Common problems of fresh concrete will be discussed under 4 modes which are: inadequate workability, segregation, bleeding and harshness.
Workability is the ease at which concrete can be placed and compacted. When inadequate, it leads to segregation and bleeding. Workability depends on quantity of water, shape of aggregates and their percentage in concrete.
This is the separation of coarse particles in green (fresh) concrete. It happens due to insufficient finer particles. Segregation can also be caused by throwing concrete from great heights at time of placing. Segregation causes loss of cohesiveness in concrete which results in honey combing and loss of strength.
The appearance of water with cement particles on surface of freshly laid concrete. Caused by excessive quantity of water in the mix or too much compaction. Bleeding causes pores to form on concrete and renders it weak.
Fresh concrete is said to be harsh when it becomes difficult to obtain a smooth surface finish. It is caused by insufficient quantity of fine aggregates or insufficient quantity of water.