If the paste is ample in amount, but is too thin and watery to float the aggregate particles, what is the result?

Q. If the paste is ample in amount, but is too thin and watery to float the aggregate particles, what is the result?

A. The mixture will segregate in handling and placing. The thin paste and some of the fines in the fine aggregate will separate from the coarse particles to form laitance layers at the top of the mass, under larger aggregate particles, and will leave an inhomogeneous concrete below the weak top layer.

References: SP-1(02); ACI 304R-00

Topics in Concrete: Concrete Fundamentals; Placing