne of Portland cement releases 1 tonne of CO2.
• Increasing plastic waste in Singapore
  According to the statistics generated by National Environment agency (NEA), in 2017, 815,200 tonnes of plastic was generated and only 6% (49, 000 tonnes) of it was recycled

Objective

The key aim of this project is to develop and commercialise a printable mortar mix that can be printed into sustainable concrete building components.
The main objectives are:

• To produce and study the workability/ flowability, extrudability, buildability, compressive strength, and speed of setting of concrete mix that contains Ground Granulated Blast Furnace Slag (GGBS)GGBS and/or waste plastic (namely, Polyethylene Terephthalate (PET))
• To produce, study and optimise the properties of a 3D printed concrete building component.

Key Benefits/Outcomes

Various formulations of GGBS + PET combos were evaluated.

• GGBS can be used as cementitious mix, which is comparable to conventional cementitious mix that has high compression strength.
• Adding PET to GGBS is not better than GGBS mix. Nonetheless, GGBS + PET mix can be used for different applications e.g. archaeology artifact printing, parts that require less mechanical strength.
• Addition of PET also causes the concrete mix to behave like semi-solid which helps in accelerating the curing for printing.