A REVIEW ON OPTIMIZATION OF CONCRETE USING PACKING DENSITY THEORY

Abstract

A number of theories have been developed to optimize concrete. Amongst them the optimization
of aggregates is advantageous for economical and technical reasons. Packing of an aggregate blend is a
measure reflecting how solid part and air voids would share the volume occupied by the blend. It is usually
measured in terms of ‘‘packing density”. Given a unit volume filled with particles, packing density or
packing degree is the volume of solids in this unit volume and is equal to one minus the voids. Lesser the
voids lesser will be the requirement for cement paste and thus the defects arising in concrete attributed to
cement paste can be mitigated to a certain extent. Packing density is a function of gradation, shape of the
particles, texture of aggregate surface, type and amount of compaction effort, aggregate strength, layer
thickness. Some general guidelines such as ACI 211 – ASTM C 33, Compressible Packing Model, Shilstone,
18-8 specification, based on field experience, have been developed. One is intended for users of the ACI
211 – ASTM C 33 method who want to optimize aggregate proportions. The other is intended for eventual
users of the Compressible Packing Model. CPM is more complex and requires more testing than ACI 211 –
ASTM C 33. As a result, it might not be the preferred procedure for some users. ACI 211 - ASTM C 33 is
focused on the proportioning and optimization of aggregates. A detailed comparison can be done using
different proportioning guidelines for optimization of concrete.