Question

Q1. Briefly describe two contaminants that are routinely found in marine dredged aggregates which would have to be reduced or removed if the aggregates were destined to be used in reinforced concrete. For each of these contaminants explain briefly what problems or issues might occur if high levels of the contaminant were to remain in the aggregate.

Answer 1

Problems with marine aggregates in concrete :

1. Chloride and silica content in aggregates :

If more chloride and silica is present in aggregates it may lead to the corrosion of reinforcement. A concern to specifiers is the need to avoid corrosion in concretes containing steel reinforcement.so if large amount of chloride and silica content aggregates are present we need to separate that aggregates to avoid corrosion.

2. Fineness and surface of aggregate :

Since Marine aggregates are very fine in nature and round surface. Round surface aggregates gives more workability. So as in the point of workability it gives more value,but at the final the compressive strength of concrete is decreases. So we need to separate that fine and rounded aggregates.

Thank you. Hope you understand. If you have any doubts comment me.