Potential of Marine Clay for Cement Replacement and Pozzolanic Additive in Concrete

Marine clay is a low-grade kaolinsite clay commonly occurring in the coastal areas globally. Produced during excavation works, they are characterized by high silt and low kaolinite content, and hence, have little value for industrial applications. Since, the legislation in Singapore does not allow for disposal of these waste clays in the landfill, coupled with the acute shortage of space, marine clay poses a nuisance for handling and environmental issues. This project investigates the valorization of marine clay as a cement replacing agent and studies its pozzolanic potential. The clay after calcination at 600, 700 and 800 ℃ was used to replace ordinary Portland cement. Thermo-gravimetric analyses and isothermal calorimetry results indicate the potential of pozzolanic reactions with the consumption of calcium hydroxide and release of additional heat, respectively. Comparable strength was obtained at 28 days even at 30% by wt cement replacement. Furthermore, the 28-days compressive strength was not substantially affected with the calcination temperatures.