why cracks deveop on the surface of a newly constructed jetty before application of live load?

Question

we have construted a jetty in our port.It is a purpose bult jetty for ccntiainer handling with heavy gantry crane to deal international trade.

Answer 1

You give very little to work on but lets try.
Assumptions made = Concrete jetty - cracks accross jetty and not in length of jetty.

1. Worst case - big cracks already showing =

The only reason this will happen is that the foundation was not designed correctly or was not built correctly or the foundation material is not stable enough to handle the weight of the jetty. It is now sagging at the far end and the cracks is an indication of this movement of the foundation/foundation materials. If there was not concrete piles used for the foundation or these were not put down to the correct depth, it is the problem. If big cracks show along the length - the same apply but only to one side of the foundation.

The minute you are going to allow live load to put further stress on the jetty, the cracks will open even wider and there is a possibility of total collapse.

2. Best case - only hairline cracks showing

No expandable joints were allowed/built and the concrete must move with the heat/cold. Hairline cracks will show but it will not widen with time.

3. You decide where in between this you are. If there is big cracks showing - get specialist engineers in to do a report before you allow any live load on the jetty - equipment may be lost and human lives as well.

Answer 2

I really do not know, but I do not want to be sitting in the crane should the jetty let go. Most of the time the problem is in the material and the mixture ,but if it has cracked in one place it will happen again when a stress load is placed on it.

Answer 3

I assume you are talking about cracks in the concrete. You get some cracks because concrete shrinks as it dries. You can lessen the occurance of cracking by the application of proper curing techniques and with proper setting of control and expansion joints. Some cracks appear because of stresses to the concrete, even before they receive any external loading. These should be examined before you put the structure into service. Small surface shrinkage cracks will probably not cause you any problems, but should be sealed to prevent water and other materials from getting into the cracks and making them worse.

Answer 4

Sounds like it dried out too quickly. Soap solutions added to the wet mix of concretes allow a slower setting time, with less likely hood of surface cracking.

Answer 5

These are most likely shrinkage cracks. These may be the result of too much water in the mix or they may be the reulst of overworking the finish.

Answer 6

good question