Methods for Pre-packed Concrete:

The pre-packed aggregates can be grouted by the following methods:

(a) The mould could be filled with grout and the coarse aggregate can be deposited in the grout.

(b) The grout could be poured on the top surface of aggregate and allowed to penetrate to the bottom. The method is particularly useful for grouting thin sections.

(c) Pumping the grout into aggregate mass from bottom at carefully designed positions through a network of pipes. The formwork should be constructed at the top of the coarse aggregate in this method.

The grout pressure will be about 0.2 to 0.3 MPa. The quantity of grout should be estimated from the void contents of the coarse aggregates. The pre-packed concrete has lower drying shrinkage and higher durability, especially freezing and thawing resistance compared to ordinary concrete for the same proportions. The rate of development of strength is comparatively slow for the first two months and the eventual strengths are about the same as for normal concrete. This method is very much useful for underwater construction and repair work of mass concrete structures, such as dams, spillways, etc.