A 623-foot-long bulk carrier arrived at Chittagong, Bangladesh coming from Biringkassi, Indonesia, to discharge her cargo consisting in 55.004,496 MT of Ordinary Portland Cement Clinker. Discharging operations were performed, but were stopped several times due to raining and bad weather. Master reported that cement residues were hard stuck on holds’ steel plate and frames and cannot be removed with normal crew cleaning using vessels means including chemicals. The same occurred on deck. High pressure washing, sand blasting, painting, etc. in shipyard were required to remove the cement raising the claim to about 500,000 USD.
Following our depth investigation, we concluded that, considering the area, i.e. Indonesia and Bangladesh, and, therefore, the weather condition during loading / voyage / discharging (high temperature and humidity), the cement was subject to an extremely high level of temperature and humidity. The strength and microstructure of concrete are known to be affected by humidity and subsequent drying shrinkage.
Thus, concrete resistivity is directly related to relative humidity and is also affected by temperature. Actually, the humidity and subsequent drying shrinkage influence the microstructure in many levels and affect the mechanical properties. In one respect, which allegedly happened in this case, the humidity and subsequent drying shrinkage tend to increase strength by increasing surface energy and increasing bonding between particles of calcium silicate hydrate (C-S-H).
All above resulted in wet cement which, becoming dry, needed to be immediately removed in order to avoid cement residues stuck to vessel plating and stiffeners. Therefore, cement cargoes, can prove to be extremely problematic when carried in conventional bulk carries. If not dealt
with in appropriate manner, cement carriage can result in cleaning problem, as in this case. it follows that the timing of starting to blowing out/sweeping the cement powder from deck and cargo holds is the most important detail to be follow after cement discharge. In this respect,
the cleaning procedures started 12 hours after completion of discharging, resulting, probably, in cement sticking.
